Wikipedia:Reference desk/Archives/Science/2008 January 15

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January 15

Big Pupils

My pupils are bigger than most people naturally. Could someone explain why? Hmrox (talk) 00:48, 15 January 2008 (UTC)

You are taking drugs?--TreeSmiler (talk) 02:37, 15 January 2008 (UTC)

For the same reason some people have bigger ears, a bigger nose, bigger breasts or a bigger penis. Genetic diversity coupled with different developmental environments. Its been estimated that genetic factors account for as much as an 80% contribution to eye pupil size diversity, suggesting environmental factors account for the rest. Moreover, if you are a female, you may consider yourself lucky as, all things being equal, you will be more attractive to males than your smaller pupiled friends [1]. See also Wikipedia:Reference desk/Archives/Science/2007 September 29#Pupil size. Rockpocket 02:49, 15 January 2008 (UTC)

Is it possible you're a kewpie doll, or an anime character? :-) —Steve Summit (talk) 02:56, 15 January 2008 (UTC)

You teach high school seniors? They are larger than most other pupils. Edison (talk) 03:28, 15 January 2008 (UTC)

Hehehehehehe! Entirely excellent & evocative edit Edison! hydnjo talk 08:47, 15 January 2008 (UTC)

Yep,I`ve got another Physics Magazine Question For You

According,to Physics Weekly I have to get the playing card on top of the pennies,from the embriodery hoop into the graduated cylinder. Also,before that It says three beakers and a tray of toilet paper rolls on tio of those the eggs.You,whack the tray with the broom.The eggs,went into the beaker.I need to draw a demo,there`s a 50,00 dollar prize if I win so it`s really important,that I win so hurry up.Basicilly,I need to know which is the best procedure. —Preceding unsigned comment added by 68.161.128.203 (talk) 02:06, 15 January 2008 (UTC)

Is anyone else utterly disgusted by this question?18.96.7.74 (talk) 02:14, 15 January 2008 (UTC)

Haha, yeah, you don't get much help when you advertise that it's for a cash prize that you want to win, even though you're not willing to put in any effort. That's worse than homework! --24.147.69.31 (talk) 02:29, 15 January 2008 (UTC)

Please, think about the questions in Physics Weekly rather than ask for the answers here. it will do your brain far more good.--TreeSmiler (talk) 02:36, 15 January 2008 (UTC)

A point of clarification: are you, in fact, a troll? That is, do you really expect people to do your work for you (and in a hurry, to boot), or do you just enjoy seeing us get riled up at the breathtaking impertinence of your questions? —Steve Summit (talk) 03:06, 15 January 2008 (UTC)

I can't even find a Physics Weekly magazine. Bellum et Pax (talk) 03:20, 15 January 2008 (UTC)

I had assumed it was foreign, given the poster's non-standard punctuation (using ` instead of ' as an apostrophe, using , as the dollar separator) and dodgy spelling and grammar, but the IP address is from the US, so who knows. --24.147.69.31 (talk) 03:32, 15 January 2008 (UTC)

Well perhaps English just isn't his native language. The punctuation is definitely his? style, see Wikipedia:Reference desk/Archives/Science/2007 December 16#This Is Not A Homework Question and Wikipedia:Reference desk/Archives/Science/2007 December 17#I`ve got a question about a sombero. In any case, I guess we're looking for a monthly publication that comes to the U.S. around the middle of the month Nil Einne (talk) 17:58, 16 January 2008 (UTC)

May I just mail you the $50 rather than doing the work for you so you win it? Edison (talk) 03:27, 15 January 2008 (UTC)

Seeing as he used this IP address to vandalize an article directly before asking this question, I feel it is safe to assume that the question is nothing more than trolling. -- kainaw™ 03:48, 15 January 2008 (UTC)

I'm not so sure, his? last physics weekly question was about the same time last month suggesting to me this is really coming from some magazine. Nil Einne (talk) 18:12, 16 January 2008 (UTC)

..."it`s really important,that I win so hurry up..." We're hurrying sir 68.161..., we really are! ;-)) Meantime you may want to go and do some more vandalizing at Tigers! hydnjo talk 08:38, 15 January 2008 (UTC)

Oh, I am *so* tempted to put something that will make him break the eggs all over the floor... :-) 63.3.19.1 (talk) 01:53, 16 January 2008 (UTC)

He's also migrated over to the Math Desk if you are curious. --24.147.69.31 (talk) 15:48, 16 January 2008 (UTC)

Are we all "free floating brains in space?"

