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February 8

Where can I find information about NLP?

Especially about using NLP to make me invisible! I heard there's a British guy who perfected this.TinyTonyyy (talk) 01:35, 8 February 2009 (UTC)

Which NLP are you talking about? I don't think any of them offer a useful method of invisibility. Algebraist 01:57, 8 February 2009 (UTC)

I believe TinyTonyyy is referring to neuro-linguistic programming, which British magician Derren Brown claims (or, apparently, is generally thought to claim) can make someone think Brown is invisible. But Brown is a magician and showman by trade, and if you believe that you can do this kind of stuff in real life, you're probably really missing the point of performing magic on stage: it's all skilled about misdirection, illusions and entertainment, not a display of actual supernatural powers. -- Captain Disdain (talk) 03:46, 8 February 2009 (UTC)

TinyTonyyy, (and that could be your problem right there...) if you think you can stroll unobserved around the girls' dressing sheds at the beach, forget it. The ambient steam around your body gives your presence away. I know. Myles325a (talk) 01:19, 16 February 2009 (UTC)

effect of pulse polio programme on scheduled vaccinations!

hey. can anyone help me out with this one?

recently according to some research in india it has come to light that because of pulse polio pragramme people from villages are not taking their kids for getting the scheduled vaccines! i wanted to do a project on this topic. can anyone give me any information about this topic? i would be really grateful to anyone who helps! thanks. —Preceding unsigned comment added by 59.92.242.169 (talk) 16:05, 8 February 2009 (UTC)

I'm not sure what you mean. You seem to be saying that the Pulse Polio program is causing people to not be vaccinated, which seems unlikely, seeing that the whole purpose of the program is to do just that. --Milkbreath (talk) 16:53, 8 February 2009 (UTC)

Just a guess, but maybe the OP is saying that some people are skipping standardized ("scheduled") polio vaccinations, perhaps at their own cost, because they expect to get vaccination through the pulse programs. It stands to reason that the scheduled vaccine would be optimized to the child's age, whereas the pulse program would not be individualized. The population effect of the pulse program would be beneficial (catching many who would not otherwise get vaccine) but might have the unintended effect of delaying vaccination of those who would have gotten it anyway. Seems like a good thing to study, and I have a sense other vaccination programs have seen the same thing. --Scray (talk) 17:08, 8 February 2009 (UTC)

Possible. What I first thought was that a determined program to vaccinate against one disease might have the paradoxical effect of reducing overall childhood immunization compliance in uneducated mothers who would suppose that a little bit of vaccination is good enough, not differentiating between the different vaccines and forming wrong ideas around the existence of multiple vaccines like MMR. Word of mouth is a poor disseminator of scientific ideas, I'll bet. But I'd like 59.92 to give us a little more to go on, like what study he's referring to. --Milkbreath (talk) 17:25, 8 February 2009 (UTC)

Colour of the Sun

Having done an Astronomy qualification, one thing still puzzles me - why the Sun appears yellow. It seems several sources diagree slightly on this: whether it is because the scattering of blue light in Earth's atmosphere leaves yellow (i.e. white minus blue = yellow) or whether it was because the atmosphere of the Sun - white light came directly from the Sun, but yellow could also be emitted in other directions, absorbed by Hydrogen (or Helium) and re-emitted in the direction of Earth. Are they both factors, and, if so, which is more important? - Jarry1250 ^{(t, c)} 16:08, 8 February 2009 (UTC)

As far as I know, it's just scattering in our atmosphere. The light coming from the sun is thermal radiation from the photosphere. It is effectively a black body at 5800K, which corresponds to "white hot". --Tango (talk) 16:17, 8 February 2009 (UTC)

this is responding to an answer the poster had already deleted, not to Tango. Sorry, I was not paying attention. SpinningSpark

Sorry to be contrary, but the peak wavelength is actually well in to the green band, very nearly cyan, and nowhere near yellow. File:Solar Spectrum.png. Some astronomy books quite perversely insist on calling G2 stars "green stars". The particular mixture of colours we get from the sun is white by definition (a piece of paper reflecting all wavelengths appears white in sunlight). The yellow appearance is indeed due to Rayleigh diffraction scattering but is amplified in the brain through a visual processing of "integrate to white". That is the brain's visual processing is attempting to remove any colour bias of the light source from the scene. The blue sky requires yellow somewhere in order to integrate the whole scene to white. Rooms lit by tungsten fil. lighting look distinctly yellow, but should look a lot more yellow if it where not for this process. There is also the matter of refraction as the sun gets low in the sky causing the loss of blue. The sun low in the sky is easier to look at than at midday and at these times it really is orange or even red. SpinningSpark 16:58, 8 February 2009 (UTC)

Hello spinningspark. Yeah that was me. I remembered reading in an astronomy textbook that "our sun is a yellow star", but I did some look up immidiately and found that was not exactly true. Thanks for your explanationn, cheers! -- ReluctantPhilosopher (talk) 18:51, 9 February 2009 (UTC)

Spinningpsark alluded to this, but it bears saying by itself: We perceive the Sun as yellow because, when we can look at it, it's low in the sky and the higher frequencies are scattered away. When the Sun is directly overhead, it's white. In fact that's probably pretty much the definition of white. --Trovatore (talk) 21:47, 9 February 2009 (UTC)

Call me an idiot if you will, but when the Sun's overhead, the sky is still blue; therefore some blue light must be scattered. Does this mean the Sun is still yellow? And is my factor about difraction in the outer layers of the Sun wrong (which is fine) or does it not have a noticable effect? - Jarry1250 ^{(t, c)} 22:05, 9 February 2009 (UTC)

Yes, the sun will still be slightly yellow, just not as much. I didn't really understand what you were saying about the outer layers of the sun... the light we see comes from the photosphere (one of the outer layers) and is emitted because it is hot (the core is hotter, but the light from that is absorbed by the outer layers, which are pretty opaque). --Tango (talk) 22:17, 9 February 2009 (UTC)

Our eyes and brains have evolved to treat sunlight as "white" - regardless of what energies are emitted at what frequencies - the totality of sunlight MUST be "white" because it is the very definition of the word. Since the sky is blue - we know that some of the blue that comes directly from the sun must be being scattered across the sky - ergo the direct path of light from the sun must be white minus blue - which is yellow. SteveBaker (talk) 03:10, 10 February 2009 (UTC)

The sun looks white when it falls on a surface on a clear day. But when you look (briefly!) at it it is surrounded by a blue sky, and color contrast may make it look yellow. Edison (talk) 21:03, 10 February 2009 (UTC)

Sleep

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis, prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the Reference Desk's talk page.

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis or prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the Reference Desk's talk page. --~~~~

--Scray (talk) 17:00, 8 February 2009 (UTC)

Whether this is or isn't a request for medical advice is being discussed here: [1]. StuRat (talk) 22:28, 9 February 2009 (UTC)

I won't answer any questions about whether you personally will suffer from having your sleep schedule split in two, but will make some general observations on sleep patterns:

1) The most important thing is to get enough total sleep.

2) The amount of sleep each adult requires varies quite a bit, but the 7-8 hour range is typical.

3) There is a certain minimum amount of time required for each sleep session to get to the deepest stages of sleep. Our sleep article seems to mention 90-110 minutes for each stage, and 5 stages of sleep (some repeated), which would give me 450-550 contiguous minutes of sleep needed to get all the stages. That's 7.5-9 hours. So, if those calcs can be trusted, split sleep cycles wouldn't work. However, there are cases of people with odd sleep patters, such as Thomas Edison, who would take many short naps in his office instead of going home for a full night's sleep, without any apparent ill effects. This suggests that the early sleep stages can be shortened, as needed, by some people, to make up for a deficit in the later stages. So, I'd say whether an individual can cope with a split sleep schedule depends on their own biology.

4) There are some cultures where a split sleep schedule was traditional. A siesta, for example, was often taken at the hottest part of the day in tropical climates, as anything more ambitious would be likely to result in overheating. Presumably, these people needed less sleep at night, so can take advantage of cool mornings and evenings to get work done. This pattern of sleep may be less common now that air conditioning is common. StuRat (talk) 18:31, 8 February 2009 (UTC)

Splitting one's sleep schedule deliberately can be known as polyphasia, and is the subject of self-research. BrainyBabe (talk) 21:32, 8 February 2009 (UTC)

A Spaniard I knew in the UK said that in Spain people typically went to bed much later than in the UK and got up early; so they got less sleep at night. However, she also said that she found she felt extremely refreshed after being in the UK a few weeks and shifting to getting more sleep at night, and found it shattering to go home and function on the little sleep typical there. One person's experience in one area... 79.66.57.25 (talk) 23:34, 8 February 2009 (UTC)

The British navy managed somehow to win the Napoleanic wars using crews (officers and men) who stood four-hour watches (four hours on, four hours off) for years at a time. I thihk the practice continues to the present day in most navies. See Watch system. -Arch dude (talk) 21:35, 8 February 2009 (UTC)

There used to be an old saying: Nature requires five hours, convention says eight; sloth takes eleven and wickedness fourteen. People who claim to survive on less than five hours' sleep tend to take mini-naps during their day, and people who stay in bed more than eight hours tend to be awake for some of that time. I agree with StuRat that the amount of sleep required does seem to vary between individuals, with some apparently needing less, but it is also a matter of habit. Lack of total sleep is normally easy to detect because eyes will close involuntarily whenever adrenalin levels drop. The body also seems to need more sleep when it is engaged in repair work, after infection or injury. Dbfirs 21:43, 8 February 2009 (UTC)

The way I read it (not sure where) was:

Nature takes five

Custom grants seven

Laziness takes nine

And Michaelmas eleven

No one I know actually observes Michaelmas (I couldn't even tell you what time of year it is without looking it up) so this is perhaps not as meaningful as it could be to me. --Trovatore (talk) 00:11, 10 February 2009 (UTC)

what is a time that is CERTAINLY too short for a person to displacce their hand by 1 meter ?

so, to give you an idea of why I'm asking, I'm thinking about what notes are a physical impossibility to play in immediate succession on the piano (where "immediate sucession" would be a 64th note, or 128th or 256th, 512th, 1024th or whatever), even for someone who was playing the piano since birth + was the world's record fastest piano player + did this particular test on performance enhancing drugs... so I'm really asking about physics possibility!

what might be a good way to come up with a time in which it is CERTAIN no one can move their hand by, say, 1 meter, even once. I have some ideas for upper bounds: you can figure out the "jerk" that would be required (change in accelleration) and figure out what the time interval would be for which such a jerk would be sufficient to sever a hand. I mean, if you think about it, there MUST be a certain jerk that would sever a person's hand completely! But this is a way way way way way too high upper bounds! I'm looking for a more reasonable one... Any ideas?

One approach could be like, taking the power required for the displacement in the given amount of time, and making it larger than the maximum power human muscles can produce for any lenght of time. But it's hard because there are SO many muscles, the maximum instantaneous power oculd be huge -- I don't see why it coulnd't a gigawatt, if we're only talking about a SINGLE microsecond.

So any way to estimate physical impossibility?

p.s. I have another upper bounds: the time it takes to move 1 meter at the speed of light. but 1 m / c is 3.33 nanoseconds.

A boxer is certainly snapping a jab as fast as he can. The British Journal of Sports Medicine has an article on the biomechanics of punches that gives a speed figure of about 9 m/s, which would be 111 ms for one meter, a little more than a tenth of a second. If you halve that to account for mutants like Roy Jones I think you have a reasonable limit. --Milkbreath (talk) 18:47, 8 February 2009 (UTC)

9 m/s sounds low. That's only about 20 mph! A major-league pitcher can deliver a baseball at up to 100 mph, occasionally higher. Granted he wouldn't be able to do that if he threw it by extending his arm straight from his shoulder, but still, five to one? Really? --Trovatore (talk) 09:19, 10 February 2009 (UTC)

Is that with or without roller skates on their elbows? It was Robert Rankin's idea, not mine. ៛ BL ៛ (talk) 19:03, 8 February 2009 (UTC)

I thinks it's a silly question, but let's play anyway. For a single pair of notes, the player does not need to stop his hand over the first or last note. His hand can already be moving in the correct direction. -Arch dude (talk) 21:30, 8 February 2009 (UTC)

The question doesn't say whether the player is bouncing one finger on one key, or can use multiple fingers and/or hit different keys. I initially read the question as one&one (since asked about short individual notes, not speed to accomplish a range or maximum range in a time)--Arch dude's "running start and over-run the base" don't help:( However, then it continues with ideas about moving one's whole hand and motions on the order of a meter, so now I'm not sure we're just on one key. Interesting question about maximum acceleration before joint dislocation though! DMacks (talk) 07:24, 9 February 2009 (UTC)

I don't understand the need to move your hand by a meter - that's an awful long way on a keyboard instrument! Surely the shortest note is the time between depressing the key far enough to launch the piano's hammer toward the string to releasing it far enough to actuate the damper. I play keyboard instruments - but I'm used to electronic keyboards. On occasions I've played a real piano, the force you have to apply to the key and the relative lack of control you have over the note duration seems like a much bigger limitation than how fast my fingers can move. So I think we should be considering:

• The shortest duration of a single note on an electronic instrument (from "Note-On" to "Note-Off" in MIDI terms).
• The shortest time to move finger/hand from one key to another over a 'reasonable' span.

We do have numbers for typists...that's gotta be comparable. A good typist can reach 120 words per minute - and (I believe) the metric assumes an average of four characters per word plus a space - so that's 600 keystrokes per minute - ten per second. Stenographers can manage 250 words per minute - but they never have to move their fingers from one key to another - and most words are a single "chord"...so again, we're probably around 10 keystrokes per second. The world record for a stenography machine is 375 words per minute - so the best that people can do is only maybe 50% better than a normal but experienced person.

So on that basis - I'd guess that the answer is something like 15 notes per second per finger. But not on a piano - and not if hands have to move large distances between notes.

SteveBaker (talk) 16:39, 9 February 2009 (UTC)

tips to enthuse proto-computer scientists

I have to encourage a group of moderately disaffected youngsters to take seriously the need to express themselves clearly in written English. If all goes well, they will be accepted into Year One of university computer science programs. Their maths and CS abilities are in need of a little attention, hence this Year Zero program. Their English is in need of a lot of attention, hence this remedial class. As a generalisation, the group as a whole was "never good at English" at school, which is why they have opted for CS degrees. Some of them see little point in attempting to improve their written English, as they do not expect to have to use it in the careers they hope for.

My question to you: many of you, I take it, have or have had jobs to do with computers. Many of you enjoy the art of written expression (attested to by your voluntary participation here). How would you suggest I awaken the interest of these students? Or, if that is too blatantly an opinion question, what sources can you point me towards that demonstrate the value of clear written expression in the obtaining of desirable CS jobs? How does good English help in a good career? Many thanks! BusinessAsUnusual (talk) 21:56, 8 February 2009 (UTC)

You can always divide them into groups of three or four and make a competition which group writes a better l33t <=> English interpreter code :) --Dr Dima (talk) 22:34, 8 February 2009 (UTC)

If their English, Maths and CS skills all need extra help, are they really cut out for a Uni CompSci course? Or university at all? There are plenty of jobs out there that don't require degrees, perhaps you should be concentrating on giving them the skills they need for them... </rant!> Anyway, if you insist, you could show them some computer manuals - technical writing is a very important skill, you can't be a good programmer (I'm assuming if they aren't good at maths that they equate computer science with programming) if you can't write decent documentation. The Computer reference desk may have better answers. --Tango (talk) 23:41, 8 February 2009 (UTC)

Documentation is a good point about the need for clear writing! How about having them write some simple program (whatever is at their level) and user-doc for it. Then put them and "some users" (could be you, could be some real-world people:) in two different rooms and let them field customer-support calls for users following the docs. DMacks (talk) 00:09, 9 February 2009 (UTC)

You can be bluntly honest with them. They are not special. Nobody cares about them. If they want a job, it is up to them to convince a group of people, likely much older than they are, that they are willing to conform to the university or work environment. If proper English is used, the chance of being accepted increases drastically. If, instead, they treat the situation like an instant chat and blow it off, they themselves will be blown off. This is seen here on the RD every week. People who ask questions with clear English tend to get good answers. People who use poor English do not receive good answers. -- kainaw™ 02:05, 9 February 2009 (UTC)

You could split that even further (based on two flavors of this type of student attitude). Type 1 is that they're (at least in their mind) really really good but just cooler, nonconformist, "not an uptight suit" and so they don't need no formal book-learnin' English. It's fine to be casual, but unless you can express yourself clearly and precisely and at least neaten up when the situation calls for it, nobody will recognize (i.e., "hire") how good you might be. Type 2 is the fact that the economy sucks and there's always competition and others who are at least as smart and experienced vying for the same job. Even if your CS skill can be recognized, someone who is technicalls skilled and also more polished and able to dress up and become clear and formal when the situation dictates will get the job every time. DMacks (talk) 07:09, 9 February 2009 (UTC)

A large portion of my time as a computer programmer was spent trying to get the customers to define the specs. This involved many e-mails which needed to ask very specific questions in order to get good enough answers. StuRat (talk) 07:56, 9 February 2009 (UTC)

Assuming they ever make it into the world of employment, they will also need some administrative skills, because it seems to be the policy of larger corporations to make people with no training in administration do their own administration. Admin skills don't just involve the ability to type fast! They will need to fill in forms - which involves reading them in the first place, deciphering what is required in each space of the form, composing entries for each space in the form which are legible and make sense - and also to speak to other people clearly and in a language the other person can understand, which doesn't involve grunts! Finally, their willingness to learn is crucial to making a success in IT based provision. They will always be asked to work in a language they've never used, with software and hardware they've never used, and systems they are not familiar with. How do they learn them? Well, these days, it's FOFO - so back to books usually! BTW I love the help desk scenario as given above - most geeks seem to think that end users are irrelevant, whereas without end users there's no point to any computer system. --TammyMoet (talk) 09:48, 9 February 2009 (UTC)

I've been a computer programmer for 35 years - and I'm very certain that I've written more English than C++ code (or any other kind of code) in the course of my job in all of those years. Documentation, comments inside code, messages to users from within your code...all of those things require good English skills. It's certainly a fact that you need good English skills. It's also a fact that many programmers are just like your kids and hate being made to write documentation and copious code comments...sadly. It's going to be hard to convince them that this is true though. I have a hard enough time making people write decent documentation who have the requisite skills. Math skills MAY be less important - it depends on what you're doing. You can write accountancy software knowing nothing but how to add and subtract...but if you want to write video games - your math skills had better be razor sharp or you won't even make it to interview. When the companies I have worked for are thinking of interviewing a job candidate, we first subject them to a half hour to an hour of 'phone interview' which probes math skills in great detail. Fail that and you'll never get as far as the front door. One of the things beginning programmers don't understand is that programming is a team activity. It's very rare indeed for someone to be able to write something by themselves. Yet schools and colleges (and people playing around with computers at home) pretty much treat it as a solo activity. When you have 10, 20, 50 people writing a piece of software containing several MILLION lines of software - the ability to communicate effectively is paramount. A lot of that is in email - Wiki's and (rarely) paper documentation...but it's English. If you think you can write emails in 'leet-speak'...you've got to be kidding! You'd be laughed off the team in the game programming teams I've worked on.

Sadly - I can't think of any way to enthuse them. I suppose you could get a real, live game programmer to come and talk to them (most companies are receptive to the idea of having their staff take a couple of hours out to go talk to local school/college kids once in a while). Unfortunately, your kids will cynically see this as another "Stay In School! Study Hard!" lecture and they'll likely just tune it out.

I applaud your efforts though. SteveBaker (talk) 16:20, 9 February 2009 (UTC)

I've known schools and universities do group programming assignments, but they rarely work very well. It usually ends up testing whether or not you can reach the end of the assignment without killing the rest of your group. The problem is that all the students are expected to work as equals, and that rarely works (unless you have significant maturity, experience and motivation, 3 things students are frequently lacking). In the real work there are hierarchies, they may be very loose most of the time, but they are there when they're needed, that is never replicated in the academic environment. Group assignments are also usually very badly graded - everyone gets pretty much the same grade regardless of how much they did (which harms the motivation element). --Tango (talk) 16:48, 9 February 2009 (UTC)

Yeah - I agree, this is hard to score and hard to motivate. But that's how the real world is. You WILL have poor team members - you WILL have the odd super-programmer who can write code (literally) a hundred times faster than the weakest member. This can get very difficult. Particularly with modern agile development methodologies (eg Scrum (development)) where it's impossible for the weaker members to hide their lack of ability. But team development is where it's at - and communication is everything once your team is more than three or four people. Documentation is vital - I even document my own solo projects because the "me" in the future is not the "me" now - he'll have different memories and a different perspective on the project - and a handy memory jogger as to why the "me" of today did what he did is often invaluable. SteveBaker (talk) 03:05, 10 February 2009 (UTC)

TV Noise

My girlfriend hears a high pitched noise when the tv set is on. She can tell when it's on even if she's not in the room.

what is she hearing?192.136.22.5 (talk) 23:51, 8 February 2009 (UTC)

Is it an old CRT TV? If so it will be the 15kHz line scan frequency. SpinningSpark 00:02, 9 February 2009 (UTC)

Specifically, from the flyback transformer or associated components. --Anonymous, 04:27 UTC, February 9, 2009.

... although obviously we can't be certain, and if your girlfriend has any concerns she should consult a professional and get her hearing tested. Gandalf61 (talk) 07:13, 9 February 2009 (UTC)

I have a suggestion. Since high frequency hearing decreases with age, give that TV to someone old enough not to be bothered and get a new one (or one in trade for this one) that won't drive your g/f crazy. After all, that's your job. StuRat (talk) 07:49, 9 February 2009 (UTC)

It's his job to get rid of the things that drive her crazy or is it his job to drive her crazy? Does being ambiguous drive your wife/girlfriend crazy, Stu?  :-) Dismas|^(talk) 08:45, 9 February 2009 (UTC)

It was intentionally ambiguous. It wouldn't have been funny if I'd said "it's your job to drive your g/f crazy" (although that still has an ambiguity to it) any more than if Bush'd said "it's our job to destroy this country". However, when he said "There are terrorists who want to destroy this country, but we won't let them, that's our job" (paraphrased), that was funny. StuRat (talk) 20:00, 9 February 2009 (UTC)

I hear high pitched noise from a great many common electronic devices like TVs (including a new flat screen one), ethernet hubs (wireless or not), palm pilot type devices, digital clocks, etc. Often the noise is very quiet. Certainly these sounds are generally overwhelmed by the relentless household noise of the furnace, refrigerator, misc computers, etc. Sometimes I try to turn it all off. Inevitably I end up still hearing some electronic noise after turning the obvious things off and search around until I discover that there is a little hiss coming from the egg timer, or something. But it is always very striking how quiet it is when all the electrical things are off, making me realize how a myriad of ordinary household noises add up to a constant din. I guess most people are just used to it, or don't hear it as well? Anyway, it makes me wonder what is it about electronics that makes so much noise--hisses and hums and such... usually fairly quiet for a given device. Sometimes I've noticed solid state devices, like musical synths, get noisers over the years. Could it have to do with power supplies? Do Operational amplifiers tend to produce a bit of noise? Curious. Pfly (talk) 08:50, 9 February 2009 (UTC)

So others do hear it! I grew up being able to know whether or not a household had their television on, even if the volume was turned all the way down, and I could determine this from the street in front of their house, with all of the house's doors and windows shut tight. That's how sensitive I was to that high pitched tone that others claimed they couldn't hear. As Pfly noted, it is much easier to hear those noises when other sound sources are at a minimum, but a television in the same room with me has an undeniable high pitched whine underlying every minute of usage. I used to hear a similar high pitched noise from computer monitors but either technology has rid monitors of that excess noise or maybe my hearing isn't what it used to be. 152.16.16.75 (talk) 11:26, 9 February 2009 (UTC)

Additional WP:OR and anecdotal evidence... Some friends of mine live off-grid. When house-sitting for them, I've noticed that their house is just quieter than any other house. When I lay in bed at night there, it's quieter than my own on-grid house at the same hour. We both live far away from any neighbors. Dismas|^(talk) 11:31, 9 February 2009 (UTC)

Yes, others certain can hear it. I can't, but I know at least 2 people that can tell if a room contains a TV on standby from outside the room (with the door shut). --Tango (talk) 11:36, 9 February 2009 (UTC)

I, too, hear TVs and such, provided that there are no other substantial noises. From what I learned in the past, I will probably lose this ability within a few years, since as humans age our ears lose sensitivity to sounds in the ultra-high frequency range. See Presbycusis and The Mosquito.-RunningOnBrains 18:45, 9 February 2009 (UTC)

Don't get your hopes up too soon. I've developed a gap in the higher reaches between inaudible to others and high pitched, but can still hear whether the bug chaser or the TV is on while it's muted. And the sound does stop when I unplug it so it's not tinnitus. 76.97.245.5 (talk) 21:56, 9 February 2009 (UTC)

Many people could hear the 15 khz TV noise when young.Audiograms taken over the decades may show that 15000 Hz is clearly audible in the young, but exposure to noise can cause severe hearing loss above 4000 Hz, Then when they are old, they may hear similar high pitched noise all the time, in the form of Tinnitus, although that is likely to be pulsating rather than steady. Exposure to loud noise like music, aircraft, traffic noise, shooting, mechanical or construction equipment, screaming babies over the years can eliminate the ability to hear high frequencies by causing Hearing impairment. This has led to Noise regulation laws. Edison (talk) 20:54, 10 February 2009 (UTC)

February 9

Decomposition of Styrofoam and Plastics

How many years does it take for styrofoams and plastic materials to decompose in the ground? Sonic99 (talk) 00:10, 9 February 2009 (UTC)

Styrofoam does not biodegrade at all. It will stay in the ground indefinitely, or be eroded mechanically into progressively smaller fragments. See biodegradation, styrofoam, and Polystyrene#Extruded_polystyrene_foam. The article on biodegradation has data on some other plastics, as well. All this being said, it is possible that microorganisms will be found that can digest or degrade polystyrene in some way. --Dr Dima (talk) 01:53, 9 February 2009 (UTC)

I did a quick google search just now, and I see papers on the potential use of Xanthomonas sp. and Sphingobacterium sp. for polystyrene decomposition. You can redo the search and follow the links if you want to do some research on the subject. --Dr Dima (talk) 02:01, 9 February 2009 (UTC)

I'm surprised how long the myth of "eternal" plastic is lasting. Long after the fact that it isn't has started staring us in the face. Maybe not enough people have written about it? [2]. BTW This doesn't mean it isn't degrading into some nasty stuff on its way out. 76.97.245.5 (talk) 03:23, 10 February 2009 (UTC)

is there a difference between: 1) water that has been frozen + melted 2) water that never was frozen?

Is there a difference between water that has been frozen and then allowed to melt, and water that never was frozen? I mean, if I prepare new water, by mixing hydrogen and oxygen, in two beakers, and leave one out but freeze the other one, then allow it to melt... once all the ice in the second beaker has melted and it has returned to room temperature will there be any difference between the two? (I don't mean from the longer amount of time the first one was out, ie microbes and such... if you want to account for this you can imagine that I prepare the solution to be left out the whole time by just later enough to nullify this effect). Thanks! —Preceding unsigned comment added by 82.120.236.246 (talk) 04:04, 9 February 2009 (UTC)

There is no difference in the water itself; it's all just H2O molecules and since it's a liquid they don't form structures. There could be a difference in the amount of air dissolved in it. --Anonymous, 04:32 UTC, February 9, 2009.

If you mix Hydrogen and Oxygen, you do not get water, you get Oxyhydrogen (also known as Knallgas). If you then add a spark, you will get a potentially dangerous explosion and some water vapor. If you start with chemically clean water, you can, in theory, freeze and melt it without permanently changing any of its properties. In practice, the more you handle it, the more likely you will add some contaminants. But to a first approximation, the water will not change. --Stephan Schulz (talk) 11:50, 9 February 2009 (UTC)

I read that there were 9 states of liquid and 18 states of solid for water, or something like that, among many other mysteries of water. For example, tests showed water to be H_1.5O. Water also forms a string of molecules, forming crystals when frozen, and this starts to break when melting, see also Mpemba effect. ~AH1^(TCU) 00:32, 14 February 2009 (UTC)

UFOs

File:DSC 0082.jpg —Preceding unsigned comment added by Bongoknyo (talk • contribs) 06:27, 9 February 2009 (UTC)

Hi.

I am the Investigator from Dr. J. Allen Hynek's Center for UFO Studies that was given the assignment to find the origins of the UFOs.

I am a former member of the American Intelligence Community, a currently non-practicing lawyer and the Chairman Emeritus of the Budget & Policy Subcommittee with the Drug Advisory Commission in Washington, DC. The Commission no longer exist, nor has it for many years. I am currently a Realtor Associate Broker who is licensed in MD/DC/VA.

Inasmuch as the British government will over the next 2 years release most of their previously held Secret [Top Secret] information about their ONGOING UFO investigations and the open knowledge from sources like Credo Mutwa, a Zulu Shammen and fluent speaker of English that his people have known about 24 different kinds of 'aliens' existing on this planet along with the recovery of numerous crashes and alien bodies from mountains in Kenya [and indeed thruout Africa], which were similar to those recovered in Roswell, New Mexico, I would like to provide an article that is very different from anything published under a single source.

I hope that it would not surprise you to learn that most modern US Presidents are not briefed about true UFOs and alien beings on Planet Earth, unless those alleged UFOs are intelligence gathering drones/aircraft/underseas vehicles, etc. that are already known to both sides of any particular operation.

I will not be disclosing TOP SECRET material, nor is there really any need to do so, considering what is collectively already known publicly.

Thanks.

Bruce Haupt —Preceding unsigned comment added by 68.166.173.176 (talk) 07:25, 9 February 2009 (UTC)

First of all, according to Ref Desk policy, I have removed your e-mail address from your posting.

Secondly, did you have a question, or was this just pure psychoceramica? -- Captain Disdain (talk) 08:38, 9 February 2009 (UTC)

I was not familiar with the term "psychoceramica", and in looking up its meaning -- "crackpot studies" -- I found the hilarious description of the subjects as "authors of particularly unsolicited manuscripts". :) --Sean 13:55, 9 February 2009 (UTC)

Oh, it's one of my very favorite words! -- Captain Disdain (talk) 02:23, 10 February 2009 (UTC)

Finally! I've been waiting for that proof for years. Just remember to cite reliable sources and that extraordinary claims require extraordinary evidence. --Sean 13:47, 9 February 2009 (UTC)

I must once again repeat my futile claim that "UFO" actually stands for "Unidentified Flying Object" and not "Aliens who control the United States and the World and Wikipedia through anal probes". *sigh* -RunningOnBrains 18:39, 9 February 2009 (UTC)

Well, considering that 99% of the public thinks "anal probes" when you say "UFOs", that claim is slipping into etymological fallacy territory. --Sean 22:57, 9 February 2009 (UTC)

Philosophical differences between Ayurvedic and Unani medicine

What are the basic fundamental difference between Ayurvedic and Unani systems of medicine.And can the wiki community identify any ayurvedic or unani practitioner who has been hounoured scientifically in the last 100 years.(Ramanathan) —Preceding unsigned comment added by 212.247.70.129 (talk) 09:56, 9 February 2009 (UTC)

Why are black people better dancers/athletes?

I always assumed this was more of a modern stereotype than anything else, but on reading the al-Jahiz article I saw that he was writing about it in the 9th century. So is there any scientific reason why black people have more "natural rhythm" than other races, and generally do seem to do better in sports? Has there been any research to see if this is actually true, or whether it is just a very old stereotype? Was Africa sufficiently more physically demanding/selective than Europe, Asia and the Americas to develop a noticeable difference so relatively quickly? Are these traits (if they exist) shared by Australian Aborigines, and if so, how? Thanks 86.8.176.85 (talk) 10:11, 9 February 2009 (UTC)

For atheletes you may want to look in the archives, I'm sure we've discussed it before. There are many factors which likely play a part, including the fact Africans are generally larger on average then many other others (particularly Asians) and that size is an advantage in many sports. There are some studies about it, e.g. [3]. I don't know about the dancing/rhytm thing though, I've never heard of it before and if anything, being small is often an advantage similar to in gymnastics Nil Einne (talk) 10:58, 9 February 2009 (UTC)

There's also likely a socio-cultural aspect to the athletics thing as well. For example, a group which has traditionally been at a disadvantage socioeconimically may see athletics as the only means for real advancement, and so may pursue athletic excellence to the exclusion of other forms of education or the like. As a contrast, members of the majority culture may "give up" sports for other careers which, while they don't pay as much, are much easier to break into and be successful at. --Jayron32.talk.contribs 13:14, 9 February 2009 (UTC)

For sports, there are two things going on here. First, there are indeed among some populations in Africa (which is a BIG place and you can't really justify lumping all "Africans" under one biological roof, mind you) which probabilistically will have certain members who are better physiologically equipped for certain sports. Note that this statement is a long way from saying "Blacks are better at sports"—we're talking about probabilistic genetics, we're talking about certain sub-populations, and we're talking probably about only certain sports. So what this means is that in certain sports, it's not improbable that, given the right conditions and access and etc., you'd see a higher percentage of star participants be African in descent. (It doesn't mean that there won't be people from other racial origins who won't individually be better or worse or whatever than individuals from Africa. Racial genetics is probabilistic and is about groups and has little to nothing to say about individuals.)

So that's the first thing. The second thing, which is HUGE, is the socio-cultural aspect. There was a time, for example, when Jews were known as the best boxers in the United States. How many Jewish boxers do you see today? Basically none. Why not? Because (professional) boxing is a sport that has real specific point of entry, and given other high-paying options most people will not opt to getting beat up for a living. When educational opportunities opened up for Jews, they took them, and now they become doctors, lawyers, businessmen, etc.—things that pay well and don't involve being beat up.

So what do we see for African-American populations, especially in the United States? We see that for the last 20 years the most prominent African-Americans are those in either sports or entertainment—something which is still true even today, in our post-Obama world, and was quite evident from the "guests" at the inauguration, even though for the last 10 years or so the number of visible Blacks in politics has increased quite a bit.

Now the real shame of all of this—which a number of academic commentators have pointed out—is that if you asked many Black children 10 years ago (I don't know if this has changed since then—it may have recently) what they wanted to be when they grew up, the answer is an entertainer or a sports star. Neither of which are viable options—only a small, small percentage of said children would ever be able to accomplish those as career paths. Coupled with that is that most modern American sports and entertainment culture is anti-intellectual to a hilt—especially Black sports culture—meaning that if you're dreaming of being a basketball player you're not also studying to be a lawyer. (Anti-intellectualism in Black culture is deeper than sports, mind you, and is wrapped up in the idea of what it means to "act White", but that's a different story for a different day.) So in the end, some commentators have argued, individual Black success in sports and entertainment has led to a decrease in the overall success of the Black population. For every Michael Jordan, you have 200 would-have-beens who have now no marketable skills and no love of anything but the ball. So they argue. (An interesting text in this regard is John Hoberman's Darwin's Athletes.)

Entertainment is somewhat different here, in that there is almost surely no biological component to it whatsoever. It's a pure-culture thing. Why do Blacks dominate the entertainment industry in the USA? Because whites think everything is cooler when Blacks are doing it—it's titillating and forbidden and "raw" and all sorts of other things that white culture isn't allowed to be ("white trash") and there are vulgar sexual overtones (both male and female) running explicitly throughout the whole thing. Whites love to fantasize about the Other, even if they often don't want to live or work next to them. It's a complicated thing, to be sure, made even more complicated by the fact of a Black president! --98.217.14.211 (talk) 14:48, 9 February 2009 (UTC)

That article singled out strength and nothing else and that is one thing Africans haven't excelled at, though for all I know they might at some time - there's more variation between them than the rest of the world put together. So I wouldn't put much reliance on it. As to personal experience the ones I've seen in Africa seem to have a hard time lifting just a single sack of cement between two of them though that could be due to any number of factors. Then again one of my uncles used to bend half crowns between his fingers as a party piece. Dmcq (talk) 16:30, 9 February 2009 (UTC)

Yeah, the socio-cultural thing is extremely relevent. Firstly with sports such as cricket (a sport with a history of Dukes, Princes and Sirs), the England Cricket Team is almost exclusively white, whereas the Kenyan Cricket Team are almost all black, yet British football teams have a very visible amount of black players. In swimming or diving they are hardly represented as most inner city schools don't have a swimming pool. As for the dancing thing, it pays to remember that most of the music that we see in the general (western) media, has it's genesis in old black musics such as jazz, blues, soul, reggae, etc. You don't hear of many black guys winning ballroom or waltzing competitions.91.111.108.123 (talk) 19:35, 9 February 2009 (UTC)

It also depends on the sport. In professional American Football, a person may look at the players and assume that African men are better. However, Samoans are overly represented. I don't remember the exact percentages from an article I read a few years ago, but it compared the racial background of NFL players to the percentage of adult males between 18 and 40 in the world. Asians had the lowest percent (near 0%) of adult men in the NFL. Whites were slightly lower than Africans. Samoans were by a large margin the most represented. Therefore, one could look at that tiny representation of sport and claim that Samoans are better athletes. Next, you can consider hockey or NASCAR racing. I think there was a black guy who was pretty good at turning left once, but it appears to be mostly a white thing. -- kainaw™ 19:52, 9 February 2009 (UTC)

As for dancing, there was a TV program ages back that examined ways kids learned how to move in various cultures. For most western cultures they found that they learned to move their limbs (arms and legs) in coordination. For African cultures they found that arms and legs were moved by separate beats. They didn't dig deeper into that, but went on into looking how girls learned to balance loads on their heads. 76.97.245.5 (talk) 21:37, 9 February 2009 (UTC)

Some African populations have been said to have more [4] fast twitch muscles. This has been claimed to be a reason African American basketball players can typically outjump caucasian athletes and outsprint them. Is this still accepted or has it been discredited? I have known some U.S. politicians and academics who have the view that folks from every continent are exactly equal in every mental and physical way, as if by definition, which seems of doubtful scientific validity, given that, say, Inuits and Kenyans have evolved to thrive in different environments. Edison (talk) 20:41, 10 February 2009 (UTC)

Different people in different cultures have great dancing culture, so I don't know how you can make a statement that Africans are better at it than everyone else. Regarding Kenyans and marathon. From an article I read a long time ago, actually not all (or most) Kenyans are good at it. There's a small subpopulation in Kenya that have the genetic factors contributing to being good at marathons, while the rest of Kenyans are "normal". Also, remember that Africans are more genetically diverse than populations of other continents.199.76.164.202 (talk) 12:36, 11 February 2009 (UTC)

Instruments that don't start at zero

If an instrument doesn't start at zero due to it not being calibrated properly or due to the way an experiment is carried out, what is it called when you set the initial reading given by the instrument to be the new "zero" --RMFan1 (talk) 12:26, 9 February 2009 (UTC)

When the instrument is a scale used for measuring weight, the word is "tare". In other settings, I use "zero" as a verb. --Scray (talk) 12:37, 9 February 2009 (UTC)

I'd say it's a "zero error" that you fix by "zeroing" the instrument. --Tango (talk) 12:41, 9 February 2009 (UTC)

I've always said "zeroing" but I've heard people say "nulling" and "balancing" too. I think the latter terms come from setting up a wheatstone bridge. In general, "calibration" would be a good word too - although calibrating most instruments requires adjusting more than just the zero point. SteveBaker (talk) 15:50, 9 February 2009 (UTC)

I have seen both "zero" and "re-zero" used as verbs in this situation. More specific terms may apply to certain instruments or experiments. TenOfAllTrades(talk) 17:28, 9 February 2009 (UTC)

General words like "set" or "adjust" may be used as well, of course. --Anonymous, 20:40 UTC, February 9, 2009.

For some instruments, like a CCD camera, the offset may be called a "bias", and correcting it may be called "debiasing". -- Coneslayer (talk) 20:47, 9 February 2009 (UTC)

When I worked in a testing lab, setting the zero point was called "zeroing", and was done before every measurement or series of measurements. "Calibration" was an extended procedure done once a year (or, for some sensors, after potentially-damaging incidents) that involved checking (and if needed, adjusting) the output at many different points along the full range of output. --Carnildo (talk) 01:47, 10 February 2009 (UTC)

deflection

i were looking for deflection .... I need avery detailed , clear theory , and the wide practicle use one ... i need to understand the basics of this theory , thank you ...? —Preceding unsigned comment added by Mjaafreh2008 (talk • contribs) 13:11, 9 February 2009 (UTC)

We have various articles on Deflection, are any of them what you want? If not, you're going to need to be much clearer about what it is you are talking about. --Tango (talk) 13:43, 9 February 2009 (UTC)

The most common use of the term is perhaps Deflection (engineering), which refers to the bending (or other deformation) of a material with force applied to it. Is that what you're asking about ? StuRat (talk) 18:29, 9 February 2009 (UTC)

yes ... iam talking about deflection in beams ... i need a deep ,step by step ,, thank you ..? —Preceding unsigned comment added by 94.249.43.138 (talk) 22:35, 9 February 2009 (UTC)

Well, let's start with the most basic theory:

1) Any force applied to an object (often called a stress), will result in some deflection or deformation (often called a strain). The amount depends on the material, it's geometry, and the location, direction, and magnitude of the forces applied.

