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April 5

HEADACE

Whats known cure for head ace and flu KENNEDY NEWTON (talk • contribs) 00:05, 5 April 2010 (UTC)

[medical advice removed --Tango (talk) 00:40, 5 April 2010 (UTC)]

We can't give medical advice, I'm afraid. There are lots of head ache and flu treatments available. I suggest you ask a pharmacist, they will almost certainly be able to help. --Tango (talk) 00:40, 5 April 2010 (UTC)

Moved discussion to Wikipedia_talk:Reference_desk#Headaches_and_medical_advice. --Tango (talk) 19:22, 5 April 2010 (UTC)

And the spelling you are looking for is most likely headache --Polysylabic Pseudonym (talk) 10:57, 5 April 2010 (UTC)

If we're removing Cyclonemin's answer, I'll at least reference our articles Headache and Influenza, which has all the information that was contained in his response. Buddy431 (talk) 22:37, 5 April 2010 (UTC)

Or better yet, these: Headache#Treatment, Management of chronic headaches, and Influenza treatment. Buddy431 (talk) 22:42, 5 April 2010 (UTC)

Restoring non-medical advice response, per talk page consensus: StuRat (talk) 19:39, 6 April 2010 (UTC)

Headache's vary significantly in type, but are usually relieved by some sort of analgesic (such as paracetamol) if they're minor. More serious types of headaches exist and depending on the type, various types of drugs can be given such as stronger analgesics or vasodilators. Sometimes headaches are indications of further, more serious diseases and act as a diagnosis aid. Influenza is a virus which is usually unpleasant but killed off by your immune system, and thus does not usually require treatment. However, in immunocompromised individuals (that is to say, those with a weaker immune system such as the elderly, AIDS patients, transplant patients etc) are often at greater risk because their immune systems may not be able to deal with the rapid replication of the virus. In such cases, doctors prescribe antivirals specific to the current influenza virus to try and boost your immune systems removal of the virus. Regards, --—Cyclonenim | Chat  10:59, 5 April 2010 (UTC)

bottom line: if aspirin or another nsaid doesn't make your headache or other ache (i.e. flu) go away, then modern medicine is more or less out of options. (not applicable to migraines, though)Gzuckier (talk) 06:23, 8 April 2010 (UTC)

Electrochemistry

"A biological cell is immersed in a 70. mM solution of NaCl at 37°C. The cell's membrane is permeable only to Na+ ions. When the system reaches equilibrium, a potential difference of 55.4 mV is measured between the inside and the outside of the cell, where the inside has the higher (more positive) potential. Calculate [Na+] inside the cell, assuming the amount of Na+ ions transferred is negligible compared to the total amount of Na+ ions in the solution."

I'm aware that, at equilibrium, the chemical potential of Na+ inside the cell equals the chemical potential of Na+ outside the cell, according to m = m° + RT ln a + ZFo. But what are F and o? I plugged in the values but don't get the answer. —Preceding unsigned comment added by 70.68.120.162 (talk) 01:59, 5 April 2010 (UTC)

I think F_o refers in this context to the Faraday constant. I might be wrong, though, because I haven't done any electrochem calculations in a long time. FWiW 24.23.197.43 (talk) 02:20, 5 April 2010 (UTC)

Let me just note that our Nernst potential article covers this. Looie496 (talk) 05:19, 5 April 2010 (UTC)

Cat Behavior - combination of "playing the piano" and mate mounting?

One of my adult female cats has exhibited a new behavior pattern for the past several months that I've never seen before. She has always occasionally "played the piano", the rhythmic massaging of invisible mammaries done by adult cats that were weaned too early. Recently, however, she has combined that with the neck-bite-and-hold that male cats do when they mount the female to mate. So, when I'm laying on the sofa or in bed under a blanket, she will mount my leg and firmly bite the blanket, then begin simultaneously massaging my leg with her forepaws while purring most determinedly. Has anyone else ever seen a cat (especially female) exhibit this behavior? Does anyone have any idea what sort of "needs" are behind this? I can understand both components alone, but together seems a bit odd! 61.189.63.142 (talk) 03:04, 5 April 2010 (UTC)

I'm not aware there's any real understanding of why cats knead. There are plenty of theories, of which yours is one, but we don't really know which one is correct (there may be multiple reasons). This is a key point because unless we know why cats knead, any speculation of why that occurs with some other behaviour is going to be speculation upon speculation. If you think these two behaviours don't go together because the cat is doing X for reason Y, if it's actually reason B this may change things completely. Purr#Reasons for purring is a somewhat related example. If you think your cat is purring because it's contented, what about if it's purring when it's sick, injured or dying? (Personally I like to jokingly say my cat is purring because he broke his bones [1]) BTW if you are concerned about any recent change in your cats behaviour, you should see a vet. Nil Einne (talk) 04:04, 5 April 2010 (UTC)

Note that female cats also grab their kittens by the loose skin on the back of the neck when carrying them. So, she may have kittens on the brain. This "broody" behavior seems especially common right after they are fixed. StuRat (talk) 04:11, 5 April 2010 (UTC)

All the female cats I've had exhibit this behaviour, which I haven't seen in any of the male cats. If she's biting and kneading at the same time, she's probably trying to suckle. I associate it with being relaxed - it usually happens before she goes to sleep. --TammyMoet (talk) 08:45, 5 April 2010 (UTC)

Thanks everyone! 61.189.63.142 (talk) 22:15, 5 April 2010 (UTC)

errr... I hate to suggest it, but it's possible you might be in the line for some kittens. pregnant cats tend to display some odd behavior. have you noticed her carrying small objects from one part of the room to another? --Ludwigs2 22:40, 5 April 2010 (UTC)

My experience suggests the behaviour happens in spayed females more than in entire females, so don't rule out the possibility unless you know she's been done! --TammyMoet (talk) 09:26, 6 April 2010 (UTC)

bioinformatics question

I need to compare amino acid and/or genetic sequences at work and it seems that my bioinformatics and BLAST skills are a little rusty. Can you point me to articles (better if they are fully accessible) regarding similarity, identity and homology of sequences? --121.54.2.188 (talk) 07:44, 5 April 2010 (UTC)

Do you mean BLAST, sequence alignment, BLOSUM ? --Rajah (talk) 10:55, 5 April 2010 (UTC)

Also relevant: Homology (biology), Conserved sequence, and Substitution matrix. -- Scray (talk) 11:30, 5 April 2010 (UTC)

Also keep in mind that Pubmed provides entire open-access books, e.g. Koonin & Galperin, the NCBI Handbook, Coffin, Hughes, & Varmus. -- Scray (talk) 15:18, 5 April 2010 (UTC)

This page from NCBI seems to be a good resource for everything BLAST related. It also has an email address and a link to a mailing list in case you need more specialist advice: [2] 131.111.185.75 (talk) 21:42, 5 April 2010 (UTC)

Sweet :) I think I'll be reading those articles and books this week.--121.54.2.188 (talk) 01:40, 6 April 2010 (UTC)

longest wavelength of EM radiation

In Electromagnetic spectrum, it is stated that the longest wavelength can be the size of the universe. If we use the equation relating frequency and Planck's constant then shouldn't the longest wavelength be 300,000 km ? as the energy of the photon must be integral multiples of Plankck's Constant. Also, the EM spectrum article states that it's continuous, but how can that be if energy is quantized. Maybe this is covered in another article like wave - particle duality, but I don't know. Can someone shed some light on this issue? Thanks! --Rajah (talk) 10:50, 5 April 2010 (UTC)

Energy does not have to a multiple of Planck's constant. You have assumed that lowest frequency is 1 Hz. Graeme Bartlett (talk) 11:51, 5 April 2010 (UTC)

You're confused. The energy spectrum is not quantised. Photons of any energy, no matter how big or small, can exist. Once you pick a photon frequency, then the number of photons for that frequency is quantised ---- that is no fractions of photons are allowed. Dauto (talk) 12:17, 5 April 2010 (UTC)

Energy levels for a certain system, like an electron in an atom, will be quantised, but that doesn't mean that energy in general is quantised. If your photons are being emitted by an excited atom, then there will be a minimum photon energy corresponding to the smallest gap between energy levels of the atom, but there are other ways for photons to be created and, once they have been created, their energies can change (we call that redshift or blueshift). --Tango (talk) 14:30, 5 April 2010 (UTC)

Tango, the energy levels of an atom have an accumulation point as the energy aproaches the continuum (free particles) so the smallest gap between energy levels tend to zero. Dauto (talk) 14:37, 5 April 2010 (UTC)

From a practical point of view, it is very hard to generate electromagnetic waves with wavelengths much larger than an antenna. As such, it is pretty uncommon on Earth to ever observe EM waves as low as, say, 100 Hz; but ultra low frequency and extremely low frequency waves do exist, often related to geological and geomagnetic processes, interactions between Earth and its solar environment, or extraterrestrial/extrasolar sources. Nimur (talk) 15:24, 5 April 2010 (UTC)

Oh, yes, I apologise for my mistake. I should look these things up rather than try an remember my one course in Quantum Mechanics several years ago. --Tango (talk) 15:30, 5 April 2010 (UTC)

There does not seem to be any lower limit for EM waves. They could be orders of magnitude lower in frequency that 1/second. This is despite the effect that an antenna for efficient transmission and reception would have to be beyond humongous. The only limit wold be one of definition. Edison (talk) 18:53, 5 April 2010 (UTC)

You really think that EM waves less than 100 Hz are "pretty uncommon"? Well, just take your portable radio and stand under a high-voltage power line, and see what it does to the reception! The fact is, EM waves with a frequency of exactly 60 Hz are actually pretty darn common on Earth -- any high-voltage power line generates them to a greater or lesser extent. Now it's true that such low-frequency sources only radiate very weakly in relation to the amount of current flowing through them, and that it would take an antenna that's "beyond humongous" in length to transmit such waves -- but if you're talking about a transmission line that's part of the national grid, it would typically be hundreds of miles long (thus forming essentially a super-duper-long wire antenna) and carrying hundreds of millions of amps at maybe 750,000 volts, which would emit a significant amount of 60 Hz radio waves even if only a fraction of a percent of the total energy was radiated. 24.23.197.43 (talk) 04:55, 6 April 2010 (UTC)

Do you understand that your portable radio is picking up harmonics of 60 Hz, and not 60 Hz? Unless your portable radio antenna is about 5000 kilometers long, and connected to a tuned circuit that resonates at such low frequencies, you are not picking up 60Hz waves. Nimur (talk) 20:56, 6 April 2010 (UTC)

OK, I may be wrong about the radio picking up the 60 Hz waves; but that doesn't change the fact that the 60 Hz waves are indeed emitted by the power line, along with the higher harmonics that are the ones responsible for radio interference. It's pretty much the same thing as when a plane crashes in the ocean but there's nobody around to hear it... 24.23.197.43 (talk) 02:23, 7 April 2010 (UTC)

One or two thousand amperes, more like. [3] --Heron (talk) 18:20, 6 April 2010 (UTC)

The U.S. and Soviet/Russian navies used "super low frequency" or "extremely low frequency" transmissions at 76 Hz and 82 Hz respectively to send messages to their submerged submarines. The Sovs put the ground electrodes 60 kilometers apart. The U.S. used electrodes 52 km apart. The input power was a reported 660 kilowatts, while the radiated power was only a few watts, since the antenna was a tiny fraction of a wavelength, but the encrypted transmissions could be received worldwide by deeply submerged submarines. (The submarines couold not reply at that frequency, but could let up a radio bouy to send at more normal frequencies if stealth was not a concern). There were concerns about the effects on humans and animals of the resulting widespread electromagnetic fields. The system could be used to send nuclear attack authorization to ballistic missile submarines, so it had to transmit signals all the time, and could not be kept in standby non-transmitting. To suddenly start transmitting during a time of world tensions would have been a giveaway that something was up. Edison (talk) 15:26, 6 April 2010 (UTC)

Wasn't the bandwidth really low on that comm method? Googlemeister (talk) 16:37, 6 April 2010 (UTC)

Experimental psychology effect - can't remember name

Resolved

I've had no luck with Google and I really need an answer to this question, so I'm going to be obnoxious and cross-post it from the humanities desk to draw some attention.

I'm trying to find the name of a psychological effect I remember reading about a while ago. (It might have been in SuperFreakonomics, a book I no longer have.) The effect was that people tend to prefer to work for free over working for a small amount of money, because working for free feels like charity but working for very little feels like devaluing your accomplishments. Anyone know what the name of this effect is, or a citation for the experiment?

Please don't kill me. I'm really a nice guy, you know. « Aaron Rotenberg « Talk « 17:40, 5 April 2010 (UTC)

I can't say I know that this effect has a name, but Dan Ariely writes about this kind of thing in Predictably Irrational, which unfortunately I don't have on hand.--Rallette (talk) 18:19, 5 April 2010 (UTC)

I think your thinking of:Cognitive dissonance theory (Leon Festinger and Carlsmith 1959) which shows that getting a zero reward can increase liking for the task compared with receiving a small positive reward. see also:[4]--Aspro (talk) 18:38, 5 April 2010 (UTC)

Of course, free t-shirts are a more powerful motivator than either low pay or charity. :-) —ShadowRanger ^(talk|stalk) 19:04, 5 April 2010 (UTC)

Who said free t-shirts? Where? What do I need to do?! Dismas|^(talk) 20:40, 5 April 2010 (UTC)

Dismas you want to volunteer at the Great British Beer Festival and you will get your free staff T-shirt! --TammyMoet (talk) 09:24, 6 April 2010 (UTC)

That's good enough. The "introducing a penalty for parents who are late picking up their children from kindergarten can actually increase tardiness" example is one of the ones I remember reading about. I guess there isn't a standardized name for the specific effect, though. Thanks! « Aaron Rotenberg « Talk « 23:26, 5 April 2010 (UTC)

Cracking a Chest

When doctors refer to cracking a person's chest open, what is the technical name for this surgical procedure? Thanks 92.11.43.155 (talk) 21:28, 5 April 2010 (UTC)

Well, when they're operating on the heart or nearby related organs, it's called open heart surgery. Not sure if there are other operations that use this technique. —ShadowRanger ^(talk|stalk) 21:43, 5 April 2010 (UTC)

May be sternotomy. Dauto (talk) 21:49, 5 April 2010 (UTC)

That's right, it's a specific type of thoracotomy. By the way the definition of open heart surgery on the cardiac surgery page contradicts that on the median sternotomy page. Someone should probably check that out, but I'm afraid I can't as I'm not really meant to be editing wikipedia at all at the moment. (self imposed wikibreak due to exams, and yes I know that I shouldn't be posting this now) 131.111.185.75 (talk) 21:53, 5 April 2010 (UTC)

Thanks. Thoracotomy was just what I was looking for. 92.11.43.155 (talk) 01:01, 6 April 2010 (UTC)

(ecX2) See Cardiac_surgery#Open_heart_surgery. StuRat (talk) 21:51, 5 April 2010 (UTC)

Railroad Engineering

Hi,

I was developing some content for a train-simulation program..

I have a LOT of questions..

I'm asking because I was developing some content for a train-sim and wanted to make the objects 'look' accurate.

i) Does anyone here have a simple formula for converting an axle loading value into a rail weight? (It's something the article on axle loading should maybe have but doesn't)

ii) Typical weights and "rail profiles" for typical 2ft industrial lines would be? ( I've got links to some data for typical US profiles, although I imagine the 'official' standards are tightly controlled.) I am guessing that US logging lines used heavier rails then the Welsh Slate lines though :)

iii) An ISBN or citation for a standard (preferably metric) work on how you lay out trackwork for various gauge construction.. Such works also usally have the formulae for curve limit calculation for various gauges and wheelbases..

iv) A general reading list on the subject of 'industrial' narrow gauge railways ShakespeareFan00 (talk) 23:18, 5 April 2010 (UTC)

Interesting! I actually worked on commercial railroad simulators for Burlington Northern back in the early 1990's - and we didn't need any information in that much detail! Sadly, that means I'm of no help whatever in answering your questions - sorry. SteveBaker (talk) 02:44, 6 April 2010 (UTC)

How is 2 feet an "industrial" gauge? It is less than half standard gauge, and sounds like something you might find at a narrow gauge museum or a little toy ride-on train at an amusement park. Google Book search is your friend for old technical information, because some of it is fully viewable, unlike technical information from recent years. See "Railway engineering" (1899), "Railway engineeering" (1908), "Railway maintenance engineering" (1919), "Steel rails" (1913), "Manual of the American Railway Engineering Society" (1921), Manual of recommended practice for railway engineering and maintenance of way" (1907) and in a limited view "Practical railway engineering" (2005). A cursory search through some of the old and the one new ref did not turn up the terms "axle loading" or "rail weight," though. Where did you find the terms in use? Edison (talk) 14:47, 6 April 2010 (UTC)

Searching Google books for "axle loading" "rail weight" turned up one reference: "Operation and maintenance of diesel-electric locomotives", U.S. Army, (1989)‎ - Page 174 which says "allowable axle loading varies with the weight of the rail, speed of operation, and other factors." "Rails weighing 60 pounds per yard or less will handle about 500 pounds of axle load (2 wheels) per pound of rail weight (that is, about 30,000-pound axle loading for 60 pound rail, 25,000-pound axle loading for 50 pound rail). As rails become heavier, the allowable axle loading increases to an approximate value of 700 pounds per pound of rail for 90 pound rails (that is 63,000 pounds)." No idea if the data extrapolate down to very small and light rails. Incidentally, U.S. practice has been 8 wheels (4 axles) per car, while I have seen old European railstock with 2 axles per car. Edison (talk) 15:03, 6 April 2010 (UTC)

Hmm, Thanks for the first set links, they don't seem to be on 'full' view in the UK though (longer copyright terms perhaps:( ).

2ft Guage certainly WAS an industrial guage, and something similar is still used in some parts of Europe, IIRC parts of New England also had 2ft lines associated with 'forestry'? 212.225.121.81 (talk) 23:34, 6 April 2010 (UTC)

Indeed, there are plenty of induxtrial lines in our Category:Two foot gauge railways. DuncanHill (talk) 08:59, 7 April 2010 (UTC)

April 6

Terraforming Venus

The first problem for colonizing Venus would be the immense atmospheric pressure. Venus itself is slightly smaller than Earth, so I assume it isn't the increase in the solid mass that is causing the pressure? Is it simply the density of the atmosphere that causes the pressure? According to our article it's about 2.5 times thicker than our own. How might we reduce the size of its atmosphere? Could we somehow siphon it off into space? Perhaps we could transport it to Mars to help build an atmosphere there?

Next is the composition of the atmosphere. How might we dispose of all the harmful gases such as sulpher dioxide and hydrochloric acid? Then there's also the carbon dioxide. There is a huge selection of life from our planet that would be capable of converting this carbon dioxide into oxygen, but the problem is none of it can survive the extreme temperatures of Venus, which are caused by all that CO2. We're in a catch 22, we need to get rid of the CO2 to make the planet habitable, but we can't get rid of it until it is habitable. Not even hyperthermophiles could survive those temperatures. So what could we do? Apparently the temperature in the area from 52.5 to 54 km above the surface has temperatures of 20- 37 degrees Celcius, with pressure only slightly lower than that of Earth. We might grow plants in this area, but how could we suspend them at that altitude?

Then there's the massive amount of volcanic activity ready to undo any changes we make to the atmophere. Is there any way we could control this? I can't think of anything at all.

And finally there's the magnetic field. According to our article on the subject the only reason for the lack of a magnetic field on venus is the lack of convection in the mantle; i.e. the mantle and core are at comparable temperatures. How might we create a temperature difference? Nuclear weapons?--92.251.137.62 (talk) 00:08, 6 April 2010 (UTC)

I think we should wait until after Mars is fully terraformed to even think about doing Venus. They only part I can answer is that we could use blimps to hold plants in the upper atmosphere. They could be black on top to absorb solar heating and could also be filled with lighter gases. StuRat (talk) 00:22, 6 April 2010 (UTC)

I think it might be an idea to merge the moon and mercury into mars to make it bigger so people don't have to adapt to life on earth.--92.251.137.62 (talk) 00:27, 6 April 2010 (UTC)

Do you know how much energy you would need to get the Moon and Mercury into Mars' orbit? And then you have the problem of merging them without just destroying them all. It is completely impractical. --Tango (talk) 00:44, 6 April 2010 (UTC)

I think it's obvious from the title that this is completely hypothetical and certainly won't be possible, never mind practical, for probably thousands of years. C'mon I'm sure you can use your imagination.--92.251.137.62 (talk) 00:50, 6 April 2010 (UTC)

Plus, taking the Moon away from the Earth could cause all kinds of nasty consequences for us here on Earth (like changing the Earth's rotation speed, messing up the magnetic field, major climate change, etc.) Definitely not a good idea, even if it was remotely possible. 24.23.197.43 (talk) 05:04, 6 April 2010 (UTC)

If you have the energy available to move the Moon into Mars' orbit, then you can easily deal with those problems. --Tango (talk) 15:17, 6 April 2010 (UTC)

If people are interested, moving the Moon from Earth's orbit to Mars' orbit, ignoring the Earth and Mars and just considering the Sun and Moon, would take the total energy produced by the Sun, emitted in all direction, for 16 hours. That is a ridiculous amount of energy. --Tango (talk) 15:27, 6 April 2010 (UTC)

Not that it matters, but I got 59 hours. Dragons flight (talk) 18:39, 6 April 2010 (UTC)

Same order of magnitude, so close enough! --Tango (talk) 21:47, 6 April 2010 (UTC)

While you might be able to fix the problems involved with removing the Moon, a much lower tech level could just skip the Moon itself and crash Mars's moons onto the surface and bring some of the larger asteroids from the (relatively) nearby asteroid belt in to add mass. No need to fsck up the Earth and expend huge amounts of energy to enable the Moon to escape Earth's gravity when you've got a whole asteroid belt to cherry pick. Hell, with the asteroid belt, you just have to decelerate an asteroid at the right time and the Sun's gravity will do the work for you. With the Moon, even with near perfect timing to maximize the use of a slingshot maneuver using the Earth's gravity you'd still be fighting the Sun the whole way. —ShadowRanger ^(talk|stalk) 18:46, 6 April 2010 (UTC)

Moving closer to the Sun is no easier than moving further away. In one you have to accelerate the object and in the other you decelerate it, but that's the same thing as far as energy is concerned. Also, the total mass of the asteroid belt is only 4% that of the Moon (and Mars' moons don't add much to that). --Tango (talk) 21:47, 6 April 2010 (UTC)

See Terraforming of Venus. There are various ideas there on how to do it, but none of them particularly feasible, even assuming reasonable future technology. --Tango (talk) 00:44, 6 April 2010 (UTC)

seeing red

I happened to be on a path with a translucent green roof. After getting out of the path it seems that all that I look at have a tinge of red. The same thing happened when I was looking on an translucent orange window of a jeepney but it seems that other things I look at this time have a bluish tinge.--121.54.2.188 (talk) 01:49, 6 April 2010 (UTC)

See afterimage, or more generally, sensory adaptation. TenOfAllTrades(talk) 02:06, 6 April 2010 (UTC)

Your eyes have red, green and blue sensors - when you see a lot of one color, the brain dials down the output of sensor(s) that pick up that color. When you step out into normal light, it takes a while for the brain to adjust - and hence, everything takes on a tinge which is complementary color of the one you'd been looking at before. So in green light, your green sensors are dialled down. When you step into white light, green is suppressed and everything is seen in red/blue only. The color that is a mixture of red and blue is "magenta" - which is a reddish purple. Orange (which is really dark yellow) is a mixture of red and green - so in yellow/orange light, the red and green sensors are suppressed - and when you enter white light, the blue sensors are the most active. Hence, the colors you saw pretty much exactly fit the theory. The effect fades over maybe 10 seconds as your eyes return to normal.

