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September 3

brown sugar

What is the chemical name of the drug commonly known as "brown sugar" —Preceding unsigned comment added by Dbeein (talk • contribs) 01:05, 3 September 2008 (UTC)

Brown sugar (disambiguation) says: A "street name" for heroin. See also a Google search on "brown sugar" heroin. PrimeHunter (talk) 01:24, 3 September 2008 (UTC)

Clarity of Glycerin soap

Since glycerin soap is simply homemade soap (without glycerin removed), why is it clear and not opaque? Do this have something to do with the alignment or molecular arrangement of the soap molecule with glycerin? Sjschen (talk) 01:13, 3 September 2008 (UTC)

just gossip here, but I thought the clear soaps were first cleaned using ethanol to make them look nice. Polypipe Wrangler (talk) 00:36, 4 September 2008 (UTC)

As I understood it was so that if you dropped it in water, it wouldn't end up being a hazard for you tripping on it because you could clearly see it. 66.216.163.92 (talk) 01:48, 5 September 2008 (UTC)

Separating a test tube mixture

I was given this problem a few days ago, and I was wondering if someone had any ideas on how to do this easily. This is the original question:

"You are given a test tube that contains the following mixture of substances

• sand
• salt
• sawdust
• iron filings
• benzoic acid

Salt and benzoic acid dissolve in water, while the sand, iron, and sawdust (which is

less dense than water) do not. However, benzoic acid does not dissolve until the

temperature of the water is above 50 degrees Celsius. Use this information to devise

a method to separate the mixture so you could return to me 5 vials each containing

one of the five pure substances in the mixture."

My first idea was to use a magnet to separate the iron filings from the mixture. Then you could add room temperature water to the mixture, and strain the contents so that you would be left with salt water that could be boiled and thus separating the salt from the water. But then I can't figure out a way to separate the sand, sawdust, and iron filings from the mixture. Any help would be greatly appreciated! Thanks in advance! - jesusfreak210 (talk) 03:32, 3 September 2008 (UTC)

You're right up until the final statement; you've already separated out iron filings. To separate sand and sawdust, take advantage of their differences in density. anonymous6494 04:05, 3 September 2008 (UTC)

Ok thanks, thats what I was thinking. And the iron filings thing was just a typo... sorry. Thanks again! - jesusfreak210 (talk) 04:14, 3 September 2008 (UTC)

There was an old puzzle of separating salt and pepper; you combed your hair with a plastic comb and the pepper is attracted by static electricity. I wonder if sawdust might be attracted in the same way.--TrogWoolley (talk) 22:10, 3 September 2008 (UTC)

So you add hot water. Then:

• Sawdust floats - none of the others do - so you can skim them off.
• Iron filings are magnetic - so you can stick a magnet into the test tube and pull them out.
• Sand sinks to the bottom - and isn't magnetic - so you can pour off the rest of the liquid and recover the sand.
• Benzoic acid and salt both dissolve.
  • Benzoic acid is only soluable in hot water - so cool the mixture and the benzoic acid comes out of solution and can be filtered out with filterpaper.
  • The Salt can then be recovered by boiling the water until there is none left.

Of course, in reality, you'll have somewhat salty sawdust, iron filings and sand - but you can repeat the process as many times as necessary to progressively dilute the salt to whatever degree of purity you need. SteveBaker (talk) 22:21, 3 September 2008 (UTC)

Steve, I understand your answer was well intentioned, but please try to avoid the urge to outright do students' homework for them. --68.166.144.211 (talk) 15:39, 4 September 2008 (UTC)

Just a piece of practical advice: wrap the magnet in paper or something for if the iron filings stick directly to an iron magnet it's very difficult to remove it. – b_jonas 22:32, 6 September 2008 (UTC)

Blindness disease

Blindness (novel) and the related Blindness (film) present a plot premised on an epidemic of blindness triggered by some unspecified infectious agent.

I realize that in the real world there are no diseases that causes blindness to spread like the flu. However, I am wondering if there are any communicable diseases at all where blindness is a major symptom. Some form of bacterial agent that affects the eyes perhaps? Thanks indulging my idle curiousity. Dragons flight (talk) 05:02, 3 September 2008 (UTC)

Syphilis and onchocerciasis come immediately to mind. In susceptible hosts (e.g. AIDS but also in others), there are many, including cytomegalovirus, varicella zoster virus, herpes simplex virus, and Pneumocystis jirovecii. It's actually a pretty long list. Scray (talk) 05:06, 3 September 2008 (UTC)

Probably should clarify that only tertiary syphillis and neurosyphillis present with visual problems. You would not experience this symptom with primary syphillis, by far the most common in industrialised nations, since we almost always catch syphillis in it's primary stages before it progresses to secondary, tertiary or neurosyphillis. Tertiary syphillis and neurosyphillis are more common in immunocompromised persons, such as those suffering from AIDS. —Cyclonenim (talk · contribs · email) 10:34, 3 September 2008 (UTC)

Fair enough, but I'm in a U.S. city and I've seen 2 people with sight-impairing ocular syphilis just in the past 6 months. One of them did have HIV (not AIDS), but the other did not and the point is that it's still happening. Scray (talk) 11:21, 3 September 2008 (UTC)

What about viral conjunctivitis? It spreads fast and when people who haven't been exposed to it to get it they often cannot open their eyes with swelling. In West Africa where I used to live it was called "Apollo's sickness" because there was a huge rapid epidemic of it after the return of the moon shuttle. Not permanent but very fast like flu and up to a week of practically no sight.--BozMo talk 15:21, 3 September 2008 (UTC)

At the bottom of the onchocerciasis article, there's a template which can be expanded to reveal all kinds of eye diseases. Notably Trachoma, a bacterial infection which spreads between people and has claimed the sight of 8 million people worldwide. EverGreg (talk) 18:56, 3 September 2008 (UTC)

Solvents of common pharmaceuticals

Removed by original questioner who was fed up with the obstructionist antics, assumptions of bad faith, trolling and general lack of good will of certain editors who really should know better. DuncanHill (talk) 22:58, 3 September 2008 (UTC)

(edit conflict) Yeah, we are now officially less helpful than Yahoo! Answers. (HTH, the technique given involves solvents the OOP said he tried, but maybe the technique is at issue.) -- Coneslayer (talk) 22:58, 3 September 2008 (UTC)

Long-term monogamy in mammals

Which mammals (one example I know is Peromyscus polionotus) show long-term monogamy? Otolemur crassicaudatus (talk) 11:27, 3 September 2008 (UTC)

Swans, parrots, red wolves and humans are a few well known ones. I can't find a full list, but true monogamy is very rare, at least according to this. JessicaThunderbolt 12:00, 3 September 2008 (UTC)

Swans and parrots are mammals now? DuncanHill (talk) 12:19, 3 September 2008 (UTC)

I need my head examined! Thanks for correcting me. JessicaThunderbolt 12:28, 3 September 2008 (UTC)

Physics

Hi, why is physics different than other natural science (studies)? Thank you. —Preceding unsigned comment added by Atacamadesert12 (talk • contribs) 15:33, 3 September 2008 (UTC)

Read physics and natural science and you'll find many answers to your question. -- kainaw™ 16:27, 3 September 2008 (UTC)

I'm not sure exactly what your question is about, but physics, as a natural science, has the distinction of dealing with the most fundamental of abstractions. Other scientific disciplines deal with more complex systems at various higher levels of abstraction. --72.94.50.58 (talk) 00:45, 4 September 2008 (UTC)

What "other natural science"? Physics is THE natural science. The rest are either just special cases (like chemistry) that has grown too large that they have to be broken out but they too are physics, or just stuff people are trying to sell as natural science (but is really applied science, humanties, or, worse, pseudoscience). – b_jonas 22:27, 6 September 2008 (UTC)

Wikipedia:Unidentified flowers

Please identify the flowers at Wikipedia:Unidentified flowers and delete the page once completed. Thanks. Suntag (talk) 16:53, 3 September 2008 (UTC)

No, thanks. — OtherDave (talk) 17:39, 3 September 2008 (UTC)

Maybe you've mistaken us for the Bounty board? JessicaThunderbolt 17:45, 3 September 2008 (UTC)

How much do you want? 93.132.165.7 (talk) 18:31, 4 September 2008 (UTC)

Don't mind the other replies—I personally think this is a perfectly legitimate request for the Ref Desk. We wouldn't be jabbing at Suntag if he had posted the pics on this page and asked us to ID them, would we? If anyone knows of good resources for the identification of flowers (or other plants, for that matter) post 'em here; I'd find it useful information.

For reference, there are half a dozen images of flowers, snapped in Belize. Good hunting! TenOfAllTrades(talk) 19:41, 3 September 2008 (UTC)

I don't. Would you give such a command to a real-life reference desk librarian? --Sean 14:50, 4 September 2008 (UTC)

"A command"? Which command is that? Axl (talk) 19:01, 4 September 2008 (UTC)

Would you ask a "real-life reference desk librarian" about Higgs bosons, evolution or other such things? —Cyclonenim (talk · contribs · email) 20:43, 4 September 2008 (UTC)

That's not a command: that's a question. Axl (talk) 21:13, 4 September 2008 (UTC)

Okay. Would you askdemand that a librarian should define the word entropy? The point stands, we are not librarians. We are a group of people interested in different subjects. —Cyclonenim (talk · contribs · email) 23:26, 4 September 2008 (UTC)

What is the problem? An editor asked politely for people to identify some flowers. He said please and thank you. He didn't clutter up this page with a large gallery, but thoughtfully made a separate page for them. DuncanHill (talk) 23:31, 4 September 2008 (UTC)

"Would you askdemand that a librarian should define the word entropy?"

— Cyclonenim

Would I? I would neither ask nor demand that (as you well know). I already have an idea what entropy is (but would need to look up a formal definition). I know how to find out answers to these "definition" questions without asking for help. However not everyone has these skills, notably newbies (to Wikipedia) and younger people. It is ironic that this area is called "Reference desk". The introduction states "The Wikipedia reference desk works like a library reference desk." The librarians' work at reference desks is mainly to find books and articles, to induct new members, and answer questions about borrowing items from the library. Wikipedia's reference desk isn't a desk. It is viewed by dozens of users who answer questions, often highly specialist (e.g. Higgs bosons). Axl (talk) 07:39, 5 September 2008 (UTC)

I SEVERELY ORDER YOU ALL TO REMOVE INSTANTLY AND WITHOUT THINKING ANY QUESTIONS THAT COULD BY, IN EVEN THE MOST HYPOTHETICAL ASPECT, BE CONSIDERED AS SEEKING FOR MEDICAL, LEGAL OR PROFESSIONAL ADVICE. I FURTHER COMMAND THAT YOU CHECK ANY ANSWERS OF YOURS AS WELL AS OF ANY OTHER PEOPLE AGAINST ALL LAWS OF EVERY EXISTING GOVERNMENT. Hope that helps. And, yea, remove that, too. 93.132.165.7 (talk) 18:31, 4 September 2008 (UTC)

Monogamy and Evolution

From what I understand (which is admittedly very little) about the evolution of our species, monogamy/pair bonding seems to be viewed as a helpful mechanism for protecting the weaker infant and mother and ensuring the replication of our genes. If this is true, I would think that the seperation of parents would be highly unusual, but this is not the case, especially in Western cultures. So why are parents so ready and able to deviate from the course seemingly plotted by our genes? Thanks in advance! 90.192.223.228 (talk) 19:29, 3 September 2008 (UTC)

The basic answer is that monogamy is evolutionarily advantageous to a parent only if it increases their inclusive fitness, which generally equates to the expected number of offspring successfully raised. (The "generally" is there because this simple definition does not take into account the fact that healthier/richer/etc. offspring may themselves have a higher chance of successfully passing on their genes.) Also, monogamy is typically only practical if it is in the interests of both parents — for most species, there's little one parent can do if the other parent decides to just up and leave. Typically, the parent more inclined to leave is the male, since their initial investment in the offspring in lower and the potential gain from seeking more mates higher; thus, monogamy is usually only stable if the improvement in the survival odds of offspring with both parents around to raise them is significant enough to compensate for the reduction in further reproductive opportunities the male must give up to take care of his earlier offspring. This is not quite true, since, if there is some way (e.g. elaborate and costly courtship rituals) for the female to try to predict the "fidelity" of males, they may prefer those males that are more likely to stay around and thereby stabilize monogamy even in the presence of incentives for males to cheat, but it's still a pretty good first approximation.

Even then, the choice between staying monogamous or looking for other mates is in reality not always an either-or decision, and there are strong evolutionary incentives for both parents to try to get "something for nothing" if they can get away with it. For males, this may mean trying to mate with other females even while only looking after one's "primary" family: though the gain may be uncertain, this costs little for the male. For females, it may involve trying to mate with a seemingly fitter, but already paired, male (and thereby hopefully gain better genes for one's offspring) while trying to convince another male to raise said offspring as his own. The end result of all this is a complicated game of cheating and counter-cheating strategies, for which strict monogamy and polygamy are simply two extremes along a wide and complex spectrum.

Incidentally, if anyone thinks I've been basing the above paragraphs on observations of human behavior, that isn't really the case: all this evolutionary complexity is much more clearly observable for example among various nominally monogamous bird species. Indeed, the fact that such simplistic reasoning, based on studies of species with a simple social structure, coincides so well with observed behavior even among such a complex social species as humans is quite surprising. Indeed, it's true that human behavior is in many ways yet more diverse, in large part thanks to our capacity for cultural evolution and for forming complex societies with ties extending beyond the pair level. Nonetheless, that fact that, even among species with simpler, more deterministic social behavior, evolution generally does not favor strict monogamy should at least suggest the unlikelihood of such inescapable genetic imperatives in a species as complex as ours. —Ilmari Karonen (talk) 21:04, 3 September 2008 (UTC)

Insect Identification

I recently found this insect and haven't the slightest idea what it is. It's about two inches long, holds its wings like a damselfly when at rest, and was found in Colorado. Photos one and two of it. Thanks in advance. PetrusCuniculus (talk) 20:07, 3 September 2008 (UTC)

It looks like some species of Dragonfly...but I'm no expert. SteveBaker (talk) 03:39, 4 September 2008 (UTC)

Looks like an antlion. Matt Deres (talk) 17:41, 4 September 2008 (UTC)

It's definitely an antlion. Thank you! —Preceding unsigned comment added by PetrusCuniculus (talk • contribs) 19:17, 4 September 2008 (UTC)

Wifi - any dangers?

Hello wikipedia,

I have no idea if i'm opening up a can of worms here but, here goes. Is there a health risk associated with having your wireless router in your bedroom? I can't find a discussion of the health risks on wikipedia but surely people like the Daily Mail must have ran stories?

Thanks, 82.22.4.63 (talk) 19:47, 3 September 2008 (UTC)

From the discussions I was able to find from a google search, not likely. Maybe if you tape the router to your head and walk around with it 24/7, but besides that? No. Paragon¹²³²¹ 19:54, 3 September 2008 (UTC)

(ec) Depending on the exact position of the router in your bedroom, your significant other may complain about it and demand that you put it somewhere else. Whether this constitutes a health risk is debatable (and may depend on the circumstances), but I do seem to recall some studies suggesting that people with healthy sex lives tend to live longer on average.

Also, if you're thinking of installing the router in your bedroom in order to use a laptop in bed, it's likely that disturbances to your circadian rhythm due to excessive late-night computer use, not to mention the possible ergonomic problems from bad posture etc., may indeed have both acute and chronic health effects.

Finally, please remember that the Reference Desk may not offer any actual medical advice. The standard Wikipedia medical disclaimer also applies. —Ilmari Karonen (talk) 20:01, 3 September 2008 (UTC)

See Wireless electronic devices and health. JessicaThunderbolt 20:05, 3 September 2008 (UTC)

Your significant other may hit you for spending too much time on Wikipedia in the bedroom. Clarityfiend (talk) 02:04, 4 September 2008 (UTC)

It seems very unlikely that WiFi would be a problem. Compare to a cellphone: A cellphone has to push it's signal a mile or more - often through walls - and you hold the antenna less than an inch from your body. WiFi only goes a few hundred feet, it doesn't work well through walls - and you rarely get within a few feet of it. Because the amount of radio energy you might absorb decreases as the square of the range - merely being 100 times further from your WiFi antenna than you are from your cellphone antenna means that the power you'll absorb is 10,000 times less. Since MANY studies of cellphones have failed to produce a conclusive link between cellphone use and general health - we can assume that the risk from WiFi is vastly less than the amount needed to produce any kind of health issue. SteveBaker (talk) 03:24, 4 September 2008 (UTC)

WiFi Laptops. Presumably it would be a sensible precaution for people of childbearing age and younger NOT to sit or recline for long periods with a laptop on their lap with the WiFi switched on and its antenna close to reproductive organs. I now use mine at a table etc, or with the WiFi switched off. Perhaps a precautionary health warning would be in order, pending further research. GilesW (talk) 16:55, 10 September 2008 (UTC)

Looking for references about cats

Hello, I just read a couple of facts about cats and I would like to check if they are really true. I would be very pleased if you could confirm or refute these facts, and provide weblinks where I can read more about it.

These facts are:

• a) old age in cats is not gradual like in humans; it appears suddenly, and lasts approx. 1 year before the animal dies.
• b) domestic cats are not very wary when crossing roads. they seldom look around when they are about to cross, and therefore get run over relatively often.

Thanks to anyone who can help. Leptictidium (mt) 20:39, 3 September 2008 (UTC)

I can testify from experience that my cat is very cautious when crossing roads — they are, after all, open areas often populated by big noisy things. If there's any sign of traffic — whether vehicular or pedestrian — on the road, he'll prefer to wait in a suitable hiding place until the way is clear, and when he does decides it's safe to cross, he'll do it quickly. However, I doubt he has a particularly good understanding of how cars actually behave, and thus sometimes his decisions on when it would be best to stay and when to cross may seems, if not unwise, then at least quite surprising from a human viewpoint.

Indeed, I suspect a particular risk is that, for cats, avoiding danger normally means avoiding being seen. Thus, a cat crossing a road will stay hidden in the bushes until he thinks the way is clear, and then dash across. Should the cat misjudge, this gives a human driver very little chance to react and avoid a collision. —Ilmari Karonen (talk) 21:13, 3 September 2008 (UTC)

It varies with the cat, in the second instance. Some cats are very good about roads. Some are not. I've no idea what accounts for the difference. --98.217.8.46 (talk) 21:44, 3 September 2008 (UTC)

BTW I've read Elizabeth Marshall Thomas say that her dog used to listen for cars instead of looking for them; it had no problem crossing the street whenever it was safe. --Kjoonlee 05:23, 5 September 2008 (UTC)

Statistically, the lifespan of a cat kept indoors is 12 to 14 years, while that of a cat allowed outdoors is about four years. [1], [2]. A goodly amount of that difference is due to automobiles. You can read more by Googling for "cat lifespan indoors outdoors". - Nunh-huh 05:33, 5 September 2008 (UTC)

Cystic fibrosis

The article on Cystic fibrosis says: "The CFTR gene is found at the q31.2 locus of chromosome 7, is 230,000 base pairs long, and creates a protein that is 1,480 amino acids long. The most common mutation, ΔF508 is a deletion (Δ) of three nucleotides that results in a loss of the amino acid phenylalanine (F) at the 508th (508) position on the protein. This mutation accounts for two-thirds of CF cases worldwide and 90 percent of cases in the United States; however, there are over 1,400 other mutations that can produce CF.[32]"

My question: do these 1,400 mutations also occur on alleles in the CFTR gene, or do these mutations occur on other genes? If the latter is true, is each mutation also a three-nucleotide deletion? Thanks, Nishkid64 _{(Make articles, not wikidrama)} 21:33, 3 September 2008 (UTC)

All known CF-causing mutations, if I'm not mistaken, are mutations of CFTR. The mutations vary widely in their change and effect, many are insertions of a stop codon, but there's plenty of missense mutations and frame-shift mutations, too. [3] — Scientizzle 22:26, 3 September 2008 (UTC)

This database shows the variety, also including promoter and splicing mutations. — Scientizzle 22:29, 3 September 2008 (UTC)

Another source for references to papers on CF inheritance is the Online Mendelian Inheritance in Man page on cystic fibrosis or on CFTR proper. - Nunh-huh 06:35, 5 September 2008 (UTC)

Invisibility Cloak

This article says that a major flaw in invisibility cloaks is that if you were inside one, the world would be invisible to you. Since objects behind an invisibility cloak are perceived as transparent (hence, invisible), what would it look like if the entire world and universe were transparent? This does not make sense to me. I'm sure you would see something, even if it is just your own reflection. Any ideas?--ChokinBako (talk) 23:05, 3 September 2008 (UTC)

If I understand the article you've linked correctly, from inside you will see the cloak as a black barrier. Algebraist 23:16, 3 September 2008 (UTC)

More accurately, you wouldn't see anything, since it would be dark inside the cloak. This is true by definition, since an invisibility cloak cannot let any light in from the outside without being at least partially visible. I'm not sure offhand what would happen if you had your own light source (e.g. a lamp) inside the cloak: presumably either the light would leak out (thus betraying your location, but still not helping you to see), or, more likely, it would be reflected back from the cloak (possibly in funny ways, since we're talking about some seriously weird optics here). —Ilmari Karonen (talk) 23:31, 3 September 2008 (UTC)

Actually, you could of course make the cloak look like any ordinary (opaque) material from the inside, by the simple expediency of lining the inside of the cloak with said material. —Ilmari Karonen (talk) 23:34, 3 September 2008 (UTC)

You could have a couple of tiny pin pricks for eye holes. Since they could be really close to your eyes, you could see quite well and they would be very difficult for anyone outside to notice. --Tango (talk) 23:39, 3 September 2008 (UTC)

An interesting question would be what happens to light that would've passed through the eyeholes. Obviously, light that hits the eyeholes directly simply goes through the hole and gets absorbed by your eyes, so the holes should appear (mostly) black from the front. But what about the light that would've come out of the cloak through the eyeholes? In general (handwaving away all those pesky details about actual construction of physical invisibility cloaks) I see two possibilities here: it gets either absorbed or retroreflected. The former simply makes the eyeholes appear black from the other side as well. The latter, however, might be more interesting if you were, say, thinking of writing a science fiction story with such devices in it, since it would imply, among other things, that if you were wearing an invisibility cloak in the dark and someone shone a light at the back of your head, your eyeholes would act as retroreflectors. Oopsie... —Ilmari Karonen (talk) 00:56, 4 September 2008 (UTC)

Presumably it would be absorbed, I can't see any reason for it to be reflected, nothing has happened to the other side of the cloak. --Tango (talk) 02:42, 4 September 2008 (UTC)

What silliness. Obviously any reasonable invisibility cloak will magically duplicate each photon that reaches it. That way one photon can be passed to the inside to allow the wearer to see and another can be sent out the back so as to make the wearer appear invisible. Dragons flight (talk) 00:37, 4 September 2008 (UTC)

Yes - and it is very hard to duplicate photons without magic. There is no way that they could have light sensing material in the cloak that could feed video to an interior screen. Cameras and monitors? Truly magic. -- kainaw™ 00:51, 4 September 2008 (UTC)

Without magic it is very hard to remain invisible if your cloak is made of "light sensing material". APL (talk) 01:13, 4 September 2008 (UTC)

Current invisibility cloak research uses fiberoptics to bend light around an object and send the light on its way on the opposite side of the object. If only one out of every million or so photons was detected, it would not destroy the "invisibility" of the cloak. -- kainaw™ 01:16, 4 September 2008 (UTC)

I think we're all missing something. In "real" invisibility research, you aren't expected to be invisible when viewed from every possible direction. The main requirement is for camoflage - and in that case, you probably know roughly where the enemy is coming from - so light coming from behind you has to be absorbed and regenerated at your front - or routed around you or something - but light coming from in front of you could pass through the "cloak" and allow you to see normally.

It would be really tough to make a "cloak" that would make you invisible from every direction because whatever devices are routing light from behind to your front would be blocking some of the light coming from the front toward your rear. When you also consider that light coming from (say) 20 degrees to the right - also has to be detected by sensors that overlay the emitters for front/back transmission - and you rapidly realise that true 360 degree invisibility is very hard to imagine indeed. SteveBaker (talk) 03:33, 4 September 2008 (UTC)

Actually, real invisibility research (no quotes required) does involve being invisible from all directions, as I understand it. See [4]. --Tango (talk) 06:07, 4 September 2008 (UTC)

In a futuristic sci-fi cop story some years ago, cops on a stake-out routinely sat in a car in which each window was a video display of what a camera diametrically opposite saw, so that the cops sitting in the car were practically invisible. But the same camera pointing East could display on the inside of the East window an image for the cops inside to watch. This would clearly yield some parallax artifacts if someone was walking by the car, but might be less obvious than being able to see 2 guys sitting in a car eating donuts and drinking coffee all day. An "invisibility cloak" does not have to be perfect to be better than just standing there in broad daylight. Edison (talk) 04:39, 4 September 2008 (UTC)

The bigger problem is that that only works if you look at the window from directly in front of it. If you look from the side, you'll see something completely wrong. Far better just to have tinted windows. --Tango (talk) 04:52, 4 September 2008 (UTC)

Not so new apparently [5] —Preceding unsigned comment added by TrapdoorTrevor (talk • contribs) 13:47, 4 September 2008 (UTC)

September 4

Zoom H2 Handy Recorder

Sometime ago I saw a link (may have been on a blog) to a page on the audio chips used in the Zoom H2 Handy Recorder. I cant find it now, can anyone help.

Its the Texas Instruments TLV320AIC32 low power stereo audio chip according to someone who took a zoom H2 apart.

You can look at this page : [6] or, better, but in german : [7]

Going through walls

Someone told me this once: "Say you had your on a wall. Eventually your atoms will line-up perfectly that your hand will actually go through the wall. But the changes of that happening is so small, it would take millions of years. But even after that it probably wouldn't happen."

Is this true? Is there anything on Wikipedia on this? I think it was from a book or something -- Coasttocoast (talk) 01:36, 4 September 2008 (UTC)

This is the sort of thing someone who is into quantum mysticism would say. Scientifically its crude. Your description is close but even if you described it perfectly its a misapplication of quantum mechanics. The capacity of electrons and protons to quantum tunnel is important to biology and life. It really happens. Atoms (other then hydrogen) are generally too heavy to tunnel in a meaningful way. The larger molecules formed by atoms certainly don't tunnel past each other. Chemical reactions would occur well before any tunneling happened. The person that is made of molecules won't tunnel ever. At least not without the assistance of technology that has yet to be invented or meaningfully imagined. Hope that helps.--OMCV (talk) 02:08, 4 September 2008 (UTC)

That depends on your definition of "in a meaningful way". The diffusion of molecules through solids is in many ways a tunneling process (though there are more factors involved than the tunneling of a single electron). We know from ice cores that something as large as methane will move 10s of centimeters per 100,000 years in ice. Dragons flight (talk) 19:40, 5 September 2008 (UTC)

Roughly speaking, I believe that is true, but it's not millions of years, it's far far more than that. I don't know how to calculate it, but I imagine it's far far longer than the universe will exist (in a state comparable to how it is now, anyway). --Tango (talk) 02:17, 4 September 2008 (UTC)

From what I recall, Brian Greene discusses this in his documentary The Elegant Universe. - 202.168.20.29 (talk) 03:11, 4 September 2008 (UTC)

Gee, Mr. Wizard, I've noted cases where helium or hydrogen passed right through a rubber balloon. Ya fill the balloon, tie it off, and it goes limp in a day. What is the process in those cases? Edison (talk) 04:31, 4 September 2008 (UTC)

That's caused by the rubber being slightly porous, ie. there are lots of tiny holes in it. Helium atoms are very small, so can fit through those holes far easier than the nitrogen and oxygen molecules in air could get out of a regular balloon, which is why helium (not hydrogen unless you were in doing a lab experiment or something - people are not in the habit of button explosive gasses in children's toys!) balloons deflate faster than air ones (you often get them made of foil to stop that). --Tango (talk)

I have had hydrogen in balloons, (yes, lab experiment) and it seems to pass through the rubber faster than helium does. Edison (talk) 18:38, 4 September 2008 (UTC)

H₂ has a molecular mass of 2 grams/mol while He has an atomic mass of 4 grams/mol. Check Kinetic theory#RMS speeds of molecules. Since hydrogen moves faster it collides with the walls more often Kinetic theory#Number of collisions with wall also finding the gaps more often. This principle is the bases of effusion experiments described by Graham's law that are sometimes preformed in pchem classes.--OMCV (talk) 19:16, 4 September 2008 (UTC)

Penis errect in the morning.

Why penis sometime errect in the early morning203.116.34.194 (talk) 05:00, 4 September 2008 (UTC)

See Nocturnal penile tumescence. Kenjibeast (talk) 05:11, 4 September 2008 (UTC)

Drinking water from a bottle of Clorox

Alright, I'm not going to go into why, but I just want to know if there's any way of making an empty bottle of clorox safe to drink water out of. Would a really thorough wash do, or would there still be some sort of nasty residue? Kenjibeast (talk) 05:09, 4 September 2008 (UTC)

Multiple rinses should do the trick. Its the chemical equivalent of washing a nalgene bottle with bleach. In fact bleach bottles used to be choice container for hauling water while climbing El Cap. furthermore adding a small amount of bleach or iodine to stream water is a method killing many of the microbes that might be living in the stream that you don't want living in your GI track. Chances are you will never get the flavor all the way out but you bottles of water will be less likely to grow bacteria. Good luck.--OMCV (talk) 05:45, 4 September 2008 (UTC)

One recommended method of disinfecting water is to add a small amount of household bleach. For details, you might look at the website of the Environmental Protection Agency of the USA.

http://www.epa.gov/ogwdw000/faq/emerg.html

Based on the advice on this website , it seems that an empty bleach bottle, without any further cleaning, is a safe container in which to store drinking water.

(Scented bleach is not recommended.)

Wanderer57 (talk) 05:40, 4 September 2008 (UTC)

I dunno. There are so many other plastic containers out there, I can't imagine why you would be so dead set on a clorox container to bargain with your health. The EPA website is talking about an EMERGENCY, a situation in which the risk of ingesting harmful parasites and bacteria from your water outweighs the dangers of a mild dose of bleach. Also, given that the container is designed to hold bleach and not potable water, the plastic itself might not be optimal (if you're not a fan of BPA anyway). For general drinking purposes, I'd say just find a different container. --Shaggorama (talk) 05:56, 4 September 2008 (UTC)

Allow me to explain myself. It's for a piece of transgressive/postmodern performance art, the legality of which I will have to do some more looking into. However, the main two concerns I know for sure are 1. This act must be safe. as well as 2. A prop is unacceptable, only a legitimate bottle of clorox or similar bleach will suffice. —Preceding unsigned comment added by Kenjibeast (talk • contribs) 06:44, 4 September 2008 (UTC)

How about putting a small amount of water into a clear plastic bag of about the same size as the container, using the weight of that water to slip the bag through the mouth of the container, then filling the bag partway, and anchoring it around the mouth of the container with a rubber band or glue or something? Then, you could drink from it without having the water touch the container? 10:44, 4 September 2008 (UTC) —Preceding unsigned comment added by Scray (talk • contribs)

I think a lot of this is bordering on and surpassing medical advice. We're telling you something is safe based on highly suspicious reasoning about analogs. We're making assumptions about the plastic that bleach bottles are made out of and about the concentrations of bleach. I would seriously take all answers above with some heavy grains of salt. These people are not qualified to make this sort of judgment and their reasoning is extremely dubious. --98.217.8.46 (talk) 12:44, 4 September 2008 (UTC)

Providing the bottle has been thoroughly cleaned and rinsed (just as you would clean and rinse any container used for drinking water) there will be no problem at all. You will need a way of ensuring that only the correct bottle is used in the performance, as a mix-up could have undesirable effects. DuncanHill (talk) 12:49, 4 September 2008 (UTC)

Bleach containers were not designed for holding drinkable beverages. Without checking exactly what the plastic is I'm not sure we can say it's the same as "any contained used for drinking water." I know that in the cases of other chemicals a variety of speciality rinses are used before a given container can be considered to be free of the chemical (in the case of chemical transportation, for example). Again, I would be wary of off-the-cuff advice and analogies with familiar territory unless they are strongly backed up by experience or evidence. --98.217.8.46 (talk) 13:06, 4 September 2008 (UTC)

Household bleach is widely used in the cleaning of food and drink containers and preparation surfaces, and it is inevitable that traces of it remain on those surfaces. The traces which would remain in a thoroughly cleaned and rinsed (I am assuming the questioner has access to ample supplies of potable running water here) would be likely to be insignificant. The container (which is one designed and manufactured for household use by persons having no special training or equipment) is to be used in a performance, not for the long-term storage of water, so the likelihood of harmful quantities of any substances leaching out of the plastic is extremely low. This is not medical advice by any stretch of the imagination, but the OP is welcome to take it as the basis of a risk assessment from someone who has to do loads of the things. The principal risk associated with the activity as far as I can see from the information presented is that the stunt bottle could be confused with other similar bottles in the performance venue, and the props mistress will need to provide adequate controls to prevent this happening. DuncanHill (talk) 13:14, 4 September 2008 (UTC)

Also of interest is the MSDS for Clorox bleach. It provides the concentration of the bleach, the exposure limits, and the appropriate response to ingesting pure bleach. Combined with other reliable information, like the EPA reference above, the OP should be able to reasonably assess the safety of the intended performance. -- Coneslayer (talk) 13:45, 4 September 2008 (UTC)

I just checked the bottom of a Chlorox bottle to see what type of plastic it is. It was labeled with recycling number #2 and HDPE both of which indicate high density polyethylene. In terms of the bottle's plastic it should be no more dangerous than drinking out of a milk bottle and will contain fewer hormones (from the milk). The chemical in bleach are fully water soluble and thus require no special solvent rinses. Besides the chemicals are only toxic at high concentrations (similar to most acids and bases) so the small amount of oxidant left in the plastic to leach into the stored water should do no harm.--OMCV (talk) 13:53, 4 September 2008 (UTC)

Bleaches come in different makes, so I think the plastic bottles can differ as well. – b_jonas 22:16, 6 September 2008 (UTC)

epilepsy / impact on brain

hi! i heard that not only alcohol can damage brain cells but also other abnormal conditions (like orgasms(sic!) and epileptic situations). i further read that psychiatric electro shock (it creates a grand mal situation artifically) not only causes no structural changes in the brain[8] but even lets new brain cells grow[9]... can somebody solve that contradiction for me? thx. ps: there they suggested to ask here... bye. --Homer Landskirty (talk) 05:23, 4 September 2008 (UTC)

Let's hope orgasms aren't an abnormal state of the brain :). The only orgasms that cause brain damage are those associated with erotic asphyxiation, otherwise if someone's had a natural orgasm so strong it caused them brain damage....well, I mean... damn. Way to go! Ask them how they did it and spread the knowledge. As for your comment on EST, if a therapy stimulates new brain cells to grow, that IS a structural change to the brain because new connections (i.e. pathways) are being forged. It's not my understanding that seizures cause brain damage outside the risk of the individual hitting their head or obstructing their airway during the seizure. --Shaggorama (talk) 05:50, 4 September 2008 (UTC)

:-) hm... ok... "structural change" was most likely meant as "structural damage" and they were talking of CT and MRI scans which don't give detailed information on neuron-level... i was always bad in biology, but the high electrical energy in the brain during a seizure seems to be a potential cause for electrolysis (when i held a 9V direct current source into a glass of salt water, it changed its color, although salt and water r quite simple compounds...) and thereby necrosis... but i don't insist that it must be like that... --Homer Landskirty (talk) 06:42, 4 September 2008 (UTC)

My understanding is that prolonged seizure, i.e. status epilepticus, causes brain damage metabolically (through accumulation or depletion of noxious or essential substances, respectively). The electrical energy generated is not extreme and I am pretty sure much lower than that needed to damage human tissue. Scray (talk) 10:35, 4 September 2008 (UTC)

As the amount of elecctrical activity in the brain increases, the voltage present in the brain stays the same. Action potentials are all-or-nothing phenomena. --Shaggorama (talk) 15:30, 4 September 2008 (UTC)

twin universe hypothesis

i have a hypothesis which our spacetime is double sided, while a Big Bang and Big Crunch singularities will be avoided, because my hypothesis is that while one side is empty, the other side is full, and therefore, matter will flow to the other side. which is the Big Bang. And like the inflation theory, the stuff flowing through will accelerate, and in later stages, will start to decelerate. at this time, the other side is shrinking, and this is my Big Crunch. Please give comments. —Preceding unsigned comment added by Superwj5 (talk • contribs) 13:05, 4 September 2008 (UTC)

The reference desk is not a discussion forum, and entries to that effect may be removed. Is there a question here? — Lomn 13:17, 4 September 2008 (UTC)

As Lomn say, this isn't really the right place to ask for comments on an original theory. Even despite that, your description is too vague to make any meaningful comments on. --Tango (talk) 13:24, 4 September 2008 (UTC)

It's very, very easy for anyone to come up with random hypotheses like these - but unless they explain absolutely all of known physics AND explain some unexplained phenomena AND predict some testable thing - they are just useless. Unless your hypothesis is grounded in and backed by an IMMENSE amount of physics, it's about as interesting as your next door neighbors holiday photos. SteveBaker (talk) 19:10, 4 September 2008 (UTC)

"explain absolutely all of known physics" is too high a bar - I think that typically, science settles for "does not contradict any existing known physics and either explains a piece of physics that was previously unexplained or is simpler than other available explanations for what it covers" --Random832 (contribs) 19:20, 4 September 2008 (UTC)

Well, it needs to explain at least as much as the theory it is replacing. It can contradict existing theories, but only if it can explain all the same observations. --Tango (talk) 22:01, 4 September 2008 (UTC)

Yes - exactly. Perhaps I should say that it has to provide convincing explanations for all of the currently observed phenomena for which we already have convincing explanations. Doing that alone would be a pretty amazing thing for a radical new theory of the universe - but the bar to replace current theory has to be that it provides something new - preferably an experiment that could be done that would produce a result that the present state of science would not predict. Perhaps explaining something that's not currently understood - or (I guess) being vastly simpler than existing explanations. But making a testable prediction that turns out to be true is the gold standard.