2) There are three main ways a material can respond to a stress, with an elastic deformation (one that returns to it's original shape after the forces are removed), a plastic deformation (one that doesn't return), or fracture. Most material will undergo all three types of deformation, in the order listed. However, some will undergo far more of one than the other. As the names imply, elastics tend to undergo quite a bit of elastic deformation and plastics a lot of plastic deformation. Crystals tend to fracture with a minimal amount of either deformation. Metals do a bit of each stage.

3) See deformation (engineering) for the types which result from each force applied.

Now, as for figuring how much of deflection you will get for a given applied force, our deflection (engineering) article contains links to various calculation methods. StuRat (talk) 00:31, 10 February 2009 (UTC)

Frequency of Earthquake Waves

I am looking for the range of frequencies, in hertz, that can occur during an earthquake, both the S waves and the P waves. Thanks alot. —Preceding unsigned comment added by Jony big shoe (talk • contribs) 13:30, 9 February 2009 (UTC)

Seems like a good question, though I am no expert on the subject. I don't find this information in our articles on Earthquake, Seismology, P-wave, or S-wave. If this information is meaningful and missing from our articles, it would be great if someone (who has the information) could add it. --Scray (talk) 14:40, 9 February 2009 (UTC)

I changed the heading to reflect the specific question.

In 1978 Bruce Bolt wrote in Earthquakes: A Primer (W.H. Freeman & Co., ISBN 0-7167-0094-8): "In earthquakes the main shaking of the ground that is felt has frequencies of 20 hertz down to one cycle per second or even lower." Of course "cycle per second" is the same as "hertz". He does not comment on the frequencies of the different types of waves, but if they all originate from the same vibrations of the rocks at the focus of the quake, it makes sense that in any one earthquake they would have the same frequency. --Anonymous, 20:52 UTC, February 9, 2009.

Swarf

Metalworking term, refers to the chips / bits / etc. resulting from the process. Can't find origin of word. Acronym, or otherwise ? Rob&Sara Wilson (talk) 15:04, 9 February 2009 (UTC)

It's believed to be from ye olde English: [5]. Fribbler (talk) 15:16, 9 February 2009 (UTC)

Or from ye Old Norse, svarf: [6]. The OED is squarely on the fence about the matter. --Milkbreath (talk) 17:22, 9 February 2009 (UTC)

Presumably the two share a common origin, so shall we just say it comes from Proto-Germanic? Sufficiently vague that it's highly unlikely we're wrong... --Tango (talk) 00:41, 10 February 2009 (UTC)

Asking this question on the language desk may get you a better answer. This is the science desk. SteveBaker (talk) 02:45, 10 February 2009 (UTC)

Extraordinary claims require extraordinary evidence

While I understand what this expression means and don't necessarily disagree with it, it bothers me a bit because it begs the question, "What is an extraordinary claim?". If I believe in alien abduction, maybe I don't consider this to be an extraordinary claim because I believe that this sort of thing happens all the time. If both parties can't agree on what is "extraordinary", does this saying have any meaning at all? While I am a "skeptic" (I hate that term, too, for other reasons), this statement seems a bit illogical to me because it assumes that what qualifies as an "extraordinary claim" is agreed upon. 216.239.234.196 (talk) 15:28, 9 February 2009 (UTC)

It is personal. It means that if I see claim as being extraordinary, then I must see extraordinary evidence. If you don't see the claim as extraordinary, then you don't need extraordinary evidence. There is no need to agree on what is extraordinary. -- kainaw™ 15:37, 9 February 2009 (UTC)

I agree with the above, though to depersonalize it a bit, the general understanding is that the party receiving the claims/evidence is the one whose judge of extraordinariness matters. Alien abductions may be old hat to the guy who gets probed every third weekend, but they're not to the scientific community, and he'd better understand that if he wants anybody to care. — Lomn 15:41, 9 February 2009 (UTC)

Being probed yourself is pretty extraordinary evidence, so it's not surprising that he would believe it. --Tango (talk) 15:48, 9 February 2009 (UTC)

It is and it isn't. Memories are remarkably fallible, mental illness remarkably common. If I woke up tomorrow and thought I had been probed by an alien in the night, and could find absolutely no evidence of it, I would not necessarily trust that the event itself had actually happened. Similarly, if I started hearing voices that told me they were God, I'd probably suspect mental illness creeping in my head, if I was still rational enough to suspect such a thing. (The odds of it being mental illness seem much higher than actual divine communication with me, of all people.) --98.217.14.211 (talk) 18:00, 9 February 2009 (UTC)

Perhaps a rephrasing would help: "The evidence must be proportional to the claim" - so a slightly unusual claim requires slightly unusual amounts of evidence. If I say that "water is wet" you don't require any evidence at all. If I say that "there are two completely different colors that we call 'yellow'" - then you might need to be shown spectrograms to prove that. If I say that "I have a machine in my back yard that can travel at twice the speed of light" - then you're going to need some REALLY convincing proof. We simply say "Extraordinary claims demand extraordinary evidence" because Carl Sagan said that on a wildly popular TV show and he was a pretty cool dude and it's a handy short-hand for what we REALLY mean...which is that proportionality of claim and evidence is what is needed. As for what YOU believe - that's irrelevant to the discussion. If the people you are trying to convince say that your claim is extraordinary - then you'll need to provide them with extraordinary evidence if you want them to believe you. Claims of alien abductions are beyond "extraordinary" - so we're going to need a LOT of evidence...and right now, we have zero. SteveBaker (talk) 15:45, 9 February 2009 (UTC)

How about: "The weight of evidence for an extraordinary claim must be proportioned to its strangeness". But that's not a rephrasing, that's older than Sagan. I found it in Carl Sagan#Personal life and beliefs. It's attributed to Pierre-Simon Laplace. PrimeHunter (talk) 22:23, 9 February 2009 (UTC)

Judging the likelihood of a statement being true is often very subjective. Generally, the more things that need to be different from how we usually understand the world to be, the more extraordinary a claim is. For alien abduction to be true there would need to be aliens (perhaps not too unlikely, but far from certain), those aliens would have to have a way to get here (now that's pretty unlikely, either it requires our understanding of physics to be fundamentally wrong so they can travel faster than light, or it requires them to have taken an extremely long time to get here) and they would have to be interested in rather crude sounding experimentation (I guess not impossible) and they would need to have some way of hiding from all our telescopes, satellites, radio receivers, radars, etc (which is probably not too unlikely if they are capable of getting here in the first place). You multiply all those probabilities together and, even with pretty conservative estimates, you end up with a very unlikely occurrence. --Tango (talk) 15:48, 9 February 2009 (UTC)

If you're interested in a quantitative framework, Bayes theorem is applicable. If something seems highly unlikely given prior information, then any new evidence to the contrary must be very strong to overcome the prior. --Scray (talk) 15:59, 9 February 2009 (UTC)

I'd say we can apply some fairly objective means to determine how extraordinary a claim is. For example, is the claim consistent with current scientific theories, would it require an additional scientific theory, or does it go against existed widely accepted laws and theories ? Some examples:

1) I say blue food coloring and red food coloring combine to make purple. That's entirely consistent with all current scientific theories (provided the dyes don't react with each other). I wouldn't say any evidence at all is needed here, unless somebody disputes the claim.

2) I say trans-fats cause pimples. This requires a new theory as to how this happens. I provide the following theory: "Trans-fats are absorbed into the blood stream via the small intestines, travel to the sebaceous pores, where they are pulled out of the blood and excreted into the pore, where they solidify and cause pore blockage, AKA, pimples." Now this theory seems plausible, but some evidence would be needed to actually prove or disprove it.

3) I state that the universe is only 5000 years old. Since this runs counter to pretty much every branch of science, including astrophysics, particle physics (radioactive decay), biology (Theory of Evolution), zoology & botany (genetic drift rates & fossils), geology (plate tectonics, sediment deposition rates, erosion rates), archeology (ancient ruins), anthropology, linguistics, etc.; some really extraordinary evidence is needed to prove such a claim. StuRat (talk) 18:24, 9 February 2009 (UTC)

You can avoid the need for an objective opinion on what is extraordinary by always erring on the side of extraordinariness. After all, non-extraordinary claims should be very easy to provide conclusive evidence for. If an anal probe enthusiast says "water is not wet", I can simply throw a bucket of water on his head, his wetness will be obvious to him, and QED. Now when I say "extraterrestrials do not probe the human anus", he should be able to provide an equally unambiguous refutation. --Sean 18:31, 9 February 2009 (UTC)

Also, .196, you deserve a barnstar for being the first person to use the phrase "begging the question" correctly in all of human history. Bravo! --Sean 18:33, 9 February 2009 (UTC)

What? That's the common usage, not the tradition one... (note, I avoid using the word "correct"!) --Tango (talk) 19:03, 9 February 2009 (UTC)

I see the OP's post as the traditional circular reasoning usage: 1) "extraordinary claims require ...", 2) "your claim is extraordinary", 3) QED. I see how it could be interpreted in the "modern" way. --Sean 22:46, 9 February 2009 (UTC)

"it begs the question, "What is an extraordinary claim?"" seems like the "modern" way to me. --Tango (talk) 00:36, 10 February 2009 (UTC)

Here I was, planning to explain how 196 misused the phrase, and then I came across Sean commending him for it.

"Begging thw question" describes a logic flaw in which the question already assumes the answer. What 196 meant was that it "immediately leads to yet another question."

Tango is quite right, in that the phrase is more often used improperly than properly.

B00P (talk) 20:29, 10 February 2009 (UTC)

All of the answers above are pretty good, but there's another thing to consider here as well: when we say that extraordinary claims require extraordinary evidence, the underlying assumption of that statement is that people generally want others to believe them. So it's not that the extraordinariness of the claim somehow makes it require evidence, extraordinary or otherwise. You can claim whatever you want without a shred of evidence if you like, and a lot of people do. It's just that if you're going to convince other people -- well, sensible people, anyway -- that you're right, it's going to take more than your word, and the more your claim runs against the established and commonly accepted state of things, the more it takes to convince people. So whether you consider the claim to be extraordinary is irrelevant, because you can't convince anyone by telling them that they don't need any evidence, because you don't think it's all that weird -- and the whole point is to convince them. If you don't care about convincing them, then the point is moot. -- Captain Disdain (talk) 02:21, 10 February 2009 (UTC)

Many mainstream scientific principles or theories were once "extraordinary." These include the idea that the earth was many millions or billions of years old, that the Earth orbited the Sun, that humans evolved from previous species, that rocks could fall from the sky (Jefferson said in 1807 that it was easier to believe "that a Yankee professor could lie than that stones would fall from heaven," or that diseases are caused by little no-see-um germs. Rather than meekly accepting the truth of these propositions, extraordinary evidence was demanded. That is altogether proper. That such a demand is quite reasonable is shown by the success of furnishing the required proof and the resulting scientific and technical advances. Fans of Extrasensory perception, Unidentified flying objects from outer space, Perpetual motion, or Homeopathy are not being held to a higher standard than proponents of the above theories or phenomena. Thus N rays and Polywater failed to meet the scientific level of proof. They could not be replicated or were based on flawed observations. Edison (talk) 20:29, 10 February 2009 (UTC)

Those are all great examples - but the N-rays fiasco is perhaps one of the most sobering. The guy who claimed to have seen them was well-respected and even when 'due diligence' was done and his experiments repeated, too many people didn't believe that he could be wrong and misreported his results. That was not so much a lack of evidence for such an extraordinary claim - but more that there was insufficient skepticism about results turned in by a well-respected scientist. But it all fell apart when some genuine skeptic removed the wooden 'prism' through which the N-rays were supposedly being refracted and put it in his pocket while observations were being taken in a darkened room...and the experimenter failed to notice...or even to report 'unusual' results! I'd like to add the "Piltdown Man" example which was outright fraud. That was still being taught in schools as truth when I was a kid...let me make that more clear: Even though the hoax had been exposed in 1953 - it was still being taught as "true" as late as the mid 1960's. If you ever visit Piltdown (it's in the south-east of England) go to the "Piltdown Man" pub - they serve great beer. SteveBaker (talk) 03:27, 11 February 2009 (UTC)

Hmmm...I certainly didn't put as much effort in using the phrase "begging the question" as you guys did analyzing it and I'm not even sure if I completely understand the distinction between the two usages (or if there are even 2 usages - see below) however what I meant was that the expression "Extraordinary claims require extraordinary evidence" was based on a false premise. I'm not sure if that qualifies as circular since it doesn't really loop back and forth into infinity. It goes back to "what is an extraordinary claim" and just stops.

On a side note, I find our begging the question a bit confusing. The terms "contemporary" usage, "American English" usage, "British English" usage, "Traditional" usage and "Colloquial" usage are used. Are there 2 usages or 5? If 5 usages, what are the relationships between the 5? If 2 usages, under which usage do the 5 terms fall under? 216.239.234.196 (talk) 14:12, 11 February 2009 (UTC)

An "ordinary claim" would be accepted by scientists without demands for "extraordinary proof." If a scientist with a reputation for careful and accurate work reports some new measurement or observation, with results which are in accord with other published observations and with the currently accepted theories, it would likely just be added to the textbooks without everyone demanding to watch the experiment repeated. It would just be more ho-hum dustbowl empiricism. An example might have been if B.F. Skinner had reported the results of yet another schedule of reinforcement in an operant conditioning experiment after publishing hundreds of such papers. If he had reported that his rats started using sign language or communicating with him via ESP, it would have been questioned and other researchers would have demanded access to the special labrats to do their own testing. Edison (talk) 00:15, 12 February 2009 (UTC)

Anaerobe anatomy

Is it known whether anaerobic bacteria living near deep-sea hydrothermal vents have mitochondria similar to those in more "local" (terrestrial) life forms? (I hope my question makes sense... I don't have a firm grounding in microbiology.) Thanks, 168.9.120.8 (talk) 18:37, 9 February 2009 (UTC)

Bacteria do not have mitochondria. Mitochondria are the organelle responsible for aerobic respiration in eukaryotes and would not be involved in anaerobic behavior in any case. I don't know if eukaryotes living in that environment have specially adapted mitochondria or not. Dragons flight (talk) 18:46, 9 February 2009 (UTC)

Aha, I understand more than I did before, and (thanks to you, Dragons flight) I think I see the articles I need to fill in the gaps. Thank you for your prompt response, and have a nice day. 168.9.120.8 (talk) 19:55, 9 February 2009 (UTC)

stem cells

what is the stem cells ... i looked all over for it , without a clear answer , please help me ,thank you ..? —Preceding unsigned comment added by 94.249.43.138 (talk) 22:31, 9 February 2009 (UTC)

Try Stem cell Richard Avery (talk) 22:47, 9 February 2009 (UTC)

Alprazolam vs. Diazepam

Hello, I had a question. Is diazepam stronger than alprazolam? Thanks.Cssiitcic (talk) 22:51, 9 February 2009 (UTC)

What do you mean by "stronger"? Also, how would you want to compare them - the number of pills, the maximum tolerated dose, or some other measure? The number of milligrams alone is pretty meaningless. --Scray (talk) 03:31, 10 February 2009 (UTC)

Indeed, if you are concerned about the effects of the two drugs, or the actual recommended dosages of them, the only person who should provide that advice to you is a qualified medical professional. Do not trust random strangers on teh intrewebz to give you trustworthy advice over your own health. --Jayron32.talk.contribs 05:27, 10 February 2009 (UTC)

SorryCssiitcic (talk) 18:12, 10 February 2009 (UTC)

This article implies that alprazolam is about 10 times as potent as diazepam. This article suggests that overdosage of alprazolam is more dangerous. You could speculate reasons as to why this is the case. Axl ¤ [Talk] 08:59, 11 February 2009 (UTC)

February 10

How come this image says that the galaxy is impossible?

http://img87.imageshack.us/img87/6498/univerrrrsehg9jy8.jpg

In the bottom right frame, what does it mean when it says the galaxy is too large to exist according to current theories? —Preceding unsigned comment added by 70.171.234.117 (talk) 01:33, 10 February 2009 (UTC)

I'm not sure but if I had to guess, I'd say they mean we don't currently have a theory for how galaxies that large could form. --Tango (talk) 01:49, 10 February 2009 (UTC)

Those images are from the Hubble Ultra Deep Field. This webpage comments on the exact same galaxy you pointed to.

That galaxy--the one to the lower right of this image--is only 800 million years older ("younger" B00P) than the universe itself. That's quite surprising because for a long time after the Big Bang, no galaxies formed; even after all the hydrogen and helium cooled enough for stars to become a possibility, gravity still needs to bring the sparse gas clouds together to form stars. The first star probably formed 100 million years after the Big Bang--a significant fraction of this galaxy's age. Then enough stars had to form to organize themselves into large, gravitationally-bound galaxies. For this reason you'd expect the first galaxies to be small, because only after more stars form and those small galaxies combine are large galaxies possible. But the one in the photo is not only big, it has already stopped forming new stars! Exactly how the scientists know that I admit I can't tell, but it certainly doesn't seem young, which can't (yet) be easily explained by current theories. --Bowlhover (talk) 03:25, 10 February 2009 (UTC)

My bullshit meter is going off-scale here.

Our galaxy has 2x10¹¹ stars. Eight times that many would be 1.6x10¹². Our article "Galaxy" says: "Typical galaxies range from dwarfs with as few as ten million (10⁷) stars up to giants with one trillion (10¹²) stars,". Well if 10¹² is "typical" for a giant galaxy then I really very much doubt that 1.6 times more than that is "impossible". So I strongly suspect the language of that image is just over-hyped. Sure, it's a big galaxy...but I very much doubt "impossible" - or even particularly surprising. People are very fond of telling us that science regards such-and-such things as "impossible" (the flight of bees and the speed that dolphins swim are common examples) - perhaps because they think it's exciting for their readers. But that's rarely, if ever, actually true. Science just doesn't work like that. If the current theory of galaxy size says that there is a hard upper limit - then we find a galaxy that's 1.6 times bigger, we don't say "That Galaxy Is Impossible!!!" - we say "Our theory of maximum galaxy size is incorrect", then we start looking for a better theory. Hence it may be true to say that we have no good explanation for the sizes of some large galaxies - but it's certainly not true that science says it's impossible. But my best guess is that the author of that slide has one or more facts just plain wrong. This article [7] says that there are galaxies 100 times more massive than our own - so a mere 8 times heavier is nothing. We actually have an article about Abell 2029 - a galaxy that's 80 times bigger than the Milky Way.

SteveBaker (talk) 03:39, 10 February 2009 (UTC)

Did you read my post? That galaxy grew to eight times the size of the Milky Way within the first 800 million years of the universe's existence. For comparison, stars didn't even begin forming until 100 million years after the Big Bang. --Bowlhover (talk) 04:25, 10 February 2009 (UTC)

We had a little edit-conflict...so no, I didn't. OK - so the age of the galaxy is surprising given it's size - but it's size (in general) is not particularly amazing. SteveBaker (talk) 04:38, 10 February 2009 (UTC)

It just arises from the fact that the person who wrote the fact that something is impossible according to science doesn't understand science at all. Science would never say that something which is plainly observable is impossible. One of two things is going on: 1) The observation is flawed; for example that there is something distorting our image of the galaxy making it appear either older, farther away, or larger than it actually is (for example, some exotic sort of Gravitational lensing) OR 2) our current theories are flawed, at which point the current theories need to be tweaked. Science, thankfully, is flexible enough to deal with both of these situations. If the galaxy REALLY is that big, then it isn't impossible. That which actually exists is never impossible. --Jayron32.talk.contribs 05:24, 10 February 2009 (UTC)

I just gotta meet this Science character. Really smart AND flexible. Cool. --Scray (talk) 05:32, 10 February 2009 (UTC)

When a group of people are engaged in similar endeavors and who use the same general set of methods and principles, we use words like "Society", "Economy", "Education", "Government" and "Academia" to describe them as a group. It's really nothing to panic about. cf: "The Wikipedia Reference Desk doesn't answer homework questions". WP:RD would also be a cool dude to meet. SteveBaker (talk) 14:51, 10 February 2009 (UTC)

"Really smart AND flexible." I'd prefer Science as a girl. Zain Ebrahim (talk) 16:19, 10 February 2009 (UTC)

Would she have a really low-cut lab-coat? ...and could she say: "Is that a slide-rule in your pocket - or are you just glad to see me?"...then after you'd nod speechlessly she'd maybe say something like "You meet me behind the centrifuge and we we'll square some really BIG numbers...". That would be COOL...um - in a professional kind of way of course. SteveBaker (talk) 00:02, 11 February 2009 (UTC)

It is worth noting that some scientists have no qualms using the phrase "impossible" while discussing plainly observed phenomena in reputable journal publications:

• In Science (journal) - Generation of impossible cross-peaks..., "have been experimentally produced and detected, although such coherences are inconceivable in the normal theoretical framework";
• In Evolutionary Anthropology - The impossible coincidence. A single-species model for the origins of modern human behavior in Europe, ..."We are probably on safe ground in assuming that symbolic behavior and expression of this level of complexity would be inconceivable in the absence of highly structured language systems and brains closely similar, if not identical to, our own."
• International Symposium on Directions in General Relativity, Impossible measurements on quantum fields. "It is shown that the attempt to extend the notion of ideal measurement to quantum field theory leads to a conflict with locality, because (for most observables) the state vector reduction associated with an ideal measurement acts to transmit information faster than light. Two examples of such information-transfer are given..."

I am not judging whether these things are impossible, or if the empirical observations are flawed; I am merely noting that this omniscient Science character doesn't seem to mind using some sensational language every now and then to attract a few extra readers. Personally, I think it's pretty horrible that this "impossible" word-choice was used, and it's worse that it got past the reviewing committee. In regards to the original question, it's quite possible (probable, even) that some scientist actually used the term "impossible" while describing these galaxy observations. This Science character possibly has a few flaws every now and then... Nimur (talk) 06:53, 10 February 2009 (UTC)

The text on that poster has another significant over-simplification. It says "On September 3rd, 2003 the Hubble Space Telescope began pointing its camera at a small area in the night sky ... Hubble kept its camera pointing there for over 4 months, taking in all the light it could ...". From the 2003 date given, this is indeedreferring to the Hubble Ultra Deep Field, where data which was collected over 4 months between September 2003 and January 2004. However, the observations were not continuous, as the author implies - the HUDF was not even in Hubble's "continuous viewing zone". As our article explains, observations were made twice per orbit over two periods of about four weeks and six weeks respectively, and the total exposure time was about 1 million seconds or 11.5 days. As the author can't present this basic information accurately, I wouldn't take anything else they say on the poster too seriously. Gandalf61 (talk) 10:19, 10 February 2009 (UTC)

why are branched hydrocarbons more thermodynamically stable than unbranched ones?

I can't find a readable explanation anywhere. 199.111.188.173 (talk) 06:47, 10 February 2009 (UTC)

A C–H bond at a primary carbon (methyl group) is energetically different than at a secondary carbon (CH₂ group along a chain), and a tertiary (CH at a branch-point) is also different. In addition, there are steric differences (crowding of lots of atoms near each other) if you are branched vs being straight-chain. Seemsl like alkane or isomer might have info, but I haven't read them lately. DMacks (talk) 18:34, 10 February 2009 (UTC)

Genetic Modification potato

Which plants have genes that are suitable for GM potatos that are high yield and low energy waste?(more starch is present in edible areas than flowers etc.) I also need genes that require less water and fertiliser for growth. Tks. I need the info ASAP. tks —Preceding unsigned comment added by Invisiblebug590 (talk • contribs) 07:13, 10 February 2009 (UTC)

This sounds to me a lot like a homework question, forgive me if I am mistaken. If it is, next time, don't leave your homework to the last minute. And don't bother asking somewhere where we don't answer homework questions Nil Einne (talk) 12:15, 10 February 2009 (UTC)

Please do your own homework.

Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. SteveBaker (talk) 14:44, 10 February 2009 (UTC)

It sounds like a farmer asking for help, to me. StuRat (talk) 17:29, 10 February 2009 (UTC)

Except that for some reason, the OP needs the answer "ASAP". Anyone who is seriously contemplating genetic engineering should have plenty of time to be patient and make the right choices. In any event, perhaps the Genetically modified food article would be helpful to the OP? Simply Googling "transgenic potato" [8] also retrieves several potentially useful links. The starch article is a good place to start looking for plants that might have the desired characteristics. Drought tolerance discusses plants that adapted to arid conditions, and might be useful sources of "genes that require less water" (what you mean is "genes that allow the plant to utilize less water"). --- Medical geneticist (talk) 21:05, 10 February 2009 (UTC)

Yes - exactly. Farmers don't to genetic engineering. Seed potato producers might - but they know that the plural of potato is potatoes - and they most certainly don't decide what genes to splice on the basis of some geeks on Wikipedia! The 'ASAP' bit is also a bit strange for any kind of professional inquiry about something that would take years to get from laboratory to field. Hence, {{dyoh}}. SteveBaker (talk) 23:55, 10 February 2009 (UTC)

Curious shadow over Moon - cloud, or not?

Moon with shadow, one

Moon with shadow, two

Good day, RefDeskers. Today I have a query that's totally out of this world. Namely, last night I had a brief spur of photographing our own Moon because it was almost full, and the sky was quite clear. I just had a few minutes, but I managed to take among others, two photographs (at right) which show a curious shadow over the surface of our celestial companion. The span between both photos is eighteen seconds. They are unmodified and uncut of course. No tripod used, just put it down on a convenient staircase in my house. These are the only photos on which the shadow appears.

So, for the question that unavoidably poses itself (at least in my curious mind) - what is it? My mind refuses to accept a priori that it could be an Earthly cloud that got in the way.

Ideas, explanations, will be very much welcome. Feast your minds, and cheers! --Ouro (blah blah) 07:55, 10 February 2009 (UTC)

Could it be the February 2009 lunar eclipse? Pfly (talk) 08:45, 10 February 2009 (UTC)

Perhaps. I live in Gdańsk, Poland, so that could have _just_ been it. Yeah, that could be it (checked this image), maybe. --Ouro (blah blah) 08:51, 10 February 2009 (UTC)

Ah, I was on a long drive through the smoke haze from the 2009 Victorian bushfires, here in South-Eastern Australia. After sunset a dark orange full moon was rising directly ahead. I looked hard, because there did seem to be some unusual shading. That rather good diagram at Ouro's link confirms it as an eclipse, as I thought it might be at the time. Thanks!

–_⊥^{¡ɐɔıʇǝo}Noetica!^T– 09:21, 10 February 2009 (UTC)

A whisp of cloud? You should definately reject the notion that it could possibly be something so common and ordinary. I say you should claim you've photographed herds of wild chupacabras on their annual migration from Mare Imbrium to Mare Nubium, and sell the pictures to some supermarket tabloid. That's real science - and some money in your pocket. You could even start a cult. B00P (talk) 21:09, 10 February 2009 (UTC)

Can we add these images to the article's photo gallery? It says "NONE" and that should be fixed. ~AH1^(TCU) 02:32, 11 February 2009 (UTC)

They are contributed under CCA-SA3 - so yes! I think they could use some fairly drastic cropping first though. The location from which they were taken should be added to the image info so that the time stamp from the camera in the image Metadata can be corrected to UT. SteveBaker (talk) 03:13, 11 February 2009 (UTC)

Convince me that they are pictures of the eclipse. When I open them in two tabs in IE, blow them up full size, and switch between them, I see a blurry shape smaller than the lunar diameter move across from NE to SW in the upper part of the face. --Milkbreath (talk) 03:34, 11 February 2009 (UTC)

I'm doubtful on this too. Eclipses develop over much longer periods than 18 seconds and the shadow advances uniformly over the entire face. Also, depending on how accurate the clock on the camera is, Poland is at UT+0100 so the images were taken 22 minutes after the P4 point, i.e. the eclipse was already over by then. My money's on the chupacabras. Franamax (talk) 07:21, 11 February 2009 (UTC)

You can crop them any way you wish, guys. I don't think these are Chupacabras or Greys or anything on their daily stampede. Gonna get breakfast now... --Ouro (blah blah) 08:02, 11 February 2009 (UTC)

Can you check the clock on your camera to see how accurate it is? Franamax (talk) 08:27, 11 February 2009 (UTC)

I don't think it matters much whether the camera clock is accurate. According to [9] at Gdańsk, the sunrise is at 07:19 and sunset is at 16:41 on February 9th. Given the difference of UTC+1, this means 06:19 UTC and 15:41 UTC. The eclipse P1 was at 12:36:50 UTC and P4 was at 16:39:39 UTC. In other words it was before sunset for a big part of the eclipse. It's true that the end of the eclipse was after sunset but I doubt you would have seen much, remember it was a penumbral eclipse and even if it 90% at the greatest, that was over 1 hour before sunset. The image is cleaarly after sunset. Edit: Note according to [10] on February 9th the moonrise was at 16:45 i.e. 15:45 UTC so it must have been after then. Nil Einne (talk) 09:43, 11 February 2009 (UTC)

It's two minutes and eight seconds behind if you omit time zone difference. --Ouro (blah blah) 08:53, 11 February 2009 (UTC)

That pins it down then, it was 20 minutes after the eclipse ended. Maybe some bizarre atmospheric refraction effect, but I've never heard of such a thing. A wisp of cloud or plastic bag blowing past seem most likely. Sure is strange though. Franamax (talk) 17:22, 11 February 2009 (UTC)

I'd love to get to the bottom of this. Maybe it's the shadow of another planet or something that could have been between the Sun and the Moon at that time? I doubt it'd be a plastic bag blowing past, and I think that a cloud would have looked differently... --Ouro (blah blah) 17:49, 11 February 2009 (UTC)

Sure doesn't look like a cloud to me. I'm looking forward to looking at this photo in high-res when I get home. -Pete5x5 (talk) 18:14, 11 February 2009 (UTC)

It looks pretty cloud like to me. --Tango (talk) 18:27, 11 February 2009 (UTC)

Comparing the pictures on a better monitor, it looks like the shadow of a cloud. It moved quite a bit in 18 seconds! -Pete5x5 (talk) 21:23, 11 February 2009 (UTC)

Thing is, it's doubtful to me that it'd be a cloud, they usually move straight horizontally, and this shadow seems to have moved diagonally. That's my impression, at least. And, I believe that a cloud located straight in line between the camera and the Moon would have been illuminated by the light reflected by the Moon coming in the direction of the lens... and this does not seem to be the case here. --Ouro (blah blah) 21:44, 11 February 2009 (UTC)

Interestingly, the diagonal movement appears to be precisely opposite to the shadow track shown in [11], which I interpret as meaning that the penumbra moved from W/SW towards the NE. Is there such a thing as an atmospheric refraction effect? Seems to me that might move in the opposite direction to the penumbra. Franamax (talk) 22:19, 11 February 2009 (UTC)

How about simulating that moment using Celestia or similar software? Could that yield any results? --Ouro (blah blah) 07:05, 13 February 2009 (UTC)

If it is the shadow of a cloud, it wouldn't seem strange to me for it to move 30 arcminutes in 18 seconds. I've seen clouds move 1 degree (that's 60 arcminutes) in ONE second! ~AH1^(TCU) 00:20, 14 February 2009 (UTC)

I don't doubt it that clouds can be fast, but I'm more and more convinced that this isn't one. Unfortunately I haven't got the time to simulate the mechanics of the heavens accurately now, sadly. --Ouro (blah blah) 07:06, 16 February 2009 (UTC)

Medically qualified people with main contribution in physics\mathematics

David Alter comes to mind!As does William Gilbert.But do we have a comprehensive list of those who were medically qualified but made seminal contribution in physics or mathematics?(Ramanathan) —Preceding unsigned comment added by 212.247.70.129 (talk) 13:50, 10 February 2009 (UTC)

I don't think we have that kind of list, but one could use overlapping biography categories or clever googling to find them I think. The only one which comes to mind is James Lind whose medical experimental design in 1747 contained much of what is now standard experimental design in statistics and other sciences.

I think the other way round is much more common. For instance Adrian Kantrowitz, Joseph Rotblat and Thomas Rockwell Mackie all had an education in physics or math and went on to make contributions in medicine. EverGreg (talk) 14:08, 10 February 2009 (UTC)

Abū 'l-Walīd Muḥammad ibn Aḥmad ibn Rushd and Abu Ali Sina Balkhi both come to mind, but they are from such a distant era that the distinctions between "physics", "math", "chemistry", and "medicine" are all kind of blurry. The scholars of that era are all just some kind of scientist... Ibn Rushd described the retina, immune response, and defined kinetic energy 400 years before Isaac Newton. Abu Ali wrote over 100 medical treatises, and made contributions to thermodynamics, pre-Newtonian mechanics, and geology. Nimur (talk) 17:27, 10 February 2009 (UTC)

I was aware of this name when I asked the question but for the very reasons you adumbrate did not feel it right to consider him.Even a more striking example is Nasiruddin Tusi!And I remember reading that Pythagoras was a physician as well as was Galileo(Ramanathan) —Preceding unsigned comment added by 212.247.70.129 (talk) 12:03, 11 February 2009 (UTC)

Why is the death toll so high in the 2009 Victorian bushfires ?

California frequently has massive bushfires, but with lower death tolls. So, why the diff ? StuRat (talk) 19:27, 10 February 2009 (UTC)

It wasn't the size of the fires that caused the deaths, it was the unexpectedly high speed at which they travelled. Some described it as like a tsunami of fire. Dbfirs 19:36, 10 February 2009 (UTC)

And what caused that ? High winds ? StuRat (talk) 19:39, 10 February 2009 (UTC)

High winds blew embers about, these embers started new fires ahead of the main fire front. There was also a record heatwave, producing more dry fuel for the fire, and I believe that it had been unusually wet a few months ago, leading to lots of new growth which, once dried out by the heatwave, contributed more fuel. DuncanHill (talk) 19:50, 10 February 2009 (UTC)

Is the vegetation in Australia (Eucalyptus?) more flammable than that in California? Do weather forecasters and public safety officials give less advance warning of fire danger? Are people less prone to heed warnings and wait until the last minute to attempt to flee? Are there fewer evacuation routes? Edison (talk) 20:12, 10 February 2009 (UTC)

Yes: Eucalyptus is extremely flammable and can explode. Extreme droughts prior to the fires, then winds of 120kmh: [12]. Marysville, for example, was destroyed in a few minutes: [13] [14]. Official fire plans are to evacuate early or stay and defend. A number of deaths occurred when people fled at the last minute: perhaps changing their mind due to the ferocity of the blaze? Not a totally bad idea (a number of people saved their houses) but it seems the policy which will be reassessed. Various other contributing factors, also: [15]. Gwinva (talk) 20:31, 10 February 2009 (UTC)

There's tons of eucalyptus in coastal California. (Well, strictly speaking tons is a vast underestimate, of course.) Technically I suppose it's an invasive species; it was brought here I think a little over a century ago. But by now people like it and don't want to get rid of it, even if it were feasible. --Trovatore (talk) 22:41, 10 February 2009 (UTC)

There were reports that a number of the affected areas hit all-time highs before the fire started, including one area that hit 117 F (47 C), which is really scary hot. Most of the areas in California that are prone to fires never get quite that high. Dragons flight (talk) 20:59, 10 February 2009 (UTC)

Death Valley, California is, of course, one of the hottest places on Earth, but you're right that nothing much grows there so there's nothing much to burn. StuRat (talk) 21:11, 10 February 2009 (UTC)

Also, but more minorly, the fires hit populated areas a little more than usual - there were extentions of the fires in New South Wales and South Australia, but very few people live in the affected parts. - Jarry1250 ^{(t, c)} 22:12, 10 February 2009 (UTC)

When talking about temperatures, remember that official temperatures are always shade temperatures. The actual temperature outside, in the sun, was more like 60+ C (= 140+ F). (Hell, it was 50 C outside my place, and fortunately I'm well away from the nearest fire; not that we haven't been significantly affected by it, but I'm not complaining). Add that to hurricane-strength winds and incredibly dry vegetation and you've got a major problem. There's been a lot of speculation about why, understandably. That's why there's going to be a Royal Commission, to put all the facts on the table and make sure this can be avoided in future. The irony is that the confluence of extreme factors on Saturday may never happen again. -- JackofOz (talk) 22:40, 10 February 2009 (UTC)

You have to be careful when talking about temperatures in the sun — it's not always so clear what is meant. It's difficult to measure the air temperature in a sunny place, because the sunlight warms the thermometer, but I doubt that the actual air is that much hotter than it is in the shade.

Certainly you get hotter in the sun, because the sun also warms your body, but how much it warms it depends a lot on what you're wearing, and is not well captured by a single temperature number. --Trovatore (talk) 23:39, 10 February 2009 (UTC)

The dryer the vegetation you burn the better the chances of getting a firestorm from a fire.76.97.245.5 (talk) 03:50, 11 February 2009 (UTC)

One factor that certainly contributed to the death toll was that it happened on a Saturday, when people were at home. Had they been at work (in Melbourne for example, unless they worked close by), they'd have been safe. -- JackofOz (talk) 00:59, 13 February 2009 (UTC)

Be a good egg and answer this Q...

On Quincy, M.E. I saw them using chicken eggs as a bacteria culture medium. Are eggs still used for this ? If not, when did they stop using them ? I would think eggs would be less than ideal due to variations from egg to egg and them not being guaranteed to be sterile. StuRat (talk) 19:42, 10 February 2009 (UTC)

Eggs are still used as a cost-effective growth medium for certain cultures that need to be mass produced. The most common is probably in the manufacture of influenza vaccine (which is a virus not a bacteria, but you get the point). I would expect that eggs themselves would be unlikely to be used in first-world hospitals or labs these days, though there are a variety of culture growth media that are partially derived from processed and sterilized egg products. Dragons flight (talk) 20:17, 10 February 2009 (UTC)

Although not extremely detailed, Egg (biology) and Ernest William Goodpasture may be of some interest. cheers, 10draftsdeep (talk) 21:14, 10 February 2009 (UTC)

Following on Dragon flight's comment, this page has interesting details. --Scray (talk) 22:34, 10 February 2009 (UTC)

Yes - eggs are used in vast numbers on industrial scales for doing this. They are used for virus vaccine production because a virus needs a living cell's DNA/RNA in order to reproduce - they can't do it by themselves. On the other hand, bacteria can be produced in non-living material like agar (which is made from seaweed) because they can reproduce by themselves if they just have enough nutrients. I presume eggs are better than other living animals because they don't have to be fed or anything and they are easier to keep sterile. SteveBaker (talk) 23:49, 10 February 2009 (UTC)

do French and United Kingdom has same watts plugs?

Dear Sir/Madam,

Do I need only to the convert plug bceause French and United Kingdom has the same watts ??

In the wait for your response, —Preceding unsigned comment added by 82.120.236.246 (talk) 22:42, 10 February 2009 (UTC)

Do you mean volts? If so, yes, the whole of Europe (or maybe just EU) is 230V (+/- 10%) now. Watts depends on what current is being drawn - the maximum you can draw from a standard UK mains circuit is 13A (so 230*13=2990W), I expect France is similar, if not the same. --Tango (talk) 23:02, 10 February 2009 (UTC)

Volts and Hertz are mostly what matters - but you'll be OK in the UK and France. The plugs are different shapes but that's really all. The amount of power you can pull from the socket varies from outlet to outlet. In the UK, most house circuits are setup with thick enough wires and big enough fuses to allow you to pull 13 Amps (which - as Tango points out - is 2990 Watts). I doubt that France is the same - but it may vary depending on the age of the house. Basically - unless you're planning on running something HUGE like a refrigerator or washing machine - you'll be OK with nothing more than a converter plug. The worst that could happen would be that you'd blow a fuse in the house circuit. SteveBaker (talk) 23:38, 10 February 2009 (UTC)

Forgive me: there is not much use answering a tentatively phrased question with mention of Hertz (applicable to alternating current power sources) if you don't explain what that means. It is also a good idea to provide links.