You can do an experiment to prove this. Click a couple of times on the image at right until it's only thing in your browser window - make the window full-screen. Now, stare fixedly at the nose for a full 30 seconds - then immediately look at the blank part of the screen. You should see a 'normal' colored picture of our glorious leader. This works because the picture at right is a colored "negative" of the desired image. When our eyes start to shut down the blue sensors - we'll see flesh-tones. (You may need to quickly blink to see it a little better.)

SteveBaker (talk) 02:32, 6 April 2010 (UTC)

I read once that one reason for Scrubs (clothing) being green was to reduce the distraction of green afterimages from extended staring at brightly lit surgical procedures. Our article on scrubs does not mention that particular reason, might try to see if I can find a source later. Vespine (talk) 04:39, 6 April 2010 (UTC)

Oh! To contrast with all of that red blood splattered everywhere?! Well, it's possible I suppose. So I suppose the reason all of the security guys on the Starship Enterprise wear red is to avoid this exact effect when massacring Romulans? SteveBaker (talk) 13:17, 6 April 2010 (UTC)

I think they are designed to contrast with blood, but so that you can tell if there's blood on your scrubs and change them before infecting other patients. Blood also shows up nicely against a traditional white nurse's uniform. However, now they prefer patterned prints, which seem more designed to hide contamination than to make it obvious. StuRat (talk) 13:55, 6 April 2010 (UTC)

You can tell that white light stimulates blue sensory receptors more because when you are in bright light and go into a dim room, every thing has a bluish-violet tinge. --Cheminterest (talk) 20:29, 7 April 2010 (UTC)

Red,Green,Blue

Not really. There is actually a much more complicated reason for that...it's to do with the shift from 'Mesopic vision' to 'Scotopic vision' and an effect called the Purkinje effect. This becomes a very complex topic once you really start digging into it. But in normal light levels, our eyes are actually quite a bit less sensitive to blue than to red and green light...but our brains are good at compensating for that, so it's not something you generally notice. But if you look at the image at right, you'll see that the blue patch looks much darker than the green...that's not an artifact of picture - or your computer screen - its your eyes! SteveBaker (talk) 02:35, 8 April 2010 (UTC)

What causes color?

Color is clearly determined by what wavelengths of light are transmitted off an object, but why do things absorb certain wavelengths and reflect others? Why, for example, are crystals of copper sulfate pentahydrate brilliant blue (while its anhydrous form is white), rather than any other color (or colorless)? Color clearly depends to some extent on structure, as evidenced by the various allotropes of phosphorous or the copper sulfate example above, but then again, just loose nitrogen dioxide molecules floating around make a brown gas. On a related note, what would cause something like glass to be transparent and colorless? Thegreenj 02:20, 6 April 2010 (UTC)

The article on Transparency and translucency probably answers all of your questions. It is a pretty good introduction to the physical properties of color and light from what I can see.

Note of course, unstated above, is that it is the brain that translates wavelengths into what we call "colors" (which is a perceptual property, not a physical one). So to be perfectly consistent, you'd want to not say "brilliant blue" but "reflects EM waves in the (insert measurement) range." It's the brain that makes it "blue", based on its interpretation of signals from your eye hardware. (The brain could be wired differently—some animals can't distinguish between wavelengths that humans can, and can see some wavelengths that humans can't.) --Mr.98 (talk) 02:39, 6 April 2010 (UTC)

As for colors, each atom has a bunch of electrons at a small number of specific energy states (called quanta), Light hitting them causes them to change energy states, and when they return to the original state, they radiate photons at specific frequencies, or colors. This is part of quantum mechanics. StuRat (talk) 13:30, 6 April 2010 (UTC)

A minor (but important) quibble — quanta (singular quantum) are discrete packets of energy (generally associated with transitions between energy levels), not the energy levels themselves. That is, photons are quanta of electromagnetic energy. In a system that can be modelled as having discrete energy levels (as in the example of electrons bound to an atomic nucleus), one can describe the associated energy levels as quantized; the arrangement of electrons (which will determine the system's energy) can be described as its quantum state. TenOfAllTrades(talk) 14:09, 6 April 2010 (UTC)

Thanks for the responses! One more follow-up question: are there models that can be used for theoretical predictions EM absorption/emission based on a molecular structure? Thegreenj 02:57, 7 April 2010 (UTC)

Yes, I believe there are. StuRat (talk) 10:39, 7 April 2010 (UTC)

What's the nasty stuff in coal ash?

Could someone who can read this paper please list the "minerals and leachable metals" it names as primary sources of toxicity? 99.25.114.26 (talk) 07:53, 6 April 2010 (UTC)

What is leachable is going to depend on what is in the coal and slag to start with. See Fly_ash#Groundwater_contamination, etc.--Aspro (talk) 08:15, 6 April 2010 (UTC)

Oh, great, you just happened to catch me reading up on coal-to-liquids technologies! Well, since these topics are closely related, I'll tell you what my source (Higman and van der Burgt) says about leachable toxic metals in coal ash. Here's a comprehensive list of the toxic metals and their concentrations:

Arsenic, 2.1 ppm (volatile)

Boron, 35 ppm (relatively nontoxic)

Barium, 130 ppm (but not all of it is in leachable form)

Beryllium, 1.2 ppm

Cadmium, 0.07 ppm (volatile)

Cobalt, 3.5 ppm (somewhat radioactive; volatile if reduced)

Chromium, 7.0 ppm (only slightly leachable if reduced)

Copper, 9.2 ppm

Mercury, 0.13 ppm (volatile)

Manganese, 84 ppm (not very toxic)

Nickel, 10 ppm (volatile if reduced)

Lead, 14 ppm

Antimony, 0.57 ppm (may be volatile if reduced)

Selenium, 3.1 ppm (volatile)

Strontium, 316 ppm (radioactive)

Thorium, 8.4 ppm (slightly radioactive, nonleachable)

Uranium, 2.1 ppm (radioactive, practically nonleachable)

Vanadium, 17 ppm (partially leachable)

I should also mention that most coal-to-liquids processes are much better environmentally than conventional coal-fired power stations, because they produce little if any fly ash, and because the bottom ash comes out in the form of an inert non-leachable slag that traps all the toxic metals instead of spreading them far and wide. As for the volatile metals, instead of simply being dumped into the atmosphere as in a conventional power plant, they enter one or more of the gaseous byproduct streams, from where they can be scrubbed relatively easily. Coal-to-liquids also allows the sulfur to be removed and recovered almost completely, because it's removed from the coal as H₂S, which is readily scrubbed from the off-gas stream by a wide variety of methods, and can be converted to elemental sulfur, whereas in a conventional plant, it goes into the flue gases as SO₂, which can only be recovered as calcium sulfate, a relatively low-value material. 24.23.197.43 (talk) 09:00, 6 April 2010 (UTC)

See also Polycyclic aromatic hydrocarbon, soot, and fly ash. 92.29.111.79 (talk) 22:42, 6 April 2010 (UTC)

Soot and PAHs are not metals and therefore are technically outside the scope of this discussion; however, they are indeed found in fly ash and are potentially harmful to human health. (Note also that coal-to-liquids technology allows these to be recycled to extinction, which is rarely if ever possible with conventional coal-burning technology.) 24.23.197.43 (talk) 01:17, 7 April 2010 (UTC)

The OP asks "What's the nasty stuff in coal ash?" 78.149.173.243 (talk) 15:06, 7 April 2010 (UTC)

True, but then he/she specifically asked about "minerals and leachable metals". FWiW 24.23.197.43 (talk) 05:31, 8 April 2010 (UTC)

2012-- mayan civilization

is the hoax about the end of earth in any scientific way correct? if its so what scientists are doing to save the earth?--Myownid420 (talk) 12:45, 6 April 2010 (UTC)

• See Mesoamerican_Long_Count_calendar#2012_and_the_Long_Count, which states "...stated that "We have no record or knowledge that [the Maya] would think the world would come to an end" in 2012. As well as 2012 phenomenon. Dismas|^(talk) 12:50, 6 April 2010 (UTC)
• No, and consequently, not anything they don't do anyways. See http://www.2012hoax.org/ for detailed rebuttals of all the various doomsday fantasies. --Stephan Schulz (talk) 12:52, 6 April 2010 (UTC)

The Mayan clock has a whole bunch of cycles built into it. These are like the hands going around on a modern-day clock - or the cycles we have of months, years, decades, centuries and millenia. For the Mayans, 2012 would be like the end of a millenium for us. Of course, quite a few nut-jobs thought the world would end on Jan 1st 2000, but the Mayan calendar is even more attractive to those kinds of people because it's that little bit more obscure. The Mayans didn't predict that the world would end - and even if they did, what the heck did they know that we don't? The world (and the universe in general) are ruled by 'chaotic' (in the mathematical sense) systems. Making any precise predictions (to within an accuracy of a single day) for more than a few tens of years into the future is essentially impossible - not just because we can't measure things that accurately - but also because the fundamental mathematics of chaos theory doesn't permit that kind of precision.

So the Earth doesn't need saving (well, not from the first cycle of the Mayan calendar ending). Hence, scientists aren't doing anything special because of it. Now, can we all please go back to worrying about our lack of defense against killer asteroids, or the all-too-real certainty of disasters from global climate change and the certainty that we're about to run out of materials like copper that are essential to our present way of life? If the general public spent half as long worrying about those things as they do about ridiculous nonsense like Mayan calendars, the world would be a much more secure place! SteveBaker (talk) 13:09, 6 April 2010 (UTC)

You might be interested in a similar discussion over at Wikiversity, which focuses on the "galactic alignment" around that date: [5]. StuRat (talk) 13:10, 6 April 2010 (UTC)

That's nuts! Nothing else in our galaxy is remotely close enough to affect us - and any alignment would be tough to define given all of the speed-of-light issues involved. Also, things move so incredibly slowly that if some grand alignment were happening in just a couple of years, we'd already be feeling whatever effect there is supposed to be. "Galactic alignment" is a deeply stupid idea! SteveBaker (talk) 03:24, 7 April 2010 (UTC)

I don't think gravitational effects are relevant, it's meant to be some type of "sign from God that Armageddon is approaching". Not that I believe any of it, of course. StuRat (talk) 10:27, 7 April 2010 (UTC)

But given that assumption, what makes anyone imagine we'd get any warning? God could snap his/her/its' fingers/hooves/tentacles at any time and end the universe. This is why we call unpredictable events "Acts of God". SteveBaker (talk) 20:23, 7 April 2010 (UTC)

Perhaps the god(s) are giving humanity time to repent ? In any case, various holy books talk about signs coming before the end, although I don't know of any that mention galactic alignment specifically. StuRat (talk) 15:19, 8 April 2010 (UTC)

Even assuming that global climate change is happening like they say and will lead to big disasters for the civilized nations somewhere down the road (and there is real dispute about both these claims), it's not nearly as immediate as the threat that global jihad poses to our freedom and our way of life. If the public spent more time worrying about that danger and less time about stuff that won't happen until many years from now, we would all be much safer. 24.23.197.43 (talk) 01:26, 7 April 2010 (UTC)

I really don't agree about that. Sure, the terrorists can make a lot of trouble - but I don't see them being able to produce world-wide "end-of-world" types of effects. Even the worst-case scenario of them getting hold of a nuclear weapon would likely only take down one city - it would be tremendously upsetting and even somewhat disruptive - but life would go on in pretty much the same way elsewhere. I would expect to see chaos on the scale of Hurricane Katherina...possibly more if it were NewYork, Washington or someplace like that - but it's not an end-of-world scenario. Incidentally - if you still don't believe that Global climate change is real - you should maybe actually read that article you linked to. SteveBaker (talk) 03:24, 7 April 2010 (UTC)

Steve, according to the latest Rassmussen polls, most Americans disagree with you about global warming. As for global jihad, have you considered that if Pakistan decides to make a nuclear terrorist attack, they could blow up several atom bombs in different coastal cities at the same time Al-Qaida fashion and not only destroy several cities at the same time but also cripple our foreign commerce for up to several years, with devastating economic consequences? No, it wouldn't be the end of the world, but pretty darn close to it. Also, by "global jihad" I mean not just terrorism, but also "stealth jihad" (meaning efforts by Islamic organizations to pass Sharia-type laws in a number of Western nations, including the USA). This is possibly an even bigger danger in the long run than ordinary terrorism, even of the mass-casualty variety. 24.23.197.43 (talk) 05:50, 8 April 2010 (UTC)

Sure and as I suggested below, Barack Obama or the Russian top brass could do far, far worse. Does it mean it makes sense for us to spend a lot of time worrying about such possibilities? Not really. Your claims of stealh jihad are even more nonsense without any evidence. And frankly, I don't really care what most Americans believe. Most Americans don't believe in evolution either despite the fact I can count on the fingers of my hand the number of biological scientists who actively dispute it. What most people believe clearly doesn't tell us much about reality. Nil Einne (talk) 16:11, 10 April 2010 (UTC)

Indeed many would argue people are already way too worried about 'global jihad' in comparison to the actual threat posed. And even without "end of world" type effects, you only need one or two major natural disasters or starvation in a few places for the number of deaths resulting from global warming to dwarf anything from 'global jihad' to now Nil Einne (talk) 07:57, 7 April 2010 (UTC)

Nil Einne, the danger from global jihad is not just people getting killed, but even more so the fact that the Islamics' ultimate goal is to eliminate secular democracy and replace it with totalitarian Islamic fundamentalism. See my reply to Steve Baker, just above your comment. 24.23.197.43 (talk) 05:50, 8 April 2010 (UTC)

There is little evidence for your claims that it's the goals of most let alone all people involved in 'global jihad', and little evidence there is significant risk so... Nil Einne (talk) 16:11, 10 April 2010 (UTC)

That's what the definition of jihad is -- a holy war for the purpose of spreading Islam. Did you just not know this, or are you purposely muddling the issue in order to minimize the threat of jihad? (BTW, your user page says that you're from Malaisia, which is a majority Islamic country, so...) 24.23.197.43 (talk) 02:52, 11 April 2010 (UTC)

Obviously. 9/11 did not even make a blip on world-wide death rate. Katrina alone killed 1800+ people, nearly 2/3rds of the direct deaths toll of 9/11. The 2010 Haiti earthquake killed between 30 and 100 times more people than 9/11, and the 2004 Indian Ocean earthquake was of the same order of magnitude. Terrorists simply do not play in the same ballpark - it needs a evil empire to compete. --Stephan Schulz (talk) 12:33, 7 April 2010 (UTC)

Just because terrorists haven't killed millions yet, that doesn't mean that they won't some day be able to, with nuclear and biologic weapons. StuRat (talk) 15:11, 8 April 2010 (UTC)

Thanks for the common sense, StuRat -- this should be obvious to everyone, even someone as out of it as Stephan Schultz. Clear skies to you! 24.23.197.43 (talk) 00:13, 9 April 2010 (UTC)

Sure, and Barack Obama and the top brass in the US could go nuts and decide to take out the whole world in our foul swoop. That doesn't means we should spend all our time worrying about this possibility when there are far bigger problems to worry about Nil Einne (talk) 16:11, 10 April 2010 (UTC)

Sure, they could nuke the whole world, but the question is, why the bloody hell would they? There's no plausible motivation for them to do that, and you know it! On the other hand, Ole Goatface would surely nuke everyone in America if he could, but fortunately he can't (thank God for that!) 24.23.197.43 (talk) 02:52, 11 April 2010 (UTC)

Stephan Schulz, how DARE you call my wonderful country an "evil empire", you stinking anti-American bastard?! If you don't agree that terrorism is a significant threat, you're welcome to say so and give whatever evidence you have to support your views, but don't you dare insult the best nation in the whole wide world, you son of a witch! 24.23.197.43 (talk) 05:50, 8 April 2010 (UTC)

I didn't. You deduced this from the links I gave. What does that tell you? --Stephan Schulz (talk) 06:21, 8 April 2010 (UTC)

Oh yes you did, you low-down liar -- the links clearly imply that (according to you) the USA is an "evil empire" because of the Iraq war! Don't you try to say one thing one day and deny you ever said it the next day, your statements are on public record here and smart people can see right through your obfuscation! Now, get lost! 24.23.197.43 (talk) 08:05, 8 April 2010 (UTC)

"the links imply" - that's the point. --Stephan Schulz (talk) 08:16, 8 April 2010 (UTC)

That's rubbish and you know it -- the articles you linked merely state the claims re. the Iraq war, it's YOUR choice of words for the links that implies the conclusion (namely, that the USA is an "evil empire"). Stephen Schultz, you can try to bullshit everyone with your word games like some sleazy lawyer from a pulp-fiction novel, but over the past year or so I've learned to see right through your tricks! And FYI, if you tried this kind of sophistry in an actual courtroom, I bet you all you want that you'd be disbarred before you can say "cat in the hat"! 24.23.197.43 (talk) 00:13, 9 April 2010 (UTC)

Uh, boy. Let me point out that in most religious traditions (the Mayans included, as best I can tell) the 'end of the world' is a 'human' event, not a 'world' event. It usually means a broad sea-change of some sort in the nature of human society. Only the far fringe of religious ideology interprets the end of the world as a physical ending to the world.

Frankly (as an American) I am far more concerned about the actions of powerful nations than of terrorists and small nations. Even considering a world in which Pakistan, Iran, and North Korea have nuclear weapons, the maximum yield they could produce would (at best) kill a few million people and stir up a whole lot of drama - they do not have the resources to pose a serious threat to modern society. Terrorists are even weaker, and despite their supposed goals are basically incapable of changing the social order directly. however, the US, China, and Russia (for the short list) have the resources to make the world largely unfit for human life, either through warfare or through industrial and commercial pollution.

And IP-person: chill out the jingoistic crap. --Ludwigs2 15:58, 8 April 2010 (UTC)

First tell Stephan Schulz to quit his America-bashing crap, and then you can tell me to chill out the "jingoism", as you put it. He's the one who started this whole shouting match by calling our country an "evil empire" -- just check out his first comment in this section. And BTW, you're wrong to worry about nuclear warfare between civilized nations like the US, China and Russia 'cause they're all smart enough to know better than to start a nuclear war among themselves (which is not the case for Iran and Pakistan). 24.23.197.43 (talk) 00:13, 9 April 2010 (UTC)

Ok listen, just because someone on here says something you disagree with doesn't give you a free pass to completely flip out.

That said, the claim that the US is an evil empire is pretty silly if you know anything about US politics. We may do things that are belligerent and harmful, but it's not intentional harm and it's not as if we've been profiting off these blunders. These recent wars have cost the US hundreds of billions of dollars, thousands of lives, and were initiated at least with the expectation by those who supported them that they would make the world at large more safe.