So, for example, nobody took much notice of Einstein's special relativity until he predicted that the sun's gravity would bend the light of a distant star and that this should be visible in a total solar eclipse. When that experiment was eventually carried out (an interesting story in itself) - and it produced the result that Einstein predicted - the world of science was overturned pretty much overnight. So the theory itself (good though it was) didn't attract much interest until it predicted something amazing.

To produce a counter-example, string theory does a good job of providing an explanation for everything we currently know - but all of the predictions it makes have proven impossible to test experimentally. Some claim that the Large Hadron Collider (LHC) will provide some sort of proof - but the jury is still out on that one. Hence we don't usually treat string theory as "The Truth" in the same way we treat relativity.

SteveBaker (talk) 22:43, 4 September 2008 (UTC)

White hole transformation

today, i read that if the Higgs Mechanism or Superstring Theory is correct, then above a magic energy, matter will become massless. Suddenly, I was reminded of that massless black holes become white holes. I then thought when a black hole mass becomes very small, the Hawking Radiation will set it above the magic energy which it will become a white hole. After some time, the energy will decrease below the magic energy. and in supermassive black holes, the accretion disk will also pull the black hole over the magic energy, and the same thing will happen, except that the accretion disk flies away.Please give comments. —Preceding unsigned comment added by Superwj5 (talk • contribs) 13:13, 4 September 2008 (UTC)

There's a lot of unsupported guesswork in this. Can you cite "magic energy" or this rather unusual definition of a "white hole"? Otherwise there's nothing to this. — Lomn 13:16, 4 September 2008 (UTC)

Massless black holes don't become white holes. White holes have mass just like black holes. Also, white holes don't repel matter, they attract it just like black holes. The classical distinction was that white holes emitted matter and shrank, while black holes absorbed matter and grew; but since Hawking noticed that quantum black holes seem to do both, it's no longer clear what the difference between a black hole and a white hole is.

I don't know much about the Higgs mechanism, but I think it's not governed by a magic energy so much as a magic temperature. It's a phase transition; we're in a "frozen" state of the Higgs field right now, and above a certain temperature it "melts" again. Tiny black holes have very high Hawking temperatures, but I don't think you'd notice weird Higgs effects just because of that. Small sizes and large temperatures are related, and there's probably something weird happening with the Higgs field (and all other fields) at close enough distances to any pointlike particle, like an electron, but we don't see those effects at ordinary distance scales. -- BenRG (talk) 15:08, 4 September 2008 (UTC)

Name of interesting microorganism

I took a really great parasitology course in undergrad but i can't remember for the life of me the name of one of the organisms we went over. I remember the professor was talking about opportunistic infections and fungal pneumonia, and he then proceeded to mention another creature that he said was very distinct in that it was comparable in its morphology to (i think?) a stinging cell on a jellyfish or something along those lines. Does this sound familiar to anyone? Thank you so much!

129.252.70.53 (talk) 13:14, 4 September 2008 (UTC) Timmy

The commonest fungal pneumonias are aspergillosis, coccidioidomycosis, histoplasmosis and blastomycosis. From your description, it sounds like aspergillosis is the most likely. Axl (talk) 19:16, 4 September 2008 (UTC)

I think it possible you're thinking of Pneumocystis jiroveci, previously called Pneumocystis carinii, first thought to be a protozoan but now known to be a yeast-like fungus. On the other hands, stinging cells in jellyfish are "nematocysts", and if you were discussing animal diseases rather than human ones, the most likely candidate is Myxobolus cerebralis, which infects fish by piercing them with polar filaments ejected from nematocyst-like capsules. - Nunh-huh 06:25, 5 September 2008 (UTC)

Human breasts-a store for fat?

How large do breasts have to be to produce the required amount of milk? And if they larger than that minimum, then why? Are they also used as a store for fat? —Preceding unsigned comment added by TrapdoorTrevor (talk • contribs) 13:34, 4 September 2008 (UTC)

Breasts must produce approximately 8 ounces of milk every 3-4 hours during breastfeeding. That is pretty much a single glass of milk. Spread among the two breasts, the required size is noticeable, but not great. It is common for breasts to enlarge beyond the required amount. As for fat, breasts are mostly a store of fat. Men have mammory glands as well, but do not store fat in the breasts as usual as women do. Men usually only store fat in the breasts when fat stores throughout the body are already very full. -- kainaw™ 14:35, 4 September 2008 (UTC)

Sociopaths

Are most sociopaths males? If so, what is the reason for this? --Anilmanohar (talk) 19:02, 4 September 2008 (UTC)

Probably yes. This research thesis gives answers to your second question. Axl ¤ [Talk] 19:50, 4 September 2008 (UTC)

How do you get 'probably yes' out of that abstract? - Lambajan 02:37, 8 September 2008 (UTC)

It's not in the abstract. It's from page 15 of the thesis: "Hare (2003) recommended that a cut score of 30 (out of 40) be used in classifying individuals as psychopaths, and this cut score has been used in research on psychopathy for years. As compared to the 25 to 30% typically found in male offender samples, research indicates that females are significantly less likely than males to be classified as psychopaths when this cut score is utilized. For example, Salekin et al. (1997) found only 16% of 103 female jail inmates met this cut score. Similarly, Warren et al. (2003) reported only 17.4% of 138 female prison inmates met the recommended cut score. Several possible explanations exist for this discrepancy, including an actual gender difference in the prevalence rate or possible biases present in the assessment measure for psychopathy." Axl ¤ [Talk] 18:03, 8 September 2008 (UTC)

That's interesting, thank you. Sorry if I was too harsh. - Lambajan 04:38, 9 September 2008 (UTC)

Not at all. :-) Axl ¤ [Talk] 07:24, 9 September 2008 (UTC)

growing biodiesel in your back garden

I drive a diesel car which does about 40 miles to the gallon, about 100 miles a week - so I need 2.5 gallons of diesel every week. Can you grow that in your back garden? Judging by Jatropha oil, that means you would need one quarter of a hectare in your back garden to run my car completely on jatropha. That is if "A hectare of jatropha produces 1,892 litres of fuel" means per year.

Can anyone tell me if I'm right or not? Is it practical to grow jatropha in your garden?89.240.139.65 (talk) 19:37, 4 September 2008 (UTC)

How long is the growth cycle for jatropha? Assuming you can get only one crop a year, you'd have to produce all the oil you need for the following year at once. So you'd need storage. How is jatropha oil recovered? I know with some other veg oils there significant processing, beyond just the extraction/expellation, to remove impurities, moisture, etc. You might be able to skip these, but excess moisture might lower your yield, and impurities might gum up your engine. I think you could do it for personal satisfaction, but it would be a lot of trouble and not necessarily benefit the environement (if that is your goal). ike9898 (talk) 19:45, 4 September 2008 (UTC)

The storage problem isn't a huge one... he needs only 130 gallons/year. I have 2×275 gallon oil tanks in my basement for heating oil, which is a pretty common setup around here. -- Coneslayer (talk) 20:05, 4 September 2008 (UTC)

You would also need to grow something else like corn to make ethanol or buy methanol. Regardless you need an alcohol to transesterification your bio-oils and produce biodiesel. Next you need means to heat/cool/electrify your home. Then after that we need to do that for our work places. Neat stuff to think about.--OMCV (talk) 20:22, 4 September 2008 (UTC)

I seem to recall hearing that your need a federal permit to grow Jatropha in the United States as it is potentially invasive non-native plant. No idea on whether that is easy to get or hard. You might do better with a locally available alternative of some kind. Dragons flight (talk) 21:31, 4 September 2008 (UTC)

Thanks for the warning about permits - I'm English, so I'll get that checked out with somebody. And I'm sure something like an oil tank could keep the rest of it. Anyone know how long it takes the stuff to grow, if it is one year or not?78.144.169.2 (talk) 22:33, 4 September 2008 (UTC)

Our article Jatropha curcas says "While Jatropha curcas starts yielding from 9–12 months time, the effective yield is obtained only after 2 - 3 years time". yield is also affected by planting pattern, and of course you want a preponderance of female plants. DuncanHill (talk) 22:36, 4 September 2008 (UTC)

Hmmm - interesting! I have 1.2 acres (which is about half a hectare) at the back of my house - and my car also does ~40mpg and I run it 100 miles a week...this sounds rather interesting! I guess the other considerations we need to answer are:

• What amount of water and fertilizer does this stuff need to grow year after year on the same land?
• Would you need to do "crop rotation" and thereby have some years in which you'd get no biodiesel because you'd have to plant nitrogen-fixing plants instead?
• What equipment would you need in order to prepare the soil, plant, weed, fertilize and harvest the stuff? Can you rent it? Borrow it? Share it with neighbors who have the same idea as you?
• How much fuel do those machines require in a typical year?
• What "economies of scale" would you fail to achieve by growing so little of the stuff? Are the numbers you're getting based on planting hundreds of acres?
• Does it grow well in your local climate and soil conditions?
• What pests attack your crop and how can you deal with them?
• What waste products remain after extracting the biofuel (eg bits of the plant that aren't used in the production - left over chemicals - that kind of thing)?
• 130 gallons of Diesel costs maybe $650 in the USA...What is the "opportunity cost"? In other words, what other things could you do with that land and whatever capital you have tied up in equipment that might earn you more than $650?
• How much value to you place on your own labor? Seems like you might spend a LOT of hours ploughing/planting/fertilizing/killing insects/weeding/watering/harvesting/brewing - are you committing yourself to manual labor at less than minimum wage? If so, maybe taking a second job for a couple of weeks a year would be a more profitable use of your time?

Lots to think about...but at first sight, it doesn't sound so attractive. The lack of economy of scale is the problem...if you were planting hundreds of acres then the cost of the equipment and perhaps much of your time/effort would be amortized over a larger amount of product...but at this small scale, you can't afford to buy even a small tractor because it would be idle 50 weeks of the year and wipe out your potential savings for MANY years. Without a tractor, ploughing, planting and harvesting 1.2 acres sounds like back-breaking work for at least several weeks a year.

SteveBaker (talk) 23:18, 4 September 2008 (UTC)

10 inches of rain a year, grows well on poor soils, needs little if any feeding, life expectancy of 40 years so not a lot of ploughing or planting to do, resistant to disease and pests. It sounds, from our article, to be a remarkably easy plant to grow. That said, lots of good points from Steve. As usual! DuncanHill (talk) 23:23, 4 September 2008 (UTC)

Why even grow your oil? Everyone I know who operates converted biodeisel cars get their grease from restaurants. They actually get PAID for their fuel because their fuel source doubles as a waste disposal! And they get to feel good because they're recycling used cooking oil. Just another option to consider. --Shaggorama (talk) 04:36, 5 September 2008 (UTC)

It's OK to a point - but a typical small town can't support more than a few dozen cars that way...there just aren't enough deep fryers being emptied often enough. It's OK as an "I'm alright" solution for an individual - but it's not the way forward for mankind in general. Also, I suspect it's only a matter of time until the McDonald's and the Wendy's of this world start to realize that they could actually charge for this stuff. Right now, they don't because they usually have to pay to have it hauled away - and if someone will take it for nothing - it saves them money. But once there are two or three people hanging around begging them for their left-over oil every day, they may realize that they have a valuable commodity and start selling it. What I suspect MIGHT happen is for them to install the equipment necessary to filter and dry the oil on-site and start filling the tanks of their delivery trucks with the stuff - it would be a GREAT PR thing ("We're going green!") and the whole business of vehicles that burn the stuff smelling like fries could be put to considerable advertising advantage. So while this is a great gimmick - it's hardly going to save the planet and it's only a matter of time until that particular well runs dry for the average motorist. SteveBaker (talk) 05:47, 5 September 2008 (UTC)

OK everybody, thanks for your answers to my questions. You need a big garden to run a car on your own jatropha and at the end of the day, it isn't really practical on a domestic scale for non-green warriors because of processing. If someone was paying you for the right to harvest your garden and process the stuff, it would be great, and then you could buy refined jatropha back from them. Then whoever harvests your garden needs LOTS of gardens to do, and you need to persuade people to give up their lovely gardens as well. Alternative fuels is a fringe business (here at least). In my experience, that means don't jump for it right away, use it in blends. And yes, you can get oil from restaurants, but every little helps (pardon my tesco advert). Imagine the effect if everyone kept just a few jatropha plants, and that would avoid the controversy that the biofuel industry takes precious land from food cultivation.78.149.56.198 (talk) 22:39, 5 September 2008 (UTC)

On another tack, have you thought of approaching your local takeaways offering to remove their cooking oil to recycle as diesel? In my country this perk was proscribed by government bodies only if it were being sold on to others, but okay for personal processing and use. Julia Rossi (talk) 22:35, 11 September 2008 (UTC) Oops, Shaggorama got it. Julia Rossi (talk) 22:38, 11 September 2008 (UTC)

How do a student weight the moon

I'm thinking about how to weight the moon using nothing that a teenager student cannot get hold of. 202.147.44.87 (talk) 23:15, 4 September 2008 (UTC)

Let's assume that you already know the mass of the Earth. From that, Newton's Law of Universal Gravitation, and the equation for uniform circular motion (I'm making the simplifications that (1) the moon's orbit is circular, and (2) the Moon orbits the Earth, rather than both orbiting a common centre of mass), you should be able to get an equation relating the mass, orbital velocity and orbital radius of a satellite. Finding the orbital radius of the moon is a little tricky, but you could probably work it out via a couple of sextants and a parallax argument, and then the sextants will also help you work out its orbital velocity. Not the easiest of projects, but not impossible, either. Confusing Manifestation(Say hi!) 23:48, 4 September 2008 (UTC)

Well, if you knew how much the gravity of the moon affected things on Earth, you'd be able to calculate the mass (not, technically, the "weight"). At first sight, I think you'd need to look at tides - or perhaps the amount the earth wobbles each lunar month because the earth/moon system orbits around a common center that isn't at the center of the earth.

• If the Earth and the Moon weighed the same amount - we'd both be orbiting around a point that would be halfway between the two. But the earth is heavier - so the point about which we both orbit is closer to the center of the earth than the center of the moon. Hence the earth doesn't just rotate on it's axis once a day - it also orbits around that common center once every lunar month. There are probably things you could measure with a telescope that would tell you that...but that's going to require a really accurate telescope - which doesn't sound like something you'd obviously have. This document [10] describes the math - but doesn't explain how you measure the numbers you'd have to plug into the math.
• Measuring the moon's gravity using the effect it has on the tides. You have to be very careful to control for the effect of the Sun's gravity - but in theory, if you know the height of the tide - and you know how far away the moon is, how heavy the earth is...you can figure out the gravity due to the moon - and hence it's mass. The math is in Theory of tides - and it's kinda horrible.
• You'd think (at first sight) that your weight would be less when the moon is directly overhead than when it's beneath your feet - because when it's overhead, it's pulling you upwards and reducing your weight. But sadly, the centrifugal force due to our orbiting around that common center handily cancels that out - which is why we get two high tides each day - one when the moon is overhead and another when it's underfoot. However, you should find a difference between when the moon is directly overhead and when it's at the horizon. It's that difference that accounts for the tides - but perhaps this is a more direct way to measure it - if you have an accurate enough measuring device. Remember, you can't use a beam-balance to do it because the weight of your standard weights is also changing. You'd need a spring balance - or some kind of electronic pressure gauge.

I sure hope there is an easier answer!

SteveBaker (talk) 23:49, 4 September 2008 (UTC)

For what it's worth, Isaac Asimov's book The Double Planet has a chapter on how the moon was weighed. That might be available in used book stores. — Lomn 13:06, 5 September 2008 (UTC)

How about this method:

• Measure the orbital velocity, ω, of the Moon. Its orbital period is about 28 days, so ... let's see ... that's about 2.6x10^-6 radians per second.
• Measure the acceleration due to gravity at the surface of the Earth, g. That's about 10 ms^-2.
• Estimate the radius of the Earth, r_E, using Eratosthenes' method. Let's say that's 6.3x10⁶ m.
• We know that gravitational attraction decreases with the square of distance, so if the Moon is a distance d_M from the centre of the Earth we must have:

$d_{M}\omega ^{2}={\frac {gr_{E}^{2}}{d_{M}^{2}}}\,\Rightarrow \,d_{M}^{3}={\frac {gr_{E}^{2}}{\omega ^{2}}}$

• Plug and chug and we get d_M = 3.9x10⁸ m.
• Measure the angular diameter of the full Moon - that's about half a degree.
• If the Moon subtends half a degree at a distance of 3.9x10⁸ m (neglecting a small correction for the radius of the Earth) then its diameter is 3.9x10⁸ x π / 360 = 3.4x10⁶ m, and so its volume is about 2.1x10¹⁹ m³.
• Assume that the Moon has a similar make-up to the Earth. Measure the density of an average lump of rock, and round this up a bit to allow for higher density towards the centre of the Moon. Let's take an average density of 3,000 kg m^-3. That gives us a mass for the Moon of about 6x10²² kg.

Estimating the radius of the Earth from first principles might stretch a typical teenager, but the rest of the measurements are quite straightforward. Gandalf61 (talk) 13:14, 5 September 2008 (UTC)

You were doing great right up to the point where you assumed the density of the moon. There is no reason to assume that moon rocks have the same kind of density as earth rocks or that the density profile is anywhere near similar to what we know for the earth. The earth has a liquid nickel/iron core - the moon almost certainly doesn't. (And if we cheat and look it up - we find that the earth is nearly twice as dense as the moon...but that's cheating because we're not doing an experiment). The guesstimate you came up with happens to be within 10% of the true number - but that's just luck. If you'd used the same guess to estimate the density of the earth - you'd have been off by a factor of around 2. The problem with weighing the moon is precisely that we DON'T a-priori know it's density. We have to figure it's mass some other way (tides - for example) and use that with our size measurement to deduce a density. SteveBaker (talk) 15:59, 5 September 2008 (UTC)

Yes, the tidal method avoids making assumptions about the make-up of the Moon. However, it only gives you the ratio of the Moon's mass to the Earth's mass. To derive the Moon's mass you need to know the Earth's mass, or equivalently its average density. Asking a student to measure the Earth's mass or density to an accuracy of better than a factor of 2 is quite a tough challenge - they would need to perform a backyard version of the Cavendish experiment. Gandalf61 (talk) 09:34, 6 September 2008 (UTC)

Why is measuring the mass of the earth so tough? We can easily measure g to high precision (stopwatch, rock, tall building) - so we can figure the mass from Newton's law of Gravitation - all we need to know for that is the radius of the Earth. That's obtainable by Eratosthenes method. (And your proposed approach requires us to do that too!)...you can get pretty good precision with Eratosthenes using two tall buildings, two students in different cities with cellphones and tape measures. SteveBaker (talk) 13:37, 6 September 2008 (UTC)

Well, yes, it's easy to determine GM for the Earth by various means. The hard part is determining G at all accurately. If you just give that to the students, then you've done most of the work for them. Algebraist 14:04, 6 September 2008 (UTC)

Indeed. Measuring g and r_E only gives you the product GM_E. It wasn't until the 18th century that G or M_E (or, equivalently, the average density of the Earth) could be measured separately with any degree of accuracy. In 1774 Nevil Maskelyne measured the gravitational attraction of Schiehallion and estimated the average density of the Earth to be 4.5 g cm^-3 - and this took seven weeks of detailed surveying [11]. In 1797/8 Cavendish used John Michell's torsion balance method to get a more accurate value of 5.45 g cm^-3, but this required making very precise measurements. Gandalf61 (talk) 14:54, 6 September 2008 (UTC)

Portion of agriculturally usable land on the surface of the globe

It is said that 29% of the earth's surface is covered by the land mass. What portion of the total surface is usable for agriculture for growing food? 86.33.247.155 (talk) 23:30, 4 September 2008 (UTC)

Agriculture says "Livestock production occupies 70% of all land used for agriculture, or 30% of the land surface of the planet." - so, if I read that right, livestock agriculture covers 30% of all land - and that's 70% of agricultural land. Overall then, there must be more like 43% of all land under agriculture...which is maybe 11% or so of the earth's surface. That number seems high to me - but that's what the article says. It references a UN report - but the link has gone bad - so I can't see the original source. SteveBaker (talk) 00:05, 5 September 2008 (UTC)

That quote says "used", the OP says "usable". There is presumably some unused but usable land (although perhaps not much). --Tango (talk) 00:27, 5 September 2008 (UTC)

Yep. I think it's pretty debatable as to what's "usable" - I mean we COULD erect giant pressurized, heated greenhouses over the summit of Mt Everest - bring in a few feet of dirt and plant stuff right on the top - it's technologically quite possible - but you wouldn't normally say that the summit of Everest was "usable agricultural land". So where do you place your limits? Usable "with what degree of difficulty" is the real question. When you see how (for example) the Dutch reclaimed ocean-bottom with relatively crude windmill pumps - and now they intensively farm it. That's arguably a lot harder than farming Mt Everest so it would be rash to disallow any region on the grounds of technological difficulties - and the way people are steadily mowing down the Amazon rainforest for crops - you can't even ask what we sensibly should farm. We even do agriculture out in the oceans with fish farms - so it's impossible to know what limits to place on such a question. But 11% is evidently what we actually "do" farm. If we're asking what could 'easily' be farmed or 'easily and sensibly and legally' - then I suspect we're already beyond that limit. SteveBaker (talk) 05:06, 5 September 2008 (UTC)

September 5

"base SI quantity"

I have the question: When using the words "base SI quantity for 3mg," would I be referring to "mass", or "gram"? No wiki article exists on Base SI quantity, and as and American trying to learn more about SI, this is somewhat confusing. Thanks, Spencer^T♦C 00:28, 5 September 2008 (UTC)

I don't know about "base SI quantity" but SI base units may be what you are looking for. DuncanHill (talk) 00:41, 5 September 2008 (UTC)

Oh wow, I feel stupid. Thank you very much. Spencer^T♦C 00:42, 5 September 2008 (UTC)

No need to feel stupid (everyone finds new systems of measurement difficult at first), and I am glad to be of help. DuncanHill (talk) 00:44, 5 September 2008 (UTC)

:D. Spencer^T♦C 00:45, 5 September 2008 (UTC)

By the way, the SI unit of mass is the kilogram, not the gram (don't ask me why...). --Tango (talk) 00:51, 5 September 2008 (UTC)

We did use the gram for a while - in the CGS (centimeter/gram/second) system. Now we use the MKS (meter/kilogram/second) system instead (well, strictly "SI" - which is MKS + moles, amps, candelas and kelvins). CGS was very gradually phased out from about 1880 until fairly recently (some fields still use CGS - electrodynamics being the most notoriously stubborn). Mostly because for most practical purposes the resulting numbers tended to get too big in most fields of human-scale things. It's unfortunate that we stuck with 'gram' and therefore ended up with a 'kilo' prefix on a 'base' unit - it would have been nicer if we'd just had some new unit that happened to be the same size as a thousand grams. But that's history - and we're kinda stuck with it. SteveBaker (talk) 04:54, 5 September 2008 (UTC)

I added a redirect so that it is easier to find for the next person who ties this name. Graeme Bartlett (talk) 01:44, 5 September 2008 (UTC)

Gravity question

All humans are attracted to the center of the earth by gravity. So if there was a hole drilled from the north pole threw to the south pole and I fell down it, would I end up in the middle of the earth? —Preceding unsigned comment added by 1000kA (talk • contribs) 00:45, 5 September 2008 (UTC)

Ignoring the fact that such a hole is impossible, yes. You would be weightless at the centre, since the gravity from all the matter surrounding you would cancel out. --Tango (talk) 00:52, 5 September 2008 (UTC)

Well, yes, you would get to the centre, but you would be moving very fast by the time you got there. After passing the centre, gravity would start to slow you down again, and (ignoring various things) you would end up oscillating about the centre. If we're not ignoring air resistance, then you'd end up in the centre after bouncing back and forth a bit. Algebraist 01:16, 5 September 2008 (UTC)

You'd keep bouncing as the gravity of Earth would be cancelled out, but the moon (which is powerful enough for tidal effects) would still be tugging at you - as would a weak tug from the sun which changes relative direction with your orientation to Earth as Earth spins. -- kainaw™ 01:20, 5 September 2008 (UTC)

In the pole to pole hole there would be no Coriolis force as you would get from any other places on the earth. Also the air pressure and temperature would be so high down deep, that the air would be liquid and you would be baked on the way down. Graeme Bartlett (talk) 01:48, 5 September 2008 (UTC)

Dont you mean boiled? —Preceding unsigned comment added by 1000kA (talk • contribs) 02:01, 5 September 2008 (UTC)

An interesting side note: ignoring friction etc., the time to "fall" through a straight hole between any two points on the surface of the Earth is the same as for any other two points. Saintrain (talk) 13:03, 5 September 2008 (UTC)

Darn, you beat me to it. Indeed, if you pretend the Earth is a solid non-rotating sphere of uniform density, and dig a straight shaft between any two points on the surface, and lay down frictionless rails on the bottom of the shaft, and evacuate the tube so there's no air friction, and put a train car on the rails, and let gravity do the rest, it will take you from one end of the shaft to the other in a time of $\pi {\sqrt {\frac {r_{\text{earth}}}{g_{\text{surface}}}}}$, which is about 42 minutes, independent of the endpoints. I think the acceleration you feel is also constant throughout the trip, and equal to ${\frac {r_{\text{min}}}{r_{\text{earth}}}}g_{\text{surface}}$, where $r_{\text{min}}$ is the minimum distance from the tube to the center of the Earth. (This is the acceleration that would be measured by an accelerometer that you took on the trip, which is not the same as your acceleration with respect to the rest frame of the Earth.) On a trip from San Francisco to London you'd feel about 0.78 g. I could live with that. Pretty expensive public works project, though. -- BenRG (talk) 14:19, 5 September 2008 (UTC)

I don't see how acceleration could be constant. When you start, you're at the surface, so that's 1g, in the middle you are somewhere beneath the surface, so that's less than 1g (0g if you're going between antipodal points). --Tango (talk) 18:18, 5 September 2008 (UTC)

In the case of the antipodal points, you're in free fall the whole time, and therefore feel zero g, in the sense that if you carried an accelerometer with you, it would register zero g. 1000kA, if there's enough pressure to liquefy air, there's going to be enough to keep water liquid, if not solidify it. — DanielLC 22:28, 5 September 2008 (UTC)

Mars

I have seen many pictures of mars taken over the years where abnormal structures can be clearly seen (pyramid type things among others). I would like to know why these structures have not been scientifically investigated and why NASA has not sent a probe to these interesting areas? Eg: the face on mars. If you are wondering what I’m talking about search youtube for “structures on mars” There are also areas of photos that have been clearly airbrushed, what do NASA have to hide? 203.202.144.223 (talk) 00:48, 5 September 2008 (UTC)

Please read Apophenia and Pareidolia. — BRIAN0918 • 2008-09-06 18:06Z

Have you tried reading about the "Face on Mars" here? DuncanHill (talk) 00:50, 5 September 2008 (UTC)

I have read about the face on mars as an optical illusion, however i have also read that the recent pictures were had been harshly (and unnecessarily) filtered. But there are many other pictures showing other odd things other then the 'face on mars'. I guess another question I have is why would NASA airbrush pictures of mars' surface? 203.202.144.223 (talk) 01:00, 5 September 2008 (UTC)

Another question would be why someone would want NASA, heavily funded by tax dollars, to waste money exploring ideas from some crackpots who know nothing about Mars except what they've seen in video games and science fiction shows? If the crackpots want to investigate all those artificial structures, then let them raise the money to do so. NASA is busy trying to find an optimal location for a sustainable living area should we achieve manned missions to the Mars. -- kainaw™ 01:18, 5 September 2008 (UTC)

So you do believe that those structures are artificial? Even at the minute chance they are artificial wouldn’t that be reason enough to at least investigate them? Or hey, maybe that’s just some crazy opinion of a “crackpot” 203.202.144.223 (talk) 01:40, 5 September 2008 (UTC)

This is one of those "please prove that something doesn't exist" arguments. The crackpots want proof that there are no artificial structures on Mars. If we brought Mars to earth, rock by rock, and examined the entire planet, they would still be claiming the overlooked something. It is a project that has no end and, therefore, would take forever and cost an infinite amount of money and man-hours to complete. So, the answer is a simple no. It is not worth wasting all our money and time on something that has already been examined and has already been proven to all sane people to not exist, but still gives crackpots a big fuzzy feeling when the send their little "NASA is covering this up" messages back and forth on the Internet. -- kainaw™ 01:55, 5 September 2008 (UTC)

Looking past the other issues, it is also impractical at current. After travelling 150 million kilometers, the mars landers come down with a targetting precision of +/- 50 km. I suspect that visiting most "structures" you'd like to look at would be challenging if your starting point is only good to within 50 km. Dragons flight (talk) 02:09, 5 September 2008 (UTC)

Sad, but true - these things are worth a quick check - and NASA have done that. In the case of the "face" they took higher resolution photos - which look NOTHING like a face. They apply an appropriate amount of diligence - but once they've proved to a reasonable degree of certainty that nothing interesting or unusual is going on, they drop it.

Sadly, the nut-jobs on the conspiracy sites simply won't ever give up their crackpot ideas. Check out the "The moon landings were faked" loonies...we have a freaking great HUGE pile of moon rocks in a lab in Houston - I've seen them. There is even a moon rock that you can actually touch. We have movies that can't be faked without genuine low gravity conditions. We have retroreflectors on the moon that you can bounce lasers off of that prove we put man made stuff there. We have brave, honest men with no history of lying or conspiracy who tell us what it was like to be there. We have literally tens of thousands of people who would have all have to have agreed to the conspiracy - and NOT ONE of them has ever confessed to lying or concealing the truth - not even on their death-beds. We have really solid counter-arguments to absolutely every single complaint the crackpots put up...but still, I don't believe that we've ever convinced a single one of them. It's fair enough that you might come up with some strange things you see in those photos (non-parallel shadows, no stars in the photos, etc). But when I successfully explain all of them, you need to say "Oh! Well, then you must be right." - you don't go back, find ANOTHER dozen tenuous things - let me explain those, then find ANOTHER dozen (even more tenuous) things.