Allan Guth, a cosmologist at MIT, reportedly says [2] that there should be "an infinite number of free-floating brains in space" without even a skull, a body, a space suit or a habitable planet, for every normal brain. How does this make sense? Edison (talk) 04:15, 15 January 2008 (UTC)

Skimming the article briefly, it looks like a combination of two ideas:

1. The proposition, long discussed by SF authors and late-night armchair philosophers alike, that we can't really tell the difference between the real world it seems we exist in, versus an isolated brain which is just imagining it all. [P.S. I figured we probably had an article on it, which Someguy1221 has kindly provided a link to. 04:44, 15 January 2008 (UTC)]
2. The physicist's maxim: "That which is not prohibited is mandatory". Personally, I favor the recasting by Douglas Adams: "In an infinitely large Universe, such as, for instance, the one in which we live, most things one could possibly imagine, and a lot of things one would rather not, grow somewhere." —Steve Summit (talk) 04:26, 15 January 2008 (UTC)

It seems to me you have to assume that life is possible for only a truly infinitesimal span of time with respect to the life of the universe. Since we don't know the ultimate fate of the universe, and we don't know what came "before" (can I say before? Time might not have existed...) As such, this is just another answer, however amusing, to that annoying question. Someguy1221 (talk) 04:36, 15 January 2008 (UTC)

Brains? In space? I think not. If a brain was to be left floating in space, it would quickly freeze, the biological processes that keep it alive would not be able to work, and it would die. Be rest assured your brain is probably nice and warm inside your skull. Astronaut (talk) 15:18, 15 January 2008 (UTC)

Come to think of it, if Allan Guth was correct, wouldn't someone have noticed by now? Surely some of the infinite number of brains whould have impacted a space shuttle and NASA would need to employ people to wash off the mashed brain goo after every mission. Astronaut (talk) 15:23, 15 January 2008 (UTC)

Not necessarily. As was pointed out last time this came up (I'm too tired to trawl the archive), you only have infinitely many brains in infinite space. It's not clear how many of these brains we should expect to find in the (finite) observable universe, for example. Could be ~1. Algebraist 17:06, 15 January 2008 (UTC)

Of course that observable universe is merely a figment of my imagination, so it stands to reason there is only one brain. Dragons flight (talk) 18:31, 15 January 2008 (UTC)

We have an article about this problem, which is distinct from the brain-in-a-vat problem: Boltzmann brain. --Allen (talk) 21:27, 15 January 2008 (UTC)

The problem ceases to be distinct from the brain-in-a-vat problem when a theorist suggests (as in the OP's link) that we are those brains. Someguy1221 (talk) 21:45, 15 January 2008 (UTC)

Couple points:

• Nobody (except maybe some overimaginative journalist) is claiming the "floating brains in space" are literally brains floating in space. They're just some (hypothetical) "thinking" entities, complex enough to notice that the universe (with them in it) is thermodynamically interesting, but less complicated than the world as we know it (i.e. with all its animals and plants and transistor radios and Britney Spears and global warming and Bertie Bott's Every Flavour Beans -- which, as a side note, I think it's absolutely marvelous that plain old Muggles like us can actually buy in stores).
• Even Alan Guth doesn't believe he's correct. As I read the article, he and every other sane cosmologist are madly trying to disprove the "brains in space" theory. Trouble is, the result keeps falling out of their other theories, whether they like it or not. —Steve Summit (talk) 03:51, 17 January 2008 (UTC)

Well, no, they don't have to be human brains physically, but they do have to be human brains functionally, don't they? That's how, as Someguy is pointing out, you get the "we probably are these brains" aspect of the problem, an aspect that seems to be coming from Guth, not Overbye (the journalist). If they're just thinking entities in comparatively simple worlds, where's the freakiness? They'd just be more friendly neighbors. --Allen (talk) 04:34, 17 January 2008 (UTC)

Concussion?