But I laughed out loud when I read "the threat that global jihad poses to our freedom." Are you talking about how the terrorism obsessed are undermining the rule of law in the name of security? Also do you seriously think that a poll of Americans provides evidence for or against the existence of human caused climate change? Maybe Rasmussen can tell me about the Higgs boson too. That would be much cheaper than this whole LHC thing. Rckrone (talk) 07:31, 9 April 2010 (UTC)

I've clarified this already in plain English, that by "jihad" I meant not just terrorism, but also "stealth jihad" (i.e. efforts by Islamic groups to lobby for Sharia-type laws in Western nations). Those efforts, not terrorism, are the main danger that Islam poses to freedom. Can't you read simple English? 24.23.197.43 (talk) 04:55, 10 April 2010 (UTC)

Again please provide some evidence for your claims of this supposed risk due to 'stealth jihad', or stop talking such nonsense. Perhaps you really should have left when you said goodbye? Nil Einne (talk) 16:11, 10 April 2010 (UTC)

OK, I'm going by memory here, but this was in an accredited news source from Minnesota: a few years ago the Minneapolis city council made an ordinance that allowed Muslim taxi drivers to refuse service, at their discretion, to anyone who has any alcoholic beverage (whether open or not) on their person or in their luggage. That's just one example of "stealth jihad" in America; there may be others, but I don't happen to remember the details at this time. I should say, though, that "stealth jihad" is currently more of a problem in western Europe than in America. 24.23.197.43 (talk) 01:40, 11 April 2010 (UTC)

As far as saying goodbye, Nil Einne, I've made up my mind that I will never answer any question from you again, even if it's in my area of expertise (which is organic chemistry). So if you want advice on how to clean that crusted-over rice cooker, you better ask someone else. 24.23.197.43 (talk) 01:44, 11 April 2010 (UTC)

Not to further inflame this ("evil empire" was tongue-in-cheek, as, I hope, most here recognized), but the recent wars have not cost the US hundreds of billions of dollars, they have cost the US government (and, by logical extension, the US taxpayer) hundreds of billions of dollars. By far the largest part of that money flows back into the US economy, buying MRE's, Apaches, Hummers, ammunition, paying soldiers, shipping supplies, and maintaining the whole logistic train of a modern army. This is almost certainly more than 90% of the effort. And while every dead, US or Iraqi, is one to many, even the most conservative estimates show 10 times more Iraqis dying - and the peer-reviewed Lancet studies show two orders of magnitude between US and Iraqis bodycounts. There are some tough questions about morality here. --Stephan Schulz (talk) 09:07, 9 April 2010 (UTC)

Foreign policy is not about morality, and it's not supposed to be -- it's all about advancing the interests of the nation and its people, and if this happens at the expense of some other nation, so be it. Read our Constitution, for Pete's sake -- it clearly states that the government is responsible to the American people and nobody else, it says absolutely nothing about any other nation having any rights that we're required to respect. 24.23.197.43 (talk) 04:55, 10 April 2010 (UTC)

That's a stupid, inhuman, unenlightened and counterproductive position to take. Luckily, most Americans don't share it. It's also, of course, wrong. The US constitution does not mention responsibility at all. But one of the other, even more fundamental founding documents states "We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness." Emphasis added for your benefit. --Stephan Schulz (talk) 10:01, 10 April 2010 (UTC)

Stephan Schulz, are you an American citizen? Because if not, then you have no say regarding American foreign policy and cannot speak for "most Americans" (oh, you have every 1st Amendment right to bitch about it all you want, but if you're not an American citizen, then nobody here cares what you think). BTW, the Rassmussen polls (and a bunch of other polls too) indicate that the majority of American citizens favor putting their own country first in international matters. 24.23.197.43 (talk) 01:31, 11 April 2010 (UTC)

Early Earth

Suppose I had a time machine and went back 100 million years on some continent. If I brought a sturdy tent, camping tools, minimal food and water to last a month and a couple of rifles and shotguns, do you think I would survive a month? --Reticuli88 (talk) 14:37, 6 April 2010 (UTC)

• That would put you in the age of dinosaurs. Back then, the air was breathable, although somewhat higher in oxygen, I think. The water in rivers and lakes should also be drinkable. Food might be a bit of an issue, as none of the food we've bred for our consumption yet existed, and I think that was even before flowering plants, which provide much of our current diet. I suppose you could shoot small dinos for food, until you ran out of ammo. You'd also need some type of shelter than would keep you safe while you slept. A tent wouldn't do it. If you could find an empty cave, then you'd only have to defend one side, and perhaps you could rig alarm bells to ring if anything entered. Shotguns and rifles might not kill an attacking dino quickly enough, so something more like a bazooka might be in order. Or, a flamethrower might work. It wouldn't kill quickly, but might be weird enough that it would make a dino back off. Also, to protect against ambush predators, you might want a mask with eyes on the back of your head. This is a technique they use in India to protect against tiger attacks. One other thing to worry about would be disease. You would probably carry back many diseases that the dinos would have no defense against, so they would die off like flies. They might also have some disease which no longer exists and which you have no defense against. So, you'd probably want to wear a full anti-contamination isolation suit. StuRat (talk) 14:48, 6 April 2010 (UTC)

• Just FYI, flowering plants have fossil evidence going back 140 million years. So they would exist, and if you brought back your own flowering plants (time travel paradoxes be damned) there would be pollinators available to keep them alive and reproducing (assuming the pollinators recognized them as potential targets for feeding; pollinators and flowers evolved hand in hand, so 100 million year old pollinators might not recognize your plants). As you noted, agricultural crops generally would not exist in a usable form, so you'd have to fall back on the hunter/gatherer diet of fruit, nuts and berries supplemented with meat from hunting. —ShadowRanger ^(talk|stalk) 15:40, 6 April 2010 (UTC)

• If you are stupid enough to carry several guns (how many to you plan shooting at any one time?) but no ammunition, probably not. Apart from that, possibly. 100 million years ago the atmosphere had about 30% oxygen - safe to breathe, but fire will be a much higher risk. CO₂ was probably 3-10 times more prevalent than today, but still a factor of 10 below where you would expect direct physiological effects. Avoid T-Rex and don't catch a fungal infection, I'd suggest. --Stephan Schulz (talk) 14:57, 6 April 2010 (UTC)

Interesting Stephan...what would happen bullet-wise if you shot a gun in 30% oxygen/different oxygen setups? Would it catch fire/have adverse affects? any idea? In terms of 'food' if you killed a pig size animal you could theoretically live on its meat for quite a number of months, assuming you can cook and store it in a way that it won't go off and make you ill. 194.221.133.226 (talk) 15:33, 6 April 2010 (UTC)

Perhaps the lubricating oil on the gun might catch fire. As for storing food so it won't spoil, how would they do that ? StuRat (talk) 15:50, 6 April 2010 (UTC)

Salt. However, I think we're missing the point here. OP seems to be bringing "food and water to last a month" with him.Rimush (talk) 15:53, 6 April 2010 (UTC)

"her" --Reticuli88 (talk) 15:59, 6 April 2010 (UTC)

(ec)Or using a smoker. Beyond that, the original poster was only interested in living there for a month and returning, not living off the land. She could arrive with a few cases of granola bars, beef jerky and vitamin pills and bypass the need for food acquisition. I think she mostly wanted to know whether a well-equipped, well-prepared human could survive the hazards of the time without excessive measures like breather masks or environmental suits. —ShadowRanger ^(talk|stalk) 15:56, 6 April 2010 (UTC)

They said "minimal food and water", so I took that to mean just enough for emergencies. Also, would they bring bags of salt with them, or mine them once there ? StuRat (talk) 15:57, 6 April 2010 (UTC)

Actually, they said "minimal food and water to last a month". I take that to mean "the minimum amount of food and water to last a month", since any other interpretation is too subjective to be useful. —ShadowRanger ^(talk|stalk) 15:58, 6 April 2010 (UTC)

Great answers, thanks! I did mean to bring enough food to survive but if I wanted to snack more, I imagined I would be eating some exotic fruit or hunting small dino game. I guess the fruit would not be possible. Wouldn't there be other predators to be afraid of besides T-Rexes? Would there be any side effects of breathing 30% more oxygen? Would the sky look different to me? Would the moon look larger? Would I smell the difference in the atmosphere? --Reticuli88 (talk) 16:07, 6 April 2010 (UTC)

A similar question was discussed before here [6]. I think you'd absolutely want to bring some good vitamin suppliments along. Who knows what important nutrients are missing in dinosaur meat.APL (talk) 16:30, 6 April 2010 (UTC)

As I noted earlier, fruit might exist (flowering plants and fruit frequently occur hand in hand). Of course, you'd have to figure out if it was poisonous or not. There would be numerous predators to deal with, though technically, no T-Rexes (they existed only for a few million years immediately preceding the extinction, not 100 million years ago). You'd probably be a bit light headed for a little while on arrival, but the increased oxygen is within human adaptive tolerances (oxygen toxicity of any sort doesn't seem to kick in until the atmosphere is 50% oxygen, and I believe it tops out around 30% historically). You wouldn't "smell" the difference in the atmospheric composition as far as the excess oxygen goes, though obviously smells produced by now extinct flora and fauna would likely be different. The increase oxygenation would speed decomposition too, so rotting material would smell more intensely, but stick around for shorter periods. Can't say what the sky or Moon would look like; technically, I believe the Moon was a little closer, but I doubt it would be particularly noticeable. —ShadowRanger ^(talk|stalk) 16:23, 6 April 2010 (UTC)

Just a note; many modern "dangerous" animals are more scared of humans (and consequently more dangerous) due to evolutionary pressures (to wit; we killed and ate the ones that weren't afraid of us). While there were more predators in the period described, you'd probably be safe around the herbivores; they wouldn't know enough to consider you a threat. The predators might be a problem, but they wouldn't have any particular experience or instinct for dealing with humans; simple traps and your weapons would likely encourage them to seek easier prey. —ShadowRanger ^(talk|stalk) 16:28, 6 April 2010 (UTC)

I would think you might tend to hyperventilate, when you exerted yourself, in an atmosphere with more oxygen and carbon dioxide. There were lots of other predators, like velociraptors, although those didn't actually appear until 75 million years ago. Actually, even if it was around, a T-Rex might ignore you, if something bigger was on the menu. BTW, the giant insects might be an annoyance. The days would also be noticeably shorter. StuRat (talk) 16:33, 6 April 2010 (UTC)

Velociraptors, were the size of a modern day chicken - really not that much to worry about! (That goddamn Jurassic Park movie has a lot to answer for!) It seems possible that T-Rex was only a scavenger - although this is a controversial view - maybe not too much to be concerned about? SteveBaker (talk) 03:11, 7 April 2010 (UTC)

Don't forget to bring a supply of antibiotic pills, and you might as well start taking them immediately; there are presumably trillions of nasty germs that'll land on you from which you have no immunity, because they've died out by 2010. I don't have it at hand, but GURPS Time Travel is an RPG sourcebook that has lots of good information like this for the practical time traveler. One sidebar helpfully tells the reader: Stop reading the rest of this book for a minute, and memorize this formula, just in case you are sent way back in time at some point in your life: 75% saltpeter, 15% charcoal, and 10% sulfur. Comet Tuttle (talk) 18:17, 6 April 2010 (UTC)

So, where do you find saltpeter? Memorizing the formula is only useful if you're in a well-labeled chemical supply closet. You need to be able to locate and identify natural sources, understand how to process them, and have enough general understanding to improvise substitutes if necessary. Nothing short of a solid understanding of chemistry and physics is sufficient to really re-manufacture modern conveniences - there's not simply "one formula to memorize". Nimur (talk) 21:15, 6 April 2010 (UTC)

Nimur, I can see you are not exhibiting that "can-do" attitude that will allow you to adequately exploit your futuristic knowledge when you get catapulted back a thousand years. See Lord Kalvan of Otherwhen — and, in fact, the main character is a (part-time, I think) reference librarian, just like you and me. Here's one link about naturally occurring saltpeter and speculation on how it was processed, and the quality of early black powder. Comet Tuttle (talk) 23:01, 6 April 2010 (UTC)

Another good book to read, of course, is The Mysterious Island by Jules Verne. In it you can learn such useful skills as smelting iron from ore and making nitroglycerin from seal blubber, even if you're stranded on a strange island with nothing but the remains of a hot-air balloon and the glass face of a watch. Of course, you may have to adapt the nitroglycerin recipe; I don't think you're too likely to find seals 100 million years ago. —Bkell (talk) 02:54, 7 April 2010 (UTC)

A good precaution, but I'm not sure how problematic it would be in practice. The mammals of the time are so different from modern day humans that it would be a fairly uncommon disease that would pose a risk to you, and saurian diseases that can affect mammals are even less common. Granted, if you stay there too long, the germs you carry with you might have time to exchange genes with the local germs and "teach" the local germs how to interact with your biology, but I would think the biggest threats would be from pathogens that don't rely on adaptations to individual species' biology. For example, virtually no virus, and only extremely rare bacteria and monocellular parasites would pose a threat. Fungi and multicellular parasites would be much more likely to cause problems. —ShadowRanger ^(talk|stalk) 18:26, 6 April 2010 (UTC)

Just as an aside, it is possible to survive almost anywhere for a month, if you import enough provisions. Antarctica, the middle of the ocean, outer space... the real question is whether one would be able to survive for an indeterminate period of time (a condition which would force one to integrate oneself into the environment). that's a much more difficult task to accomplish. --Ludwigs2 18:52, 6 April 2010 (UTC)

Stu you wouldn't need a shoulder launcher missile weapon to deal with dinosaurs that could fit inside a cave. I think an M14 rifle would be of sufficient calibre to deal with them. For handling the larger dinosaurs you can use an RPO. A flamethrower would require insanely close range and run through ammunition ridiculously fast. An M107CQ carbine firing .50 BMG would be anotehr excellent weapon to bring with you if you could. So those three weapons in that order of preference would be my choice. Rather than sleeping in a cave, as caves are hard to find are chock full of poisonous spiders and snakes, I think a lined hole in the ground with overhead cover would be preferable.--92.251.159.250 (talk) 23:03, 6 April 2010 (UTC)

The flamethrower would also be useful for swarms of small predators. Most predators would back off with one blast from it, you wouldn't need to actually hit them. They would think: "that thing is dangerous, I'm outta here". StuRat (talk) 01:34, 7 April 2010 (UTC)

An Abrams tank might be useful. It could tow the trailer with fuel and supplies. I expect T-Rex tastes a bit like chicken. Edison (talk) 23:21, 6 April 2010 (UTC)

Meh if you want to use something like that use an M1128 MGS. It's basically an APC with a tank gun on top, and 3 machine guns of various calibres attached to different spots. You could sleep inside and also carry provisions in the vehicle itself so you wouldn't have to risk yourself outside. I don't think we're allowed to bring vehicles however.--92.251.159.250 (talk) 23:36, 6 April 2010 (UTC)

As to the Moon, see Orbit of the Moon#Tidal evolution and Tidal acceleration. The Moon is currently receding by 38 mm/year, but the average rate over the last 620,000,000 years was only about 22 mm/year. So in the last 100,000,000 years it must have receded by somewhere between 2,200 and 3,800 km. It would look maybe 1% larger: as stated above, not enough to notice. The day would also be about 20 minutes shorter than now.

On the other hand, the proper motion of many of the stars over 100,000,000 years would be plenty noticeable. If you know what the constellations look like today, and had an opportunity to see the night sky without being eaten first, you would find the differences obvious; I suspect you would not find any recognizable constellations at all. And even if you did, you would also find the axis of the Earth pointing in a different direction due to axial precession (well, probably different; it might have rotated by an integer number of times and returned to the same place, just by chance). So if there was a pole star like Polaris today, it would be a different star for that reason. --Anonymous, 23:34 UTC, April 6, 2010.

If you were on the Earth either 100 million years ago or 100 thousand years ago, if you were in an area teaming with a lot of life, I think your senses would be bombarded with stimulation more so than most people generally experience today. Smells, sights and sounds would be a presence that we would only experience today if we planted ourselves amidst some large and largely undisturbed-by-mankind plot on the planet. Human activity, I think, has suppressed the imposition that all other forms of life would have on us. Bus stop (talk) 03:03, 7 April 2010 (UTC)

I think the biggest problem is likely to be food (unless you bring enough with you). We have no clue whether dinosaur meat would be edible - after all, there are plenty of reptiles with poisonous flesh. I'd want to try to find a crocodilian of some kind to hunt - although 100 million years ago is a bit far back and you'd be looking for proto-crocodilians (Crurotarsi). But those creatures appear to have changed relatively little over the intervening time - and since we know that Alligator meat is very edible (rather delicious, actually), that would be your best bet. You might also want to hunt and eat mammals of that period - again, on the grounds that there are few (if any?) present day mammals with poisonous flesh. Fruit and veg would be available - but again, how do you know what you can and can't eat? Roots and nuts have similar problems. You could certainly start taking chances on strange foods if you got desperate - but it's a hard risk to assess. Hiding out from large carnivores might not be so hard - the ratio of carnivores to herbivores tends to be fairly constant over time - and you can certainly live for a long time in the wilds of modern day Earth without having problems with them. I also suspect that you'd have little problem with bacterial/viral diseases. Most diseases don't cross species very well - and nothing back then is evolved to infect humans. Fungal problems might be a bigger issue - but if you can keep your feet dry and body clean - and take care to dress open wounds properly - you ought to be able to fend off that kind of attack for a month. Water is just water - I don't see any special problems there either. Overall, I think that anyone who could survive a month somewhere out in the wilds of modern earth would have little additional problems 100 million years ago. Just don't lose the spare batteries for your time machine...that might be bad! SteveBaker (talk) 03:07, 7 April 2010 (UTC)

If you were forced to try the local foods, I'd recommend some sort of methodical poison tests like described in this article [7]. (And its references.). It's far from a sure thing, but it would at least lessen the risks. APL (talk) 04:39, 7 April 2010 (UTC)

@Steve Baker - okay, so there are reptiles with poisonous flesh. But you're talking about dinosaurs. Are there any poisonous birds? --Polysylabic Pseudonym (talk) 08:36, 7 April 2010 (UTC)

Hooded Pitohui. --Sean 15:20, 7 April 2010 (UTC)

Dinosaurs are not birds. A small sub-group of them evolved into modern birds. But a lot of them were much more like modern reptiles than modern birds. APL (talk) 16:17, 7 April 2010 (UTC)

But they are all genetically closer to us than all current birds or reptiles. I think the chances are very good that nearly all dino-meat is going to be edible, just as nearly all bird-meat is. --Stephan Schulz (talk) 16:21, 7 April 2010 (UTC)

The seeds of the ginkgo biloba are edible, but bitter-tasting. ~AH1^(TCU) 03:41, 10 April 2010 (UTC)

Poles on a DC Motor

There seems to be many different types of DC Motors. Each has a different way/pattern to how the external poles are arranged. As the DC Motor ages the markings tend to disappear as does the manufacturers data plate. This condition leaves a DC motor without markings or data plate from which to identify the DC Motor. I have a very old possibly 1971 DC Motor in a old golf cart now used for pleasure as a Low-Speed_Vehicle(LSV)licensed for the streets. The wiring is in question and I want to know how I can know with certainty which DC Motor pole is used for what? How can I check the motor to make certain it is good? Thank You Norman pickett (talk) 15:22, 6 April 2010 (UTC)

Well, the obvious answer is to hook the positive and negative leads up one way, see if it works, and, if not, try the other way. Some motors will go backwards when hooked up at the reverse polarity. Others will do nothing. Are you afraid that hooking it up backwards could damage it ? StuRat (talk) 15:54, 6 April 2010 (UTC)

The plate on the motor may be illegible, but have you tried Googling on all the information you have on the cart (like make, model, chassis number etc.) There are a lot of cart fanatics out there with wiring diagrams. There are also a lot of amps that can melt things if you get it wrong. A meter should be able to identify which field winding is which. The poles to the commutator would (I imagine) cause the meter to flicker unsteadily as you turned the rotor by hand. The good thing is that at a 1970s machine is unlikely to have any fancy electronic control circuits. On the bad side: it is sacrilege to use a golf cart for anything but the proper purpose and you may find a thunderbolt strikes you down the first time you take it out for a spin.--Aspro (talk) 16:50, 6 April 2010 (UTC)

Flaming globes of Sigmund - dreaming phenomenon

Often, a person awakening from a dream retains the memory of a striking sentence or phrase which impressed the dreamer as funny, profound, or otherwise significant. However, on later inspection, the phrase proves meaningless or absurd. The phenomenon is illustrated in the Seinfeld episode "The Heart Attack", in which Jerry awakens chuckling, scribbles "flaming globes of Sigmund" on a scrap of paper, and goes back to sleep convinced that he has composed a joke. In Jerry's case, he cannot remember the actual meaning of his scribblings the next day, though he retains a vague sense that they were important. In my case, I often awaken with a memory of specific words, which seem, in the immediate aftermath of awakening, to retain their meaning, only to lose it gradually as the morning wears on. The words remain, but the sense of meaning dissolves. Is there a scientific term for this kind of phenomenon? How prevalent is it? Has it been the subject of any notable research? LANTZY^TALK 16:40, 6 April 2010 (UTC)

I attribute that to us thinking something is profound in a dream state, but, once we regain our ability to think logically, we know it's just gibberish. Something similar happens to people on some drugs and alcohol: They think they are having profound thoughts, but, if they record them, they later realize they were total crap, once they sober up. StuRat (talk) 16:58, 6 April 2010 (UTC)

You may find a couple of our articles helpful. Take a look at Oneirology and Dream. 10draftsdeep (talk) 18:33, 6 April 2010 (UTC)

The term I've seen used is "dream amnesia" -- things that happen in dreams make it into short term memory but aren't consolidated into long term memory unless they receive attention shortly after awakening. The sense of familiarity is probably related to the tip of the tongue effect, and perhaps to Déjà vu. Looie496 (talk) 23:48, 6 April 2010 (UTC)

The article Psychedelic experience sheds some light on perceived importance in dreams, e.g. "Level 2" where "Vast increase in abstract thought becomes apparent as the natural brain filter is bypassed". Cuddlyable3 (talk) 18:30, 9 April 2010 (UTC)

Thymus vulgaris

Is Thymus vulgaris an annual? Googlemeister (talk) 18:30, 6 April 2010 (UTC)

This site [8] says it's an evergreen. I've never been able to grow it more than about 2 years though. By the way, the picture in our article looks more like Rosemary (Rosmarinus officinalis) to me. --TammyMoet (talk) 18:42, 6 April 2010 (UTC)

I would call it (or WP calls it ) a Subshrub; err... so No I don't think so as it survives the winter. --Aspro (talk) 18:44, 6 April 2010 (UTC)

Did you read the article you linked to? It seems to contradict you - the second paragraph says the woody stem overwinters. --Tango (talk) 01:32, 7 April 2010 (UTC)

This site calls it a perennial: [9]. StuRat (talk) 18:47, 6 April 2010 (UTC)

Yes it grows for many years and can layer new roots with new growth resulting. Graeme Bartlett (talk) 08:46, 7 April 2010 (UTC)

Another factoid for discussion...

'Whenever it has been established that a bird possesses the ability to count, it can usually only count up to as far as the number of eggs typically laid by its species per clutch, plus one'. I suppose that the wisdom behind this being that the only real use a bird has for counting objects is to determine if am egg has been taken or if nest parasite or another member of its species has laid an extra egg in its nest. Confirm/debunk?