There is no way to get rid of these people - no amount of proof will ever make them believe. Would you believe there are still flat-earth believers? Yep - there is an entire web site full of them. You say - but there are guys up there in orbit right now looking down at the earth and they say it's round. They say "So have YOU ever seen that?...Then how do you know?"...then an actual astronaut who HAS been there and seen it says "Yes! I've seen it with my own eyes."...and they say "Ah - but it was an optical illusion due to refraction of light though the atmosphere"...and you say "But refraction bends light in the opposite direction"...and they say "Sure it does in the lab - but have you tested that in the upper atmosphere?". You say "But what about ships disappearing over the horizon?"...and they say "Ah - diffraction through the atmosphere" - and you say "But diffraction bends light the other way...and you just AGREED that it works my way"...and they'll say "But the water vapor alters the sign of the pseudo-magnetic wibble matrix because of quantum grungology and that's why it does it."...and off we go again.

It's an eternal regression - they can come up with crazy crackpot special-case exceptions and toss in random pseudo-scientific babble no matter what. When you do knock down their arguments - they ignore that and move on to an even crazier claim. They pretty much universally don't understand enough science to comprehend why your counter-arguments are valid.

At some point, you have to say "You're an idiot." and move on...doubly so if you are a government funded agency who will get in deep trouble if you spend a few megabucks on proving some crackpot wrong.

So - the 'features' on Mars are no different from seeing bunny rabbits in the clouds. The human visual system has a built-in feature that forces you to try to find pattern in anything you see. Most of the time, this is useful - but sometimes it makes you see faces on Mars, bunnies in clouds, and allows small children to scare themselves silly at bedtime by seeing monsters - which turn out to be shadows cast by toys or whatever.

You can keep on demanding more and more proof - but there comes a point when you're going to be labelled a "crackpot" - and with good justification! Science requires us to observe (We see a face on Mars!) then it requires us to consider the likelyhood that this observation is a meaningful thing - (What are the odds that there is really an artificial construct on another planet? What are the odds that this is just a "cloud bunny"?) - if we conclude that the odds are good enough that there is something really going on - we investigate (we move a Mars observation satellite over the feature and we take a much better photo) - when we find we were wrong, we give it up. We don't go on and on banging on about the same thing. There are much more interesting things to do with our big, clever brains.

SteveBaker (talk) 02:31, 5 September 2008 (UTC)

Thankyou Steve, I appreciate your detailed response. And I am also quite interested these “cloud bunnies” you speak of :p . But in all seriousness going back to my earlier question: (Now I am not asking this as some sort of conspiracy nut as there could be a valid answer) why would it appear that NASA has airbrushed photos of mars’ surface? Going through many pictures including the more recent ones I have come across, i have found a lot of them which appear to have been blurred in specific areas. 203.202.144.223 (talk) 02:56, 5 September 2008 (UTC)

Give me an example. It's hard to argue without being able to see the image you're talking about. Note that NASA's imaging folks are REALLY good. If they wanted to hide something - they'd do a bang-up undetectable photoshop job and you'd never know you'd been fooled. Heck - I can do that easily enough. Look at this photo: [12] - it looks OK - right? Well, in reality, the cute puppy on the right had fought like crazy to avoid being photographed looking cute and had scratched my arm so badly I was bleeding from two 3" long cuts. Two minutes with a good image editor - and you'd NEVER know. So why "obviously" airbrush something and arouse suspicion? But show me the photo. SteveBaker (talk) 04:15, 5 September 2008 (UTC)

Example will be on it's way as soon as i get home from work. Damn you restricted internet access!! 203.202.144.223 (talk) 04:53, 5 September 2008 (UTC)

One reason I know of off-hand is that NASA will typically composite together several photos from a spacecraft in orbit. Because the planet is curved and the picture is flat - the photos don't quite line up properly. Also, one photo may be taken several orbits after the other - and the planet rotated in the meantime - so the sun moved a bit in the local sky and shadows moved a bit. The quick/cheesy way to fix that is to blend together the two images along the seam. The slight mismatch shows up as a blur. It's worse where four photos meet at a corner - so that could explain some blurry patches. You can see this happen in places in Google Maps also. However, there may be other reasons...lets' examine an actual 'suspect' photo. SteveBaker (talk) 05:36, 5 September 2008 (UTC)

check these out: LINK ---> [13]

LINK ---> [14] —Preceding unsigned comment added by 61.68.212.191 (talk) 09:15, 5 September 2008 (UTC)

Wow, it's sooo clearly an alien civilization, and not just a bunch of rocks. :-P I mean seriously. This some stretch of the freakin' imagination. --98.217.8.46 (talk) 11:54, 5 September 2008 (UTC)

The pale crater is simple jpg or digital artefacts from the way the pictures are taken the colour depth is not very high and so you end up by pixles which have a different colour than the next one so you se squares, which are no houses, but look like houses for people who have no knowledge on ditigital images. ---Stone (talk) 13:05, 5 September 2008 (UTC)

The hires video from the samples introduced into the TEGA instrument on the other video is great!! I taked to a scientist working on the project and he said that they had great pain because they where not able to get the sticky mars soil through that screen. This is a test of the groundsupport equipment filmed with a camera held next to the robotic arm. The pictures the robotic arm camera is able to take I have seen for myself here in the house and they are black and white and not that reolution at all. There is no camera on mars capable to make avideo like that. Keller the PI of the RAC would have like to have one, but he has not! So the NASA has no such hires videos at all!--Stone (talk) 13:05, 5 September 2008 (UTC)

The thing I find sad about these kinds of conspiracy theorists (and YE creationists, too), is that there is so much *real* wonder and beauty in the natural world, and they ignore it all to focus on these wobbly figments. I mean, there are shrimp that shoot fish with sonic pistols, and these guys are still nattering on about the moon landing 40 years ago! We should pass a law that anyone who has actually walked on the moon can punch these guys in the face whenever they like. --Sean 14:58, 5 September 2008 (UTC)

So - the moron in the video spends FIVE MINUTES to impart ONE URL (click here - then click here - then click here...OH FOR CHRISSAKES! Just tell me the URL already!). That guy is surely fond of his own voice. Then he takes the image and boosts gain until the underlying JPEG artifacts are visible and spends another FIVE MINUTES pontificating about the amazing "roads" and "buildings" he can see. He's looking at regular shaped features in the lowest couple of bits of an approximated image. Here are some ground-rules:

• Rule 1: Don't EVER do image analysis on JPG images - or images that have EVER been stored in JPG format. You need the original TIFF images that were never compressed with a lossy algorithm. In order to save space, the JPEG algorithm discards information that the un-assisted human eye can't resolve. It approximates colors and introduces "blocky" structure in the image. When you view it at normal resolution and normal brightness on a typical display - you don't really notice the errors it introduces - so it's a great way to make porn take up less space. When it matters - YOU DON'T USE JPEG! When you start messing with the brightness, contrast, zoom or anything else, you'll expose data that was deleted by JPEG in order to save space - and untrained idiots like that moron in the video will start to see...whatever they want to see. The joke is that they're looking at deleted data!

• Rule 2: Any image feature that is aligned with the raster pattern of the image is highly suspect - maybe a camera issue - maybe a compression issue. Features that aren't aligned with the raster are much more likely to be "real".

• Rule 3: Serious experts don't post shakey camera-pointed-at-CRT videos to You Tube. They write papers and present them clearly on nicely formatted web pages. People who are fond of their own voices spend five minutes making themselves sound like experts when in reality they are too dumb to read off the image's URL off the goddamn screen!

Please - don't waste our time with this kind of crap.

SteveBaker (talk) 15:38, 5 September 2008 (UTC)

Metric System

why united states has been slow in adopting the metric system? —Preceding unsigned comment added by Christianlazaro (talk • contribs) 03:41, 5 September 2008 (UTC)

Mostly I think it's a lack of incentive. It's an expensive process. The UK more or less did it - but it took 40 years and things were very messy along the way. It's not just a matter of saying "Now switch over!". Consider just one industry - house-building - you have things like the sizes of wood from which houses are made is a "two by four" - two inches by four inches. But you call that a 5cm x 10cm - then you have an error - it's really 5.08cm x 10.16cm. But having 5.08x10.16cm wood in all of your stores isn't REALLY converting to the metric system - it's just calling things by different names. But you can't suddenly start have sawmills start selling "true" 5cmx10cm wood because it won't fit the door frames and metal tie pieces and so forth - the entire building industry would have to redesign absolutely every component - from wood to nails and screws, pipes, tools, everything! Worse still, 2x4's aren't REALLY 2" x 4" - they start out life as that - but are actually smaller when they are planed smooth. So you have an entire industry based around some rather arbitary sized thing. You can't turn that around overnight because people would still need the old-style sizes in order to repair existing structures. Doors have to fit into door frames. You couldn't expect stores to stock twice as much stuff - half metric and half old-style.

Things go deeper than that. In medicine the Americans use "grains" as their unit of weight for pills and such. The abbreviation for "grain" is "g" - which is the same as "gram"...which is the traditional unit for drugs in the metric world. Now you have to administer a change-over period in which tens of thousands of patients are at terrible risk of being over-dosed or under-dosed.

It's VERY tough. The UK only did it because the rest of the Europeans had already done it - and joining the European community was the way ahead. The US have no such problem.

SteveBaker (talk) 05:18, 5 September 2008 (UTC)

See Metrication in the United States. Metrication in the UK is far from complete; see Metrication in the United Kingdom.--Shantavira|^{feed me} 07:45, 5 September 2008 (UTC)

Technically, the entire U.S. systems is based on the metric system, anyway -- it's just that the ordinary person doesn't know and doesn't care.

The U.S. is a large country; its two largest neighbors, Canada and Mexico, have little influence on how things work inside the U.S. And, as far as that goes, in Canada everyday measures like road-sign distance (in kilometers) or gasoline volume (in liters) have only been metric for 30 years.

As with Canada, where there was also great resistance to the switch, the U.S. will gradually shift.

This is an example of how technological innovation works: it's easier to change when you're not dragging a whole lot of infrastructure. In 1955, nearly 83% of Swedes opposed the idea of a switch from driving on the left to driving on the right, though the change did take place on Sept. 3, 1967 (happy belated anniversary, Dagen H). --- OtherDave (talk) 10:50, 5 September 2008 (UTC)

I can't begin to imagine how bad that must have been - if you drive a car on the side of the road for which it was not designed - then overtaking on a two- or three-lane road becomes a lethally dangerous activity. I've driven my (British) right-hand drive car in France - and I have a right-hand drive car here in Texas too (although I don't drive it on the roads much) so I've done this a bunch of times. Overtaking is a really dangerous thing because you have to pull all the way out into the oncoming traffic's lane before you can see what's coming. Even on a multilane road, pulling out from behind a big truck is dangerous if there is a vehicle in the outside lane is going really slowly for some reason. The Swedes must have known this going into it - but I wonder how many people died for that change before the majority of old "wrong side" cars were finally off the roads?

One problem with metrication is that you've got to start educating people into the metric system from way before you start using it. In the UK, I was in the first group of kids to be taught both systems in parallel - that would have been in the early 1960's - so the education process started a good 10 years before the switch began...and the switch is still going on today! More confusing still - we Brit's also changed our currency from it's old mixture of base-12 and base-20 counting to a decimal system around the same time. That wasn't such a horrible mess though - the switch was actually completed a few years ahead of schedule.

As our article says - just the cost of replacing two million road signs (it would be a hell of a lot more than that here in the USA) is frightening. It's not just the cost of making the signs - you have the cost of installing them - and the difficulty of finding them all! Since existing signs typically round distances to the nearest quarter mile for junctions and to the nearest mile for longer distances - you can't simply convert the miles indicated on the old sign into kilometers and round off the result - because the sum of the two round-off errors could add up to a more-than-1km error in the finished sign. You'd have to go out there and re-measure the distances...and in some cases, reposition the signs pole/gantry. You could easily spend several billions of dollars on that alone. SteveBaker (talk) 11:39, 5 September 2008 (UTC)

For what it's worth, according to Dagen H, most Swedes had left-hand drive cars before the switch, which did cause more accidents, and that was one of the arguments for the switch. I suppose there would be at least minor health and safety benefits to having a single system of units in use throughout the world. It would have saved the Mars Climate Orbiter. :-( -- BenRG (talk) 14:59, 5 September 2008 (UTC)

Just to clarify something SteveBaker brought up in his first reply. We have 2x4's in Canada and that's what we call them. We've never "converted" them to anything else. In a way, building materials like that are the easiest to change because the 2" by 4" is unreal (to the end user) to begin with. Canadians call them 2x4s, we just don't call them 2 inches by 4 inches and the problem goes away. I don't think anyone suggests that switching to metric would be a simple thing for the US, but many of the concerns I've read are more hand-wringing than anything else. Afraid grams and grains might be confused? Then do what we did and use milligrams instead of grams. Don't want to remeasure all your roadways? Then don't and just have them precise (1.7km to next exit) and relocate them later if you really want to. Matt Deres (talk) 12:54, 5 September 2008 (UTC)

To clarify further, a 2x4 isn't 2 in. by 4 in. anyway, at least not when you buy it. Dimensional lumber says it is actually approximately 1+1⁄2 in × 3+1⁄2 in (38 mm × 89 mm) "due to planing and shrinkage as the board is dried." -- 128.104.112.147 (talk) 19:21, 5 September 2008 (UTC) Whoops - just noticed Steve already said that.

Just so we're clear, the UK metrification-process is a lesson in how not to metrify. We measure distance in miles (there was no big switch over of signs), sell petrol in litres, but measure fuel economy in miles per gallon. (As with everything, we have to give the metric equivalent as well, but no one could tell you whether, for example, 10km/litre was good or bad. I certainly couldn't. We also have our own 'british' gallon which 90% of people couldn't convert to a US-one. Or litres for that matter). We measure ourselves in pounds (and stone) but the doctor (and our gym) will ask for our weight in Kg.Similarly, i conducted my whole education in metric (up to and including a maths degree), but couldn't tell you intuitively how tall someone was without using imperial. I would love nothing better than to go fully metric but it just won't happen until a couple more generations. Maybe as americans are generally less parochial and twee they might find it easier adapting. 82.22.4.63 (talk) 17:08, 5 September 2008 (UTC)

Thanks for the clarification; I'm laughing at the notion of gas sold by the liter but used as mpg. I know that Canada used the imperial gallon, a source of endless confusion to Americans even in pre-metric days (along with the strange-colored money and that peculiar letter at the end of the alphabet). For most people, the late Thomas Gilbert thought that learning conversion math was pointless. He developed mnemonics -- e.g., for the temperature outside -- "20 is plenty; 25, swim and dive" -- because in that setting, you just want do know if you need a coat (or gloves, or a swimsuit). --- 22:26, 5 September 2008 (UTC) —Preceding unsigned comment added by OtherDave (talk • contribs)

Replying to SteveBaker's first reply: I'm surprised at you, Steve. You say a 2 x 4 is "really 5.08cm x 10.16cm". NO IT IS NOT! That is an elementary error which scientifically illiterate people often make, but I didn't expect to see you introducing spurious accuracy. 2" x 4" is 5cm x 10cm. 5.08cm x 10.16cm is the equivalent of 2.00" x 4.00". I might just about accept millimetre accuracy for wood, but not .1mm. (In fact, for some reason we get 47mm x 100m - see for example [15]. --ColinFine (talk) 22:00, 8 September 2008 (UTC)

100m? I think that you mean 100mm. Axl ¤ [Talk] 19:53, 11 September 2008 (UTC)

Why do celestial bodies spin and/or move in a circular motion?

Planets, suns, even entire galaxies all spin and/or move in a circle, and never stop. Why is this? What is causing this momentum? Stranger still,- all tiny bodies (atoms, electrons, etc.) seem to have this quality. Why only the very small and the very big? Now technically an electron doesn't revolve around the nucleus, but it is a useful way of thinking about it, and it's close eneough to make my point here. Anyways, it seems odd that here at our medium mass perspective nothing seems to spin on its own.Hey, I'm Just Curious (talk) 04:09, 5 September 2008 (UTC)

Well, technically, they move in ellipses - not necessarily circles. But the reason is this: If there is no friction and no air resistance then there is nothing to stop the object from moving (any object - not just suns and moons and such). Newtons' laws of motion say that if there are no forces acting on an object, it'll travel in a straight line at constant speed forever. Here on earth, it's just about impossible to get rid of the friction and air resistance - so we tend to have the "gut feel" that objects ought to slow down and stop eventually - but that's not how the universe works. So that's why they keep moving forever.

Why they travel in elliptical/circular orbits is because of gravity. Throw a rock in a dead straight line towards the horizon and it'll start maybe four feet off the ground and arc downwards in a parabola and hit the ground a few feet in front of you. Throw it a bit harder - and it'll go further forwards before it hits the ground. Now - the earth is curved - so if you throw the object REALLY hard (actually a lot harder than you could ever really throw it) - it would go so far forwards that by the time it had fallen four feet, the earth would have curved away beneath it by MORE than four feet. Instead of getting closer to the ground, it would shoot off - getting higher and higher above the ground until eventually, it ends up in space. If you throw it at EXACTLY the right speed, the rate at which it falls would EXACTLY match the rate at which the curvature of the earth causes the ground to fall away beneath it. So in the time it falls 4 feet - it would have travelled so far towards the horizon that the ground was exactly four feet lower - when it falls four more feet - the ground fell away four feet more than that. It would NEVER hit the ground! If there were no air resistance - it would "fall" around the earth forever travelling in a perfect circle. That's an "orbit". So the moon (for example) is just like your rock - it's travelling so fast around the earth that it falls exactly fast enough to avoid hurtling off into space and to avoid hitting the earth. The exact same thing happens as the earth goes around the sun - or the sun goes around the galactic core. So this is how you get perfectly circular orbits.

What happens in space if the object is going just a little bit too slow to stay up in a circular orbit? Well, that's the kind of thing that happens with comets. They aren't going quite fast enough to stay in a perfect circle - so they start to fall closer to the sun. But as they fall for so long (years!) they gradually speed up - and when they get going fast enough, they are going too fast to stay in a circular orbit - so they swing around the sun and shoot off outwards again. Now the sun's gravity is slowing them down - so they go slower and slower until they start falling back towards the sun. They keep this up pretty much forever - orbiting in huge ellipses.

The idea that electrons are little "planets" orbiting the atoms nucleus "sun" is flat out WRONG - it was thought to be true a hundred years ago - and it was (lamentably) still taught in schools in Texas as recently as a couple of years ago - but it's WRONG! So forget that. An electron is a tough thing to pin down - you never really know exactly where it is because in some sense, it isn't in just one place. There is a "probability cloud" - imagine a fuzzy ball of "maybe there is an electron here"-ness surrounding the nucleus. Hence there is no similarity and the question can be "un-asked" rather than answered.

The reason things at "human scale" don't ever seem to keep moving forever is simply that we live in an environment that's full of gas and rough surfaces. Friction and air resistance are absolutely everywhere humans live - so nothing seems to be obeying Newton's laws (they are - but the friction and air resistance apply forces to them). But the guys in the International Space Station are only too familiar with things that move essentially forever. Their home up there is doing exactly that. (Although there is still a teeny-tiny amount of air up there at 300 miles above the earth - so there is still a teeny-tiny bit of air resistance and eventually it would fall back to earth if we left it alone. Hence, each passing Space Shuttle or Russian resupply ship gives it a bit of a nudge to keep it going - and it has some small engines of it's own that could be used for the same thing.

If we were peculiar aliens who lived in deep space without need for air - we'd be surprised that on Earth everything slows down and stops.

SteveBaker (talk) 04:32, 5 September 2008 (UTC)

Pump Stalling Phenomenon

What is the pump stalling phenomenon in case of centrifugal pumps as well as positive displacement pumps?--Ashish V. Kulkarni 05:40, 5 September 2008 (UTC) 05:11, 5 September 2008 (UTC) —Preceding unsigned comment added by Ashishkulk (talk • contribs) 04:55, 5 September 2008 (UTC)

There are two ways that a pump can stall. Assuming a pumping a liquid:

1. if the input is restricted enough the reduced pressure inside the pump will cause cavitation;
2. if the output is blocked, a positive displacement pump will stop. Saintrain (talk) 13:34, 5 September 2008 (UTC)

A positive displacement pump should always have a relief valve in the output ahead of wherever a valve could restrict flow, to prevent breaking the pump or bursting a pipe. Positive displacement usually means the liquid flows or something breaks, beyond merely stalling.Edison (talk) 15:00, 5 September 2008 (UTC)

Cavitation can also occur when you are using the pump at the top of a pipe to pull liquid up too great a vertical height - the maximum height you can pump water that way is about 32 feet for example. Similarly - the output doesn't have to be blocked (even partially) to stall the pump - there could simply be too much output pressure due to the height the liquid has to be pumped. SteveBaker (talk) 12:32, 6 September 2008 (UTC)

sound waves

1. Strike one of the tuning forks with a rubber mallet or the bottom of a rubber soled shoe. Do not hit the tuning fork on a hard surface, doing so, may damage the tuning fork. Listen to the sound. Now press a button on the telephone and listen to the sound generated through the earpiece. Which sound do you think is more complex? Explain your answer. 2. Compared to the tuning fork and the telephone dialer, is the sound of a person humming, a simple or a complex sound. 3. Try pressing the buttons on the telephone dialer. Can you observe any order to the tones? Does the pitch get higher or lower for larger numbers, or does it seem to be random. 4. How do you think the phone company recognizes the numbers that you dial? —Preceding unsigned comment added by 124.43.195.66 (talk) 05:03, 5 September 2008 (UTC)

Please do your own homework. However, you might want to review harmonics. --Kjoonlee 05:09, 5 September 2008 (UTC)

You can answer this question yourself by following the instructions given to you by your lab (i.e. the instructions you give us). The question is asking for your opinions and observations, so there are actually no wrong answers to these questions if you actually follow through with the directions. For future reference, we will not do your HW for you here per policy, but you can at least try to disguise your assignments with a little more guile in the future. --Shaggorama (talk) 05:12, 5 September 2008 (UTC)

Actually, Touchtone or Telephone keypad should be consulted as well as harmonics. But in essence: tuning fork: one pitch, sine-wave with few overtones (i.e. simple waveform); human voice: one pitch, complex overtones; Touch-tone phone keypad: two pitches, each with a simple waveform. - Nunh-huh 06:06, 5 September 2008 (UTC)

My god. You took the time to type out verbatim your assignment. And now you are waiting with baited breath for answers from the internet. If you had just done the assignment as it tells you to you'd be done by now. You get an epic fail. --98.217.8.46 (talk) 13:02, 5 September 2008 (UTC)

"Baited breath" - what are you trying to catch? ;) Franamax (talk) 07:09, 6 September 2008 (UTC)

At least link to the explanation of the correct spelling. :P — BRIAN0918 • 2008-09-06 18:02Z

If you really don't trust your ears then record the sounds into your computer and analyze the waveforms with Praat. It should be easy to tell which are more complex, but then again it should be easy enough by ear anyway. - Lambajan 02:51, 8 September 2008 (UTC)

fatigue

comparison of stress at fillet radius and bending stress at uniform sections —Preceding unsigned comment added by 196.21.39.11 (talk) 08:09, 5 September 2008 (UTC)

There are people here. People need to be talked to in complete sentences. Can you please make some effort in that direction? You don't want to waste this resource by sending them on the wrong path, do you?. --Ayacop (talk) 08:51, 5 September 2008 (UTC)

Our articles on fatigue (engineering), fillet (mechanics) and stress concentration might help you, but, as Ayacop says, you need to ask a clearer and more specific question if you want more pertinent help. Gandalf61 (talk) 09:36, 5 September 2008 (UTC)

Not to pile on you here, but seriously, asking "questions" like this is pretty much ridiculous. No one can even properly figure out what you're talking about, much less what you want to know. And, unfortunately, a lot of people do this. Just asking an actual question would be a big help, and providing just a tiny bit of context would go a long way -- and by that I mean that you're going to get a lot more and better answers when people don't feel like pounding a nail into their forehead when they see yet another more or less incomprehensible post. -- Captain Disdain (talk) 11:01, 5 September 2008 (UTC)

If you mean making stress calculations for weldments using a technique similar to the standard method for uniform sections, take a look at this page. Note thought that these are calculations for stress, not fatigue. Fatigue is the result of repeated applications of stress, so you don't get an answer measured in "lbs per sq.in." or anything like that. Franamax (talk) 07:05, 6 September 2008 (UTC)

matchwood

What timber are matches most commonly made from? —Preceding unsigned comment added by 143.238.144.179 (talk) 10:51, 5 September 2008 (UTC)

Mainly aspen and white pine. Axl (talk) 12:02, 5 September 2008 (UTC)

Remember it only takes 1 tree to make a thousand matches, but it only takes one match to burn a thousand trees... 194.221.133.226 (talk) 12:43, 5 September 2008 (UTC)

For those who are confused by the response... 81.174.226.229 (talk) 13:01, 5 September 2008 (UTC)

If someone is getting only one thousand matches out of a tree, either they are cutting baby trees or they have an incredibly wasteful cutting process. Wanderer57 (talk) 17:34, 5 September 2008 (UTC)

I'd say around 5000. JessicaThunderbolt 19:05, 5 September 2008 (UTC)

There is a long tradition in both western and other cultures of using the names of specific large numbers (like "a thousand") to metaphorically refer to an indeterminately large amount. (e.g. when the Nazis referred to "the Thousand Year Reich", they weren't intending to give back Poland come September 1, 2939.) I'd link to an article, but we don't seem to have "Metaphorical use of large numbers", and the articles "large numbers" and "thousand" don't show anything promising. -- 128.104.112.147 (talk) 19:15, 5 September 2008 (UTC)

If I've heard that once, I've heard it a thousand times. --- OtherDave (talk) 02:23, 6 September 2008 (UTC)

You know, a picture is worth a thousand words... Medical geneticist (talk) 21:52, 10 September 2008 (UTC)

Origin of life

What are the probabilites that universal common descent isn't actually true, and that life on Earth is in fact polyphyletic? Couldn't it be that life arose a few times on this planet, and that the basic similarities between living beings are just convergent adaptations to the same selective pressures? Leptictidium (mt) 12:06, 5 September 2008 (UTC)

Pretty unlikely, if you look at DNA and RNA codes there is ample opportunity for variations, but only small variations occur. And the basic biochemistry seems to be the same for all organisms, there is no detected radically different pathways around suggesting a different source of genomes. If you take a look at the book of Genesis in the bible you can see there were three special acts of creation, with the universe, sea creatures, and humans being the three things created and not made. But in any case you can be pretty sure that human DNA has come from animals. Graeme Bartlett (talk) 12:32, 5 September 2008 (UTC)

You might want to look at abiogenesis you question is discussed ever so briefly here. There are arguments that life is may still originating around volcanic vents at least from the theory I prefer Iron-sulfur world theory(metabolism first). How far this new life gets before more advanced life gets a hold of this proto-life-matter isn't very far. So it is very likely that life started in multiple places, and still is, it just can't out do the life that is already established. This is supported, since, we generally don't see life with proteins and DNA of different Chirality (chemistry) we see homochirality. It is likely that origin sources with different chirality were quickly out competed by sources with a common chirality that could combine traits into a single more advanced system (likely a pre-genetics world). The choice of chirality seems random and there is the possibility that there is a planet of life in the universe that is our molecular mirror, take a look here. A very neat subject that is only studied in a limited way. I hope that helps.--OMCV (talk) 12:33, 5 September 2008 (UTC)

Chances are genetic material was not the first biological matter. See abiogenesis for metabolism first vs genetics first (RNA_world_hypothesis). Amino acids and the resulting proteins are far simpler than nucleic acids acids and their polymers. This makes it more likely that amino acids would form and self replicate before the formation of the more complex coding system for self replicating. An analogy would be: there is machinery that works without software but there it no software that works without machinery. Back to biology, glycine is only C₂H₅NO₂ while adenosine is composed of adenine and a sugar molecule for a grand total of C₁₀H₁₃N₅O₄ before adding phosphates. Sure all the other amino acids are more complex than glycine but its variation at one position. In contrast all nucleosides are made of nucleobase, sugar, and up to three phosphates. This means you need to locate these three pieces before you can make DNA. An inorganic metal center with amino acids as ligands which used available substrate to make more amino acids, a proto-self-propagating-enzyme, was probably the first form of life. As far as the bible is concerned, it is generally not a good source of scientific knowledge even if it has significant spiritual and allegorical knowledge as Augustine of Hippo pointed out very early on.--OMCV (talk) 13:43, 5 September 2008 (UTC)

Yeah, but who would trust a hippo? I wouldn't. --98.217.8.46 (talk) 14:43, 5 September 2008 (UTC)

Your comment is blatantly hippocritical. -- BenRG (talk) 15:04, 5 September 2008 (UTC)

One thing the above comments don't address is that "life" in a basic form might have emerged multiple times on the early Earth only to have the gene pools merge together. Lateral gene transfer, i.e. the transmission of genes between non-descendent organisms, is well-documented at various times in history and among various kinds of bacteria. Many of the hypotheses about what the first life may have consisted of point to organisms with far less stable genetic material and less structured cell membranes, which increases the probablity that if cell-like life arose more than once then the different strains could have exchanged genes. Do enough of that and even independently originating life forms could come to share a common genetic heritage. Dragons flight (talk) 19:31, 5 September 2008 (UTC)

The issue with lateral gene transfer is that in order for organisms to share genetic material they have to have the same type of genetic material. To be the same it means the genetic material has to have the same chirality (chemistry) (in multiple locations) and the same coding system for proteins. Its becomes statistically questionable whether life got all the way to genetics material twice because once would be enough. Once life gets to genetics it becomes a collaborative effort with gene trading galore probably even some amount of advancing or cleaning up of the genetic code. Surely whatever came up with genetics blew everything else out of the water. What I mean by blew them out of the water is that they ate the matter that might have been proto-life (and still do). This all ads up to an explosion of life. All "important" life is likely descended from the system that figured out genetics everything without genetics would be left in their biological dust. If earth was void of life (in theory) it might take a very short amount of time for life to develop here. But the reality is that there is so much life here any new comer "proto-life" gets chewed up by those of us with a foothold. Thanks for the comment, Dragon, I just wanted to expand on it.--OMCV (talk) 20:02, 5 September 2008 (UTC)

You assume they have to be the same, when in fact they merely have to coexist well together. Maybe organisms from your iron-sulfur world met other organisms from an RNA world.  ;-) If one had superior genetic structures and the other had superior metabolic pathways they could complement each other even if initially they had entirely seperate approaches to life. Perhaps it was only later that the connection between genetic material and proteins was made. Its more radical than traditional lateral gene transfer (since in particular we are talking about an era before traditional genes), but it is possible, at least in principle, to imagine that some of the features we see as belonging to all cells today orginiated in independent strains of life. Dragons flight (talk) 20:19, 5 September 2008 (UTC)

I get what your saying; critter (a) developes genetics even though it might not have the best proteins at the time. Critter (b) has better proteins or at least a few the first critter doesn't. As long as they don't kill each other it likely that critter (a) and (b) will exchange chemical systems. I'm no biochemist I don't know if the enzyme or system exists now, but surely there has been a mechanism to produce genetic material from proteins. Its just the microscopic reverse of todays standard direction of making proteins from DNA. If critter (a) had this mechanism it could run around finding all the valuable proteins and record their sequence for posterity. Very good point and neat stuff.--OMCV (talk) 21:18, 5 September 2008 (UTC)

Inducing hyperthyroidism to lose weight?

Are there examples of people trying to ramp up thyroid hormone production (or taking thyroid hormone pills) in order to increase the basal metabolic rate to lose weight? How successful is this approach, or does it likewise increase hunger and cause you to eat more? (not for school) — BRIAN0918 • 2008-09-05 15:25Z

Yes, there are examples. Indeed it's a classic MRCP question. It does cause weight loss. However there are several harmful effects of excessive thyroid hormone levels. After ceasing levothyroxine, the person regains weight. Many of these people have co-existent psychiatric illness that may complicate the clinical picture. Axl (talk) 16:54, 5 September 2008 (UTC)

Interesting. So in order to maintain the weight loss, you would have to continue taking the pills, or exercise more (since apparently eating less simply reduces BMR). When you mention psychiatric illness, are you implying that the excess levels caused mental problems, or simply that the example you cited involved people with mental problems, reducing the certainty of the amount of weight loss caused by thyroxine? — BRIAN0918 • 2008-09-05 16:58Z

According to de:Thyroxin (but without refs), other problems are that increase of metabolic rate can be completely revoked by simply eating more, so you'll be probably hungry (and if that is okay with you then why not simply eat less beforehand?). Also, insulin resistance is increased, the heart and circulatory system is stressed, and for women during menopause osteoporosis risk increases. Finally, hormone and TSH values should be checked constantly if you want to do it right. --Ayacop (talk) 17:11, 5 September 2008 (UTC)

Regarding psychiatric illness, the people who abuse levothyroxine in this way usually have an eating disorder (anorexia nervosa or bulimia nervosa) before commencing levothyroxine. Axl (talk) 17:19, 5 September 2008 (UTC)

And hair loss. Let's not forget about hair loss.  :) OK maybe just with a thyroid storm. OrangeMarlin ^{Talk• Contributions} 23:34, 5 September 2008 (UTC)

It's been used...and it's not a good option. TH regulates many different processes in the body and there can be severe cardiac and bone issues, for example, in those out-of-balance. Here's a case of periodic paralysis from abusing thyroxine. — Scientizzle 23:51, 5 September 2008 (UTC)

Yes, there are many examples as cited above. Thyroid supplementation certainly can produce weight loss, but as mentioned above it's not sustainable upon discontinuation of levothyroxine. The reason this is not tried on a wide scale is the cardiotoxicity associated with thyroid hormones. Thyroid hormones sensitize the sympathetic nervous system, producing tachycardia and elevated systolic blood pressure that taxes the heart and can lead to cardiac arrhythmias and heart failure. Not the best approach for weight loss. --David Iberri (talk) 21:25, 8 September 2008 (UTC)

Heres the deal with using thyroid hormones.... Yes they do work, and using T3 (cytomel) is much better then T4 (synthroid) because T3 is the active hormone, T4 is just converted to T3. A few major problems exist: 1. Your body decreases or stops making thyroid hormones when you supplement them, when you get off, its slow to raise its levels back up and during this time period is when most people regain the weight. 2. It doesn't burn fat exclusively, it also burns muscle. You want to preserve muscle because muscle burns calories, you will be burning less calories if you lose muscle, this is part of the reason most people cannot keep the weight off from dieting (also because they go back to their old diet and stop exercising). 3. Its bad for your heart, your thyroid levels being high are bad for your heart and im sure a lot of other things. You will be very uncomfortable and sweat a lot if your thyroid levels are very high.