For the basics concerning electricity, see Electricity. For power-supply characteristics in various countries, including voltage and frequency (for alternating current), see Mains power systems. For types of plugs in use, see AC power plugs and sockets, which covers most supplies. For DC plugs, see DC connector.

–_⊥^{¡ɐɔıʇǝo}Noetica!^T– 05:13, 11 February 2009 (UTC)

From this side of the pond, it seems surprising that France and the UK would have any consistencies. Has the Common Market been that effective? Edison (talk) 06:13, 11 February 2009 (UTC)

I don't think it has much to do with the common market. Most of the world outside of the Americas, Japan, Taiwan and evidentally a few Arab/African countries, has been for a very long time 220-240V with 50Hz (see this map File:WorldMap Voltage&Frequency.png). The EU has harmonised it to 230V with a big enough error to allow 240V but for most devices, the difference in voltage provided the voltage didn't vary too much from 220-240V was never a big problem AFAIK. Plugs have been more variable File:WorldMap PlugTypeInUse.png but the difference often isn't significant since you can use a passive converter in most instances. As mentioned by SB, the plugs used in the UK, as well as a number of Commonwealth countries are capable of providing 13 amps, as should the sockets, this is the only difference likely to be of significance since most other plugs don't support that high a current (the ones in NZ & Australia for example only support 10 amps) Nil Einne (talk) 08:31, 11 February 2009 (UTC)

Questioner, amongst all this learned stuff the answer is YES!. You only need to adapt the plug. I say this as someone who has travelled to France and used my English electrical equipment with no problems after using a plug adaptor. Richard Avery (talk) 08:47, 11 February 2009 (UTC)

Didn't we already say that? :-P Nil Einne (talk) 09:55, 11 February 2009 (UTC)

February 11

Magnetic perpetual machine

This is an idea for a perpetual machine, and it sounds theoretically plausible. Have two giant magnets placed high above the ground, with opposite poles pointing a common center. The magnets are fastened to the ground so they don't attract each other. In the gap between the magnets, have a horizontal magnetic rod. It's supported in such a way that it can rotate due to repelling/attracting interaction with the surrounding magnets. I would think the rod's rotation could go on forever...199.76.164.202 (talk) 03:58, 11 February 2009 (UTC)

The rotating rod will eventually slow down and stop due to friction and air resistance. - Eron^Talk 04:04, 11 February 2009 (UTC)

You are confusing different concepts. Lets say you do your experiment inside a vacuum chamber to eliminate friction. Lets say you succede and your rod keeps on spining for ever. It still wouldn't be a perpetual machine just as the Earth spinning around itself in space isn't a perpetual machine. —Preceding unsigned comment added by Dauto (talk • contribs) 04:15, 11 February 2009 (UTC)

I assume the arrangement is as follows, based on your explanation:

N           S
N           S
N           S
N 1rodXrod2 S
N           S
N           S
N           S

where N and S are the two suspended magnets' north and south poles respectively, and the rod (with ends labeled 1 and 2) pivots about X. Let's say the rod is pointing at the two magnets as in the diagram: you propose that one magnet will pull the "far end" towards it (N magnet pulls rod end 2), but doing so involves pulling that end away from the magnet it's near (S magnet). Magnetism weakens with distance, so you're requiring that a further (and therefore weaker) field will pull that end away from the closer (and therefore stronger) one. Nope. Okay, let's say the rod is parallel to the two magnet faces (rotated 90° about X in the diagram). Now each end of the rod is equally attracted to each magnet, so it just sits there motionless. Let's say the rod is actually a magnet, with end 1 North and end 2 South. That will quickly rotate away from the above diagram and stick with the rod rotated 180° (rod end 1 North pointing at South magnet, etc) and stay there.

What you really need is a way to change the magnetic properties of the external field and/or the rod (as a magnet) over time. If you can get the rod ends to continually reverse their N/S identities, or have a constant rod magnet and keep swapping the external poles, you will get rotation. The rod will move to make its poles as attracted to the external magnets, but then either the rod or the external magnets change identies, which makes the rod swing back the other way. And so on. Unfortunately, that takes some energy (either physically moving some permanent magnets around or alternating an electric current in some electromagnets, but it's doable. Not quite perpetual motion though, but fun to experiment with. You can buy "electric motors" in many hobby stores. DMacks (talk) 04:18, 11 February 2009 (UTC)

The question makes no sense. Having two magnets "fixed to the ground" with opposite poles facing each other in no way lessens the attraction of the poles. Their height from the ground is likewise irrelevant. Edison (talk) 06:10, 11 February 2009 (UTC)

Er, I think the point is that the two magnets do not physically move towards each other. Axl ¤ [Talk] 10:26, 11 February 2009 (UTC)

Unless you can extract usable energy from it, it isn't a perpetual motion machine. Any machine will keep moving if there is nothing to stop it (that's one of Newton's laws). --Tango (talk) 13:51, 11 February 2009 (UTC)

To explain what Tango just aluded to, the problem is not creating "perpetual motion" (i.e. movement that will happen forever), its creating a "perpetual motion machine", that is something that will do useful work forever. There are any number of ways to set something in motion essentially forever. However, in order to be an effective machine, you would need a way to use that motion to power something else. Any attempt at extracting energy for another application from your perpetual motion device will either slow it down, or require you to add energy to it to keep it going, thus negating its perpetual motion. --Jayron32.talk.contribs 20:18, 11 February 2009 (UTC)

Thanks for the answers everyone. 128.163.80.152 (talk) 18:13, 12 February 2009 (UTC)

how to make a magnet

hey people- im in the 6th grade and in the science fair anyone know how to make a magnet???? i am gonna try making a magnet then proving points of the north and south poles of it. any help???? —Preceding unsigned comment added by 76.112.80.95 (talk) 23:28, 10 February 2009 (UTC) Copied from Talk:Magnet - Eldereft (cont.) 05:06, 11 February 2009 (UTC)

No homework or science fair questions, but I'll give you a hint: dry cell + iron rod + wires = Electromagnet. B00P (talk) 05:48, 11 February 2009 (UTC)

Bleh, it's trivial to find directions for making a magnet and the 6th grader would still need to make it, so I see no problem in explaining how. Dragons flight (talk) 05:52, 11 February 2009 (UTC)

You can make an electromagnet by winding a wire around a piece of iron many, many times and connecting it to a battery. When I was a kid we used to do this with iron nail(s), speaker wire, and a 9v lantern battery, all things available for cheap at any hardware store. Take a thick nail (or nails) wrap in wire from end to end several layers thick and connect the battery. Do it right and you'll be able to lift paper clips and other small objects. Make sure the nails are iron though, aluminum nails would be worthless for this. Dragons flight (talk) 05:52, 11 February 2009 (UTC)

Some ways to make a permanent magnet: 1) Take a piece of steel, like a needle or other iron/steel object and stroke it several times with a strong magnet. 2) make a solenoid with a great many turns of insulated wire. Place a piece of steel in it. Pass a large DC current (like from a 6 volt lantern battery) through it. 3) Do 1 or 2, but use a compound such as Alnico or Neodymium which makes a powerful magnet. 3) Align a piece of iron or steel with the Earth's magnetic field. This field varies with longitude and latitude, in both the horizontal and vertical dimensions.A dipping needle and magnetic compass can be used to determine the best orientation. Tap the piece of ferrous (iron) material hard and it will become magnetzed. Note that there is a health hazard with powerful magnets: If someone swallows two powerful magnets, they may trap a section of gut leading to Peritonitis and death (Who would swallow one, let alone two magnets?) Edison (talk) 06:01, 11 February 2009 (UTC)

Edison, we don't give medical advice here. ;-) Axl ¤ [Talk] 10:29, 11 February 2009 (UTC)

The magnet article doesn't have as much as it should about this. The easiest way to magnetize a long straight piece of iron, like a nail, is to repeatedly stroke it along the pole of another magnet. The strokes should always be in the same direction. The end of the bar that last leaves the magnet during a stroke should develop the opposite pole as the magnet pole.

This can only create a rather weak magnet. To create a stronger magnet, a bar of iron can be heated, placed between the poles of a magnet, allowed to cool in that position, and hammered as it cools. It works best to heat the iron to its Curie temperature of 1418° F (770° C), which is red hot, but lower heats also work The end of the bar toward the magnet's North pole will become a South pole, and the end of the bar near the magnet's South pole will become a North pole.

The strong permanent magnets you can buy are made of special types of metal alloys such as alnico, ferrite, or neodymium and are made by melting the metal and allowing it to harden between the poles of a strong magnet, and while it is still soft stretching it or rolling it like bread dough in the direction of the magnet's poles. Good luck with your project. --Chetvorno^TALK 07:12, 11 February 2009 (UTC)

Be careful with making electromagnets. If you don't make enough windings of the wire around the metal core, you'll effectively be short-circuiting the battery. You need really fine, insulated wire and you should be thinking of hundreds of times wrapped around the core - not (say) a dozen or so. If you do short it out - then depending on the type of battery that can heat it up enough that the contents boil and then explode. If you hook up your electromagnet and feel that the battery is starting to get warm - disconnect it immediately. By far the simplest way for a 6th grader to make a magnet is to take something SMALL like a pin or a needle and just stroke it from one end to the other (don't rub it back and forth - start at (say) the eye of the needle - stroke the magnet down to the pointy tip - then lift the magnet away from the needle and start the next stroke next to the 'eye'. It shouldn't take many strokes to make a magnet strong enough to use as a compass needle. The best way to do that is to stick the needle through a 1/2" slice of a wine-bottle cork and float it in a small amount of water. SteveBaker (talk) 21:44, 11 February 2009 (UTC)

Doesn't the magnetization take place pretty quickly? I would expect that once the current reaches its maximum you are about done. It should not be necessary to leave the current flowing long enough for the wire and battery to heat up, in order to magnetize a piece of steel (as opposed to making a piece of iron into an electromagnet). I agree with Steve that in winding an electromagnet it takes LOTS of turns (hundreds) to get enough wire in the circuit that it has resistance enough not to look like a short circuit to the battery. Edison (talk) 00:04, 12 February 2009 (UTC)

A medical emergency that could lead to a diagnosis of anemia

I am writing a story in which a character collapses and loses consciousness, and as a result of underlying conditions becomes diagnosed with, and is treated for, anemia. Having had some experience with medical jargon but not actually knowing very much about medicine (I'm an ESRD patient with anemia), I want to come up with something that is plausible and passes the acid test, so to speak. I don't know any doctors; I've spoken to a few people with medical knowledge and they've suggested things like severe tachycardia or some other heart emergency, but I'm not sure if anemia can actually cause any of these things. A little help? JuJube (talk) 05:15, 11 February 2009 (UTC)

Did you try your own link to anaemia, it seems to contain all the info you're asking for. Richard Avery (talk) 08:40, 11 February 2009 (UTC)

Here's 41 potential candidates. There's a few exotic oddities on there if you want a "House MD" type story. Fribbler (talk) 09:32, 11 February 2009 (UTC)

Except lupus...it's NEVER lupus. SteveBaker (talk) 20:12, 11 February 2009 (UTC)

And since it's never lupus, it's ok to use your lupus textbook as a place to stash drugs. Except one time it actually was lupus... -Pete5x5 (talk) 05:40, 12 February 2009 (UTC)

The most dramatic disease which causes the symptoms you describe, is Paroxysmal cold hemoglobinuria. It is a rare disease, which most often affects children, but young adults may also be affected. It is an autoimmune disease, which is triggered usually by a trivial viral infection. In the classical case, the auto-antibody reacts with the P antigen (which is present in at least 99% of the population). In a severe case, within a few hours, a large percentage of the patient's red blood cells may be lysed. This is of course a medical emergency, the patient will be severely ill, his serum will be brown due to free haemoglobin, and he will be febrile and possibly mentally affected (reduced consciousness, confusion, collapse). The disease may be fatal, but the autoimmune reaction itself is usually self-limiting, and the auto-antibodies tend to disappear within a couple of weeks. Regrettably, by that time the massive hemolysis may have permanently damaged the kidneys, and caused kidney failure. --NorwegianBlue ^talk 21:37, 11 February 2009 (UTC)

How does an anaemic ESRD sufferer not know any doctors? Surely you'd come into contact with plenty managing your illness. If not, you probably should! Mattopaedia (talk) 00:58, 13 February 2009 (UTC)

I know doctors; I just don't understand the terms they use, usually. And I don't think ESRD would lead to a medical emergency involving collapse and unconsciousness. I've been in situations where I couldn't breathe due to pulmonary edema, but the lack of consciousness wasn't sudden. x_x JuJube (talk) 07:52, 13 February 2009 (UTC)

Engine silencer

OK I'm just throwing ideas around and I'm a little bit over my head when it comes to modern engine technology, but I was wondering how feasible it would be, and what might be possible when it comes to quietening engines/fans, such as are used on the Skycar or other hover/flight machines. I've googled some information and been reading up on engine noise suppression, and I've come to the conclusion that active noise control is unfeasible unless you can somehow control exactly what kind of sound the machine makes. Would something like a mixer (engine) be possible on a hovercraft-like machine? I'm actually thinking of something more like an Avrocar, more a craft capable of hovering with stability at relative hights than a jet or a water-skirting hovercraft.

There is some discussion here about the same problem, though it doesn't seem that there is a solution. Another thing is clear is that there are four possible sources for noise: the motor driving a fan (if there is a fan), the parts of the fan itself, the turbulence at intake, and the turbulence at exhaust. The intake noise isn't an issue if the fan is part of the outside chassis (as with the Avrocar), and the exhaust turbulence can't really be avoided (unless a mixer can be used, but I'm not really sure how it works). The fan I guess would have to be aerodynamically shaped with incredible precision so as to eliminate drag, though that leaves the actual moving hub. The engine seems to be the biggest problem so that's why I've tried to limit this to a question about silencing engines!

So is there anything I've missed here? And does anyone know of anything else that can be done, or possibly an alternate way in which such a machine can be designed in order to reduce noise, or allow noise-reduction techniques? Thanks. 219.102.220.90 (talk) 05:36, 11 February 2009 (UTC)

I thought of an easier way to ask this question. How might one go about silencing an X-Jet? I haven't been able to find any video clips of it with sound, though I'm quite sure it's noisy given that it is powered by a special Williams [Williams F112|[WR19-9]] turbofan. 210.254.117.186 (talk) 13:03, 11 February 2009 (UTC)

Missile range

Recent news reports discuss Iran's launching of a satellite into orbit. They also discuss fears that "it could lead to the development of longer-range ballistic missiles" (The Economist 07Feb).

How does this work? If you can put something into orbit, doesn't it mean you can already shoot it all the way around the earth? How much longer range can you get? Wouldn't you already be able to fire a heavier payload to a shorter distance? Franamax (talk) 05:42, 11 February 2009 (UTC)

I'm far from an expert on these sort of things but it's worth remembering that getting something into space into some sort of orbital distance isn't actually a great distance. According to [16] the satellite in question is only orbiting at 155 miles+ which is the range of the missile used to launch it (as we would somewhat expect). Obviously that's largely straight up and requires you to achieve escape velocity, and other things so somewhat different from simply shooting a missile to travel inside the atmosphere to hit a target but it depends how far you mean I presume. For example, according to Intercontinental ballistic missile "the apogee (halfway the midcourse phase) is at an altitude of approximately 1,200 km". Clearly quite a big difference from what Iran has achieved. Beyond that, I presume there's quite a lot of additional complications like making sure it doesn't break up upon reentry and accurately hitting a target as well as achieving the elliptic orbit necessary in the first place. In theory I guess, once you've gotten something into orbit you could in theory deorbit it and attempt to hit a target, but it's not much use if it's easily destroyed, liable to breakup by itself, be rather imprecise and will take too long to reach your intended target Nil Einne (talk) 07:57, 11 February 2009 (UTC)

Those are some of the things that "development of ballistic missiles" consists of: first you have a device that gets to orbit, the next step is to give it deorbit capability, harden it against re-entry, and develop an accurate targeting system. That's what a ballistic missile needs to do, after all. 88.112.63.253 (talk) 08:32, 11 February 2009 (UTC)

The preceding is wrong in several ways, as noted below. No "de-orbiting" is necessary. See Ballistic missile. Edison (talk) 23:48, 11 February 2009 (UTC)

Just reaching an apogee of 1200 km is less than what Iran achieved; if you steer the rocket used for the orbital launch straight up, you reach more than 6000 km. Besides what 88.112.63.253 said you also have to think about the payload of the rocket (if you have only a primitive nuclear weapon, it might be too heavy for your rocket) and how much time one needs to prepare a launch (the time is generally shorter for solid rockets, but they have usually lower specific impulse, requiring a larger rocket for the same payload and "dry" weight fraction). Icek (talk) 08:48, 11 February 2009 (UTC)

Yes - my understanding is that their rocket put a four pound object into orbit. That object (if it had suitable retro-rocket thrusters) could be brought down anywhere along it's orbital path - and they could probably use a polar orbit to hit any location in the world. But with only a 4lb payload (minus retro-thrusters, minus radio gear and computer stuff, minus battery/solar panel) - that's not really enough. However, if you look at the power of the rocket needed to get a 4lb object into orbit - and imagine that with a non-orbital ballistic trajectory and with a small nuke on board - then the range would as stated. The slightly worrysome part is that this was a multi-stage rocket. Mastering multi-stage rocketry allows for the possibility of using (say) four rockets firing together as a first stage - with the second and third stages being as now. THAT might be enough to get a nuke in orbit. SteveBaker (talk) 19:52, 11 February 2009 (UTC)

The orbital height attainable is not at all the same as the range of a missile. The V-2 had a range of 320 km but could not put anything in orbit at all. It takes a more powerful engine to obtain a given orbital height than to deliver a payload to a point the same distance away on the ground. A missile which could place an object in orbit could deliver the object to the opposite side of the world.Per Ballistic missile it is not at all necessary to place the object in orbit and then fire a retro rocket to de-orbit and hit the target. The warhead is accelerated in the boost phase, then it just coasts in a sub-orbital ballistic path until it encounters the atmosphere and reenters. So if they could orbit a four pound object, they should be able to get a heavier object to the re-entry location. Edison (talk) 23:50, 11 February 2009 (UTC)

During our propulsion system testing, it was a common joke that to get to orbit, all you had to do was "turn left at the top", but of course this was totally ignoring the physics and engineering considerations... Nimur (talk) 09:15, 12 February 2009 (UTC)

Degree of Relatedness

What is the degree of relatedness between two children of an incestuous relationship between a half-sister and half-brother, I feel like it's 0.75, but I'm not, any ideas? 169.229.75.128 (talk) 07:11, 11 February 2009 (UTC)

The half-siblings have a degree of relatedness of 0.25, so from the unrelated 0.75 of the siblings the children have degree of relatedness of 0.375 (as they have a degree of relatedness of 0.5 for unrelated parents) and add to that the 0.25 -> the degree of relatedness is 0.625. Icek (talk) 08:52, 11 February 2009 (UTC)

IceK, why should relatedness be additive ? And more general: how did you come to the 0.375, and about what children/siblings are you talking in which part of your answer ? I did also some reading into the matter, and I'm at the moment totally confused because every article and every paper uses his own definition of "relatedness" or "incestness" or whatever. There is a famous method called "path counting", but I have at the moment found two different methods for it which arrive at different numbers for the same relationship... What a mess. A little help of a statistician and/or mathematician could be needed, as I am really curious now to know the proper calculation. TheMaster17 (talk) 09:23, 11 February 2009 (UTC)

Coefficient of relationship might help.76.97.245.5 (talk) 10:07, 11 February 2009 (UTC)

No, it doesn't help. By the way, it's in a really bad shape, concerning style and form. It even adresses the reader personally. And as I said: the definitions of relatedness differ even in publications, and in a way that I cannot make sense out of it. So a short, unscientific, badly written wikipedia article doesn't help, no. TheMaster17 (talk) 12:29, 11 February 2009 (UTC)

It's 0.125. According to the table in Coefficient of relationship, half-siblings have a degree of relatedness of 0.25. Each received 1/2 of their alleles from the shared parent and for each gene there would be a 1/2 chance of the same allele being transmitted. 1/2 * 1/2 = 1/4. Full siblings share 1/2 of their alleles, so the children of the consanguineous couple would likewise share 1/2 of their parents' alleles. 1/4 * 1/2 = 1/8. Thus, two children born to a half-brother and half-sister would share on average 1/8 of the alleles transmitted from the shared grandparent. --- Medical geneticist (talk) 15:57, 11 February 2009 (UTC)

I still have trouble quiet grasping this. So there are three generations here, right? The first has a woman, call her A, who married a man B and a man C. A and B had a female child D, and A and C had a male child E. Second generation then is the half-siblings D and E. Their degree of relationship (r) is 0.25. Then they have two children F and G, the third generation. The Coefficient of relationship page points out it's "assuming no consanguinity" in its calculations of r. Yet it does get into the issue of half-siblings, saying they have an r_m of 0.5 and an r_p of 0, since there is no chance of receiving alleles from their different fathers. The 0.5 and 0 average out to 0.25. But in the example here, where the half-siblings have children, wouldn't you want to track the r_p of the two first generation men, rather than just making them zero in the second generation? Sure, the half-sibling D has r=0 with C, and E has r=0 with B, but the grandchildren F and G have some degree of r with A, B, and C, right? Unless I'm confused (which is likely!), User Medical geneticist calculated the degree of relationship between the grandchildren F and G as 0.125 based on the chance of sharing alleles with grandmother A (um, I think--maybe I understood). But wouldn't they also have a chance of sharing alleles with both grandfathers B and C, unlike the half-siblings? Wouldn't that make the degree of relationship something higher than 0.125? Most likely I just don't quite grasp the way these calculations are done. Pfly (talk) 17:10, 11 February 2009 (UTC)

Another issue that arose in my calculations: The questions sounds to me as if the "base generation" of the calculation should be the cosanguine parents. As "normal" (so, not cosanguine) parents produce children with a relatedness of 0.5, I am sure that cosanguine parents must have children with a higher relatedness. But I'm unable to calculate this properly, and nothing I have read specifically mentions this problem and, more general, the problem of "shifting the base generation". And what is also puzzling me with the answer that Medical geneticist gave: He arrives at a relatedness of 1/8 for grandparents to grandchildren, while the article coefficient of relatedness gives 1/4 for non-cosanguine grandparents-grandchildren... How can a cosanguine line of descent have grandchildren which are less related ? Something must be wrong here. 132.252.149.100 (talk) 17:22, 11 February 2009 (UTC)

I looked through this page, which does the "path counting" thing. If I understood right, the grandchildren would each have four direct paths of descent. The grandmother having two paths through the two half-siblings. The linked page above says in calculating collateral relationship (the grandchildren to each other), "No individual must occur in the same path more than once." So, if I have it right, that would leave three descent paths, A->D->F, B->D->F, and C->E->F (using my letters above, and the same for grandchild G). The calculation is supposed to be the sum of (1/2)ⁿ, with n equal to the number of steps in the paths, in this case 2. So, each of the three paths would be (1/2)² = 1/4. And 1/4 + 1/4 + 1/4 = 3/4. So the degree of relationship between the grandchildren is 0.75? Again I am likely misunderstanding all this. Pfly (talk) 18:01, 11 February 2009 (UTC)

I also stumbled upon that "path-counting" thing, but wasn't able to do it properly. But for the value of 0.75: At least it's bigger than 0.5, which would be the relatedness of non-cosanguine sibblings, according to our article and some web pages. But I think as long as nobody shows up here who has experience with this kind of calculation (or we find a very neat page with understandable examples for cosanguines), we are not going to sort this out for ourselves, because we cannot distinguish which of the numbers is the "right" one. Any population geneticist who's good with numbers here ? TheMaster17 (talk) 19:21, 11 February 2009 (UTC)

Doh! The dangers of quick "back of the napkin" calculations... In my initial response I was trying to assess the proportion of alleles shared by the siblings. I took the 0.25 number from the table and multiplied by 1/2 to get 1/8, but this doesn't seem right. Others seem to be using a quite different calculation (the "path counting" thing) so we must be talking about very different things. Back to the drawing board! --- Medical geneticist (talk) 22:26, 11 February 2009 (UTC)

I agree with Icek's answer of 0.625. StuRat (talk) 22:32, 11 February 2009 (UTC)

Icek calculation is right (good explanation too). the answer is r=5/8=0.625. Medical geneticist also had correct reasoning but he forgot to add 1/2 (tha any regular brothers have in common) to the 1/8 that he calculated. 1/2+1/8=5/8. Dauto (talk) 02:23, 12 February 2009 (UTC)

This question was cross posted at the mathematics help desk, where I posted my answer of 9/16. As I seem to be in the minority in my opinion of the answer, I'll go ahead and explain my reasoning. The following is a sort of "brute force" approach to the problem... it is easier with a diagram (but I'm too lazy to scan it in).

Suppose you have grandparents A, B, C. A and B have child D, A and C have child E, and D and E have children F and G. Given a gene in F, we want the probability of that gene being present in G.

Half of D's genes come from B. 1/4 of D's genes come from A and are not present in E. 1/4 of D's genes come from A and are present in E.

Half of E's genes come from C. 1/4 of E's genes come from A are are not present in D. 1/4 of E's genes come from A and are present in D.

In F, we find: 1/4 of genes come from B then D (which I will denote: B->D). 1/8 from A->D are not present in E. 1/8 from A->D are present in E. 1/4 from C->E. 1/8 from A->E are not present in D. 1/8 from A->E are present in D.

So if we choose a random gene in F, then:

• 1/4 chance B->D, in which case 1/2 chance of being present in G.
• 1/4 chance C->E, in which case 1/2 chance of being present in G.
• 1/8 chance A->D, not present in E, in which case 1/2 chance of being present in G.
• 1/8 chance A->E, not present in D, in which case 1/2 chance of being present in G.
• 1/4 chance being present in both D and E, in which case 3/4 chance of being present in G.

Adding up the results, we find 9/16 chance of being present in G.

Eric. 06:48, 12 February 2009 (UTC) —Preceding unsigned comment added by 131.215.158.184 (talk)

Thank you Eric, this way I understand the answer and also the way you arrived at it. And even the question as you formulated it seems better to me: What is the chance of finding the same gene in both sibblings? Sometimes it's only a matter of getting the question clear. :-) "Degree of relatedness" is too abstract to have a clear meaning outside of context. I hope the OP is satisfied with this, but I really doubt he is still following, looking at the time it took for a result. TheMaster17 (talk) 10:41, 12 February 2009 (UTC)

The only problem with Erics explanation is the fact that it is wrong because it fails to take into consideration the increased homozigoteness of F and G (being the offspring of a partially incestuos couple). The degree of relatedness is intended of as a measurement of the likely homozigoteness of a possible offspring between two persons (neglecting gender and age barries that could make an offspring unlikely or impossible). From that point of view, two people with a higher then average homozigoteness (F and G) will have a higher degree of relatedness then they would have had we chosen to define relatednes simply as the likelyhood of sharing a randomly chosen gene (as Eric did). To be more specific, lets say that A,B,C, and D are different alleles for a gene. If two individuals share all their genes (identical twins), they could have for instance alleles (AB) and (AB) with only 50% chance of homozigoteness for a hypotetical offspring (forget about the fact that an offspring would be impossible). Homozigote twins would have alleles (AA) and (AA) and would be even more related to each other then normal twins. Unrelated individuals could have alleles (AB) and (CD) with 0% chance of homozigoteness of the offspring. Using a somewhat arbitrary normalization which assumes that unrelated individuos share no genes at all and are completely heterozigotes for simplicity, we get the following values for relatedness between all possible combinations: (AB)+(CD)->r=0, (AB)+(AC)->r=1/2, (AB)+(AB)->r=1, (AA)+(BC)->r=0, but also (and that's where Eric went wrong) (AA)+(AB)->r=1, (AA)+(BB)->r=0, and (AA)+(AA)->r=2. Take that into consideration and repeat Erics reasoning and you will get the slightly higher value of r=10/16=5/8 in average, which is the correct result originally obtained by Icek through much simpler methods. Dauto (talk) 19:16, 12 February 2009 (UTC)

I see. Now that I've read the article on coefficient of relationship I understand the definition of relatedness you describe. Under this definition the "3/4" in my table above should be changed to a "1", giving 5/8 as the answer. I won't hesitate to add that this definition is a bit counterintuitive, as the degree of relatedness of an individual with itself could be anywhere from 1 to 2, depending on the homozygoity of its genome; and in particular we must make assumptions about the homozygoity of the grandparents A, B, C before we can draw conclusions about the relatedness of F and G. But I can hardly complain if this is the accepted definition used in literature. (And I agree that it is easier to calculate than the definition I was using.) Eric. 131.215.158.184 (talk) 22:27, 12 February 2009 (UTC)

I agree that the definition as I used leads to degrees of relatedness larger then one. But that's the best (only?) way to take into consideration the possibility of homozygoity. Your other point about having to make assumptions about the grandparents is true, but we will always have to make assumptions (that they are not related for instance) about the grandparents, no matter what definition we chose for relatedness. —Preceding unsigned comment added by Dauto (talk • contribs) 00:45, 13 February 2009 (UTC)

It's not the greater-than-one I don't like (a number is a number whichever way), it's the variability from one individual to another: perhaps I am more closely related to myself than you are closely related to yourself. There is also the fact that the definition uses the (somewhat complicated) notion of alleles at a locus, and that the result of the calculation depends upon the diploidity of the genomes in question, and so will not hold in a species with slightly different inheritance rules. And although with either definition, we must assume that A, B, and C are unrelated to each other, with this definition we must additionally assume that A, B, and C have degree 1 relatedness to themselves -- an assumption that is not necessarily true and not easy to test for. But this is merely the mathematician within me being whiny about elegance (this is what happens when people leak over from the math reference desk): what really matters is which definition is more useful in real-life biology, and frankly the standard Sewall Wright's definition is more useful than the incorrect definition I was using. So oh well. Eric. 131.215.158.184 (talk) 04:22, 13 February 2009 (UTC)

Will Ultraviolet A or B rays kill the vibrio cholerae bacteria?

If you expose the cholerae bacteria to ultraviolet light (A and B)

- will it kill the baceteria? Thus will you be able to clean water for drinking purposes if you can expose it to these two electromagnetic rays.

- which one of the two will be more effective?

- what intensity of lightrays and for how long must the water be exposed to it for the bacteria to be killed?

Nuuskierig (talk) 11:15, 11 February 2009 (UTC)

This is obviously a homework question. I expect the answer is within a textbook in which your syllabus is based on. Please read up on ultraviolet germicidal irradiation for question 1. There is a useful table at Ultraviolet#Subtypes which should help in answering question 2. Question 3, I don't know. --Mark PEA (talk) 19:19, 11 February 2009 (UTC)

See Ultraviolet#Disinfecting drinking water. You may also find Ultraviolet#subtypes and Water absorption useful. For question 3 you can probably get some idea by looking up the operating parameters of commercially available ultraviolet water sterilizers. 152.16.144.213 (talk) 01:58, 12 February 2009 (UTC)

Was William Harvey realy the first person to describe blood circulation?

The entire Ayurvedic medicine is based on the foundation of blood circulation and I note that circulatory system is quite well described in Caraka samhita.(Ramanathan)

Other physicians, notably Ibn al-Nafis and Michael Servetus, had suggested the idea of the circulation of the blood before William Harvey. Harvey's contribution was to put the idea on a firm scientific footing, through experiment, vivisection and quantitative observations. Our article on Ayurveda talks about the role of "channels" - "tubes that exist within the body and transport fluids from one point to another" - but that seems a long way from an unequivocal description of a circulatory system. It seems equally consistent with the Galenic view (commonly held in Europe before Harvey) in which "venous blood was thought to originate in the liver and arterial blood in the heart; the blood flowed from those organs to all parts of the body where it was consumed". If you can point to a clear description of the circulatory system in the Charaka Samhita then please give more details, but remember that it is important not to let our interpretation of ancient texts be filtered and coloured by our modern scientific knowledge. Gandalf61 (talk) 13:05, 11 February 2009 (UTC)

The last bit about using modern interpretations filter our understanding is crucial here. The concept of circulation is not just that blood flows through the veins. That's pretty obvious if you've had a serious cut. Circulation discusses the role of the heart in distributing blood and managing its oxygenation in two closed loops (see systemic circulation and pulmonary circulation). That's a pretty specific claim about how the fluids move functionally and what their physiological significance is—not some vague notion of circulating blood (which, again, is obvious).

People often go very wrong in finding "precursors" first by misunderstanding what the key element of the "discovery" is (either through ignorance or because it has been overly simplified in modern discussions of it) or by reading into vague and poetic texts a specific scientific meaning that is only apparent if you already know what the final outcome is meant to be. (Similarly, vague notions of transmutation of species are not the same thing as a systematic discussion of how biological evolution works, and vague notions of inherited properties are not a systematic discussion of the mechanisms of genetics.) --98.217.14.211 (talk) 13:38, 11 February 2009 (UTC)

CIVIL ENGINEERING

I HAVE HEARD THAT THERE ARE CHEMICALS AVAILABLE WHICH CAN MAKE A LEAKING CEILING (MADE UP OF CEMENT AND CONCRETE) ABSOLUTELY WATER PROOF WHEN APPLIED FROM THE BOTTOM SIDE.

IS THIS SO?

IF YES, THAN WANT TO KNOW THE COMMERCIAL NAME.

ANY OTHER WAY TO PREVENT THE SAME PROBLEM? —Preceding unsigned comment added by Saurabh85 (talk • contribs) 12:36, 11 February 2009 (UTC)

That doesn't sound like a good idea, because the water will still be there, and it will accumulate within the ceiling. You have to figure out where the water is coming from and seal it off. --Milkbreath (talk) 12:54, 11 February 2009 (UTC)

Also consider:

• Water is 1 tonne per cubic metre.
• Damp / moist concrete will effect affect the thermal insulation properties.
• When the reinforcement rods have lost strength due to rust, the ceiling will just crash down.
• If the stuff freezes the entire structure is likely to disintegrate.
• Dampness will spread to the walls (supporting or not). --Cookatoo.ergo.ZooM (talk) 14:16, 11 February 2009 (UTC)

What you may have heard about was a primer like Kilz [17] or a waterproof paint like Perma-White [18]. Neither of these will counteract a leak. They are for treating the after effects of a leak i.e. water stains and mold/mildew. You'll have to fix the leak first. Then you can treat the ceiling from the bottom to prevent the damage from showing through. If it's the ceiling of a rental apartment and you are the tenant inform the apartment manager that it needs fixing. In a condo contact the owner above you. If it's your own house check your water, drain and heating pipes for leaks. (Plumber) If it's under a bathroom check the tiles and caulk around the tub or shower. See if your chimney may be sweating. Check your roof for leaks, particularly around plumbing vents, chimneys and skylights. Use a hose and see if you can re-create the leak on a dry day. (Better and safer: Get a roofer to do that. Make sure you use adequate safety measures when you do it yourself.) See if your gutters or downspouts have cracks or leaks. Check and seal places where wires enter your house. The water might be creeping in along those. Other possible causes: missing air gap in a brick wall above, faulty siding, improperly installed insulation, condensation. If you can't find and stop the leak, there are companies that specialize in leak detection and remedy. They cost a pretty penny, but beat having your ceiling cave in on you. Good luck. 76.97.245.5 (talk) 15:17, 11 February 2009 (UTC)

Depending on the thermal insulation (or the lack thereof) this may also be condensation. Poorly insulated concrete as you may find in garages and utility buildings may act as a "bridge" as the heat is dissipated to the outside.. The concrete slab may become quite cold and cause water vapour to condense on the surface. A pellet pallet of styrofoam panels may be all you need. --Cookatoo.ergo.ZooM (talk) 18:28, 11 February 2009 (UTC)

what happens in the fractioning column (in the lab) as ethanol-water mixture boils?

While carrying out fractional distillation, apparently. I'm reading something about a "ring of condensate" but I am unsure what this exactly looks like. What happens in the column when the ethanol-enriched vapor is boiling versus just the pure water? Or perhaps just at the inflection point? 199.111.188.130 (talk) 13:14, 11 February 2009 (UTC)

Not an answer to your question, but there was a thread here a while ago which may be of interest. See Phase diagrams for mixtures of ethanol and water.. --NorwegianBlue ^talk 21:48, 11 February 2009 (UTC)

Wireless invention;Bose or Marconi!

Does teh popular belief in India that it was Jagadis Chander Bose and not Marconi who should be credited with wireless invention carry currency with teh wiki community?(Ramanathan) —Preceding unsigned comment added by 212.247.70.129 (talk) 14:05, 11 February 2009 (UTC)

We have an article Invention of radio which discusses the contributions of Bose, Marconi and others. Algebraist 14:11, 11 February 2009 (UTC)

Our article List of persons considered father or mother of a field notes that Alexander Stepanovich Popov, Lee De Forest, Guglielmo Marconi, Jagdish Chandra Bose, and Nikola Tesla have all been credited as the inventor. Algebraist 14:14, 11 February 2009 (UTC)

De Forest as "inventor of radio" is absurd, since radio predated his work. Popov as "inventor of radio" is absurd since detecting lightning storms is far from "radio." Marconi took the inventions of others and used them to send signals effectively, so is plausible. Note that Thomas Edison demonstrated high frequency electromagnetic wave transmission and detection in 1875. He called it Etheric force and published his results. Scientists erroneously dismissed it as induction. David Hughes sent Morse code signals by electromagnetic waves in 1879, but his results were erroneously dismissed at the time as induction. Invention is usually an incremental process. Edison (talk) 23:38, 11 February 2009 (UTC)

"...Invention is usually an incremental process," ... and to ascribe credit to a single individual is always going to be based on a subjective evaluation of which innovation(s) were the crucial ones. Nimur (talk) 09:19, 12 February 2009 (UTC)

Migraines and Auras

Please note: I am not after medical advice, I know precisely what they are I am just shooting the breeze with some biologically-educated peoples on here

If one suffers from a Migraine with an Aura attached, is it feasible that one can intentionally recreate the mental sensations and visual hallucinations in ones mind from memory and thus re-trigger the aura and even the migraine?

Well, I know its feasible cause I can do it, but does anyone want to hypothesise with me as to how the biological side of it works? Again, this isn't medical advice, pure curiosity, I know the policy :)

Regards, SGGH ^ping! 15:18, 11 February 2009 (UTC)

Does aura (symptom) have any useful info about this ? My own thoughts are that, just as an epilepsy attack can be triggered by flashing lights of a certain frequency, which then send signals to the parts of the brain which cause the epilepsy malfunction, certain stimuli, either external or internal (thoughts), can also send signals into the parts of the brain which causes the migraine malfunction. I wonder if this could lead to a biofeedback-like way to prevent migraines, by not thinking of the things which trigger a migraine. Unfortunately, trying not to think of something often has the exact opposite effect. Perhaps there is something safer to think about (like the old relaxing brook). This would be consistent with typical advice for migraine sufferers to avoid stress. StuRat (talk) 15:32, 11 February 2009 (UTC)

The aura article unfortunately doesn't have too much on self-trigger. Interestingly enough, the trigger for one I had last night was the thought of someone taking 9/something in a cricket match!!! Weird. Sometimes I wish I could work out where these things come from, many of the hallucinations seem as if they are memories or something. It's odd to describe. SGGH ^ping! 15:43, 11 February 2009 (UTC)

Here's someone who could trigger his migraines by playing sports. Not quite the method you were thinking of. [19] Yet another Discover article. My memory seems to have a separate department for those:-) 76.97.245.5 (talk) 16:40, 11 February 2009 (UTC)

It seems someone who can trigger an aura by thought might be of value to a catscanner somewhere! SGGH ^ping! 20:16, 11 February 2009 (UTC)

You're not the only one to get a migraine at the thought of cricket: [20] Gwinva (talk) 00:12, 12 February 2009 (UTC)

Eyeglass prescription

I've just had an eye test and my prescription has a weird squiggle for the left spherical component. It looks like an infinity symbol, or possibly "cs" (written very quickly). From context, I would guess it means zero (it's certainly a fairly small number), but according to our article zero is usually written either "0.00" or "Pl". It almost looks like it says "05", but it certainly isn't 5 and some of the other values are a half and they are written very clearly as "0.50". Any ideas what it means? --Tango (talk) 15:45, 11 February 2009 (UTC)

I say, can you scan it for us to see, perhaps? It'd help a great lot. Cheers, Ouro (blah blah) 18:05, 11 February 2009 (UTC)

I might be able to tomorrow if necessary. --Tango (talk) 18:15, 11 February 2009 (UTC)

Well, I'm one who prefers to see what he needs to describe or elaborate upon rather than having to recreate it in thought, so it'd be better, but if someone helps you just based on your description then don't strain yourself, Tango. --Ouro (blah blah) 18:22, 11 February 2009 (UTC)

If no-one has answered by tomorrow afternoon (UTC), I should be able to go and scan it - there is a computer room with a scanner not too far away. --Tango (talk) 18:32, 11 February 2009 (UTC)

Until then, here is my attempt at tracing the symbol in MS Paint. It's not perfect, but it gives you a decent impression. File:Eyeprescription.JPG --Tango (talk) 18:37, 11 February 2009 (UTC)

Do you have a digital camera? If so, turn on the "Macro" setting and you should be able to get a decent photo of it. SteveBaker (talk) 19:30, 11 February 2009 (UTC)

Clever clogs... Alright, try this: --Tango (talk) 19:48, 11 February 2009 (UTC)

It absolutely looks like an infinity symbol to me, yeah. No idea if that means anything in opthalmology, but it seems fairly clear. ~ mazca ^t|c 20:15, 11 February 2009 (UTC)

If the ophthalmologist has diagnosed astigmatism this may refer to a lens with cylindrical chracteristics. --Cookatoo.ergo.ZooM (talk) 18:08, 11 February 2009 (UTC)

Yes, I have an astigmatism. There are three columns on the prescription, sphere, cylinder and axis (well, there's prism and base too, but they're blank). The symbol I'm talking about is in the sphere column. The cylindrical component is -0.50 with an axis of 180. I'm trying to work out what the spherical component is. --Tango (talk) 18:15, 11 February 2009 (UTC)

Call the doctor who wrote the prescription, and/or ask the optometrist who is going to make your eyeglasses (or sell you contact lenses). A bunch of invisible people on the internet are going to be less than helpful. --LarryMac | Talk 18:28, 11 February 2009 (UTC)

I have great faith in the ability of ref deskers to be helpful! If no-one has come up with an answer by the time my new glasses are ready to collect in a week or so, I'll ask while I'm there. --Tango (talk) 18:39, 11 February 2009 (UTC)

I guess we need some optical guru (which I am not). ∞ (and that is a capital ∞, for those who need spectacles!) dioptries on your left eye would mean a focal length of 0m, so I guess that your left eye does not require any correction by the spherical properties of the lens but is solely tweaked by the -0.50 dpt of the cylindrical focus. As the axis is given as 180deg, all the power is on the vertical axis and 0dpt are on the horizontal one. So the lens has to provide "distortion" in but one direction (as a cylinder does), which means that there is no "spherical property" required.