I'm trying to tie this in to something my grandmother once told me about a chicken's ability to count as related to the number of 'foreign' (i.e. from another hen, or a duck - as is/was done 'down on the farm') eggs that can safely be placed in with her clutch without her freaking out. It was something along the lines of 'she only counts the first seven, so if she already has seven eggs, you can add more and she won't notice - but if she has six and you add a seventh, she'll abandon the whole lot or start destroying eggs' - but I may be remembering that wrong (long time ago now). --Kurt Shaped Box (talk) 18:48, 6 April 2010 (UTC)

Our article Bird intelligence claims some birds have been shown to be able to count up to 3, 6, or possibly 8. It warns birds may be subitizing and not truly counting. Comet Tuttle (talk) 19:31, 6 April 2010 (UTC)

This statement sounds a lot like the premise behind rabbit math in the novel Watership Down. The main character's name is "Hrairoo", which is translated into English as "Fiver"; he was some number past 4 in his litter, and rabbits can only count up to 4; all numbers past that are "Hrair", which means "more than 4". --Jayron32 20:20, 6 April 2010 (UTC)

I'd say that most birds also cannot recognize the eggs of other species of birds from their own. See brood parasite. ~AH1^(TCU) 03:38, 10 April 2010 (UTC)

what am I doing wrong with this acid base problem? (sodium acetate solution ==> acidic pH?)

I have NO idea why I'm getting an acidic pH. I have pure sodium acetate solution and there is no external source of H+ except for water.

Firstly, this is being conducted at 80 C, so K_w is modified to 1.5 * 10^-13. Which shouldn't be too much of a hiccup.

[H+] = 1.5 * 10^-13 / [OH-]

Relying on the approximation, [OH-] = [AcOH].

so K@353K = 8 * 10^-5 = [AcO-][H+] / [AcOH] = (0.1-x) * (1.5 * 10^-13 / [x]) /  (x)
= (1.5 * 10^-14  - (1.5/x) * 10^-13) / x = 1.5x^-1 * 10^-14 – 1.5x^-2 * 10^-13 = 8 * 10^-5  
0  = 8x^2 * 10^-5  - 1.5x * 10^-14  + 1.5 * 10^-13 
0 = 5.33x^2 * 10^8 – 0.1x + 1  
5.33x^2 * 10^8 = 0.1x – 1 (the last term is negligible) 
5.33 * 10^8 x = 0.1
0.1 / (5.33 * 10^8) = x =  1.876 * 10^-10  = [OH-] 
pOH = 9.7267 
pH = 12.824 – pOH = 3.097 

The 353K water makes it slightly more acidic, but I should still get an alkaline solution, right?

John Riemann Soong (talk) 21:53, 6 April 2010 (UTC)

It would help if you annotated your equations. I'm not sure exactly (it's been a while since I did this) but your issue might be that you set up the equation wrong initially. The sodium(Na+) and the acetate (AcO-) presumably dissociate completely leaving whatever your molar concentration is of acetate in solution. The acetate, being a weak acid, starts grubbing for protons from the water and establishes an equilibrium between acetate (AcO-) and acetic acid (AcOH) and OH-. I think your equation should be set up with AcOH and OH- on the top and AcO- and H₂O on the bottom. The pKb of acetate from sodium acetate is 9.25 btw. Hope someone will correct me if I am wrong... 152.16.15.144 (talk) 22:30, 6 April 2010 (UTC)

Well I kind of solved it a different way. (As in I found a correct answer another way.) But I'm using K_a, so I just modified the expression to use K_a. I defined H+ in terms OH-, and worked from there... I wonder why it doesn't work ... John Riemann Soong (talk) 23:46, 6 April 2010 (UTC)

do the effects of smoking ever go away? (smoking regular cigarettes like marlboros)

1. do the effects of smoking ever go away?
specifically, you see pictures of healthy nonsmoker's as contrasted with all charred up smoker's lungs; if somebody stops smoking (say, after 5-6 years of smoking from 19-25), then presumably their lungs are between the two. Would they get back to totally healthy after a number of years? Or would the blackened tar and stuff stay in their lungs for the rest of their lives?

2. besides the black tar, what other symptoms do smokers develop that might stay with them? (e.g. yellow teeth, wrinkles, and so on)

3. how much of specifically the lung effect is present for a second hand smoker? would this disappear after a number of years?

For someone who is not a smoker, but around smokers when they smoke, would the same lung effect be present? Would this disapear after a number of years if they were exclusively in nonsmoker areas?

Thank you very much. Note: I am not asking for medical advice. 82.113.106.35 (talk) 21:53, 6 April 2010 (UTC)

This site should help with your first question. I think passive smoking has the same effects as direct smoking, just reduced. How severe those effects will be will, of course, depend on the level of exposure. --Tango (talk) 22:04, 6 April 2010 (UTC)

I cannot speak about the effects to one's lungs, but studies show that the effects to one's periodontium (in terms of how smoking effects wound healing, etc. in periodontal disease, implant placement) take 11 years to become statistically insignificant. DRosenbach ^{(Talk | Contribs)} 03:53, 7 April 2010 (UTC)

The Surgeon General's report answers a couple of your questions. After about three years, the risk of heart attack falls to that of a never-smoker. It takes over 15 years of cessation for the risk of lung cancer death to fall to that of never-smokers. Axl ¤ [Talk] 07:50, 8 April 2010 (UTC)

ex=paratrooper with back problem been put on tramadol for 8 years.........

I'm sorry, but this appears to be a request for medical advice, which we cannot legally provide. Please ask your doctor for more information. —ShadowRanger ^(talk|stalk) 22:09, 6 April 2010 (UTC)

Actually, the concern is not that we "cannot legally provide" it; it is an ethical concern — what if we, anonymous people on the Internet, give you advice which you follow, and we're wrong, and your partner ends up screwing up his health more? You do need to consult a doctor about any medical advice, sorry. Comet Tuttle (talk) 22:48, 6 April 2010 (UTC)

D'oh. Mixed up medical and legal advice. Though I suppose in both cases it's primarily a matter of ethics. Thanks for the reminder. —ShadowRanger ^(talk|stalk) 15:58, 7 April 2010 (UTC)

Sodium bicarbonate

Is sodium from sodium bicarbonate (baking soda) as unhealthy as sodium from sodium chloride (salt)? --70.129.184.122 (talk) 22:12, 6 April 2010 (UTC)

Yes, insofar as when it reacts in your stomach, it produces NaCl, per this reaction diagram from the article:

NaHCO₃ + HCl → NaCl + H₂CO₃

H₂CO₃ → H₂O + CO₂(g)

The amount of sodium per gram will be less than the amount per gram of NaCl though. —ShadowRanger ^(talk|stalk) 22:15, 6 April 2010 (UTC)

Really, the Chloride doesn't matter at all: it's the Na⁺ ion that's bad for you, and the chloride's just along for the ride. Of course, baking soda does contain less sodium per mass (39% for salt vs. 27% for baking soda), and most people consume a lot less baking soda than they do salt. Buddy431 (talk) 00:00, 7 April 2010 (UTC)

However, eating elemental metallic sodium would be a very bad idea. StuRat (talk)

OUCH!!! 24.23.197.43 (talk) 01:28, 7 April 2010 (UTC)

Acid + metal reaction...very bad idea. ~AH1^(TCU) 02:59, 7 April 2010 (UTC)

Yeah, I was pretty sure it wouldn't matter, but I figured illustrating that sodium bicarbonate becomes sodium chloride in your stomach would illustrate why. In other circumstances, ingestion of a particular element won't lead to digestion and absorption if the element in question is tightly bonded or otherwise indigestible (e.g. insoluble fiber contributes nothing to your nutritional needs, it just aids movement within the digestive system). Since sodium bicarbonate has a known reaction with your stomach's hydrochloric acid, and the result is salt, there is no doubt that it will be treated identically. —ShadowRanger ^(talk|stalk) 15:50, 7 April 2010 (UTC)

Using yeast instead is not difficult, at least in a bread-machine. I sometimes add sultanas to the flour to get something cake-like. People must have made cakes with yeast before baking powder was invented. 78.149.173.243 (talk) 10:39, 7 April 2010 (UTC)

You still get sodium ions when you consume any soluble sodium salt. Sodium ions have the certain health effects (they are not necessarily bad, by the way), regardless of the anion, even though the anion may mitigate or augment the effects.--Cheminterest (talk) 20:37, 7 April 2010 (UTC)

Sodium ions per se are not harmful to human health -- indeed, they are essential for human cells to function properly. It's only when you consume too much sodium, or too much at one time, that it can become a health problem. 24.23.197.43 (talk) 05:55, 8 April 2010 (UTC)

Time and the Big Bang

Which frame of reference was chosen so that our recent estimations were considered? For instance, it took about less than 400,000 years for the decoupling event to have occurred after the Big Bang and the estimated age of the Universe is 13.75 billion years.--Email4mobile (talk) 22:32, 6 April 2010 (UTC)

I'm not sure what you're asking but it seems to me that the right answer to your question likely is the comoving frame with the galaxies. Read comoving coordinates. Dauto (talk) 02:28, 7 April 2010 (UTC)

Can I translate the phrase "comoving" as "Associated with movement"?--Email4mobile (talk) 12:19, 7 April 2010 (UTC)

It is, but that would not be helpful in the least. Click the link and read what it means. —ShadowRanger ^(talk|stalk) 12:41, 7 April 2010 (UTC)

Yes, ShadowRanger, but I would like to translate this article into Arabic wiki. In this case I've to to give it a meaningful name.--Email4mobile (talk) 16:05, 7 April 2010 (UTC)

Ouch. Defining it without resorting to incredibly drawn out language seems tricky. I have no idea what Arabic speaking scientists would use to describe it; the problem is that any attempt to translate it directly will likely lack scientific precision. I suppose for lack of another option, you might try creating an article on the closest translation for "comoving frame" you can come up with and link it from your Arabic wikipedia article (and make it clear what the English equivalent is). If a bilingual English/Arabic speaking scientist can provide the proper terminology, the article could be renamed and the terminology corrected for scientific accuracy. Sorry I can't help more; my knowledge of Arabic comes from the few untranslated words in my hundred year old copy of the Thousand Nights and One Night (as it is titled for my edition), plus the overlap of my abysmal knowledge of Hebrew (a dozen words or so) with Arabic cognates (leaving only two Arabic words). —ShadowRanger ^(talk|stalk) 16:21, 7 April 2010 (UTC)

lol, Shukran (means Thanks), ShadowRanger. Unfortunately, there is no Arabic wiki article containing the term comove yet but I will go ahead with the translation anyway. Someday an Arab scientist will give it the correct name. Have a nice time with Alf Laila wa Laila (Thousand Nights and One Night). --Email4mobile (talk) 16:51, 7 April 2010 (UTC)

In case it helps, "comoving" has the sense of "moving along with" something else, which I think is a little more specific than "associated with movement." You can think of a twig or leaf moving along with the water in a river. -- Coneslayer (talk) 16:57, 7 April 2010 (UTC)

Yes, it really isn't a complicated idea. The times (like 400,000 years) are measured by clocks that are moving with roughly the same speed as the stuff around them. These days you have to average over a pretty large area (tens or hundreds of millions of light years) to get rid of local variations in speed. The early universe was much more uniform, though, as well as much denser, and you would immediately encounter a lot of resistance if you didn't "go with the flow". An easier way to figure out the right speed in the present-day universe is to look at the cosmic microwave background, which is still very uniform (because light doesn't clump together the way atoms do). If the microwave background looks blueshifted in one direction and redshifted in the opposite direction, then you're going too fast in the blueshifted direction. -- BenRG (talk) 19:12, 7 April 2010 (UTC)

If you ever need a dozen hundred year old Arabic slang words for genitalia, I'm your man. The translators of my edition were quite prudish. :-) —ShadowRanger ^(talk|stalk) 18:44, 7 April 2010 (UTC)

Yes, Coneslayer. I went through the article and then understood it can be an alternative to "get/go along with" which has an equivalent single-word in Arabic. Thanks for all of you.--Email4mobile (talk) 18:09, 7 April 2010 (UTC)

discrepancies in attempting to isolate enthalpies/entropies of dissociation

At 293K, I am told the K_a for formic acid is 1.765 * 10^-4, but 1.768 * 10^-4 at 303K.

Using the simultaneous equations: ∆H – 293K*∆S = ∆G @ 293K = -R * 293K ln (1.765 * 10^-4) (21054 J/mol) ∆H – 303K*∆S = ∆G @ 303K = -R * 303K ln (1.768 * 10^-4) (21768 J/mol)

21054 J/mol – 21768 J/mol = -714 J/mol = (293-303)K * ∆S (714 J/mol / 10K) = 71.43 J/(mol*K) = ∆S

but, plugging back in: 21054 J/mol + 293K*71.43 (J/(mol*K)) = 41974 J/mol = ∆H and I get delta-H of 43400 J/mol at 303K. Uhhhh? John Riemann Soong (talk) 23:03, 6 April 2010 (UTC)

Try this instead. I am not sure what you did wrong, but if you reduce the simultaneous equations to a single equation, you should get

• ∆G₁ - ∆G₂ = (T₂ - T₁)∆S, or simpler
• ∆G₂₉₃ - ∆G₃₀₃ = (303-293)∆S or even simpler
• ∆G₂₉₃ - ∆G₃₀₃ = 10*∆S

I get ∆G₃₀₃ = 21756 J/mol, and ∆G₂₉₃ = 21042. Sub those in, and I get

• 21042 - 21756 = 10*∆S
• -714 = 10*∆S
• -71.4 J/molK = ∆S

Back to your initial two equations now,

• ∆G₂₉₃ = ∆H - 293*∆S
• 21042 = ∆H - 293*(-71.4)
• 21042 = ∆H - (-20920)
• 122 J/mol = ∆H

and for the other temperature

• ∆G₃₀₃ = ∆H - 303*∆S
• 21756 = ∆H - 303*(-71.4)
• 21756 = ∆H - (-21634)
• 122 J/mol = ∆H

Same answer. Near as I can tell, you dropped a - sign in your final step, so you added where you should have subtracted. BTW, I charge $40.00 per hour for this sort of tutoring, so this coupled with the amine-buffer help below would normally cost you some serious coin... --Jayron32 04:26, 7 April 2010 (UTC)

Health hazards from living near a busy road

Is there any information available about how dangerous it is to live x metres from a busy road, in terms of reduced longevity and so on? I'm thinking of the traffic fume pollution, such as the particulates and Polycyclic aromatic hydrocarbons, and how these may decline (or not) with distance from the traffic. Thanks. 92.29.111.79 (talk) 23:17, 6 April 2010 (UTC)

There are also claims that long term exposure to the noise of a busy road can have a deleterious effect. --Tango (talk) 23:21, 6 April 2010 (UTC)

A quick googl search (living near an road health) netted me these, among others: [10], [11], [12], etc. I'd say yes, there is information available, though I'm not sure you'll find a direct x meters to nearest road vs. mean lifespan graph anywhere. Buddy431 (talk) 00:54, 7 April 2010 (UTC)

There's also the possibility of being hit by a car, the stress caused by having cars whip by, and, if the road has been there a long time, an accumulation of lead and toxins in the soil near the road, which is a problem if food is grown there. StuRat (talk) 00:59, 7 April 2010 (UTC)

See also noise pollution. ~AH1^(TCU) 02:52, 7 April 2010 (UTC)

Try this article. It has quite detailed information, and is not entirely intuitive. If you would like my interpretation of it, please ask. Axl ¤ [Talk] 22:05, 7 April 2010 (UTC)

Thanks. "For an increase in traffic intensity of 10,000 motor vehicles in 24 hours (motor vehicles/day) on the road nearest a subject's residence, the RR was 1.03 (95% CI, 1.00-1.08) for natural-cause mortality, 1.05 (0.99-1.12) for cardiovascular mortality, 1.10 (0.95-1.26) for respiratory mortality, 1.07 (0.96-1.19) for lung cancer mortality, and 1.00 (0.94-1.06) for noncardiopulmonary, non-lung cancer mortality. " Does the RR of 1.03 mean a 3% increase in mortality? Is it possible to esimate the reduced average longevitry please? 92.29.42.231 (talk) 10:15, 8 April 2010 (UTC)

" Does the RR of 1.03 mean a 3% increase in mortality? "

Yes.

" Is it possible to estimate the reduced average longevity please? "

There is a rather complex relationship between mortality rate and life expectancy. This website gives a nice summary. The article doesn't give enough infomation to calculate life expectancy. It took me quite a bit of digging around to find an estimate for life expectancy. This report from the Committee on the Medical Effects of Air Pollution, page 6, states "Estimate of effect in time-series studies based on a 1 microg/m³ reduction in annual mean PM₁₀ assuming a coefficient of 0.075%, a loss of life expectancy of 2 to 6 months per death brought forward and a similar effect on all ages."

Axl ¤ [Talk] 09:41, 10 April 2010 (UTC)

calculating the %protonation of amine in an ammonium acetate like salt...

I have 0.32M formic acid solution (K_a = 1.765 * 10^-4). I then add 0.2 equivalents sodium hydroxide. I then add 0.32M of an amine (K_b = 8 * 10^-3).

How do I calculate the %protonation of the amine?

My current work: The 0.32M formic acid solution + 0.2 equiv NaOH is calculated to have pH 3.3156. A- / AH = 0.2529; e.g. there is 0.06459 M formate anions and 0.2554 M formic acid.

Ka for formic acid = [H+][HCOO-] / [HCOOH]

Kb for amine = [OH-][RNH3+] / [RNH2]

Ka_acid * Kb_amine = Kw [HCOO-][RNH3+] / [RNH2][HCOOH]

Now I'm stuck. John Riemann Soong (talk) 23:44, 6 April 2010 (UTC)

Back up a bit. The formic acid/NaOH is just a buffer; I assume you used the Henderson-Hasselbalch equation to calculate the pH. At that pH, pOH = 14-3.3156 = 10.6048, so [OH-] = 10^-pOH = 2.48 * 10^-11.

	RNH2	+	H2O	-->	RNH3+	+	OH-
INITIAL	0.32		Ignore		0		2.48 * 10^-11
CHANGE	- x		Ignore		+ x		+ x
EQUILIBRIUM	0.32 - x		Ignore		x		2.48 * 10^-11 + x

Now, use the equation Kb = [RNH3+]*[OH-]/[RNH2], and subbing from the bottom line of the above table, you get 8 * 10^-3 = (x)*(2.48 * 10^-11 + x)/(0.32 - x). Solve for x. Plug the x value back into the bottom line of the above table to find the equilbrium concentrations of [RNH2] and [RNH3+], and % protonation is simply ratio of the equilibrium concentrations * 100, or [RNH3+]/[RNH2] * 100. I hope that made sense. This is much easier to teach when talking to someone in person... --Jayron32 03:57, 7 April 2010 (UTC)

April 7

Radio station reception

I'm not sure if this falls under technology or electronics, but if it is the latter, feel free to move this to the computing desk. One of my favorite radio stations is KFDI-FM out of Wichita, Kansas. Unfortunatly, I live in the vicinity of Salina, Kansas. This map shows the reception range of KFDI (at the range where Salina is, the reception could be classified as spotty at best). Here are the technical specifications of the station. What steps can I take to get better reception, perhaps by modifying a radio? Would a Broadcast relay station be a feasible step on the part of either the radio station or myself, considering that would allow this radio station to tap into an additional 55,000 people for it's market? In short, what ways (other than their online stream) could I attain reception of this station in Salina? Ks0stm ^(T•C•G) 01:06, 7 April 2010 (UTC)

A bigger, better, higher, directional antenna is the obvious answer. What type of antenna do you have now ? StuRat (talk) 01:03, 7 April 2010 (UTC)

I'm thinking of the type found on a vehicle so that I can get reception while driving. Ks0stm ^(T•C•G) 01:06, 7 April 2010 (UTC)

That isn't going to work, as you can't mount much of an antenna to a car. So, a rebroadcast relay station might be your only option. You could put a big antenna at your house, then rebroadcast from there, but you'd have to get the station and the FCC to agree, and good luck with that. StuRat (talk) 01:11, 7 April 2010 (UTC)

Also, that range map is rather iffy. The range is not usually completely circular like that. The two primary reasons are local geography, such as hills, and the signal being somewhat direction, when broadcast. StuRat (talk) 01:11, 7 April 2010 (UTC)

You say the range is not perfectly circular because of hills… Have you been to central Kansas? :-) —Bkell (talk) 02:48, 7 April 2010 (UTC)

I should also back up and ask why this station is so important ? Is there a particular program you just love ? Maybe there's some other way to access it. StuRat (talk) 01:13, 7 April 2010 (UTC)

The news and severe weather coverage is unparalleled, and for a severe weather fanatic like me, this makes the station very appealing. I like to monitor the station when there is severe weather to the South or southwest that may move towards Salina. Unfortunately, this is one of the times/situations it decides to offer its most spotty reception. Ks0stm ^(T•C•G) 02:05, 7 April 2010 (UTC)

Perhaps a weather radio would be in order ? StuRat (talk) 02:10, 7 April 2010 (UTC)

For news, perhaps the local NPR station, KHCD-FM, 89.5, might do. They aren't 24-hour news, but have frequent news, including in-depth stories. StuRat (talk) 02:20, 7 April 2010 (UTC)

This is probably not a practical option. But they have an option to listen on their web-site. What's the G3 covereage like in your area? You could theoretically listen on a mobile internet device like an iPhone.

(Be very carefull about monthly bandwidth caps and overage fees before trying this!) APL (talk) 04:18, 7 April 2010 (UTC)

A better antenna would be a good option. FM radio uses approximately the same frequency as VHF TV. So any good VHF (not UHF) TV antenna would also work for FM. In fact you may have a TV antenna on your roof already, and with a splitter you can get FM from it as well. There are a LOT of different kinds of antennas. I'm certain with a good antenna you could receive your station. A car would be tough, but even there you might be able to do something. For example a whip antenna tuned to exactly the frequency of your chosen station. After that any improvements (other than height) will also cause your antenna to become directional (to a greater or lesser extent depending on the antenna design). This may be tough in a car. The more directional the antenna the weaker a station you can receive, but also the harder it is to position it exactly right (plus it won't get other stations). Ariel. (talk) 05:47, 7 April 2010 (UTC)

acid rain/ fog

wouldn't fog contain more acid/impurities than rain? because its more concentrated/ has less water in it ?