Many bodybuilders use it and you can find tons of information about it on the steroid forums online. Bodybuilders use it with steroids usually to preserve muscle. There was some talk about how cytomel or HCG could be used to restore thyroid function in a week, but I'm not too sure of it.

americium in smoke detectors

so, how much americium is exactly in an average smoke detector? I know the article says 'less than a milligram' but that's trivially true with a cost of ~$160/mg. --Ayacop (talk) 15:27, 5 September 2008 (UTC)

This says 0.2mg of Americium Dioxide. Fribbler (talk) 15:34, 5 September 2008 (UTC)

Ah, thanks. That's still ~$30/detector but you can get them for much less. So either the file or the price is wrong. --Ayacop (talk) 15:36, 5 September 2008 (UTC)

Google thinks that about $1500 will buy you a gram of americium-241 dioxide. Algebraist 15:51, 5 September 2008 (UTC)

So we're down to 30 cents per detector. — BRIAN0918 • 2008-09-05 16:00Z

If you took the price from [16], note that the $160/mg price is for the isotope Americium-243, whereas ionisation smoke detectors contain Americium-241. Gandalf61 (talk) 15:52, 5 September 2008 (UTC)

Lower cost if you buy in bulk? — BRIAN0918 • 2008-09-05 15:58Z

Certainly too. All my questions have been answered. Thanks again. --Ayacop (talk) 16:50, 5 September 2008 (UTC)

The article says that Americium-241 is fissile with a critical mass of 60 kg (bare, unreflected sphere). Does that mean that with a mere 300,000,000 smoke detectors you'd have enough of the stuff for a nuke? Someone alert the media—this could be the next big thing to get worried about! ;-) --98.217.8.46 (talk) 19:34, 5 September 2008 (UTC)

Radioactive boy scout. Dragons flight (talk) 19:42, 5 September 2008 (UTC)

Right, but even he never tried to make a pure-Americium weapon... --98.217.8.46 (talk) 20:43, 5 September 2008 (UTC)

Monkey wedding

What is the reason of this wedding? Does this serve any purpose? Otolemur crassicaudatus (talk) 15:46, 5 September 2008 (UTC)

It serves about the same amount of purpose as spamming a bunch of nude images on FPC, or linking to this story on RD/S, I reckon. — BRIAN0918 • 2008-09-05 16:17Z

The caption answers your question: "The widlife park organized the wedding in the hope of attracting more visitors, local media reported." Thats about it. Fribbler (talk) 15:51, 5 September 2008 (UTC)

Withdraw post. I should have asked this in Wikipedia:Reference desk/Miscellaneous or Wikipedia:Reference desk/Entertainment, My mistake I asked it in science ref desk. Otolemur crassicaudatus (talk) 16:43, 5 September 2008 (UTC)

Hmm, so you think you'll get a 'better' answer there? 86.4.187.55 (talk) 19:21, 5 September 2008 (UTC)

Yoghurt phobia

I have a phobia if yoghurt, I cant touch it, have it 2 close to me or anything or I will just freak out or breakdown crying. REcently to try an overcome my fear I tryed touching an unopened 'Activia' yoghurt and I almost had a panic attack, also I got a pot of 'Ben and Jerrys chocolate brownie' frozen yoghurt and put my spoon in, poured all the frozen yoghurt off and put my tongue on the spoon, the day I did that I felt completely sick and couldnt eat anything, and was depressed, for the rest of the day. I am slowly dealing with it, those two occasions were big steps, but I was just wondering if there was a name for this phobia or it was common or regognised? 82.16.111.72 (talk) 20:34, 5 September 2008 (UTC)

You really ought to seek professional advice. Other than that, no, it's not got a fancy Latin name and it is not common or recognized as a specific phobia. If it did have a specific name it would probably be Iogurtophobia or something like that (judging from the Latin Wikipedia page for Yoghurt).--98.217.8.46 (talk) 20:41, 5 September 2008 (UTC)

Call it a hunch: but I suspect your condition might have a lot to do with being a bored thirteen year old without much time on his hands who is looking for lulz. Magog the Ogre (talk) 21:27, 5 September 2008 (UTC)

We have a list of phobias, but "fear of yoghurt" is not on that list. On the other hand, it is very common for people to have an aversion to a particular food or ingredient to the extent that they cannot even bear the smell or the sight of it. Gandalf61 (talk) 08:55, 6 September 2008 (UTC)

As noted in List of phobias: "In many cases people have coined these words as neologisms, and only a few of them occur in the medical literature. In many cases, the naming of phobias has become a word game,"...and also..."Note that no things, substances, or even concepts exist which someone, somewhere may not fear, sometimes irrationally so". So even if you found a word for "irrational fear of yoghurt", it's likely that the word would be a totally irrelevent neologism that no practicing doctor would know or use. If one had to tie this down, it would either be a highly specific form of Cibophobia (fear of food) or, perhaps more likely Bacillophobia, (fear of bacteria) - which is the likely reason this person fears strawberry yoghurt but not (say) strawberry mousse - because, despite their near-identical ingredients and near-identical packaging, yoghurt is the result of a bacterial fermentation. If this is the case, why is our OP not afraid of products like beer and bread - which are made in similar ways? SteveBaker (talk) 18:36, 6 September 2008 (UTC)

Becuase it's an irrational fear, why what'd you think? – b_jonas 21:20, 6 September 2008 (UTC)

How is yoghurt different from beer and bread? Only yoghurt contains living microorganisms. - Nunh-huh 01:09, 7 September 2008 (UTC)

Not all yoghurt. The fancy "Activia" stuff does - but a typical flavored yoghurt with bits of fruit in it doesn't. SteveBaker (talk) 18:59, 7 September 2008 (UTC)

Depends on the brand - there are lots of yoghurts with active cultures, not just Activia. This includes those with bits of fruit, and some frozen yoghurts. Yoghurts without active cultures have been heat treated to kill the organisms used to make it, in order to prolong their shelf-life. The only way to be certain if you're getting living or dead organisms in your yoghurt is to read the label. - Nunh-huh 18:37, 9 September 2008 (UTC)

Cyst or what?

I had what my dermatologist called a cyst under my skin, and I just popped it out. It's a small black capsule and I was just wondering what it is exactly. Coolotter88 (talk) 21:12, 5 September 2008 (UTC)

Have you read Cyst? --Tango (talk) 22:03, 5 September 2008 (UTC)

Yes, I didn't find any help there :( Coolotter88 (talk) 22:18, 5 September 2008 (UTC)

I'm not going to do it myself, but it's very, very likely that this question is going to be removed. The only person who can tell you what it is is someone who can look at it with their own two eyes and give you a professional answer.--El aprendelenguas (talk) 22:58, 5 September 2008 (UTC)

It sounds like the OP has already treated the condition themselves, so this isn't really a request for medical advice. Idle curiosity about medical matters is an appropriate topic for this desk. --Tango (talk) 23:26, 5 September 2008 (UTC)

That is correct, I'm not asking for medical advice, I'm just curious what this thing is that came out of my body. It is a capsule about 1-2 millimeters long. It is fairly hard as I can't crack it with my nail (okay, we're not comparing gemstones here, so yeah). Coolotter88 (talk) 23:31, 5 September 2008 (UTC)

What Tango is saying is that we don't do medical diagnostics here. We leave that to House (TV series) and ER (TV series), both fine TV shows. Really, bring it to your physician. OrangeMarlin ^{Talk• Contributions} 23:33, 5 September 2008 (UTC)

Another way to put it so the OP may possibly understand... Claiming "It's a small black capsule" does not narrow it down to one or two things. It narrows it down to a few thousand (if not more) things. Do you honestly believe that getting a list of a few thousand things that appear to be hard black capsules will provide you any help in any way? Of course not. Take it to a doctor and get a real answer. -- kainaw™ 23:54, 5 September 2008 (UTC)

Have you been hanging out in the jungles of South America recently? -- 71.125.61.216 (talk) 02:38, 6 September 2008 (UTC)

Did it look like these little capsules[17] sometimes found under the skin? Edison (talk) 03:55, 6 September 2008 (UTC)

Some more information like what age are you and where was the cyst would be helpful. However I am going to suggest the most likely possibility. It is a dried up sebaceous cyst (aka comedo) that has encapsulated and separated itself from the surrounding tissue. It is hard because all the oily cheesy secretion and skin flakes have concreted together. I'd be interested to hear what the 'few thousand' other possibilities might be. Richard Avery (talk) 10:28, 6 September 2008 (UTC)

Thank you, that's probably what it is, I was just looking at sebaceous cyst and I had asked my mom what it was (she used to be a doctor). She said the most likely thing was that it was a dried up cyst. That's a good enough answer for me. Coolotter88 (talk) 11:20, 6 September 2008 (UTC)

Need a 3D anatomy applet

Dear Wikipedians:

I'm taking a gross anatomy course right now and am in desperate need of a 3D human anatomy applet that could be run from the browser. Any pointers?

Barring that, are there any good 3D human anatomy software out there?

Thanks,

76.65.15.205 (talk) 22:34, 5 September 2008 (UTC)

Would something like the Visible Human Project do? At the bottom of the article are several links to online viewers. SteveBaker (talk) 02:10, 6 September 2008 (UTC)

wow! That's soooo good! thanks a lot steve! 74.12.198.186 (talk) 15:18, 7 September 2008 (UTC)

You don't want to know how they got their data though...it's kinda gross! SteveBaker (talk) 18:55, 7 September 2008 (UTC)

September 6

Potassium Carbonate as a Fire Supression Agent

The Scientific American website currently has a news story [18] about a fire suppression "grenade" which uses potassium carbonate as its active ingredient to suppress fire "at the molecular level". It appears that potassium carbonate/potassium bicarbonate is a common ingredient in fire extinguishers (e.g Purple-K). However, none of those pages mention how it works, except for Purple-K saying it "directly inhibit[s] the chemical chain reaction", with the CO₂ smothering being relegated to a minor role (as expected, since potassium chloride also works in fire suppression). - So what is the mechanism for potassium (bi)carbonate fire suppression? -- 128.104.112.147 (talk) 00:19, 6 September 2008 (UTC)

This old patent seems to indicate that part of it is that heating potassium bicarbonate will release both CO₂ and H₂O. Perhaps that has something to do with it? (I'm no chemist) --98.217.8.46 (talk) 00:45, 6 September 2008 (UTC)

See HowStuffWorks --Russoc4 (talk) 02:36, 6 September 2008 (UTC)

I'm pretty sure I sure something on one of Adam Hart-Davies's shows, where he demonstrated glass fire extinguishers (probably Victorian era). They were roughly grenade shaped and sized, and contained bicarbonate of something. DuncanHill (talk) 09:48, 6 September 2008 (UTC)

Those links don't exactly answer my question. The article potassium chloride (KCl), notes that it works as a fire extinguishing agent, but obviously doesn't have any CO₂ or H₂O to release. HowStuffWorks is claiming that dry chemical fire extinguishers work by smothering the fire by coating the fuel with an "inert solid (similar to dirt or sand)". However, the article Purple-K notes that "Dry Chemical Powder works by directly inhibiting the chemical chain reaction" (the bottom of the fire tetrahedron, versus the oxygen leg of the fire triangle, as implied by HowStuffWorks). The article potassium carbonate notes that aqueous potassium carbonate is used for restaurant fires - so it's not just water release (as they'd use just water), and it isn't smothering with an inert solid (as the dissolved carbonate isn't a solid). - So to clarify my question, I'm looking for confirmation if there is some sort of chemical (versus physical) mechanism of action in potassium/sodium bicarbonate/carbonate/chloride fire suppression, and if so, what the chemical mechanism is. -- 128.104.112.147 (talk) 19:38, 6 September 2008 (UTC)

Consider two Cockatiels, A and B...

Both birds are the same sex and age. Both are descended from many tens of generations of captive-bred stock. Both have been parent raised and kept in an aviary with others of their own kind for their whole lives. A lives in England. B lives in China.

Now suppose that A and B were to be introduced to each other in aviary conditions. Would they be able to communicate and interact with each other in the same way as two wild Cockatiels of the same age and sex from roughly the same area in their natural habitat would - or would there be a significant 'language gap'? --Kurt Shaped Box (talk) 01:23, 6 September 2008 (UTC)

Good question, and I can only imagine they could at least communicate basically. After years of separation in the New World, Americans simply developed a different language from their English ancestors, they don't speak a strange unrelated language called American. Further, any normal bird doesn't answer direct commands like a dog - "sit, fly" etc. Unless, like a parrot, it learns to talk, it's Chinese speaking owners are hardly going to morph it into a different "bird language." Unfortunately it would take a long time to find out, though.78.144.137.205 (talk) 08:51, 6 September 2008 (UTC)

If they wanted to sit around and discuss the current political situation then clearly they would need a common language. But what sort of communication are we talking about. I have never kept these birds but most of their communication is about posture, eye contact, squawking, pecking and scratching. Wouldn't all of that stuff be genetically hard-wired? If you went to a country where you spoke not a syllable of the language I'll bet you could communicate quite a lot without speaking - facial expressions for starters. A smile is a smile and a frown is a frown wherever you go in the world. When you start using language that moves the personal interface (can I say that?) to a higher plane, one not necessarily available to even sibling cockatiels. Richard Avery (talk) 10:17, 6 September 2008 (UTC)

There are really four possibilities here:

1. That parrots learn "language" (or body language or whatever) from their parents. In which case, in your thought experiment, it's likely that the chinese birds would have gradually drifted from the original language - but would that be enough so they couldn't communicate? Who knows? However, you could test this hypothesis with a bird raised entirely by humans who could not have learned from a parent bird and in just one generation would have entirely lost the ability to communicate with others of its species.
2. That parrots have language built in at the genetic level as an "instinct" - and therefore all parrots, no matter how they are raised can communicate.
3. That language is genetic - but that the evolutionary/genetic "drift" would be so rapid that our chinese birds would be unable to understand their English counterparts. This seems unlikely.
4. That parrots don't really communicate with each other much at all making the question entirely moot.

It seems to me that (1) and (4) should be easy to test. If you can eliminate those two then we're down to a genetic/inherited effect - and then if the chinese birds can communicate then it's (2) and if they can't, it's (3).

I presume that such studies have been done for bird-song in general - but perhaps parrots (with their talent of mimicry) are special. That inherent ability to mimic suggests to me that they pick up language from other parrots nearby - so (1) is most likely to be the case and therefore the 'linguistic drift' with the chinese birds may make communication difficult - but perhaps not impossible. But that's entirely supposition based on the idea that mimicry in parrots is there solely to enable them to learn "parrot talk" from their parents and not for some other reason. SteveBaker (talk) 12:25, 6 September 2008 (UTC)

According to Animal_communication#Animal_communication_and_linguistics, Human language is largely learned culturally, while animal communication systems are known largely by instinct, which would suggest both cockatiels would be able to communicate by the same techniques and efficiency as two who were raised in the wild.--El aprendelenguas (talk) 18:26, 6 September 2008 (UTC)

Thanks for the answers so far, folks. As to Steve's comment - I *think* that the main reasons that parrots 'parrot' is to enable the individuals from a certain flock to communicate with each other more easily over distance, or when aggregating with other flocks. IIRC, each bird copies certain unique elements of the vocalizations from the other birds in the local flock (which consists of relatives and trusted associates - friends, basically) to weave a 'song' (yeah, I know - parrots don't really have what we would call a 'song') that is unique to that flock and is recognized by all other members of the flock as belonging to a bird from that flock. Male birds will also attempt to accurately mimic the calls of females when wooing them, also embellishing the 'song' with sonic elements taken from the surrounding environment - which is apparently seen as a desirable trait in a potential mate (and explains why male companion parrots tend to be be better talkers). Sorry, no refs - this is all 'I read it on the web somewhere' stuff... --Kurt Shaped Box (talk) 15:02, 8 September 2008 (UTC)

Winter Solstice

Does this help? SteveBaker (talk) 02:05, 6 September 2008 (UTC)

Did the Winter Solstice fall on the 22nd in 1990?

Or how can I track down that info? It's hard to find old calendars... 128.239.177.28 (talk) 01:29, 6 September 2008 (UTC)Capricorn

How about this? -hydnjo talk 02:22, 6 September 2008 (UTC)

Yes, the solstice was at 03:07 UT on 22 December 1990.--Shantavira|^{feed me} 08:20, 6 September 2008 (UTC)

The answer depends on where in the world you live. The solstice occurred at the same absolute instant everywhere inthe world. This was 1990-12-22-0307h UTC, but this was 1990-12-21-2207 EST.-Arch dude (talk) 11:31, 6 September 2008 (UTC)

And if you happened to be in the southern hemisphere, then the winter solstice was at about 15:38 TDT on the 21st of June. Algebraist 13:27, 6 September 2008 (UTC)

Verily. Inhabitants of the northern hemisphere sometimes think their half is the only half worth worrying about, and is therefore for all intents and purposes the entire world. But we southerners know differently.  :) -- JackofOz (talk) 14:41, 7 September 2008 (UTC)

Awwww. I thought it would be cool to have been born on the solstice, but I was born in Massachusetts, where it seems the solstice occurred on the 21st. So I was born on a plain old non-holiday. I don't suppose anything interesting ever happened on the 22nd of December?

And I apologize if I unintentionally insulted anyone south of the equator. I think Australian and New Zealand accents are some of the coolest in the world, if that helps. 128.239.177.28 (talk) 17:03, 7 September 2008 (UTC)Capricorn

You should read December 22 - that article has a long list of things that happened on that day. In fact, the very day you were born (Dec 22 1990) was "Final independence of the Marshall Islands and Federated States of Micronesia after termination of trusteeship. and you share a birthday with the "famous" French actor Jean-Baptiste Maunier - and you thought nothing interesting happened!...(OK, maybe you have a point!) Hmmm...Disneyland opened on the day I was born! SteveBaker (talk) 18:52, 7 September 2008 (UTC)

I'm not too sure what "final independence" means (they were free for the last time? so they were taken over immediately after that?)and I'd never heard of the Federated States of Micronesia, though according to its article it's a real place somewhere in Oceania. But thanks anyway! I guess I'll have to start watching more French movies to see Jean-Baptiste Maunier... 128.239.177.28 (talk) 13:53, 8 September 2008 (UTC)Capricorn

Drugs that daze or slow down?

1. What category of drug generally slows down your movement or walking speed?
2. What category of drug drug puts you in a daze, e.g. making you only able to do one thing in the time it would take you to do 2 or 3?

(Or names of specific drugs with these effects)--Sonjaaa (talk) 02:18, 6 September 2008 (UTC)

Depressants. --Tango (talk) 02:22, 6 September 2008 (UTC)

Alcohol (EtOH) being the most prevalent. -- MacAddct  1984 ^{(talk • contribs)} 02:33, 6 September 2008 (UTC)

Thorazine is somewhat legendary in it's ability to put people into a slow-moving, slow-witted daze. --Kurt Shaped Box (talk) 02:47, 6 September 2008 (UTC)

1. Drug-induced parkinsonism, notably antipsychotics (of which Thorazine (chlorpromazine) is one). Axl ¤ [Talk] 10:00, 6 September 2008 (UTC)

Maximum Water Vapor In Air

Why is there a specific maximum amount of water vapor that can exist in air at specific temperatures? A similar question would be 'Why is there a dew point temperature for each air temperature?'. I have searched the internet (and Wikipedia of course) and have not been able to pick up this answer. 172.168.186.87 (talk) 03:04, 6 September 2008 (UTC)

Have you read dew point? It doesn't have a very detailed explanation, but it has a brief one. If you want more than that, you'll have to wait for someone more knowledgeable to come along, I'm afraid. --Tango (talk) 03:12, 6 September 2008 (UTC)

As this is a phase transition you have a critical point in the system. --Ayacop (talk) 07:06, 6 September 2008 (UTC)

While that is correct, of course, it's hardly helpful to the OP, I would think. Basically, two forces are at work here: entropy favours all the water molecules to be homogeneously distributed in the form of vapour, while the attractive Van der Waals forces between water molecules favour the water molecules to be close (i.e., favours the liquid form of water). Now, if the certain amount of water in the air exceeds a certain limit (or the temperature drops below the dewpoint), the attractive forces become strong enough to overcome the entropic forces and it becomes energetically favourable for the system to separate into two phases (drops of liquid and the existing vapour). In the liquid fase, the energy of the attractions is low, while in the gaseous state, the entropic contribution to the energy is low, and the fraction of water that condensates will be such that the total energy of the liquids droplets and the vapour together will be lower than the energy of a system where only vapour would be present. --baszoetekouw (talk) 09:40, 6 September 2008 (UTC)

Can you add that to the article? Titoxd^{(?!? - cool stuff)} 02:02, 7 September 2008 (UTC)

Here is a really excellent overview of the process, specifically worded to avoid the rather poor metaphors often employed by textbooks. Further on the website here you can find the replies to the protests you'll make after reading the first page. Matt Deres (talk) 01:56, 7 September 2008 (UTC)

Mystery critter

Mystery buglie

Two questions: 1) What is it, and 2) Why do I keep finding them in supposedly-sealed packages of food? --Carnildo (talk) 07:02, 6 September 2008 (UTC)

I don't have an answer for what it is, but I think you should be writing to your local trading standards officer as well as the Wikipedia Refdesk. SpinningSpark 08:07, 6 September 2008 (UTC)

Where do you live and what is the country of origin of the food?--Shantavira|^{feed me} 08:22, 6 September 2008 (UTC)

Is it hairy? Anthrenus verbasci - larva side (aka).jpg on the German wikipedia [[19]] looks similar! In english it might be a Dermestidae larve.--Stone (talk) 09:13, 6 September 2008 (UTC)

No, not hairy. --Carnildo (talk) 09:16, 6 September 2008 (UTC)

Western US, the food is mostly dry goods (flour, noodles, rice, etc.) from the local supermarkets. I'm not sure if they're inside the packages to start from, or if they've taken up residence in my pantry and are eating their way into the packages. I only rarely spot them outside the packaging, and they're invariably dead when I do find them. --Carnildo (talk) 09:16, 6 September 2008 (UTC)

It looks a bit like a Mealworm beetle larva. --baszoetekouw (talk) 09:43, 6 September 2008 (UTC)

It could be a waxworm the larva of one of the family of Pyralidae moths. Try image googling 'waxworm'. Richard Avery (talk) 10:04, 6 September 2008 (UTC)

I think Richard Avery is right. HERE is a link to one common species of Pyralidae. It can get into small spaces and loves grain products. Do you often see small moths flying around in your kitchen?

If these are what you have, the texture of the infested flour (or other finely ground grain) is likely to be unusual, as if it was impregnated with many tiny spider webs. It could be described as "stringy".

If this is what you have, the nontoxic traps mentioned in the article are worth trying. They are made specifically for this pest and can catch hundreds of moths. If you google "pantry moth trap pheromone" you can find more information. My local hardware store sells the traps. Maybe yours does also. Wanderer57 (talk) 17:10, 6 September 2008 (UTC)

I'd say they're mealworms (I've also seen some bugs that look like the adult beetles in that article), but the larva and adults I've seen are less than half the size mentioned in the article. --Carnildo (talk) 19:17, 6 September 2008 (UTC)

If I can make a recommendation... we've always found that sealing flour and sugar in large glass containers to be the most effective way of deterring pests of this sort. Boxes and bags just don't cut it. --98.217.8.46 (talk) 18:35, 6 September 2008 (UTC)

UK Coal Reserves

The table, entitled 'Proved recoverable coal reserves at end-2006 (million tonnes (teragrams))' in the Coal article, under section 'Production Trends', subsection 'World coal reserves', does not include an entry for the United Kingdom. This source states that there are enough 'untapped coal reserves in the UK to last 400 years.' and this source states that there 'are around 250 million tonnes of coal not yet mined in South Wales' (obviously this excludes the rest of the UK). My question is: Is the table incomplete, are the two BBC reports incorrect, or is there another explanation? I've asked this question on the Coal article talk page, but haven't received a response. Thanks, Daicaregos (talk) 08:24, 6 September 2008 (UTC)

The source for that table has the UK with only 220 million tonnes, which is less than 0.05% of the world total, so wasn't included in our table. The source says that it only includes reserves that are known to be extractable under "existing economic and operating conditions", so perhaps they didn't include all the coal mines in the UK that have been closed with coal still in them. Seems an odd decision - they can be re-opened pretty easily if the need arises. --Tango (talk) 08:06, 6 September 2008 (UTC)

Thanks for your reply, Tango. That makes sense (why it's not on the table). Perhaps the discrepancy between your source and the BBC/Media Wales sources will disappear when they next update their table. We'll see. In the meantime I'll update the United Kingdom, economy section to read reserves of at least 220 million tonnes (It currently says 'The UK has a small coal reserve'. 220 million tonnes doen't seem that small to me though). Would you mind posting the link to the reference please, so I can quote it? Cheers :) Daicaregos (talk) 08:24, 6 September 2008 (UTC)

As usual - let's crunch the numbers guys: Fossil fuel power plant says that a typical coal-fired power station uses 10,000 tons of coal per day. (1 tonne == 1.1 ton) So 220 million tonnes (240 million tons) is only enough to run one "typical" power plant for 24,000 days - about 70 years...or 70 power plants for one year. I'm fairly sure there are more than 70 coal-fired power stations of "typical" size in the UK. So 220 million tonnes is NOTHING...not even a year's supply for the UK. That's hardly a significant reserve - in fact it's such an utterly trivial amount as to be essentially negligable - and it certainly doesn't come close to explaining the "400 years" figure. (And this assumes that no coal is used in other industrial uses - such as coke production - which is needed for steel making and other industrial activities) SteveBaker (talk) 12:09, 6 September 2008 (UTC)

According to one of the tables at [20], Britain uses about 50 Megatonnes of coal a year in electricity generation. I am still digginf for information on the UK's coal reserves, but it should be noted that they declined sharply after the Conservative government's pit closures of the 80s of last century. This is because reserves are usually quoted of coal which is both technically and economically recoverable. The costs of reopening a deep mine are massive (dewatering, propping, ventilation etc), so while the coal may be there, at current prices it isn't worth getting it out. DuncanHill (talk) 12:24, 6 September 2008 (UTC)

And this paper [21] suggests that there is a minimum of 7 billion tonnes of coal in the UK suitable for underground coal gasification. DuncanHill (talk) 12:28, 6 September 2008 (UTC)

This last paper says 'The volumes represent 200 years based on the current UK coal consumption of 64 mt p.a.'. Is this paper correct/worth quoting? Or do you guys think I should just leave the United Kingdom, economy section to people who actually know what they're talking about? Daicaregos (talk) 18:48, 6 September 2008 (UTC)

I think the paper is worth using, (it is from the UK Coal Authority), but do be careful about which of the estimates you use from it, and how you introduce them, as the assumptions on which they are based are important for an understanding of them. DuncanHill (talk) 18:54, 6 September 2008 (UTC)

Well DuncanHill, would you care to make the amendment to the United Kingdom article, Economy section? You seem to know what you're talking about, and we both know that I don't. I only knew that it wasn't right. How about it? :) Daicaregos (talk) 19:27, 6 September 2008 (UTC)

Well, OK, but not straight away, I'll need to read, mark, learn and inwardly digest the paper first - I'm not an expert in this area, just a chap with a love of holes in the ground which have useful stuff at the bottom of them. DuncanHill (talk) 19:44, 6 September 2008 (UTC)

DuncanHill, you're an absolute star. At least you know it'll be right. Many thanks. Daicaregos (talk) 21:01, 6 September 2008 (UTC)

Body Temperature

I heard of an unusual feature where some people's body temperatures are higher than average, at about 100-102 degrees Fahrenheit. Is this condition real and is there a name for it if so?CalamusFortis 15:14, 6 September 2008 (UTC)

Hyperthermia is one of the dangers of congenital insensitivity to pain with anhidrosis because subjects won't feel that they heat up due to the anhidrosis, similar to people suffering from quadriplegia who have the advantage of normal perception above the shoulder, so they can change to lighter clothing before becoming too hot due to the anhidrosis. --Ayacop (talk) 16:41, 6 September 2008 (UTC)

That's a start, but not quite the answer I wanted. The condition of higher than average body temperature occurs all the time. The person's body temperature is normally about 100-102 degrees Fahrenheit, not because the person absorbs too much heat but because his or her body temperature is naturally regulated at 100-102. Is it a symptom of hyperthyroidism?CalamusFortis 17:56, 6 September 2008 (UTC)

There is significant variation of "normal" body temperature between different people - and technically, half of all people in the world have higher than average body temperature while the other half have lower than average. It varies throughout the day and for women, throughout their menstrual cycle. Our pyrexia article says that normal body temperature varies between individuals by about 1 degree F - so someone who is up at 102 is definitely not considered "normal". This makes me suspect that the condition is not in fact "real". The hypothalamus is responsible for temperature regulation. I don't see a name for this problem though...the names seem to relate to the specific causes of elevated temperature. SteveBaker (talk) 18:21, 6 September 2008 (UTC)

If by "all the time" the OP means that this is a common condition, then I would want to see a WP:RS; if "all the time" in rare individuals is meant, then that is more likely. In addition to the work of Phil Mackowiak, my comment is based on personal experience having looking at daily temp curves in thousands of inpatient adults over the past 20 years. There is a distribution in average temperatures in persons without overt infection, but it's a pretty narrow distribution and many of those with higher temperatures are subsequently found to have occult disease conditions. Scray (talk) 19:38, 6 September 2008 (UTC)

I should have clarified. What I meant by "all the time" is that the small number of people who have the condition have their temperatures elevated permanently because their bodies maintain their temperatures that high.CalamusFortis 23:05, 6 September 2008 (UTC)

Crystal Filter and Clocks

1. Are the crystals in the crystal filter same as crystals used oscillator circuits?
2. Can some one direct me to good resource which has details on how Tx and Rx synchronize their clocks.(wireless n/w).
3. Suppose I am using two crystals of same frequency from the same manufacturer and using them in Tx and Rx circuits as clocks(After frequency division from several MHz to say 3 or 4kHz)(No temeperature oven or anything fancy...). Once synchronised, how long will they be in sync(order of magnitude) before requiring resynchronization? Lets say that the the Tx and Rx are in the same house or within 20 to 30 metres of each other so that their environment is essentially the same...

59.93.2.176 (talk) 18:20, 6 September 2008 (UTC)

• 3:you may be able to get a one part per million match in the frequency. Then at 4kHz it would take 250 seconds to drift one cycle. Even in the same house you cannot expect to get identical temperatures. With a good oven you may be able to get 1 in a hundred million stability, and if you need higher periods of coherency with out synchronisation you may wish to use a rubidium frequency reference. Graeme Bartlett (talk) 21:50, 6 September 2008 (UTC)

and, still on #3, how long will they be "in sync" and how frequently they "require" resynchronisation is a function of your application requirements. They're really never in perfect sync; you have to decide what degree of unsync is acceptable. You take the maximum drift (from the crystal's datasheet), do the calculation that Graeme describes, and then compare that to how out of sync you're willing to be. But in the real world you'll resynchronise more frequently than that, to account for worst-case problems in your syncrhonisation scheme, and (this being engineering) an embarassingly large fudge-factor to boot (for all the stuff you don't know to take into account). -- Finlay McWalter | Talk 22:06, 6 September 2008 (UTC)

I'm not sure what the application is here - but generally, in any data transmission system, you use the crystal in the receiver to get you CLOSE to the transmitter's frequency, then use a Phase locked loop to lock into the precise frequency of the transmitter. SteveBaker (talk) 21:58, 6 September 2008 (UTC)

To Steve- The application is that I'm trying to make (as a part of a project) a serial digital wireless transmission system without using custom chips; as I will not learn anything new if those chips do all the work. So I'll try to use only basic stuff like counters, freq dividers, PLLs, decoders, MUXs, DEMUXs etc... Its reinventing the wheel, and may be too advanced or complicated for me...

Well, I'm not sure I want to lock to the carrier itself. Say I'm plannig to use ASK i.e. switching on and off the carrier according to the ones and zeroes; So i want to sync with the switching frequency (bit_rate^-1). If the switching time is a factor of the carrier frequency (i.e if a bit takes up integral number of carrier cycles), then I will implement your idea. So synchronization will need to be done only once (neglecting problems).Thanks

59.93.15.56 (talk) 07:27, 7 September 2008 (UTC)

1. One more question: I did some SPICE sims on a (not so well designed) crystal filter. The loss due to that stage was much more than 3dB. In what range do these filter's insertion(?) losses lie generally?

September 7

Why do rockets need to be explosive to reach escape velosity?

Years ago there was a short-lived TV show starring Andy Griffiths ("Salvage 1"). In this show, he was a junk collector of things in Earth orbit and (he hoped) on the moon. One of the unique things about his approach to travelling to outter space was to avoid the current explosive rocket approach and instead used a gradual accelleration approach to achieve orbit. On the surface, this seems to make some sense al a gradually accellerating your car at the intersection rather than doing a "jack rabbit start."