On the right eye, conversely, you have 175deg and require some correction on the horizontal axis, ergo a bit of "sphericity" of -0.25dpt is needed.

As stated above, somebody who knows more about optics than I should be able to give a better answer. --Cookatoo.ergo.ZooM (talk) 21:21, 11 February 2009 (UTC)

A focal length of 0m is not zero correction; it's infinite correction. Not physically realizable (at least in any way I can imagine) and would hardly be useful in eyeglasses anyway. But who knows; maybe for some reason optometrists write infinity when they mean zero (not necessarily totally irrational — maybe the infinity symbol is harder to misread, and of course it's not good for anything else anyway — obviously this is pure speculation on my part). --Trovatore (talk)

Yes, I was puzzled by that, too. As Trovatore, I assumed it to be some opthalmological standard. --Cookatoo.ergo.ZooM (talk) 22:12, 11 February 2009 (UTC)

These sites (and others) said it's used for "plano" or "flat" lenses [21] [22]. How you would get that to display the other two characteristics beats me, but I'm no optician either. 76.97.245.5 (talk) 23:42, 11 February 2009 (UTC)

Those sites describe a flat lens as having an infinite radius of curvature (which is true), but it seems odd that they would measure curved lenses in terms of power (in dioptres - metres^-1) and flat ones in terms of radius of curvature (a distance). Maybe opticians are just odd... --Tango (talk) 23:49, 11 February 2009 (UTC)

I found a UK commercial website, extreme-eyewear, that has a section explaining "your eyewear prescription". It says that "sphere can be one of three values" and that the first is "Zero (also written as 0.00, -, ‘left blank’, and the infinity sign: ∞)." To judge by that, each optometrist has his own way of expressing "no correction" for sphere, and one of them is the infinity sign that is obviously what's on your prescription there. A sphere of infinite radius has a plane suface, I guess, Euclid notwithstanding. --Milkbreath (talk) 00:33, 12 February 2009 (UTC)

Fantastic, well found! Thank you. --Tango (talk) 14:01, 12 February 2009 (UTC)

Checking that loading of wells in SDS PAGE is comparable or whatever

We want to do a western blot to check acetylation levels of histones in cell cultures treated differently. We want to find the percentage of acetylated histones relative to total histones. Thus our options inculde a) probe with antibody for acetylated histones, strip membrane of antibodoes and reprobe for all histones and b) pipette each sample into the gel twice, making a mirror image, cutting the resulting membrane in half and probing each half with the two different antibodies. I favour the stripping method but my supervisor favours the other method. I would like advise. Thanks in advance.

Your supervisor is probably right. Stripping is often hit-or-miss, and it's only something you want to get into if it can't be avoided. Incomplete stripping of the first primary antibody may give you an inappropriately weak signal when you reprobe. Overly-stringent stripping may lead to decreased overall signal or increased background. A side benefit of running parallel gels (or at least cutting the membrane in half) is that your total time from gel to results is shorter, since you can probe for both species at the same time.

One more thought — you and your supervisor may have already discussed this, but it's worth noting that the affinities of different antibodies can vary quite significantly. If you're trying to get actual percentage-acetylation numbers out of a (semi-)quantitative western, you're going to have to run a lot of standards in parallel with your experimental samples. The antibody for total histones may be more sensitive (for example) than the acetylated-histone antibody. In that case, even given 100% acetylation, the acetylated-histone signal would be weaker than the total-histone signal. If the acetylated-histone antibody works better, your raw data might well suggest a nonsensical greater-than-100% acetylation fraction. (Running two gels instead of one will also free up extra lanes so you can run concentration standards....) Hope that helps, TenOfAllTrades(talk) 23:32, 11 February 2009 (UTC)

mirror paint?

So I have this great, huge, antique mirror I just got for my teeny, tiny room. It really helps. However, the back is chipped in a few places, leading to ugly spots. Is there anything I coudl paint on the front that's "mirror paint" (ie looks like a mirror)? The other choice is to put a smaller mirror at a particular spot in front of it, but I think a small cosmetic solution as above would be better... —Preceding unsigned comment added by 82.120.236.246 (talk) 19:13, 11 February 2009 (UTC)

Nothing you could possibly do on the front of the mirror would ever look right. The reflective layer of the mirror is behind the glass - you'd have to get behind the mirror to fix up the bad spot. There are places that will re-silver a mirror - but the process is quite expensive and usually limited to antique mirrors. May I suggest a google search for "Resilver mirror"...the most promising hit I saw was [23] - but there were many more. The good news is that assuming there are no chips in the glass, this process will have your mirror looking like new. SteveBaker (talk) 19:27, 11 February 2009 (UTC)

You can´t possibly resilver a mirror yourself. Apart from the cost it is highly dangerous, as you work with mercury (?) and other nasty chemicals. You may not even be able to purchase the required chemicals without a relevant license.

The only inexpensive solution I can think of would be to purchase a sheet of acrylic mirror (you can use a very fine jigsaw to fit it to the frame) and insert the thin acrylic plate into the existing frame, maybe even on top of the existing glass. Bear in mind that acrylic is comparatively soft, so you need to take excessive care not to scratch the surface, when working it or when cleaning it. The original surfaces are typically protected by some stick-on foil which you peel off when the work is finished. When "sawing" acrylic sheeting work very slowly and gingerly, as hasty work inevitably leads to a crack in the sheet.

Of course, you can have it resilvered by a professional, but that will a costly option. It may be "cheaper" to have the glass plate replaced. --Cookatoo.ergo.ZooM (talk) 20:26, 11 February 2009 (UTC)

An old trick when an antique mirror has a bit of the silvering scratched off is to stick a little piece of aluminum foil behind the mirror, shiny side facing the room. Instead of a black spot you will then see a spot which blends in better with the rest of the mirror. A 2006 article said that the minimum charge for resilvering an old mirror was $20, and that the cost was about $15 per square foot. It advised that it was cheaper to just buy a replacement mirror unless it was odd shaped, antique, etc. In the 1830's mercury was used, but apparently modern methods use silver nitrate and other chemicals.If it is a really valuable antique, you might wish to get the advice of an expert as to whether the original appearance is more valuable than resilvered "like new" appearance. One company which resilvers mirrors says that one pint of each of the four chemicals they use costs a total of $120, and they even provide the website of their supplier. Edison (talk) 23:19, 11 February 2009 (UTC)

Little spots can easily be disguised with foil behind. For larger spots, you can attach a small mirror behind. (Find a handbag or make-up mirror slightly larger than the hole. Glue it to the back of your mirror, or for a less permanent measure fix with strong double-sided tape.) It adds a strange depth if you look closely, but with a standard glance it's fine, and much better than a large spot. (I've got an old mirror "fixed" in this way, as advised by a furniture restorer, who considered re-silvering too costly for most situations; it works well.) By the way, do you mean slightly antique (i.e. just old) or really antique? If it's valuable, seek the advice of an expert. Very old mirrors used actual silver backs (hence their dark appearance) and spotting is caused by deterioration of the silver, rather than the chipping or wearing away of the backing. Gwinva (talk) 23:45, 11 February 2009 (UTC)

If you are in Europe you can get sticky (um: "adhesive") foil that you can stick on the front. [24] I bet we also have something like that in the US. I would recommend not buying it here [25] because a price difference between Euro 8.29 and $150.00 has to include a golden parachute somewhere in the delivery chain :-o - 76.97.245.5 (talk) 00:03, 12 February 2009 (UTC)

Alternatively you could find a pattern or drawing you like and etch it into the back~, based on the holes you already have in the reflective layer. You could then paint over what has been removed in color or gold. 190.17.201.142 (talk) 00:33, 12 February 2009 (UTC)

If you stick a new mirror to the back of the damaged antique mirror where there are flaws, please consider using a front surface mirror, such as the ones available from Edmund Scientific or [American Science Center[. The silver on the front of the patch mirror reduces parallax. Edison (talk) 06:31, 12 February 2009 (UTC)

CO detector going off

This is not really a science question, but a health one. Here goes:

The CO detector in my apartment keeps going off. It's placed in the hallway between the kitchen, which is closer to the door as well as a window, and the bedrooms. I'm not sure air circulates well there, but I also don't see it as a sink of sorts either. But obviously CO gathers there after cooking, because a couple to a few hours after all the oven fires are turned off, the alarm often goes off.

What can I do to fix this problem? Thanks in advance. Imagine Reason (talk) 20:11, 11 February 2009 (UTC)

Relocate your detector if possible, move something to allow the air flow, or get your oven checked because it could be going off because there is an actual problem? SGGH ^ping! 20:14, 11 February 2009 (UTC)

Yeah; a healthy oven really shouldn't be producing any appreciable levels of CO. It's very much worth getting it tested. ~ mazca ^t|c 21:17, 11 February 2009 (UTC)

Never assume it's a false alarm. CO is very difficult to detect so I doubt you have any way to be certain there isn't actually a problem. Air your house very thoroughly and call someone in to check the oven. --Tango (talk) 21:26, 11 February 2009 (UTC)

Carbon monoxide is odorless and colorless, so your detector is going off for a reason. A smoke detector, now those things are a pain in the ass if you do a lot of horrible cooking like I do. But your CO detector is very important and you should really get that checked. Livewireo (talk) 21:46, 11 February 2009 (UTC)

Our article "Carbon monoxide detector" points out that "CO detectors can be placed near the ceiling or near the floor as CO is very close to the same density as air." This means that CO is not "gathering" anywhere. If your detector is working right, an abnormally high level of CO exists in all the air in your house. You should be scared, and you should have your equipment checked. I would call my local fire department's non-emergency number, if it was me, to get advice about what to do next. --Milkbreath (talk) 23:24, 11 February 2009 (UTC)

Our article gives a wrong connotation about the uniformity distribution CO. CO produced by heating apparatus will rise with the warm air and will thus be "concentrated" although the low molecular weight will ensure it diffuses away effectively. My source is here. 152.16.144.213 (talk) 01:41, 12 February 2009 (UTC)

"Keeps going off"? Does that mean it stops? Check the battery in your monitor: some go off intermittently when the battery is low (to tell you to change it). If the battery is fine (or the monitor is mains operated) you should certainly have your appliances checked. If you have any doubts, get an expert in asap. Gwinva (talk) 23:32, 11 February 2009 (UTC)

Your CO detector likely has a test setting like a smoke detector does (probably a test button or switch) which you can press to see if its working. You should do that after making sure you have a fresh battery. If the test is successful and the battery is fresh, call the landlord and have them check out the oven sooner rather than later. A safety sheet from my workplace advises that smoke detectors' air intakes be vacuumed out annually. I don't know if it applies to CO detectors but it couldn't hurt. In the meantime, you can and should increase air circulation when you cook by using the vent and opening windows so the place is properly ventilated. When you cook, you should leave the cooking vent (and/or windows) on afterwards because quite a few ovens do those self-cleaning cycles (they can last a couple hours) which burns off any cooking residue by heating to a high temperature. Take a gander at Self-cleaning oven. I'm not familiar with the catalytics of ovens, but cleaning all the residue off of the sides of the oven and the especially the heating elements (Edit: the thing where the gas burns) may restore proper catalytic functioning to your oven (conversion of CO to CO₂) if that is the problem. (I'm just speculating). Definitely get the landlord for this, and if he/she doesn't fix the problem, report it to the proper local authorities.152.16.144.213 (talk) 01:41, 12 February 2009 (UTC)

Say what now? Heating elements? In a gas oven?

(If you're getting CO from an electric oven, something's really wrong...what are you doing in there, making charcoal?) Trovatore (talk) 02:08, 12 February 2009 (UTC)

I am/was definitely using the wrong term. By heating element I mean the part where the gas is burning and generating heat. On stove tops I call them burners, but I have no idea what the proper term is when they're in an oven. I don't mean the bars that you see on the top and bottom of electric ovens which turn orange when hot. And now I know that heating element is specific to electricity --> heat via resistance style heaters. Truthfully, I never noticed what the gas burning/heat generating bit in a gas oven looks like. I use an electric oven which does seem to make charcoal whenever I operate it... 152.16.144.213 (talk) 05:15, 12 February 2009 (UTC)

The detectors I've seen all come with a chart that relates concentration of CO to response time: if the concentration is just over the alarm threshold, it may take the detector as much as an hour to respond. On the other hand, if the CO level is acutely dangerous, the detector will respond within seconds. --Carnildo (talk) 23:39, 11 February 2009 (UTC)

I just wanted to add to Carnildo's info. CO is nasty because it can accumulate physiologically over hours time, so just by hanging around with the oven (assuming the oven is the problem) you have been accumulating CO in your own body. The delayed alarm Carnildo talks about is usually tuned to the physiological uptake. See here for what I mean. When the alarm goes off, it means that if you have stayed in the vicinity, you have potentially been inhaling and accumulating an unsafe level of CO. 152.16.144.213 (talk) 01:41, 12 February 2009 (UTC)

Here's something you could try. Use a lighter and see if you get a difference in the flame at different locations or at different times while/after operating your oven. OR That's what our heating/AC expert used to demonstrate we needed a new furnace in a hurry. (Our CO2 detector upstairs hadn't gone off, but the flame at the furnace was extinguished. Ooops!) 76.97.245.5 (talk) 01:09, 12 February 2009 (UTC)

Um, that seems strange. CO is flammable — I would more expect the lighter to ignite it than be put out by it (not that I'd actually expect either). Unless of course there was so much CO that it displaced the oxygen needed to keep the lighter going. But if there'd been that much I'd expect you to have been seriously injured or killed by it.

CO2 is quite another matter — it's not flammable, but it's much less toxic than CO. If there were enough CO2 to put out your lighter, I wouldn't expect it to kill you, but I'd expect you to notice the tingly sensation in your nostrils. --Trovatore (talk) 01:49, 12 February 2009 (UTC)

Oh wait, maybe I misread you. Are you saying the lighter went out when you held it next to the burner in the furnace? Or are you saying there was no flame in the furnace, but the gas was still being delivered? The latter situation is terribly dangerous, of course, because your house might blow up. But I wouldn't go looking for it with a lighter :-). --Trovatore (talk) 02:03, 12 February 2009 (UTC)

I have a CO detector that has an LED readout which shows parts-per-million of CO in the air. When the readout gets to 50 ppm, it sounds a horn. It's interesting to see the ppm number increase when I run a portable propane heater. The CO detector is 9-volt battery operated and looks like a smoke detector. It didn't cost an awful lot - about $30 I think. GlowWorm —Preceding unsigned comment added by 98.17.34.148 (talk) 01:48, 12 February 2009 (UTC)

You say you live in an apartment. Is it possible that you're picking up CO from someone living above, below or to the side of you. It wouldn't be at all surprising that they would be cooking with a gas stove at around the same time as you are cooking. If so, you should probably talk your neighbours into borrowing your CO detector for a few days to see if they are getting a stronger reading. CO is nasty stuff - so you really need to treat this seriously (that's why you bought the detector - right?). Failing that, you need to talk to a professional. Probably your local fire department could help you...give them a call. SteveBaker (talk) 02:20, 12 February 2009 (UTC)

I would recommend you contact your local fire department about conducting a more thorough CO test to find the actual source of the problem. CO is NOT something you want to mess around with. Also, if you live in an appartment, you should contact your landlord about the problem. If they are not helpful, or dismiss your complaint offhand, I would be VERY concerned; your landlord should fix these problems and if they don't they could find their tenants dropping dead from CO poisoning; which could be very bad for business indeed. So please, contact your landlord and the local fire department. This may be nothing, but its not worth making that assumption and being wrong! --Jayron32.talk.contribs 03:12, 12 February 2009 (UTC)

Just in case our OP needs to be scared into action - what CO does is to latch onto the haemoglobin in your red blood cells at the place where the oxygen normally hooks up. This doesn't kill the cell - but it does prevent it from absorbing oxygen. Hence, whenever you breath in CO, some of your blood pretty much stops working. It stays in your blood stream until the red blood cell eventually dies and is replaced with a nice new one. Since these cells live for about 4 months - continual exposure to even low levels of CO builds up over four months - cutting down your ability to absorb oxygen...it's extremely dangerous. SteveBaker (talk) 04:33, 12 February 2009 (UTC)

As others have mentioned, you need to find out what's causing this ASAP. Others have mentioned batteries but also, unless I'm mistaken (I'm pretty sure it was mentioned in an answer a long long while back) CO detectors have a limited life, like smoke alarms, make sure yours isn't too old Nil Einne (talk) 16:03, 12 February 2009 (UTC)

Metamorphosis

I know that evolution doesn't do anything for a reason. I get that.

That being said: i am totally mystified by metamorphosis. It seems like an incredibly costly method of living! Why would a creature outlast others with such a time-consuming/costly life?

Is there a good reason I'm missing as to why it would benefit butterflies and friends to adapt sucha bizarre life?192.136.22.6 (talk) 23:02, 11 February 2009 (UTC)

I guess we'd have to ask "as opposed to what, remaining a caterpillar ? " StuRat (talk) 23:12, 11 February 2009 (UTC)

Flying is a very convenient way of finding a mate, yet butterfly wings are very fragile so they would be very vulnerable if they had them from the start. Metamorphosis means they can grow and eat while in a sturdy caterpillar form and then fly around and find a mate when the time is right. --Tango (talk) 23:27, 11 February 2009 (UTC)

I have no source for this but metamorphosis might also be a good way to minimize exploitation by parasites and predators by changing living habits and behavior. Predators of caterpillars like wasps would waste energy hunting down maneuverable butterflies. Parasites taking advantage of a caterpillar will have to endure a period of time the caterpillar spent as a pupae before they could exploit the butterfly.

Like Tango was talking about above, metamorphosis also allows an organism to have specialized forms for certain periods of its life rather than have one generalist form. All multicellular organisms must grow and mature before they are capable of breeding successfully. (I can't think of any exceptions...) Metamorphosis allows an organism to start off with one form (eg. larva) which is really good at acquiring nutrition. Breeding isn't an issue at this stage in its life, so why waste energy on reproductive structures and displays? Once it acquires enough energy stores, it can switch into an adult form (imago) which is good at finding a mate, breeding, rearing young, etc. It's evolutionarily "worth it" to have efficient specialized forms even though the organism must acquire a little more energy and spend time in a non-motile pupal form during the transition.

Sometimes metamorphosis isn't the best way to exploit a niche. Reptiles (I really mean Amniotes) bypassed the amphibian metamorphosis which necessitated an aquatic stage in exchange for a dry-land-only reproductive pathway. Reptiles could then exploit terrestrial lifestyles with minimal water contact which amphibians cannot. 152.16.144.213 (talk) 00:44, 12 February 2009 (UTC)

The axolotl agrees with you. --Milkbreath (talk) 01:27, 12 February 2009 (UTC)

The OP says it is a mystery - a mystery how evolution could have brought about insect metamorphosis. A caterpillar with many legs turns into an entirely different creature with 6 legs, a 3-segmented body, and wings. That sort of thing leads me to think that something more remains to be said about evolution - and it's something important. In a post a few days ago I said that it is impossible to see how evolution could have developed certain highly specialized organs that will not perform their function unless already perfected, or nearly perfected. In insect metamorphosis, the entire creature changes from one specialized form to an entirely different specialized form. How could such a change have taken place gradually by evolution? How could it have taken place suddenly? At present, the theory of evolution seems to be incomplete. I wonder what biologist will become famous by completing the theory. – GlowWorm. —Preceding unsigned comment added by 98.17.34.148 (talk) 02:33, 12 February 2009 (UTC)

Actually, evolution is not incomplete in the way you mean it to be. If by incomplete you mean "there are future discoveries which may someday alter or add to the theory of evolution" then that statement is moot, because every single scientific theory, from atomic theory to gravitational theory to anything else also meets that definition. Thus, it is no different in that way from ANY OTHER part of science. If you mean "evolutionary theory does not do a good job of explaining observations or producing good predictions" that is also patently false, it is one of the most productive theories in all of science, and has fantastically good and detailed predictive and explanitory power.

The above post makes some rather starkly poor assumptions. For example, caterpillers have only 6 legs. They may have some operative protuberances called Prolegs which appear either before or after their true legs. However, the same six legs in the caterpillar become those of the butterfly. The actual metamorphosis from caterpillar to butterfly is very well documented, and we pretty much know the entire mechanism inside and out. Secondly, don't be confused by "I find it hard to believe that evolution can explain these things" with "evolution cannot explain these things". Having a personal lack of understanding does not mean that the system itself is flawed. transitional forms of life between non-metamorphising life and highly-metamorphosizing life exist both in the fossil record and in the modern world quite readily. For example, some insects display Hemimetabolism to varying degrees, which is a less advanced form of metamorphosis and which can be shown to make a neat continuous line of evolution between non-metamorphosizing critters and ones like butterflies. Merely because we find it hard to believe that evolution could produce these changes does not mean that it doesn't. And the evidence is plentiful that it does. --Jayron32.talk.contribs 03:06, 12 February 2009 (UTC)

The idea that specialized organs could not have evolved incrementally is called the Irreducible complexity argument. Typically, creationists will pick an organ and claim it could not have evolved incrementally. Then evolutionists will explain how it could have evolved incrementally. Then the creationists pick a new organ, and the cycle continues. --Allen (talk) 03:29, 12 February 2009 (UTC)

Additionally, the idea of irreducable complexity generally rests upon a very small number of organs or processes which may have not yet had complete evolutionary explanations (or more likely, DO have complete evolutionary explanations, which creations conveniently leave out of their analysis). Their arguement is based on the assumption that evolutionary theory is rigid (and thus any small inconsistance disproves the whole theory) or instable (such that a single unexplained fact could bring the whole thing down like a house of cards). In the Kitzmiller v. Dover case, for example, they used the flagellum example ad nauseum. The problem with this was a) even if their single example was as yet poorly explained, it could not stand against the weight of the billions of other well explained parts of evolution and b) it turns out that the flagellum is NOT a good example of irreducable complexity, as there are examples of non-flaggelum organs with similar structures and alternate purposes. The IC arguement almost always falls apart in the face of actual data, and the small handful of cases where it doesn't yet fall apart, its just not enough to take down the entire theory of evolution. The concept of transitional forms are well established, and merely because one can find examples of where those forms have not been found does not mean they never existed... --Jayron32.talk.contribs 03:55, 12 February 2009 (UTC)

Yes - exactly. We are at a position now where 'irreducible complexity' - of which insect metamorphosis is supposedly an example - is busted. There are many MANY cases of impressive evolutionary results that seem impossible at first glance. In many cases, biologists have not yet investigated how they came about. HOWEVER, in every single case that they HAVE studied (the evolution of the eye, the 'motor' on flagellum bacteria are two classic examples), we've found perfectly reasonable proof that these complex organs did indeed evolve from simpler things. But evolution is no longer a hypothetical concept but a totally proven "theory" (in the scientific sense of "law") it's as true as the laws of thermodynamics - but more than that, it's logically impossible for it NOT to be true in any system that includes inheritance, mutation and selection.

Hence, rational debate should logically shift from "How can you justify evolution given this example of seeming irreducible complexity?" to "Given that evolution is known to be true - why is this example of seemingly irreducible complexity wrong?". We now KNOW for absolute sure that insects evolved their metamorphosis trick - we may not yet know why or how - but we know for sure that they did evolve it because we know for sure that evolution is true.

So if our OP is merely offering a straw man to argue against evolution...give it up. The argument (in scientific terms) is long over. If we're really asking how evolution did this rather than whether evolution did it - then this is an interesting (but perhaps as yet unanswered) question.

SteveBaker (talk) 04:23, 12 February 2009 (UTC)

Steve!!! No! I read your responses all the time, and they're so great, clever, and occasionally hilarious. I wasn't even SLIGHTLY posing a straw man argument to knock down evolution. I was genuinely curious as to how such metamorphosis could come about. Science rocks, and the more I learn the more i realize I have to learn. (i'm on a different computer, but i'm the OP if that wasn't clear)24.91.161.116 (talk) 05:48, 12 February 2009 (UTC)

It is fun to guess how these things came about. My favorite poser in regard to the mysteries of evolution is beauty, like reef fish and butterflies and birds of paradise. Their allure is not meant for us, but it might as well have been. (On a side note, if you haven't discovered them already, the Xanth books of Piers Anthony play quite entertainingly with this idea of extreme, inexplicable adaptation. Read them in order; they get weaker as he goes.) You are mystified by metamorphosis, and so am I. All development is a big mystery. The second-by-second interplay of chemistries makes it a puzzle too complex to ever be solved. But it is obvious that development must occur, from egg to adult. Just how it occurs in a particular species is an evolutionary crap shoot. I've always supposed that there are a practically infinite number of ways for living things to be, and we're seeing only a tiny fraction of them in practice. Mutation is a shot in the dark; not every viable mutation happens, and often one that's only barely good enough to start with takes root and flourishes and improves. That's how I explain the hyena to myself. Metamorphosis is nothing more than another way organisms develop. My guess is that the larval stage was originally very short, perhaps happening within the egg case, and proceeded directly to metamorphosis. A mutation extended the larval stage, and this gave some advanatge, like the ability to increase body mass before striking out on the search for a mate. --Milkbreath (talk) 13:44, 12 February 2009 (UTC)

I think the answer to your problem with 'beauty' is (as is commonly stated) that it is "in the eye of the beholder". Creatures didn't evolve beauty. Rather, we evolved to perceive these weird things as beautiful. Looked at that way, the things we find beautiful are generally things that suit or are useful to us. There have been many studies to show that (for example) humans find the most 'average' of faces to be the most beautiful. It is likely that we do this in order to weed out serious imperfections in potential mates by regarding 'average' or 'normal' people as desirable. Perhaps we also do this with plants and animals suitable for food - landscapes suitable for hunting in. Cloud formations that portend good hunting weather...who knows? Doubtless this could be a complicated matter - but it's a much easier explanation than that animals somehow strive to meet human standards of beauty. SteveBaker (talk) 05:54, 13 February 2009 (UTC)

One very new (i.e. likely to be largely untested) idea about metamorphis is that it's possible in some instances it's the result of crossbreeding between two species, see [26] if you're interested. I would emphasise that New Scientist is known for publishing controversial ideas that most experts in the field would say are unlikely or impossible without making this clear. Edit: Actually it's not that new it seems [27] [28] although it looks like it hasn't received much acceptance which makes me even more wary of it Nil Einne (talk) 15:48, 12 February 2009 (UTC)

Some of the criticisms made here of irreducible complexity seem to me to show an intolerance of non-destructive deviation from what is regarded as established truth. I think this results from an over-reaction to the complete denial of evolution that is made by some religious persons.

Also, people sometimes develop a non-rational (emotional) vested interest in a certain religious or nonreligious viewpoint. That leads to a closed mind. Any deviation from the viewpoint arouses a non-rational and somewhat vehement opposition. After all, the viewpoint is believed to be ultimate truth.

Science should be open minded. No scientific fact, principle, or law, should be regarded as ultimate truth. Scientific facts sometimes evolve.

One comment made here was that biological evolution had been proved. Well, Newton proved that gravitation is universal by predicting the paths of planets. However, Einstein showed that Newton didn't get everything quite right. But it may be that Einstein, in turn, didn't get everything quite right either. There is some evidence that there is a fifth fundamental force in the universe instead of the four that Einstein had postulated.

In another example, ohm's Law (R= E/I) doesn't get it quite right either. When a current passes through a resistor, the resistor becomes warmer. That changes its resistance, and the amount of heating depends on the amount of current. Thus, ohm's Law is only an approximation – though the approximation is close enough for most practical uses.

I still maintain that the theory of evolution doesn't get it quite right either. I have read an explanation of how the eye, an IC organ, is supposed to have evolved. I was not convinced. No mention was made of the focusable lens, the expanding/contracting iris opening in response to light intensity, the muscles that move the eye ball in its socket, the development of an optic nerve to the brain, or the ability of the brain to comprehend the nerve impulses received. It seemed that the writer had set out to "prove" a preconceived notion.

I think the advocates of creationism and intelligent design also set out to "prove" preconceived notions. However, I believe their ideas about Irreducible Complexity, in some cases, have validity – they cannot be explained by the theory of evolution in its present form.

The comments here included some internet leads and Wiki references. I am looking into them. Thanks for the references. – GlowWorm —Preceding unsigned comment added by 98.17.32.201 (talk) 20:16, 12 February 2009 (UTC)

I liked the theory that the butterfly was a parasite of the caterpillar, which may be a variation of the theory of the merging of two species, mentioned above. But the evidence is really not there for it. Graeme Bartlett (talk) 20:42, 12 February 2009 (UTC)

Broad-mindedness has to be tempered with skepticism. There also comes a point where assuming that seriously busted theories MIGHT still be true is counter-productive. We are well beyond that point with irreducible complexity. We have NEVER found a case of irreducible complexity that we tried-and-failed to reproduce. The intelligent design nut-jobs keep throwing up new cases - and it does take a while for science to knock them down - but every single one we've actually looked into has been impressively and comprehensively 'busted'. The fact that GloWorm doesn't believe it - is entirely due to failure to read enough about the subject. I have read several books on the evolution of the eye and they are VERY convincing - explaining every teeny-tiny intermediate step - and what evolutionary pressure lead to that change. The eye is FAR from irreducible. You should not allow ignorance to drive belief. Do what I did - hit the books.

You disparage ohms law by calling it an 'approximation'. Nothing could be further from the truth - it's another law that is 100% true. It's true that the resistance of a resistor may change over time for any number of reasons - but at any given instant ohm's law applies perfectly. Ohm's law doesn't say that the resistance of a given object is a constant - and it doesn't predict the voltage, current or resistance at some time in the future. All it says is what happens right now - at a single instant of time...and it's correct. So you can drop that nonsense. (I'm pretty sure I've read the same bullshit anti-science crap you've obviously read because it has the exact same mistakes!)

The idea that Newton was "wrong" and therefore Einstein could still be "wrong" is a gross over-simplification. Newton was essentially correct within the slow-speed realms he was able to explore. Einstein is also susceptible to being wrong (or at least only an approximation) outside of the realms we've explored. However, Einstein predicts an ultimate limit to speed - and we've confirmed his theory all the way up to very VERY close to that speed...and there is no sign of an error. So if someone were to overturn Einstein, he'd have to do it in some realm of speed, gravity, mass, time...that we've NEVER explored. We might (conceivably) find that dark-matter doesn't follow Einstein for example...but we're not going to find a way to breach it in 'normal' ranges such as is occupied by stars, black holes, planets, humans and so forth. So any radical new theory really has to plug one of the teeny-tiny 'gaps' which we have not yet explored...and any change it made would only be important in those same teeny-tiny areas of existence. Just as we can treat Newton's laws as true for cars and yo-yo's - we can treat Einstein as true for particles moving at 99.999% of the speed of light - for stars and galaxies and so forth.

It's the same with evolution. You might find some other planet - upon which Lamarkianism is the means for creatures to change. In that case, evolution might not apply. We might find a planet full of self-reproducing robots and then we'd have to search for the "intelligent designer". But for all of the areas we've ever explored, there is absolutely ZERO experimental evidence to disprove it. So on all of earth that we've explored (and CERTAINLY for humans) - intelligent design isn't even worth the effort to disprove it because we have a theory that fits all of the facts and makes predictions that we can test.

I was just watching the Nova program about the Intelligent Design trial at the Dover School Board. There was a GREAT example of science in action there. Humans appear to be related to the great apes - but we have one less chromosome than they do?!? The prediction one would have to make for that to be the case is that at some time in the past, two ape chromosomes got somehow joined together. Well, all genes of all animals have a specific DNA sequence called a "telomere" on either end of each chromosome and a region called a "centromere" in the middle. If evolution is correct then we should be able to find a chromosome with two centromeres and telomeres in the MIDDLE of the chromosome as well as at both ends. Well, this is a testable hypothesis - and indeed, when we look for that, we do indeed find that one of our longer chromosomes has telomeres in the middle and two centromeres. So a prediction made by evolution theory was shown to be correct. Something that's such a long-shot as that is REALLY tough to attribute to ID. Why on earth would an intelligent designer do such a crazy thing? On the other hand, it's PRECISELY the kind of thing that we expect to happen as a result of evolution. Just how much proof do you need to say that ID is crap?

SteveBaker (talk) 06:25, 13 February 2009 (UTC)

Steve says the theories of Incontrovertible Complexity have been seriously busted. Well, an intelligent person can produce a plausible refutation of almost anything he wants to. But I don't think the busting of IC theories has undergone the ultra-, ultra-rigorous examination and re-examination that the theory of evolution itself has undergone. The never-ending opposition to evolution has made its supporters over-zealous. They will not brook even a suggestion that the theory of evolution, while fundamentally true, is incomplete.

Steve says he has read several books about the evolutionary development of the eye. He also tells me to "hit the books". OK Steve, name the books about development of the eye so I can read them too. (I don't think several books have been written about that one thing. I think he means he read about it IN several books that covered other material as well. All right, I won't take cheap advantage of this. In the quick responses of a post a person does not always express himself precisely.)

As for Ohm's Law, I did not "disparage" it. It is true that it is precise at any given instant. But Ohm's Law is virtually never used in that sense. In any practical use it is an approximation.

I did not say Newton was wrong. I said he didn't have it quite right. And I didn't say Einstein could be wrong because Newton was wrong. I said that perhaps Einstein didn't have it quite right either. That twisting of words is not something that is done inadvertently in a quick reply. It is done deliberately.

I said nothing about Lamarkianism. Don't tar me with that brush.

I do not support creationism or intelligent design, as Steve intimated. I made that quite clear.

All in all, Steve's remarks in his post 06:25, 13 February 2009 (UTC) show the over-zealousness I refered to. It leads to overstepping the bounds of accuracy and to the discourtesy that occurred several times in the post. – GlowWorm.

Reverting to the original question about metamorphosis, I have just (yesterday) finished reading On the Origin of Species by one C. Darwin, and was struck by his take on the matter. In the penultimate Chapter XIII, under the sub-head "Embryology", he writes:

"It has already been casually remarked that certain organs in the individual, which when mature become widely different and serve for different purposes, are in the embryo exactly alike. The embryos, also, of distinct animals within the same class are often strikingly similar: a better proof of this cannot be given, than a circumstance mentioned by Agassiz, namely, that having forgotten to ticket the embryo of some vertibrate animal, he cannot now tell whether it be that of a mammal, bird or reptile. The vermiform larvae of moths, flies, beetles, &c, resemble each other much more closely than do the mature insects; but in the case of larvae, the embryos are active, and have been adapted for special lines of life . . . ."

"The points of structure, in which the embryos of widely different animals of the same class resemble each other, often have no direct relation to their conditions of existence. We cannot, for example, suppose that in the embryos of the vertebrata the peculiar loop-like course of the arteries near the branchial slits are related to similar conditions, - in the young mammal which is nourished in the womb of its mother, in the egg of the bird which is hatched in the nest, in the spawn of a frog under water.

The case, however, is different when an animal during any part of its embryonic career is active and has to provide for itself The period of activity may come on earlier or later in life; but whenever it comes on, the adaptation of the larva to its conditions of life is just as perfect and as beautiful as in the adult animal."

Elsewhere he refers to both some non-insectoid metamorphoses such as those of barnacles (about which he knew more than a little) which involve even more drastic morphological changes than the familiar caterpillar->chrysalis->butterfly, and to some insect growth patterns such as those of aphids in which successive stages display increases in size but little change in form (which, I suggest, we might suppose to be more representative of the earliest examples of life).

In (my) summary: various organisms pass through several stages in their growth; insect larvae are a form of active embryo (i.e. an early stage); adaptive pressures more peculiar to a particular stage of growth can cause modification through natural selection on that particular stage; and, just as evolution can by increments drastically change the morphology of a line of organisms hugely over (sufficient) time, so can successive life stages become greatly dissimilar.

I thoroughly recommend (re-)reading "Origins". Although Darwin's 150-year-old discursive literary style takes a some adjusting to, it is invariably lucid and logical, and while in the earlier chapters he beats about the bush a little, the lattter half of the book is wonderfully concentrated . One is repeatedly struck by his prescient suggestions of possible corroborative discoveries that have, indeed, since been made. 87.81.230.195 (talk) 06:55, 14 February 2009 (UTC)

I find it impossible to read any text that is at all complex. When I was a kid the schoolbooks seemed easy and I could get good grades by just skimming through them. I was never given anything challenging in reading or homework. My parents were poorly educated and took no interest in my schooling - they left it all up to the school. Now I can do only light reading. A few days ago I started Darwin's autobiography (it's available from Gutenberg.org), and it is an easy and interesting read. – GlowWorm. —Preceding unsigned comment added by 98.17.32.201 (talk) 18:55, 14 February 2009 (UTC)

February 12

First Ionization Energy

Hello. If helium has a wider atomic radius than hydrogen and helium electrons are farther away from the nucleus than hydrogen electrons, why does helium have a higher first ionization energy than hydrogen? Thanks in advance. --Mayfare (talk) 02:01, 12 February 2009 (UTC)

You sure about that atomic-radius comparison? But also if you like hand-waving explanations, helium as twice the nuclear charge of hydrogen. DMacks (talk) 02:04, 12 February 2009 (UTC)

Exactly. The two electrons in Helium atom (in its ground state) can not screen the nucleus completely from each-other; thus, each orbital sees, on average, a central (attractive) charge that is higher than 1. The central charge they "see" is more like 1.5, actually. So you need to invest more energy to remove one of the electons. The two electrons are indistinguishable. --Dr Dima (talk) 02:42, 12 February 2009 (UTC)

(edit conflict with Dr Dima) Actually, he's wrong about the atomic radius comparison. There are two main methods of determining atomic radius. The first is to use the average internuclear distance from covalent bonding, since helium forms no known covalent bonds, that method is pretty much out. The second method is to calculate the assumed atomic radius from the effective nuclear charge of the helium relative to its outer electron shell. From those calculations, it is assumed that helium is SMALLER than hydrogen (note that these calculations are approximations, as there are no empirical methods of determining the data for helium, but the numbers come out significantly smaller). Helium does have a larger Van der Waals radius than does hydrogen, but that really has no effect on First ionization energy. Rather, its a measure of how large the atom behaves in the gas-phase, if we treated it like a hard billiard ball. Van der Waals radius has no correlation with how the strongly the electrons are attracted to the nucleus. As Dmacks aluded to, atomic radius is a convenient hand-waving of explaining the trends in ionization energy, the REAL explanation lies in understanding effective nuclear charge. See also Atomic radius and Atomic radii of the elements (data page) for more info. --Jayron32.talk.contribs 02:47, 12 February 2009 (UTC)

Just a curiosity about diatomic helium molecules: [They exist] and have a large separation between the atoms, but they are unstable and really not relevant here ;-) Icek (talk) 14:25, 12 February 2009 (UTC)

Calling those "molecules" stretches the definition of molecule to rediculous bounds. Helium atoms, like ALL atoms and molecules, are susceptible to London forces which result from the polarizability of its electron cloud. The stuff they created was not diatomic helium molecules as much as it was an association of polarized helium atoms. Molecules specifically require "shared" covalent electrons, which this experiment decidedly did NOT produce. --Jayron32.talk.contribs 15:51, 12 February 2009 (UTC)

Mayfare, if you are serious about figuring out why the ground state energy of the Helium atom is as it is, you can work your way through problems to paragraph 69 ("self-consistent field") of the Landau-Lifshits non-relativistic quantum mechanics textbook. It deals exactly with your question. Actually, you would probably like to read the entire chapter X ("Atom"). Note: I have a Russian 4-th edition of the book; chapter and paragraph numbers may differ a bit in English translation, which is from 3-rd edition AFAIR. --Dr Dima (talk) 03:03, 12 February 2009 (UTC)

Real D glassess

So, I got two Real D glasses the other day when I went to see Coraline. The page Real D Cinema explains that they work by separating circularly polarized light. I was playing with them and noticed that if I hold one of them at arms length distance in normal position (front side facing away from me) and look at it through one lense (one at a time) of the other pair of glasses, nothing particularly special happens. But if I hold the first pair bakwards (front side facing away from towards me), when I look through the second pair (through one lense at a time), one of the lenses of the first pair looks dark while the other looks clean. I expected that phenomenon to happen in both situations, but it only happens on the second one. How comes? Dauto (talk) 03:19, 12 February 2009 (UTC)

Well - these are really just polaroid sunglasses with one lens rotated through 90 degrees.