Fog is not necessarily "more concentrated" than rain, it just contains smaller size droplets (which are therefore suspended in the air and don't fall to the ground). As for the amount of water, both of these form when humidity reaches saturation level, so the amount of water is the same. FWiW 24.23.197.43 (talk) 01:34, 7 April 2010 (UTC)

Fog is basically a ground-level cloud. Since rain comes from clouds - it's hard to imagine how there would be any difference in the impurity level. I suppose it's possible that rain might pick up impurities as it falls - but then we'd have to ask what the past history of cloud was. If there is a general answer, I'd guess that they would be about the same. SteveBaker (talk) 02:40, 7 April 2010 (UTC)

Acids in rain that cause acid rain usually forms dissolved compounds in the droplets such as nitric acid and carbonic acid. Impurities, or particulate matter, often forms condensation nuclei in the cloud. Since fog or cloud droplets are usually smaller than raindrops, as rain is the combination of many smaller droplets from condensation, it's possible that the minute amounts of acid or particulates in the droplets could combine and add up. However, according to acid rain, "Occasional pH readings in rain and fog water of well below 2.4 have been reported in industrialized areas" (acid fog is a red link). ~AH1^(TCU) 02:46, 7 April 2010 (UTC)

Acid fog is usually referred to as a Pea soup fog and becomes so because the fog is trapped in an Inversion layer, hence giving it time to soak up combustion products. Rain can get very polluted when caused by such instances as the bombing of Hiroshima (black rain) or rain from the ash column of an erupting volcano. The volcanic rain may well contain hydrofluoric acid, which can dissolve glass. They both should have the same load carrying capacity as the other, all things being equal. --Aspro (talk) 09:50, 7 April 2010 (UTC)

A Pea soup fog is a thick fog. Acid fog is acidic fog, it needn't be thick. Pea soupers may, however, have been acidic, but one is not necessarily the other. --Polysylabic Pseudonym (talk) 08:39, 9 April 2010 (UTC)

Salt Level in water to corrode metal

Hi Friend,

can you help me with this?

i am constructing a recycling water system for washing vehicle.

i need to know the dissolved salt level in the water that will corrode metal.

example: maybe 2000ppm and above will corrode metal.

so i will discharge all water and replace them before reaching 2000 ppm.

please assist.

Alex Singapore —Preceding unsigned comment added by Thocy (talk • contribs) 02:24, 7 April 2010 (UTC)

Salt corrodes iron by promoting ion exchange and redox reactions between the iron and the air/water. Therefore, any amount of any salt in the water will tend to accelerate corrosion to some extent. That said, the rate of corrosion is directly related to the concentration of salt in the water -- sea water will corrode iron pretty quickly, while tap water will cause only a negligible amount of corrosion (in the short run anyway). In short, there's no hard and fast threshold above which salt will corrode iron; the main rule to remember is, the less salt the better. FWiW 24.23.197.43 (talk) 02:37, 7 April 2010 (UTC)

Water will corrode iron even without any salt. Make your pipes out of a different metal. Aluminum if you can, but it's probably hard to get pipes. Copper is probably your best bet, it resists corrosion even with seawater, and it's easy to buy. Copper pipes come (in the US) in three different thicknesses, K, L, M. K is thickest, and you way want to spend a little extra and use it instead of a thinner one. You can also use plastic, PEX is a good choice for high temperature applications, also CPVC (not regular PVC). Ariel. (talk) 05:03, 7 April 2010 (UTC)

You can also protect your iron pipes via Cathodic protection, usually by using coated iron pipes; i.e. iron coated with aluminum, magnesium, or zinc, such that the more active metal is sacrificially corroded, protecting the iron. The lede of the Cathodic protection article specifically mentions protecting iron pipes as a common usage. --Jayron32 05:08, 7 April 2010 (UTC)

But this is a vehicle washing system - isn't the problem to protect the vehicles rather than the washing equipment?!? You can certainly have the washer use plastic pipes - but if someone brings their car to be washed, the last thing they want is salty water squirted up into places where water wouldn't ordinarily go! When the roads have been de-iced with salt, I take my car to the car wash to wash the salt off. If the car wash recycles its water then after a few dozen cars have been through it, they'll be worse off than if they hadn't been washed in the first place! SteveBaker (talk) 20:14, 7 April 2010 (UTC)

“But this is a vehicle washing system - isn't the problem to protect the vehicles rather than the washing equipment?!?”. Why would someone who purports to be from Singapore be interested in protecting YOUR auto-mobile? Does the company ‘you’ work for really put the preservation of customers assets before its own? So why should Alex? --Aspro (talk) 20:54, 7 April 2010 (UTC)

The question was a very reasonable one, about a salinity limit for the makeup water system to be held to at a car wash, and I understood the limit to be for avoiding excess rust of the cars. Does anyone have referenced data to respond to it, as to industry practice? Edison (talk) 21:43, 7 April 2010 (UTC)

Here is an interesting site describing how a system which washes salt trucks (good recipe for getting salty water in the drain) did not just dump the salty water into the wewer to harm the environment, but used filtration including reverse osmosis to get the salinity of the discharged water down to 1/20 that of the tap water. Clearly a less ambitious setup could get it down to the same as the starting level in tap water. [13] under "salinity" says it is not recommended to set some safe salinity level to prevent corrosion (for reason a chemist might understand). Edison (talk) 22:30, 7 April 2010 (UTC)

Here is a company which sells equipment to reclaim water used in carwashes, including removing salt. Their technical documents might be helpful. Edison (talk) 22:35, 7 April 2010 (UTC)

physics question

Alright I've been working on this one for such a long time, could someone please help me? Two steel balls are suspended on 1.50 meter long strings of negligible mass. The first mass is released from rest from an angle of 40.0o and collides perfectly elastically with the larger mass which was originally at rest. To what maximum angle will the larger ball rise after the collision? The answer is 26.4 degrees but im wondering what to use like conservation of energy, momentum or something else. Thanks for your help. 198.188.150.134 (talk) 07:50, 7 April 2010 (UTC)

I would use conservation of momentum. But first you will also need to calculate the velocity of the first ball when it hits the second (acceleration due to gravity). The by using conservation of momentum you know the velocity of the second ball, and then you'll need to calculate how high it will rise due to that velocity (inverse of before), and then a little trig to see what angle that makes. I'm pretty sure that doesn't make any difference that it moves in a curve, rather than straight down, so use the angles to calculate height, but otherwise ignore it. Ariel. (talk) 07:59, 7 April 2010 (UTC)

why not use conservation of energy? m1*g*r*(1-cos(40deg))=m2*g*r*(1-cos( ? deg)) gravitational potential energy 157.193.175.207 (talk) 09:03, 7 April 2010 (UTC)

edit : this is the 'maximum' height in the sense that it is the height reached if the first ball transfers all of its energy to the second ball. You probably need 2 equations (energy and momentum conservation) to figure out how the energy gets redistributed over the balls. 157.193.175.207 (talk) 09:06, 7 April 2010 (UTC)

Yes, you need to use both conservation of momentum and conservation of energy. Unless the two balls have the same mass (which we can infer they do not) then the first ball is not stationary after the collision and so does not transfer all of its energy to the second ball. Gandalf61 (talk) 12:23, 7 April 2010 (UTC)

If you want us to do numeric calcs, we'll need to know the relative masses of the two balls. StuRat (talk) 10:15, 7 April 2010 (UTC)

...or we can work backwards and infer that the first (swinging) ball has half the mass of the second (stationary) ball. Gandalf61 (talk) 12:23, 7 April 2010 (UTC)

@157 and Gandalf: you do need to use both conservation of energy and momentum, but you don't necessarily need to do it with two equations. A helpful simplification is that in an elastic collision, from the center of mass reference frame, the balls appear to be each traveling at the same speed before and after the collision. Buddy431 (talk) 13:49, 7 April 2010 (UTC)

So let's see here: I get that the first ball drops 0.35 m, and so is traveling at a speed of 2.62 m/s before the collision. The second ball reaches a height of 0.16 m, and so was traveling at a speed of 1.75 m/s after the collision. The 2nd ball was initially at rest, so we see that the center of mass must be moving at half that speed, or 0.88 m/s, during the collision. An elementary center of mass calculation shows that the second ball has twice the mass of the first. Buddy431 (talk) 13:49, 7 April 2010 (UTC)

Changes in cooking oil

I have put this on the science desk because it seems to be a science based problem. I have been cooking in sunflower oil in a small electric fryer. The fryer and the basket is now soiled with a kind of adherent waxy/rubbery substance which is clearly altered oil. It is on the areas of the fryer which are open to the air, that is, it is not below the level of the oil, just the lid, basket and handle. What type of substance is this? How can I clean the fryer because it seems to be impervious to detergents and caustic dish-washing products. Caesar's Daddy (talk) 09:27, 7 April 2010 (UTC)

It is the oil that has under gone Polymerization. Is the vessel stainless steel , aluminium or glass etc.,--Aspro (talk) 09:55, 7 April 2010 (UTC)

The main part is Teflonned aluminium, others are plastic. Caesar's Daddy (talk) 10:06, 7 April 2010 (UTC)

I was going to suggest steel wool, but it sounds rather delicate, and would be scratched by anything that would clean it, so I think you're just going to have to live with it. StuRat (talk) 10:10, 7 April 2010 (UTC)

Try very hot water with laundry detergent and a stiff toothbrush. As the construction involves aluminium avoid caustic soda, which would otherwise have been my suggestion. DuncanHill (talk) 10:18, 7 April 2010 (UTC)

Teflonned aluminium! Oh dear. Personally, I would never fry in Teflon cookware do to the toxic by products caused by heat -so throw it away.[14] Also, the cooking oil industry has spent billions persuading both the public and the medical industry that saturated fats are bad, despite the fact that the healthy liver produces them. For frying in future, and to avoid this rubbery gummy stuff, use hard fats like coconut, palm, or if your not kosher, ghee or lard. They are the best. These also have the advantage of being able to cook at higher temperatures without burning. Also, change fat frequently, to avoid a build up of acrylamide. If the teflon coating is in good condition then you could risk applying some soda crystals which is less caustic. The liquid version that comes in a squirt bottle is easiest to use as it is just the right consistency. Coat liberally and leave over-night. Next morning remove as much of the softened rubbery gum as possible. Apply some more soda and leave again. Main ingredient required is ‘patience.’ The Teflon coating should protect the aluminium beneath. --Aspro (talk) 10:57, 7 April 2010 (UTC)

Toxic products due to high temperature teflon is not so true. By the time you reach a high enough temperature to release anything toxic, oil would have released massive amounts of smoke, or even caught fire. In other words, you never get the teflon that hot. Ariel. (talk) 18:12, 7 April 2010 (UTC)

The OP seems to be talking about a deep fat frier. I don't think you can practically deep fat fry things in ghee or lard (I've never used coconut or palm oil). You would also be using enormous amounts of the stuff. I use a small amount of ghee when making curries, but I would never soak my food in the stuff, it would be a heart attack on a plate. While saturated fats are an acceptable part of your diet, they are only acceptable in small amounts. --Tango (talk) 14:38, 7 April 2010 (UTC)

Fish and chip shops across the North of England use beef dripping to fry their food. The taste is far better (in many people's opinion, including mine) than frying stuff in oil. The dripping heats to a higher temperature, which instantly seals the food, and reduces absorption of the fat by the food: in which case, it should even be healthier than frying in oil. [15] Don't whatever you do use palm oil: you will render orangutans homeless! [16] Olive oil is not really suited to deep frying, being too heavy. I think you need to clean your fryer much more often than you have been! --TammyMoet (talk) 14:58, 7 April 2010 (UTC)

If you are genuinely concerned about orangutans it's surely better to use sustainable palm oil rather then try and halt development in SEA completely because you've already destroyed a significant part of your forests so wanna feel good by forcing people to preserve stuff for you at no cost. Particularly since if you don't encourage the growth of the industry, what's likely to happen is it will be sold to places like China where there's far less incentive to do anything properly and there being no similar prescription on say soyabean oil which is more inefficient to produce and could come from the Amazon (of course a big part of it goes for cattle so perhaps you don't have to worry about the oil) or say the plenty of inefficiently produced oils in the developed world (but as I said it's okay, we cut down the natural forest there a long time ago so no need to worry) P.S. Just to be clear, I'm not saying you shouldn't consider the environmental effects of your decisions but that I strongly dislike the simplistic thinking that goes into things like 'don't buy palm oil, you will render orangutans homeless'. Things are alot more complex then fit in a Greenpeace slogan unfortunately and it's all to convient to care about environmental problems in other countries where your decisions are not going to have a big effect on you or the people you know and your country and then not worry about the ones far closer to home which will affect such things. Sadly simplistic thinking leads to things like thinking of jatropha as a wonder crop, we all know how that's turned out so far [17]... Nil Einne (talk) 23:08, 7 April 2010 (UTC)

Thanks for those responses - very helpful. I think we are going to be finding an alternative to sunflower oil. We used to use olive oil which did not polymerise to such an extent but was more costly - ah well, you get what you pay for (usually). Thanks again. Caesar's Daddy (talk) 13:59, 7 April 2010 (UTC)

Try corn oil. See Smoke point for a nice list. Note that Sunflower oil has two entries in the list, and also that the smoke point is not everything, the particular type of oil matters too. I don't know which type is better/worse for frying though. If you check the articles for the particular oils you'll see a wide variety in what specific kinds of oils they are made of. Ariel. (talk) 18:12, 7 April 2010 (UTC)

I disagree with the promotion of saturated fat usage by Aspro, and suggest you read Saturated fat as to the increased health risks associated with high consumption of these fats. Edison (talk) 14:26, 7 April 2010 (UTC)

Agreed. StuRat (talk) 14:33, 7 April 2010 (UTC)

Thanks chaps, I'm not as daft as I look. [18] Caesar's Daddy (talk) 15:48, 7 April 2010 (UTC)

The questioner was not asking about a balanced diet of fats. So I can’t be accused of promoting saturated fats per se. Also, I stated clearly that the cooking oil industry has spent billions promoting their products. These sales and marketing factoids are based on theories without substantial scientific proof that diets high in saturated fats cause CVD (co-morbid smoking rates did much confuse the results and so call them into question still further). Nor have the pharmaceutical industry proven that lowing blood cholesterol reduces death in ‘real populations’, nor do they attempt to explain why population with diets very high saturated fats (like the Inuits) have enjoyed low levels of CVD (until they adopted western diets). These awkward facts are often mention in medical journals such as the BMJ. There is much nonsense written and repeated about fats and oils. Prof. Udo Erasmus has probably done the most thorough systematic review of fats and oils, if you would like to discover more. Here is his bit on frying. [19]. His book also has a complete bibliography of the papers referred to so you can download them and read them for yourself. Finally, the best fish (with omega 3) and chips are deep fried in lard and always have been. Once a week on a Friday, they can form part of a good balanced diet. --Aspro (talk) 15:57, 7 April 2010 (UTC)

And why would the those promoting low saturated fat oils have more money to spend than those promoting their high saturated fat products ? StuRat (talk) 18:19, 7 April 2010 (UTC)

I would that answer along these lines: First: don’t think of it as low verses high; that’s a sales and marketing position. People used to consume a variety of different fatty acids.

Second: Lard, beef dripping, mutton tallow, coconut oil were all established fat rendering industries. So was lubricating oils from rape seed. When plant breeders found that they could produce vegetable oils that were cheaper than traditional fats and that they could be modified to be used as pseudo substitutes, the breeders and oil processors were able to convince their governments to trumpet their products (and to give them attractive tax incentives to spend money on sales and marketing, applied research etc.). This, their government were/are willing to do, as it increases growth in exports. Also, by possessing these oils so that they had longer self life their profits increased further. These companies (like others in a competitive market place) used these profits to increase their market share. People new the price of lard but did not realize they where paying over the odds for vegetable oil. That’s how.--Aspro (talk) 18:21, 7 April 2010 (UTC)

Does "paying over the odds for vegetable oil" mean "getting subsidized discounts on vegetable oil" ? StuRat (talk) 18:56, 7 April 2010 (UTC)

?

I have forgotten the name of the logical fallacy that you're introducing but I get the drift of you question.

A landowner once waxed lyrical to me once about how much European Union subsidy he was getting per hectare of rape. So yes, I suppose he was able to sell it for less, than he would, if he did not receive the subsidy. However, a few years ago when I was doing some cost analysis for a friend who was about to open a restaurant, the traditional fats cost a lot more. Pig farmers in Europe/coconut farmers etc., work to very tight margins. They don’t get the same sort of preferential treatment as other fatty acid producers. So, I would ‘say’ (and I emphasis this because I don't have hard figures to hand ) that the public has paid the full cost of traditional fats AND at the same time, paid over the odds for vegetable oils for which the producer has also received government subsidies. So whilst Joe Public has been able to buy ‘cheaper’ units of food, the industry that produced it, and the retail trade that sold it, was able to extract more of a percent profit per unit.--Aspro (talk) 19:57, 7 April 2010 (UTC)

I think you're reading way too much into my Q. I just don't know what the expression "paying over the odds" means. StuRat (talk) 00:46, 8 April 2010 (UTC)

In that case: pay over the odds--Aspro (talk) 18:51, 8 April 2010 (UTC)

So it just means to overpay ? StuRat (talk) 00:09, 9 April 2010 (UTC)

I've looked into cooking oils for deep frying and there are many factors to consider. For example, how often do you deep fry? How do you keep the oil? Unless you're Bill Gates, cost is an important factor. For example you may think it worth spending say double for oil which lasts longer. But would it be better to use the cheaper oil but change twice as often? Nil Einne (talk) 23:12, 7 April 2010 (UTC)

Hey guys, enough already. I was asking about cleaning the fryer. Please step outside my question if you have other issues ;-)) Caesar's Daddy (talk) 18:57, 8 April 2010 (UTC)

Renal agenesis

Are there any simple symptoms to tell if you were born with one kidney (unilateral renal agenesis)? My father was born with one kidney, but he didn't find out until he was 31.--十八 09:29, 7 April 2010 (UTC)

This is something you'd need to see a medical practitioner for, as the easiest way to diagnose such a problem is by a scan. Regards, --—Cyclonenim | Chat  09:49, 7 April 2010 (UTC)

Have a look at this article. In particular, "URA [unilateral renal agenesis] is an asymptomatic condition usually discovered during routine prenatal ultrasono­graphy. Before the advent of prenatal ultra­sound, the diagnosis of URA was usually made incidentally when radiographic studies were performed for other reasons." The short answer is: no. Axl ¤ [Talk] 21:54, 7 April 2010 (UTC)

Advanced search engine for sound

Do you think there will be a possibility to search media by their envelope? Instrumental and vocal music can share similar envelop for example regardless their frequency spectrum and sampling rate, and so if a sample of music were submitted to the search engine such that I will search and compare other similar music.--Email4mobile (talk) 12:09, 7 April 2010 (UTC)

It certainly sounds possible. I don't think it exists yet (at least, I've never heard of it). Ways of searching for similar images are just starting to be invented (you can find them online, but they aren't very good yet). I expect finding similar sounds would be a similar problem. Come back in a few years. --Tango (talk) 12:48, 7 April 2010 (UTC)

A few years ago there was a service where you could call a phone number and (sorry the details are fuzzy) either hum a piece or hold the phone up to a radio and it would tell you what piece of music it was. No idea how limited a pool of choices ("stuff played on the radio" is a pretty small set!) or how well it worked. DMacks (talk) 12:57, 7 April 2010 (UTC)

I recall having seen (and more or less successfully tested!) an internet search engine where you could enter a rhythm pattern in plain text. The engine produced a list of popular songs matching the pattern. It was pretty nifty. This was about 10 years ago. DVdm (talk) 13:02, 7 April 2010 (UTC)

I remember one where you entered symbols to indicate whether the next note was higher or lower in pitch than the one before, and it worked out the tune from just that information. 86.21.204.137 (talk) 13:24, 7 April 2010 (UTC)

Yes! That's the one I had in mind. My memory got a bit rusty. Do you know whether it's still around? DVdm (talk) 13:38, 7 April 2010 (UTC)

Google is my friend:

• Songtapper for rhythmic patterns does good job.
• Click and sing or hum not tested - no mike.