My questions is: what are the physics behind the need for an explosive accelleration to achieve orbit rather than the gradual accelleration premise of this TV show? —Preceding unsigned comment added by 209.161.211.89 (talk) 00:53, 7 September 2008 (UTC)

I remember Salvage 1, so it must have played on the American Forces Network in Germany. I recall the line, "The Vulture has landed". I don't recall the gradual approach to orbit. --—— Gadget850 (Ed) ^talk - 01:15, 7 September 2008 (UTC)

It's more efficient. All the time you're moving upwards, rather than being in a stable orbit, you have to burn fuel just to maintain your position (and more to move up). It's best to get into orbit as quickly as possible to minimise the fuel used up in that way. --Tango (talk) 01:17, 7 September 2008 (UTC)

Check out rocket engine. --—— Gadget850 (Ed) ^talk - 01:19, 7 September 2008 (UTC)

(edit conflict) Yay, finally one that I can answer. Theoretically speaking, it actually doesn't matter how you approach the task of escaping Earth's gravity, as long as you have a Δv large enough to reach escape velocity. However, the problem is that of all the propulsion technologies out there, chemical rocketry is the only one that has a high-enough specific impulse for a reasonable payload/total mass ratio, a high-enough thrust-to-weight ratio to counter Earth's gravity, and is deemed sufficiently safe to use. We could definitely use nuclear propulsion, but it is socially unacceptable to do so. Titoxd^{(?!? - cool stuff)} 01:26, 7 September 2008 (UTC)

However, what that delta-V is depends on how long it takes you. See gravity drag. --Tango (talk) 01:34, 7 September 2008 (UTC)

In simple terms, before you reach orbit, you're using fuel to do two things: 1) Maintain your current position above ground, and 2) increase your speed towards orbital velocity. The quicker you get into orbit, the less fuel you need to use for (1), which is why current rockets accelerate so hard. Once you're in orbit, you can use gentler, more fuel-efficient technologies like solar sails and ion drives to move around. --Carnildo (talk) 01:37, 7 September 2008 (UTC)

Hence the "theoretically speaking"... Titoxd^{(?!? - cool stuff)} 08:55, 7 September 2008 (UTC)

Indeed, the most efficient way (in terms of propellant/payload mass ratio) to launch a spacecraft into orbit would be to fire it from a cannon, putting all the acceleration (except for the final orbital insertion burn) at the very start of the climb. In practice, of course, the stress this would subject the launch vehicle (not to mention any passengers or other payload) to would be prohibitive, so our current rockets are essentially a compromise between fuel efficiency and limits of practical construction. —Ilmari Karonen (talk) 01:51, 7 September 2008 (UTC)

If you were launching from the Moon, where there is no atmosphere, the cannon launch method would work better than on Earth, where if the spacecraft emerged from the muzzle of the gun at orbital velocity near the ground, as in the Jules Verne story [[[From the Earth to the Moon]]] it would decelerate and fall to the ground due to the resistance of the air, if it did not burn up first. It is better to reach high velocity only at an altitude where the air is very thin. I expect that higher G acceleration is more efficient of fuel,except for the burning up in thick atmosphere problem, and the killing the passengers from high G force problem. Rising very slowly would be extremely wasteful of fuel in a rocket. Edison (talk) 04:20, 7 September 2008 (UTC)

On the Moon, you could launch sideways and go straight into orbit (you would need a circularisation burn at some point) rather than going straight up and then going sideways to enter orbit which you need to do on Earth because of the atmosphere. That's the best way to make use of a cannon style launch (see mass driver). --Tango (talk) 04:49, 7 September 2008 (UTC)

See also this thread from a couple of weeks ago. --Anonymous, 05:35 UTC, September 7, 2008.

Of course, you don't need a rocket if you have a space elevator ! Gandalf61 (talk) 08:45, 7 September 2008 (UTC)

Once you are off the planet surface and out of atmosphere engines with slow steady accelaration start to have advantages such as light sails, Bussard ramjet and tether propulsion. SpinningSpark 09:42, 7 September 2008 (UTC)

You don't need to get off the ground with chemical rockets, though. You can use a rocketship/airplane hybrid craft. Using airplane technology while you're still in the atmosphere. The Scaled_Composites_White_Knight carried Spaceship One into the air on conventional jet engines and then dropped it before Spaceship One's rocket engines kicked in. . APL (talk) 16:07, 8 September 2008 (UTC)

Right. Here is a thought experiment: What would happen if we built a spiral-staircase tall enough to reach geostationary orbit? It would be 165,000 miles tall. We could don our space-suits and walk up it (with frequent stops to catch our breath!)...and with the gentlest of push from the topmost step, we'd be in orbit. No "escape velocity" required - no rockets - nothing. SteveBaker (talk) 17:39, 8 September 2008 (UTC)

Well, of course you don't need escape velocity if you only want to go into orbit. When you push off the top step you are, however, at orbital velocity for the given altitude, as the tower is rotating with the Earth. But if you built the tower even higher, you could reach escape velocity in the same way -- that is, the escape velocity for the altitude you were at. The concept is called a space elevator, among other names; see that article for a list of them. --Anonymous, 21:43 UTC, September 9, 2008.

Contents of Drinking Water

What are the contents in the potable/drinking water and what is the ideal percentage of each of the constituents? —Preceding unsigned comment added by 59.97.48.77 (talk) 02:04, 7 September 2008 (UTC)

Did you look at water treatment? Normally there should be water close to 100%. Some dissolved air and carbon dioxide prevents it having a flat flavour. Usually water will be treated with lime to increase it's pH so that it does not dissolve pipes. Other ingredients like chlorine may kill unwanted lifeforms, but really you want zero of this! In the middle east, salt is added because locals prefer their water to taste salty. Ideal percentages of minerals and contaminants may come down to an economical choice - is it worthwhile to remove the contaminants? Graeme Bartlett (talk) 05:53, 7 September 2008 (UTC)

The absolutely pure water taps in the chemistry labs at my uni have warnings saying the water is harmful if consumed frequently. I'm not sure of the details, but presumably there is something about the minerals in water that is important. --Tango (talk) 05:57, 7 September 2008 (UTC)

See Tonicity#Hypotonicity for the general explanation but there might be a specific page with information regarding aqua dest..

/wrt chlorine, you need some means to keep the pipes without microorganisms. That is why you have chlorine in tap water, but I never understood why in the US tap water is chlorinated when you can have clean pipes using ozone. Which is much less toxic and doesn't have any taste. --Ayacop (talk) 10:06, 7 September 2008 (UTC)

Ozone is toxic too. Maybe it's more expensive/less readily available. --Russoc4 (talk) 13:39, 7 September 2008 (UTC)

Water purification#Disinfection notes that "the main disadvantages of ozone is that it leaves no disinfectant residual in the water". I know that my local water system aims to leave a set (ppm) level of chlorine at the customer's tap, to ensure that no harmful organisms sneak in between the supply and the consumer. There really isn't a way to guarantee that one of the decades-old pipe somewhere in the supply system doesn't have a pinhole leak, or some dead pocket where bacteria can establish a colony. I've been in small towns in the US where they were confident enough in their system not to use chlorine, but in a city of any size, there is just too many worries not to have some sort of residual disinfectant capability throughout the supply line. -- 128.104.112.147 (talk) 19:03, 7 September 2008 (UTC)

Hah! Talk about synchronicity. The Sept. 9 question in the New York Times science column q+a is "Is it safe to drink distilled water? Does it leach minerals out of the body?" It's safe, according to "two experts on water quality and nutrition at Cornell". Clarityfiend (talk) 22:32, 9 September 2008 (UTC)

college student seeking advice

Hello, I am a first year student at Mohawk College enrolled in the social service worker course. My main goal for the future is to become a "family therapist". I have experience dealing with people who suffered from alcohol and drug addiction, and I was able to help them gain some will power and get help for themselves. Ever since then, I have had this sudden urge to help anyone and everyone who struggle in life. When I first applied to Mohawk I was under the impression that once I graduated with a degree in social service worker, it would be much easier to apply and be accepted to a university. After doing some research at different universities surrounding our area, I have been unable to find any course that has any relation to "family therapy". If you have not yet figured out where I am going with this, it is that the "social service worker" title is not going to satisfy me. I want more than that...

If you have any advice, or school suggestions, or course suggestions..PLEEEAAAASE respond ASAP

Thank you :)

Trippy123 —Preceding unsigned comment added by Trippy123 (talk • contribs) 03:09, 7 September 2008 (UTC)

Marriage and family therapists#Licensing and Degrees might help. --Tango (talk) 03:41, 7 September 2008 (UTC)

In Ontario Canada, a Social Worker and a Social Services Worker (though governed by the same College) tend to provide two different services based on their education and experiences. Speaking from personal experience, I would suggest that you complete your SSW and then apply to a university for a Social Work program. In my opinion (having supervised students from there, the WLU has one of the best clinical programs around. Also, remember, the university degree is only the starting point: you will need on-going training for several years to come. I completed my BSW (after my BA) and found that until I had my MSW, my oportunities were limited. I also participated in the Introductory and Advanced levels of Brief Therapy in Toronto - this was the BEST clinical training I have ever had and well worth the money!.

So, be patient and plan carefully. I have been at this for 20 years and still have a ways to go!

Brett, MSW, RSW —Preceding unsigned comment added by 69.77.185.91 (talk) 20:54, 8 September 2008 (UTC)

Molar polarisation

how and why is molar polarisation related to molar refractivity? —Preceding unsigned comment added by 59.103.63.240 (talk) 07:29, 7 September 2008 (UTC)

See molar refractivity and compare the Clausius–Mossotti relation with equation (18) for molar polarisation in this. SpinningSpark 10:08, 7 September 2008 (UTC)

Meiosis combinations

Can someone confirm if the number of different gametes possible during meiosis of a human is 2^23? —Preceding unsigned comment added by RMFan1 (talk • contribs) 11:54, 7 September 2008 (UTC)

Even without addressing the specific combinatoric calculation, we can say that's a very low number, because you've ignored the likelihood of recombination, which occurs, on average, slightly more than once per chromosome pair per meiosis. GIven that recombination can occur at so many different locations, the number of different possible gametes is virtually unlimited. - Nunh-huh 12:11, 7 September 2008 (UTC)

why can I listen to the radio on my computer?

Sometimes I can listen on the speakers of my computer to the radio. The sound is quite faint, but it is clearly a radio emission. I have no special program or hardware for that purpose. Why is that possible? —Preceding unsigned comment added by Mr.K. (talk • contribs) 12:10, 7 September 2008 (UTC)

Could be a lot of things, more information is needed to answer fully. You don't say whether it is broadcast radio you are hearing or something else. Taxi radios, for instance, are notorious for being badly adjusted and badly shielded and get picked up by all kinds of things. Broadcast transmitters can be a problem if you live near one. Do you get internet from your cable TV company? sometimes cable companies put analogue signals down the same cable and poor filtering and/or earthing could be your problem. Finally, are you sure you have not connected to a radio station with your web browser and just have the volume turned down? SpinningSpark 15:06, 7 September 2008 (UTC)

It's perfectly possible. If the length of the cable is exactly right to make an efficient antenna, then a strong AM radio station can induce enough energy into the wire to be audible through the speaker. I've had it with an MP3 player and a pair of headphones - so it's not just leakage from cable TV. You can probably get rid of it by shortening or lengthening the cable - perhaps by coiling up any unused length. If all else fails, go to your local Radio Shack (or local equivalent) and buy a "Ferrite bead" and thread the cable through it a couple of times - that'll usually fix the problem. (You see quite a few computer-type cables with ferrite beads built into them for this exact reason.) SteveBaker (talk) 18:34, 7 September 2008 (UTC)

A connection or plug which is not a good solid metal to metal jint, like a loose conection with a bit of corrosion, can easily act as a rectifier, just like a crystal radio or a Coherer. It does not need to be tuned to a particular frequency, but could output the audio of the closest/strongest transmitter through the speaker, with no amplification needed. The distributed capacitance of the wires is enough to create an audio signal with the accidental rectifier of an imperfect metallic junction. I had a stereo speaker once that did this. See also the "foxhole radio" example at [22] on Youtube. Edison (talk) 20:18, 7 September 2008 (UTC)

Lucille Ball (of "I love Lucy" fame) claimed that she had a loose tooth filling that acted as a radio receiver and resulted in music playing in her head. She claimed (bizarrely) that she had on one occasion picked up the sound of morse code - which eventually turned out to be a Japanese spy's radio transmitter located somewhere close to the LA studio where she was working. SteveBaker (talk) 02:52, 8 September 2008 (UTC)

Actions of people with mental illnes or people using drugs

Do mental illness and drugs only take away the constrains to do something or do we come to new ideas in these circunstances? —Preceding unsigned comment added by Mr.K. (talk • contribs) 12:16, 7 September 2008 (UTC)

Well I don't know about mental illness except that in most cases people with it don't have any new ideas that are worth anything to them or others. The idea that insanity is linked to genius is, in all but a handful of cases, totally false.

As for drugs. When on drugs it is common to think that one is getting a flood of new ideas. But in a more sober light most of these are pretty stupid, unoriginal, and uninspiring. I am dubious of the notion that people on drugs think about the world with any more clarity than those not on drugs. It is certainly true that one gets lots of notions. But most of them really aren't anything worth writing home about. There are of course rare exceptions (e.g. it has been said that Kary Mullis claimed to have been inspired to create PCR while on LSD). --98.217.8.46 (talk) 14:07, 7 September 2008 (UTC)

I disagree with User:98.217.8.46. People with manic-depressive disorder are notoriously super-creative when they are in a manic phase. Sadly, they pay for it in their depressive periods - but there is no question that some of the greatest minds in history have been manic-depressive. Similarly, people (like myself) with high-functioning Autism or Asperger's have long been known to be unusually creative in the extremely narrow areas that interest them. So there is no doubt that some conditions of "mental illness" are certainly able to cause new ideas that are extremely worthwhile to others. So let's dismiss what 98.217.8.46 said and try to answer the original question.

Some drugs act like natural chemicals that are in the normal brain - things like beta-blockers which are known to improve people's ability to pass exams by calming them down. It's hard to imagine that these wouldn't cause new ideas to form that otherwise would not. Not being a nervous wreck clearly improves thinking ability - which clearly causes new ideas to form. On the other hand, many "recreational" drugs operate by basically trashing your brain - wrecking the delicate neural sheaths and basically "shorting out" your neurons - and (predictably) causing all the things that make people on those drugs seem so stupid or perhaps comical. So it's hard to make a general statement - other than that there are some occasions with some drugs where new ideas might appear that would not otherwise have done so.

I guess the hard part about this question is whether that "takes away the constraints to do something". I don't think that's quite the right reason. Alcohol certainly makes people less inhibited ("takes away constraints") - but lots of drugs and mental illnesses do the complete opposite. My condition (Asperger's syndrome) certainly adds a lot of constraints (inability to handle body language and appropriate eye contact for example) - but on the other hand it removes a constraint that "normal" people have about spending LONG periods of time studying a narrow topic. When I was writing the Wikipedia article about the Mini Moke - I knew relatively little about this rather obscure car - I bought literally every single book ever published about it - I scoured eBay for old car magazines that discussed it - and I basically geeked-out on reading this pile of material - 8 hours a day for an entire week. I know now more about the Mini Moke than almost anyone on the planet! (Trust me - this is not very useful) You'd have gotten bored out of your skull by the end of the first chapter. So my condition resulted in a constraint being removed. But whether that resulted in new ideas is certainly rather debatable. (Well, I did get the new idea that I want to spend $10k importing a rusted out Moke from Australia and spending months fixing it up because they are so amazingly cool...but (for example) my Wife didn't find that idea "useful" - so it hasn't (yet) come to fruition.)

So there is no doubt whatever that some drugs and some mental conditions DO cause new ideas to form - whilst others to the exact opposite. I don't agree with the "why" of it though - and it's certainly not true of all mental conditions or all drugs - so we should be careful not to generalize.

SteveBaker (talk) 18:23, 7 September 2008 (UTC)

I think the problem here is with the definition of mental illness. Perhaps it is more appropriate to use the word “condition” in cases where there is a possibility of a positive effect. --S.dedalus (talk) 23:18, 7 September 2008 (UTC)

Well - I don't know - use whatever word you like, it doesn't really change the fact that many people who are practically crippled by their "problem" can also gain huge benefits from it - intellectually. Call it a problem, a condition, and illness, a blessing or a curse...that doesn't really change anything. Personally, if it's something you can cure - it's an illness. You can pretty much cure manic depressive syndrome with drugs - but the cure (for some of those people) is not always something they want. Very few Asperger's people want to be "cured"...I'd certainly resist it very strongly. SteveBaker (talk) 01:32, 8 September 2008 (UTC)

I'm not very surprised to hear that you have Asperger's, Steve; you have a kind of a pedantic approach to things that I have experienced with others with that condition. (It's probably a pretty useful trait for someone working the Ref Desk, too.) Speaking from my own personal experience, I've had my struggles with depression, and I can certainly attest that the manic phases can be very creative. I've kind of mellowed out over the years, though, mostly by learning to read my own signals and adjusting my behavior and circumstances to avoid high-risk situations that trigger unwanted reactions. (In simple terms, this means that, for example, I try to avoid letting myself get sucked into cycles where I don't sleep nearly enough, if at all, and work for extended periods of time until I crash. It sounds stupidly simple, I know, but it took me a bunch of years to figure that pattern out well enough to anticipate it.)

Anyway, my point is, I do a lot of creative work, and some of it has certainly been produced in the more manic periods of my life. Good work, too. I'm tempted to say that those are exceptionally creative phases, but honestly, I don't know whether that's just a mindset where I work hard and the creativity is so strongly present simply because it's contrasted by periods where there isn't any. These days, when I'm more balanced about that stuff, I don't really feel any less creative. All in all, considering that there have been periods when I've been entirely uninterested in, well, most everything in my life, I'd say that on average, I'm probably getting more done now than before.

To kind of answer the original poster's question, I definitely think that it's possible for one to be very creative when under the influence of drugs or suffering from a mental condition, possibly more so than when one would be otherwise -- but I think it would be a mistake to assume that the drugs or the condition themselves are the cause, rather than a catalyst. -- Captain Disdain (talk) 09:39, 8 September 2008 (UTC)

Obviously whether mental illness has creativity to it depends on one's definition of mental illness. I wasn't putting Autism or Asperger's in that category; I was thinking of depression and schizophrenia in particular (and I write this as someone who has done a lot of work relating to the history of mental health—for every occasional "genius" who suffers from these particular conditions you have a thousand people who can barely get out of bed, people who in a pre-pharmacological time would have to spend their whole lives in institutions). I suppose the main take-away point here is that one's definitions are rather important. --98.217.8.46 (talk) 13:50, 8 September 2008 (UTC)

Racism or learning from experience?

Moved to Humanities desk at Wikipedia:Reference desk/Humanities#Racism or learning from experience?

xenophobe in ethimological sense

If a person has a phobia against foreigners (xeno), could he be called xenophobe? Does these king of people exist? —Preceding unsigned comment added by 88.6.158.246 (talk) 12:54, 7 September 2008 (UTC)

Yes, yes. See Xenophobia. --98.217.8.46 (talk) 13:39, 7 September 2008 (UTC)

Although, the term is usually used to describe a dislike of foreigners, rather than a fear of them, per se. --Tango (talk) 23:02, 7 September 2008 (UTC)

I suppose the question was that if there is a psychological condition called "xenophobia" similar to agoraphobia and other phobias. —Preceding unsigned comment added by Mr.K. (talk • contribs) 18:39, 8 September 2008 (UTC)

Yes it commes from the greek words xenos (ξένος)-stranger and phobia (Φοβία)-fear. the oxford dictionary contains the word xenophobia and it is the psycological condition of fearing-hating stranges... for example see the rednecks in america!!!

79.166.35.82 (talk) 16:11, 9 September 2008 (UTC)

Beta decay, the weak force and W- boson mass

If beta minus decay occurs by a down quark changing into an up quark by the emission of a W^- boson, how can a W^- boson have a much higher mass than the entire decaying neutron? -- Aeluwas (talk) 13:34, 7 September 2008 (UTC)

Virtual particles in a Feynman diagram don't generally satisfy E² = p² + m². They're said to be "off the mass shell." -- BenRG (talk) 14:04, 7 September 2008 (UTC)

Specifically, this is allowed if $E\cdot t\lesssim \hbar$, where t is the life time of the particle (i.e., the duration of the decay process). --baszoetekouw (talk) 19:30, 7 September 2008 (UTC)

The Bernoulli family and the "Bernouilli" one

Apparently the second spelling of their family name is incorrect, but I've stumbled upon that spelling many times, especially in Spanish publications. Is it just a bad habit that has become widespread in the Spanish community or am I missing something? --Taraborn (talk) 18:03, 7 September 2008 (UTC)

I don't know about this particular family, but I'd hesitate to tell other people they can't spell their own names. Spelling is an arbitrary thing; spelling of names from other languages or countries even more so, as Ellis Island can attest. I've seen highly amusing rants about "MacDonald" being the only correct spelling -- odd for a name that began as Mac Dhomhnuill. I'm sure that type of certitude gets all the consideration it deserves from Godfrey James Macdonald of Macdonald, 34th hereditary chief of Clan Donald. --- OtherDave (talk) 19:52, 7 September 2008 (UTC)

Bernouilli certainly seems to be common, and not just in Spain; Wikipedia has it as a redirect. this errata list shows "Bernouilli" being corrected to "Bernoulli" which, while not definitive, is certainly indicative that it is an error. SpinningSpark 20:07, 7 September 2008 (UTC)

I'd be hesitant to claim something as a definite error for a family whose country has at least four languages and who lived very early on in the emergence of the idea that every word has one correct spelling. Bernoulli is certainly the standard spelling in modern English though. Algebraist 00:10, 8 September 2008 (UTC)

Stroke article in The Lancet

There was recently (May 10th) a really good article on stroke in The Lancet. It can be found here: doi:10.1016/S0140-6736(08)60694-7 Would anyone be able to provide me with a copy, preferably digital? —Cyclonenim (talk · contribs · email) 20:18, 7 September 2008 (UTC)

Try at WP:WRE. It's a great but underused resource. --Shaggorama (talk) 22:34, 7 September 2008 (UTC)

September 8

Significant figures - fun stuff

If you're a professional scientist, you're probably laughing right now, but sadly I am but a poor high school student and sig figs are imprinted on us as the universal method of...well, messing up otherwise perfectly functional math. Anyway, I have a quick question regarding sig fig arithmetic: Suppose you have two numbers of equal orders of magnitude and the same number of sig figs, and you subtract one from the other. How many sig figs does the answer have? For example:

0.125 g - 0.106 g = 0.019 g

Then you go off and use the 0.019 g in other calculations. Do you treat it as 3 sig figs (because the data used to obtain it had 3) or 2 (its face value)? In other words, are sig figs based on the numbers you put in, or the lowest point achieved during calculations? Another example:

25.983 amu - 24.986 amu = 0.997 amu

Again, are there 5 or 3 sig figs? Thanks, FlamingSilmaril (talk) 00:03, 8 September 2008 (UTC)

What you wrote as an answer is correct. The rule that the answer should have the same amount of SigFigs as the number with the least amount of SigFigs only applies when you are multiplying or dividing. When adding or subtracting, the answer should have the same amount of decimal places as the number with the least amount of decimal places.

So for the first one, the answer is "0.019" and has 2 SigFigs. For the second one, the answer is "0.997" and has 3 SigFigs.

Acceptable (talk) 00:42, 8 September 2008 (UTC)

Unfortunatey, that rule is too simplistic and ends up with false precision. --Tango (talk) 00:45, 8 September 2008 (UTC)

It might be best to thing of it in terms of the size of the possible error. 0.125 means 0.125 +/- 0.0005 and 0.106 means 0.106 +/- 0.0005, so the sum becomes (0.125 +/- 0.0005) - (0.106 +/- 0.0005), the maximum value that could give is 0.1255-0.1055=0.200 and the minimum is 0.1245-0.1065=0.0180, so the answer is 0.019 +/- 0.001. That can't be written in terms of significant figures. If we say "0.019 (2sf)" then we mean 0.019 +/- 0.0005, which is more precise than what we actually have, so that would suggest we need less significant figures, so we try 1sf, which gives 0.02 +/ 0.005, which is less precise that what we actually have. Therefore, the best we can do (if you want to stick with significant figures) is to quote it as "0.02 (1sf)", but you've lost some precision by doing that. To quote it was "0.019 (2sf)" (or, even worse, to 3sf) would be false precision, so you certainly can't do that. If you need a final answer in terms of significant figures, your best option is to do all the calculations using figures as precise as you can and carrying through all the +/- terms as I did above and then round the final answer to the most significant figures you can justify (this will almost always be less than what you started with). --Tango (talk) 00:45, 8 September 2008 (UTC)

The +/- notation certainly seems like a more accurate way to depict uncertainty, but for now I have to use sig figs. What was confusing me was that 0 in the tenths place - the tenths place was significant in both the input data values, but I guess it sort of drops out when you subtract? FlamingSilmaril (talk) 01:11, 8 September 2008 (UTC)

If you don't want to go through the hassle of carrying through all the errors, you should at the very least knock one sig fig off the final answer, it's virtually never going to be accurate to the same as you started with (so in your first problem above, state the answer as "0.02 (1sf)" (you don't have to specify the "(1sf)" part, it's implied by the fact that you haven't written any trailing 0's, but it might be best to just to make it clear that it's an approximate answer). The error represented by a given number of significant figures depends on the magnitude of the number, when you subtract two numbers that are close together you get a number with a smaller magnitude, which means the same error is represented by fewer significant figures (however, the actual error is greater than the error you started with, hence the loss of an extra digit). --Tango (talk) 01:23, 8 September 2008 (UTC)

Just say no to sig.figs. It's useful as a very rough rule to try to avoid quoting more digits of precision in your answer than in your source data. But please - only use that for "back of envelope" calculations. For anything formal - or anytime the answer matters - you have to do as User:Tango says - you have to track the maximum and minimum possible value for every number in your source data and carry that error range through every step of your calculation.

For some bizarre reason, highschool teachers have got it into their heads that the sig.figs thing is a vitally important, cast-iron technique that all scientists use all the time - so it has to be drilled into the heads of their victimspupils. In truth it's a kinda scruffy rule of thumb that basically stops people from claiming far too much precision in their results. It allows you to glance at a calculation someone gives you and be immediately suspicious of it if there are more digits in the result than in the input.

Furthermore, you need to know what the nature of those errors are. Suppose you're taking the average of ten numbers. If those numbers came from (say) a human measuring something with a tape-measure - then the errors are likely to be random - and normally distributed. Calculating the average of 10 numbers increases your precision because those errors average out. But if the error came about because the person was using a computer program that truncates input data instead of rounding it - then all of the error is in the positive direction and the average of those ten numbers is no more accurate than the input data. It's a very subtle business - and not one that I trust to these rules put out by well-meaning math and science teachers to schoolkids.

Of course, most kids fall asleep during this stuff because it seems so divorced from reality. A practical anecdote might help here: I'm in computer graphics for video games - and having a really good feel for the size of the errors and the sensitivity of the math to those errors ends up being critical. We deal with colors on the screen of your computer that are integers in the range 0 to 255 - about two and a half "sig figs". But the math that determines how light reflects off of shiney objects entails taking the direction of the incoming light, the surface direction and the direction of the eye/camera, then you calculate the cosine of the difference between the angle of incidence and the angle of reflection and raising it to the power of the shininess factor. OK - but the shininess factor is often a big number - 20 to 200 might be typical. Well, when you subtract two numbers that are similar in size - then raise the result to the power of 200 - the number of sig figs you need in your input data skyrockets! We typically need numbers that are accurate to one part in a billion to get good results - so the input data needed something like 8 or 9 sig figs. Urgh! On the other hand, if the object isn't shiney - so the coefficient of that calculation is more like 1 - then the input data only needs about 3 sig figs. We can take practical advantage of that by storing and handling the data to rougher precision for dull objects than for shiney ones. That means we need to send less data between the computer and the graphics card for dull objects - that means we can draw a lot more dull objects than shiney ones. THAT means that we can tell our artists that if they have their monsters NOT be slimey - they can have more monsters.

Proper error understanding means more monsters!...Math in action where it matters!  :-)

SteveBaker (talk) 01:24, 8 September 2008 (UTC)

Unfortunately, he can't just say no, he has no choice but to do his homework in the way he teacher wants it done. Sig figs are useless for doing any kind of calculations, where they are useful is in writing down uncertain numbers. It's much quicker to write "52.50" and have everyone know it means "52.50 +/- 0.005" than write "52.50 +/ 0.003", so you do it even though you're losing some precision. It's a good rule of thumb for knowing you precise your starting values are and for stating how precise your final figures are, but for everything in between, they're useless. They're often useless even for that, as an example I just came up with shows: Consider the sum 135+120, both figures are to 3sf. If we work out the correct answer we get 155 +/- 1, if we want to save space by not explicitly writing the error term we need to find a number of sig figs that doesn't mean we end up with false precision. 3sf clearly isn't going to do it, but it turns out neither does 2st since rounding to 2sf would give us 160 +/- 5 (don't get me started on how to round 5's!), which means the answer is somewhere between 155 and 165, but the answer might actually be 154, so we have to go all the way to 1sf and say it's 200 (1sf), which is correct but 50 times less precise than it could have been, so the number is probably completely useless. --Tango (talk) 01:55, 8 September 2008 (UTC)

I understand - and I agree. 100%. I just don't want students to graduate from high school imagining that the sig figs approach is any more than a rough rule of thumb. It's not taught that way - which is a major problem. When people start telling me that this is some kind of solid rule that "scientists" use - I get upset! In my job, having a solid feel for where precision get's lost - how to avoid losing it - where you need it and where you don't - is literally the difference between a great-looking video game and a terrible one. On the other hand, when someone on the WP:RD says that 220 million tons of coal is enough to last the UK for 400 years - and I do the math and wind up with just one year, it's nice to NOT say 0.845 years - and it's nice to know that it really couldn't really be 400 years because of roundoff errors - but it's a 'back of envelope' calculation and it's really not necessary to carry through anything more than a rough idea of the numbers of sig figs I'm using. So - as I said - the sig.figs approach is fine for 'back of envelope' calculations - but useless for serious work where the results actually matter. If an engineer designs a bridge that I have to drive over...I want accurate error tracking! SteveBaker (talk) 02:43, 8 September 2008 (UTC)

Ya gotta love WP:RD...in three hours I've gotten more helpful info on precision than in a year's worth of high school chem. Thanks a lot, everyone. This was very insightful! FlamingSilmaril (talk) 03:05, 8 September 2008 (UTC)

Thanks for your kind words - but PLEASE learn what your teachers teach - you need to get through exams, and if they require you to learn a pile of crap - go learn the pile of crap. Feel free to forget it later - but you need those grades! SteveBaker (talk) 17:29, 8 September 2008 (UTC)

Yeah, well said, Steve... I remember when I learned the real relationship between sig figs and careful error propagation, I thought, "I am way too old to be learning this for the first time." --Allen (talk) 07:26, 8 September 2008 (UTC)

Yep - me too. SteveBaker (talk) 17:29, 8 September 2008 (UTC)

Unfortunately, once you make it out of high school and into the realm of "professional science," there are all kinds of new silly specifications such as font-size and formatting minutia necessary for paper-publishing (which is in itself a dark and horrible cavern). It seems the same people who sit on school boards determining that SigFigs are relevant to high-schoolers are also sitting on paper-reviewing committees. I recommend obtaining and thoroughly learning a good word-processing suite which can handle formatting AND sig-figs so you can focus on the scientific task! As far as your data-processing, most of us do not have the constant need for real-time performance that Steve does, so we can perform over-kill and use more precision than necessary. But this is hardly a substitute for understanding the mathematical concept of error propagation. Even 32 or 64-bit calculations will only return what you asked them to return. Nimur (talk) 14:24, 8 September 2008 (UTC)

Or work in a discipline that uses software designed for scientific writing, rather than fighting with an office suite... -- Coneslayer (talk) 16:17, 8 September 2008 (UTC)

This stuff isn't only about writing research papers. Professional scientists do lots of actual practical work without ever writing a single paper in their entire lives. The discipline of maintaining correct precision throughout your calculations isn't just about getting your paper accepted - it's also about not having your bridge collapse - or (as in my case) making cooler graphics for your Xbox. That's an important thing - so many people do math and science in school, fondly imagining that they'll NEVER need to use any of this stuff in "real life" - when in fact, they really should. SteveBaker (talk) 17:27, 8 September 2008 (UTC)

If you are adding ten numbers, and each is +/- 0.1, why would you assume that the sum could be off by 1.0, which is the sum of the uncertainties? Wouldn't it make more sense to treat each one as a normally distributed uncertainty and take the square root of the sum of the squared errors? This would be the square root of 10 times 0.1² or .32? Edison (talk) 19:00, 8 September 2008 (UTC)

It depends on where your data comes from. For example, I once worked with some data-collection software with a strong bias for "+" in its data, so a total error of +1 was far more likely than a total error of -1 --Carnildo (talk) 23:25, 8 September 2008 (UTC)

Sometimes you do do things like that, it depends on the type of measurement. If the error is normally distributed, then you're right, but sometimes it isn't. One (rather bad) example would be where the error comes from the data having been previously rounded, then "+/- 0.5" doesn't means "there's a 68% chance it's between 0.5 less and 0.5 more" it means there's 100% chance, and the error isn't normally distributed, it's uniform. In that case, ten lots of +/- 0.1 does make +/- 1. (That's a bad example because you should never use data rounded off to a precision so low that it's a significant source of error, but there might be the odd occasion where you have no choice.) --Tango (talk) 09:56, 9 September 2008 (UTC)

Significant figures should be thought of as a way of introducing accuracy; it is not intended to be a rigorous mathematical tool. Perhaps sig figs are best thought of as another name for relative accuracy--that is, the error margin of a certain value compared to the value itself. To show how the relative accuracy is useful, consider a census. If a tiny community's population is reported to within 5 individuals, nobody would be impressed, but it would be shocking if the population of the entire U.S. is reported to within 5 individuals.

The example 0.125 g - 0.106 g = 0.019 can be thought of as: (1) There are two measurements that are reasonably accurate to within a certain absolute error margin. (2) When subtracting one number from another, the result should have double the absolute error margin. (3) Since the absolute error margin has been doubled and 0.019 is much smaller than 0.125 or 0.106, the error margin makes up a larger percentage of the value. (4) Intuitively, 0.019 should have less sig figs than the two original values.