Imagine that light is a wave that's vibrating either horizontally or vertically or both together (that's not really 'right' but it's a good way to imagine what's going on). A polaroid lens behaves like it had tiny vertical 'slots' that would let light that's vibrating vertically pass through the slot - but would block the vibration of light that's vibrating horizontally. (There aren't really 'slots' but it helps the imagination). Hence, with these glasses, one lens allows 'vertically polarized' light to pass and blocks 'horizontally polarized' light - and the other (which has horizontal 'slots') does the opposite.

I'm not sure which eye has which polarisation - but for the sake of my explanation, let's guess and say that the left eye allows vertically polarised light to pass - and the right eye allows horizontally polarised light to pass.

The movie displays alternate frames of the movie with alternate polarisation and moves the viewpoint an inch or so to the left or right on each frame. Thus when a 'right eye' frame of the movie is being projected, the light from the projector is forced to vibrate only in the horizontal direction. Your right eye lens allows the light to pass clearly but the left lens blocks most of the light and dims it down significantly. On the 'left eye' frames, the opposite happens - the projector sends out vertically polarised light and your left eye lens lets it through while the right eye lens blocks it.

One consequence of this (which was VERY noticable during 'Coraline') is that when something moves fast across the screen, it tends to double-image rather badly (this was most noticable for me during the closing credits) - that's because each eye is only seeing 12 frames per second rather than the more usual 24 frames that movies use.

So if you take two pairs of the glasses and look through the left eye or right eye of both together - nothing special happens - the left lens of both glasses allow vertical light to pass - the right lenses both let horizontal light through...things are dimmer but you can see through them both together. But if light passes through the left lens of one pair and the right lens of the other (as happened when you flipped one pair around - then only horizontally polarised light passes the first lens - and then the second lens filters that out because it has a vertically polarised lens - so everything goes very dark.

In regular polaroid sunglasses, both lenses allow only vertically polarised light through because when sunlight is reflected off of water or other flat surfaces, the glasses will dim it down. This is great for cutting out glare on the beach without making things go too dark.

Hence, if you take two pairs of regular polaroid sunglasses and rotate one of them through 90 degrees - you'll get the same effect you see with your 'coraline' 3D glasses.

SteveBaker (talk) 03:42, 12 February 2009 (UTC)

(Incidentally: If you go to see Coraline - firstly be SURE you go to a movie theatre that's showing it in true 3D...only about 50% of them are doing that - and the movie is much better that way! They use 3D exaggeration to make the parallel 'button universe' seem hyper-real and without that effect it's nowhere near so stunning. Secondly, they're going to charge you $2 of the ticket price for the glasses. When you leave the theatre they have a bin where they ask you to "recycle" your glasses. DON'T DO THAT! You bought the glasses - they are yours to keep. The theatres that bought the special 3D display equipment are ramping up for several other 3D movies coming along soon and you can save yourself $2 next time around.) SteveBaker (talk) 03:49, 12 February 2009 (UTC)

SteveBaker, your answer would have been correct 5 years ago, but now it is outdated. see the page Real D Cinema for details. You didn't really answer my question. Dauto (talk) 04:55, 12 February 2009 (UTC)

I'd give it a go, but I am unclear about the placement of the glasses and which lens you are referring to in your description. To clear this up unambiguously, call one pair of glasses Pair 1 and the other Pair 2. When you wear the glasses normally, call the lens that is on your left L and the one on your right R. (It may help to write a little L and R on the frame of the glasses.) 152.16.144.213 (talk) 06:07, 12 February 2009 (UTC)

For the situations below describe if the lens in pair 2 appears clear or dark:

a) 1 and 2 are in the normal position, looking through 1L at 2L:

b) 1 and 2 are in the normal position, looking through 1L at 2R:

c) 1 and 2 are in the normal position, looking through 1R at 2L:

d) 1 and 2 are in the normal position, looking through 1R at 2R:

e) 2 is backwards, 1 is normal, looking through 1L at 2L:

f) 2 is backwards, 1 is normal, looking through 1L at 2R:

g) 2 is backwards, 1 is normal, looking through 1R at 2L:

h) 2 is backwards, 1 is normal, looking through 1R at 2R:

The results would look like this if the lens of the glasses were oppositely circularly polarized and the polarization of 1L=2L and 1R=2R (i.e the left lens of both pairs have the same polarization. The right lens of both pairs have the same polarization, but opposite of the left lens)

a) clear b) dark, c) dark, d) clear, e) dark, f) clear, g) clear, h) dark

Thinking about it some more, I think I made a mistake above; flipping a circular polarizer around backwards will not reverse the polarity. The chirality of the filter will be preserved no matter what orientation it is in so the results should be. a) clear b) dark, c) dark, d) clear, e) clear, f) dark, g) dark, h) clear 152.16.144.213 (talk) 07:35, 12 February 2009 (UTC)

Here is what I see: a)clear, b)clear, c)clear, d)clear, e)clear, f)dark, g)dark, h)clear. Puzzling, ain't it? Dauto (talk) 06:18, 12 February 2009 (UTC)

Hmm, Now I wonder if your glasses are circularly polarized. It would seem the lenses are indeed polarized; from the two cases which you listed as dark all four lenses were involved. If the lenses were circularly polarized, results f and g indicate that 1L and 2R have opposite polarizations, and 1R and 2L have opposite polarizations. Results a and e suggest that 1L and 2L have the same polarization. d and h indicate 1R and 2R have the same polarization. The problem lies in results b and c which suggest that 1L and 2R have the same polarization and 1R and 2L have the same polarization. b and c conflict directly with f and g. So now I must ask are your glasses really circularly polarized? Take the glasses and wear them one at a time standing directly in front of a mirror. Do the lenses in your reflection appear dark or can you see through them? Linearly polarized glasses will be see-through. Reflection in a mirror reverses the circular polarity of light so that light coming out from the glasses which is polarized by them in one direction can't return once being reflected by the mirror, so the glasses will appear dark. 152.16.144.213 (talk) 07:35, 12 February 2009 (UTC)

I'll speculate that they make the circular-polarizing glasses from a quarter-wave plate (probably 15µm-or-so cellophane) oriented at 45° layered in front of a regular linear polarizer. The wave plate converts circular-polarized light to linear polarization — horozontal or vertical, depending on whether it arrived as left- or right-circular polarization.

If I'm right about that, it means that when you look through both sets of glasses forward, the light emerging from pair 2 is linearly polarized, which pair 1's quarter-wave plates convert to circular, and then pair 1's polarizers block half of (so rather than a-d being clear, they should be 50% transmission — or 25% if you count the half that gets blocked by pair #2). When you turn pair #2 backward, its polarizers let through linearly-polarized light, which #2's wave plate converts to circular (left- for one lens, right- for the other), which #1's wave plate converts back to linear (since its slow axis is at 90° to pair #2's, it essentially reverses the effect of #2's wave plate), which is then either completely blocked or completely let through by #1's polarizer, depending on whether its orientation matches #2's (i.e. left-left and right-right get through, left-right and right-left are blocked, as you report above).

(Actually, I'm oversimplifying a little by assuming the wave plates are diagonal and the polarizers are horizontal and vertical — it actually works out the same no matter what the actual orientations are as long as the relation between the wave plate and polarizer are correct in each individual lens.) -- Speaker to Lampposts (talk) 07:46, 12 February 2009 (UTC)

Meh. 3D projection through polarizing filters and the audience with 3D glasses is in no clear way advanced beyond The Stewardesses(1969), which had viewers exiting rubbing their heads with every sign of a n incipient headache. This is technology dating back to the early 1950's. It is better than black and white 3D using red and green filters, but not better than House of Wax (1953 film) or Dial M for Murder (1954 film), except for the march of progress making it harder for a stoned projectionist to reverse the projectors, causing people to look inside out, as was once done at the Biograph Theater in a revival showing of Dial M for Murder . Edison (talk) 06:22, 12 February 2009 (UTC)

It is a new technology. read the page Real D Cinema. Dauto (talk) 06:27, 12 February 2009 (UTC)

(staying with the straying from your original question) Distilling the article, the primary differences are: it uses circular polarization, so that the orientation of one's eyes does not affect the quality; it uses a single, DLP projector (which are very nice); it uses a high framerate (72fps per eye); and, mentioned elsewhere outside Wikipedia, it should be brighter, due to the screens and projectors used. The projector and framerate should reduce jitteryness and differences between the eyes' images, and the brightness helps to compensate for the loss of light associated with the polarized glasses. I've got no idea how it actually pans out, having not seen such a film, but that's the idea of it. -- Consumed Crustacean (talk) 06:38, 12 February 2009 (UTC)

Further diversion from topic : Image quality might not be effected by the orientation of one's eyes, but proper orientation of one's eyes is crucial to the stereoscopic effect. If you tilt your head more than a few degrees your brain won't be able to match up the images anymore and you'll just start see double. APL (talk) 02:07, 13 February 2009 (UTC)

It definately looked much better than the old linearly polarized 3D movies. The movie itself was also good. Dauto (talk) 06:45, 12 February 2009 (UTC)

It's getting more interesting. I decided to hold glass number one backwards too. So to

a) 1 and 2 are in the normal position, looking through 1L at 2L:

b) 1 and 2 are in the normal position, looking through 1L at 2R:

c) 1 and 2 are in the normal position, looking through 1R at 2L:

d) 1 and 2 are in the normal position, looking through 1R at 2R:

e) 2 is backwards, 1 is normal, looking through 1L at 2L:

f) 2 is backwards, 1 is normal, looking through 1L at 2R:

g) 2 is backwards, 1 is normal, looking through 1R at 2L:

h) 2 is backwards, 1 is normal, looking through 1R at 2R:

I am adding now

i) 1 and 2 are backwards, looking through 1L at 2L:

j) 1 and 2 are backwards, looking through 1L at 2R:

k) 1 and 2 are backwards, looking through 1R at 2L:

l) 1 and 2 are backwards, looking through 1R at 2R:

m) 1 is backwards, 2 is normal, looking through 1L at 2L:

n) 1 is backwards, 2 is normal, looking through 1L at 2R:

o) 1 is backwards, 2 is normal, looking through 1R at 2L:

p) 1 is backwards, 2 is normal, looking through 1R at 2R:

and I get a)clear, b)clear, c)clear, d)clear, e)clear, f)dark, g)dark, h)clear, i)clear, j)clear, k)clear, l)clear and here comes the punchline: m), n), o), and p) also look clear but if I turn one of the glasses 90 degrees around the axis of the visual path, they all turn dark!! As if they were linearly polarized. The 90 degrees turning had very small effect over the cases a) through l). I'm really puzzled. Dauto (talk) 07:15, 12 February 2009 (UTC)

Take a look at this and maybe this can help. [29] Definitely do the mirror check for circular polarizers vs linear polarizers the guy describes. You may have to hold them normally and backwards to determine what is going on. 152.16.144.213 (talk) 07:43, 12 February 2009 (UTC)

I want to thank Speaker to Lampposts. His explanation is indeed correct. The easiest way to make a circularly polarised light filter is to combine a linear polariser with a quarter plate of birefringent material (BTW that also explain the slightly purpleish shade that I had observed but neglected to mension). But unless we add the birefringent material on both sides of the lenses (and there is no reason to do that for the movie glasses since it would add cost but no added benefit), the filter works only in the forward direction (I had forgotten that). When held backwards, the filter works as a regular linear polariser. So, in configurations a) through d) I'm looking at linearly polarised light through circularly polarised blockers and should indeed always get a clear result. In configurations e) through h) I'm looking at circularly polarised light through circularly polarised blockers and should indeed get the clear-dark-dark-clear pattern observed. In configurations i) through l) I'm looking at circularly polarised light with linearly polarised blockers and see all of them as clear. Finally, in the configurations m) through p) I'm looking at linearly polarised light through linearly polarised blockers and should get either clear or dark depending on the orientation around the optical axis as indeed observed. That explains it all. Thank you. Dauto (talk) 17:25, 12 February 2009 (UTC)

milky way in the sky

A little help in mapping the skies. Can I see the milky way clearly with the naked eye? If it is, can you provide a useful map to help me find it. If it could help, I always see Orion or the Dog Star overhead or slightly near it on clear nights (I'm in the Philippines). If not then what cheap instruments should I use to see it clearly.--Lenticel ^(talk) 05:50, 12 February 2009 (UTC)

Yes you can see it, but you won't see it near a large city due to light polution. You don't need a map. it crosses the sky from side to side. Check out Milky Way. Dauto (talk) 06:07, 12 February 2009 (UTC)

It can be hard to see things that you are inside of. Edison (talk) 06:10, 12 February 2009 (UTC)

The "Milky Way" in this context refers to the disc of our galaxy, it appears as a wispy, almost cloud-like band all the way around the sky (it's more dramatic when you are facing towards the centre of the galaxy, which I think is somewhere is the southern (celestial) hemisphere. --Tango (talk) 13:58, 12 February 2009 (UTC)

You can see it by eye fairly easily, assuming there isn't too much light pollution, nor a full moon. Magnification will not help, it will only make things more difficult. A camera that handles low-light well might let you "see" it better, but if sky conditions are poor enough that you can't see it naked-eye, any photos you take may just be washed out. The "milky way" you see in the sky corresponds to the plane of the galaxy (ie. looking directly along the galactic disc rather than above or below it), so it's the region of the greatest density of stars. It appears as a bright region with many stars, and with a background haze to it from the stars you can't make out directly.

As for maps: star chart / planetarium software such as Stellarium, Cartes du Ciel and Worldwide Telescope do the best job. They let you choose your position on Earth and a time, and they show you a nice picture of the sky along with information on various features up there. Those three are free; Stellarium is the easiest to use, Cartes du Ciel is the most useful; Worldwide Telescope is probably the least easy at this point, but it does let you see actual images of the sky and various objects, which the other two don't (Google Earth has similar functionality, but I find it... lacking). -- Consumed Crustacean (talk) 06:18, 12 February 2009 (UTC)

thanks the article says it crosses Orion, Canis Major and Taurus so I think it'll be easy to spot. Its full moon tonight so I guess I have to wait a little.--Lenticel ^(talk) 11:00, 12 February 2009 (UTC)

Today's APOD has a picture of the Milky Way, here. It's the big purple thing on the right. --Sean 17:18, 12 February 2009 (UTC)

If you live in a region where low clouds glow orange, red, or yellow, or there are streetlights bright enough to cast a shadow from your observing location, then your limiting magnitude is probably too low to find the Milky Way. Try to find your limiting magnitude by finding nearby stars. For example, can you find the star Arneb? A limiting magnitude higher than +5.5 (with no glare is usually good enough to find the Milky Way. If the Milky Way if up on a dark night, with no objects obsucuring it, then you can't miss it. Binoculars or a telescope might aid you in finding the Milky Way, but remember that they show you a much smaller area of sky, rather than the entirety of the Milky Way. You might be able to find a light pollution map online. The Milky Way is most easily visible far from city locations. ~AH1^(TCU) 22:50, 13 February 2009 (UTC)

A map of light pollution is available at [30]. If you're in a white, red, orange, or yellow zone, the Milky Way is going to be hard or impossible to see; if you're in a grey or black zone, it'll be hard not to see. --Carnildo (talk) 00:04, 14 February 2009 (UTC)

Actually, I don't think that's a very good description. I find that the Milky Way is pretty much impossible to see from white or red areas. Orange areas are a bit iffy, if there are any lights in the vicinity, it will be difficult to see the Milky Way, but if there are no lights, then the Milky Way should be clearly visible. One time I saw the Milky Way from an orange area with no streetlights, and the sight was simply unforgettable. Yellow or green areas will produce a visible Milky Way, but likely not all visible details will be seen. Anything darker than that will produce a truly sensational sight. I live in a red area, and the limiting magnitude (for my eyes, after dark adaptation away from as many streetlights as possible) is about +4.5, and I have relatively poor eyesight. A better description of the colours is available at http://www.cleardarksky.com , but it only works for locations in North America. Hope this helps. ~AH1^(TCU) 02:15, 14 February 2009 (UTC)

What is the largest academic journal in the world

By publication volume (published papers per year), what is the largest academic journal (and how many papers do they publish)? —Preceding unsigned comment added by 24.5.116.52 (talk) 06:02, 12 February 2009 (UTC)

I don't know the answer to your question, but Journal of Geophysical Research often runs more than 30,000 pages per year. Dragons flight (talk) 06:14, 12 February 2009 (UTC)

On the other hand, IEEE would probably have more than that if they published as a single journal, but they break up in to more than 140 different sub-journals, (well, "Journals," "Transactions," "Letters," and "Magazines"). Nimur (talk) 09:12, 12 February 2009 (UTC)

I would also note there are peer reviewed academic journals outside the sciences. Since this question is on the science desk, it's more likely responders will be primarily familiar with scientific journals Nil Einne (talk) 11:18, 12 February 2009 (UTC)

Though it's likely that a science journal would probably be the winner of this question, as science articles are usually (but of course not always) quite small (unlike academic journals in the humanities). In fact I wouldn't be surprised if the winner wasn't something like Nature or Science that comes out every week and has tons of tiny articles crammed into it. --98.217.14.211 (talk) 12:52, 12 February 2009 (UTC)

Authoritative anatomy terminology

Some time ago I recall reading about a set of definitive anatomical terminology, giving precise and uniform definitions to various anatomical terms. In some sense, the official guide to anatomical terms. I can't seem to find the title now, however; does anyone know what it is? Many thanks, --TeaDrinker (talk) 07:14, 12 February 2009 (UTC)

Gray's Anatomy. --TammyMoet (talk) 08:52, 12 February 2009 (UTC)

Ah thanks! I appreciate the help. Gray's was not the one I was thinking of, but I did find the one I had in mind (Terminologia Anatomica). Thanks again, --TeaDrinker (talk) 10:16, 12 February 2009 (UTC)

Another idea would be to look for a suitable anatomy ontology which would have probably crisp definitions, too. --Ayacop (talk) 18:50, 12 February 2009 (UTC)

Darwin mechanism of evolution?

People always say that Darwin didn't propose (or even think about) a mechanism by which he thought evolution could occur. I find this hard to believe. Are there any records that hint at HOW he thought evolution might occur?

Thanks

Aaadddaaammm (talk) 13:52, 12 February 2009 (UTC)

Darwin wrote a great deal on the mechanisms of evolution. I think you mean that he did not know the underlying mechanism of heredity, which of course is required for evolution or anything like it. Our article pangenesis has some information on his (totally wrong) theory of heredity. Algebraist 14:04, 12 February 2009 (UTC)

Yes and no. Darwin didn't know about DNA molecules - so he certainly didn't have the whole picture.

He did know that offspring of parents generally inherit the characteristics of their parents - yet sometimes have one or two traits that are different from either of them. He also knew that these inherited characteristics would affect the ability of an animal or plant to survive and reproduce. Those are the only two things you need to know to formulate evolution as a hypothesis. If a particular inherited characteristic increases the probability of that organism surviving and reproducing - then there is more chance of that characteristic being in the next generation. If a heritable characteristic makes the creature less likely to survive and reproduce then that characteristic will be much less likely to be present in the next generation. Hence there is a tendency over many generations for creatures to change to be better and better able to survive and reproduce. That's evolution in a nutshell and there is nothing at all complicated about it. It's absolutely inevitable. Darwin knew that much. However, that's just a hypothesis. To become an accepted 'theory' or 'law' - the hypothesis has to be proved by experiment or observation - and (preferably) explained in detail. We can demonstrate it in action with fairly simple experiments using bacteria cultures - we can also observe it in action with (for example) Warfarin resistance in rats, antibiotic-resistance in hospitals and lactose tolerance in humans. We can explain the inheritance using what we know of DNA and RNA biochemistry. But none of those things were known to Darwin.

The fact that Darwin cannot be said to have proven his theory is rather irrelevant. It's quite common for one scientist to come up with a really good hypothesis and for others to prove it and turn it into a proper scientific law. Einstein (for example) never did a practical experiment in his life - but he turned out some very impressive hypotheses that others subsequently proved.

As for records - Darwin's books survive and you can even read them online at Project Gutenberg - here: [31] - he wrote an autobiography [32] and of course his main work on evolution The origin of species and various others [33] [34].

But (and this is important) our modern theory of evolution stands alone - it's not dependent on what Darwin did or didn't know. Even if his hypothesis was a complete guess at the time - it's been proven to be true hundreds and hundreds of times since.

SteveBaker (talk) 14:26, 12 February 2009 (UTC)

To nit-pick... the difference between a hypothesis and a theory is not experimental testing; a theory is just a testable hypothesis (but you don't have to test it and if you do test it, it doesn't have to work out... there are plenty of wrong theories which are still "theories"). Law doesn't really have a lot of real philosophy-of-science meaning, other than being some sort of simple, iron-clad relationship. (It is not higher on the truth or explanatory ladder than "theory" in any meaningful sense. Newton's Laws are still laws even though they are not as accurate an explanation of gravity, say, General Relativity.) And as to evolution... even *WE* don't know "the whole picture"—hence it's still a topic people do research and publish on to great effect.

As for Darwin's musings on heredity... it's of note that today we consider heredity to be the real underpinning of natural selection but that is not the conceptual framework that Darwin had at the time. Heredity was indeed important to him but understanding evolution as heredity-plus-time is more how Darwin's successors (including his infamous cousin, Francis Galton) thought than the somewhat more Romantic tools that Darwin used for thinking about species. Darwin did muse about heredity quite a bit but it wasn't especially systematic. (And it's of note that even Mendel, who we most of the credit for genetics to, wasn't really trying to come up with a generalized theory of genetics himself. It turns out his work serves as a great basis for doing such a thing, but that was not his research project or what he argued he had done.) --98.217.14.211 (talk) 23:17, 12 February 2009 (UTC)

To nit-pick Steve Baker, but there is no "truth" in science. Darwin's theory (hypothesis isn't quite right) was a guess, it's been tested, and the Theory of Evolution passes the tests, but science doesn't work in "truths." I would say that scientific evidence broadly supports the Theory of Evolution. OrangeMarlin ^{Talk• Contributions} 23:20, 12 February 2009 (UTC)

That's an extremely perverse usage of the word 'truth', which would disallow using it with regard to any statements about the world at all. Exactly the same could be said about the (tested, not yet refuted, supported by evidence) theory that my drinking a glass of water will not cause my head to be destroyed in an annihilation explosion. Algebraist 23:26, 12 February 2009 (UTC)

All science has is theories with varying degrees of evidence to support them. At what level of evidence do you apply the designation "true"? In imprecise everyday language, we talk about things being true and false, but they aren't well defined scientific terms. Things like "proof" and "truth" and other absolute things are the realms of mathematics (modulo Gödel), they don't exist in science. --Tango (talk) 00:44, 13 February 2009 (UTC)

Yes, exactly. As I said, this usage of "truth" leads to us not being able to assert any substantive statement as true, and thus we lose a perfectly good and useful word. I'd rather keep the word "true" and accept that the statements I assert to be true are not necessarily immune to all possible doubt. Algebraist 00:51, 13 February 2009 (UTC)

If true means "stands up to rigorous testing" then evolution is "true". If true means "unchanging and invioble statement about how things are, always have been, and always must be" then nothing in science can said to be true. Scientific truths are said to be the former, and religious truths fit under the later category. Its a shame that we use the same word to describe these two different concepts, because they really apply to very different aspects of the human experience and it would be nice to have different little words to describe these two different concepts. Alas, English is an imprecise language, and sadly the same word is used to describe both states, much as the word "theory" and other which have different contextual meanings which get bent in ways to make them fit whatever your political agenda is. <sigh>. --Jayron32.talk.contribs 02:14, 13 February 2009 (UTC)

If, on the other hand, we take 'true' to have its normal English meaning, so that 'statement P is true' is just another way of saying 'P', then scientific truths are true while religious truths are not true. Algebraist 12:50, 13 February 2009 (UTC)

<unindent>

I think we should allow 'truth' to be applied as an absolute thing in the mathematical sense of some theorem being derivable from some set of axioms. To pick an example: If we accept Euclid's axioms about geometry then "the interior angles of a triangle sum to 180 degrees" is 'true' relative to those axioms - although it's certainly 'false' if you are doing geometry on the surface of a sphere (for example) because the parallel line axiom is not true on the surface of a sphere.

Evolution is 'true' in that sense if you accept the axioms that:

• there is inheritance of traits from parent(s) to offspring
• there are sometimes mutations that result in new traits appearing
• having traits that suit the prevailing environment will result in an improved probabilty of an organism reproducing and passing those traits onto its offspring.

Accept those three axioms and you must accept that evolution is inevitable and 'true' in the fundamental mathematical sense.

To disprove Evolution in a more general sense of the word "true", you'd need to show that one or more of its axioms does not correspond to the world we live in and to the systems we apply it to. If you could show (for example) that genetics was false and that (say) Lamarckism were true instead - then evolution could be shown to be 'false' in the real world sense. However, you'd still say that it's true in the mathematical sense. If real animals reproduced in a Lamarkian manner - then evolution would be false as applied to the real world - but could still be true in the sense of generating evolutionary computer algorithms. We might well find another planet where living things don't have DNA - and it's possible that evolution would not apply there. After all - evolution doesn't apply to car manufacturing - it is false to claim that evolution explains why my car has headlights.

However, the three main axioms on which evolution sits have been shown to pertain to the real world to a highly convincing degree. So we may safely say that evolution is definitely 'true' in the mathematical sense...and as true as the theories of genetics and 'survival of the fittest' - in the more general sense of 'truth'.

The same can be said of most scientific theories and laws...if you disprove the axioms then all bets are off.

SteveBaker (talk) 05:39, 13 February 2009 (UTC)

The "Theory of Evolution" says more than just that evolution happens, it says evolution is responsible for the variety of life we see around us. Anyone denying evolution happens is just an idiot and is best ignored (you can't reason with unreasonable people). Denying that evolution caused what we see around us is rather more legitimate - the evidence is certainly extremely strongly in favour of evolution as the cause, but there are still gaps in the theory to be filled and you can come up with a vaguely reasonable argument that there must be something more too it. That evolution happens can be seen as a "mathematical truth" (given the assumptions you list, which it is completely unreasonable to deny), that evolution is responsible for the variety of life around us (for the origin of species, if you will) is a "scientific truth". --Tango (talk) 13:42, 13 February 2009 (UTC)

I don't think there is a reasonable argument that "there must be something more to it". The word must implies that we have some proof. I would be happier with some argument that says there might be more to it. Indeed - if you look at dogs, they didn't arrive at the DNA they have now by simple natural selection. Toy Poodles didn't "evolve" from wolves - rather humans intervened and produced the poodle by selective breeding. Similarly, 'starlink' corn (see Transgenic maize) did not evolve - humans implanted genes from a bacterium into the DNA of the corn plant om order to make it disease resistant. GloFish are another example.

If the people who object to evolution were indeed pointing at those weird cases, then we'd be forced to agree that not all organisms "evolved" to the state they are at now because some were intentionally designed by humans. But that's NOT what these people are arguing. They are saying specifically that humans did not arrive by evolution because that directly contradicts their religion. That's a serious problem because the genetics of humans is rather well understood and it's extremely clear that we DID evolve right along with all of the other great apes from a common ancestor - and natural selection is the sole driving force behind those changes.

If the anti-evolution people were protesting that we should not be teaching that StarLink corn 'evolved' from regular corn - then the scientific community would be happier to accept that teeny-tiny caveat...but they aren't. They are trying to use this as a 'wedge issue' to try to overturn science and any other source of information that contradicts their world-view. If we don't want the Christian equivalent of the Taliban running the place - we owe it to the world to keep this debate 'on the rails'. SteveBaker (talk) 16:35, 13 February 2009 (UTC)

Bodyhair

Which bodyparts don't have hair growing on them? —Preceding unsigned comment added by 83.80.64.227 (talk) 14:23, 12 February 2009 (UTC)

Eyes? Nails? I assume that you mean external body parts. Anything in your mouth (assuming that counts as external). A Quest For Knowledge (talk) 14:32, 12 February 2009 (UTC)

Thin particular piece of homework seem to frequently stump students. Here's a novel idea: Since you couldn't or wouldn't find it in your biology textbook, go to hair. (If you click on the blue words they will get you to the respective pages. You can also type your word into the search window in the side-bar.) There you will find many more links. One of them will be for Hair follicle. Learning how to find information without having to ask someone is an important part of what they teach you at school.76.97.245.5 (talk) 14:51, 12 February 2009 (UTC)

All of them, if you have alopecia universalis. --Sean 16:15, 12 February 2009 (UTC)

Cognation Memory

Till what age does a human memory grow123.252.230.201 (talk) 17:14, 12 February 2009 (UTC)

Death? I'm not sure that memory grows much after death... --Jayron32.talk.contribs 17:58, 12 February 2009 (UTC)

See Memory and aging. Unlike in some animals, humans' ability to form new memories merely declines with age rather than stops. 76.97.245.5 (talk) 18:00, 12 February 2009 (UTC)

Do you have an example of an animal that can't form new memories after a certain age? --Tango (talk) 19:05, 12 February 2009 (UTC)

Sorry Tango I'd love to have dragged a nice scientific article out of my google sleeve. Unfortunately nothing concise and usable came up in a quick search. So all I can give you is some murky synthesis of things I read. For quite a few animals there are things that they can't learn past a certain age. Cats e.g. can't learn how to apply a killing bite if they don't learn that at a young age. They'll catch prey, play with it, but remain unable to kill it by biting its neck. I've also read that some animals are unable to learn proper sorting of other animals into threat, food, social members and others later in life. (OR: We had a bottle-raised tom cat who was mortally afraid of mice!) And here's one example [[35]]. [[36]]. That certain birds recognize the first animal they see when they hatch as mother is well documented. I should probably have qualified my comment a bit more. Certain memories definitely get "hardwired" (imprinted) and can't be replaced with new ones. I seem to remember some reports on an overall learning cap, but can't recall any specifics to google details. One would be tempted to think that the higher developed the animal the more flexible its memory should be, but that would be wrong, considering examples like bees or parrots. 76.97.245.5 (talk) 01:54, 13 February 2009 (UTC)

I'm not sure that our memory capacity does 'grow'. I think we probably forget things at least as fast as we remember them. Old memories get less and less detailed as time goes on - and in the end, the total number of 'bits' stored there remains a constant. SteveBaker (talk) 05:14, 13 February 2009 (UTC)

So you're saying I can justifiably forget my aniversary because I had to learn my son's birthday? Cool. Someguy1221 (talk) 06:47, 13 February 2009 (UTC)

Well, since this is the Science Reference Desk, you should try the experiment and report back the results. Lotsa luck with that : ) 87.81.230.195 (talk) 07:10, 14 February 2009 (UTC)

The whole "storage" analogy unfortunately doesn't pan out. Scientist are still busy trying to figure out what's going on. What we call "memory" is actually a complex string of information. If you store pictures of a green and a yellow apple in your computer you'd have to store information on each image. Your brain may just store apple, yellow and ditto, green. But it might just as likely do something like - round fruit, color of my favorite blanket, like taste and round fruit, color of patch of lawn in the garden in sunshine, hate taste. Of course you would memorize more things that are the color of your favorite blanket so you'd only need to store that information once. And you'll always remember that blanket because so many things link there. - Until you find a color name "golden" and like that. Little by little you can forget about that blanket because all the blanket color things are "golden". Well, that particular blanket. You'll probably still remember that those square fluffy fabric things are blankets. So if your momn should call you an tell you she found "your favorite yellow blanket", your memory will happily provide a picture of a (canary) yellow full-size blanket and convince you that's it. When you then go and see the real thing you'll say "Strange I remembered it to be a different color and bigger." :) Memory is way more complicated than that (and I don't want to claim I know even the tip of that iceberg). So it's not that easy to say what has grown or not grown. If we go with computer analogies I'd liken it more to defining, linking, redefining, deleting table spaces, and writing queries in a multi-relational database. (... and the DBA won't talk to anyone:-) What I find amazing is that so many things seem to be stored in a similar fashion in different people. I remember reading that scientist were surprised to find in a study that people seem to have a "vegetable" section in their memory. A certain area of the brain lit up when test subjects were shown pictures of vegetables and asked to think about vegetables. Someone who had suffered brain damage in that same location had a good memory except when it came to vegetables. Odd, no? Sorry for (again) not linking references it's way too late and I still got work I'm trying to avoid doing. I came across these pages that you might find interesting. [37], [38] and SciAm has a whole magazine dealing with related topics: {http://www.sciam.com/sciammind/] -76.97.245.5 (talk) 08:15, 13 February 2009 (UTC)

Same-sex gametes combining to form a zygote?

The Encarta Dictionary entry on gamete says:

• male or female cell: a specialized male or female cell with half the normal number of chromosomes that unites with another cell of the opposite sex in the process of sexual reproduction. Ova and spermatozoa are gametes that unite to produce a cell (zygote) that may develop into an embryo.

With in vitro fertilization, couldn't a zygote (and viable embryo) be produced from two ova or two spermatozoa? If no, why not, and might a procedure be found to make this possible? I realize this might be common knowledge I've simply missed, but the pages on zygote and sexual reproduction aren't explicit on this point. -- Deborahjay (talk) 17:43, 12 February 2009 (UTC)

You can't combine two sperm to make a viable embryo, since sperm don't contain much more than DNA, the ovum has all the rest of the stuff needed to produce an embryo (just compare their sizes to get a good impression of how much would be missing). You might be able to fertilise an ovum with the nucleus taken from another ovum, I'm not sure. (Obviously, if you did, you would only ever get female offspring.) --Tango (talk) 17:58, 12 February 2009 (UTC)

Um. I seem to recall something with frogs for the ovum plus nucleus of another ovum arrangement; don't know about any higher life-forms. As for the males: what about emptying the genetic material from an ovum and filling it with the nucleii of two spermatozotes? -- Deborahjay (talk) 18:11, 12 February 2009 (UTC)

I'd think that's theoretically possible. But the hard part is removing only the maternal DNA. The maternal mRNA (which is derived from maternal DNA) is also important for embryonic development. I don't know how the DNA could be replaced while leaving the mRNA and other stuff in the nucleus intact.128.163.80.152 (talk) 18:19, 12 February 2009 (UTC)

Not only is this theoretically possible, it has been done. Removing the egg's nuclear material is a well practiced procedure, so that's actually the easy part. The problem in mammals is epigenetic imprinting, which renders the male and female contributions to the genome non-equivalent, even after discounting the sex chromosomes. Thus, a mammalian embryo derived solely from male or female nuclear material will be effectively homozygous lethal for a number of genes. Reading from Developmental Biology: 8th Edition (Gilbert) the earliest evidence for this came from hydatidiform mole, which can occur from the fertilization of an empty egg by a sperm. Evidence also appeared from attempts to induce parthenogenesis in mice (by suppressing the seperation of nuclear material during the second meiotic division). The embryo develops the full range of tissues and early organs, but development ceases by day 10 or 11. Attempts to fertilize eggs with two egg nuclei or an empty egg with two sperm nuclei all failed (hundreds of times), although the precise phenotypes seen in the failed embryos differed between the di-maternal and di-paternal embryos. However, female mice that are mutated to exibit DNA methylation patterns in their eggs similar to males can form a viable di-maternal zygote when artifically mated with a normal female. It should be noted that the procedures that have been developed thus far are confined to genetically manipulated mice, so men don't have to worry about becoming unnecessary quite yet. References:

• Jacobs, P. A., C. M. Wilson, J. A. Sprenkle, N. B. Rosenshein and B. R. Migeon. 1980. Mechanism of origin of complete hydatidiform moles. Nature 286: 714–717.
• Kaufman, M. H., S. C. Barton and M. A. H. Surani. 1977. Normal postimplantation development of mouse parthenogenetic embryos to the forelimb bud stage. Nature 265: 53–55.
• Surani, M. A. H. and S. C. Barton. 1983. Development of gynogenetic eggs in the mouse: Implications for parthenogenetic embryos. Science 222: 1034–1037.
• Surani, M. A. H., S. C. Barton and M. L. Norris. 1986. Nuclear transplantation in the mouse: Heritable differences between parental genomes after activation of the embryonic genome. Cell 45: 127–137.
• McGrath, J. and D. Solter. 1984. Completion of mouse embryogenesis requires both the maternal and paternal genome. Cell 37: 179–183.
• Kono, T. and 8 others. 1994. Birth of parthenogenic mice that can develop to adulthood. Nature 428: 860–864.
• Vogel, G. 2004. Japanese scientists create fatherless mouse. Science 304: 501–503.

I believe I read this somewhere on Wikipedia once too, but I can't remember what page, nor can I find it now. Someguy1221 (talk) 18:47, 12 February 2009 (UTC)

By an odd coincidence, this was mentioned today on the Straight Dope homepage. Here is the column: "Can Two Women Make a Baby". APL (talk) 19:09, 12 February 2009 (UTC)

universe expanding

is it atruth that the fact of universe expanding been known before the modern world, if so please be clear about it , need solid evidence ,, thanks..? —Preceding unsigned comment added by 86.108.60.36 (talk) 18:07, 12 February 2009 (UTC)

Considering that before the "modern world", people mostly thought that the stars were little holes punched in a black piece of paper hung a few hundred feet over their head (or something not unlike that) then it seems unlikely that anything resembling a modern scientific explanation of the universe that involved expansion existed before, say, Edwin Hubble. It may be entirely possible that we can find some ancient mythology which says something that might be like an expanding universe, but this has little correlation to actual scientific thought, and instead has a lot more to do with "making up stuff". Making up stuff was a long-held method of explaining the universe, and unfortunately it has turned out to be somewhat less accurate than the scientific methods of doing so. --Jayron32.talk.contribs 18:13, 12 February 2009 (UTC)

Somebody might have said it for all I know. However there is a great deal of difference between somebody saying something and knowing it. The only possible evidence I can think for it before the last century would be that the night sky is black, see Olbers' paradox. Someone could have formed a rational hypothesis based on that. Look for quoted evidence before agreeing someone knows something. Dmcq (talk) 18:18, 12 February 2009 (UTC)

From the article that Dmcq suggested: Edgar Allan Poe was the first to solve Olbers' paradox when he observed in his essay Eureka: A Prose Poem (1848):

"Were the succession of stars endless, then the background of the sky would present us a uniform luminosity, like that displayed by the Galaxy –since there could be absolutely no point, in all that background, at which would not exist a star. The only mode, therefore, in which, under such a state of affairs, we could comprehend the voids which our telescopes find in innumerable directions, would be by supposing the distance of the invisible background so immense that no ray from it has yet been able to reach us at all."[39]

I don't know if Poe was the first, but I'm surprised that Edgar Allen Poe of all people wrote on the topic. I'll have to look at Eureka: A Prose Poem. He was writing in the industrial revolution period though, so he seems pretty modern.65.190.207.110 (talk) 20:34, 12 February 2009 (UTC)

I must comment on the above parenthetical statement "(or something not unlike that)". Whenever you feel the urge to write something like that please repeat to yourself: "The not unbrown dog ran not unquickly around the not ungreen field." —Preceding unsigned comment added by 82.120.236.246 (talk) 20:46, 12 February 2009 (UTC)

I disagree. Litotes is an ancient and honored rhetorical figure, not without appropriate uses. Arbitrarily banning it is not harmless. --Trovatore (talk) 21:44, 12 February 2009 (UTC)

I disagree too. "Not unlike" is not equivalent to "like" - it would be if there was a perfect dichotomy between "like" and "unlike", but there isn't. There is a spectrum of likeness, and "not unlike" and "like" cover different (overlapping) parts of that spectrum. --Tango (talk) 22:23, 12 February 2009 (UTC)

It's more subtle than that. The semantics of natural language are not first-order logic, not even with fuzziness added. --Trovatore (talk) 22:33, 12 February 2009 (UTC)

Well, yes, I simplified it to make it possible to explain without writing several essays on the subject. I don't think I over-simplified it - what I said is sufficiently accurate that it does support my conclusion. --Tango (talk) 22:57, 12 February 2009 (UTC)

will .. doing some search i found this strang info ...http://www.metacafe.com/watch/933749//...follow this link ... its confusing ... what did you think...?