DVdm (talk) 13:58, 7 April 2010 (UTC)

Oh hey, we have a Multimedia search page on the topic, and a list of articles about specific sites too. DMacks (talk) 13:06, 7 April 2010 (UTC)

The ear is something of a frequency analyzer, and responds to the frequencies present or the sound spectrogram rsther than to the shape of the envelope, which is more sensitive to phase than is the ear. Certainly it should be possible to search for a matching sound sample with a given envelope. But the envelope shape is not that critical to how we perceive a sound. Two performances of the same vocal or instrumental passage might sound the same to us, but look quite different on an oscilloscope. Edison (talk) 14:22, 7 April 2010 (UTC)

Well, I think Edison is right. I've just recorded a vocal song on one channel and its instrumental music on the other. I realized that envelops were almost different. I wonder how then our ear can recognize it? Is it just a frequency response or is their other kind of processing? --Email4mobile (talk) 15:20, 7 April 2010 (UTC)

Shazam can, when given an obscure cover of a well-known song, tell what the song is, but not who's covering it. CS Miller (talk) 19:33, 7 April 2010 (UTC)

germinating

In this image of a conker germinating, is the one on the right the root part or the leaf part? Thank you for your help 82.44.54.207 (talk) 13:12, 7 April 2010 (UTC)

Yes, it is a conker sprouting. The white visible part is the root, or radicle which you can see is trying to go downwards as it is positively geotropic. The leaf shoot will appear in a day or so and start to grow upwards. You need to get it into the ground or a pot if you intend to grow it. Caesar's Daddy (talk) 14:08, 7 April 2010 (UTC)

But how do you know it hasn't been turned over for the pic ? StuRat (talk) 14:15, 7 April 2010 (UTC)

Because I am 60+ years, I have seen more sprouting conkers than I care to count and this is a perfectly normal, regular-looking photo of a sprouting conker. If the conker had been placed with the sprout going upwards I would have concluded that it was either a badly posed conker or possibly a mutant conker with reverse tropism attraction - it happens. The main fault in my answer was not noticing it was a stock photo and then suggesting the OP plant it, doh! Caesar's Daddy (talk) 15:45, 7 April 2010 (UTC)

Then you didn't conclude it's the root because "you can see is trying to go downwards", but for other reasons. StuRat (talk) 17:24, 7 April 2010 (UTC)

Correct, but then I didn't claim that was the main ID feature, I just noted it as an aside. My main conclision was based on the fact that the first white pointy thing that comes out of the conker is the root!! Caesar's Daddy (talk) 21:59, 7 April 2010 (UTC)

Yes. The shoot that goes sky ward is not pointy but is a leaf bud that almost immediately divides into two (I seem to remember) as soon as the root hairs appear. --Aspro (talk) 16:48, 7 April 2010 (UTC)

Experiment at Geneva

Can any body explain in a simple language about the experiment going at Geneva ??? —Preceding unsigned comment added by 117.197.251.56 (talk) 15:03, 7 April 2010 (UTC)

I assume you talk about the Large Hadron Collider or LHC? Simply said, they accelerate charged Hadrons, i.e. protons or other atomic nuclei around a large vacuum tunnel to very high speeds, and then let them collide with each other. In the collision, a part of the kinetic energy of the particles is converted into new and sometimes interesting particles, according to E=mc² (E in this case is the kinetic energy of the particles, m the mass of the newly created particles - all somewhat simplified). Physicists have certain models about which particles should be created, and they check if these can be observed after a collision, confirming our current theories of matter. More interesting is the case that they cannot be observed, in which case they try to figure out what happened instead and how to explain it. --Stephan Schulz (talk) 15:16, 7 April 2010 (UTC)

(edit conflict with above) Are you referring to the Large Hadron Collider at CERN? Basically, they are taking subatomic particles (protons, in this case) and smashing them together at very high speeds. When particles collide with so much energy, lots of weird stuff happens (you create types of particles that normally aren't seen), and scientists try to examine the weird stuff that happens to figure out more about how the universe works. Experiments like this have been going on a long time (about 50 years), but the Large Hadron Collider is a lot bigger than anything else used before, and so can get particles moving at much higher speeds than any other particle accelerators. Because the LHC is bigger, and the collisions have more energy, scientists are hoping to see new types of weird stuff that they haven't ever observed (the most interesting thing would be the Higgs boson). Buddy431 (talk) 15:17, 7 April 2010 (UTC)

A Simple English article is at simple:Large Hadron Collider. The collider smashes protons together at very high speeds. The protons are destroyed and other things are made. Scientists measure what is made. AlmostReadytoFly (talk) 15:19, 7 April 2010 (UTC)

Unfortunately, that article is not simple English, but written at Kindergarten level and "simply wrong"... --Stephan Schulz (talk) 16:08, 7 April 2010 (UTC)

"Simple" does seem to mean "kindergarten-level" over there (technically, that's closer to a third to fifth grade reading level, but I get your meaning). It doesn't seem entirely wrong though. Technically, a proton *is* a hydrogen atom with its electrons "stolen". I'm sure physicists would slap their heads if someone tried to speak with them using the terminology in the article, but for children in early grade school or those with a weak grasp of English, it's close enough. What do you think is wrong with it? —ShadowRanger ^(talk|stalk) 18:40, 7 April 2010 (UTC)

See the edit history - I already fixed two whoopers. The black hole story is at least suspicious - how do we know that cosmic rays do not create black holes all the time? I thought the idea of Simple is to explain concepts using simple language, not to oversimplify the concepts. That seems to be very hard to separate, though. --Stephan Schulz (talk) 19:50, 7 April 2010 (UTC)

Yeah, that paragraph at the end was a joke. I'm actually okay with the original wording for your other edit though; "break" is pretty close to what they're trying to accomplish. The wording on black holes could use improvement, but given that we're talking about what are, from the point of view of the simple Wikipedia, two different things ("real" black holes vs. "transient" or "fake" black holes), it's understandable. Maybe something like: "The LHC is doing the same thing that cosmic rays do when they hit the Earth. Either no black holes are being created by the cosmic rays, or the black holes created are very tiny and would go away on their own. In either case, the LHC would be safe." ?—ShadowRanger ^(talk|stalk) 20:40, 7 April 2010 (UTC)

Side-note: It's really damn hard to write a description of particle physics without using any complex words. I'm amazed I managed to do it without going to three syllables. —ShadowRanger ^(talk|stalk) 20:40, 7 April 2010 (UTC)

Is this why there is (as yet) no Particle Physics for Dummies book available, I wonder? :) --Kurt Shaped Box (talk) 20:50, 7 April 2010 (UTC)

You joke, but there are Dummies books for absurdly complex subjects in Physics, including Quantum Physics for Dummies and String Theory for Dummies (which includes a section on particle physics). —ShadowRanger ^(talk|stalk) 20:56, 7 April 2010 (UTC)

Sweet. I was joking before - but yes, I might actually have to take a look at those... :) --Kurt Shaped Box (talk) 21:29, 7 April 2010 (UTC)

(Re. SRRIT): No, the "breaking" is a definitive no-no. If they "broke" the original particles, how could they ever make bigger (well, heavier) products from them? You need to get the energy into this somehow. --Stephan Schulz (talk) 21:23, 7 April 2010 (UTC)

Electric drill rating

I am confused by the fact that wired drills are rated in volts. Battery drills in watts. (Or the other way round.) What rating battery drill do I need to get solid power? I have had a 14w for some time, and it just does not have enough power, nor battery life. Help, please.Froggie34 (talk) 15:04, 7 April 2010 (UTC)

Watts describe the power the drill will consume/deliver (for electric motors, the difference is not very large). A wired drill should have a power rating of 500W or more - good ones often have more than one kW. Volts denote the voltage of the drill. In principle, voltage and power are independent (you can get more power by increasing either voltage or current, i.e. amps). In practice, wired drills will almost always have more power than battery drills, because it is not economically feasible to build very compact batteries that can deliver 500 W for any amount of time (and having them deliver this for a long time is not even technically feasible). But if you look carefully, both wired and battery-driven drills should have ratings of power (W). --Stephan Schulz (talk) 15:24, 7 April 2010 (UTC)

The way you said “solid power” makes me wonder if you mean Torque as well. I can read power tool spec. sheets but I still seek out a competent trades person, to see what he uses for the sort of use I am intending to do. You can’t really suss that out from a spec. sheet. Professionals will sometimes welcome a genuine request for their expertise in their choice in power tools. I have found it cheaper in the long run to accept what they say as being right. They use them day in day out and know all the cons and pros, and which offer the best value for money.--Aspro (talk) 16:33, 7 April 2010 (UTC)

Wired ones are rated in watts, and cordless ones in volts - and it's totally a gimmick. The volts makes no difference at all, they could make the same power drill with half the volts and double the current (amps). Do you need the drill for drilling or for driving screws? If for screws what you actually care about is torque. Or actually torque plus speed under load. There is no one good way for rating a drill. For wired, watts is a reasonable measure, but you will also want to check the toque - which is often hard to find. The unloaded speed is usually printed on it. And more or less, the higher the watts for the same speed means more torque. When you say "not enough power" what do you mean? Doesn't last long enough (watt hours)? Can't turn tight screws (torque)? Doesn't spin fast enough? Ariel. (talk) 18:25, 7 April 2010 (UTC)

I used to repair professional and consumer power tools at a tool shop for a few years and I would definitely recommend not to choose a tool based on what it claims its watts or volts are, those numbers are usually more misleading then useful. A cheap less efficient tool will usually actually have a higher wattage rating then a better and more efficient one. It's a very similar story with speakers, you can get nasty cheap 150w speakers for a few bucks but they will be total rubbish compared to some good quality 80w speakers. If you are looking for a good tool don't expect to pay peanuts for it, if you buy the cheapest one you'll get the crappiest one. I agree with the poster above to try to find a trades person and see what they use on the job, even if you spend a bit more to start with, you're much more likely to get a tool that will serve you for a long time. Also, you CAN get very good wireless tools these days but you will pay a lot more for it. Unless you actually have a specific need for a wireless tool, more then just pure "convenience", I still recommend wired tools. More reliable, last longer (batteries and even chargers typically go obsolete every few years), and much better price / performance ratio. Vespine (talk) 22:30, 7 April 2010 (UTC)

Thank you all very much. I need a drill to deliver effective power, so I suppose I mean torque. Anyway I am greatly helped.Froggie34 (talk) 08:31, 8 April 2010 (UTC)

gravitation

If gravitation is like accelerated frame of reference(as stated in general relativity) why don't the accelerated mass move away from the body creating the gravitational field? —Preceding unsigned comment added by 113.199.137.150 (talk) 17:04, 7 April 2010 (UTC)

Because the acceleration is in the oposite direction of what you are thinking, towards the body generating the field. Dauto (talk) 18:12, 7 April 2010 (UTC)

Organ donation

I'm trying to remember the term given to organ donations (such as kidneys) where you donate to a random person whom you don't know? I'm not considering it, just haven't a mind blank. Regards, --—Cyclonenim | Chat  17:44, 7 April 2010 (UTC)

I think it's typically called "nondirected donation" [20], but our organ donation article calls it "undirected donation". Paul (Stansifer) 17:50, 7 April 2010 (UTC)

Searching "nondirected donation" gave me the term I was looking for: altruistic donation :) thanks Regards, --—Cyclonenim | Chat  22:37, 7 April 2010 (UTC)

Time Travel

In a recent TV interview (available on youtube [here]), the physicist Brian Cox stated that "you can travel into the future at any speed you want relitive to other people". Can anyone help to explain what he means by this? This statement got me a bit confused! thanks! 80.43.182.69 (talk) 18:47, 7 April 2010 (UTC)

Well he's on Twitter at @ProfBrianCox. Why don't you tweet him and see what he says? --TammyMoet (talk) 18:57, 7 April 2010 (UTC)

Your "[here]" link seems to be missing. I suspect he's talking about time dilation, where time slows down for people going close to the speed of light, but continues at the same rate for everyone else. So, by adjusting your speed, you could also adjust how fast you go forward in time relative to others. However, you can't go back in time this way. See Time dilation and space flight. StuRat (talk) 19:04, 7 April 2010 (UTC)

I think it would have been less sensationalist to say that "in principle you can make time pass more quickly for yourself by building a spaceship that can fly close to the speed of light". However, there is no way to build such a thing with any technology we have. Also, this idea of "speeding up time" is not what most people think of when they think of time travel to the future - they imagine that you climb into this box the size of a telephone booth - type in some date in the future and press the Big Red Button and SHAZAAM!!! there you are in The World of Tomorrow! But that's not what Brian Cox is talking about. This would be more like: you climb into a gigantic rocketship - fire up the engines and S-L-O-W-L-Y (over a period of a year or two, get up somewhere close to light speed. Then, as you zoom along, you see events in the rest of the universe start to speed up. Everything inside your spaceship seems normal enough - but outside, there is some seriously weird stuff happening. When you are close to the time you want to be, you turn the spaceship around and start slowing down again (which takes another year or two) - and NOW you are "in the future". Not exactly "SHAZAAM!". But it's theoretically possible thanks to Einsteins' relativity. For the "SHAZAAM!" kind of time travel, you'd need to get into your spaceship and go into 'suspended animation' while the spaceship speeds up and slows down again...but we don't know how to do suspended animation either - so it's still not going to happen anytime soon. Of course all of this only works in the forwards direction. Once you're in the future, you are very definitely stuck there - and there is no similar way to travel into the past. SteveBaker (talk) 19:57, 7 April 2010 (UTC)

I'd say we're far closer to suspended animation than near light-speed travel. We can freeze and revive some simple animals, now we just need to figure how to stop ice crystal formation in our cells, and we could do the same. StuRat (talk) 00:39, 8 April 2010 (UTC)

Yep. There are prospects of taking genes from various fish and amphibians that can survive being frozen solid by having natural antifreeze in their cells. However, that kind of genetic engineering of humans has enough ethical concerns to push it quite a way out into the future. SteveBaker (talk) 02:20, 8 April 2010 (UTC)

For less drastic time dilation, you could always try living your whole life on top of the highest mountain you could find (ideally close to the equator). Granted, it wouldn't even add a second to your life (I don't care to do the math, but I've seen figures online that claim you'd "gain" a second every four millenia or so). Since the Earth bulges at the equator, and the mountain adds more height, your speed (relative to anyone else on the planet at a lower altitude) would be greater. Like I said, not practical, but an amusing concept. —ShadowRanger ^(talk|stalk) 20:28, 7 April 2010 (UTC)

Steve, that's not how it works. Moving away from Earth you would see Earth events redshifted, i.e., going slower. Moving towards Earth you would see them blueshifted, i.e., going faster. It does add up, overall, to more elapsed time on Earth, but not obviously. The right way to think about time dilation is in terms of the overall length of the paths through spacetime. If you have two curves, one of which is a straight line and the other of which wiggles around but starts and ends at the same place, the wiggly curve is longer (because a straight line is the shortest distance between two points). You can say that the wiggly line is longer "because of the wiggling" (i.e., the acceleration). But it doesn't really make sense to say that the wiggly line is "longer per unit length", whatever that would mean, in the places where it's at a large angle to the straight line—and that's basically what people are saying when they say that "time goes slower when you're moving quickly". -- BenRG (talk) 00:01, 8 April 2010 (UTC)

Yeah - I know - I was over-simplifying for the sake of making a comprehensible explanation. At least I didn't simplify to the degree Cox did! SteveBaker (talk) 02:18, 8 April 2010 (UTC)

Sorry, this is the link i meant to post [21], he makes the aforementioned statement about 2 minutes in, but fails to expand on it. Thanks! —Preceding unsigned comment added by 80.43.182.69 (talk) 22:24, 7 April 2010 (UTC)

Steve, just have to pull you up on your cryogenic stuff. ONE animal (an antarctic nematode) has been shown to survive INTRAcellular freezing. Fish don't freeze, they avoid freezing, which is pretty easy when you're in water - you just have to hope it doesn't freeze all the way to the bottom. I've only heard of freeze tolerant insects - no higher animals I can think off, and they avoid intracellular freezing, only coping with extracellular ice formation. Aaadddaaammm (talk) 13:15, 8 April 2010 (UTC)

Photographs

I take bad pictures. I know people that take very good pictures. Is there any technology in the foreseeable future that can render subjects more accurately? Imagine Reason (talk) 20:53, 7 April 2010 (UTC)

Well, autofocusing DSLRs already exist and can take very good pictures. True DSLRs cost a lot of money, but they're the best choice for advanced amateurs and many (if not most) professionals. Autofocus is a crutch (you can usually get better pictures if you learn to tweak your focus manually), but it's a good crutch for beginners. Combined with photo editing software like Adobe Lightroom, which can fix up flaws in lighting/exposure levels as well as tuning contrast and hue, a sufficiently determined amateur can produce effectively professional quality photos. Doesn't mean their pictures will be "art", but they can at least not look like cheap Polaroids. —ShadowRanger ^(talk|stalk) 21:06, 7 April 2010 (UTC)

Weird. I posted after Sperm Whale, but it didn't give me an edit conflict or anything, just shoved it in above your post. —ShadowRanger ^(talk|stalk) 21:07, 7 April 2010 (UTC)

What sort of camera do you have? A point-and-shoot or a bridge digital is less likely to take good quality photos than a DSLR. Also, what is wrong with the photos? If the composition is boring, then you have to learn to take better photos. If the images are noisy and poor quality, then it is the camera's fault. Hope this helps, --The High Fin Sperm Whale 21:04, 7 April 2010 (UTC)

A trend toward faster ISO settings (more sensitive sensors) will allow faster shutter speeds in low light than now, and greater depth of field in low light situations without needing a large lens opening. Automatically deployed electronic flash reduces subjects being in a shadow or under exposed in general. More powerful flash in future cameras might allow more use of bounce flash (bouncing it off the ceiling rather than direct flash) for a more natural appearance, and for subjects farther away. Some new cameras purport to be able to detect and focus on faces, and to take the picture when the person is smiling. Some cameras purport to automatically reduce motion blur. These features should spread to cheaper cameras and work better in the future. The display on the back of the camera lets you easily see how you have composed the photo (and make sure your thumb is not in front of the lens. Automatic rapid sequence of exposures reduces the need to precisely time the photo to catch the action. Larger memories in future cameras will allow more bracketing of exposure and more rapid fire sequencing, without filling memory. A camera klutz will not automatically get better pictures with a fancier DSLR than with an automatic point and shoot. I hope that future cameras are more rugged (not destroyed when dropped or splashed). If the future camera has what amounts to a self-stored tripod to keep it from moving around, (like a means of securely sticking it to a wall or table) picture sharpness would be improved due to less motion blur, and it would be easy to automatically take pictures of the same subject at high and low exposures, to combine correctly exposed parts of the scene in the shadow, and parts outside in sunlight, with exposures near enough the same time that subjects moving around is not a problem. It would also make it easier for the photographer to be in the picture, especially if a remote trigger and remote viewing screen were included. Motion-triggered photography would make surveillance or photos of animals visiting the back yard easier. Avoiding a loud-clacking mirror in the typical DSLR would make it easier to photograph things without calling attention. Edison (talk) 21:35, 7 April 2010 (UTC)

Hi Edson, what software is there around to combine images taken at different exposures to get a good result? Graeme Bartlett (talk) 22:01, 7 April 2010 (UTC)

Read High dynamic range imaging and HDR tonemapping & exposure for some suggestions. There are LOTS of software packages out there that relate to High Dynamic Range (HDR) imaging and photography. SteveBaker (talk) 02:13, 8 April 2010 (UTC)

I'm sorry I wasn't clear. I meant that I don't come out as nice-looking as I do in real life, while some other people look better than they are in person. Imagine Reason (talk) 03:26, 8 April 2010 (UTC)

OK, some hints then:

1) Learn which is your "best side" (it may be straight on, rather than either profile).

2) Before picture taking, sneak off to the bathroom to comb your hair, wipe off any sweat, tuck in the shirt, etc.

3) If you are overweight, hide the fat parts behind others, and wear dark colors and vertical stripes. Make sure pics are taken from above to hide double chins. If seated, put something on your lap you hide your belly, like a pet, kid, or pillow. StuRat (talk) 03:59, 8 April 2010 (UTC)

Just to note the 'vertical stripes' thing was on QI the other night stating that research has shown that vertical stripes don't make people appear more thin. 194.221.133.226 (talk) 08:32, 8 April 2010 (UTC)

... and be aware that most people perceive that they themselves look worse in photographs than others perceive them and worse than they perceive others. In this case, perception may not be reality. Is it because we seldom see ourselves in "real life"? Dbfirs 05:56, 8 April 2010 (UTC)

We usually see ourselves in mirrors, i.e. side-reversed. Humans are not quite symmetric, and the difference is significant. So on photos you don't look like you would expect to. --Stephan Schulz (talk) 08:40, 8 April 2010 (UTC)

This is true - and it's sometimes recommended that you judge photos and portraits of yourself by looking at them in a mirror. SteveBaker (talk) 19:19, 8 April 2010 (UTC)

Photogenic is the word that you are looking for, as in "I am not photogenic". At the end of that article is a link to How To Be Photogenic, which might answer your question. Mitch Ames (talk) 06:53, 8 April 2010 (UTC)

Also...good photographers don't necessarily accurately represent reality as it was (well maybe good forensic photographers) - but artistically they make use of tools and techniques to get the image to look how they want. Photographing people is no different. Taking photos of groups for instance regularly means that people have to bunch-up a lot closer than they would comfortable feel. By being much closer together the image looks better, more composed, perhaps even more 'natural' - yet the situation that created it is (for many) a bit worrying. The other factor that is huuuugely important is lighting - good lighting and bad lighting make for huge variance in whether something (or someone) looks good in an image or bad. Remember our eyes perceive the world somewhat differently to how a camera does (since it just captures anything from 1/50th of a second to 1/40,000 of a second typically). 194.221.133.226 (talk) 08:37, 8 April 2010 (UTC)

Camera-wise, the best thing you can do, is use a suitable focal length for the shot. This article by Ken Rockwell explains things clearly. [22]--Aspro (talk) 09:59, 8 April 2010 (UTC)

(I moved the following answer by Edison to the correct section - it didn't seem to say much about Time Travel!) SteveBaker (talk) 02:33, 9 April 2010 (UTC)

Since you clarified that your concern is how you look in photos rather than how to take photos, many celebrities on magazine covers have had their images extensively retouched, by Photoshop or otherwise. It is practically universal. Skintone is evened, nose hairs removed, wrinkles smoothed, broken veins in the nose removed, blemishes removed, banjo eyes fixed, suntan added, teeth whitened, extra chin removed, bald spot covered. This is one way technology can make your photo look better. Some people freeze when a camera is aimed at them and someone says "SMILE!" or squint, or fix their mouth in a phony rictus of a "smile which does not go all the way to the eyes." If a camera is aimed at you and takes a photo silently every little bit you might forget you were being photographed and then, at some point the instant might come where you have a pleasant and natural expression, and bingo, you have a better picture than usual. The key here would be good natural light and a memory which can capture a whole bunch of automatically taken photos. Edison (talk) 19:32, 8 April 2010 (UTC)

Titan arum

Just wondering, but the article on the Titan arum (Amorphophallus titanum) says it is a flowering plant. Does anyone have a picture of it flowering? Also, is this a picture of the titan right after it blooms? Thanks in advance, --The High Fin Sperm Whale 21:00, 7 April 2010 (UTC)

Yes, that's the inflorescence. It's not technically the flower, as the actual flowers are at the bottom of the central column (spadix), hidden by the spathe. -- 140.142.20.229 (talk) 21:08, 7 April 2010 (UTC)

Here [23] is a diagram that indicates, with labels, the component parts of the inflorescence. Richard Avery (talk) 21:52, 7 April 2010 (UTC)

Destruction of chlorate explosives

Can chlorate explosives be destroyed, e.g. by a bomb squad, by reacting them with hydrochloric acid?