I remember being taught sig figs in science class and calculating the actual error margins out of curiosity. The concept really is almost useless, and for that reason my teachers never required us to round answers appropriately on evaluations. It's useful to know that writing 2/3=0.6666666666666666666666666666666666666666666667 is not necessary, but that's likely as far as your chemistry teacher is going to go. --Bowlhover (talk) 05:00, 9 September 2008 (UTC)

This opens up another whole can of worms of course. If your data truly does have a normally distributed error pattern - then statistically, one sample can have an error that's a million times bigger than the "typical" value and even though you're averaging 10,000 samples together, that one outlier is enough to blow your error estimates off the chart. Worse still, if you multiply something with a normally distributed error by something else with a normally distributed error - you end up with a gaussian-squared error profile. Tracking the NATURE of the error through all of your math becomes a major mathematical nightmare. But at this point, you're more into the area of full-blown statistics than simple error tracking. However, even in relatively simple cases, this kind of thing becomes an issue. The round-off error in a floating point number in a computer depends on the magnitude of the number - the round-off error in an integer does not. SteveBaker (talk) 15:55, 9 September 2008 (UTC)

Dark skin and dominant/recessive traits

I know that darker eyes are a dominant trait contrasted with lighter eyes like blue eyes, which is a recessive trait. But what about darker skin? Is that a dominant trait as well contrasted with lighter skin? Is lighter skin a recessive trait compared with darker skin? ScienceApe (talk) 00:03, 8 September 2008 (UTC)

Unfortunately, it's not that simple, since there isn't just "dark skin" and "light skin", there is a whole range of colours. If someone with very dark skin and someone with very light skin has child, it will generally have skin somewhere inbetween. Talking about dominant and recessive traits only really works when the trait is governed by a single gene, which isn't the case with skin colour. --Tango (talk) 00:30, 8 September 2008 (UTC)

It's not even actually the same with eye color, which is controlled by a number of genes but can usually be simplified. --98.217.8.46 (talk) 13:24, 8 September 2008 (UTC)

I haven't read it, but we have Skin_color#Genetics_of_Skin_Color_Variation. --Allen (talk) 12:01, 8 September 2008 (UTC)

Robustness or lack thereof in "B-rex" (dinosaur question)

I know the validity of the robust/gracile morphotypes is uncertain, but does "B-rex" (MOR 1125)--the Tyrannosaurus specimen that was discovered to have medullary bone--fall into the robust or gracile morphotype? I know the robust morphotype is generally considered as more likely to be female, but am curious as to whether or not MOR 1125 supports this or not. 75.211.143.162 (talk) 01:47, 8 September 2008 (UTC)

Is this radiant energy exploitation possible?

1) Let there be a plane where the temperature is the same on both sides.

2) Let the plane have a hole in it. lets call one side the sending side and the other the receiving side.

3) Assume that there is a device on the sending side that will redirect and focus all ambient radiant energy that arrives in its collector and that its collector is the same size as the hole. Therefore the amount of radiant energy passing through the focus of the device would be the same as that passing in one direction through the hole in the plane.

4) Assume that this device is so arranged as to focus its output on the hole so that its focused energy is radiated through the hole in addition to what normally would pass through the hole.

5) In this case the receiving side should increase its energy (temperature) levels until its emissions through the hole matched those of the sending side. The energy (temperature) levels of the receiving side would be increased until its emissions matched those of the IMPLIED energy (temperature) levels of the sending side.

This is of course completely contrary to the 2nd law of thermodynamics as we would be moving energy from a colder to a hotter body and we would be decreasing entropy at the same time.

Some calculations -

Assume temperature of both sides starts at 300K (27 C) and a hole size 1 cm.

Therefore the amount of radiant energy passing normally through the hole is -

300^4 /10000 = 810,000 energy units (units of measure are not important because we work back to temperature)

We double the amount of energy passing through the hole by using the device.

810,000 * 2 = 1,620,000 energy units

The implied temperature of the energy passing through the hole is therefore

SQRT(SQRT(1,620,000*10000)) = 356.76K (83C)

Therefore the temperature of the receiving side will have to increase over time to 356K to balance the amount of energy passing through the hole.

Can you help and point out what I am missing? Or perhaps this actually works and for some reason that I cannot see, I don’t actually violate any laws of science.

Please give me your comments.

Thank you.

John —Preceding unsigned comment added by Habanabasa (talk • contribs) 06:49, 8 September 2008 (UTC)

You cannot have your assumption 3 device, which in itself violates the second law (the directed radiation has less entropy than the original undirected radiation). --Stephan Schulz (talk) 06:57, 8 September 2008 (UTC)

Sounds a bit like Maxwell's Demon. DMacks (talk) 16:57, 8 September 2008 (UTC)

I agree with Stephan - step 3 is impossible - this "focussing" device breaks at least the second law of thermodynamics - since that's bogus, the whole concept fails. Maxwell's Demon is a more subtle problem - and the reasons why it fails are really rather subtle. SteveBaker (talk) 18:25, 8 September 2008 (UTC)

will the world ever end?

i would like to know if the worldwill ever end because people have been saying we are going to go through the black hole. is it true? —Preceding unsigned comment added by 124.179.167.13 (talk) 08:35, 8 September 2008 (UTC)

Probably not, no. Unless you hear about it everywhere - all newspapers, all TV channels etc - then it's most likely a hoax. The life on Earth will probably end in a few billion years, though, when the sun burns out and expands. -- Aeluwas (talk) 09:12, 8 September 2008 (UTC)

You're probably referring to the (fairly tiresome) controversy surrounding the Large Hadron Collider. No, it's not true; you can read more about the LHC and black holes here. In short, though: there's no reason to believe that there's any threat to Earth. Well, not from the LHC, anyway. (Also, you might want to think this through a little bit: if the world was known to end real soon now, don't you think there'd be some kind of serious discussion about it on a level that you couldn't help but notice instead of vague rumors and whatnot?) -- Captain Disdain (talk) 09:17, 8 September 2008 (UTC)

Certainly the world will eventually end. It's not likely to be a black hole that does it - but our own sun. As the sun starts to run out of fuel, it will gradually expand outwards, getting cooler and redder - swallowing up Mercury, then Venus and possibly also the Earth itself. But even if we don't get swallowed by the sun, the heat will boil away our oceans and probably blow away our atmosphere - eventually melting the rocks and everything mankind has ever worked for. Fortunately, the sun is barely halfway through it's fuel supply so this horrible event is many billions of years away. So mankind has plenty of time to think about building gigantic spacecraft and to start finding a younger star to live nearby. SteveBaker (talk) 17:20, 8 September 2008 (UTC)

There is an article on the end of the world which talks about even more ideas. Adding humans to the planet greatly increases the chances that something diffferent will end the world. Even if the LHC cannot destroy the earth, a hypothetical man made black hole that is big enough hypothetically could. Graeme Bartlett (talk) 21:21, 8 September 2008 (UTC)

Sure, there are all kinds of hypothetical ways we could destroy the world. A black hole is one of the more unlikely ones - nuclear war is several orders of magnitude more likely, for example. --Tango (talk) 09:59, 9 September 2008 (UTC)

It depends on what you mean by "end of the world". End of human civilisation? Probably in the next few million years. End of life on Earth? Likely to take millions, if not a few billion, years. End of the Earth as a discernable entity in space? Wait for the Sun to go nova, as described above. End of the universe? See what the article says. But destroyed by a microscopic black hole, or by an amazing planetary alignment, or just because we hit a date in some calendar that happens to coincide with the end of a cycle? Probably not in my lifetime. Confusing Manifestation(Say hi!) 23:09, 8 September 2008 (UTC)

Our sun will not "go nova". It will expand into a red giant and then collapse into a white dwarf. You may also want to read up on the difference between a nova and a supernova. --Tango (talk) 09:59, 9 September 2008 (UTC)

No, it won't produce a nova - for that you need a binary star. But at the end of the Red Giant phase, there would be a "helium flash" - which would be just as exciting as a nova if you happened to be nearby! The hydrogen in stars the size of the sun gradually runs out - forming helium as it does so - and the core of the star collapses while the outer layers are expanding to form the red giant which is what will kill the earth. When the core has collapsed enough, (long after the Earth is toasted to a cinder) the sun will reach a temperature that is enough to start a helium fusion reaction (producing carbon). That's not a gradual thing - it happens for just a few seconds - and during that time the star pumps out a hundred billion times it's normal amount of energy! It's not a nova - but it's pretty damned impressive! This blows off the outer "red giant" stuff to form a "planetary nebula" while the core collapses into a white dwarf which eventually starts fusion reactions with carbon and onwards to higher and higher atomic weight byproducts. However, that exciting "helium flash" won't happen until the Earth is long-gone. SteveBaker (talk) 15:34, 9 September 2008 (UTC)

sufuric acid

how can i prepare a solution of 0.13 M of sulfuric acid —Preceding unsigned comment added by 213.207.34.76 (talk) 08:38, 8 September 2008 (UTC)

Put 0.13 mol of sulfuric acid in a 1l flask and fill up with water. (molar mass of sulfuric acid is in the table at the artikle)--Stone (talk) 09:41, 8 September 2008 (UTC)

Don't do that! For safety reasons, it is very important to add sulfuric acid to water and not water to concentrated sulfuric acid. As I understand it, putting water into concentrated acid can cause the acid to spatter. Wanderer57 (talk) 13:06, 8 September 2008 (UTC)

... as shown in this sign, ALWAYS add acid to water. Nimur (talk) 14:08, 8 September 2008 (UTC)

Always add acid? I often prefer my water acid-free -- MacAddct  1984 ^{(talk • contribs)} 14:58, 8 September 2008 (UTC)

The 'add acid to water - not water to acid' rule is important. The reason is that the resulting liquid can indeed splash, 'fizz' and splatter. If you screw up and add water to acid then the liquid that's splattering is concentrated acid...not good. If you do it the right way around and pour the acid into water - then the splattering is of water - or at least, very dilute acid. But even when you do it right - you have to be really careful. SteveBaker (talk) 17:12, 8 September 2008 (UTC)

Also the heat of solution seems less sudden. Acid-to-water, a small amount of acid dissolves, so a small amount of heat in a large container of water. Water-to-acid, lots more energy released by the solvation and for ultimately dilute solutions there is usually a very small solution volume with all that energy, so lots more heat. I've cracked several flasks by adding water to acid and by not using sufficient cooling. DMacks (talk) 17:35, 8 September 2008 (UTC)

Sulfuric acid is usually provided as a concentrated solution in water. (Usually 18 M, although your stock solution may be different - examine the container to be certain.) After determining the volume of dilute solution you need, calculate the number of moles of sulfuric acid you need for that volume (for 1 L, it's 0.13 mol; for 100 mL, 0.013 mol). Then determine the amount of concentrated solution you would need to give you that molar amount of sulfuric acid. (Once you get the hang of it, you can save time on the calculation by using the c₁*v₁ = c₂*v₂ trick.) Measure that out, and add it to almost-but-not-quite the amount of water you would need to bring the total volume to the desired volume, and once mixed bring the solution to the final volume with a small amount of water. (The convoluted procedure is needed because volumes aren't always additive.) This proceedure should have been explained in your beginning laboratory course - if you are unsure about your technique, I would recommend seeking skilled supervision before working with concentrated acids (... and then ask them to show you how to do it). -- 128.104.112.147 (talk) 15:48, 8 September 2008 (UTC)

TV detector vans

As many will be aware, everyone in the UK who watches television is legally obliged to own a TV licence. The money from these funds the BBC, since it is a non-commercial broadcaster. Anyway, enforcement of TV licence ownership is a big issue; see Television licensing in the United Kingdom#Licence fee enforcement. As that article states, TV detector vans are used in an attempt to trace homes that are watching TV without a licence. But there have long been suspicions that these vans are fake and just employed as a deterrent. This article states that the technology used by the vans is top secret. So, are TV detector vans really able to detect when a TV is on in a house? And what is this supposedly top secret technology? --Richardrj ^{talk email} 08:59, 8 September 2008 (UTC)

The "top secret" technology is most likely nonsense perpetuated from a simpler and more credible credulous age because:

1. I don't see how any "detector van" can possibly detect people who are watching non-broadcast television e.g. via cable or the internet (but, yes, they do still need a television licence).
2. This information leaflet from the BBC Licensing Authority says "TV Licensing’s policy is to visit all addresses where people inform us that no television is in use at the property" and "TV Licensing’s policy is to visit all addresses where people inform us that a black and white television is in use at the property" (and it makes no mention at all of detector vans !). So if the Licensing Authority makes follow-up visits at all properties which claim they do not need a licence or claim they only need the cheaper black and white licence, why invest in complex and expensive technology as well ? Gandalf61 (talk) 10:39, 8 September 2008 (UTC)

Do you mean a more credulous age? Algebraist 10:43, 8 September 2008 (UTC)

Yes, indeed. Gandalf61 (talk) 10:51, 8 September 2008 (UTC)

You can't generally do it sitting in a van, but it is fairly easy to send an electrical pulse down a cable line and estimate the number of splits and connected devices by measuring the reflections that come back. It only works if the number is small, so you need to be close to the end user, but it is a fairly standard technique for detecting illegal cable taps. Broadcast would be far harder, I'd imagine. (Unless the secret tech is "binoculars" and you are peeping in people's windows.) Dragons flight (talk) 10:46, 8 September 2008 (UTC)

Re. 1, investigation of the TV licensing authority website FAQ reveals that you don't need a license if you don't watch television as it's broadcast. Currently, this even means that you can watch the BBC iplayer without a license (as it only has programmes on-demand). [23] AlmostReadytoFly (talk) 10:55, 8 September 2008 (UTC)

I'm fairly sure it does streaming radio but if the BBC ever gets it into their head that they can charge me a licence fee just because I own a PC capable of internet access and could potentially go to their iPlayer website they can sod off. Its one thing when there are 3 out of 5 channels so you don't really have an excuse of "I don't watch the BBC channels" because you're likely to, but when its several billion webpages it gets silly TheGreatZorko (talk) 10:59, 8 September 2008 (UTC)

It does indeed do streaming radio, but the radio license has been abolished. I'm not sure how they would plan to cope with all the people telling them to sod off if they introduced live internet TV broadcast. I wouldn't be surprised if that's one of the reasons it hasn't happened. AlmostReadytoFly (talk) 11:13, 8 September 2008 (UTC)

Um cable? Why would they have to worry about cable? All they need is for the cable TV network to give them a list of subscribing households for them to check against their list of TV licensees. If someone has cable but not a TV license, well just pay them a visit... Same with paid satellite. I'm not sure if you need a license if you only use FTA satellite but even if you do, it's not that easy to hide a satellite dish so even if they can't detect you receiving satellite TV, they can probably detect your satellite. Nil Einne (talk) 11:37, 9 September 2008 (UTC)

Back to the question... It is possible to detect a flyback transformer in use. Until the current flat-panel televisions became popular, the flyback transformer was a very important part of all televisions. Detecting it is nearly identical to how (good) radar detectors, laser detectors, and anti-radar detectors work. They detect the emission of radio frequencies from the electronics. In the U.S., all electronics that I see have an FCC sticker on them that states that the radio emissions are within FCC guidelines - which basically states that it is emitting some sort of radio frequency. Usually, it isn't strong enough to be detected more than a few inches from the device. With the older televisions, I tested the range and was able to detect a television turning on and off from across the street. It was almost as powerful a signal as blenders and vacuum cleaners. Then, my whole "lets have fun with radio signals" ended when I was caught driving through neighborhoods and opening all the automatic garage door openers. -- kainaw™ 12:19, 8 September 2008 (UTC)

Could this principal be used to verify which channel is being watched? The claim was that the detection vans could tell which channel was being watched, since during the days of terrestrial television only two channels were BBC and hence liable for a licence. Jdrewitt (talk) 12:29, 8 September 2008 (UTC)

No - the law has always been that you have to have a licence regardless of what channels are being watched. If you never watch BBC, you still have to have a licence. --Richardrj ^{talk email} 12:41, 8 September 2008 (UTC)

The old analogue method of detecting the local oscillator in a turned on set could determine the channel being watched by the frequency detected. As the oscillator would emit a frequency that was always 39.5Mhz above the tuned in channel a simple bit of arithmetic would pinpoint what they were watching, eg - if a frequency of 793.75Mhz was received, subtracting 39.5Mhz would leave a detected value of 754.25Mhz which lies between the 751.25Mhz - 757.25Mhz band which is analogue channel 56 or BBC1 to you and me. I seem to recall something about the European Court of Human Rights either issuing a ruling or threatening action about this particular data capture as it was deemed outside of the requirements of enforcement to take note of someone's viewing habits. Nanonic (talk) 12:44, 8 September 2008 (UTC)

In this century of the fruit bat, when we now have plasma screens, satellite dishes, cable, digital TV, TiVo and TV tuner cards, I still don't see how it is feasible to remotely detect each and every instance of live TV viewing or recording. Far cheaper and easier to visit the relatively small number of properties that do not have a TV licence - which is what the Licensing Authority actually says it does. Gandalf61 (talk) 13:06, 8 September 2008 (UTC)

Actually, what they say is that they visit all properties whose owners claim not to have a TV (or to have a black and white one only). I can't find anything in that pdf that says what they do if you just ignore their rude and threatening letters; my own very limited experience is that they send more letters and do nothing. Algebraist 13:14, 8 September 2008 (UTC)

My experience is that they send the threatening and rude letters regardless of whether or not you have a TV license, so I'm not sure there's any point in getting on at all. --Tango (talk) 13:22, 8 September 2008 (UTC)

I think the main way they catch people these days is by requiring an address whenever you buy a TV and then checking to see if you buy a TV license (or already have one) within a month of purchase, or whatever. It's not hard to get around that, of course. --Tango (talk) 13:22, 8 September 2008 (UTC)

all this chat about detection is a little bit hypothetical surely. I've happily watched tv without a license for years (shhhhh, it'll be our little secret). I've had a few threatening letters but ultimately Capita (who are the faceless corporation who run the enforcement side) aren't agents of the law and so cannot come into my house without a warrant. Surely, when you get the knock on the door, you just insist they get a warrant then sneak out and hide your TV at your neighbours house? Now that increasing numbers of us live in apartments blocks, you don't even have to put your socks and shoes on..82.22.4.63 (talk) 20:04, 8 September 2008 (UTC)

I believe that the TV licence enforcement people don't need a search warrant. Remember - the UK doesn't have a constitutional right for individuals to not be searched as there is in the USA - in fact, we don't have a constitution. So I believe, the guy will simply enter your home anyway. Plus, if they do detect you are using a TV, that evidence can probably be recorded and used in court without them actually finding the TV set. My father always swore he was going to buy two VCR's - use one of them to record TV shows and the other to play them back into a TV that he'd remove the UHV demodulator from. The result would be that he would not own a device capable of viewing broadcast TV - and would therefore be off the hook legally speaking. Of course, like the rest of us with clever schemes, he just paid up for the license fee.

Of course they need a search warrant. You don't need to have a written constitution to have laws against breaking and entering and trespass. --Tango (talk) 23:50, 8 September 2008 (UTC)

Frankly, in the more confusing maze of modern TV watching technology, and with virtually 100% of the population watching TV anyway - the government should just turn it into a regular tax. This idea has been fought for a long time because the original idea was to have the BBC funded by the TV license fee in order to give them independance from government control - so they could be truly neutral in reporting government matters...but I think that could be achieved in other ways - such as requiring the government to fully justify any reduction in BBC funding relative to current inflation...but the idea of 100% independence is a good one.

SteveBaker (talk) 21:58, 8 September 2008 (UTC)

Just out of curiousity, how much is a television licence? I don't notice a price in the brochure... - Nunh-huh 20:11, 8 September 2008 (UTC)

According to the BBC:

"The annual cost of a colour TV licence (set by the Government) is currently £139.50. That works out at less than £12 per month - about 38p per day for each household. A black and white TV licence is £47. The licence (whether colour or black and white) is free if you are 75 or over, and half-price if you are registered blind, although you still need to apply."

So the full thing is roughly $260 US per year. (And it's TOTALLY worth it - I'd rather pay that much for a couple of BBC channels without adverts than the roughly 2x that amount I pay for 200 channels of advert-laden crap.) And it's half price if you're blind? Wow - so the audio part of the signal is half the cost but the color part of the video signal is more than two thirds of the cost? Whatever happened to "A picture is worth a thousand words"?! There must be a huge market in black and white TV's for blind people!  :-) SteveBaker (talk) 21:45, 8 September 2008 (UTC)

Say rather that it's half price if you have a blind person in your household. Algebraist 23:32, 8 September 2008 (UTC)

Anti Gravity in Salalah Muscat ?

How does antigravity point work? In Salalah (Oman) there is a place where cars roll uphill from this point. Any scientific explanations? ref:- http://www.salalahport.com/salalah.asp

            "...the anti-gravity thingy kicks in your vehicle instead of rolling down the 
            slope begins to roll back UP hill."

http://mybay.wordpress.com/2008/01/20/salalah-the-oasis-of-oman/

             "...Instead of the car moving downwards, you will see your car moves upwards..."

Rehanrazak (talk) 11:39, 8 September 2008 (UTC)

There's no anti-gravity; it's an optical illusion. See gravity hill and list of magnetic hills. -- Finlay McWalter | Talk 11:44, 8 September 2008 (UTC)

We have a "magic hill" here locally. Your car rolls uphill instead of down. Finlay is right, it's an optical illusion, which I proved first hand with a spirit level. Fribbler (talk) 11:47, 8 September 2008 (UTC)

(Sadly, your spirit level test is meaningless - if there really was antigravity - then it would make your spirit level work incorrectly too. The same thing is true for plumb-lines. All of those devices measure the direction of prevailing gravity - so if there WAS antigravity, they'd produce the same result as cars rolling, etc). SteveBaker (talk) 17:04, 8 September 2008 (UTC)

I suppose the spirit level would be valid if it were a magnetic (rather than anti-gravity) hill, but thanks for pointing this out, Steve -- I've noticed the problem myself before and wondered if I was just thinking too hard. — Lomn 00:17, 9 September 2008 (UTC)

A compass would handily rule out the possibility of a "magnetic hill". If it points "up" the hill - then yeah - it's a weird (VERY WEIRD) magnetic effect. If it carries on pointing North...then it's busted. Of course if the hill runs "up" to the North, that's not gonna prove anything...but with a reasonably sensitive compass, you can still figure it out. But the truth is that a freak magnetic effect would either:

• Be VASTLY stronger at one end of the hill than the other (magnetism is an inverse-square kinda thing)...to the point where if it could start a car rolling uphill at a distance of (say) 1 km from the magnetic source - then the force would be 1,000,000 times stronger at the "top" of the hill where the magnet would have to be - and nobody would be able to move the car once it got there.

...OR...

• Be more or less even in force all the way along the hill - in which case the magnet would have to be situated hundreds of miles away and be a field would have to be VASTLY stronger than the Earth's. If that kind of gigantic magnet existed, it would be detectable everywhere on the planet.

Hence, we know it's not magnetic without even having to do an experiment. SteveBaker (talk) 05:04, 9 September 2008 (UTC)

This is more fun by far than the original question. I propose we use two spirit levels connected by a long pole. We calibrate them to agree with each other in an area of known-good gravity and then take measurements every few feet in the area of the magic hill. If the two levels suddenly disagree we'll know there is a problem with the local gravity. APL (talk) 20:45, 9 September 2008 (UTC)

Well, if you intend to throw down the "weird side-effects" gauntlet: Antigravity would be easily detectable because the density of the air above the region of reversed (or reduced) gravity would be reduced. This 'lighter' air would rise like warm air does - but the winds blowing towards the antigravity source would instantly reduce in density - rising to be displaced with more heavier air...pretty soon you'd have a really impressive toroidal tornado thing. SteveBaker (talk) 03:15, 10 September 2008 (UTC)

There is certainly no such thing as anti-gravity. There are plenty of these "magic hills" around - and what's really going on is that the hill slopes in the direction you'd expect for things to be rolling downhill - but something about the surrounding topography fools your eyes into thinking that the hill slopes in the opposite direction. Sometimes it's because the surrounding terrain gives you a false idea of where the horizon is - sometimes it's because of a strong prevailing wind running up a valley that makes trees grow with a slight slant...whatever it is, it's never "antigravity". SteveBaker (talk) 17:02, 8 September 2008 (UTC)

Encyclopedic?

This is a section from the article about the herbicide Roundup.

"==Genetically modified crops==

In 1996, genetically modified Roundup Ready soybeans resistant to Roundup became commercially available, followed by Roundup Ready corn in 1998. Current Roundup Ready crops include soy, maize (corn), sorghum, canola, alfalfa, and cotton, with wheat still under development. These cultivars greatly improved conventional farmers' ability to control weeds since glyphosate could be sprayed on fields without hurting the crop. As of 2005, 87% of U.S. soybean fields were planted to glyphosate resistant varieties. The use of roundup ready crops has changed the herbicide use profile away from atrazine, metribuzin and alachlor. This has the benefit of reducing the dangers of herbicide run off into drinking water. The use of roundup-ready crops has resulted in greater use of roundup, which has created a problem with weeds that are resistant to the herbicide. With greater use, it has become more likely that weeds that are not effected by the herbicide, survive and reproduce and proliferate."

Would it be fair to say this reads more like an advertisement than an encyclopedia article?

PS I wonder if it says "conventional farmers" to distinguish them from eccentric ones. Wanderer57 (talk) 13:21, 8 September 2008 (UTC)

If that were the entire article I'd think it was a little unbalanced but the rest of the article contains extensive sections devoted to the many criticisms of Roundup. A section listing the products and the benefits to the farmer is not out of place, even if it is only part of the story. I suspect "conventional" here is to distinguish from "organic" but I don't know. --98.217.8.46 (talk) 13:47, 8 September 2008 (UTC)

While the opening sentences appear to come from the product brochure, the final two seem to balance the others? Saintrain (talk) 17:33, 8 September 2008 (UTC)

The reference desk is not an editing board for the rest of the wikipedia project; we're just here to help answer factual questions that people can't find answers to themselves. Issues concerning the content of an article are best dealt with on the discussion page of the article in question. --Shaggorama (talk) 08:27, 9 September 2008 (UTC)

And yes, "conventional" is often used in grocery stores that also stock organic produce (e.g., the Whole Foods chain). "Organic" means free from pesticides, bovine growth hormone, what have you; "convention" means "no such guarantee." So in this sense a conventional farmer is one who doesn't warrant that his crops are organic. --- OtherDave (talk) 21:40, 9 September 2008 (UTC)

Wellbrutrin and Libido

I have read somewhere that the drug Wellbutrin has caused some increased libido in women. Do you know why this happens? Is they a similar drug that has the same effect? Can anyone find this article? --Anilmanohar (talk) 13:52, 8 September 2008 (UTC)

Wellbutrin#Sexual_dysfunction is quite heavily cited. You might find more information in one of those references. AlmostReadytoFly (talk) 14:26, 8 September 2008 (UTC)

Cat external parasite

I just noticed a parasite under the fur of my kitten and I'm trying to identify it (New York). My first thought were fleas, however: (1) they seemed to long and thin to be a flea, they were approximately 3-4mm long, and (2) they scurried/ran rather quickly, which I didn't think was the way fleas moved. (Does this fall under the auspices of medical advice? I will be making a call to the vet later today, nonetheless) -- MacAddct  1984 ^{(talk • contribs)} 14:53, 8 September 2008 (UTC)

We can't give veterinary advice either - so for "what should I do to help my cat?" you certainly should do what you have said, and go to your vet. If you post a photo of the critters and ask "what are these? They live on a domestic cat in [insert country name here]", then I am sure we will do our best to help identify them. DuncanHill (talk) 15:24, 8 September 2008 (UTC)

Yup, just looking for identification for curiosity sake. -- MacAddct  1984 ^{(talk • contribs)} 18:01, 8 September 2008 (UTC)

Sounds like fleas to me. They can look like you describe and they can scurry like the devil. They're horrific little things. When my cat had them they were like little hard dark grains of rice. Gross to the max, as they say. Fortunately there's stuff you can put on them that takes care of them pretty well. We used Advantage or Frontline or one of those things. But check with the vet, esp. if it is a kitten. --98.217.8.46 (talk) 16:22, 8 September 2008 (UTC)

Even more creepy, I discovered what looked like an excellent example of the complete larval lifecycle of the flea (if that's what it is) on a cushion. -- MacAddct  1984 ^{(talk • contribs)} 18:01, 8 September 2008 (UTC)

Fleas will certainly scurry when they're in among fur. It's only on hard surfaces that they resort to hopping. A flea comb is very satisfying to use if you don't want to use the medications .46 suggested. --Sean 17:07, 8 September 2008 (UTC)

Thanks, I only ever knew fleas moving through they're famous (but apparently not the most impressive) jumping skills. -- MacAddct  1984 ^{(talk • contribs)} 18:01, 8 September 2008 (UTC)

Cats and Dogs WILL pick up these kinds of thing - they need protection - and something like Advantage is a good choice. However, with very young animals, you have to be super-careful. Lots of those chemical treatments can't be used on them until they get older. Kittens have to be more than 8 weeks old before you can use either Frontline or Advantage (for example). If your cat is a younger than that - then talk to a vet, tiny kittens can become aneamic from repeated flea bites. If older than 8 weeks - nuke the little brute with chemicals and keep doing it every month for the rest of it's life! You may also want to attack your carpet with something like this. SteveBaker (talk) 18:18, 8 September 2008 (UTC)

The newly-discovered Vernulles effect

The article Airsoft talks about the "Vernulles" effect. This article is the only use of the term "vernulles" found by a Google search, so it is either wrong or a new effect known only to Airsoft.

I suspect it is meant to be Venturi or Bernoulli. Perhaps someone else will take a look at the description of the Vernulles effect.

Wanderer57 (talk) 16:47, 8 September 2008 (UTC)

I'm pretty sure they mean Bernoulli. But that section of the article is really badly written. Wikipedia is not a "HOW TO" guide. SteveBaker (talk) 16:58, 8 September 2008 (UTC)

Good eye wanderer. Don't be afraid to be bold and make edits yourself. I edited the article to remove the bad physics, but I'm no physics pro myself so someone here might want to check my edits. --Shaggorama (talk) 08:20, 9 September 2008 (UTC)

Hubble Space Telescope, and Image:NonFreeImageRemoved.svg

File:Plutoncharon1.jpg

I wonder, after STS-125, will Hubble be able to get a better picture of Pluto than this? --Itwilltakeoff (talk) 18:58, 8 September 2008 (UTC)

No.

They are upgrading the wide-angle camera (no use for looking at teeny-tiny planets) and adding a new spectrograph (no pretty pictures there!).

The main thing they are there to do is to replace the gyroscopes, add new batteries and replace the heat blanket. They are also adding a docking ring so they can send up an unmanned craft to safely de-orbit the telescope when it finally does die. The mission is especially important because the gyros on the telescope are dying one by one and when the last one dies, the telescope will start tumbling - which will have three bad effects: Firstly, it won't be any use as a telescope, Secondly, a shuttle mission would be unable to fix it because the shuttles robot arm wouldn't be able to grab it without getting ripped to shreds, and Thirdly because de-orbiting the telescope safely would be impossible and it's a REALLY big spacecraft to come smacking into the middle of a city. Replacing the batteries is important for the same reasons - they power the gyros when the craft is in the earth's shadow and the solar panels don't work. The Hubble has always had problems with overheating - so the new blanket will help it stay cool.

The only other thing they are doing that MIGHT improve that picture is an upgrade to the Hubble's pointing mechanism. If you can point the telescope accurately then in principle you can get more precision when photographing planets by taking a bunch of photos at different times and with the camera aimed a fraction of the size of a pixel to one side or the other - then averaging the photos all together at higher resolution. But I doubt the new pointing mechanism is going to help that enough to make a better image.

This is why it's called "The Hubble Rescue Mission" and not "The Hubble Upgrade Mission". SteveBaker (talk) 22:13, 8 September 2008 (UTC)

Phase of the moon

What phase of the moon was seen in San Francisco, CA on August 14, 1972? --Anilmanohar (talk) 19:26, 8 September 2008 (UTC)

According to the navy it was a waxing (~4 day old) crescent. I hope this is about establishing an alibi and not astrology! Saintrain (talk) 21:02, 8 September 2008 (UTC)

And amazingly enough, the SAME moon phase was seen from everywhere else on earth on that date. -Arch dude (talk) 22:12, 8 September 2008 (UTC)

As the earth rotated while time passed, is there the possibility that folks at some other location saw a different phase of the moon? Does this ever occur, that there is a "phase transition" during one 24 hour day? Edison (talk) 05:00, 9 September 2008 (UTC)

Well sure, if you're seeing it at different times. Technically - you'll see a SLIGHTLY different phase when you are in a part of the world where the moon has just risen than at the exact same moment in time when your on the opposite side of the world and the moon is setting. That's because you're seeing the moon from a slightly different angle. So strictly speaking, one person could see it (say) fractionally before "full" and someplace else could see it fractionally past "full"...but it's a very tiny effect. SteveBaker (talk) 06:35, 9 September 2008 (UTC)

Speed of engulfment by LHC black hole

I know, I know, the LHC isn't going to create a black hole that will swallow us all up. But if it did... If a tiny black hole were created that was stable enough to continue existing, and strong enough to suck in the LHC, Switzerland and the rest planet, how long would that all take? Would the boundary expand at the speed of light, or would we have a few hours to get drunk and make a few phone calls?