I don't see what's confusing. The Qur'an contains an unjustified assertion that happens to be correct. It contains lots of assertions, random chance means some of them are likely to be correct. There is a big difference between making a hypothesis with no justification and making a hypothesis based on significant empirical evidence. The former is not at all interesting. --Tango (talk) 23:13, 12 February 2009 (UTC)

There is a huge gulf between suspecting that something is true and knowing that something is true. We've only known that the universe is expanding since we discovered that galaxies are not stars and that there is 'red-shift' that increases with distance from us. That knowledge can't possibly have existed before we had spectrometers attached to telescopes and before we'd discovered things like quasars and other "cosmic rulers" for estimating distances. So we've only known that the universe is expanding for maybe 70 years. Prior to that, Einstein had math that suggested that the universe ought to be expanding - but he made the fatal mistake of disbelieving the math and sticking an arbitary term into his equations to cancel it out. So even as recently as the 1920's, we definitely didn't know that the universe was expanding. Now - it is perfectly possible that humans 'suspected' or 'guessed' or 'hypothesised' that the universe might be expanding - possibly hundreds or even thousands of years ago - but they most definitely didn't know that it did. There is no way with their technology for them to have measured the red-shift. SteveBaker (talk) 05:04, 13 February 2009 (UTC)

I just had a google on the phrase and this is what itcame up with at the top [40] It looks like it is a recent translation to be in line with science but previous translators haven't said anything like it. So, as the MythBusters say, Busted. Dmcq (talk) 13:16, 13 February 2009 (UTC)

will my clothes rot / otherwise become damaged if I leave them unwashed for a few weeks?

If I leave normal B.O. etc dirty laundry unwashed for a few weeks will it rot / become damaged in any way etc - or will the first wash (with a quality detergent) return it to the same state it would have been in if I'd have washed it just 2 days later. I'm talking about just normal laundry from being worn/in contact with body, no special stains. Thanks. —Preceding unsigned comment added by 82.120.236.246 (talk) 20:51, 12 February 2009 (UTC)

Never tried that :) but I would not be surprised if some kind of mold (fungus) would proliferate and damage the fabric irreversibly. So don't do it. On a side note, people believed for a relatively long time in the Spontaneous Generation of mice in piles of dirty laundry. That belief was eventually proved incorrect ;) --Dr Dima (talk) 21:36, 12 February 2009 (UTC)

As long as it isn't damp, I expect it would be fine. It might start to smell a bit because of the growth of bacteria, but it should be fine after being washed (maybe on a slightly higher temperature that usual). I've certainly left clothes unwashed for pretty long periods of time with no problems (there's always something at the bottom of the laundry basket that won't fit in the machine, and since laundry baskets are first-in-last-out, it tends to be the same thing! There's also the clothes you wear the day before going away for a long time - there's not much you can do about them. They've always been fine when I get home.). --Tango (talk) 21:44, 12 February 2009 (UTC)

My (scientifically nonrigorous) experience is that it can be more difficult to remove the odor after it has "set in"; several washings may be required. This is particularly true of athletic clothing, in the sense that such a shirt may smell OK right out of the dryer, but as soon as you start to sweat in it, you'll be able to tell it's not a new shirt.

But "rotting" -- no, I don't think so. Not unless you don't let the clothing dry thoroughly. --Trovatore (talk) 21:50, 12 February 2009 (UTC)

If you store them in a tight wad or plastic bag and have high air humidity they can get a bit moldy. Towels and bathrobes tossed on top can have the same effect. Spots, sweat and deodorant stains are a lot harder to get out the longer they sit there. They can be undetectable to begin with and then turn yellow or brown with time. Damage to your clothes then happens as collateral damage in the course of the chemical warfare undertaken to combat those set in stains. Food stains can attract bugs that then will find the cotton of your T-shirt quite palatable as well. Elastic waistbands and the like can become brittle (not sure due to what process, maybe deodorant residue or some acids in sweat break the cross-links). Colored clothes that are left out in a place where they are exposed to sunshine can develop faded areas. (E.g. T-shirt sleeve sticking our of the laundry basket.) Beach- and swimwear should be rinsed and dried promptly because suntan lotion will create permanent stains and salt or chlorine residue will damage clothes. Cheap jeans buttons or grommets can cause rust stains if they sit in the same position for a while and moisture gets trapped there. BTW: A "fridge pack" of baking soda tossed in the laundry basket can help prevent damage/stains caused by moisture. All of the above is the result of repeated OR experimentation. (Contract workers often stay away from their primary residence for extended periods. Catching up on the laundry beforehand isn't always an option. :-) 76.97.245.5 (talk) 23:41, 12 February 2009 (UTC)

I would expect no major problems after one or two weeks, but I'm not sure about periods longer than that. Even if clothes are damp, they usually dry out after about half a week indoors. As for rotting, clothes made from materials such as cotton would be more suceptible than polyester or nylon. I find that paper starts to rot after about one or two years, for comparison. Bacteria may start to grow on the BO, however, but they should be able to be washed off, and you could hand-wash it with hot water and soap if nessecary. If your clothes are clean but used, they should be OK for a couple of months. ~AH1^(TCU) 22:38, 13 February 2009 (UTC)

Uranus and Saturn's gravity

Why is Uranus' gravity usually less than Earth. Uranus and Saturn is much larger than Earth, so it's gravity should be like 1.05 and 1.20 at least. Some source said Saturn's gravity is 0.9 and Uranus is 0.85. And also how we know Uranus and Neptune have no solid surface when Voyager only look at it's clouds? Did Voyagers look at the bottom of the clouds?--216.100.95.90 (talk) 20:58, 12 February 2009 (UTC)

Gravity is about more than size; the strength of a planet's gravity is related both to the mass of the planet and the distance from the planet's centre. Uranus and Saturn are more massive than Earth but also have much greater diameters, and so are significantly less dense. - Eron^Talk 21:21, 12 February 2009 (UTC)

They'll have something solid if you go down far enough (or, at least, not gas any more). Uranus and Neptune may well have something not far off simple rock at their cores. Jupiter (and maybe Saturn) has such high temperatures and pressures once you go down far enough that you get weird stuff like metallic hydrogen, rather than a conventional solid. --Tango (talk) 21:32, 12 February 2009 (UTC)

Apparent surface gravity varies due to quite a few factors:

1) The mass and density of the planet are both important, as noted previously.

2) Since the material directly underfoot has a far greater effect than mass far away, local density variations are quite important, too.

3) The planet's rotation can cause an apparent reduction in the force of gravity (as opposed to an actual reduction). This will be strongest along the equator and have no effect at the poles.

4) The "atmosphere" on gas giants can be thick and dense enough to exert a significant upward gravitational pull, which must be subtracted from the normal gravitational pull to figure out the net amount. This would be much more of a factor if the "surface" on which the observer stands is solid rock underneath a liquid "ocean". StuRat (talk) 21:54, 12 February 2009 (UTC)

Assuming (as is fairly reasonable) that the atmosphere/ocean is distributed approximately spherically symmetrically, there will be no significant upward pull from it, by the shell theorem. Algebraist 22:05, 12 February 2009 (UTC)

Stop. The first question includes incorrect "information." Saturn and Uranus' gravities (ie masses) are not less than Earth's. The questiontioner should go back and check his source. Perhaps he is conflating "density" with "gravity." B00P (talk) 22:11, 12 February 2009 (UTC)

Our articles disagree with you (of course the exact value depends on where you arbitrarily declare to be the 'surface'). What's your source? Algebraist 22:15, 12 February 2009 (UTC)

Gravity does not mean the same as mass, your "ie" is wrong. Gravity is proportional to mass, but it also has other factors involved. --Tango (talk) 22:18, 12 February 2009 (UTC)

Actually, from sources and studies, Urnaus and Neptune is consider to have no solid surface level. all Jupiter, Saturn, Urnaus, and Neptune will have something solid if we go deep enough (but human will be crushed and cooked before they get to ano=ything solid.) My question is how will we know Uranus and Neptune have no solid surface between atmosphere and mantle, when they only see the clouds. I thought spacecrafts have seen somethig deeper than cloud decks of Jupiter and Saturn. From Urnausn and Neptune's mantle they call it ice, but it is superheated stuff to kill humans, when diamond decompose-this one I have no idea.--69.226.42.163 (talk) 23:38, 12 February 2009 (UTC)

We know their mass, size and some basic information about their composition (from spectral analysis and the like). Combining that with what we know of the laws of physics, we can make a pretty good guess about what's going on inside. --Tango (talk) 00:38, 13 February 2009 (UTC)

To answer your question of how scientists know Uranus and Neptune have no solid surface, they are not at all dense enough to be made out of rock. Density is a single calculation away once the mass and diameter are known. The mass of a planet can be easily determined from the strength of its gravity; the faster it makes the moons around it orbit, the more massive it must be. Diameter is directly related to how big (how many degrees) the planet appears to be at a certain distance. --Bowlhover (talk) 23:46, 12 February 2009 (UTC)

So the "Equatorial surface gravity" figures given in our articles (0.914g for Saturn; 0.886g for Uranus) are not really "surface" gravity at all, but are actually gravity at the visible top of the cloud deck. And in Saturn's case you have to make quite a hefty correction (about 15%) to account for Saturn's rapid rate of rotation - without this, the "surface" gravity would be 1.06g. So a more accurate description of these figures is "apparent equatorial gravity when co-rotating with visible surface of cloud deck". Gandalf61 (talk) 11:29, 13 February 2009 (UTC)

You should keep in mind that both Saturn and Uranus are less dense than Jupiter or Neptune. The density, along with the overall mass, contributes to the overall "surface" gravity. This exlains why Uranus's gravity is lower than Earth's, which Neptune's is just slightly higher. — Preceding unsigned comment added by AstroHurricane001 (talk • contribs)

what is Steve Baker's IQ? Why does he know so much?

What is Steve Baker's IQ? Why does he know so much? Does he know what he knows before answering the question, or do he do just-in-time (JIT) research, where he learns all that he says just prior to answering the question, through the Internet, etc? Is he a single person, or a syndicate?

Thank you! —Preceding unsigned comment added by 82.120.236.246 (talk) 21:24, 12 February 2009 (UTC)

If you want to know about Steve Baker, you should ask him. The rest of us can't really help you here. Algebraist 21:26, 12 February 2009 (UTC)

Steve Baker's IQ is as meaningless as anyone else's. I'm reasonably sure he's a single person (his writing style is definitely consistent, anyway). As for how he knows so much, you'll have to ask him - I suspect he answers questions the same way the rest of us do, a combination of personal knowledge and good research skills. But be careful - you don't want to inflate his ego too much or I'll have to go through the archives making a list of all his mistakes in order to bring him back down to Earth, and I don't really have time for that... --Tango (talk) 21:32, 12 February 2009 (UTC)

Aren't you tempting people to inflate his ego just to witness the drama? --99.237.96.81 (talk) 15:29, 13 February 2009 (UTC)

Tango: by single person did you intend unmarried or an individual? hydnjo talk 23:25, 12 February 2009 (UTC)

Individual. I try and use the same language as the person I'm talking to. The OP used "single person" to mean individual (as opposed to a syndicate), so I used the same phrase. Why would I have been discussing his marital status? --Tango (talk) 00:35, 13 February 2009 (UTC)

Dunno, just clarifying. I certainly agree that there are no signs that SB is a role account - none. hydnjo talk 00:49, 13 February 2009 (UTC)

Go and learn, and you will hopefully become as smart as Steve :) --Dr Dima (talk) 21:40, 12 February 2009 (UTC)

You don't have to research too hard to discover Steve's marital status [41]. He's a diamond geezer with platinum humour. He can sting you, teach you and make you laugh in one line. Whether he can drive well, Hmm...? Hope he's recovered. ;-)) Richard Avery (talk) 23:10, 12 February 2009 (UTC)

Hey...HEY....I was STATIONARY - my driving skills were irrelevant! SteveBaker (talk) 04:42, 13 February 2009 (UTC)

But you were stationary in the wrong place… Algebraist 18:15, 13 February 2009 (UTC)

IQ != knowledge--GreenSpigot (talk) 01:02, 13 February 2009 (UTC)

Of course, there does exist the possibility that Steve is actually a prodigious savant, where he knows and remembers all but his IQ is actually really low. Not that I think that's the case, just to outline the noncorrelation between IQ and knowledge/memory. bibliomaniac15 01:32, 13 February 2009 (UTC)

You can tell the he understands what he's talking about. You can easily tell when someone is reciting from memory without any understanding. --Tango (talk) 13:10, 13 February 2009 (UTC)

• This doens't matter if he is single or couple. These kinds of questions you do not ask users, it's personal (unless he writes it on user page). Doing so is stalking. I think he is extraordinarly intelligent, he is domineer on science. most of time, I don't even understand his post-I wish my IQ is like him, but to be like him, we have to have strong math, algebra and english art skills.--69.226.42.163 (talk) 04:04, 13 February 2009 (UTC)

• Don't be absurd. There's nothing wrong per se with asking users personal questions. If they don't want to tell you then they won't. Algebraist 18:15, 13 February 2009 (UTC)

Oh - Jeez - this is so embarrassing...but I have to be self-deprecating or Tango will go and find all of my many serious screw-ups! So this is "original research" of the worst kind!

My IQ is pretty good (I forget the score I got - but it's Mensa-level - which isn't saying that much actually) - but that's not it. IQ test scores only tell you how good you are at IQ tests.

I guess I have to reveal the trick to answering RD questions.

I read widely and I've been doing that since I was a kid and now I'm 53 years old. You should just look at the pile of books at my bedside from last month. When you do that - you end up knowing a little about an awful lot of subjects! Even more than that - from the relatively early days of Wikipedia back in 2004-ish, I decided to hit "Random article" three times every night before bedtime and NO MATTER WHAT to read every article that comes up (There are an AWFUL lot of Japanese railway stations!). So after four years, I've probably hit 'random article' and read about 1000 articles per year - maybe 4000 to 5000 articles. (And of course - sometimes I hit an interesting article and end up reading a lot of things leading from there - so probably the total number I've read is more like 15,000 to 20,000 - which is not a significant fraction of 'everything' - but it's a very BROAD look at everything we have here.

Answering questions (and reading answers) from the RD tends to make you read more deeply into areas where people commonly ask questions. Working on the RD also gives you another vital skill - the ability to Google. Quite often, knowing a little about a subject is just enough to let you find a better set of search terms than our original posters are able to do.

Combine that with the whole of human knowledge in an easily searchable form (Wikipedia and the Internet) and you can answer a broad range of questions because your little-but-wide knowledge allows you to at least know what to look for.

But I also have Asperger's syndrome. One attribute of us 'aspies' is that we are easily obsessed into doing deep-deep-DEEP research into a specific narrow area. If you are an OLD aspie (as I am) then you've probably gone through these obsessive research phases a couple of times a year since childhood. So there are probably 40 or 50 very narrow subjects that I'm truly a deep expert at. Computer graphics, Mini cars, puppetry, Lego, Software, Light and color perception...these things have been obsessions of mine for a long time - and every six months, there is a new one. Right now, I'm obsessed with tiny computers like the Arduino. Take the uber-obscure car the Mini Moke...it's a varient of the Mini and because I was trying to get the Mini article to front-page featured article status, I needed to understand the Mini Moke...but our article was just a tiny stub. So in order to write my Wikipedia article about the Moke, I bought and read every single book, repair manual, old magazine (thank-you eBay) and talked to every Moke owner I could find...now I'm something of a world authority on the car - although I've never actually owned or even driven one!

Nobody "in their right mind" does that...but that's what us Aspies are like...we're "nuts" by normal standards.

This means that on those 30 or 40 subjects I can give a really deep answer - which looks impressive when you happen to hit on one.

Very often, I answer questions by reading the relevent Wikipedia article - and merely distill and reword what it says to make it more comprehensible to our OP. You'll also notice that very often my reply is one of the last - and that's because I'm reading articles and Googling stuff that previous respondents actually already knew about...which is "cheating" - but useful to our OP's (I hope).

Being an Aspie means that I strongly dislike meeting people and going places - and the online 'world' is much more comfortable for me - so I spend a lot of time 'here'...that helps too.

So - there you go. No magic...just a thirst for knowledge and LOT of reading over a LOT of years.

SteveBaker (talk) 04:42, 13 February 2009 (UTC)

Exits stage left to loud applause. 86.4.190.210 (talk) 07:17, 13 February 2009 (UTC)

Being 53 is cheating... How am I supposed to stand a chance having only had 21 years in which to learn useless information? It's not fair... --Tango (talk) 12:10, 13 February 2009 (UTC)

Just look forward to how much you'll know at 53, what with direct brain-Wikipedia uplinks and such. Algebraist 12:45, 13 February 2009 (UTC)

Problem is, I'm an early adopter, so I'll probably get my brain fried with the beta version. I won't know anything by age 53! --Tango (talk) 13:09, 13 February 2009 (UTC)

Hey, I don't know if this is tiny enough for you, but there's an outstanding issue on the PSP article of whether the PSP's CPU is a 64-bit R4000 or a 32-bit 4K. I'm a software guy and not particularly knowledgable about non-PC hardware. The applicable reliable sources (this is a gaming system, remember) are reporting that it is a 32-bit architecture but an editor who is apparently knowledgable in this field is claiming that the reliable sources are wrong and that they have confused the difference between R4000 and 4K. This has led to two questions. 1) Are the reliable sources wrong? 2) If so, what do we do about it since Wikipedia's policy is about verifiability, not truth. The discussion is here: [42] A Quest For Knowledge (talk) 14:22, 13 February 2009 (UTC)

Maybe Steve has a photographic memory – GlowWorm —Preceding unsigned comment added by 98.17.32.201 (talk) 18:06, 13 February 2009 (UTC)

If such a thing actually exists... see Eidetic memory#Controversy. --Tango (talk) 18:12, 13 February 2009 (UTC)

See Eidetic Memory#People with eidetic memory. – GlowWorm.

I often remember things from books by associating the factoid with where it is on the page and what the headings and illustrations look like, so I will know that if I find the page with a picture at top-right and a light-purple heading halfway down, two paragraphs below that is the information I'm regurgitating. Maybe that's eidetic memory or maybe not, but it's how my own memory works and does me well. It would probably work for web pages too, but they keep changing the damn things and I can't hold them in my hands and stick my fingers in to flip back and forth. Hopefully they'll have a hand-operated web soon... Franamax (talk) 23:15, 13 February 2009 (UTC)

I do much the same. I can't actually read the text from my visual memory of the page, but I can see the general layout and know almost exactly where on the page the bit of information I want is (I notice this primarily when I can't actually remember the information - it's very frustrating!). --Tango (talk) 12:33, 14 February 2009 (UTC)

The computer manufacturers and software firms like to talk about "the paperless office". But somehow you can't seem to get along without the sheets of paper. So you use a computer where it works best, and paper where it works best. Fortunately, computers can do printouts, but you still need notepads and Post-Its. - GlowWorm.

My estimate of SteveBaker's intelligence and knowledge is approximately this number and I estimate his error rate at roughly four sigma, which is a pretty reasonable process efficiency. I would suggest that next time ToaT updates the statistics on answers, we get a separate section on how often and quickly the SteveBaker answer appears, since it is usually the comprehensive and definitive one. (And regardless of SB's intelligence level, for me they are among the answers I anticipate the most, similar to BenRG's discourses on cosmology, and a few different really good physiology answerers). We really do have some heavy hitters here, to me IQ matters much less than the quality and depth of the answers and the amount I learn by reading them! Steve does need to learn how to pop the clutch and get out of the way of large vehicles in a hurry though. :) Franamax (talk) 23:33, 13 February 2009 (UTC)

I was with you until "Steve does need to learn how to pop the clutch and get out of the way of large vehicles in a hurry though"... I'm afraid I don't follow this metaphor.. :( —Preceding unsigned comment added by 82.120.236.246 (talk) 02:18, 14 February 2009 (UTC)

It's not a metaphor. I was in a pretty nasty car wreck on sunday - rear-ended by a HUGE pickup truck...and indeed if I had teh wikkid drivin' skillz, I could have slipped the tranny into 1st, popped the clutch and redlined my way to safety. SteveBaker (talk) 04:23, 14 February 2009 (UTC)

We'll just ask JPL to send over some airbags for you and you'll be fine next time. :-) 76.97.245.5 (talk) 07:28, 14 February 2009 (UTC)

Next time

Steve, recalling a thread from a little while ago, that's another reason why I keep my car in gear with the pedal-brake depressed while stationary on the road - one less thing to do when I decide it's time to get out of the way, I just step on the gas and drop out the clutch. Luckily I've only had to use that technique when I see emergency vehicles approaching from behind, so far knock on wood. Now, Texas driving stories, and a horrific accident I witnessed and tried-but-not-rescued in Dallas, involving a large pickup truck - good to have you posting just like normal, brain apparently intact. And BTW, did your airbag deploy? (And yeah, it's Texas, I'm betting that you're fully liable for getting in the way of the 4 other cars whose forward progress you impeded - keep it in gear next time and bolt when you see it coming in your mirrors, that's what a manual tranny is made for!) Franamax (talk) 07:57, 14 February 2009 (UTC)

February 13

Post-It Note adhesive Thickness

I just got back from a trade show, and one of the bits 'o swag was a "brick" of Post-It Notes, about 2-3/4 inch (70cm) thick.

All the notes have the adhesive on one edge. It's a continuous strip of adhesive on each sheet, about 3/4 inch wide, and the paper is about 2-3/4 x 2-3/4 inch, making the brick almost a perfect cube.

I would have expected the thickness of the adhesive to be obvious along the adheded (is that a word?) edge. However, the cube looked flat. So I got out my Mitutoyo CD-6"P calipers, and took some measurements. 10 sheets measured .0415", making each sheet 4.15 mils thick. The thickness of the brick was 2.7815", meaning that (rounding off here) there were 670 sheets in the brick.

Now I admit that the caliper measurements aren't perfectly repeatable, since I can't calibrate the force I use use when making a measurement. But I was unable to detect any difference between the thickness of the adheded (there it is again) edge, and the plain edge.

If we assume that the thickness of the adhesive was a millionth of an inch, that would make a difference of .67 mils over the thickness of the brick, which would be just detectable using this crude instrument.

I find it hard to believe that such a thin coating is possible, but I hold the evidence in my hand. I checked the Wikipedia article and Googled around trying to find out the thickness of the adhesive layer with no luck. Any of y'all have an idea where I can get that information? Thanks. Bunthorne (talk) 00:03, 13 February 2009 (UTC)

oh my god do I envy the kind of time you seem to have!!! 82.120.236.246 (talk) 00:20, 13 February 2009 (UTC)

Well, you know, I don't think this took him more than five minutes with the calipers. -- Captain Disdain (talk) 02:37, 13 February 2009 (UTC)

and writing the above? and rumination ? —Preceding unsigned comment added by 82.120.236.246 (talk) 03:53, 13 February 2009 (UTC)

You're right, it was a downright Herculean effort. How did he find the time?! -- Captain Disdain (talk) 08:56, 13 February 2009 (UTC)

Once you start looking at scales of a millionth of an inch, the surface of a piece of paper is anything but flat. --Carnildo (talk) 01:44, 13 February 2009 (UTC)

Does the micro-weight of the sticky area vs non-sticky come into it? Julia Rossi (talk) 01:58, 13 February 2009 (UTC)

Micro weight maybe not, but macro weight they flatten the block under while producing (cutting) it. You can buy this Postit type adhesive in a spray can. Other than glue or the sticky stuff on the back of Duct tape, this type of adhesive doesn't add much if any bulk. The material will try to "even out" when pressed and so the fibers sticking out of the non adhesive part will not be depressed as much by comparison as the part with the sticky layers. 76.97.245.5 (talk) 04:09, 13 February 2009 (UTC)

Here's a side issue on this topic. The chemist at 3M who invented the Post-It adhesive was trying to develop a powerful new glue. When he came up with a weak adhesive, his cohorts laughed at him and made him the butt of jokes. However, he had the last laugh. – GlowWorm —Preceding unsigned comment added by 98.17.32.201 (talk) 18:17, 13 February 2009 (UTC)

It's interesting to note that the post-it 'brick' that I have has alternate sheets glued at alternate ends to form a 'zig zag' of sheets. I wonder whether they did that specifically to circumvent the theoretical difficulty that our OP mentions when (possibly) using less absorbant paper or something? SteveBaker (talk) 21:20, 13 February 2009 (UTC)

The alternating post-it brick is used for a post-it dispenser. If all the sheets are glued on the same side, when you pull one out the top, it will lift the whole brick, come loose, and then you'll have to hand-feed the next sheet through the slot on top. If they alternate, pulling one will lift the next sheet through the slot at the top before separating from it. -- kainaw™ 21:27, 13 February 2009 (UTC)

It's probable that the adhesive and paper are sufficiently compressible so that the "adheded" edge is of the same thickness as the uncompressed, paper-only parts of the block. As the OP mentions, "compression" force resulted in a slightly non-repeatable measurement by calipers. Though it's hard to imagine, the individual sheet of paper probably squeezes into a perfect little rectangular prism of fairly uniform thickness (height?), even though there is more material on the "adheded" edge. (Alternatively, there could be slightly thinner paper on the "adheded" side, but this would be really hard to manufacture).

Now, to verify my original assumption, you could probably perform an experiment to slice the cube into only-paper and paper-plus-adhesive blocks. Measure the mass of these, and calculate the excess mass which must be due to the adhesive. I think that there will be a serious signal-to-noise problem, bordering on the un-measurable, but for the sake of science... we must try. Nimur (talk) 18:51, 14 February 2009 (UTC)

I'd love to try Nimur's idea, which borders on genius, but the only instrument I have to measure mass is a bathroom scale. I could probably weigh myself holding the subjects, but I'm afraid the closest reliable reading is +/- 2 pounds, so I'd have to get either a somewhat better scale, or a massive number of bricks. Thanks for the ideas. Bunthorne (talk) 05:24, 15 February 2009 (UTC)

Tesla, Edison, Einstein and Asperger syndrome.

Just out of curiosity, did Tesla, Edison and Einstein all had Asperger syndrome? I read that somewhere and I was wondering if it's true. Thanks in advance. ― Ann _{( user | talk )} 00:41, 13 February 2009 (UTC)

Well, Hans Asperger first described what has since become known as Asperger syndrome in 1944, a year after Tesla died and 13 years after Edison died. Einstein died 11 years after that first description, but still well before the term "Asperger syndrome" was first popularised in 1981, and even longer before it become a common diagnosis. So, anyone saying any of them had Asperger syndrome is making, at best, an educated guess based on historical accounts. To get any kind of reliable diagnosis requires an intentional assessment of a wide variety of qualities. --Tango (talk) 00:52, 13 February 2009 (UTC)

I've read a couple of biographies of Einstein and he does have a lot of the attributes of an Asperger sufferer. Comparing his story to the criteria in DSM IV, he pretty clearly could be diagnosed that way on the basis of the information in his bio's. I don't know enough about Edison or Tesla. It wouldn't surprise me if Tesla was and Edison wasn't...but I really don't have enough information. SteveBaker (talk) 03:55, 13 February 2009 (UTC)

It's tough to apply diagnoses backwards in time—heck, it's not even easy to apply them to real, living people! Einstein's a tough nut to crack in particular because everyone sees him as what they want to see him as... --98.217.14.211 (talk) 16:52, 13 February 2009 (UTC)

I agree. But from the DSM IV description, I think Einstein can easily be shown to have had:

• A2) Failure to develop peer relationships appropriate to developmental level.
• A3) Lack of social or emotional reciprocity.
• B1) Encompassing preoccupation with one or more stereotyped and restricted patterns of interest that is abnormal either in intensity or focus.
• C) Significant impairment in social, occupational or other important areas of functioning.
• D) No delay in aquisition of language as a child.
• E) No delay in cognitive development.
• F) Criteria for Pervasive Developmental Disorder or Schizophrenia NOT present.

A2—the man had plenty of friends, lovers, etc., throughout his life. A3—the man was a life-long activist for the suffering, wrote passionately on the subject, got denounced by the Nazis and a 1,000 page FBI file for his troubles. B1—how exactly where his patterns of interest restricted? Patent examiner, theoretical physicist, social activist, violinist, writer, lecturer, etc.? C—what was so impaired? Are we just using the "Einstein was a weirdo" stereotype here, or are we basing this on his actual life and interactions? D,E,F—a lack of something abnormal seems hardly relevant here?

As with anybody as "iconic" as Einstein there is an elaborate mythology and stereotypes of his behavior that have percolated throughout culture. The idea that Einstein had his "head in the clouds" and thought of nothing but physics is plainly false (it is easy enough to see if one reads his collected essays—the man had tons of interests, was extremely cultured, was very "down to earth" on a wide variety of things).

My point in being contrarian here is not to make strong statements about Einstein, but to point out that each of those criteria are extremely subjective. Even in a living, breathing, non-famous person they can be quite ambiguous in everything but the outlier, extreme cases. With a historical figure around which an expansive mythology has been built—one that is demonstrably not even close to being accurate, like the one of Einstein as being a spaced out mystic old grandpa—it seems rather impossible to me to make a retrospective analyses unless of course they are one of the outlier cases (and Einstein doesn't seem to be one of those). For example, the fact that Einstein was a subversive civil rights activist and an unapologetic socialist is something that has long been underemphasized, as it for decades made people politically uncomfortable (even today, while his civil rights work is now much more paid attention to, his socialism is downplayed, though it is clear it was important to him for most of his life). He's not as simple as the caricature of him makes out. --98.217.14.211 (talk) 19:23, 13 February 2009 (UTC)

Where do people get this idea that Einstein had Asperger's? Never mind a detailed look through a list of symptoms, who would ever come up with this idea in the first place? It seems to be based on nothing more than the idea that smart people must be "different from the rest of us". People seem shocked that a smart person might go to clubs or be a surfer or womanize. The perception of intelligence as a kind of mental abnormality is a threat to the future of the human race. We should be fighting these nonsense diagnoses, not entertaining them. -- BenRG (talk) 13:56, 14 February 2009 (UTC)

Indeed. Asperger's is a very fashionable diagnosis at the moment, and it's common for people (not doctors, so much, they know a little better) to diagnose every smart person that has difficulty making friends as having it. I'm a smart person that has difficulty making friends, I do not have Asperger's (I was tested for it). I put my difficulty making friends down to two things, difficulty finding people I have something in common with (that gotten easier as I've moved up through education, there are plenty of smart people around once you get to Uni), and the fact that I was bullied in school because of my intelligence and as a result I tend to be quite closed off emotionally (a couple of pints helps with that!). I expect those reasons apply to a large number of smart people. (I should make it clear, I do have plenty of friends, it's just difficult to form that initial bond.) --Tango (talk) 14:20, 14 February 2009 (UTC)

The initial bond thing is key here. If someone struggles to make friends, but once made, can chat away easily with them, then the person probably has trust issues _{(awaits big pharma companies to start pushing oxytocin reuptake inhibitors or the like).} If the person just cannot empathise with people and doesn't chat to those they know well, then it is more likely Asperger's. --Mark PEA (talk) 12:40, 15 February 2009 (UTC)

comb attracting little pieces of paper

Classic physics example: A comb that's been rubbed can attract little pieces of paper. The explanation I've read is that the comb becomes charged, and it causes the neutral paper's atoms to be polarized. The positive ends of the atoms in the paper are attracted to the negatively charged comb. But that doesn't seem to make sense, because the negative ends of the atoms would equally be repelled by the paper. Since there are equal #s of negative and positive on the paper, shouldn't there be zero movement (no attraction/repulsion)? Also, the paper sometimes are repelled? Why? Thanks in advance. 128.163.224.222 (talk) 03:38, 13 February 2009 (UTC)

I can't really recommend our pages Static electricity and Triboelectric effect. The simple Wikipedua version is shorter, but I can't say I find it more enlightening [43]. Nevertheless you might find them useful. 76.97.245.5 (talk) 04:25, 13 February 2009 (UTC)

Similarly to the recent question about Saturn's gravity, the answer lies in the fact that the electric charge is only one of the factors governing the strength of the electic force. The other factor is the distance. As the negatively charged comb atracts the positive charges in the paper and repells the negative ones, those charges separate and the positive charges come closer to the comb. That way the atractive force becomes stronger than the repulsive force and the paper ends up being atracted. Dauto (talk) 05:52, 13 February 2009 (UTC)

I think something like that would be good on our pages. Would s.o. have the time to write it up? 76.97.245.5 (talk) 08:29, 13 February 2009 (UTC)

That doesn't make sense to me. If the comb attracts the positives, it should repel the negatives an equal amount for a net of zero. I thought that the presence of the electrons on the comb (or absence, I don't know which) would make it have a net charge with respect to, well, the rest of the universe, basically. Let's say the comb has excess electrons (it doesn't matter); the paper bits would have a positive charge with respect to the comb and would be attracted. A pile of lead shot would be equally attracted to the comb but would be too heavy to be lifted or even moved by the feeble forces involved. --Milkbreath (talk) 13:21, 13 February 2009 (UTC)

If the comb has excess electrons, they will repel the electrons (it's the electrons that are mobile) in each bit of paper. So the electron cloud around each atomic nucleus in the paper is very slightly displaced - it is no longer centred on the nucleus. The net effect over the whole piece of paper is that there is a slight deficiency of electrons nearest the comb and a slight excess furthest away. Force dimishes as the square of the distance, so the attraction of the positive end of the dipole is greater than the repulsion of the negative end. Philip Trueman (talk) 13:31, 13 February 2009 (UTC)

If I remember correctly, it's called electrostatic induction. (Just giving a name to Philip's explanation) --Bennybp (talk) 13:57, 13 February 2009 (UTC)

Further proof that I'm seriously stupid. If the comb is pushing the electrons in the paper away, that force is pushing the paper away, or those electrons would go right back where they were. The reason that that force doesn't make the paper move away is that the now-exposed positive charges attract the comb, for a net force of zero. I must be thick as a brick. --Milkbreath (talk) 14:31, 13 February 2009 (UTC)

The comb will now actually attract the paper, since now the positive charge is closer to the comb, and the negative charge is farther away (Coulomb's Law). I've never seen it done with a comb and paper, but balloons (one charged will actually attract a neutral one). --Bennybp (talk) 16:22, 13 February 2009 (UTC)

Syndrome or Disorder?

In order to respond to our previous question about Asperger syndrome and Einstein - I looked up the precise symptoms in the 'DSM IV' (which is the 'bible' of psychiatric diagnosis).

Why is it that DSM IV describes Asperger's as "Asperger's Disorder" and not "Asperger's Syndrome" as everyone else seems to do? Is there some important difference between a "Disorder" and a "Syndrome" in psych terminology?

SteveBaker (talk) 04:01, 13 February 2009 (UTC)

In technical discussions, a "disorder" or "disease" refers to the underlying condition or malfunction, while a "syndrome" refers to a collection of co-occurring symptoms or signs. A syndrome need not have unique cause, as the same constellation of symptoms might be caused in multiple different ways. In practice, the distinction may be abused or ignored, especially since many syndromes actually do only point to one unique cause. Dragons flight (talk) 04:16, 13 February 2009 (UTC)

So DSM is saying that Asperger's has a single underlying cause? Interesting. SteveBaker (talk) 04:50, 13 February 2009 (UTC)

Not quite, it's thought to have seveal underlying causes. We're just not entirely sure what they are yet, most likely genetics. —Cyclonenim (talk · contribs · email) 07:39, 13 February 2009 (UTC)

Well, that's what I thought - so back to the original question: Why 'disorder' and not 'syndrome'? In fact - a quick skim of the DSM IV index suggests that they never call anything a 'syndrome'. On the other hand we have 'AIDS' which is a syndrome (that's what the 'S' stands for). SteveBaker (talk) 08:05, 13 February 2009 (UTC)

I was doing a project for a client that had me read up on a medical topic. I then started work on a related wikipedia page and after a while was happy if I had a term where there were not at least 2 different versions describing the same thing with factions warring whose term was the better one. (First prize went to 5 varieties for one item.) Mental disorder and Classification of mental disorders say there are two accepted systems ICD and DSM. So maybe they are using different terms to reflect different views. Or they're just defending their turf. 76.97.245.5 (talk) 08:47, 13 February 2009 (UTC)

There's a desire in the community at large to "de-perjorify" language in an imprecise way. The word "disorder" implies a negative thing, that there is a normal (i.e. order) way to be, and that if you have a condition, that condition represents a "dis"-order, i.e. not normal, i.e. you are broken. Over time, there has been a trend in society to change the terms to remove distinctions that imply "brokenness" or "less than normalcy" for all sorts of conditions. Consider the spectrum of terms: mentally retarded-slow-mentally handicapped-mentally challenged-mentally different-exceptional. Over the past 30 years or so, these terms have been used to describe the exact same set of conditions in an individual. Look at the early end of the spectrum compared to the modern term, "exceptional". Exceptional even sounds like its a benefit. Does little Joey have a learning disability? No, he's "exceptional". Same deal with disorder vs. syndrome. A disorder implies that something is broken that requires modification in order to work. A syndrome merely sounds like a set of differences that requires no intervention. We need to fix a disorder. You need to learn to live with a syndrome. The medical professionals who wrote the DSM IV sound like they aren't necessarily caving to political pressures to use imprecise or cuddly language. These are real problems, and require real interventions in order to help people cope with them. Asperger's is not like being left handed; it's not a neutral condition with regards to how people interact socially in the world, and it requires serious minded people who are willing to approach it in a way that helps people who have it integrate in the world in a meaningful way. Changing its name does not change the need to deal with it properly. --Jayron32.talk.contribs 17:24, 13 February 2009 (UTC)

Hmmm. Somehow I doubt that all (or even most) people with Asperger's would agree that their condition is something that "needs to be fixed". Gandalf61 (talk)

Indeed no! I'd be violently opposed to anyone trying to 'fix' my Asperger's - for me, the benefits outweigh the losses. Not all aspies feel that way though. I wouldn't object to 'disorder' though - there is definitely something wrong with my brain - it's just that the consequences of that 'wrongness' are a mixed bag of benefits and down-sides. What I would wish for is MUCH earlier detection - and proper training to help aspies know what their limitations are and how to work around them. I didn't find out until maybe 10 years ago - and knowing what I know now, I just cringe at some of the things I totally screwed up as a kid and young adult. SteveBaker (talk) 17:56, 13 February 2009 (UTC)

Is there anybody without a 'disorder' at that rate? Just because a greater percentage of people do a thing doesn't mean it is the better way. For instance it is quite normal to get in a huff when criticized and ignore any practical lessons that there might be. It is quite normal to follow a leader and do what they do even if it is wrong and bad. Yes normal is a whole mixed bag of contrary ways of doing things, social anthropology may be a bit unscientific but appealing to the behaviour of bunches of ape men in caves seems about the best explanation. I wonder though what types of people the future belongs to. Dmcq (talk) 10:06, 14 February 2009 (UTC)

asexual reproduction

is it possible (for women) to reproduce asexually using the power of the mind alone? If so, are there any documented cases? If not, what physical constraints in the human body would prevent this effect? Thank you. —Preceding unsigned comment added by 82.120.236.246 (talk) 05:34, 13 February 2009 (UTC)

Short answer: NO. A woman's body cannot produce the sperm necessary to fertilize one of her eggs in order to create a diploid cell. Other dipoid cells of the woman's body do not have the right genes activated in order to start a new embrio. Dauto (talk) 05:58, 13 February 2009 (UTC)

Not in humans (although I'm not sure if it's technically impossible) and definitely not related to the power of the mind, but see parthenogenesis. Zain Ebrahim (talk) 09:07, 13 February 2009 (UTC)

Also see the section Wikipedia:Reference_desk/Science#Same-sex_gametes_combining_to_form_a_zygote.3F. Mammals take two to tango. Even those genetically modifed mice that let you make a viable embryo out of two eggs doesn't make asexual mammals possible. Someguy1221 (talk) 09:18, 13 February 2009 (UTC)

Fingerprints

i always had doubts about this ..is it an absolute truth that finger prints are unique for each one , isnt been recoreded even for once that two indivisiuals has the same finger print , and when was the first time this finger print thing was mintioned ..??????? —Preceding unsigned comment added by Mjaafreh2008 (talk • contribs) 11:20, 13 February 2009 (UTC)

Have you read Fingerprint#Validity_of_fingerprinting_for_identification? 130.88.151.87 (talk) 11:31, 13 February 2009 (UTC)

It depends on what level of accuracy you look at. Have there ever been two fingerprints from different people which were exactly alike ? Probably not. Have there been two different prints which were close enough to be mistakenly taken to be the same print ? Absolutely. This is especially true if fingerprints are smudged or partial, as they frequently are at crime scenes.