KClO₃ + 6 HCl → KCl + 3 H₂O + 3 Cl₂ —Preceding unsigned comment added by Cheminterest (talk • contribs) 21:41, 7 April 2010 (UTC)

Such a reaction would surely release a lot of heat, which is bad around bombs. Additionally, Cl₂ is itself a pretty strong oxidizing agent, and would likely react with whatever the fuel in the bomb was. So yes, I suppose they could be "destroyed" that way, but the destruction might take place as a detonation, which sort of defeats the purpose. Buddy431 (talk) 00:18, 8 April 2010 (UTC)

Bomb squads sometimes detonate the bomb in place (after evacuating all civilians from the danger zone, of course) if there's no other way to get rid of it without endangering themselves and others. FWiW 24.23.197.43 (talk) 06:03, 8 April 2010 (UTC)

Yeah, but if you're trying to blow up a bomb, there's got to be better ways than pouring a nasty chemical on it, creating an even nastier chemical, and seeing what happens. I admit that I have no idea how bomb squads do dispose of bombs, but at first read, this doesn't seem to be a very good way of doing it. Buddy431 (talk) 14:21, 8 April 2010 (UTC)

They use a small satchel charge made of C4 explosive, just like in The Hurt Locker. 24.23.197.43 (talk) 00:16, 9 April 2010 (UTC)

April 8

population control

Communist China limited families to one child as national policy. Why now then does Communist China object to pornography which is proven to reduce the number of incidences of copulation both within a marriage and without thus automatically reducing the the number of children a male will produce? 71.100.3.207 (talk) 23:48, 7 April 2010 (UTC)

Perhaps the government should hand out blow-up dolls ? :-) StuRat (talk) 01:14, 8 April 2010 (UTC)

"proven"? Can you cite sources for any of these very doubtful claims of yours? Comet Tuttle (talk) 01:17, 8 April 2010 (UTC)

No, because if you are using porn then I do not want to interrupt that because it leaves more unattended ladies for me. 71.100.3.207 (talk) 04:14, 8 April 2010 (UTC)

It's because population control isn't the only thing that their government is concerned about. They would probably argue that any marginal benefits of porn in terms of limiting population growth was outweighed by the moral decline of society that it brings. I don't think I agree with either of those conclusions - but this is about their ideas, not mine! SteveBaker (talk) 02:01, 8 April 2010 (UTC)

Why does the Catholic Church insist on dictating other people's sex lives while turning away advice for their own? It's about power and fidelity to the organization. 67.243.7.245 (talk) 03:24, 8 April 2010 (UTC)

The Chinese government is very concerned with what it considers to be moral decay. It also gets a lot of political mileage from regulating pornography—it is (if I recall) something like the top reason they cite for needing to regulate their internet communications, and resonates very well as a justification within China. (Even outside of China, there are a lot of people who think regulating internet pornography would be a good idea, not realizing that the kinds of regulations you put in place for that are easily transferred to other realms of communication.) Communists of the Soviet/Chinese variety were always pretty uptight about sexual and social things despite their association with the "left" in the rest of the world. --Mr.98 (talk) 12:29, 8 April 2010 (UTC)

Miners "surviving" by eating sawdust and bark

At a page bearing "Copyright © 2010 The Associated Press" we find the article "Rescuers race to reach 32 trapped in China mine" which is one of a number of places i've seen/heard wordings like "The 115 miners survived for eight days underground by eating sawdust, tree bark, paper and even coal." A few have said ambiguous things like "staved off hunger", but i think it's widely known that unlike cattle, humans lack both the enzymes to digest cellulose, and the ability to harbor (as cattle do) the bacteria that do have the enzymes. I assume that putting some non-digestible bulk into your digestive tract may do your spirits some good, and possibly provide some respite from the sensation of "gnawing" hunger (incipient starvation), but is it possible that there's any benefit in terms of providing calories? My bet is that even if there's a tiny amount of sugar-bearing sap in sawdust, or of digestible substances in bark, the energy required to synthesize and excrete HCl and other digestive fluids is going to outweigh the energy extractable from the sawdust or bark. (This is not even weighing in the hazard of poisoning by bark, which in many cases includes substances that kill insects that try to eat it, or make at least make them go away, and are likely to be toxic to humans, as with most manufactured insecticides.)
So what's the chance that eating sawdust or bark (from the timber shoring up the ceilings, i assume) is a way to delay starvation? (For extra credit, is there anything in paper -- sizing? -- that makes it a better choice? And what about coal dust, which includes substances that can't even be burned?)
--Jerzy•t 00:55, 8 April 2010 (UTC)

Poor Haitians Resort to Eating Dirt. I couldn't understand this either. I'm afraid the article doesn't explain it, either. Bus stop (talk) 01:00, 8 April 2010 (UTC)

I agree with you that it wouldn't do any more than the placebo effect. One thing that starving people might have handy that could do some good is leather, if they could manage to boil out the tanning chemicals. StuRat (talk) 01:08, 8 April 2010 (UTC)

We have an article on Geophagy but I think we need an article on Edible clay. Bus stop (talk) 01:16, 8 April 2010 (UTC)

Experts claim habit of eating dirt may be beneficial for some. Bus stop (talk) 01:19, 8 April 2010 (UTC)

But humans can easily live for much longer than 8 days without food, so it's not like the minors needed calories. My guess is that they were just filling their bellies to reduce the sensation of hunger. Buddy431 (talk) 01:28, 8 April 2010 (UTC)

According to this survivalist website (http://www.survivaltopics.com/survival/edible-pine-bark/), many forms of tree bark (at least when freshly collected and cooked) are edible and nutritious. Dragons flight (talk) 01:41, 8 April 2010 (UTC)

No, eating wood does not do anything to delay starvation. To produce energy, the body needs organic chemicals like proteins and Sugars. Wood is almost 100% cellulose, which is basically a huge chain of the sugar Glucose. However, humans cannot digest cellulose. In fact, no animal can. Any animals that do (e.g. Termites) have to use bacteria in their stomachs to break it down into simpler sugars. --The High Fin Sperm Whale 01:52, 8 April 2010 (UTC)

If bacteria don't count, then animals can't digest very much of anything, on their own. StuRat (talk) 02:12, 8 April 2010 (UTC)

I gave my source. Here's two more discussing the potential to eat bark for nutrition [24][25]. Our own article on bark says: "The bark of some trees is edible...", and gives the example of a kind of bread made from tree bark. We eat lots of plants, like carrots and lettuce, that give us few calories per volume but aren't totally worthless. I suspect bark is in the same category. Not much useful nutrition but not zero either. If you believe there is nothing at all that is digestible in bark, then I suggest you give your source(s). Dragons flight (talk) 02:33, 8 April 2010 (UTC)

The issue isn't having no nutritional value, it's having fewer calories than it would take to digest. There may also be other "foods" which fall into this category. StuRat (talk) 02:39, 8 April 2010 (UTC)

But that's still assuming a conclusion without proof. I listed sources that say eating bark (at least under some conditions) can be beneficial. If you contend that it is a net negative, then what is your evidence / source? Dragons flight (talk) 04:28, 8 April 2010 (UTC)

At least one kind of bark can be beneficial; see Cinnamon. Nyttend (talk) 01:17, 9 April 2010 (UTC)

If you don't have to exert yourself, you can live for a very long time without food. There have been hunger-strikers who have lived for 70 days without food - so 8 days is very survivable. Now - if you don't have water, you're in trouble very quickly - but that evidently wasn't a problem in a flooded mine! So it's pretty clear that the bark did nothing than make their stomachs more comfortable - and since morale and the will to survive are very important in such situations, it could be said that eating it helped them - but not nutritionally. SteveBaker (talk) 02:09, 8 April 2010 (UTC)

This is how that works out for the minimal BMR of 1650 per day. A person with 32 lbs of body fat to spare to pay his BMR bill of 1650 calories per day has about 130,634 calories to spend. That's only about 80 days if his or her body only needed calories to burn. Most references, however, say two weeks at most. 71.100.3.207 (talk) 06:49, 8 April 2010 (UTC)

No - two weeks is far too little. Check out Hunger strike - and in particular, the various Irish republicans. Of the two major strikes, one involved nine people - and was called off when two of them died after 94 days(!), and in another case, around 8000 prisoners stopped eating - one died after 35 days and another after 37 days when the strike was called off. That's a pretty solid statistical sample. Out of 8,000 people - all but two survived for 37 days. We can imagine that those two deaths were of people who for one reason or another were more susceptable to problems - so the great majority would probably have survived much longer had the not returned to eating again. The fact that of 9 people, only two died after 94 days says that this is much more likely to be the ultimate limit. But in a more recent hunger strike, ten men died after between 46 and 73 days. Of course all of these people were lying still in bed for most of that time and had plenty of water (and in some cases, salt) - so their calorie requirements were minimal...but I think two weeks is a very low limit - there are no cases in Hunger strike of people dying after as little as 14 days...and even 80 days is by no means an upper limit. SteveBaker (talk) 19:15, 8 April 2010 (UTC)

I would expect there to be a fantastic difference in the length of time one can survive without food between individuals. Perhaps the 2 weeks would be for someone with anorexia, whereas Senor Lardo who is 450 lbs of bigmac fed blubber could likely surpass 3 months (assuming he does not have a stroke or something). So there should be a chart that determines how long you can go without food based on your weight and body fat%, rather then just using the median results of humanity as a whole. Googlemeister (talk) 20:35, 8 April 2010 (UTC)

Indeed - but the sample of 8,000 hunger strikers must represent a wide swath of people. Not a perfect statistical sample - but since every single one of those people survived for 34 days, it would have to be someone with some rather serious other condition to prevent them from surviving a month. Maybe the two weeks includes pregnant women or small children or something - but a moderately healthy, normal adult can go a month without eating - no problem. So (dragging this thread back on-topic) a bunch of good, strong miners would certainly have survived more than 8 days without resorting to eating bark. SteveBaker (talk) 02:26, 9 April 2010 (UTC)

Are there diets that cause a person to not defecate?

I have heard that there are diets that will cause a person not to generate any feces, but all my google searches (e.g. "how do i stop pooping") are turning up articles about how to stop a dog from pooping on the rug. Any help please? Is there such a diet? 207.237.228.236 (talk) 01:07, 8 April 2010 (UTC)

Just fasting. No food in, no food out, then you die. Or you could get all your nutrition intravenously, which would work for a while, but eventually you'd get an infection or a nutritional imbalance and die. StuRat (talk) 01:10, 8 April 2010 (UTC)

• The references you hear to feeding tubes (which deliver food to the stomach without need for swallowing) reflect the fact that caloric requirements alone inherantly limit how long life can be sustained by intravenous feeding. It may still be the case that the limit of what is feasible in the way of intestinal surgery is set by whether the patient will starve on IVs before their traumatized intestinal tract can resume its job of absorb nutrients (first priority: calories).
  It works like this: too many calories per cc, and your blood is too thick to flow thru the capillaries, or maybe first the osmotic pressure destroys blood cells and the hemoglobin plugs up the nephrons in your kidneys. But the IV can't flow any faster than your kidneys can extract water from your bloodstream unless it's pumped in, driving up your blood pressure and destroying your kidneys (for most people, IIRC, before a stroke or random hemorrhage kills you). So they give you all the salinated sugar-water that flows in, and your body burns fat (leading, IIRC, to ketoacidosis which is pretty bad for reasons i can't remember) to make up the difference, and when you run out of surplus fat, it starts burning muscle and, at some point, indispensable fat. (Can you survive to the point where it starts cannibalizing the fatty myelin that many nerves need to function properly? Dunno.) At any rate, its not that hard to get dead by living on an IV.
  --Jerzy•t 05:33, 8 April 2010 (UTC)
  

• You'd think there'd be solutions to those probs, like blood thinners and multiple IV sites. And, if the kidneys aren't fast enough to keep up, how about dialysis ? StuRat (talk) 13:36, 8 April 2010 (UTC)

Presumably if you eat "foods" that totally dissolve in water you'd have a shot at not having any solid waste. I'd imagine one could prolong life with nothing but Gatorade and sugar water, but I don't think it makes for a healthy permanent lifestyle. Dragons flight (talk) 01:48, 8 April 2010 (UTC)

You are thinking of a low residue diet. 68.116.194.175 (talk) 01:55, 8 April 2010 (UTC)

Low residue, yes - but zero residue, no. SteveBaker (talk) 02:10, 8 April 2010 (UTC)

• Hmm, not zero bcz your gut bugs keep multiplying as long as you get adequate nutrition via your stomach?
  --Jerzy•t 05:33, 8 April 2010 (UTC)
  

US Army C rations were specifically designed to provide a fairly balanced diet while minimizing the amount of fecal matter produced. Not zero-residue of course, but pretty low-residue by most people's standards. FWiW 24.23.197.43 (talk) 06:06, 8 April 2010 (UTC)

Are you thinking of “Total" Parenteral Nutrition where someone has had their gut removed?[26]--Aspro (talk) 11:19, 8 April 2010 (UTC)

I don't see how you could eat Army rations (or anything else) if you had your gut removed. 24.23.197.43 (talk) 00:20, 9 April 2010 (UTC)

I assume that Aspro tabbed once too much, making it look like they were replying to you, when they were really replying to the original Q. StuRat (talk) 00:58, 9 April 2010 (UTC)

Help with a physics question

This is a link to a past pre-tertiary (grade 12) Physics exam: [27]
Read Question 9.
The answers to the exam are found here: [28]
Why do the positive and negative charges repel, as it would appear on the diagram on the answers document? I thought opposite charges attract.
--Alphador (talk) 06:12, 8 April 2010 (UTC)

The positive and negative ions are not repelling one another. They are moving in different directions because of the magnetic field. See Faraday's law of induction for a comprehensive explanation. There is a section devoted to magnetic flow meters. Dolphin51 (talk) 06:24, 8 April 2010 (UTC)

Is the ability of scopolamine to suspend free will an urban legend?

I read an article about it on the Internet but it (the article) seemed to have a tongue-in-cheek feel to it. 20.137.18.50 (talk) 12:28, 8 April 2010 (UTC)

This is covered, at some length, in the scopolamine article. -- Finlay McWalter • Talk 12:37, 8 April 2010 (UTC)

Seems like it would be a much better interrogation tool than waterboarding if it really works. 20.137.18.50 (talk) 15:15, 8 April 2010 (UTC)

Agreed with you on this one. From what I know (and don't quote me on this), scopolamine was used as early as World War 2 by both the Nazis and the Allies (and possibly even earlier). It's still occasionally used today, but these days the truth serum of choice is usually sodium pentothal. Now, the biggest limitation of both these drugs (and of truth serums in general) is that, because they work by partially suppressing the conscious mind, they only give reliable results when you're interrogating someone for specific information that they're hiding -- for example, if you know that your captive is planning a terrorist attack, and you want to know when and where it will take place. If, on the other hand, you want information that requires your captive to do some conscious thinking, you're better off using other means, like blackmail or something of the sort. 24.23.197.43 (talk) 00:32, 9 April 2010 (UTC)

Life project

Is there a distributed program (like the SETI program) that starts with the fundamental constituents of life responsible for the synthesis of inorganic and organic compounds or proteins, fats and carbohydrates to see what things might be created in cyberspace that could be useful or stable in the real world? 71.100.3.207 (talk) 14:21, 8 April 2010 (UTC)

Folding@home and Rosetta@home are the first things that occur to me. They may not exactly hit your target, but they're close. --Tagishsimon (talk) 14:58, 8 April 2010 (UTC)

Wikipedia's "team" at Folding@Home is currently ranked around 2,500 out of 175,000 teams: [29] 75.41.110.200 (talk) 15:17, 8 April 2010 (UTC)

Wow that's very poor, my team is ranked 971 and we have lesss membres than wikipedia. Keep it running.--92.251.159.172 (talk) 16:57, 8 April 2010 (UTC)

No! It's good! It means that Wikipedians are busily using their computers for editing this humungous dictionary instead of vegging out on the sofa while their computer runs the Folding@home screen saver! SteveBaker (talk) 18:36, 8 April 2010 (UTC)

I run it in the backround all constantly, it doesn't affect my performance much when playing graphics intensive games either.--00:42, 9 April 2010 (UTC) —Preceding unsigned comment added by 92.251.166.223 (talk)

Is there a way to join the Wikipedia team? I wouldn't mind getting in on the action. 130.126.130.146 (talk) 19:28, 8 April 2010 (UTC)

Just enter the team number for Wikipedia in the client setup. Team number is 42223. —ShadowRanger ^(talk|stalk) 20:10, 8 April 2010 (UTC)

Are there any distributed programs that are used to create translations for written texts in an extinct language? Similar to brute forcing an encryption? Googlemeister (talk) 20:29, 8 April 2010 (UTC)

I'm fairly sure that would be impossible for all practical purposes. Words won't match up one to one, grammar will differ, etc. A different alphabet (which is basically what you're doing with encryption, though it's a really complex alphabet for anything more powerful than substitution ciphers) is the least of your worries. And if the language is based on pictograms, you're basically completely screwed without huge amounts of material to work from. There is a reason we needed the Rosetta Stone to decipher Egyptian hieroglyphics, and a reason that the U.S. used Navajo code talkers during WW2. Even in less difficult cases, it would still amount to writing an AI program, not a code breaking algorithm. —ShadowRanger ^(talk|stalk) 20:50, 8 April 2010 (UTC)

SUV fuel tank

What is a typical volume for a current model year SUV gas tank? Ballpark number is all I need. ike9898 (talk) 14:49, 8 April 2010 (UTC)

20-30 gallons ? Less than that for compact SUVs, and more than that for full sized. StuRat (talk) 14:59, 8 April 2010 (UTC)

20-25 gallons, depending on the size of the SUV. Ford's lineup, for instance, ranges from 16 gal (the Escape) to 33 gal (the Expedition) with the 22 gal Explorer in the middle. Honda's Element has 17 gal, the Pilot 19 gal. — Lomn 14:59, 8 April 2010 (UTC)

On the high end, the 3/4 ton 2010 Chevy Suburban has a 39 gallon tank. StuRat (talk) 15:50, 8 April 2010 (UTC)

Be aware that the gallon comes in different versions - your tankage may differ, depending on location. 87.81.230.195 (talk) 16:36, 8 April 2010 (UTC)

I would expect that all these values are in US liquid gallon (≈ 3.8 L), since the others are for dry measure and for use in the UK and Canada (where I suspect liters are used, by now). StuRat (talk) 16:47, 8 April 2010 (UTC)

Thank you all. ike9898 (talk) 16:58, 8 April 2010 (UTC)

What is the technical name for the sensation that there is someone behind you?

...and does Wikipedia have an article about this phenomenon? In a related question, is there a specific term for the aversion (not perhaps on the level of a phobia, but similar) one might have for having people behind you? Thanks, Lithoderm 15:14, 8 April 2010 (UTC)

Paranoia would include the feeling that you are being watched. StuRat (talk) 16:07, 8 April 2010 (UTC)

It depends on whether you mean an hallucination, such as that that can be induced by the God helmet or spatial acoustic awareness caused by sensing changes to the echo in a room, which can happen when someone walks up behind you but many people don't normally notice. The latter is I suppose, a form of echo location. Some people feel unsettled when they first experience an anechoic chamber due to the sudden absence of this phenomena. If it feels 'eerie' then you might be reacting to sub-audial Infrasound.-.--Aspro (talk) 16:59, 8 April 2010 (UTC)

Honey-bee prefered row crops in the U. S.

I am trying to think of what row crops honey-bees may like best. Do they tend to shy away from plants that have tassels like corn or millet? Anyone have any Ideas? —Preceding unsigned comment added by 160.36.38.126 (talk) 15:40, 8 April 2010 (UTC)

Most grains with tassels (such as corn and wheat), and even most grasses, are wind-pollinated. They don't rely on insects like bees to do any of the pollination, and as such do not usually provide nectar as an enticement to attract bees. (Bees will visit corn tassels to collect pollen, though.) Bees prefer to feed on plants with visible flowers - indeed most scientists believe (showy) flowers evolved specifically to attract insect pollinators. -- 140.142.20.229 (talk) 16:46, 8 April 2010 (UTC)

Bees pollinated crops list: [30] Many of them are planted rows including vegetables and oilseeds, even apples and almonds (they're planted in rows, too!) Others aren't like alfalfa and clover. Occasionally oilseeds are broadcast planted. Rmhermen (talk) 18:22, 8 April 2010 (UTC)

They also seem to like roses. FWiW 24.23.197.43 (talk) 00:39, 9 April 2010 (UTC)

Gastroenteritis

Not a question for medical advice. Exactly how does the virus/bacteria cause stomach cramping and bloating in gastroenteritis? I did read this but I was looking for an explanation why or how this causes the stomach muscles spasms and bloating. --Reticuli88 (talk) 15:44, 8 April 2010 (UTC)

Abdominal bloating is generally caused by the accumulation of gasses in the gut. Generally, these gases are the result of waste products produced by Gut flora; that is all of the bacteria that normally live in your digestive tract eat what is passing through your gut, and they expel gas as a waste product. In a healthy person, most of the gas production occurs at the end of the colon and in small amounts, so it is easily expelled by farting. If you have gastroenteritis, you have some sort of bacterial infection higher up in the disgestive tract, and THOSE bacteria are producing lots of gas in a place where it is not easily expelled, because it has to pass through a lot more of your digestive tract. The normal involuntary muscle movements that pass food along through your upper intestines (see Peristalsis) is inadequate to move this gas to your bum faster than it is produced, so the gas builds up and becomes uncomfortable. Additionally, the pressure on the walls of your intestine generated by this gas, besides being uncomfortable in itself, can cause the muscles lining the digestive tract to cramp or spasm (think of a charley horse in your intestines), which itself can be very uncomfortable. --Jayron32 18:54, 8 April 2010 (UTC)

Thanks Jayron. Is your explanation what describes a bacterial gastroenteritis? What happens when the gastroenteritis is from a viral infection? --Reticuli88 (talk) 19:09, 8 April 2010 (UTC)

I believe in the viral case, the intestinal lining inflames, causing similar effects. Opportunistic infections (or even overgrowth of "good" bacteria) would lead to other symptoms (such as excess gas production). —ShadowRanger ^(talk|stalk) 20:45, 8 April 2010 (UTC)

Armour vs railguns?