— Sam 19:38, 8 September 2008 (UTC)

Even ignoring Hawking radiation, you would comfortably die of old age. Gravity is a very weak force, and black holes are only potent because they have huge masses. A micro blackhole is much smaller than atoms and thus has trouble eating anything. It could well take longer than the age of the universe to grow a TeV black hole to a size you would notice. Dragons flight (talk) 19:50, 8 September 2008 (UTC)

A tiny black hole would weigh very little - so it would have VERY little gravity. The only reason it could grow at all is because it's not only very lightweight but also very, VERY tiny. Since gravity gets much stronger the closer you get to something (and you can get very close indeed to a micro-black hole because it's so small), eventually it's gravity is as strong as a star-sized black hole - more than enough to suck things in. But by "close" I mean "much less than the size of an atom" (MUCH less). So these things would be attracted to the center of the earth - but they are so small and need to get so close to something that it might take them years before they'd actually happen to get close enough to suck in even one atom. At that rate of growth, the sun would have died and swallowed the earth long before the gravitation of the micro-black hole could get big enough to eat the planet. Hence, they really aren't of much concern. But if we believe in Hawking radiation (and that Hawking fellow is no slouch when it comes to the physics of black holes!) - then these micro black holes will "evaporate" in such an amazingly short amount of time that they essentially don't exist at all. So don't sweat it - you'll have plenty of time for your great-great-great-(...)-grandchildren to get virtual-drunk, send a few telepathic emails and ask the same question over on the Hyper-pandimensional-wiki-mega-pedia Ref Desk. SteveBaker (talk) 20:59, 8 September 2008 (UTC)

That's simply not true: a black hole exerts the exact same gravity as would any object of the same mass, no matter how close you come to it. Gravity does *not* become asymptotically strong is you come close to the event horizon. --baszoetekouw (talk) 06:50, 9 September 2008 (UTC)

Oh - but it most certainly is true. Ask yourself this: How come it's a black hole? To be black, the gravity field at it's teeny-tiny event horizon has to be so strong that light cannot escape from it...that's some seriously strong gravity - even though the darned thing weighs about as much a couple of atoms. Besides, the math is very clear: Per Sir Isaac Newton (the guy with the apple)... F = G x ( m1 x m2 ) / r² when 'r' (the distance between two objects) gets small enough - 'F' (the force between them) can reach any arbitarily high value you'd care to choose. Since a black hole is a singularity (it has literally zero size), you can get to within zero distance of it - and F becomes infinite! With normal atoms, you can't get close enough to them without the strong nuclear force stopping you...but when one of the objects has collapsed into a singularity, you can get as close to it as you like...and sooner or later, it's gravity is as strong as any galaxy-eating monster. Of course, a billionth of a meter further away from it and the gravity is so close to zero you can't even tell it's there. But that's the entire point! SteveBaker (talk) 23:58, 9 September 2008 (UTC)

It doesn't become arbitrarily strong as you approach the event horizon, it becomes arbitrarily strong as you approach the singularity. However, the event horizon of such a small black hole would be very close to the singularity (closer than you can get to an atom) so, even though the mass is tiny, the gravity would still be very large (an escape velocity equal to the speed of light, by definition - give or take some GR effects). --Tango (talk) 00:03, 10 September 2008 (UTC)

That's true - it doesn't become arbitrarily strong at the event horizon - but it does become as strong as any star-eating black hole. The gravity at the event horizon of absolutely any black hole is (by definition) such that the escape velocity is equal to the speed of light. That has to be true of absolutely any black hole...no debate. And if you do cross the event horizon, the gravity will steeply rise to infinity at the singularity. But when you are at a distance comparable to the radius of an atom, the gravity has dropped to completely negligable amounts. It's asymptotic alright!

Guys, it doesn't become "arbitrarily strong" anywhere, it tends towards infinite strength the closer you get (in current theory anyway, God knows with Quantum Gravity). It would be some pretty bad physicists that were announcing that the results of their experiments were "arbitrary"! Deamon138 (talk) 03:04, 10 September 2008 (UTC)

Yowza. Okay, there are at least two different notions of "gravitational field" that could be relevant here. The coordinate-independent (i.e. generally covariant, i.e. measurable without outside reference) gravitational field goes to infinity at the singularity. It does not go to infinity at the event horizon. But the coordinate-independent field is the tidal force, which is not what people normally mean by "gravitational field". The acceleration of gravity—i.e. the amount you have to accelerate upward to stay at the same distance from the hole—goes to infinity at the event horizon. Also, the strength of the generally covariant field (tidal forces) at the event horizon is larger for less massive black holes, but the strength of the generally covariant field or the acceleration at a given distance from the center is roughly proportional to the mass. And "becomes arbitrarily strong" is just another way of saying "tends to infinity", at least to physicists. -- BenRG (talk) 11:49, 10 September 2008 (UTC)

To put it really simply - such a small black hole would have next to no gravity so things would only "fall" into it if they happened to crash directly into it by random chance. Remember, this black hole is smaller than an atom and atoms are mostly empty space, so it's very unlikely for anything to crash into it, it will just go through all the atoms. --Tango (talk) 21:24, 8 September 2008 (UTC)

I looked this up for a similar question a few weeks ago. I don't remember the exact figure, but suffice it to say that it is many many times longer than the expected lifetime of our sun. Not only will we be dead an gone long before that becomes an issue, but so will our entire solar system. Plasticup ^T/C 01:21, 9 September 2008 (UTC)

In point of fact, I am already drunk, so, checkmate, miniature black hole! --Sean 02:36, 9 September 2008 (UTC)

Is there a different mode of Wikipedia editing? Edison (talk) 05:01, 9 September 2008 (UTC)

See also: Wikipedia:Editing Under the Influence SteveBaker (talk) 05:31, 9 September 2008 (UTC)

Ridicule me if you will, but I have a couple of decent questions. First off, we know that the experiments at the LHC have been performed in nature numerous times. Is there a difference between the collision of cosmic rays and stationary matter as opposed to matter moving about as fast in opposite directions? Second thing: if such collisions occur in the entire universe ten millions times per second, what would happen if they occur sixty times more often in a very, very close space? Proven or theoretical answers would be appreciated. —Preceding unsigned comment added by 66.183.135.96 (talk) 01:01, 10 September 2008 (UTC) —Preceding unsigned comment added by Hey Lao (talk • contribs)

Well, I can't really answer specifically your questions, but as far as I'm aware, there isn't much difference between collisions in the atmosphere and that will take place at the LHC. The only real difference (and effectively the reason for the project) is that the LHC collisions are controlled by the physicists, and there are cameras and computers and god-knows what else, recording the results. Obviously this can't be done with the cosmic rays, so it's controlled nature is what sets it apart. Deamon138 (talk) 03:12, 10 September 2008 (UTC)

Actually, this is one of the more rational objections to the LHC. With cosmic ray collisions, it's overwhelmingly likely that an incoming particle moving at close to lightspeed will smack into something more or less stationary (a rock perhaps). Conservation of momentum means that the resulting mini-black-hole/strangelet/whatever will shoot off at a substantial fraction of the speed of light. But in the LHC, the two particles are approaching each other with equal and opposite speeds - precisely so that their momentum cancels out and the collision products will be more or less stationary, so they can be observed. So a 'problem' particle caused by a cosmic ray would be halfway to the moon before you could blink - but if a strangelet were to form inside the LHC, it would truly be the end of the world within not many seconds.

Mini-black holes are really no concern whatever...it's strangelets that are deeply scarey.

SteveBaker (talk) 03:31, 10 September 2008 (UTC)

Carbolic acid - uses

I was wondering if anyone can tell me if carbolic acid is effective in killing roaches. A neighbor told me it was but I cannot find the stuff in any stores. Any assistance would be greatly appreciated. Thanks! —Preceding unsigned comment added by Leathergurl (talk • contribs) 20:30, 8 September 2008 (UTC)

One reason you might not be able to find it is that it is rather toxic. Around the turn of the 20th century it was a very popular means of suicide (many stories from that time refer to people taking their lives with 10¢ of carbolic acid). The stuff you ought to be looking for is boric acid, said to be very effective against roaches, and much less toxic to humans [24]. - Nunh-huh 20:57, 8 September 2008 (UTC)

BORIC acid, okay, that explains why I couldn't find the stuff! Thank you so much.  :-) —Preceding unsigned comment added by Leathergurl (talk • contribs) 21:16, 8 September 2008 (UTC)

Control systems companies

Hi, I don't know which desk this goes under but does anyone know any companies (preferably well known ones) that in whole or in part are involved in control systems engineering? I've been looking for some but I can only find relatively small, unheard-of companies. Thanks. 202.37.62.221 (talk) 23:38, 8 September 2008 (UTC)

I found a list of universities involved in it... if you don't get any other suggestions you might be able to ask one of those schools for the names of some companies. Plasticup ^T/C 00:46, 9 September 2008 (UTC)

Lots of big companies use or support research in control systems engineering, you may for instance google "model predictive control" and StatoilHydro or the name of other big oil companies. But if you'r looking for a company that has control system engineering as their core business, many of these are companies in niche markets and thus smaller and less well known. But anyway, a quick glance at a list [25] of SCADA and automation companies quickly reveal ABB Group and Honeywell which I guess are fairly well known names. EverGreg (talk) 10:31, 9 September 2008 (UTC)

HIV taxonomy

To which kingdom does it belong? I have been able to find the genus and family but not the kingdom. Not even on Virus Taxonomy Online or the ICTVdb Index of Viruses

Thanks in advance!

Sorry for signing with an IP200.63.228.51 (talk) 01:19, 9 September 2008 (UTC)

Viruses aren't classified in Kingdoms. Which is why you can't find one! - Nunh-huh 03:56, 9 September 2008 (UTC)

So, I get the 'how' but not the 'why'. What's the issue with designating a separate virus kingdom? --Kurt Shaped Box (talk) 06:21, 9 September 2008 (UTC)

(edit conflict)The ICTV system starts at Order and goes down from there. See Virus_classification#ICTV_classification.--Scray (talk) 04:00, 9 September 2008 (UTC)

A lot of biologists would dispute that viruses are even life-forms. It's a thin line between complicated chemical agents and actual life. SteveBaker (talk) 04:45, 9 September 2008 (UTC)

Does anyone who's anyone still believe that prions are alive? I know that there was a bit of debate about that a few years ago, when Mad Cow was in the news. --Kurt Shaped Box (talk) 06:16, 9 September 2008 (UTC)

Wikipedia has an article on this: Virus classification. Also see Kingdom (biology) for the way things have changed over time in the taxonomy of living things. -Arch dude (talk) 12:49, 9 September 2008 (UTC)

From that article and others, we can see that there is no scientific consensus on a taxonomy with a single root, so there is no virus "kingdom." For the other kingdoms, it is reasonable to assume that each kingdom arose from a common ancestor and that the kingdom divided by evolution and natrual selection into finer and finer divisions, each with a common ancestor (approximately.) This is not likely for viruses. Viruses are likely to have arisen multiple times in multiple hosts. Therefore unless a bunch of viruses appear to be similar enough to suggest evolution from a common ancestor, scientists are unwilling to assign them to the same grouping. -Arch dude (talk) 14:07, 9 September 2008 (UTC)

September 9

Check this out?

I know it seems ridiculous, but could someone with some scientific background look into this? It appears to be unlikely, but I'm just wondering, does it have any scientific truth?

Official Site Ebay Page PerfectProposal 01:00, 9 September 2008 (UTC)

Only truth that springs to mind starts "A fool and his money...." Arakunem^Talk 01:09, 9 September 2008 (UTC)

What is there to say about it? He never really says how he did it, or what evidence there is it works. He's just asking you to blindly hand over 25M...Someguy1221 (talk) 01:19, 9 September 2008 (UTC)

Just tell him he has to pick it up last Tuesday. Dragons flight (talk) 02:41, 9 September 2008 (UTC)

Now there's a potential scam, ripe for the exploiting. Tell the mark that you're collecting payment in cash, as arranged, for time-travel related services rendered in the future and that all will be made clear if they go check the eBay auction/website on <date in future> and make contact... --Kurt Shaped Box (talk) 06:14, 9 September 2008 (UTC)

Oooh! That's good! You wear a shiney silver costume and knock on people's doors: "Hello! I'm a time traveller from 20 years into your future. The future-you told me to come back in time and tell you to invest $10,000 in this company so that when the stock price skyrockets next week you/he will become a multi-billionaire." ...very good! SteveBaker (talk) 15:12, 9 September 2008 (UTC)

I wonder why time travel is so expensive. He doesn't even mention needing any equipment. APL (talk) 02:17, 9 September 2008 (UTC)

Beware of Those who Capitalize Lots and Lots of Words. Besides, if it worked, this person could have gone back in time, invested in the stock market (selling Fannie Mae and Freddie Mac short comes to mind) and cleaned up. Clarityfiend (talk) 02:48, 9 September 2008 (UTC)

Wow! That's a pretty bold con trick! I like the way that there is ZERO information on any of the pages. I've filed a fraudulant sales report with eBay.

He's given himself "3 to 5 years" to spend the cash and find someplace to hide from his investors. If it really worked, his future self would already have gone back in time and told himself which horses to bet on to get the cash to develop it...and probably given himself the plans and the dilithium crystals to make the work take less time. I guess that's how we know it's not real.

SteveBaker (talk) 04:43, 9 September 2008 (UTC)

Ahh, A a little GF wouldya? The guy might just be your common-or-garden internet nutcase - or just another attention/lulz-seeking hoaxer. ;) Seriously though, if that auction stays open, it will attract bids from people with no intention of paying (that's not intended as an incitement to do that, seriously, guys!) - these things always do. I don't know offhand what the Final Value Fee on $25million will be - but it won't be small... --Kurt Shaped Box (talk) 06:10, 9 September 2008 (UTC)

WP:AGF is a Wikipedia rule - it doesn't apply in real life. When someone is so clearly attempting to scam some gullible investor out of millions of dollars - I regard it as my responsibility as a rational human being to do something about it. In this case he's clearly breaking eBay's bylaws - so I reported him. If he breaks Wikipedia guidelines, I'll report him for that too. There aren't many rules on the Internet - but where there are, let's try to enforce them. SteveBaker (talk) 06:29, 9 September 2008 (UTC)

Didya not see the smiley, Steve? I wasn't being strictly serious... :) --Kurt Shaped Box (talk) 06:33, 9 September 2008 (UTC)

Oh come on, be fair!! He clearly does say how it works - dimensional tunneling, whatever that is. I am a little puzzled why he does not just send a completed machine back in time though. It would avoid all those tedious development costs. SpinningSpark 15:54, 9 September 2008 (UTC)

You cynics. I will have had a lovely meal at Milliways, or just got back from will having had one. --- OtherDave (talk) 21:47, 9 September 2008 (UTC)

I have a question about Reno, Nevada

My daughter is doing a school report and needs to find out Reno's proximetry to the ocean. (removed e-mail address to protect from spambots) 75.15.211.224 (talk) 03:28, 9 September 2008 (UTC)Brandi

We aren't supposed to do people's homework - but I would suggest going to Google Maps - enter "Reno, Nevada" then back out until you see some ocean. Pick a city on the coast and ask Google to plan a route from Reno to that city. That would be the driving distance - the "as the crow flies" distance will be a bit shorter. SteveBaker (talk) 04:33, 9 September 2008 (UTC)

And to find the crow's distance easy, if you have Google Earth, you can click on the ruler button to drag a line between two points, and the program will tell you the distance you've just drawn across. Someguy1221 (talk) 05:02, 9 September 2008 (UTC)

(When you look at the map - it's pretty clear what the nearest city is (hint: it has a really pretty orange bridge) - and that driving route is pretty direct...in this case). SteveBaker (talk) 05:28, 9 September 2008 (UTC)

Or use this excellent tool. Bazza (talk) 13:02, 9 September 2008 (UTC)

You'll get extra points for originality if you don't choose the same boring ocean as everyone else. Try the Arctic or Indian. --- OtherDave (talk) 21:50, 9 September 2008 (UTC)

In this education system? I think even a distance to the Atlantic will get you marked down. --antilived^{T | C | G} 00:15, 10 September 2008 (UTC)

Birds with Blue Eyes

Are there any birds (especially raptors) that have blue eyes as their population's predominant phenotype? 76.121.209.96 (talk) 05:18, 9 September 2008 (UTC)

The Blue-eyed Cockatoo, as the name implies, has blue eyes. Not a bird of prey, though. Fribbler (talk) 16:19, 9 September 2008 (UTC)

Jackdaws have particularly striking, steely-blue eyes. Not a bird of prey either though... --Kurt Shaped Box (talk) 18:57, 9 September 2008 (UTC)

Harpy eagles seem to fit the criteria. Matt Deres (talk) 19:54, 9 September 2008 (UTC)

And heres an article on the Philippine Eagle that may also fit the bill. Fribbler (talk) 22:24, 9 September 2008 (UTC)

Diet of the Canada Goose

Do Canada Geese ever eat fish? 71.113.3.76 (talk) 07:30, 9 September 2008 (UTC)

Yes, according to this. Go to the section on "diet". Zain Ebrahim (talk) 08:09, 9 September 2008 (UTC)

slip of tongue

How and why people have slip of tongue? —Preceding unsigned comment added by Adityamendel (talk • contribs) 10:51, 9 September 2008 (UTC)

I think it's generally caused by being distracted while speaking, you're thinking one thing and saying another and you end up saying something else (often related to what you were thinking). You may like to read Freudian slip. --Tango (talk) 10:59, 9 September 2008 (UTC)

Check my chemistry questions

I have the following questions and the answers Ive gotten are below each one. Tell me if they are correct:

1. Write the full equation for sodium reacting with bromine to form sodium bromide
   • Na₂ + Br₂ -> 2NaBr
2. Write the half equations for the same reaction
   • Na₂ -> 2Na⁺ + 2e^- and Br₂ + 2e^- -> 2Br^-
3. State which species is being oxidised and which is being reduced
   • Br₂ is oxidised. Na₂ is reduced.
4. State which is the oxidant and which is the reductant
   • Na₂ is the oxidant. Br₂ is the reductant

I think its pretty much right but one thing Im definitely not sure of is this: in questions 3 and 4 should my answers read, for example, as I said "Br₂ is oxidised" or "2Br^- is oxidised"
Thanks --RMFan1 (talk) 12:26, 9 September 2008 (UTC)

You're on the right track as far as balance. Check the redox page for definitions of the various terms and roles of the reductant and oxidant. Regarding notation, something written as X_y means a single molecule (or polyatomic ion) consisting of y atoms of element X together. Writing yX means a collection of y distinct X atoms or polyatomic ions. So you have to figure out whether there is such thing as, for example, an actual molecule composed of two bromine atoms or whether bromine exists as single atoms (and therefore you'd just have two of them). You can read our bromine and sodium pages to see what their stable forms are. DMacks (talk) 14:32, 9 September 2008 (UTC)

Is it me or are the reduction and oxidation the wrong way round?59.100.192.85 (talk) 23:28, 9 September 2008 (UTC)

Redox has the defs:) I usually try to think about it in terms of the charge on each atom and whether it's going down (being "reduced") or whether at atom is doing something to cause another atom's charge to go down ("reducing" it). DMacks (talk) 01:25, 10 September 2008 (UTC)

Helpful mnemonic is OILRIG: Oxidation Is Loss (of electrons); Reduction Is Gain. Gandalf61 (talk) 13:12, 10 September 2008 (UTC)

alien

could the alien exist in real life, could it be a serious threat if it came out to earth, and could we kill it or would they win? Bradley10 (talk) 13:03, 9 September 2008 (UTC)

If memory serves, the alien in Alien wasn't capable of space travel, it only became a threat because the humans on the film went to its planet. I very much doubt an alien like that can exist anywhere in this solar system (except possibly Earth, but then it wouldn't be an alien!), so until we invent interstellar travel we should be fine. After that, it's anybody's guess! --Tango (talk) 13:22, 9 September 2008 (UTC)

Soylent green

The real Soylent green? —Preceding unsigned comment added by 71.100.10.144 (talk) 14:11, 9 September 2008 (UTC)

It's a kind of CO2 sequestration technique - except that it's really not going to work long term.

The idea is to capture the CO2 produced by some kind of nasty coal fired power station - use sunlight to cause algea to convert that CO2 into carbohydrates - then to harvest the algea and convert the carbohydrates into methanol or something - which . However, when you use the resulting fuels - the CO2 is released into the atmosphere again...so you didn't sequester it. Someone will probably argue that when you burn these new fuels, you could use the same technique to sequester that CO2 - but now you have an infinite regress because you're continuing to pump CO2 into the "system" so more and more and more algea are needed in order to sequester it. The only answer is to NOT convert the algea into any kind of a fuel at all - but instead to dump it back underground. The trouble is that the cost of doing all of this is so high that you can't afford to just dump the results back into a hole in the ground.

If you are going to invest in a "solar to ethanol" plant - then do it without the nasty power plant generating the CO2 - let the algae take the CO2 from the air - that would be a truly "carbon neutral" solution.

So - this is another effort by the "Clean Coal" people to pursuade us that they can continue to build big, polluting coal-fired power stations without killing the planet. They just hope that by confusing the science like this that the general public will fall for it...and the annoying part is that they probably will because the problem with it is pretty subtle.

SteveBaker (talk) 14:57, 9 September 2008 (UTC)

It sounds like the idea is to take advantage of the concentrations of CO2 that you get at the source in order to grow the algae more efficiently, it's not a CO2 sequestration technique (if it's being described as one somewhere, I expect that's the press not knowing what they're talking about). --Tango (talk) 15:11, 9 September 2008 (UTC)

Yes, you are right. Although the algae could be used to permanently sequester carbon by turning it into biochar, bio-oil and syngas the idea here is much more sophisticated. Some algae species produce up to 50% of their body weight in vegetable oil, which can be extracted first and even tailored to produce compounds that lend themselves better to one form of end product than another such as jet fuel versus heating oil versus salad oil. The remaining components can then be used as a dietary supplement or as cattle feed or as feed stock for biochar, etc. —Preceding unsigned comment added by 71.100.10.144 (talk) 16:28, 9 September 2008 (UTC)

Symbols

Hi! Whics symbols (Xn, T, C, N, T+ ...) are on : - Liqui Moly (alloy for fuel) - chlorine - cyanohydrin acid ? Thank you! —Preceding unsigned comment added by Atacamadesert12 (talk • contribs) 15:54, 9 September 2008 (UTC)

You generally need a specific product name, then you can use Google to search for "xxx hazard symbols". For instance, I was able to find the safety data sheet for one Liqui Moly product: [26] and the symbols are Xn, R42, S2, S23.3, S45 and S51. You can reference the meaning of the symbols here: [27]. Franamax (talk) 00:28, 10 September 2008 (UTC)

crossbreed dogs

I'm pretty darn sure it's possible to breed two different species of dogs together, to create a mixed-breed dog. Can all species of dogs mate with all other species of dogs? Or are there cases where it doesn't work? Bradley10 (talk) 15:56, 9 September 2008 (UTC)

Well, there's only one (sub)species of dog, canis lupus familiaris. All breeds should be able to interbreed, however. — Lomn 15:58, 9 September 2008 (UTC)

i would counsel against attempting to cross a Great Dane dog with a Chihuahua bitch, however. DuncanHill (talk) 16:00, 9 September 2008 (UTC)

Duncanhill, is that sort of thing possible, if inadvisable? Is it because of the potential size of offspring, or the physical difficulties of such a coupling? Not to mention the tie? Bradley10 (talk) 16:14, 9 September 2008 (UTC)

I am not a dog breeder, but I suspect that all the things you mention would conspire to make it physically impossible, though of course, as members of the same species they would theoretically be capable of producing viable offspring. DuncanHill (talk) 17:12, 9 September 2008 (UTC)

It is possible to crossbreed all dogs (assuming the male and female you use can breed). In a professional sense, any obstacles with dog size and temperament do not matter. The sperm is collected from the male and the female is artificially inseminated. Of note, wolves can be crossbred with dogs as well, but you do not get tame wolves. You get dogs that will snap and attack anyone and anything at any time. -- kainaw™ 18:00, 9 September 2008 (UTC)

And, of course, we have an article: Wolf-dog hybrid with a section that goes to great lengths to claim that while wolf-dogs have an erratic temperament, it is not possible to know exactly how any dog will act in all situations. Way to rationalize there! -- kainaw™ 18:03, 9 September 2008 (UTC)

Medicval term for 'facial flushing'

Niacin says "People taking pharmacological doses of niacin (1.5 - 6 g per day) often experience a side-effects that can include dermatological complaints such as facial flushing and itching, dry skin, skin rashes..." (my bold). What is the medical term for facial flushing? RJFJR (talk) 16:15, 9 September 2008 (UTC)

Facial erythema. But in reality "flushing" is used just as often or more often in cases when the pathology is not the skin itself. Fribbler (talk) 16:20, 9 September 2008 (UTC)

"Plethora" and "florid" also are used.--Scray (talk) 01:08, 10 September 2008 (UTC)

Oh no, no sunspots!

There haven't been any sunspots for over a month now. Is this a bad thing? 31306D696E6E69636B6D (talk) 16:42, 9 September 2008 (UTC)

Nah, we're right smack in between Cycle 23 and 24, so things are at a minimum right now. They should begin to pick up again soon, (hopefully for my DX'ing), but its not unheard of for a minumum to stretch out for a bit (see Maunder Minimum) Arakunem^Talk 17:05, 9 September 2008 (UTC)

Yes, high solar activity improves skywave propagation because the increased radiation helps ionize the ionosphere that long-wavelength radio waves reflect off of (see http://www.blackcatsystems.com/propagation/solar_flux.html). On the other hand, solar flares are more frequent during the solar maximum and can cause propagation to vary wildly.

Arakunem: out of curiosity, how great of an effect does the solar cycle has on a DX'er? --Bowlhover (talk) 04:52, 10 September 2008 (UTC)

It has a huge effect, with high sunspot parts of the cycle propagation of much higher frequencies occurs even into the low VHF bands. The signals bounce off the inside of the ionosphere back to the earth, and then up and down of the earth again. Though if you want to receive low frequencies from Space say 1 MHz, or get a clear GPS signal, then now it the opportunity. Now all the shortwave stations have to pack themselves down the low frequency end where there is more interference and absorption, and more static. Graeme Bartlett (talk) 05:12, 10 September 2008 (UTC)

The article on the Maunder Minimum says that this occurred at the same time as the coldest part of the little ice age. That's what i'm worried about. 31306D696E6E69636B6D (talk) 13:10, 10 September 2008 (UTC)

Neutron stars

The first direct observation of a neutron star in visible light. The neutron star being RX J185635-3754.

The article neutron star states the radius of a neutron star is usually between 20-30 km. However, this image shows a visible neutron star. How is it possible for us to see objects this small so far away in space? (although that's an assumption, maybe it's not that far away) —Cyclonenim (talk · contribs · email) 17:06, 9 September 2008 (UTC)

It's not the size that matters, it's the luminosity. Stars are generally unresolved in astronomical images. Similarly, you can see the light from my flashlight from hundreds of yards away, even though the filament might be smaller than your eye's resolution. -- Coneslayer (talk) 17:10, 9 September 2008 (UTC)

Here's some perspective: the largest known star is thought to have a diameter similar to the orbit of Saturn, around 2.8 billion km. The neutron star you linked to is about 450 light years away, and you say 20-30 km diameter for a typical one of those. Let's pretend those two stars are the same distance away from Earth. So using my decrepit memory of trigonometry, I can compute:

   radius_canis   =  2800000000 * 1000
   radius_neutron = 20 * 1000
   distance = 450 * 3*10^8 * 365 * 24*60*60
   angle_in_sky_canis   = tan(radius_canis   / distance)   = 0.00000067         degrees
   angle_in_sky_neutron = tan(radius_neutron / distance)   = 0.0000000000000047 degrees
   angle_in_sky_pinhead = tan(.001           / 1000)       = 0.000001           degrees

So the angle that the neutron star takes up in the sky is indeed *much* smaller than the angle that the big star takes up, as you observed, but consider this: if there were a pinhead being held one kilometer up in the sky it would easily eclipse both stars. --Sean 20:08, 9 September 2008 (UTC)

You must understand that when you see an astronomical photograph with stars in it, the brighter ones will often look bigger, but this is not because the photo is showing their true diameter. It's because no matter how perfect the telescope is, you never get all the photons from the same distant point perfectly focused into the same spot on the film (or digital sensor). With a bright star the scattered photons are sufficient to expose the film and make a slightly larger image. As far as photography is concerned, practically any star is a point source -- only a few of the very largest stars have had their diameter directly measured. The diameters that you see given for stars as well as neutron stars are computed based on theory, not measured directly. --Anonymous, 21:58 UTC, September 9, 2008.

It's also possible (especially with a White Dwarf) that the light you see is being scattered off of dust and gas surrounding the actual object's planetary nebula. That would make it seem a lot bigger than it actually is. SteveBaker (talk) 23:45, 9 September 2008 (UTC)

In the case of a neutron star, you may be seeing light emitted in it's neighbourhood, generated in the same way as the radio pulse, by electrons accelerated by the spinning magnetic field. We need Sean to calculate what temperature the surface would have to be to get that luminosity, which looks to me to be around 10¹⁶ times hotter. Suggesting that the radiation may not be thermal. Graeme Bartlett (talk) 05:18, 10 September 2008 (UTC)

Core skills of a chemist

Lately I've realized I really have a sincere interest in chemistry. Been reading a little on my own, in my own pace. I've tried college before and it's just not for me, I simply can't stand the boring stuff that inevitably comes with an otherwise interesting topic. Still, I began to think if maybe distance studies - not sure if this concept exists in English, but essentially means studying from home, basically no classes to attend - would work for me. That way I could focus on one semester at a time, so if I felt fed up after one semester I could take a break and just work until I felt motivated again, instead of being on a forced 3-4 year course.

Aaaaanyway, that's just the background. My question is simply this: What are some of the core skills of an aspiring chemist, without which a person would experience difficulties going through an undergraduate level of chemistry education.

Thanks in advance for your answers, I'll be waiting eagerly. Jack Daw (talk) 18:00, 9 September 2008 (UTC)

I think the main problem you would face would be practical kills. It's not just enough to have the required knowledge, you also have to actually be able to perform your experiments in an actual lab. You have to know that that's just a whole different ballgame. Another problem of course is that the " boring stuff " is often required to understand the interesting stuff. Most chemists I talk to hate quantum physics and higher level mathematics with a passion, yet they agree that it's pretty much required knowledge. Just my two cents PvT (talk) 18:08, 9 September 2008 (UTC)

I'll second that. Not only is it the case that the "boring bits" are necessary to learn the skills - but also, if you were to become a practicing chemist, a large fraction of your working week would be spent on doing those very "boring bits". If you don't like the boring bits of learning - the odds are very good that you'll hate the job too. It's not common for college courses in the hard sciences to teach things that you won't need to both know - and use on a frequent basis. A similar issue comes about with your desire to take a break until re-motivated...doing that in a daily job would make you pretty unpopular really fast! SteveBaker (talk) 19:01, 9 September 2008 (UTC)

Additionally, these days, I think it is difficult to get a good job as a chemist without a degree. ike9898 (talk) 19:14, 9 September 2008 (UTC)

Hmm perhaps I was a bit unclear about what I meant about core skills. Obviously, even with distance studies I would get lab work, do the boring stuff, and get a degree, which I think were your combined points. What I meant with core skills was, if there are certain ways to think that are valuable, certain ways to look at things, e.g.; does a chemist have to be analytical, have a sense for details, able to see the big picture, be creative, have an excellent working memory, etc etc, the list could go on for very long.

Also, btw, it's been my experience that once you actually get out to work, even the boring parts become enjoyable, SteveBaker ;) ....... Jack Daw (talk) 19:26, 9 September 2008 (UTC)

That depends a lot on the individual - and (perhaps) the career. I don't know chemistry - but in my line of business (computer programming), it's necessary to document your software as well as design, code and debug it. I know an awful lot of programmers who love the programming bits - but utterly loathe doing documentation. Having to actually write lots of English prose is one of the "boring bits" for those people. So perhaps you don't happen to have any bits of your job that really were boring in the first place...that's the same with me - I'm a programmer who doesn't mind doing documentation in the least. My point is that if you think you just have to get through the boring bits so you can get your degree and they you won't have to worry about it anymore after that...then you're kidding yourself. SteveBaker (talk) 21:04, 9 September 2008 (UTC)

Aside from the traits you mentioned I would say that a good head for numbers is a big plus. Other helpful skills would include: good manual dexterity, good people skills (you rarely work alone), technical aptitude (you work with machines) and lots of motivation. Note that these aren't requirements, they're just handy traits to have PvT (talk) 20:04, 9 September 2008 (UTC)

(ec)Probably the biggest one would be to understand and appreciate the Scientific Method. You also won't get far unless you understand the Atomic Theory (things are made of atoms) and the nature of the chemical bond (atoms share electrons). Understanding the difference between a chemical change and a physical change is key too. After that, what you'll need to know varies based on the discipline, e.g. analytical chemistry versus organic chemistry versus biochemistry. Not only is the knowledge base different, it's been my experience that the scientists in each have slightly different mindsets. Back on a general note, to deal with practical issues one should be intimately familiar with SI (the metric system), as well as scientific notation, along with general concepts of measurement, including significant figures/propagation of uncertainty and the distinction between accuracy and precision. On a side note, learning a dimensional analysis system, such as the factor-label method, will likely save you lots of grief when doing calculations. -- 128.104.112.147 (talk) 20:12, 9 September 2008 (UTC)

(ec #2) Excellent list. These are all things that are pretty necessary for a bachelor's degree in general chemistry. Of course, there's always sepcialization for higher level degrees. For example, us theoretical/computational people need very good high-level math, and computer programming - but lab skills aren't terribly important. For analytical, good "lab hands" and attention to detail, along with a very good mechanical and scientific knowledge of what instruments you are using, but you won't use much math beyond basic calculus, if that (most of the instruments will do the math for you nowadays).