Another factor that comes into play is use of fingerprint databases. Let's say that a match can be found with only a 1 in a million rate of misidentification of the wrong person. If fingerprints are used to compare a crime scene print with a suspect seen leaving the premises around the time of the murder, then it's very unlikely the print will be found to match if it doesn't. So, that's a good usage. But now let's imagine that nobody was seen leaving the scene, and instead they run the print against a database that contains millions of fingerprints. With that 1 in a million failure rate, you'd expect one or more to match, just based on chance. Arresting such a person, based solely on their fingerprint, would not serve justice. Investigating people further who match might make sense, though. If one of them was an acquaintance of the murder victim, and has a record of performing similar murders, then an arrest would make sense. StuRat (talk) 15:52, 13 February 2009 (UTC)

WILL ... mabey op should look in the link he listed beforehttp://www.metacafe.com/watch/98111/miracles_of_the_quran_12/ i dont think this is a coincidence too , dont you think —Preceding unsigned comment added by 94.249.98.74 (talk) 19:36, 13 February 2009 (UTC)

The article cited above on validity and reliability of the method noted that the FBI incorrectly said there was a match between the prints of an innocent man (as later determined) and prints left by a terrorist bomber. The validation of the methodology has apparently been mostly by handwaving assertions rather than scientific and objective testing. Edison (talk) 01:00, 14 February 2009 (UTC)

Note that many of the failings of fingerprints can also apply to DNA testing. That is, while both prints and DNA are supposedly always unique (although, in the case of identical twin DNA, you'd need to look in great detail to find mutations, etc.), they can both still fail to identify, with either false positives or negatives, for similar reasons:

1) Poor quality prints or degraded DNA can both result in people declaring a match, when they really don't have enough data to say with any certainty.

2) Both are subject to simple human error, like accidentally submitting the same sample as if were both prints/DNA samples, resulting in a false match.

3) Both are subject to the expert lying on the stand about there being a match, due to bribes, pressure from the prosecution, threats from the defense, etc. Prints aren't quite as bad, in this respect, though, as jurors are more able to judge for themselves whether a match exists (provided they are actually shown the correct samples). StuRat (talk) 14:46, 14 February 2009 (UTC)

Snowflake symmetry

Why are snowflakes symmetrical? How does one leg know to become exactly like the others? --Milkbreath (talk) 12:04, 13 February 2009 (UTC)

I think the answer (i.e. I read it somewhere once - but here's a link) is that in general they aren't: it's just that the pretty symmetrical ones are those whose photos get into the books. AndrewWTaylor (talk) 13:02, 13 February 2009 (UTC)

Indeed. Our article on snow says "The most common snow particles are visibly irregular, although near-perfect snowflakes may be more common in pictures because they are more visually appealing". Gandalf61 (talk) 13:18, 13 February 2009 (UTC)

I've looked at a lot of snowflakes over the course of a life lived mostly at 40 North. When you do get individual snowflakes, they are quite regular. I don't know what those articles are talking about. But, leaving that aside for the moment, let me rephrase the question: In the not uncommon snowflake that in gross structure is radially symmetrical, what forces are at work in creating the symmetry? How can one leg know what the others are doing, so to speak? --Milkbreath (talk) 13:28, 13 February 2009 (UTC)

See http://www.sciam.com/article.cfm?id=why-are-snowflakes-symmet Cheers.--Fuhghettaboutit (talk) 13:42, 13 February 2009 (UTC)

Good link. So, nobody knows. I can live with that. --Milkbreath (talk) 14:37, 13 February 2009 (UTC)

I don't think there is any mystery here. The six branches of the snow flake presumably grow radially outwards at the same rate, and the length and breadth of side branches or plates depends on the temperature and humidity that the snowflake is experiencing at a given point in time, so it is not surprising if all branches show similar sequences and patterns of side branches. Observer bias then makes us focus on the symmetries and ignore the imperfections. If you look closely at the photographs here or here or even in the iconic Wilson Bentley photographs, you see that the symmetry is far from perfect. Gandalf61 (talk) 15:20, 13 February 2009 (UTC)

I think we know. The core ice crystal is hexagonal - as the crystal is swirled around inside the cloud, it accretes more ice until it becomes too heavy to stay inside the cloud and then falls to earth. In general, whatever humidity/temperature/pressure changes happen to one face of the crystal happen identically to the other five faces - so however one side grows, the other sides tend to grow the exact same way. What makes them slightly asymmetrical is that the conditions may not be PRECISELY the same on all six arms and also, sometimes they are damaged by collisions with other snowflakes. SteveBaker (talk) 15:30, 13 February 2009 (UTC)

(ECx2) They gave a good explanation, the same one I thought of:

1) Different temp/humidity combos result in many different types of branching.

2) Since the conditions are likely to be identical on all sides of the flake, the branching is likely to be the same on all sides.

3) When temp or humidity do change, during snowflake formation, the type of branching changes on all sides of the flake. The result is a complex, yet symmetrical, formation.

4) So, then why are so many not symmetrical ? I suspect that collisions are the main culprit, allowing flakes to break or stick together.

It also seems to me that this is part of a larger question: Why do crystals, under ideal conditions, tend to form symmetrical shapes ? The explanation would be similar to that for snowflakes. StuRat (talk) 15:33, 13 February 2009 (UTC)

Why are snowflakes flat? Most crystals have substantial amounts of material in three dimensions. Does the thickness vary in different snowflakes? Are there bumps or other extrusions on the flatness that vary in size and placement in different snowflakes? If there are bumps, do they form a pattern, perhaps hexagonal? Has anyone photographed, or even examined, snow flakes viewed on edge? – GlowWorm —Preceding unsigned comment added by 98.17.32.201 (talk) 17:08, 13 February 2009 (UTC)

One of the links Gandalf61 posted lists a variety of snowflake types, many of which are far from flat. Depending on the temperature the snowflake forms at, it may grow primarily along the c-axis ("vertical"), and come out as something like a thin needle; or it may grow primarily along the a-axes, and come out flat. Take a look at the morphology diagram here. Also, snowflakes generally don't form at constant humidity and temperature — so for instance if one starts forming at a temperature that drives c-axis growth, then (because of a temperature change) switches to a-axis growth, you'll get something like a capped column. -- Speaker to Lampposts (talk) 08:07, 14 February 2009 (UTC)

I missed that link. I'll order a couple of those books. – GlowWorm. —Preceding unsigned comment added by 98.17.32.201 (talk) 10:16, 14 February 2009 (UTC)

Was Banting really the first to discover insulin?

People in Romania believe otherwise !They say it was Palescu!(Ramanathan) —Preceding unsigned comment added by 212.247.70.129 (talk) 13:22, 13 February 2009 (UTC)

And was it Best or MacLeod who shoudl be credited as his partner in discovery?(Ramanathan) —Preceding unsigned comment added by 212.247.70.129 (talk) 13:24, 13 February 2009 (UTC)

Our article insulin says that Nicolae Paulescu was the first to isolate insulin, both those articles, and the references cited in them, should be of interest to you. DuncanHill (talk) 18:06, 13 February 2009 (UTC)

Freemartin

What does the term freemartin mean relating tocattle prodution and what causes this condition ? —Preceding unsigned comment added by 66.244.104.243 (talk) 16:26, 13 February 2009 (UTC)

Have you found our article freemartin yet? DuncanHill (talk) 18:03, 13 February 2009 (UTC)

Faster-than-light communication idea

I believe physicists that nothing can travel faster than light, c, at 300,000 m/sec. But what nothing actually had to move for something meaningful to be transmitted superluminally?

Here's my idea: (see picture here) A giant rigid cylinder made of super-strong material extends between two points in space that are one light-year apart, A and B. (Disregard the engineering infeasibility, gravitational influence of stars, galaxies, dark matter, etc.) At each end of the light-year long cylinder is a wheel with a peg to turn it. Initially, the peg at A is exactly at A and the peg at B is exactly at B. If I turn the peg from A to A', how long does it take for B to go to B'?

I see two possible outcomes:

1. Holy cow it's the answer to superluminal communication! (unlikely)

2. The rotation from the A end of the cylinder will "travel" across to point B over time, probably taking a little more than a year.

What do you folks think? —Preceding unsigned comment added by Marskid2 (talk • contribs) 16:57, 13 February 2009 (UTC)

Sorry. -- Coneslayer (talk) 17:03, 13 February 2009 (UTC)

(EC with coneslayer. I will assume his answer was similar to this). In any real material (i.e., one made of atoms which obey the laws of physics in this known universe) there is no such thing as a "rigid" cylinder. Rigid is only relative, and at the sizes you describe, there will be some deformation along the rod. When you turn A towards A', the rod in the middle begins to twist torsionally. Think if you had a piece of clay in your hands, and held one end steady while the other end you twisted. The rod will do the same thing. Now, over time, the "twist" will travel down the rod towards B, however this obviously will occur at some rate slower than the speed of light, the movement of A towards A' will not occur at the B side until the "twist" arives there. Thus, the laws of the universe are safe from giant imaginary rods. --Jayron32.talk.contribs 17:12, 13 February 2009 (UTC)

Ah that makes sense now. I definitely didn't realize how big of an assumption "rigid" was. Thanks for the quick answers! =) marskid2 (talk) 17:15, 13 February 2009 (UTC)

To elaborate a bit further: Your rod's stiffness is caused by chemical bonds, i.e. electromagnetic forces. These are communicated via photons. So any disturbance of the rod can at most travel down it at the speed of photons (i.e. the speed of light). --Stephan Schulz (talk) 17:26, 13 February 2009 (UTC)

Is anyone collecting these? In the past few years, I've seen suggestions that we use long ropes, metal bars, crystal rods, long nano-tubes... etc. I'm waiting for "What if we used a really long fish?" -- kainaw™ 19:07, 13 February 2009 (UTC)

We already know the whole idea is fishy, these are just specific variations. DMacks (talk) 19:21, 13 February 2009 (UTC)

Here [44] is a fish-powered perpetual motion machine. You have to scroll through dozens and dozens of other ideas but eventually:

"If we made a fishing rod with a tiny motor-battery combo, and it would cast out til it caught a fish, and the fish when caught was pulling against the motor til it ran backwards and recharged the battery for the next cast, we would have made another perpetual activity er motion. It would, of course, have to sense the battery charged up & generate a lure-release."

(You can tell it's a crackpot site because it's using LOTS of color/italics/underlining)

SteveBaker (talk) 21:06, 13 February 2009 (UTC)

To give him credit I think it lost something in translation from the original schizophrenia. --98.217.14.211 (talk) 04:53, 14 February 2009 (UTC)

I had a tube full of marbles yesterday. --Carnildo (talk) 00:51, 14 February 2009 (UTC)

I thought I had one also, but everyone says I lost mine years ago... DMacks (talk) 01:52, 14 February 2009 (UTC)

Just for the record, the speed of light is about 1000 times faster than what you said. :) -- Aeluwas (talk) 16:55, 14 February 2009 (UTC)

Indeed. I expect the OP meant km/s. --Tango (talk) 17:38, 14 February 2009 (UTC)

Just to answer Marskid2s original scenario, the torque on the cylinder will travel along its length at the rate of shear waves in the material, which is a little less than the rate of (longitudinal) sound waves. Assuming the cylinder is made of steel, for which the speed of sound is about 5930 m/s, the twist will travel from one end of the light-year long cylinder to the other in a little more than 50,600 years. --Chetvorno^TALK 07:10, 15 February 2009 (UTC)

PROPELLER ENGINE VS JET ENGINE AT HIGHER ALTITUDE

IS THERE MATHEMATICAL PROVE FOR DECREASE IN PROPELLER ENGINE EFFICIENCY AT HIGHER ALTITUDE IN COMPARISION TO JET ENGINE —Preceding unsigned comment added by 114.31.179.11 (talk) 18:34, 13 February 2009 (UTC)

First, typing in all caps is the equivalent of screaming at everyone. Would you walk into a library's reference desk and immediately start screaming at the poor woman behind the counter?

Second, check Newton's laws of motion. How does a propeller work? It forces air in one direction, causing the propeller to move in the opposite direction. If there is less air, there is less are to move. How does a jet engine work? Fuel is placed into a confined area. Combustion causes thrust to escape. The thrust is channelled in a specific direction, causing the engine to go in the opposite direction. The air is not used, fuel combustion is. If you take oxygen with you, you can continue using a jet engine at any altitude you like, but a propeller engine will fail at rather low altitudes for aircraft flight. -- kainaw™ 19:04, 13 February 2009 (UTC)

I don't think it is necessary to be quite so sniffy with people who type in all caps. Its not really the same as shouting in a library and their typing skills may not be as good as yours. SpinningSpark

Most people mean by jet engine a turbofan engine as used on commercial aircraft. These engines require an air intake for the compressor and have a definite altitude limit. Although technically the term includes rockets which carry their own oxidizer I think the OP probably meant turbofan. You can find a comparison of the altitude records for both types of aircraft at Flight altitude record. Both types will lose efficiency as air density decreases but I don't think you are going to find a simple formula to compare them as it depends on many aircraft design factors. SpinningSpark 22:47, 13 February 2009 (UTC)

2009 satellite collision relative velocities

Hi guys. I'm trying to add some detail to 2009 satellite collision and I'm looking for reliable sources on the relative velocities of these satellites. I've found a few sites [45] but these are "amateur" estimates fraught with speculation. Has anyone got any good sources for the relative velocity of the strike? Nimur (talk) 19:47, 13 February 2009 (UTC)

This forum seems to use more rigorous math to ge 3.4 km/s. Still hardly a reliable source. Nimur (talk) 19:57, 13 February 2009 (UTC)

I do not understand why the relative velocity would be so high (26,000 mph per the article, or een the 3.4 km/sec estimate above). If they were in circular orbits at the same height, and in the same orientation, the relative velocity should be zero. In a given orbit, satellites could be placed at the same height and orientation, spaced around the earth. Eccentricity of orbit would introduce some relative velocity. Orbits at different orientation would introduce additional velocity. Why would the launching countries place satellites in conflict orbits, where high speed collisions are likely? If a satellite is defunct, shouldn't the launching country be responsible for controlled de-orbiting (by retrorocket on board or by their or others' robotic deorbiting mission? Isn't there some coordination of orbits, to avoid the proliferation of long lasting space junk in valuable orbits, like airliners do not fly around willy-nilly ? Is there the likelihood of this debris hitting other satellites and causing even more hazardous space junk? These orbits are high enough that the junk might not reenter for a very long time. Edison (talk) 00:56, 14 February 2009 (UTC)

All of these are very valid points. When I first heard of the collision, I presumed the satellites must have been in the same orbit, with a slight separation of distance; and I assumed that the relative velocity must have been a "slow drift" on the order of meters per second that never got noticed until the two collided. However, this diagram seems to show that the two orbits were quite different ("so they cross paths at a 12 degree angle" of orbital inclination). (The map doesn't look like 12 degrees to me, but I'm not so sure the math was done right). As you say, how could this conflict of orbits have been overlooked when deciding the orbit for the launch planning for the Iridium satellite? Nimur (talk) 04:37, 14 February 2009 (UTC)

The orbits of spacecraft are affected by a multitude of factors which are very difficult to model. The satellites aren't traveling in perfect circles, the orbits change due to the effect of maneuvers, solar radiation pressure, atmospheric drag, effects of a non-spherical earth, third body effects from the moon and sun, etc. This means that orbits cannot be predicted with a high level of accuracy for long periods of time, and certainly not 12 years. Simply put, the two orbits didn't intersect when Iridium 33 was launched (in 1997), and it's likely no orbit could be chosen such that it doesn't intersect with some known object. Orbits are chosen to meet a large number of requirements, and like everything in engineering there is a trade involved. An orbit with very low risk of collision could be chosen at the expense of other requirements, or a higher risk orbit could be used and other requirements met.

It is difficult to predict when a conjunction will occur, and even then it is still probabilistic (a 1 in 25 chance of collision, for example). According to Space Debris, there are around 13,000 cataloged objects in orbit, and collision with almost any of them would be at high relative velocity, and thus catastrophic. To foresee any possible collision, conjunction analysis must be performed for every object which passes through the same altitude as Iridium 33 (or any other object you're interested in protecting), and there are probably thousands in this subset. Since the orbit of any object cannot be reliably predicted for a long period of time, this analysis has to be performed often, which is computationally intensive. When you run the analysis, all you get is probability; it isn't yes or no.

Suppose there is a conjunction with some probability of collision (1 in 25, for example). Do you maneuver to avoid the debris? A maneuver has costs, both in consumables (fuel) and potentially downtime for the satellite (a maneuver might require pointing antennas away from their targets, or some other interruption to service). The line has to be drawn somewhere, and perhaps they chose wrong.

Predicting events like this isn't cut and dried. It is a tradeoff between the risk and the cost of mitigating that risk. Perhaps Iridium didn't find it worthwhile to go through all of this, and mitigated the risk in other ways (on-orbit spare satellites). Perhaps their analysis was insufficient, or perhaps they chose to take their chances and the dice came up snake eyes.

Of course there was little Russian Space Forces could have done since Kosmos-2251 was not functioning at the time. A spacecraft can stop functioning for many reasons, either predictably or unpredictably. Thus it is not always possible to deorbit a non-functioning satellite since it may stop working without warning. To foresee a collision is difficult, as illustrated above, and it's unlikely they would undergo all of the required analysis for a non-functioning spacecraft.

As for the original poster's question, here is a picture showing the orbits of the two spacecraft. Unfortunately I can't find a good source on the relative velocity. My back-of-the-envelope number is about 10,600 m/s, or about 24,000 mph. To arrive at this I assumed two circular orbits at 776 km altitude, which gives an orbital velocity of about 7,500 m/s. The picture shows approximately 90 degrees between the two velocity vectors, making the relative velocity around 10,600 m/s. anonymous6494 07:08, 14 February 2009 (UTC)

Wow - at those speeds, the odds of a collision with 90 degree orbital inclination is astoundingly small. The circumpherence of those orbits is around 40 million meters - if the spacecraft are (say) 10 meters long - then the odds of them colliding - even if their orbits do intersect is about 8 million to one against per orbit. At 8,000 m/s orbital speeds - each orbit takes a couple of hours - so you'd expect a collision like this about once every 400 to 500 years - even if they were both at the exact same altitude! SteveBaker (talk) 23:56, 14 February 2009 (UTC)

Well, you might expect a collision between these two specific spacecraft to take place after 400-500 years. But a collision between any pair of satellites would have been reported on the news, and if we take 6000 as the number of satellites orbiting Earth, the number of pairs would be 5999+5998+...+1=18 million. Obviously it is much more likely than not for two randomly-picked satellites to have orbits that never intersect, but when the number of chances for failure is in the millions, one would expect something to happen pretty often. --Bowlhover (talk) 04:04, 15 February 2009 (UTC)

It would happen pretty often if measures weren't taken to avoid it. I'm not sure how often collision avoidance manoeuvres are made, but I know they certainly happen. --Tango (talk) 14:57, 15 February 2009 (UTC)

As I suggested above, there could be an international convention that any country or group launching a satellite is liable for any collisions it causes with preexisting and still functioning satellites. A defunct satellite could be seized and deorbitted by a robotic retrieval satellite, at the expense of the party launching the dud, to avoid the proliferation of space junk. So it is not correct that "There is little Russian Space Forces could have done." The U.S has discussed robotic deorbitting of the Hubble Space Telescope, for instance. Edison (talk) 14:47, 15 February 2009 (UTC)

Such a deorbitting mission would be very expensive and would take significant time to plan. It seems that these satellites were in polar orbits - it would be next to impossible to arrange polar orbiting satellites in such a way that their orbits never intersected any other satellite. Better tracking of satellites seems to be the answer - the commercial satellite was operational and should have been able to avoid the collision if it had been predicted. At those speeds a tiny course correction just a hour or so before the collision would probably be enough. --Tango (talk) 14:57, 15 February 2009 (UTC)

Have scientists tried mixing every combination of chemicals, elements, etc. together?

Or do they work this out mathematically, because of the obvious dangers? Maybe this sounds impractical. I just figured that most scientists felt they had a duty to uncover and report every secret that nature has tucked away in it's emergent property quantum realm. And to find out what blows up and shit.TinyTonyyy (talk) 22:11, 13 February 2009 (UTC)

I just love how the question ends with "..and shit.". -Pete5x5 (talk) 00:42, 15 February 2009 (UTC)

No to both questions. First off, over 40 million CAS registry numbers have been assigned to known compounds, so combining any two all possible pairs (without even considering such variables as temperature and pressure) would be an daunting task. And I'm fairly certain that modeling reactions computationally is quite difficult (otherwise drug companies would have a much easier job). Clarityfiend (talk) 23:05, 13 February 2009 (UTC)

There is often more to producing compounds than just mixing chemicals. There are certainly new compounds being discovered all the time (check out a Chemistry journal sometime), so they can't have got them all yet! --Tango (talk) 23:17, 13 February 2009 (UTC)

Two more things to consider why it's an emphatic no. Even things that have been combined before sometimes create different compounds under different conditions. Think of temperature, distribution, pressure, agitation and the like. Even computer modeling doesn't help getting things down to size. Folding@home uses huge amounts of computer resources donated from all over the world and they aren't even combining anything. They are modeling at what proteins look like when they are folded in different ways. Depending on what's sticking out where they behave quite differently. 76.97.245.5 (talk) 00:24, 14 February 2009 (UTC)

Imagine if you merely tried that with just a chemistry set containing 32 chemicals. How many mixtures would be required, ignoring order (with 1 to 32 components)? http://en.wikipedia.org/wiki/File:1940s_Gilbert_chemistry_set_04.jpgEdison (talk) 00:43, 14 February 2009 (UTC)

Like 32 with one chemical, 601,080,390 with 16 chemicals, etc. Edison (talk) 02:04, 14 February 2009 (UTC)

In chemistry, atoms of elements combine to form moleculess. Depending on the type anbd position of th ebonds between the atoms, the same bunch of atoms can create completely differnt molecules ("chemicals") with completely different properties. Furthermore, there is no upper bound on the size of a molecule, so there are infinitely many different "chemicals." For example, there are zillions of different moleculres that are composed exclusively of atoms of carbon and hydrogen, and they have have radically different properties. These include gasses (methane, acetelene) liquids, (pentane, hexane, benzene) and solids (Paraffin.) So there are an infinite number of different molecular combinations of just these two elements. No, we have not yet discovered tehm all. -Arch dude (talk) 02:31, 14 February 2009 (UTC)

For a simple explanation of scale, say you have everyone in the world working to combine every pair in the CAS registry. There's 40 million of them, so that's 800 trillion. There are about 6.5 billion people, so that's over 100,000 pairs per person. If each person lives 70 years, that's about 25,000 days, so you'd have to have everyone in the world mix four chemicals a day for their entire lives. That's just every pair. If you want to mix every combination, that's 2^40 million, or about 10^12 million. For comparison, there's about 10^80 to 10^85 particles in the universe. — DanielLC 19:19, 14 February 2009 (UTC)

That's only scratching the surface though - many chemicals require three ingredients in order to react - or special temperature/pressure/agitation - some require specialized catalysts. Then you get things like polymers and proteins that form bit by bit rather than all at once. Truly, the number of possibilities is beyond measurement. Then you have isomers and isotopes. Isomers are chemicals with the exact same 'ingredients' - but different shapes. Something as simple as a benzene molecule can have several 'foldings' ("chair" and "boat" forms of the benzene ring) - others exist in left and right-handed forms - one of which will be biologically active and the other not. With proteins, this 'folding' is absolutely critical. There could be hundreds, thousands, maybe millions of "different" proteins that have identical formulae but are simply folded up differently and therefore have quite different properties. Then most elements have several stable isotopes (ie larger or fewer numbers of neutrons). These have very similar (but not identical) properties - so you might well find that to try everything, there would be a few odd versions of compounds that have the same formula but are built from unusual combinations of isotopes. So doing chemistry by making some of everything and testing it is a dead end. SteveBaker (talk) 03:08, 15 February 2009 (UTC)

Imagination "like becoming someone else" to some people?

My friend has Asperger's Syndrome, so I think I understand why he said this, but he recently remarked to me that when he tries to put himself in another person's shoes, he literally feels like he becomes that person, in a way. Even if it's someone in the past.

Is this because of the autism spectrum rendering normal imaginative play in children - and hence imagination in adults, I presume - hard if not impossible? So that a person with an ASD must practically feel like they become someone else to "imagine themselves" like that?

I'll note that I looked at the imagination article, and it's a little complex, but it almost seems like it's saying that is possible, since imagination is a created world.

Of course, I'll also grant that I probably shouldn't presume that he's using words in the same way I do, either.209.244.30.221 (talk) 22:12, 13 February 2009 (UTC)

Somehow when I read your post I was immediately reminded of the writings of physicist Richard Feynman. Although certainly not in a field you'd think of in this regard he studied and described his ability to multitask. He compared that to what others described/displayed in that regard. People differ in their ability to e.g. listen and read at the same time. Some can write and speak at the same time. You can do your own experiments and compare your and your friend's results with Feynman's. While some people when reading a book hear the text read to them in their head, others see the words float off the page. So there is already a lot of variation in people not described as having any "syndrom" (or "disorder" :). If I'm not mixing things up I think I read that "Aspies" have a very visual memory. So your friend is probably creating a visual picture of the things he reads about in a book. Another thing usually described is the ability to "focus" excessively. So just the opposite of muuti-tasking. So your friend's brain may just not be able to process the information of the imaginary world and the real world at the same time. Empathy may interest you. I must say though that some of the things on that page rubbed me the wrong way. Our resident expert SteveBaker will probably be able to shed a lot more light on things. 76.97.245.5 (talk) 00:07, 14 February 2009 (UTC)

My understanding is that the underlying cause of Aspergers and Autism (and other things along that spectrum) is most likely to be due to a failure or some kind of inadequacy of the mirror neurons. These neurons are the ones that let normal humans understand how other people are thinking by literally modelling a simplified version of their thought processes in your own head. I have Aspergers - and it seems almost like everyone else has some kind of telepathy that lets them all know what each other are feeling! This seems like magic to me! Kinda like the empathic Deanna Troi on Star Trek.

The response your friend gives seems almost completely opposite to how I feel - which is that I'm simply unable to think about how someone else thinks or feels. I would speculate that perhaps your friend has discovered a way around not having a decent set of mirror neurons with which to model the other person's mental processes - but instead literally has to imagine that he is the other person and thereby use his regular neural capacity to model the other person's mental state. So for as long as he does this, he IS the other person. That's a very strange and interesting thing. If that is indeed what is going on, it would definitely be a neat trick...one that I'd very much like to learn. (Presuming it is learnable...not everything is).

I suppose it's also possible that his diagnosis as an Asperger syndrome victim is incorrect.

SteveBaker (talk) 00:45, 14 February 2009 (UTC)

I'm autistic. I have put myself in people's shoes by pretty much imagining I was them, though I'm perfectly capable of empathy without that. I don't know if it works better, but it presumably varies how well it works with the person, so it's possible that your friend finds that it works much better, and does that a lot. When I read, I imagine what it sounds like, so there's at least one Aspie with auditory memory, though I don't see how that's relevant. Also, I don't have any problem imagining things. In fact, I commonly have a problem of getting lost in my thoughts, and imagining stuff when I should be doing something. — DanielLC 19:08, 14 February 2009 (UTC)

Error measurement question

The manual for the equipment says "Accuracy specifications are given as: ±([% of reading] + [number of least significant digits])". Then it gives, for example for one measurement, "0.5% +/- 1". Does that mean I have to multiply 0.5% by my measurement, then add 1? But where does the number of least significant digit come into the calculation?128.163.224.240 (talk) 22:30, 13 February 2009 (UTC)

That kind of expression is usually found on instruments that have a digital readout and is due to an uncertainty in the last digit which is present no matter what the size of the reading. For instance, consider a frequency counter with a six-digit display reading 173.624 MHz. An error of ±0.5% is ±86,812 Hz. To this must be added the uncertainty of the last digit, which in this case represents kHz (1000 Hz) so a ±1 uncertainty corresponds to ±1000 Hz making the total accuracy limits ±87,812 Hz. We can round this to ±88 kHz since the instrument on its current range is only measuring to a resolution of 1 kHz, making the limits for the measurement 173.536-173.712 MHz. SpinningSpark 23:31, 13 February 2009 (UTC)

Isaac Asimov quote on the fractal nature of discovery

Can anyone point me to the quote of Asimov's in which he talks about how every discovery opens a whole new series of questions - he compares the process to the recursive nature of fractals.

Thanks Adambrowne666 (talk) 22:55, 13 February 2009 (UTC)

I believe that scientific knowledge has fractal properties; that no matter how much we learn; whatever is left, however small it may seem, is just as infinitely complex as the whole was to start with. That, I think, is the secret of the Universe.

- Autobiography I, Asimov: A Memoir (pub. post. 1994) - Azi Like a Fox (talk) 23:51, 13 February 2009 (UTC)

Wonderful. Thank you. Adambrowne666 (talk) 02:45, 14 February 2009 (UTC)

Resolved

-Pete5x5 (talk) 00:46, 15 February 2009 (UTC)

Questions about catnip

1. Is catnip an addictive substance (for cats)?

2. Is it possible for a cat to OD on catnip?

3. What recreational drug, when taken by a person would most closely mimic the psychoactive/physical effects of catnip on cats?

Just curious after watching videos of cats getting high on the stuff on YouTube. Thanks. --84.68.107.30 (talk) 00:27, 14 February 2009 (UTC)

1. catnip is not addictive

2. not by rolling in it or smelling it. If the cat eats too much catnip (some cats like to eat fresh catnip, mine does), it may become ill.

refs for these two answers: [46], [47]

3. hard to say, catnip affects different cats differently. Some get loopy, some get aggressive, some get a little sexual. I'd say marijuana, for its euphoric effect, but I don't know a lot of marijuana users that get hyper or aggressive. There's probably not a really analogous human drug. Alcohol is euphoric, but its effect lasts longer and it's addictive. - Nunh-huh 00:49, 14 February 2009 (UTC)

1 How would you define "addictive" in cats. I have had cats do serious damage to containers or cabinets to get at the stuff.

2 Some cats become over excited and can "conk out" from catnip. Others just get extremely tired in a hurry and wander off for a cat-nap. Reactions vary greatly between different cats. Lots of kittens and some older cats aren't affercted at all. BTW: I've seen several cats get the same reaction from elderberry.

3 Androstadienone and/or Musk probably come closest, although not in intensity. We haven't discovered a pheromone for humans that has that strong an effect (thank goodness). Maybe it's just that cats don't care about indulging. After all they are not the ones who have to go out and earn for the tuna cans. Mrrow. Also see [48] - 76.97.245.5 (talk) 02:26, 14 February 2009 (UTC)

Why do cats need a special definition of addiction? I suppose because of the muddled popular meaning of the word, we should specify that we're talking about physical dependency manifested by withdrawal symptoms or increased drug tolerance, and that catnip doesn't cause either. - Nunh-huh 03:17, 14 February 2009 (UTC)

Well caught I was thinking of the other use for psychological addiction. 76.97.245.5 (talk) 07:32, 14 February 2009 (UTC)

According to the second link above, "It is possible for cats to become immune to its effects if exposed too often". Or could it be the case that the regular dose just isn't enough to cause a high any more? How on earth do you determine if a cat is jonesing or not anyway? --Kurt Shaped Box (talk) 09:03, 14 February 2009 (UTC)

Reading a little about the effects of catnip and the short-lived - but seemingly intense high, it reminds me somewhat of the effect that freebasing crack has on a human... --Kurt Shaped Box (talk) 09:11, 14 February 2009 (UTC)

Neanderthals, Humans and Chimps

I was just reading the artical on the Neanderthal genome project. In the artical, there is reference to the Chimp's DNA being 18.77%98.77% identical to modern human DNA. What is it about the remaining 1.23% of the chimp's DNA that makes it impossible for humans and chimps to interbreed (aside from the ethical objections we may hae)? Could modern humans and neandertha;s inter-breed? —Preceding unsigned comment added by 209.161.215.58 (talk) 04:23, 14 February 2009 (UTC)

I'm not sure it's true that chimps and humans can't interbreed. It's not easy because we have one less chromosome than chimps. Two of the great-ape chromosomes are fused together in humans. So while most of the DNA is identical - the way it's glued together isn't. But that doesn't make it completely impossible. Humanzee explains all of the horrible details. It's widely assumed that humans and Neanderthals would have been able to interbreed. SteveBaker (talk) 04:33, 14 February 2009 (UTC)

The degree of identity between human and chimpanzee genomes is not easy to estimate. Figures like the one to which you refer ("98.77%") are fraught with serious problems, as discussed in many papers including this one [49]. The differences go much deeper. --Scray (talk) 05:03, 14 February 2009 (UTC)

Representing the similarity of genomes in term of percentages is very, very misleading. Yes, we share about 98.4% of our genome with chimps, but we also share about 90% with mice and 50% with bananas[50]. First, as mentioned above, percentages don't take into account structural chromosomal differences (fusions, inversions, and the like) that may exist, making interbreeding difficult or impossible even between otherwise closely related species. Second, there is a great deal more information in a genome than just the genes themselves. One major example would be how the genes themselves are regulated: how strongly they are expressed, in which tissues they are expressed, and when. Complicating things further, altering a single base may result in a major change in how the gene product itself functions. One gene often given credit for providing humans the ability of language is FOXP2, which contains 3633 bases in its coding regions. The human and chimp versions differ by only 3 (0.008%) of those bases. Clearly, when it comes to genetics, a little difference can go a long way. – ClockworkSoul 06:26, 14 February 2009 (UTC)

Despite what SteveBaker said, the question of wheather Humans and Neanderthals could interbreed is still an open one and the lack of evidence that any interbreeding took place may indicate that interbreeding was not possible. The only honest answer is that we don't really know yet. Dauto (talk) 18:42, 14 February 2009 (UTC)

Regardless of whether modern humans and neanderthals had viable offspring, there is no reason to believe they did not have sex. Modern humans have been known to have sex with sheep, cows, donkeys, horses, dogs, geese and chickens. Kinsey found that 8% of men and 3.6% of women reported such sexual relations with animals. It strains credulity that early humans and neanderthals never danced the horizontal bop. Edison (talk) 14:39, 15 February 2009 (UTC)

Scientific name

Does the scientific name Cacops aspidephorus mean "bad-face shield-bearer", or is there a more subtle meaning I may have missed? And, if so, why did Williston call this animal "bad-face"? Thanks a lot to anyone who can help. --83.57.77.67 (talk) 07:41, 14 February 2009 (UTC)

Our article on Dissorophidae (which is the family from which Cacops comes) says that all dissorophidae had armored plates over their spines...which explains "shield bearer"...and it says that Cacops is specifically known for having a "relatively huge head". I'm not sure that "bad-face" applies - but I wonder whether "big-face" might not be a better translation? (I long ago forgot any latin I might ever have been taught). It's also possible that the discoverer found this dissorophidae and found that it fitted in with other species in that family - except that the head didn't fit the pattern of the other species. I suppose it's then possible that the head/face was considered "bad" because of that failure to match the other species in that family. SteveBaker (talk) 02:42, 15 February 2009 (UTC)

Your Latin wouldn't help even if you could remember it Steve, I do believe that is Greek. Aspis=shield. The Latin for shield is scutum. SpinningSpark 15:08, 15 February 2009 (UTC)

Mental illness and "colorful" writing

A few questions ago, SteveBaker wrote "(You can tell it's a crackpot site because it's using LOTS of color/italics/underlining)", and I knew (even before I followed the link) exactly what he meant. I've noticed the phenomenon in web pages, I've noticed similar things in flat-text fora (e.g. Robert E. McElwaine's tendency to RANDOMLY capitalize WORDS...) and my father once told me that the American Institute of Physics used to have a special category for crackpot letters they received written with a variety of different-colored pens. My question is: is this writing quirk associated with any particular mental illness? I'd think it would be a symptom of schizophrenia and/or thought disorder, but I haven't seen it actually listed as such. -- Speaker to Lampposts (talk) 09:12, 14 February 2009 (UTC)

I guess emphasis ("shout when argument is weak") takes all forms but you might be interested in the article about green inkers. Another tic is to pad out a erm, "certain articles" with excessive C-quotes. Julia Rossi (talk) 09:16, 14 February 2009 (UTC)

It seems to be quite common on Usenet for the crackpots to pad out their posts (often several, one after the other, crossposted, saying pretty much the same thing, as is the custom) with weblinks and random cut+pasted excerpts from websites which are seemingly unrelated to the topic of the screed. --Kurt Shaped Box (talk) 09:32, 14 February 2009 (UTC)

The best crackpot site of all time has to be Time Cube. A Quest For Knowledge (talk) 11:19, 14 February 2009 (UTC)

I second that. -Pete5x5 (talk) 01:16, 15 February 2009 (UTC)

Alex Chiu and the 'Anus 100' guy deserve honourable mentions for their incomprehensibility and sheer dogged determination to defend their theories in the face of overwhelming criticism and ridicule. --Kurt Shaped Box (talk) 11:58, 14 February 2009 (UTC)

Immortality devices! LOL. I love it! (Those are sentences that deserve exclamation points.) A Quest For Knowledge (talk) 17:37, 14 February 2009 (UTC)

I remembered the anus guy's name now, FWIW. Hiroyuki Nishigaki. Check out some of his musings/ramblings if you can find them online (his website seems to have gone now). His main theory (from what I could understand of it) combined 100-times-daily anal constriction with various other religious, spiritual, alien, pseudo-scientific or downright crackpot concepts to produce a truly (sometimes literally) incoherent wholeness. IIRC, he was also trying to encourage mentally ill people to stop taking their meds on Usenet - which would've been dangerous, if the guy didn't come across as *more* insane than everyone else there present. --Kurt Shaped Box (talk) 22:21, 14 February 2009 (UTC)

Children also tend to randomly write in multiple colors, so I associate that with "immaturity". There are places where color is used to actually mean something, though, like Bibles which use red text for supposed quotes from Jesus. StuRat (talk) 14:27, 14 February 2009 (UTC)

Ding! Ding! We have our explanation! --Kurt Shaped Box (talk) 22:07, 14 February 2009 (UTC)

And don't forget about exclamation marks ! Every sentence should end in at least one, no matter how dull ! It is now 9:30 AM ! And, when the reader gets used to every sentence ending in an exclamation mark, it's time to escalate to several !!!!!!!!! StuRat (talk) 14:31, 14 February 2009 (UTC)

This will go way over your head as my research into this area is decades past general scientific understanding (let alone that of lay people) but here goes: the reason crackpots write with different colors is because they are approaching science with their right brain hemisphere. It is also the reason they fixate on the intuitive meaning of scientific terms (i.e. the impression the term would make before you ever learn what it means), with a seeming inability to internalize the technical definition. This is a style of thinking -- its more useful in some areas of life and science and less useful in others. That's all I will say, because my research on this subject is so far ahead of science that trying to explain it to you in a Reference Desk response would be hopelessly quixotic. —Preceding unsigned comment added by 82.120.236.246 (talk) 15:22, 14 February 2009 (UTC)

Come on, everyone knows any sentence containing the phrase "far ahead of science" HAS to end with an exclamation mark! --Tango (talk) 15:39, 14 February 2009 (UTC)

Then I would have had to say "the reason crackpots write with different colors is because we are approaching science with..." —Preceding unsigned comment added by 82.120.236.246 (talk) 15:53, 14 February 2009 (UTC)

I don't know why they do this - but it's a dead giveaway when you open a web page that looks like that. As for excessive exclamation marks, it helps to pretend that each "!" is really a "?". I doubt that this is a mental illness per-se - but there is certainly a correlation between crackpot theories and tasteless web sites. However - correlation is not causation. SteveBaker (talk) 19:22, 14 February 2009 (UTC)

I guess that depends on whether you count being a complete idiot as a form of mental illness. I've never been quite sure how you distinguish between "learning difficulties" and "stupidity". In cases where there is a definite cause for the learning difficulties, it's pretty simple, but in other cases I'm not sure there actually is a distinction. --Tango (talk) 20:07, 14 February 2009 (UTC)

Another common 'red flag' for these quacksites seems to be the overuse of mid-90s-web-style animated gifs and stock clipart. Has anyone else ever noticed that? --Kurt Shaped Box (talk) 22:38, 14 February 2009 (UTC)

Pretty much everything about their webpages boils down to them being stuck in the mid-90s (you forget to mention <blink> and <marquee> tags!). I have no idea why... --Tango (talk) 23:25, 14 February 2009 (UTC)

They like <center> tags too. SteveBaker (talk) 23:45, 14 February 2009 (UTC)

The use of several different fonts, bold/italic styles and text sizes within the same paragraph/block of text too. I wonder if they're deliberately trying to give the impression to their readers that they were chewing the keyboard when working on the site? --Kurt Shaped Box (talk) 00:44, 15 February 2009 (UTC)

Another dead giveaway to me for a crackpot letter is its ending. It's usually "Think about it!"