Approximately what thickness of steel would be needed to stop a shell about the same size as that fired by a 5 inch naval gun travelling at 6,000 m/s? What about a projectile comparable to a 16 inch naval gun shell travelling at the same speed? What materials (tungsten? DU?) would be more effective than steel at stopping these projectiles, and approximately what thickness of those would be required?--92.251.159.172 (talk) 16:53, 8 April 2010 (UTC)

There are many more variables than just speed. Is this a solid shell, high explosive, shaped charge, DU? Can the shell be guided? Can we use ablative or reactive armor? Rmhermen (talk) 18:25, 8 April 2010 (UTC)

What is the range that the shell is fired from, that will make a difference. You have a ton of drag at mach 17, maybe even enough to trash the projectile before it arrives at the target. Googlemeister (talk) 18:59, 8 April 2010 (UTC)

I got the impression that the speed was the instantaneous speed at point of impact, not the launch speed. If he meant launch speed, then range becomes one of the most important aspects, for exactly the reasons you gave, and a definitive answer is going to become more of an equation. —ShadowRanger ^(talk|stalk) 19:03, 8 April 2010 (UTC)

Hi 92.251.159.172. If your a loyal and humble citizen of the wonderfully, quaint and picturesque Duchy of Grand Fenwick, then chill out... you're a landlocked principality and battleships will not be able to navigate that far up river. --Aspro (talk) 19:26, 8 April 2010 (UTC)

Replying to Rmhermen: the armor-piercing properties of HE and shaped charge shells depend on the size and shape of the explosive charge and do not vary with the projectile speed (which also means that there's no particular advantage in firing them from a railgun as opposed to, say, a conventional anti-tank cannon -- what, no article?). The most effective round for a railgun would prob'ly be a depleted uranium shell (high density, excellent hardness, and good high-temperature properties). 24.23.197.43 (talk) 00:50, 9 April 2010 (UTC)

Another complicating factor is the angle of the impact. If the round arrives at a perfect right angle to the armor, it can penetrate through far more armor than if it impacts at an angle. If you look at the design of tanks, they go to a lot of trouble to make sloping surfaces everywhere they can. Since the angle of impact also depends on the range (because of the parabolic trajectory), this adds another complication to the range-versus-penetration curve. SteveBaker (talk) 02:05, 9 April 2010 (UTC)

Need help identifying a Prunus species

Can anyone identify this species of Prunus? I'd like to upload some more photos of the same tree, but I'd rather have a correct ID first. I'm thinking it's probably Prunus americana? –Juliancolton | ^Talk 16:57, 8 April 2010 (UTC)

Looks like Prunus americana to me. Does it have thorns? How do the flowers smell? P. americana flowers smell rather nasty. You may want to try asking at the Dave's Garden plant identification forum [31], they are very good there. Winston365 (talk) 01:58, 9 April 2010 (UTC)

Posted at that forum (thanks!) and I'll look more closely at the tree tomorrow. Thanks for the help. –Juliancolton | ^Talk 03:37, 9 April 2010 (UTC)

shewees

are sheewees issued as military kit to female soldiers/sailors/airwomen? —Preceding unsigned comment added by 86.128.31.228 (talk) 18:07, 8 April 2010 (UTC)

No. SteveBaker (talk) 18:29, 8 April 2010 (UTC)

Given the difficulty in finding a place to store it safely and the arguable benefit of being able to pee standing up instead of squatting, I can't imagine why they would. Hell, with practice women can pee standing up (even if some find it mildly gross); if the squatting is really an issue it would be simpler to learn to pee standing. —ShadowRanger ^(talk|stalk) 18:55, 8 April 2010 (UTC)

The space shuttle has a similar device:NASA: Waste Collection System. Everything that NATO uses has a NATO Number. I don't currently have access to the data base but I can imagine extended duration missions where such a device would prove to be a great convenience. --Aspro (talk) 19:42, 8 April 2010 (UTC)

The space shuttle needs it because of the whole "no gravity" thing (male astronauts use it too). Astronauts dislike floating around in their own pee; can't imagine why. ;-) Soldiers of either gender are perfectly capable of peeing in the field without special equipment. —ShadowRanger ^(talk|stalk) 20:08, 8 April 2010 (UTC)

Quote:"female soldiers/sailors/airwomen"? (my emphasis) Wikipedians, (whose knowledge about female aviators doesn't stretch beyond what they know about their own great aunts antics during their time as test pilots for the local broom factory), may not appreciate the practical problems women face. Oh come on! Haven't you ever been on a an adventure holiday with the opposite sex and far, far away from a 'Holiday Inn' with showers and all those other things..? Err... well..? Evaluation of urine collection equipment in female aviators. AND DON'T FORGET TO LOWER THE SEAT, AFTER YOU HAVE READ THIS!--Aspro (talk) 20:51, 8 April 2010 (UTC)

Again, that's for a case where there is a problem for both genders. Men can't pee effectively while flying a fighter jet either. If you read the link, they are simply redesigning an existing urine collection device for male pilots to accommodate female pilots as well. It uses a funnel, but it is by no means indicating standard issue sheewees. —ShadowRanger ^(talk|stalk) 20:57, 8 April 2010 (UTC)

True story: I used to work for a company that made flight simulators - the fancy kind with big hydraulic motion bases. We built a military simulator for either a big transport aircraft or a large helicopter (I forget which) that had a "crewman relief tube" mounted in the side of the cockpit for the pilots to pee into during long missions. In the real aircraft it had a lever that opened an external valve to suck the pee outside the plane. The interior of the simulator had to be very realistic - and we'd buy up a lot of real aircraft parts to kit them out properly - and we had an actual crewman relief tube to put into the simulator - but the guys who were building the cockpit didn't know what the thing was for so nobody bothered to make it go anywhere. To make it fit into the cramped space of the simulator cabin, they cut off the outside end with the valve and blocked it up with a metal plate. Needless to say, the simulation was evidently good enough that at one pilot got "lost in the moment" and forgot he wasn't in the real aircraft, and with a certain inevitability the tube rapidly filled up - and squirted pee back all over his trousers - and all over the floor of the simulator! Subsequent versions of the simulator replaced the authentic tube with a section of appropriately painted broom handle! SteveBaker (talk) 01:51, 9 April 2010 (UTC)

is the following experiment valid?

Is it valid to test whether prayer helps plants with the following experiment: 1. control of doing nothing versus test of NutraGro plus prayer that the plant will grow at only a normal level despite the NutraGro. In all other respects (except for the addition of the NutraGro and the lack of prayer and of prayer respectively) the groups will be exactly the same, and blinded until the end.

If there is no statistically significant difference between the groups despite of the prayer, then the conclusion is that prayer must have worked. If there is a statistically signifant difference, then the prayer must have failed, as the prayer was obviously not granted.

Thanks for any tips you might have on this methodology. Note: please don't suggest the obvious idea of praying that a positive do happen, rather than fail to happen, as the God to whom these prayers are addressed is not of that personality, but very badly tempered and disposed to nothing except causing ruin and failure when so pressed. Thank you. 82.113.106.90 (talk) 19:40, 8 April 2010 (UTC)

The experiment as stated sounds flawed. Consider instead: 1)Control group: no prayer, no fertilizer. 2)Prayer, no fertilizer. 3) Fertilizer, no prayer. 4)Fertilizer and prayer. Each Group should be several individual pots, rather than one big tray with a bunch of plants, to spread random effects of over/underwatering and avoid a seeming significant effect of the experimental variable which is just due to watering, how near the window, etc. This way each plant is actually independent of the other plants, and you have the degrees of freedom you think you do in the statistical analysis. Then do Analysis of variance with one of the statistical packages. I would expect a main effect of fertilizer and no significant effect of prayer. If the fertilizer alone had no benefit, then the experiment as stated would false conclude that the negative prayer worked. Now consider the statistical power of the experiment: failure to find a significant effect of prayer might just mean you had too few plants (fallacy of accepting the null hypothesis. Edison (talk) 19:53, 8 April 2010 (UTC)

(edit conflict) I am completely confused by what experiment you wish to do? Are you praying for the unfertilized plant to grow? Or are you fertilizing all of your plants and then praying that they all grow exactly the same rate? Praying for nothing to happen, and then having nothing happen, is hardly an experimental proof of prayer. It would work far better if you only had one variable, so what I would do is to plant a series of plants under the exact same conditions (level of watering, fertilizer, sunlight, etc) and then you pray that some of the plants grow, while you don't pay any attention to the others... However, you should be aware that even the Christian bible says "Don't put God to the test", i.e. God knows your motivation for praying, and He is inclined to respond in the negative to any prayer that is intended solely for the purpose of testing Him, so if you are taking a Christian understanding of prayer, a negative result would not disprove the power of prayer. Furthermore, there's the axiom "God answers all prayers. Its just that sometimes His answer is "no"..." So yes, you could structure a proper scientific experiment to test the power of prayer, however there are aspects of prayer which, as explained in the scriptures, would render fairly useless the results of any such experiment. Prayer is a matter of faith, and such matters are usually outside of the realm of falsifiability, thus are outside of the realm of science to test. --Jayron32 19:57, 8 April 2010 (UTC)

As I explained, the prayer is not directed to the God of the bible. Rather, to a God who just meddles and causes things to fail, which He (supposedly) reliably does at the least prodding. This God doesn't care if you test Him. He just wants something to wreck, and is happy to be asked to do so. In this case, I will be asking Him to have the NutraGro fizzle and fail to work. 82.113.106.90 (talk) 20:20, 8 April 2010 (UTC)

SO you invented your own God, gave him some personality traits arbitrarily, and you are testing to see if praying to your God, who you created and whose characteristics you decided he should have, using rules you made up will confirm or deny if he responds to prayers in the manner in which you have decided he should? What is the point in that? --Jayron32 20:29, 8 April 2010 (UTC)

It's no worse than testing against any other god. Aside from a more extensive history and a larger group of followers, it's all basically the same thing. If he said he was praying to Loki or Coyote or any other trickster deity and expected similar results, would that somehow be better? —ShadowRanger ^(talk|stalk) 20:41, 8 April 2010 (UTC)

Well, it is, because all religious belief systems involve some form of Divine revelation whereby the Supreme Being or Beings makes themselves known to the Faithful. There is a difference between a valid religious belief system, and making stuff up in your free time. Ultimately, however, the premise of the experiment is flawed not because of the god that the experimentor chooses to pray too (be it Yahweh, or Loki, or the Invisible Pink Unicorn), its that matters of faith are not falsifiable. If some idea is not falsifiable (that is, it could never be proven false) then it isn't an experimentable idea. --Jayron32 21:00, 8 April 2010 (UTC)

Who's to say his particular deity doesn't make itself known by making you consider its existence in a moment of boredom? Perhaps that is the source of the revelation. Not to mention that revelation isn't a prerequisite for religion, particularly in animist religions where you don't need to have a tree inform you that it houses a supernatural spirit. Beyond that, if his deity is in fact as predictable as he believes, then it would be falsifiable. Just because most religions make vague and unverifiable claims doesn't mean his religion has to as well. It just means that it's not very likely his religion will survive very long. —ShadowRanger ^(talk|stalk) 21:16, 8 April 2010 (UTC)

For the record, I have personally invoked a very similar deity to the OP's, specifically the "Demons of Irony" and/or "The Universe's Non-stop Hate Parade". I was just joking around. Maybe I missed a divine revelation? ;-) —ShadowRanger ^(talk|stalk) 21:19, 8 April 2010 (UTC)

There are two variables different between your control group and your test group (the prayer and the NutraGro), so it's a bad experiment. If you want to test the effect of prayer, then you need to either give NutraGro to both groups or neither, otherwise you are also testing the effect of NutraGro and you won't be able to separate the two effects. --Tango (talk) 20:15, 8 April 2010 (UTC)

The problem with your proposal is that I don't know what "fails to work" means, since you don't have a control that doesn't get the NutraGro. How about the control is the NutraGro and no prayer for it to fail, the test is the NutraGro with a prayer for it to fail, and a calibration group is without NutraGro and without prayer. That way, if there is a difference between the first two groups, the third group can help judge whether the NutraGro really failed (as opposed to just was somehow statistically signifantly different) with the prayer for it to fail as compared with without. 82.113.106.90 (talk) 20:20, 8 April 2010 (UTC)

I endorse Edison's response above. (The original poster asked a similar question here on February 24, in case anyone feels like reviewing the answers given back then.) Comet Tuttle (talk) 20:53, 8 April 2010 (UTC)

One would think that such a meddlesome deity would be liable to bless the NutraGro plant with outrageous growth, in an attempt to foil your experiment. AlexHOUSE (talk) 22:22, 8 April 2010 (UTC)

Apples numbing the lips.

Hey Ref Desk. Every time I eat an apple whole, my lips become somewhat numb. They feel stiff and feelingless against each other, something like rubbing your fingers together when you have paresthesia in your hand. Sometimes I catch myself drooling a little bit, and the effect usually fades away gradually over the next fifteen or twenty minutes. What's the deal? AlexHOUSE (talk) 22:14, 8 April 2010 (UTC)

This is NOT medical advice (I am not a doctor and cannot diagnose you!), but it sounds superficially to me like you are allergic to the apples or something on them. I suggest talking to a doctor or allergist about this—they can tell you for sure, and whether it means you should avoid or be careful with apples or not. Apple allergies are apparently not uncommon, I gather from Googling. --Mr.98 (talk) 22:31, 8 April 2010 (UTC)

See also Cross allergy. 75.41.110.200 (talk) 23:04, 8 April 2010 (UTC)

A quick search of "cross allergy" led me to Oral allergy syndrome, which seems pretty close. Thanks! AlexHOUSE (talk) 23:10, 8 April 2010 (UTC)

People with allergy towards birch pollen often experience those exact symptoms, which are caused by cross allergy, as stated above. Other vegetables that might provoke similar symptoms are raw carrots, pears, cherries, peaches, hazel nuts. Heat treatment of the vegetables tends to remove the problem, e.g. boiled carrots cause no symptoms, raw carrots do. If you have are worried about this, and in particular if you experience other symptoms than those you have described, you should seek medical advice, and not the advice of random strangers on the internet. --NorwegianBlue ^talk 00:21, 9 April 2010 (UTC)

Why do we need vitamin D?

Everyone knows that vitamin D is used by the body to take up calcium and transport it to the bones. Vitamin D also plays a role in the immune system. However, if you look more closely at the precise role of vitamin D here, what you see is that vitamin D only acts as a switch to turn on the production of certain proteins that do the real job.

We also know that vitamin D can only be made by organisms using UV light. The vitamin D we can get from food (e.g. fish) is also ultimately derived from UV light. The question is why all organisms have made the functioning of certain important processes dependent on a unessential substance that can only be made in a cumbersome way. Count Iblis (talk) 23:21, 8 April 2010 (UTC)

You have to consider that when this developed, all humans lived in the tropics, where access to UV light just wasn't an issue. Access to anything that comes from food, on the other hand, would have been a problem whenever a period of famine occurred. So, with vitamin D, unlike other substances, there was a backup plan for when the food containing it (like fish) became unavailable. StuRat (talk) 00:52, 9 April 2010 (UTC)

It goes back even further than that. Unicellular organisms have been taking advantage of photoconversion to make Vitamin-D analogs for millions of years. An ancient example of this process is that ergosterol in the cell membranes of some primitive organisms absorbs UV light more readily than nucleic acids, thus providing protection against a mutagen. Over evolutionary time, these compounds (and other useful molecules like them) were adapted for additional purposes. Quite elegant, really. What makes you see it as "cumbersome"? --- Medical geneticist (talk) 01:36, 9 April 2010 (UTC)

Vitamin D is a hormone. Like most hormones, it simply serves as a signal to activate some processes and repress others. And like most hormones, it acts upon many different systems in the body. And like most ancient and conserved hormones, the relative importances of various functions varies among organisms. What else would you like to know? alteripse (talk) 04:45, 9 April 2010 (UTC)

Sexual attraction to skeletons

Is there a recognized scientific name for people who are sexually attracted to/aroused by skeletons? —Preceding unsigned comment added by 140.198.32.131 (talk) 23:58, 8 April 2010 (UTC)

In Still life painting there is something called the "nature morte," which contains a skull. I find this line in that article:

"Also starting in Roman times is the tradition of the use of the skull in paintings as a symbol of mortality and earthly remains, often with the accompanying phrase Omnia mors aequat (Death makes all equal)." Bus stop (talk) 00:03, 9 April 2010 (UTC)

Necrophilia is close, but is defined as attraction to corpses and dead things, not necessarily skeletons. Intelligentsium 00:08, 9 April 2010 (UTC)

A male skeleton can have a "boner" or Baculum. Cuddlyable3 (talk) 00:24, 9 April 2010 (UTC)

Not if it's human. StuRat (talk) 00:50, 9 April 2010 (UTC)

Isn't sexual attraction to skeletons the logical end of the "you can never be too thin" quote ? StuRat (talk) 00:50, 9 April 2010 (UTC)

Since necro is from greek, and the greek word for skeleton is skeleton, I guess it would be skeletophillia. Ariel. (talk) 07:27, 9 April 2010 (UTC)

Use of imaging in cancer diagnosis

How can imaging alone determine the source of cancer in the body? I've just learned that an elderly distant relative has been diagnosed with cancer in two different parts of the body; based on imaging alone, the oncologist believes that it originated in one part of the body, even though it's apparently no more pronounced there than in the other part. Please don't take this as a request for medical advice; I simply can't understand how images can reveal that one spot of cancer is the source and a similar spot of cancer is the result of metastatis. Nyttend (talk) 01:09, 9 April 2010 (UTC)

Not necessarily images, but certain tests of immunohistochemistry can identify metastases. 76.235.109.131 (talk) 01:15, 9 April 2010 (UTC)

(after EC) The oncologist is probably using additional sources of information (clinical judgment and knowledge of typical patterns of cancer incidence and metastasis) in conjunction with the imaging to come to a "most likely" explanation. Additional confirmatory tests, such as a biopsy (and the aforementioned pathology studies), are generally involved in making a definitive diagnosis. --- Medical geneticist (talk) 01:18, 9 April 2010 (UTC)

Causality

How does information travelling faster than the speed of light disrupt causality? I've read this mentioned many times, but I haven't seen any justification for it. Thanks. 173.179.59.66 (talk) 02:41, 9 April 2010 (UTC)

Basically, if you can send a signal faster than the speed of light, and if the means of doing so works the same in all reference frames, then you can also send information back in time. So then someone from 2100 could send you a signal telling you to kill his grandfather, and you get the grandfather paradox. See tachyonic antitelephone for how this would work. --Trovatore (talk) 02:44, 9 April 2010 (UTC)

(ec) I'm no Gandhi but I bet it is because there is no single "now" but only frames of "now" and if you could send information faster than light then you could disrupt all into someone's frame. 82.113.121.111 (talk) 02:47, 9 April 2010 (UTC)

reading the above (first to post in edit conflict) it seems I was right :) maybe I am a gandhi... 82.113.121.111 (talk) 02:47, 9 April 2010 (UTC)

I live on Alpha Centauri and have your cat under my care. Your cat dies, and I send a faster-than-light message to you (on Earth) telling you that it died. That message--the effect of the cat dying--would arrive before you would see the cat die if you had an enormous telescope. That can't happen; the effect cannot precede the cause in any reference frame. --99.237.234.104 (talk) 03:02, 9 April 2010 (UTC)

Trovatore's answer is correct but may not be clear enought. The point is that for any faster than light movement there is always some reference frames in which that movement is seen as motion backwards in time which violates causality. That happens because of the relativity of simultaneity. In other words, if you can move faster than light then you also can move backwards in time. Dauto (talk) 03:24, 9 April 2010 (UTC)

It's a little subtler than that. Just going backwards in time in someone's coordinate system isn't enough in itself. Suppose I can send a signal that, in your coordinate system, leaves from Earth in January, 2012, and arrives at Alpha Centauri, around 4 light-years away, in January, 2011.

That doesn't get you the grandfather paradox, because if you send the signal back to Earth the normal way, it won't arrive until sometime in 2015. So you can't send a signal back to cause it not to be sent.

To close the loop, you have to repeat the trick, and send the signal back to Earth, if not backwards in time, then at least at four times the speed of light or better.

That's why I specified frame-invariance. It's logically possible that there might be a distinguished frame of reference in which you could send a signal faster than light, but because the method is not frame-invariant, you still would not be able to get causal loops. That would, of course, contradict relativity, but only in regimes where it's never been tested. --Trovatore (talk) 05:30, 9 April 2010 (UTC)

@99.237.234.104: Wouldn't you be able to account for the speed of the message and, correcting for it, see that cause didn't precede effect?

@Dauto: Would you be able to show me how you get that mathematically? Otherwise I'd just be taking your word for it. 173.179.59.66 (talk) 04:37, 9 April 2010 (UTC)

crash landing fatality rates - higher for helicopters or fixed-wing aircraft?

Seeing the news that a NATO helicopter in Afghanistan went down overnight with 4 presumed deaths got me wondering about crash-landing survival rates - if I'm military personnel, so I have a better chance of surviving a helicopter being shot out from under me / suffering severe mechanical failure or a fixed-wing aircraft? Numbers please, not speculation. I can do that myself! 218.25.32.210 (talk) 06:38, 9 April 2010 (UTC)

You would not believe what we have. To compile these statistics, however, one would need to go over those numbers to set up one's own graph. What we are looking for is the survival rate of crashed aircraft, rotary versus fixed. You do not explicitly state if you would like to discriminate based on "crash landing"; some aircraft that are shot at do explode in the air. I have been able to locate a source for your desired information: This forum's second poster has a lot of sources posted, and may be able to help you. Please note these are statistics for one year, and, in addition, concern the civillian market. What should be clear, however, is that the accident rate (not casualty rate) with helicopters is so vastly higher than airliners, that it would take great statistical deviance to suggest there is not also an accompanying casualty rate. This is speculation, of course, but it is educated. I could not produce numbers for helicopter accident fatalities/casualties versus fixed wing numbers, but I think these should be easy to gather from some of the sources mentioned in that link. 88.90.16.251 (talk) 08:21, 9 April 2010 (UTC)