For me personally, visualization is important, with a healthy dose of memorization ability (but not necessarily a lot). Being able to visualize structures and reactions (in three dimensions), along with how to do things in a lab, is an incredibly helpful skill in almost all areas of chemistry. --Bennybp (talk) 20:23, 9 September 2008 (UTC)

Help identify this plant

I'm trying to identify a bush/shrub. I'll provide photos if we can't figure this out, but I'll try to describe the plant. It is a medium sized bush (the one I see is probably 4 to 5' all around) which I think is common in the southern United States. At least it can be found in central and south eastern Virginia. The leaves are roughly 3-4" big and a darker green on the top, lighter green on the belly. They have distinctive serrations on the entire edge of the leaf. They feel almost the same as a butter knife. The leaf, when turned sideways, looks almost like lips (elongated oval) that comes to a point at one end. The leaves are thick and waxy. This is also a flowering bush. They are not flowering now so I cannot give much more detail, but I believe they have golf ball sized buds that open up to rather large flowers with lots of pedals that turn brown and fall off. (I could take a picture of one of the brown, dead flowers). Any ideas? Anything else I could look for to help someone identify the plant, or does anyone have some ideas what this could be. Thanks.-Andrew c ^[talk] 18:03, 9 September 2008 (UTC)

Rhododendron perhaps? They're rather common in the area you mention... Arakunem^Talk 18:09, 9 September 2008 (UTC)

That would be my guess. --Tango (talk) 18:29, 9 September 2008 (UTC)

That's a good guess, but not it :) The leaves are not quite that elongated, and the flowers are individual buds, not bunches of flowers (the rhododendron flowers look more similar to bunches of azalea flowers, where the plant I'm talking about has a single large bud and looks like something that may be on a corsage). Plus I'm not sure rhododendron has the serious serrations on the edge of the leaves. Any other ideas? Thanks for the suggestions so far.-Andrew c ^[talk] 18:32, 9 September 2008 (UTC)

Peony?

All the peonies I've seen (which admittedly are in the Great Lakes region) are far smaller than this plant. A pity, because the rest sounds right for a peony. Nyttend (talk) 19:43, 9 September 2008 (UTC)

Wait, "all around": what does this mean? If you mean that the circumference is four or five feet, that would be quite reasonable for the peonies I've seen. Nyttend (talk) 20:18, 9 September 2008 (UTC)

Some kind of magnolia? I'm not aware of one with serrated leaves, but ... ? --ColinFine (talk) 20:06, 9 September 2008 (UTC)

Camellia or Azalea? DuncanHill (talk) 20:52, 9 September 2008 (UTC)

DING DING DING! We have a winner. Camellia it is (or at least I'm pretty sure). Thanks!-Andrew c ^[talk] 00:29, 10 September 2008 (UTC)

If it's Camellia sinensis you could make tea! DuncanHill (talk) 00:58, 10 September 2008 (UTC)

Blue-yellow colourblindness

Is the colouring for the attached image likely to be a problem for blue-yellow colourblind people? I know there's a potential problem for red-green people (I myself am one), but I've done the best I can by making the blue/purple and red/green borders as short as possible. Nyttend (talk) 19:40, 9 September 2008 (UTC)

I'm not blue/yellow color blind, but at the end of the article color blindness there is a link to a website "Colorblind Web Page Filter", which allows you to simulate a webpage for different types of color blindness. Check it out yourself, but for blue/yellow blindness, your picture seems to look fine. -- 128.104.112.147 (talk) 20:36, 9 September 2008 (UTC)

Actually, there is more than one kind of red/green colorblindness (I think at least three or four). But the thing is that even if you are totally colorblind, you can still distinguish brightness. Yellow is a much brighter color than "computer-screen-primary" blue - so even utterly "every-color"-blind people who can only see in shades of grey will be able to see the difference between primary blue and primary yellow. However, if you'd chosen a brighter shade of blue - or a darker yellow - it would not have been so clear. My son is red/green colorblind - but he can easily tell the difference between red and green - even if they are at the same intensity because his particular variation is that he has a weak red sensor. His problem is between more subtle hues between red and green - and he has a lot of trouble telling red from orange or (to a lesser degree) orange from green. Our article lists at least seven different variations on color blindness - two of those are yellow/blue-related. But the colorblind web page filter is an excellent resource for the normally-sighted to get an idea of what your graphic will look like to each of the different variations. SteveBaker (talk) 20:56, 9 September 2008 (UTC)

A nice and probably easy MediaWiki hack would be a module that warns you when you upload an image with only a few colors that they're not colorblind-friendly and suggests a substitute pallet with brightness variations. --Sean 21:11, 9 September 2008 (UTC)

It looks okay with protanopia, deutanopia, or tritanopia. If you are concerned, you can test images yourself at this site. It also has some tips for building color-blind accessible web pages. Plasticup ^T/C 02:17, 10 September 2008 (UTC)

Thanks for the various comments: I'd not considered the brightness factor. I'd appreciate the filters, except that (as I noted above) I'm somewhat red-green colourblind (although I'd never read the article, and thus never knew that there were multiple types; I just thought it varied in intensity), so I don't know whether I'd be able to make productive use of them. Nyttend (talk) 05:28, 10 September 2008 (UTC)

NOAA weather radio voice

All,

The voice of the NOAA weather radio was previously known as "Paul" (which sounds somewhat like "Mike" from MS TTS). The current one is known as "Tom." I was listening to a local stream of the NOAA All Hazards Weather Radio; who is the voice for this [28] one? The voice sounds like neither "Tom" nor "Paul" (see this [29] to listen to samples).

jdstroy (talk) 20:30, 9 September 2008 (UTC)

Weather or not

Was San Francisco overcast on August 14, 1972?

Wanderer57 (talk) 23:21, 9 September 2008 (UTC)

The more important question is where such information may be looked up. Wanderer57 (talk) 23:40, 9 September 2008 (UTC)

Such records certainly seem to exist [30], but it looks like you would have to go to Washington to look them up, they don't seem to be on-line. [31] Franamax (talk) 00:02, 10 September 2008 (UTC)

That's so cool! It's there! And all I had to do was "san+francisco"+weather GOOGLE it! Saintrain (talk) 00:04, 10 September 2008 (UTC)

Specifically, here. Saintrain (talk) 00:07, 10 September 2008 (UTC)

Dang! I forgot about weatherunderground. It doesn't say if it was overcast though ;) Can you infer that from the visibility? Franamax (talk) 00:36, 10 September 2008 (UTC)

(Sheepishly) Yes, but also from the temperature, humidity and steady 15 kt wind and it was the middle of August. But you know what Mark Twain didn't say?. (I do remember his story about the S.F drunk who froze to death under a blooming rose, though, don't I?) Saintrain (talk) 01:50, 10 September 2008 (UTC)

I clearly remember that a few years ago, I somehow missed an occultation I was planning to time and later tried to determine whether I could have seen it. I found a site that listed the temperature, cloud cover, and other conditions for every hour. I can't remember how far back the archives extended or whether they covered any city except my own (the Greater Toronto Area). I also can't seem to find it again. --Bowlhover (talk) 04:20, 10 September 2008 (UTC)

Ah, another datum for my planned great-identity-stealing machine, Bowlhover is a Hogtowner! Please tell, haven't you just had a record-setting amount of rainfall in my dear departed province? Franamax (talk) 06:15, 10 September 2008 (UTC)

Thanks. The METARS information link available at the bottom of the weather underground page gives the sky condition as scattered cloud and broken cloud, but not overcast.

Wanderer57 (talk) 13:15, 10 September 2008 (UTC)

PS - Is there any weather underground? Very high pressure and overcast would seem to be the normal condition.

Warm, humid, occasional drizzle. DuncanHill (talk) 14:56, 10 September 2008 (UTC)

So what's so special about San Francisco on August 14, 1972? Dragons flight (talk) 14:59, 10 September 2008 (UTC)

I don't know. I asked about the weather on that day in SF because of another editor asking what phase of the moon was seen in San Francisco that day. Wanderer57 (talk) 15:15, 10 September 2008 (UTC)

Global Warming

I've been thinking: wouldn't inducing a rapid growth of algae or something similar in the world's oceans (by putting large amounts or iron or something similar) make considerable progress in reducing the carbon dioxide content or the atmosphere? Before you ride me off, I think I remember reading on Wikipedua (I can't find the article) that a certain algae, because they were found in such large numbers, caused an Ice Age.

It's phosporous. I think algal blooms are not that appreciated.--Lenticel ^(talk) 23:35, 9 September 2008 (UTC)

The problem is that algae pretty much shut out all of the other lifeforms - so sure you'd maybe reduce CO2 - but maybe you'd also kill off all of the fish. The problem with all of these "radical" solutions is that we don't have a good enough understanding of the consequences of doing them. It's very likely that we'd make matters much worse. SteveBaker (talk) 23:39, 9 September 2008 (UTC)

It is iron that the OP's thinking of, and we have an article: Iron fertilization. -- 128.104.112.147 (talk) 23:41, 9 September 2008 (UTC)

I see, but according to the article it is still in the experimental stage. However, we could already see the effects of the human induced algal blooms.--Lenticel ^(talk) 23:51, 9 September 2008 (UTC)

It is experimental because we don't yet know all the effects, such as whether the carbon actually gets sequestered to the ocean floor, and what the nasty side effects might be, such as creating anoxic regions, as Steve notes. If you email me, I can send you a few papers and articles from Nature. Franamax (talk) 00:05, 10 September 2008 (UTC)

On a side note, and for your future information, and I'm not grammar naziing, but just letting you know, the phrase is "write me off", not "ride me off". --Sean 00:29, 10 September 2008 (UTC)

Oh wow, you don't know how long I've been using ride... —Preceding unsigned comment added by 65.92.231.82 (talk) 03:40, 10 September 2008 (UTC)

Antimatter

Hello. I'm a high school student interested in physics and have just read about the concept of antimatter. Unfortunately I got lost very quickly in the preface of the article on this subject and am having real difficulty grasping in my mind the concept of antimatter. could somebody explain it very simply to me, perhaps with a helpful illustration? 79.75.199.175 (talk) 23:54, 9 September 2008 (UTC)

Have you read antiparticle? I think we're going to need to know what it is that's confusing you particularly, otherwise we're going to end up explaining it the same way as the articles. --Tango (talk) 23:56, 9 September 2008 (UTC)

Well as i understand it antimatter is the opposite of matter, so one would assume antimatter does not have mass while matter does. However i'm not sure if particles such as photons which have no mass are considered antimatter so i might be wrong in my understanding here. If matter is "stuff" then is antimatter is "non-stuff" which also takes up space or what? 79.75.199.175 (talk) 00:23, 10 September 2008 (UTC)

Matter has many properties, and antimatter certainly doesn't have the opposite property of each of them. In particular, it has mass. --Sean 00:32, 10 September 2008 (UTC)

Photons indeed have no mass, and are not normally considered to be either matter or antimatter. Algebraist 00:34, 10 September 2008 (UTC)

Specifically, antiparticles have the same mass as their matter counterparts; they just have opposite charges. I believe charge is the only difference between matter and antimatter. --Bowlhover (talk) 04:29, 10 September 2008 (UTC)

No, other quantum numbers such as spin and colour charge are also reversed in an antiparticle. If only the (electric) charge were reversed then the antineutrino would be identical to the neutrino. Gandalf61 (talk) 10:59, 10 September 2008 (UTC)

There is no real difference between matter and antimatter overall (well, there might be if you get to really complicated stuff, but that's not important to start with), there is only a difference when you compare a particle with its antiparticle. For example, some matter is positively charged (eg. a proton) and some is negatively charged (eg. an election). Likewise, some matter is positively charged (eg. a positron [anti-electron]) and some is negatively charged (eg. an anti-proton). So, it's not that matter has one property and antimatter has the other, that only applies for a particular particle/anti-particle pair. --Tango (talk) 00:38, 10 September 2008 (UTC)

Did you mean 'antimatter' in the 3rd sentence? Wanderer57 (talk) 01:53, 10 September 2008 (UTC)

Adding onto the concept of symmetry between matter and antimatter, why the Big Bang didn't form an equal amount of the two was a mystery until CP-violation was discovered. --Bowlhover (talk) 04:29, 10 September 2008 (UTC)

Matter is a poorly defined word. It usually means anything that has mass and takes up space. By this definition, antimatter is not the opposite of matter; it's just a confusingly-named kind of matter. (And, for that matter, antiparticles are not the opposite of what we usually call particles; they're just confusingly-named kinds of particles.) --Allen (talk) 00:53, 10 September 2008 (UTC)

Perils of Modern Living

Harold P. Furth

Well up above the tropostrata

There is a region stark and stellar

Where, on a streak of anti-matter

Lived Dr. Edward Anti-Teller.

Remote from Fusion's origin,

He lived unguessed and unawares

With all his antikith and kin,

And kept macassars on his chairs.

One morning, idling by the sea,

He spied a tin of monstrous girth

That bore three letters: A. E. C.

Out stepped a visitor from Earth.

Then, shouting gladly o'er the sands,

Met two who in their alien ways

Were like as lentils. Their right hands

Clasped, and the rest was gamma rays.

SteveBaker (talk) 02:05, 10 September 2008 (UTC)

That reminds me of a haiku:

Hippopotamus

Antihippopotamus

Annihilation Algebraist 02:09, 10 September 2008 (UTC)

well, last night i went to an italian restaurant and ate antipasto followed by pasta, and there is definitely a vast quantity of energy being liberated as they meet. Gzuckier (talk) 16:41, 10 September 2008 (UTC)

September 10

reason for .b1 and .g1 primer names

In sequencing of DNA, reads will sometimes have .b1 and .g1 for the forward and reverse primers when producing amplicons. Does anyone know why the letter b is associated with forward and why g is associated with reverse? Thanks. --Rajah (talk) 02:39, 10 September 2008 (UTC)

Carbon dioxide sequestration

There is a lake somewhere inside a volcano cone that sequestered CO2 coming from the volcano at the bottom of the lake do to the temperature and pressure at the bottom. A tremor or some other disturbance released the gas and its spread over the slopes and kill people and livestock. How much risk of this is there in the man-made sequestration of CO2 in ocean bottoms and oil fields and the like? —Preceding unsigned comment added by 71.100.10.144 (talk) 04:20, 10 September 2008 (UTC)

The ocean bottom is risky, if the super carbonated water comes to the surface it will foam up in a big way. ANother risk is acidification of the water with dissolving of shells and bones of sea creatures. With underground storage, it presumably will be pumped back into a gas well that is reasonably well sealed, but as you say a rupture could release the gas again. Natural kinds of these ruptures can crack at the rate of about one kilometer per second and erupt at the surface in a special kind of explosive volcano as a Kimberlite pipe. Graeme Bartlett (talk) 05:30, 10 September 2008 (UTC)

A) The ocean already has ~50 times as much dissolved carbon as the entire atmosphere, so it is implausible that you could pump enough carbon into the ocean to really pose a threat due to gaseous discharge (i.e. Lake Nyos) B) The key word for Kimberlites was "volcano", their source needs to be at least 1000 C. You can't really compare a capped well to a deep, fast moving flow of molten rock and dissolved gas. Dragons flight (talk) 05:48, 10 September 2008 (UTC)

The issue with the ocean is putting too much in too little water. At pressures of 100 bars you can dissolve plenty of carbon dioxide. Cool carbon dioxide breaking out from a well would be dangerous to humans and animals due to suffocation. It does not need to be heated to 1000 degrees. Carbonatites can be as low as 600° degrees. By the way does anyone know how to get the degree symbol that used to be down the bottom of the edit box? Graeme Bartlett (talk) 05:56, 10 September 2008 (UTC)

My understanding of ocean storage is that the CO2 will be simply pumped into the ocean depths, rather than stored in the sub-floor as in above-ground CCS schemes. This avoids the catastrophic-release problem, but presents others such as the massive formation of carbonic acid and uncertainty on the speed of return to atmosphere.

And I'll try to make a degree symbol from the default Insert menu right now: ° Does that look right? Franamax (talk) 06:04, 10 September 2008 (UTC)

Hey thanks that ° works, my menu selection was on wiki markup! To work out the risk there may have to be a proper risk assessment looking at how many people are killed, economic loss, non productive use of energy etc. The lowest risk option may be to put the carbon dioxide in the air. There would not be enough old oil and gas wells to take all of the power station emissions of CO₂ in any case. I much prefer the real soylent green method. Another way is to reproduce the azolla event that stripped the atmosphere of carbon dioxide. Also the end of the cryogenian was a time when huge amounts of carbon dioxide were removed, but this cannot be done now. Graeme Bartlett (talk) 06:14, 10 September 2008 (UTC)

Actually, estimates suggest there are enough geologic repositories to eat all emissions for 100 years or so. Doing so would require drilling new wells, usually into deep (2+ km) saline aquifers, but that's not too big a deal. We annually remove ~3×10¹² m³ of natural gas from the Earth. We have about 20×10¹² m³ of CO2 per year to store. The room exists, at least for a while. (It shouldn't be a shock that those numbers are on the same order of magnitude since natural gas is one of the three principle fuels used to create CO2.) You seem to have a lot of fear and doubt, but I suspect you've never really looked into the technology in serious way. It's not as scary as you seem to imagine, and has a lot of potential for near term mitigation. Dragons flight (talk) 07:14, 10 September 2008 (UTC)

Well, one of the sources of FUD is that these solutions will presumably be provided by private corporations, who will sell their sequestration services for a profit. And when their CO2 reservoir fails (especially if they have over-pressurized them by the 20/3 ratio you allude to above), there will be human deaths near the failure zone, there will be no corporate assets left to claim in the damage suit other than the broken CO2 storage reservoir, and all the CO2 will be back in the atmosphere. Yeah, there is some doubt there. But whatever, lets forget about that old energy conservation idea - that was hippy talk anyway. Franamax (talk) 07:25, 10 September 2008 (UTC)

detectors

what is the job of muon chamber in detectors —Preceding unsigned comment added by 121.52.155.50 (talk) 05:22, 10 September 2008 (UTC)

Are you talking about a muon detector? It detects secondary muons produced by cosmic rays. Applications may include geophysical exploration by measuring absorption by rock in various directions. Graeme Bartlett (talk) 05:35, 10 September 2008 (UTC)

Or are you talking about the Compact Muon Solenoid in the LHC? Muons are emitted from the experiemnts or formed by decay of other particles, and can penetrate further and last longer than most of the other high energy particles. These can be detected further out form the core. Look at this for how this works and what it is used for. Graeme Bartlett (talk) 05:47, 10 September 2008 (UTC)

A hypothetical Higgs boson emits four muons. Graeme Bartlett (talk) 10:11, 10 September 2008 (UTC)

Bayhawk?

What kind of a bird is a bayhawk? 71.113.3.76 (talk) 06:32, 10 September 2008 (UTC)

You might perhaps wish to consider typing "bayhawk" into the search box on the left side of the page. I think you would be pleased with the results. -- Captain Disdain (talk) 08:08, 10 September 2008 (UTC)

CERN's experiment

Anyone knows the exact time when they'll start the experiment? -59.95.99.160 (talk) 06:32, 10 September 2008 (UTC)

It should be just about no

The high intensity experiments aren't coming until the end of the year. Plasticup ^T/C 07:20, 10 September 2008 (UTC)

MSN just a a front-page piece about how the LHC might destroy the world (not kidding). Times like these I have an even lower opinion of the media in general.... --mboverload@ 07:25, 10 September 2008 (UTC)

i'd be more concerned about one of those 30 ton magnets with a defective mounting bracket. Gzuckier (talk) 16:38, 10 September 2008 (UTC)

High Intensity o.O -59.95.99.160 (talk) 07:25, 10 September 2008 (UTC)

I like todays image at http://www.google.com/ PrimeHunter (talk) 10:57, 10 September 2008 (UTC)

Is the word "Google" being sucked into a mini black hole in today's logo? :-) Fribbler (talk) 12:38, 10 September 2008 (UTC)

The world will not end because of the LHC. CERN has prevented such an accident by preemptively destroying the Earth. [32] — DanielLC 16:14, 10 September 2008 (UTC)

it's all part of cern's plan. by creating the web, they led to google; so that when the earth gets destroyed by a black hole, a digital archive will still exist. Gzuckier (talk) 16:37, 10 September 2008 (UTC)

Thanks for the link. Very calming. Like the end of On the Beach. Saintrain (talk) 16:49, 10 September 2008 (UTC)

hair dryer voltage dilemma

i bought a dual voltage hair dryer for travelling. it has a black switch on the handle where it allows you to choose 115V or 230V by turning it w/ a screw driver or a coin. where should it be when in the US???? —Preceding unsigned comment added by 68.97.36.155 (talk) 06:34, 10 September 2008 (UTC)

115V in the US, for sure. 230V is for Europe and you will need a little plug adapter to go between NA flat plugs and Euro round also. Franamax (talk) 06:47, 10 September 2008 (UTC)

Please could more regulars chime in to emphasize that 115V is the correct setting!? Franamax (talk) 07:33, 10 September 2008 (UTC)

As stated in our article on Mains power systems, this is indeed the case. -- Captain Disdain (talk) 08:05, 10 September 2008 (UTC)

Also note that the 115V setting will be correct in bathrooms of many hotels in Europe that cater to Americans. Just look for the "110" or similar label and U.S.-style plugs. I've been surprised how common this is.--Scray (talk) 10:29, 10 September 2008 (UTC)

Yup, have those in Ireland. We call them "shaver sockets", like this one. Fribbler (talk) 12:18, 10 September 2008 (UTC)

115V in North America. Check out this map [33]APL (talk) 13:14, 10 September 2008 (UTC)

Agreeing with 115 volt setting for North America. Edison (talk) 15:10, 10 September 2008 (UTC)

absolutely correct. you will probably not see a 220 volt outlet during your travels in the US and Canada, and if you should perchance find one, it won't accept the normal north america plug which presumably you have for your shaver. Gzuckier (talk) 15:20, 10 September 2008 (UTC)

Only place one is likely to find anything other than 115V in US houses is sockets specifically designed for heavy-duty appliances (electric clothes dryer, electric stove, air conditioner). And the sockets are usually shaped differently so that you can't plug the "wrong" thing (something designed for 115V) into them. DMacks (talk) 16:20, 10 September 2008 (UTC)

boiling water in the states

hello wikipedia, Once of the (many) reasons i find americans endlessly fascinating is that they don't use kettles. As work is going really slowly today, i thought i'd just ask, if you gyus wanted to boil water for cooking (pasta, potatoes etc) what would you do, just put cold water on the stove and heat it up from scratch? Does this not drive you crazy? thanks217.169.40.194 (talk) 08:18, 10 September 2008 (UTC)

An electric kettle can boil the water faster than a gas stove. Its even quicker if you heat a third of your water on the flame, and two thirds of the water in a kettle and then combine them. But simpler if you don't use a kettle at all. Do Americans call a kettle by a different name? Graeme Bartlett (talk) 10:09, 10 September 2008 (UTC)

I'm the American child of East-coast American parents, and we've always had (and called it) a kettle. Same for my wife, a native of California. I think someone is over-generalizing here. Perhaps we need a WP:RS.--Scray (talk) 10:34, 10 September 2008 (UTC)

Non-use of kettles is fascinating? I can assure the OP that some, possibly many, Americans do use kettles. We have the plain kind that you plop onto the stove; we have the electric kind. In bygone days, people left filled kettles on wood stoves or coal stoves to provide some humidity in the winter. (More recently, people bought cast iron kettles to do the same in a retro kind of way, only to learn that cast iron isn't a great idea for holding water over long periods of time.)

My guess would be that most people here cook pasta or potatoes by boiling the water in a large pot on the stove (like a stockpot or a large saucepan). A related guess is that many kettle-users drink tea; people who drink mainly coffee will tend towards coffeemakers.

I agree with the Tea assumption. My aunt lives in Italy, and had to get a kettle shipped over from Ireland to make the sacred brew. In Italy, being very much a coffee country, kettles were nearly impossible to obtain! Fribbler (talk) 12:24, 10 September 2008 (UTC)

As for being driven crazy, we have so many options here that the agony of waiting for pasta water to boil doesn't enter into it. (By "kettle" I'm referring to a vessel with a spout -- e.g., teakettle. Another usage is for a large, open vessel, as in "a different kettle of fish," whence also "kettledrum." Without that kind of kettle, there'd be no cartoons with explorers or missionaries being prepped for dinner.) --- OtherDave (talk) 10:56, 10 September 2008 (UTC)

The big thing with the missionaries is a cauldron. DuncanHill (talk) 15:31, 10 September 2008 (UTC)

It's significantly more energy efficient to use a kettle, which is something Americans have never been too concerned with (just look at average fuel consumptions of cars in the US compared to Europe, say). That may have something to do with the different practice on the other side of the pond. --Tango (talk) 11:34, 10 September 2008 (UTC)

I agree with OtherDave. For one, I would call it a tea-pot or tea-kettle. Simply saying "kettle" needs context to know whether you meant for making tea or if you meant something that Elmer Fudd would boil Bugs Bunny in for stew. For two, everyone I know would likely use a large sauce pan or pot to boil water in for potatoes or pasta. And lastly, I would put a lid on the pot in order to save energy and time. Dismas|^(talk) 12:25, 10 September 2008 (UTC)

Electric kettles are very handy for a cuppa. I assumed that the reason they were so fast is the 250V. What is the wattage of a UK e-kettle? Saintrain (talk) 12:34, 10 September 2008 (UTC)

2-3 kilowatts [34]. Fribbler (talk) 12:36, 10 September 2008 (UTC)

To avoid confusion, note that (in the UK at least) teapot and kettle (never heard it called a "tea-kettle") are different objects. You boil water in a kettle, then pour the boiling water into a teapot together with tea leaves or tea bags to make tea. Gandalf61 (talk) 13:06, 10 September 2008 (UTC)

Good thing you don't have Carolina Wrens over there. You'd have no idea what they were talking about. -- Coneslayer (talk) 13:11, 10 September 2008 (UTC)

When you say "kettle", are you referring exclusively to a "teakettle"? (With a spout and everything. Probably a whistle, too.) Because that's all the word "kettle" means in USA. I notice that the article mentions that it could have a wider meaning in the UK.

For completeness, what would be the pasta making procedure in, say, England? Would you pre-boil some or all of the water in a teakettle before transferring it to a pot? That seems like a good amount of extra effort. APL (talk) 13:12, 10 September 2008 (UTC)

As an energy-conscious German, yes, I pre-boil water electrically before filling into a pot, be it for rice or pasta cooking. You'll do that too as soon as you pay as much for energy as we here do. --Ayacop (talk) 13:44, 10 September 2008 (UTC)

I did manage to find a store in Texas that had electric kettles - they aren't easy to find though. It's really crappy by UK standards - but it works. IMHO, the way you heat water depends on the amount. For small quantities (eg to make a cup of coffee), I use the microwave oven. It's faster than a kettle and vastly more energy-efficient. For medium sized quantities (eg to make four cups of coffee), I use our Texas kettle. At those quantities, it's more energy-efficient than the microwave and faster too. For larger quantities, I use the stove-top and a saucepan - more for speed than for energy efficiency. If I had a larger kettle, I'd use that. SteveBaker (talk) 13:37, 10 September 2008 (UTC)

The Utah teapot - very important to computer graphics geeks!

When you say "tea kettle" in the USA, you're typically imagining an approximately hemispherical vessel with a flat bottom that you set on top of the stove. When we say "kettle" in the UK (they aren't "teakettles") - we know about the US thing - but we're more likely to be thinking of a large cylindrical pot with an electric heating element in the bottom that can boil a couple of pints much more quickly than you could ever do on the stovetop - and with better efficiency too. The fancy modern ones have dual elements for greater efficiency and little float gauges on the side to indicate how full they are. They typically have "curly-cord" power connections (like a short telephone cord) for kid-safety, auto-shutoff when they boil, maybe have a beeper to replace the old whistle. They are sophisticated, highly evolved machines - compared to an American tea-kettle: think "Ferrari versus Trebant". A "teapot" is a (typically) ceramic pot with a spout and a lid in which the tea is actually brewed - you don't ever heat the water in a teapot.SteveBaker (talk) 13:47, 10 September 2008 (UTC)

• widths="100px"
• 
  Kettle
• 
  Teapot

More pictures above .... Gandalf61 (talk) 13:51, 10 September 2008 (UTC)

Some of us Americans might be more likely to refer to the electric water heating apparatus as a "hot pot," as can be seen by the category name in this Amazon listing. Personally, when I need to heat water for tea, I use the quintessential Revereware kettle; if it was good enough for both my grandmothers, it is good enough for me. Personally, I had a hard time searching for a tea pot that I liked, but that's another story. --LarryMac | Talk 14:16, 10 September 2008 (UTC)

The Revereware kettle looks like the sort of thing one would take camping. A few people in Britain still use such kettles on a gas hob at home. DuncanHill (talk) 15:33, 10 September 2008 (UTC)

as a bonus, when attack by redcoats is imminent, the whistle blows "the british are coming!" and it prepares a cup of tea for them. Gzuckier (talk) 16:34, 10 September 2008 (UTC)

I've used an electric kettle in the UK to boil water, and it does a fine job on the 240 volts available in the wall outlet. But in the US the voltage is half as much, and the appliance amperage is usually limited by the 15 or 20 ampere rating of the circuit, so it takes a long time to boil water with an electric kettle. Looking at some adverts, the UK kettles seem to have a 3000 watt rating and the US kettles only a 1500 watt rating. A stovetop burner seems to apply more energy to the water and get it boiled faster. Of course someone could have a 240 volt outlet installed in the kitchen for the electric kettle, but this would be very unusual outside a restaurant. 3000 watts would be 10,240 BTU per hour, and stovetop range burners can be had with 15,000 BTU per hour and higher rating. Granted, the electric kettle should apply the energy to heating the water more efficiently than a kettle setting on a range burner. A microwave might have just a 1000 watt rating. Edison (talk) 14:58, 10 September 2008 (UTC)

UK mains is generally fused at 13 amps, so if you have up to 20 amps that compensates for the lower voltage quite well. 115V at 20 amps gives a maximum of 2.3kW, plenty for boiling water (it's the cheaper end of the UK kettle market, but it'll do just fine). Rather than talking about all these meaningless numbers, let's try some meaningful ones - it takes about a minute to boil a couple of pints in my kettle (far less to boil a mug full for a cup of tea/coffee). How long would it take on your hob (or "stovetop" or whatever you call it)? --Tango (talk) 15:19, 10 September 2008 (UTC)

Just pointing out the UK mains electricity has been delivered at 230 volts rather than 240 volts for something like the last 10 years. To harmonise European standards, those continental supplies that were on 220 volts have been or are in the process of being upped to 230 volts. I seem to remember some spurious talk at the time of the changeover that it would affect the economy because it would take longer to boil a kettle and people would take longer tea-breaks. It would also make you late for work because it would take longer to make toast. Jooler (talk) 15:21, 10 September 2008 (UTC)

Well, it's 230V +/- 10%, so that's anywhere between 207V and 257V, so the change from 240 to 230 is less significant than the natural variation anyway, so I don't think you can use that as an excuse when you're late for work! --Tango (talk) 15:49, 10 September 2008 (UTC)

decadent capitalists not inwenting samovar!! Hahahaha! Gzuckier (talk) 15:23, 10 September 2008 (UTC)

boiling a cup of water

on a related note, whatever happened to those little plug in one cup heater uppers? (let alone the immersion heaters) i can't find any for 110 volts any more, only 12 volt car ones. i'm toying with hooking one up with an old gel cel 12 volt battery and a wall wart, just so's i can get a cup of hot water for beverage purposes at work. Gzuckier (talk) 15:26, 10 September 2008 (UTC)

This [35] would do for making instant coffee, but as it does not actually boil the water is unsuitable for making tea. I would add that as one can buy a perfectly serviceable ordinary electric kettle for a fiver, it does not look like good value for money. DuncanHill (talk) 15:40, 10 September 2008 (UTC)

Or you could take a thermos of your favoured drink to work. DuncanHill (talk) 15:54, 10 September 2008 (UTC)

yeah, but i'm looking for something highly unobtrusive. otherwise the Corporate Preventers will spot it and break into one of those "whatever it is, I'm against it!" routines that they do so well. that's why i've been holding off on the battery/12 volt mug approach.Gzuckier (talk) 16:31, 10 September 2008 (UTC)

UK Spiders

What is the name of those orangey-brown and white spiders that become so prevalent in the UK on cold September mornings? Little blighters were all over my car this morning... sparkl_!sm ^hey! 08:57, 10 September 2008 (UTC)

MEDICINE:GYNAECOLOGIST

What subjects do i require in high school for me to become a GYNAECOLOGIST?Mrs.Rushaksy (talk) 12:06, 10 September 2008 (UTC)

Gynaecology is a medical speciality. So the course you would be taking at third level is medicine. As I understand, in the US (you said high school, so I'm guessing you live there) medicine is a graduate-entry course in that you must first have a relevant degree in say Biology first before you can do medicine. So Biology and Chemistry would be the subjects best suited to pursuing this first degree. Fribbler (talk) 12:14, 10 September 2008 (UTC)

If you truly want to be any sort of specialist, this is a suggestion that I've seen work with many people since I've been working in the medical field:

1. Start volunteering at your local hospital now. You will be doing junk work with no (or very little) pay. But, you will be around doctors and get used to hearing medical-speak. You may realize that you hate the profession and change your mind.
2. Take all the biology and physics that you can in High School. If yours is like mine was (white-trash redneck tiny-town school), you'll have to take classes at a local community college instead of high school.
3. By your senior year, pick the medical schools you want to go to. They will have "sister colleges" that offer the pre-med courses. Now, you know what undergraduate colleges you want to go to. You can work on getting into them.
4. As an undergrad, continue volunteering at the medical schools you want to go to - including applying to do any work you can in research projects. You'll get paid for that work. The goal here is to get your name known with as many people in the school as possible.
5. As you near the end of pre-med, study and study and study for the MCAT. Your score on the MCAT will be a major factor into getting into med school as well as getting free funding for the school.
6. Assuming you do well on the MCAT, you'll be accepted to the medical school. You'll be a general medical student (specialist courses don't matter at the beginning). Try to get an advisor that is in the field you want to work in. He or she will guide you through the courses you need and possibly get you into a volunteer position in the field.
7. From that point, you are set - do well in your classes, keep volunteering, and all those years of working for no pay will finally pay off as you will have the education and the years of experience to bubble up to the top of your class and get a good job anywhere you like.

Keep in mind that that is only one way to do it. You could just have rich parents to donate a building to the medical school in exchange for a degree. -- kainaw™ 12:48, 10 September 2008 (UTC)

physics

whether man can run fast or slow on moon.Plz explain with respect to on earth

—Preceding unsigned comment added by Khubab (talk • contribs) 17:13, 10 September 2008 (UTC)