Think about it!. Bunthorne (talk) 21:48, 14 February 2009 (UTC)

Thought-terminating cliché#Non-political examples. Most of these websites will also have a colourful array of fallacies within them (no pun intended). --Mark PEA (talk) 12:29, 15 February 2009 (UTC)

Yes, such as circular logic. The reason that circular logic tells us these sites are run by crackpots is that, as previously established, circular logic tells us these sites are run by crackpots. StuRat (talk) 17:31, 15 February 2009 (UTC)

I guess you are arguing that there is no evidence that the sites are run by crackpots, but the definition of crackpot could be "someone who uses colourful writing and talks crap", which would mean it is not circular logic. Although hasty generalization is still possible. --Mark PEA (talk) 18:28, 15 February 2009 (UTC)

Is there any way to repair a cracked DVD?

I have a dual-layer DVD-Video disc with a full-thickness crack running from the centre, to about 1cm into the data area. Is there any possible way that I could either fix the disc, or even just render it readable for long enough for me to make a copy?

I guess that the answer's going to be 'no' - but hey, it's worth a try if it saves me having to buy the movie again... ;) --Kurt Shaped Box (talk) 13:04, 14 February 2009 (UTC)

If it's full-thickness, then probably not (surface scratches are another matter). Almost certainly not easily (you might be able to pay a specialist company lots of money to get the data off, like you can with broken hard drives, but I doubt that's worth it). You might be able to get the DVD replaced for free (or maybe for a small admin/p&p fee) from the manufacturer, though - if all the DRM and EULA stuff is to be believed, what you bought wasn't the DVD but rather a license to the content that is on the DVD, so it makes absolutely no sense for them to charge you for the content again just to replace the DVD (of course, sense doesn't really come into it!). Try asking at wherever you bought it. --Tango (talk) 13:12, 14 February 2009 (UTC)

I wouldn't count on them replacing it for free. They conveniently either say you are buying the disc or the content on it, whichever way will get them the most money. Can we get free DVDs by turning in old VHS tapes ? I doubt it. StuRat (talk) 14:22, 14 February 2009 (UTC)

DVDs usually contain additional content that wasn't on the VHS version, so almost certainly not. --Tango (talk) 15:45, 14 February 2009 (UTC)

Even if it isn't, the idea that the content and the medium are totally separable is certainly not part of the EULAs. --98.217.14.211 (talk) 00:39, 15 February 2009 (UTC)

As for the original Q, I'd guess that there is some way you could "fix" the DVD. By this I mean glue it together so it won't fall apart when played. However, the data in the vicinity of the crack will still be lost. This is merely annoying for music and video, but will make any program on the disk completely unusable. StuRat (talk) 14:22, 14 February 2009 (UTC)

It may be worth writing to the publisher. I did this once with a similarly damaged CD and they replaced it for the cost of postage after I had sent them the damaged original. -- SGBailey (talk) 18:41, 14 February 2009 (UTC)

There's some stuff you can buy to repair plastic eyeglass lenses that might work to repair the plastic part. The data as Stu said is another matter. Try opticians for the chemical (comes in a very small tube.) I came across it once and stocked up. I haven't seen it since. 76.97.245.5 (talk) 22:36, 14 February 2009 (UTC)

Have you tried playing it? DVDs have a lot of error correction and it may still be playable. In that case (if you can break the copy protection, which is possible) you could copy it to a new disc. --Chetvorno^TALK 07:49, 15 February 2009 (UTC)

Let me say right off that there is no way you'll be able to 'repair' the disk. Forget it - it's not gonna happen. Even if it did work, the extra weight of the glue on one side and not the other would unbalance the drive and either prevent it from playing or damage the bearings in the DVD drive. However, I would expect the error correction systems to be able to recover data from the DVD so it should play OK providing that's the only damage. If it also has some fine scratches, dust or fingerprints then there may just be too many errors for it to recover from. But there is another problem. A crack that goes all the way through the disk will have a very good chance of spreading and eventually causing the DVD to shatter while it's spinning. I would STRONGLY advise against playing it in a computer DVD drive because those can spin a lot faster than a Video-only DVD player and if a DVD comes apart at high RPM, it can do some serious damage. (I refer you to a Mythbusters episode where they tried playing various optical disks to make them fly apart). The trouble is that the other advice I'd like to offer would be to suggest 'ripping' the movie off of the DVD and writing it onto a blank disk using your computer...but with the risk of the disk shattering when you do that...I'm beginning to think that this is actually a bad idea. IMHO, you should first contact the company that made the disk and ask for a replacement. I think they'll probably give it to you - although they might want to charge for shipping & handling. SteveBaker (talk) 17:00, 15 February 2009 (UTC)

so cola is TERRIBLE for your teeth. Does swishing with water immediately afterwards help?

I heard cola is terrible, horrible for your teeth. Drinking thru a straw helps, but I wonder: would swishing your mouth thoroughly with clear water immediately afterwards also help any? I am not asking for medical advice! —Preceding unsigned comment added by 82.120.236.246 (talk) 15:09, 14 February 2009 (UTC)

Saying "I am not asking for medical advice" doesn't make it true. This is quite obviously a request for medical advice. Ask a dentist. --Tango (talk) 15:43, 14 February 2009 (UTC)

Yes, actually, it does -- saying, in bold, "I'm not asking for medical advice" means I'm not asking for medical advice. —Preceding unsigned comment added by 82.120.236.246 (talk) 15:53, 14 February 2009 (UTC)

No, it doesn't. You're asking for something which requires expert medical understanding and could easily lead you to behaviors which are not safe. Appending a contradictory statement to the end of it doesn't change that fact. It just makes your bolded statement false. --98.217.14.211 (talk) 00:42, 15 February 2009 (UTC)

Cola is no worse for your teeth than other soft drinks. For healthy teeth it's best to avoid drinks with added sugar. Rinsing your mouth thoroughly might remove some of the sugar.--Shantavira|^{feed me} 16:03, 14 February 2009 (UTC)

The carbonic acid, citric acid and phosphoric acid isn't good for them. There are plenty of soft drinks that aren't anywhere near as acidic. There are also plenty of soft drinks that aren't high in sugar. --Tango (talk) 16:30, 14 February 2009 (UTC)

Then what are you doing? --Tango (talk) 16:26, 14 February 2009 (UTC)

This possibly? SpinningSpark 16:33, 14 February 2009 (UTC)

Verifying that a CO detector works

Is there an easy and safe way to verify the correct functioning of a CO detector? --173.49.17.152 (talk) 19:33, 14 February 2009 (UTC)

Does it have a "test" button? That will verify that the batteries aren't flat. As for verifying that it actually detects CO, I'm not sure... you could try holding it up to your car's exhaust pipe while it's running (outside, otherwise you'll end up giving yourself CO poisoning while testing your CO detector, and that would just be silly!). But really, I think if you have reason to doubt your CO detector is working, you should just get a new one. It's not worth the risk. --Tango (talk) 20:05, 14 February 2009 (UTC)

That, of course, would be the easy answer. From what I understand, CO detectors have a finite lifetime, but some fail earlier than others. Although early replacement would be a (somewhat expensive) solution, it would still be nice to be able to verify that a CO detector is actually working even when its age suggests that it should. Like you pointed out, the test button merely tells you that the battery is not dead. With a smoke detector, you can use a smoke pencil to verify that it does detect smoke. I was hoping that there's a similar solution for CO detectors. --173.49.17.152 (talk) 20:23, 14 February 2009 (UTC)

Some CO detectors have self-diagnostic modes which give a more detailed test than simply "is the battery ok". For example, some have a test involving lighting a cigarette near to it, while in the test mode. The instructions supplied with the detector will have further information. DuncanHill (talk) 20:34, 14 February 2009 (UTC)

If you have cigarettes around, you probably don't need the detector to know you're getting too much CO. What are normal people supposed to do? Run out and buy cigarettes just to test the detector? --Trovatore (talk) 21:35, 14 February 2009 (UTC)

Normal people already have cigarettes available, we just prefer not to waste them testing electronic equipment! DuncanHill (talk) 21:38, 14 February 2009 (UTC)

Ah, read the manual... Can we pretend that my first recommendation? --Tango (talk) 20:36, 14 February 2009 (UTC)

(ec) There may well be, I don't really know how CO detectors work (although, knowing me, I will now compulsively find out!). I do, however, know how nasty CO poisoning is, which I why in the absence of a definite answer to a contrary my advice is to risk wasting money rather than risk wasting your haemoglobin. --Tango (talk) 20:36, 14 February 2009 (UTC)

I could be wrong but I'm doubtful that any manufacturer (at least in any country with strong and enforced consumer protections) would give device intended to be life-saving a lifespan that's likely to result in a substanial number of devices 'expiring' before then. In other words, if the manufacturer says you should replace the device in 6 years (random guess) only a tiny number of devices are likely to fail before then (and it not be detected by the self diagnostics). So it's not so much replacing the device early as on time Nil Einne (talk) 05:08, 15 February 2009 (UTC)

Try a smoldering incense stick. This will work for smoke detectors too. If it sounds the alarm, OK. If it doesn't, the stick is either not emitting enough CO or the detector is not working. A smoldering incense stick is also useful for revealing drafts, and does not leave the unpleasant smell of a cigarette. Check ebay for sources of incense. – GlowWorm. —Preceding unsigned comment added by 98.17.32.201 (talk) 23:46, 14 February 2009 (UTC)

Mysterious Dead

Recently someone, who in turn got it from anonymous source, sent me a photograph of a dead animal that seems to be something between a bear and a dog. I could not find any refernece on Wiki. I have verified that actually the picture comes from a blog, but that damned blog has only pic and no explanation. Since I do not have the copyright and don't know who the author is, I cannot put it on Wiki. Instead I am putting it on my website : http://www.khurmi.com/sqyy.jpg. Courageous Wikipedias are urged to have a look at it and tell me what the hell it is. Please reply on my talk page.  Jon Ascton  (talk) 21:45, 14 February 2009 (UTC)

We'll reply here, we always do. --Tango (talk) 21:47, 14 February 2009 (UTC)

It's not a great picture, most of the nose is covered by grass, which doesn't help. It looks like a dog to me, though (probably an unusual crossbreed). --Tango (talk) 21:48, 14 February 2009 (UTC)

Looks like a black Chow-Chow mix. Compare [51]. Poor dog. 76.97.245.5 (talk) 22:25, 14 February 2009 (UTC)

(For some reason, the OP deleted this question and all of it's answers. Please don't do that.) SteveBaker (talk) 23:40, 14 February 2009 (UTC)

Whatever it is, it's been photoshopped pretty significantly. If you zoom in on the thin blades of grass over the animal's head, you can see that quite clearly. All bets are off. It could be anything - or nothing. SteveBaker (talk) 23:33, 14 February 2009 (UTC)

I don't see it... what am I looking for? --Tango (talk) 00:07, 15 February 2009 (UTC)

I don't see anything like canine teeth. And it's blue?? Cuddlyable3 (talk) 00:12, 15 February 2009 (UTC)

It's not just that - but look at the 'specular' highlight on the animals' black nose...the reflection is blue...it should be white. If you blow up the region around the grass blades, there are whole pixels of green and whole pixels of blue - and other than the color bloom that's caused by JPEG encoding, there is no soft average of grass-color and fur-color. There is no camera data in the EXIF data. It's eyes are blue too...it's a crappy photoshop job - it just screams it. SteveBaker (talk) 01:49, 15 February 2009 (UTC)

That's not a crappy Photoshop job. This is a crappy Photoshop job. The image under discussion is either a pretty good Photoshop job or real. The blue tint is presumably due to poor color balance in the camera, which has no analogue in computer graphics—and anyway, the light on the nose looks more diffuse than specular to me. The image was clearly cropped and probably resized (I don't think any digital camera takes photos in that aspect ratio), which would explain the lack of EXIF data. The green-blue boundaries don't look suspicious to me. Read the story of the Lumber Car as a cautionary tale. It looks implausible on the face of it, so people pore over the image for evidence of Photoshopping, and they find it, because most images of this (rather poor) quality have features that can be ambiguously interpreted as Photoshopped. That way lies conspiracy-theorist madness. -- BenRG (talk) 15:23, 15 February 2009 (UTC)

I've seen the 'lumber car' pictures before - they didn't strike me as photoshopped at the time - and it's good to hear that they were genuine. In order to discover whether an image might have been tampered with, you have to look at the subtle signs of color, lighting, shadows, etc. Those are all as they should be in the lumber car picture - but they most certainly AREN'T right in this one. SteveBaker (talk) 16:48, 15 February 2009 (UTC)

Diffuse light takes on the color of the object (which in the case of the nose - is black) and reflects more or less equally in all directions - specular light is constrained to a region where the angle of the incident light is roughly the same as the angle of the camera to the object. In this case, the parts of the nose that are angled away from us are black - so there is little if any diffuse reflection going on - the bright spot is therefore a SPECULAR glint. Specular reflections take on the color of the light source (which would have to be blue in order to make a blue splotch on a black object). The only way a 'shiney' spot on a black object could be blue would be if the photograph was taken in blue light - or if the camera was not registering red and green very well. However, the grass is green and there are other white things in the scene - ergo neither the light nor the camera was favoring green. It WAS tampered with. If there was excessive blue balance in the camera then you'd wouldn't have such bright green grass. I have some considerable experience with computer graphics, lighting and coloring and I can assure you that image was messed around with by someone who didn't know how to do it well. As for conspiracy theories - which is more likely - that someone (inexpertly) messed with the photo - or that there really are blue dog-bear hybrids running around loose unknown to modern science? SteveBaker (talk) 16:43, 15 February 2009 (UTC)

NOW you're really extrapolating, Steve. The only evidence we have is of blue dog-bear hybrids lying on the ground looking dead. Did I miss the photo or other evidence of one running around? You really should stick to the 'facts'. ;-) --Scray (talk) 17:23, 15 February 2009 (UTC)

How fair is a coin?

How fair is a physical coin? I mean, what by percentage does it favor heads or tails, when flipped in the standard way -- it must by SOME amount, since there must be more material on one side than the other. Also, how many standard deviations away from the average would this favor be? Thanks! —Preceding unsigned comment added by 82.120.236.246 (talk) 21:57, 14 February 2009 (UTC)

Slightly different, I know, but careful analysis suggests that a coin will land the same way it started about 51 percent of the time. In reality, this probably favours heads. The weighting issue - which would differ based on the coin used - pales in comparison to human jitteriness (which is what actually introduces the randomness), I'm afraid. - Jarry1250 ^{(t, c)} 22:18, 14 February 2009 (UTC)

Is there really a standard way to flip a coin? It can't be completely standardised or the result would be predictable. Cuddlyable3 (talk) 00:10, 15 February 2009 (UTC)

The coin will always favour the side which it was flipped from. This is because the spin is unbiased only if the coin rotates about an axis that is orthogonal to its normal. Otherwise it favours the face starting on top. There are a lot of recent studies that suggest this bias is indeed close to 1%. (Too lazy to find any links). —Preceding unsigned comment added by 99.255.228.5 (talk) 00:44, 15 February 2009 (UTC)

Assuming that each coin flip has the same bias and is independent of all other coin flips, you can correct the bias using some unbiasing procedure. Here's one way to do that:

1. Starting with the head side up, flip the coin once.
2. Starting with the head side up (again), flip the coin a second time.
3. If the two coin flips come out different, take the result of the first coin flip.
4. Otherwise, start over.

This will work so long as the coin flips don't come out the same way 100% of the time. --173.49.17.152 (talk) 17:18, 15 February 2009 (UTC)

Bias reduces the probability of getting two different results in succession from the ideal 50%. However the bias that affects every individual flip still affects the coin (first) that you choose. A way of reducing the bias is to toss a second coin to choose whether to take the first or second flip of the first coin. Cuddlyable3 (talk) 18:34, 15 February 2009 (UTC)

Energy vs mass

Does something have energy because it has mass? Or does something have mass because it has energy? Or do the two exist because of some higher attribute?128.163.224.222 (talk) 23:02, 14 February 2009 (UTC)

Both, the two are really just different manifestations of the same thing. Einstein's famous equation, E=mc², tells us how they are related. The c² part is really just there to convert the units - from kilograms to joules or whatever (just like you have to multiply by 2.54 to convert inches to centimetres, you have to multiply by 3x10⁸ to convert kilograms to joules). Essentially, energy and mass are equal. We often talk of rest mass, which is the mass something has when it doesn't have any other energy (what gives things their rest mass is something of an open question, see Higgs mechanism if you want the technical details of the most popular theory). When you move an object you give it kinetic energy, that results in it having a greater mass (we call it relativistic mass). It's that greater mass that makes it impossible to accelerate something to the speed of light - as it gets faster and faster and gets heavier and heavier and takes more and more energy to accelerate it, it would take an infinite amount of energy to get it all the way to the speed of light. Does that help at all? --Tango (talk) 23:22, 14 February 2009 (UTC)

In ordinary experience mass and energy are independent properties that co-exist. Only extreme cases such as nuclear fusion or fission, such as in the sun or A- and H-bombs, demonstrate that one can convert into the other. Whether there is some higher attribute than these in the universe sounds like a religous question. Cuddlyable3 (talk) 00:06, 15 February 2009 (UTC)

It's a perfectly reasonable scientific question - if two things are related, it's sensible to ask if perhaps they have a common cause. --Tango (talk) 00:16, 15 February 2009 (UTC)

Electric fields and magnetic fields can be converted into one another—because they are basic components of a single electromagnetic force. Asking the underlying connections between related quantities is one of the fundamental physics questions, nothing to do with religion. --98.217.14.211 (talk) 04:02, 15 February 2009 (UTC)

The illustration I like is that a hot cup of coffee is slightly heavier than it is when it has cooled off. --Chetvorno^TALK 07:57, 15 February 2009 (UTC)

Just because we can write down an equation which relates two quantities by nothing but a constant of nature does not mean that these two quantities are the same. In fact, energy and mass are two different things, in relativistic as in Newtonian physics. That's relatively easy to see mathematically (energy is the time-component of a particle's four-momentum, mass is the four-momentum's invariant length, hence the full connection is $E^{2}-p^{2}=m^{2}$, where I have set c=1), and somewhat harder to describe in words. I like to put it as follows: Energy (along with its companion, momentum p) describes how a particle is moving. This should make it obvious that the energy of a particle depends on the reference frame in which it is measured, as is the case for kinetic energy in Newtonian mechanics. The mass of a particle puts constraints on the motion that is possible for that particle (because the relation $E^{2}-p^{2}=m^{2}$ has to be fulfilled). Famously, particles with zero mass always travel at the speed of light, particles with mass have to travel at less than the speed of light. $E=mc^{2}$ is a special case of the relation quoted above, and is valid in the particle's rest frame. It says that even when a particle is at rest, we have to attribute an energy (numerically equal to its mass, multiplied by c², although that's just a matter of the units we use) to it, something that is not the case in Newtonian mechanics. --Wrongfilter (talk) 12:42, 15 February 2009 (UTC)

That's rest mass, of course. The now unfashionable relativistic mass is just the same thing as energy. Algebraist 13:58, 15 February 2009 (UTC)

Indeed. It's unfashionable because it isn't actually very useful when doing calculations, and whatever. It is, however, quite a good way of thinking about it when you are trying to get your head around why the speed of light takes infinite energy, and related concepts - that's why I answered the OP's question in terms of it. --Tango (talk) 15:01, 15 February 2009 (UTC)

Runaway propeller

I am listening to A Case for Dr Morelle on the BBC iPlayer, and an aeroplane in the story suffers from a "runaway propeller". What might this be? DuncanHill (talk) 23:52, 14 February 2009 (UTC)

If the governor associated with a constant-speed propeller fails, the propeller blades may feather to an extremely fine pitch. This will sharply reduce the load on the engine, and – unless corrective action is taken immediately – the engine may redline. Damage can occur to the overspeed prop itself, to the engine, or both. (A rough analogy from the driving world — imagine driving at highway speed and suddenly shifting down into first gear.) TenOfAllTrades(talk) 04:05, 15 February 2009 (UTC)

If the engine speed is constant and the pitch is automatically controlled, what is left for the pilot to control? How does he adjust the thrust? —Bromskloss (talk) 12:26, 15 February 2009 (UTC)

The name 'constant-speed prop' is a tad misleading. It shouldn't be read to mean that the prop maintains a constant speed at all times during the flight; as you've quite correctly surmised, that would leave no obvious way to control thrust. Instead, the pilot has a second control in the cockpit (usually adjacent to the throttle) which allows for selection of the target engine speed (RPM). On takeoff and climb, the pilot will choose a high speed, corresponding to finer prop pitch and greater power. During level flight, the pilot will move to a lower speed, corresponding to greater prop pitch, lower engine speed, and better fuel economy.

Here are a couple of links that go into a bit more detail: [52], [53]. TenOfAllTrades(talk) 14:16, 15 February 2009 (UTC)

• Excellent, many thanks! DuncanHill (talk) 15:46, 15 February 2009 (UTC)

Can we create giant insects like those that lived during the Carboniferous period?

During the Carboniferous period, insects could grow much larger than today due to the high oxygen levels. So, why can't we breed insects under high oxygen conditions and select for size, or use genetic manipulation techniques to create large insects? Count Iblis (talk) 23:57, 14 February 2009 (UTC)

We probably could if we really wanted to. I'm not sure selective breeding would get us anywhere near those sizes in a reasonable amount of time, but genetic engineering might be able to. --Tango (talk) 00:04, 15 February 2009 (UTC)

The American cockroach can grow to amazing size. (Not quite big enough to saddle, despite the common saying.) Which leads to the question what you'd do with your giant bug and what would it feed on? There may be some use in the entertainment industry (Godzilla vs Ibis bug). Our next problem, though, is going to feed the steadily growing human population, not entertaining them. If your bugs were edible, could be fed on something that would not have a negative net food value it might be worth the resources expended to create and maintain it. All that would be left to do would be to train humans not to get the creeps when they find out what's in that hot dog. But then there are cultures who eat bugs.76.97.245.5 (talk) 02:24, 15 February 2009 (UTC)

There is a perfectly extant and very large terrestrial arthropod, the Coconut crab. It's not an insect, and its respiratory system is quite different from that of the modern insects; but it is still an arthropod (so same basic body arrangement, exoskeleton, open circulatory system, etc...). Does it fit your bill? Or are you rather asking about "breeding back" Meganeura and such? --Dr Dima (talk) 03:54, 15 February 2009 (UTC)

Probably a major reason those insects were able to grow bigger was because there was more oxygen in the air. Which is good for the rest if us as you'll have to keep them in a special enclosure. I've seen the effects when such creatures are released.:) Dmcq (talk) 12:25, 15 February 2009 (UTC)

Yes, I think that is understood to be the primary reason they were bigger. The OP said as much. --Tango (talk) 15:03, 15 February 2009 (UTC)

We still have a few moster flying insects around: Attacus atlas the Atlas Moth for instance, and Ornithoptera alexandrae the Queen Alexandra's Birdwing butterfly. Although neither of them comes anywhere near Meganeura's 30 inch wingspan. SpinningSpark 16:13, 15 February 2009 (UTC)

How do I genetically engineer the world's best sports team?

I was thinking thru cloning. Like chip some skin off our top baseball and football players and thier offspring's genetic code would be the same, right? So they would have an excellent chance of being athletic in a superior way, I take it? Then in about 20 years,-"And now,- presenting the only 162-0 baseball team in history,-". They would then take the field proudly and win another 27-0 shutout. Is this dream possible?Baseball and and and Popcorn Fanatic (talk) 00:17, 15 February 2009 (UTC)

How do you genetically engineer the world's best sports team? You begin by getting a degree in genetic engineering and hope that by the time cloning techniques are advanced enough to allow such a thing, that it is legal to do so in whatever country you plan on cloning your humans. In addition, you also need to make sure that for whatever sport you plan on having your players compete in, that cloned humans aren't banned similar to doping. There's also the question of whether your human clones will actually want to play for you and not other teams. Finally, if you plan on having your players compete in a professional league, you may find it useful to buy a franchise. But be forewarned that such franchises are cost-prohibitive. The Chicago Cubs, for example, are currently being sold for $900 million. A Quest For Knowledge (talk) 01:18, 15 February 2009 (UTC)

You may also wish to consider what makes you enjoy watching your team win. Is it the elegance of each batter's swing and the movements of the catchers (sort of like ballet?) or is it the uncertainty of the outcome of the game? A majority of spectators would abandon the game if your team so far outperforms other teams that the outcome is a given. So your franchise would go broke and your perfect players would have to go work in jobs they weren't engineered for. 76.97.245.5 (talk) 02:04, 15 February 2009 (UTC)

Your clone breeding project comprises a violation of Equal opportunity that not even eugenicists contemplate, and which would raise issues of medical ethics and legality in athleticsCuddlyable3 (talk) 18:17, 15 February 2009 (UTC)

speeding up human gestitation

is there any way to speed up the 9 months? how about in non-humans? —Preceding unsigned comment added by 82.120.236.246 (talk) 00:52, 15 February 2009 (UTC)

It seems very unlikely. Any effort to mess around with the cell division rates would likely screw up the development in one way or another. Perhaps you could do it in VERY primitive organisms - but not in 'higher animals'. SteveBaker (talk) 01:44, 15 February 2009 (UTC)

That's only if you want the newborn to be normally developed, of course. It's easy enough to induce birth early if you don't mind an underdeveloped baby. Algebraist 02:53, 15 February 2009 (UTC)

You could always have nine women work on one baby, they should be able to get it done in about a month.--OMCV (talk) 02:56, 15 February 2009 (UTC)

You, sir, should work in management. You would go far. -- Captain Disdain (talk) 09:06, 15 February 2009 (UTC)

As far as non-humans go, in viviparous reptiles it is possible to reduce the gestation length by increasing the ambient temperature, up to some point. For mammals, esp. placental mammals - I doubt it. --Dr Dima (talk) 04:18, 15 February 2009 (UTC)

Travel in a spaceship and come back. You will notice time dilation. But don't go too far or too fast or you'll miss a birthday or few.Cuddlyable3 (talk) 17:51, 15 February 2009 (UTC)

Most non-humans already gestate in fewer or more than 9 months, presumably for their own good reasons. Cuddlyable3 (talk) 17:54, 15 February 2009 (UTC)

Yellow Sodium Light

Hello. Why is yellow sodium light the reference point in determining refractive indices? Thanks in advance. --Mayfare (talk) 05:13, 15 February 2009 (UTC)

Until an expert comes along, all you'll have is an educated guess. Yellow is kinda in the middle of the optical spectrum, the sodium output is very bright and unambiguous, and a yellow sodium light emitter should be readily available to any researcher (if nothing else, salt sprinkled in a Bunsen burner flame). Bunthorne (talk) 05:46, 15 February 2009 (UTC)

Sodium has a bit of info on the history. Also see Fraunhofer lines 76.97.245.5 (talk) 06:04, 15 February 2009 (UTC)

(EC) note by unambigious a key point may be it's fairly monochromatic Nil Einne (talk) 06:09, 15 February 2009 (UTC)

Indeed, the key point is that it emits light at one very specific and precisely known frequency. --Tango (talk) 12:39, 15 February 2009 (UTC)

Think about white light (eg sunlight). If you shine white light through a narrow slit and into a triangular slab of glass (a 'prism') it spreads out into a broad rainbow-like spectrum. It's hopeless to try to measure the angle the light was bent by because each of the colours got bent by a different amount. When you measure refractive indices, you are measuring that angle - and you get a different answer for different frequencies of light - so if you want to express it as a single number, you need a very pure light source. Sodium emits an almost pure yellow light - there are actually two frequencies but they are very close together. When you shine sodium light through a slit and into a prism, it doesn't split up - you get just two bright yellow lines (which are very close together) instead of a rainbow. It's easy then to measure the angle between the incoming and outgoing light and calculate a simple refractive index. If you used white light, you'd have to guesstimate (say) the middle of the fuzzy red/orange/yellow/green area and that would produce hopelessly inaccurate results. SteveBaker (talk) 15:25, 15 February 2009 (UTC)

For those who are interested, our article on sodium vapor lamps has a pretty picture of the low-pressure sodium emission spectrum. Check out the article or jump directly to the image: File:Low-pressure sodium lamp 700-350nm.jpg. (The image has been somewhat overexposed to make the other emission lines visible; this also causes the sodium D line to 'bloom' out a bit.) TenOfAllTrades(talk) 16:59, 15 February 2009 (UTC)

science/geology---tides!!!

If moon's attraction causes tides during nighttime,,, but why they not occur during daytime,, even if moon is present at that time? —Preceding unsigned comment added by Nilesh raj (talk • contribs) 06:39, 15 February 2009 (UTC)

Who says they don't? See the graph or the daytime pictures of the Bay of Fundy in the Tide article. Also, surfers don't go out only at night. Clarityfiend (talk) 07:35, 15 February 2009 (UTC)

There are definitely tides during the day. You usually get one high tide about every 12 hours (it's not exactly 12 hours since the Moon is orbiting as well as the Earth rotating - that's what causes the tides to be at different times each day). --Tango (talk) 15:11, 15 February 2009 (UTC)

Oh cool! I can use the word! Can I say 'syzygy'? Can I please? ... Oh good - thanks!

The tide is at it's highest when there is a syzygy - which is when the sun, moon and earth are all in a straight line. That happens during the day and during the night when there is either a total solar eclipse or a total lunar eclipse.

SteveBaker (talk) 18:40, 15 February 2009 (UTC)

ENGINEER'S HELP NEEDED

HI FRIENDS

I AM RESIDING ON GROUND FLOOR OF A 3 STOREY APARTMENT.

THE PERSON RESIDING ON 1ST FLOOR ABOVE MY HOUSE HAS GOT HIS BATHROOM LEAKING IN MY HOUSE.

I TRIED HARD TO PURSUE HIM BUT HE IS NOT WILLING TO MAKE REPAIRS & ALSO IS NOT ALLOWING ME TO DO SO.

WHAT SHGOULD I DO?

I HAVE HEARD OF CHEMICALS(FOSROC HYDROPROOF)WHICH CAN HELP IN THIS BUT DONT KNOW MUCH.

ALL THAT CAN I DO IS TO MAKE REPAIRS FROM MY HOUSE ONLY, THAT IS, FROM THE BOTTOM ONLY.

IS THIS POSSIBLE?

PLEASE SUGGEST. —Preceding unsigned comment added by Saurabh85 (talk • contribs) 10:31, 15 February 2009 (UTC)

PS: On the user page of user:Milkbrath the OP mentions that he ad his / she and her neighbour are owners the apartments. --Cookatoo.ergo.ZooM (talk) 16:04, 15 February 2009 (UTC)

First of all, I suggest you turn off your caps lock key.

Secondly, to begin with, I suggest you contact the owner (or owners) of the building, or the building's manager, or some comparable party. Water damage can get very expensive if the problem isn't addressed, and it's likely to affect a lot of people other than just the people who live in the apartments in question. You don't mention whether you own the apartment or are renting; if you're renting, contact your landlord. The Wikipedia Ref Desk is probably not a good place to get help with this; you really should notify the building's owner or owner's.

Thirdly, I very much doubt that any chemical could fix this problem. I guess it might keep the water from your apartment, but it's not going to make the water go away: it's still going to be up there, leaking and doing damage. It will rot wood, rust steel, cause molds to grow, etc. You really need to move on this now; the longer you leave this, the more damage there will be. The leak needs to be fixed.

Fourthly, your neighbor is not only an asshole, but -- depending on where you leave -- probably also in a bad position legally; if he's aware of the problem but refuses to do anything about it, he's probably going to end up with a pretty hefty bill. We don't do legal advice, but let me put it this way: it's probably not a good idea for you to be aware of it and not report it to anyone, either. -- Captain Disdain (talk) 11:32, 15 February 2009 (UTC)

You state that you both are the owners of your respective apartments. As such, there must be an occasional meeting of owners to agree on communal matters where this problem should be discussed. Alternatively, as CD points out, there must be an appointed manager who looks after groundkeeping / general repairs / lift maintenance / etc.

You may also consider to call a plumber to determine the cause of the problem and to have an expert witness at hand. If nothing else helps, take a few photos of the damp patches / dripping water / mould / whatever and contact a lawyer. Finally, you may consider the benefits of having an apartment with an indoor swimming pool. --Cookatoo.ergo.ZooM (talk) 12:04, 15 February 2009 (UTC)

You don't need an engineer's help. You need legal help. Dmcq (talk) 12:06, 15 February 2009 (UTC)

Maybe it'll help you if you do a little experiment to visualize your problem. You'll need 2 or 3 slices of bread. Spread a good layer of butter or margarine on two of them. Turn your faucet to a slow drip and hold the piece of bread without any spread underneath. The bread will get soaked and sooner or later water will drip from the bottom. That's your ceiling now. Next turn one of the buttered slices upside down so that the side with the spread on it faces away from the faucet. Hold that one under the faucet. That's what you'd get if you tried to seal your ceiling from below. Not satisfactory, is it? The only way to solve your problem is to stop the leak or seal the ceiling from the top. (i.e. your neighbor's floor). If there still was a leak in his bathroom (e.g. from a leaky gasket or runoff from a shower curtain) the water would then collect on his floor and he could mop it up. That is the idea behind the products you read about. They are intended to prevent the water from leaking into the ceiling. Once it's in there it will have to go somewhere. If you'd block the ceiling it would just run into your walls into your closets and under your flooring and damage those, too. It's not that we wouldn't want to help you, it's just that sealing your ceiling from the bottom isn't an idea that would work. Don't know where you are, so I can't tell you what's available in your area. You may qualify for free legal assistance from some organization. Check your condo contract and your insurance policy and follow the advice the others have given. OR We have an occasional leak in our basement and are now into our third expert trying to find and remedy the cause. This kind of thing isn't a job for DIY even if you had better skills and knowledge than you seem to have. 76.97.245.5 (talk) 14:07, 15 February 2009 (UTC)

You don't say where you are from - and you don't say whether you and your neighbour own the apartments or are renting them - so it's hard to guess what legal options might be open to you. For sure there is no technical/engineering solution. That water is landing on your ceiling and that's that. If your ceiling is showing damage - and presuming you have insurance on your apartment - then I would make a claim on your insurance for the damage. They will come and investigate - they'll realise that your neighbour is at fault and will make a claim on him. Then there will be action. If you are renting the apartment - then you need to talk to your landlord. Whatever you do - you need to do it soon because your ceiling will collapse...and you'll also be getting mold growing up there which could have serious effects on your health. You should also talk again to your neighbour - explain clearly that if he doesn't fix the leak - and quickly - he will be responsible for all of the damage AND the leak will have to be fixed. If he fixes the leak now - then he's saving himself money. You might also check whether there is a home-owners' association for your apartment block - they would be able to help you too. SteveBaker (talk) 15:16, 15 February 2009 (UTC)

One comment: Just because there is water leaking from your ceiling doesn't necessarily mean it's coming from the apartment directly above yours. Water can leak from another apartment or even a roof ice dam, travel down the walls until it reaches a barrier, then travel between the upstairs floor and your ceiling until it finds a spot to leak through. StuRat (talk) 17:20, 15 February 2009 (UTC)

THere's some excellent advice above. In your situation I would I would contact your building insurer immediately in the form of a letter, marked Urgent, that states that you observed a water leak start, you believe it originates from Floor #1 and that you have informed (by a copy of the letter) the resident of the danger of damage. The logic here is that if damage and argument do arise, you have proof that you took steps to limit damage, and there is no accusation that provokes the other resident. Good luck. Cuddlyable3 (talk) 17:37, 15 February 2009 (UTC)

Is there any Green Agency at India

There are agencies that help corporates move towards achieving energy efficiency like 1 degree in Australia that helps News Corp. to reduce green house gas emition.

Is their any such service at India? or other parts world wide? —Preceding unsigned comment added by 117.196.164.211 (talk) 16:24, 15 February 2009 (UTC)

Past weather data

Please, is there an internet source for detailed past weather data? I'm looking for specifics (e.g., weather in Wales on a specific date), not long-term weather records. I realize that what I am looking for would require a large database.

Thank you, Wanderer57 (talk) 16:39, 15 February 2009 (UTC)

Try searching newspaper sites. If they've got their archives online, just pick the date you're interested in. B00P (talk) 17:26, 15 February 2009 (UTC)

TuTiempo. I found it a couple of months ago looking for historical weather data for Cape Town. The site is amazing, it has daily weather data for seemingly every city in the world going back decades, and not just temperatures, it has precipitation and cloud cover and everything. Knock yourself out! Zunaid 17:51, 15 February 2009 (UTC)

p.s. you have to click on the "climate" section in the left-hand column. The link for the UK is this. Zunaid 18:45, 15 February 2009 (UTC)

In the U.S. Weather Underground is very similar. I don't know what its like for locations outside the U.S. however. --Jayron32.talk.contribs 18:35, 15 February 2009 (UTC)

For specialist only...!

I'am working at construction feild , as asite engineer

now we're filling the spaces between the foundation according to cast the (slab on grade ) , to save time we are using single size aggregate instead of selected natural material , now and according to the plans there is a 15 cm layer of basecoarse under the slab , the question is this ...?

if i execute this layer , and we assume some how water did find its way to this layer , dont you think that the water will carry the fine material contained in basecoarse and move it down ward through the voids between single size agg. particles ,leading to deflection in the slab.

and , is the only purpous of (15 cm layer ) of single size to protect the slab concrete from being in contact with the natural fill material , and why ...?

i know its hard to understand all of this but i hope to get an answer ... ? —Preceding unsigned comment added by 94.249.40.92 (talk) 17:34, 15 February 2009 (UTC)

This is, essentially, a legal question. At least, it is a question which requires knowledge of building regulations in Jordania, knowledge of the plan of the building, the specifics and substrate of the buidling site, the reinforcement of the slab, the aggregate you are using for the fill, data on precipitation / groundwater and a few details more. I can´t imagine that you will get useful answers from a distance, even from static engineers. --Cookatoo.ergo.ZooM (talk) 18:34, 15 February 2009 (UTC)

we are using BS standards , we dont have our own i thought its going to be the same detailes for concrete structures assume , ordinary building use , low water table , warm claimate , crushed stone fill ( course aggregate used in concrete casting ). you will find a very excellent answers at www.cntractortalk.com . thanks

is it a coincedence too

I want you to follow this link , after you watch the video , please i need your objective opinion ...http:/www.metacafe.com/watch/98111/miracles_of_the_quran_12/

be objective .... thanks . —Preceding unsigned comment added by 94.249.40.92 (talk) 18:41, 15 February 2009 (UTC)

Many of us do not go to off-WP sites that could be anything. You can help us help you by asking your question, please, and by telling us what the link purports to show. We prefer to deal with facts, not opinions, objective or otherwise. Thanks ៛ BL ៛ (talk) 18:47, 15 February 2009 (UTC)