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis, prognosis, or treatment recommendations. If you have injured yourself at work, you should seek any appropriate medical attention, and report your injury to your manager. Unfortunately, random individuals on the internet aren't able to properly examine you or assess your condition; you should take any questions about your health to your doctor. TenOfAllTrades(talk) 16:15, 15 January 2008 (UTC)

Which is what we said! DuncanHill (talk) 16:20, 15 January 2008 (UTC)

Stochastic Resonance

Hi. Is there anyone that could explain stochastic resonance to me in simpler terms than that of the article, if possible? I'm somewhat less interested in fully understanding all the technical aspects of what causes it (I read the article and related links, but don't have a heavy science background), but as it seems like a very interesting, non-intuitive idea I'd like to understand it a little better. Some more examples of specific systems or conditions in which it might occur would be cool if anyone knows of any. Thanks in advance. Azi Like a Fox (talk) 05:36, 15 January 2008 (UTC)

To be as simplistic as possible, you take a system that seems random - such as the number of accidents on I-95 each day. Then, you find a weak, but repeating, increase and decrease pattern. Using that, you predict slight increases and decreases over time. For example, accidents increase on I-95 between Thanksgiving and New Years each year. It is likely that the day with the most accidents won't fall on that time period, but the median number of accidents during the "high accident" time will be higher than the median number of accidents during the "low accident" time. As such, you've pulled a stochastic resonance out of a statistic that appears otherwise to be completely random. -- kainaw™ 11:46, 15 January 2008 (UTC)

I'm not sure that explanation goes far enough, Kainaw — it doesn't say why certain amounts of noise are relevant. Let me try to extend it: consider that on a lonely, country road, there will probably be many days with no accidents at all and a few days with one accident (and ever fewer with more; we'll ignore these). That is, the bad days (1 accident) are much worse than the good days (0 accidents), and there are no in-betweens. Now consider a hypothetical superduperhighway with 500 long, well-utilized lanes of traffic: there will be many accidents a day, and the variation between good days and bad days might be as little as, say, 20400–20600 accidents (which isn't a big difference given the total). Now suppose that the state law is such that on each of these roads (and many more with more moderate amounts of traffic) the police must assign an additional patrol car on the day following any day with a "high" number of accidents (this is 1 for the country road, and, say, 20650 on the huge road). Finally, consider the seasonal variation of the occurrence of these extra police, given Kainaw's model where more accidents occur at the end of the year. Certainly the extra police will be required more frequently when there are more accidents, but if you try to analyze that occurrence, you'll have difficulty in each of the cases I describe. On the country road, because all it takes is one accident to trigger the patrol, there will be scattered extra patrols throughout the year, and they'll never be regular enough that you can (easily) notice that more of them happen at the end of the year. On the busy highway, the number of accidents is so smooth that the 20650 will almost never be hit — even with the increased traffic — and so again you won't be able to detect the increase at the end of the year. But on some street in the middle, which gets 30-40 accidents with a trigger at 41, there will be significantly more "41" days at the end of the year than there are at other times, and there will be enough of them to discern the pattern.

The extra police represent a detector that isn't triggered by the signal alone because it's set too high (above the usual number of accidents). The different roads represent different amounts of (random) noise on the same signal (the holidays' traffic). The country road is all noise, because you can only distinguish 1 and 0; the noise is so much bigger than the signal that you can't see the signal in the result. The huge road is very little noise, because there are so many accidents that they "average out"; adding it to the signal doesn't help the signal ever get above the threshold. The middle-sized road has enough noise to make the signal detectable on occasion, but not so much to trigger the detector at many random times without the signal's help, and so together the signal and the moderate amount of noise produce a clearer resulting signal (where you count the patrols) than you get with the same signal and either more or less noise. The sensitivity of the outcome to the amount of noise, with one particular amount of noise being optimal, is the source of the name "resonance". --Tardis (talk) 20:15, 16 January 2008 (UTC)

Was definitely interested in the signal to noise aspect and how a certain level of noise could actually make the signal to noise ratio better than either less or more noise. Good explanation, thanks a lot. Azi Like a Fox (talk) 10:24, 17 January 2008 (UTC)

Tea, caffeine and health

Slightly odd question: is there a maximum number of cups of tea one should drink in a day in order to avoid dangerous levels of caffeine? Thanks.--Porcupine (prickle me! · contribs · status) 09:32, 15 January 2008 (UTC)

Mine! Follow up to that link - I drink 7-8 cups daily, and I am alive and healthy. Cheers, Ouro (blah blah) 09:47, 15 January 2008 (UTC)

Great - thanks for that!--Porcupine (prickle me! · contribs · status) 09:55, 15 January 2008 (UTC)

No prob. One who loves and respects tea is probably a good person. --Ouro (blah blah) 12:34, 15 January 2008 (UTC)

Not everyone who loves tea is a good person.[3] --M@rēino 23:37, 15 January 2008 (UTC)

Okay, I take that back. --Ouro (blah blah) 07:30, 16 January 2008 (UTC)

I bet he didn't drink proper British workman's tea, well brewed & with full cream milk and sugar, probably some namby-pamby foreign herbal "tea" muck made with lukewarm water. DuncanHill (talk) 07:34, 16 January 2008 (UTC)

I prefer Earl Grey tea, though my favourite brand is German, Messmer. --Ouro (blah blah) 10:07, 16 January 2008 (UTC)

Perhaps I'm wrong but aren't 'namby-pamby foreign herbal "tea"'s a fairly recent phenomon in the west? Nil Einne (talk) 17:35, 16 January 2008 (UTC)

Isnt this a medical question? If not, why not? If so it should be removed per RD guidelines.--TreeSmiler (talk) 00:36, 16 January 2008 (UTC)

I drink ten or more cups a day, and have never died. DuncanHill (talk) 00:38, 16 January 2008 (UTC)

Yet!--TreeSmiler (talk) 00:41, 16 January 2008 (UTC)

It has a 100% fatality rate :) 79.66.24.40 (talk) 02:13, 16 January 2008 (UTC)

As do carrots, apples, and motorbikes, incidentally :) --Ouro (blah blah) 07:29, 16 January 2008 (UTC)

Oil spills

Does anyone know how to remove oil from a cup of sand mix with cooking/crude oil —Preceding unsigned comment added by 58.182.211.238 (talk) 10:57, 15 January 2008 (UTC)

Heat gets some. Heat and a degreasing agent (e.g. acetone) would get almost all. Water based attempts won't do well--BozMo talk 11:20, 15 January 2008 (UTC)

Consider the Surfactant and Detergent articles. --Mdwyer (talk) 18:30, 15 January 2008 (UTC)

It would be hardly worth doing, just get a new cup of clean sand, and buy a new bottle of cooking oil. The natural environment will have bacteria that can metabolize the oil from the sand when it is exposed to ground water and air. If you wanted to recover all the oil to use again extracting it would need some solvent like liquid carbon dioxide that you can totally evaporate without tainting the oil! Graeme Bartlett (talk) 20:08, 15 January 2008 (UTC)

I assumed it was a homework problem. —Steve Summit (talk) 21:14, 15 January 2008 (UTC)

If there are lots of oil, you might try simple filtering first. Then wash the remaining mixer in a bucket of hot water. Remove the sand. Use any technique to remove the oil and water (scooping). You should be left with original amounts of sand and oil once the water is removed. NYCDA (talk) 23:26, 15 January 2008 (UTC)

Your method would also depend on whether you prioritise getting clean sand, or getting clean oil. If, at the end, you want some nice clean sand, and don't care what happens to the oil, then you can follow some of the procedures described above. On the other hand, if you're keen on getting pure oil, free of sand, you might want a more physically-based method, such as filtration. On the hypothetical third hand, your final aim might be getting a jar of sand, and a jar of oil, both relatively free of impurities, and without losing too much of either, which is going to take a slightly more involved method. Confusing Manifestation(Say hi!) 05:48, 16 January 2008 (UTC)

You may want to read about tar sands. There's a section on the extraction process. — Daniel 01:39, 17 January 2008 (UTC)

Grief

Is there a name for the human ability to remain emotionally unaffected by the deaths of thousands of strangers, and yet to be so strongly affected by the death of a loved one? --Bmk (talk) 17:08, 15 January 2008 (UTC)

:Dehumanization has been taught in my psychology course to answer the question 'why do normal people comit horrific acts such as genocide?'. If a person belives another person to be unhuman or a subspecies then it is easier to remove guilt from murdering them. The Nazi government used propganda very effctively to dehumanize the Jews describing them as 'rats' or 'vermin'. The holocaust was implemented by a man called Adolph Eichman, at his trial it was commented on how normal he seemed, to quote Hannah Ardent's book The Banality of Evil: "It would have been comforting indeed to believe Eichman was a monster...The trouble with Eichman was so many were like him and that many were neither perverted or sadistic, that they were, and still are terrifyingly normal." This suggests he led a fairly normal family life and loved those close to him, but was able to permit mass murder by detatching himself from the murder of humans by convincing himself it was not the murder of humans at all, but subhumans. The Rwandan genocide is another exmaple of genocide incited by dehumanization propoganda. With the ruling party using radio to create a negative stereotype of the Tutsi tribe as 'child-eating cannibals'.I hope this makes sense :S. RobertsZ (talk) 17:44, 15 January 2008 (UTC)

I think you answered a different question. The OP isn't suggesting these thousands of deaths were caused by the one who is not suffering; I believe he is referring to the way a normal person doesn't break down in tears whenever he reads the newspaper. Someguy1221 (talk) 18:12, 15 January 2008 (UTC)

Sorry for missenterpreting your question and taking it off track BMK, I would strike it out, but dont know how to... sorry againRobertsZ (talk) 18:22, 15 January 2008 (UTC)

That's ok - it was an interesting answer anyways. --Bmk (talk) 18:35, 15 January 2008 (UTC)

Strike-out is with html: <s>foo</s> makes foo. It's also the 13th button above the edit box. Algebraist 19:44, 15 January 2008 (UTC)

Thanks, I really should try using the sandbox at somepoint trying all this out, RobertsZ (talk) 20:11, 15 January 2008 (UTC)

Sanity? Honestly I mean if people treat the death of complete strangers the same as they did loved ones they'd be driven insane with despair and grief. As they said in the film Swordfish (film) "thousand die every day for no reason at all, where's your bleeding heart for them?" - if they've not taken this from somewhere this statement is far 'deeper' than the rest of this movie... (To put that statement in context here's the lines preceeding...

Stanley: How can you justify all this?
Gabriel: You're not looking at the big picture Stan. Here's a scenario. You have the power to cure all the world's diseases but the price for this is that you must kill a single innocent child, could you kill that child Stanley?
Stanley: No.
Gabriel: You disappoint me, it's the greatest good.
Stanley: Well how about 10 innocents?
Gabriel: Now you're gettin' it, how about a hundred - how about a THOUSAND? Not to save the world but to preserve our way of life.
Stanley: No man has the right to make that decision; you're no different from any other terrorist.
Gabriel: No, you're wrong Stanley. Thousands die every day for no reason at all, where's your bleeding heart for them? You give your twenty dollars to Greenpeace every year thinking you're changing the world? What countries will harbor terrorists when they realize the consequences of what I'll do? Did you know that I can buy nuclear warheads in Minsk for forty million each? Hell, I'd buy half a dozen and even get a discount!

ny156uk (talk) 00:35, 16 January 2008 (UTC)

Might as well quote the famous bit attributed (probably incorrectly) to Stalin: "The death of one man is a tragedy, the death of millions is a statistic." Anyway, from a psychological point of view it probably has to do with the idea of kinship—you care more about those in your "family" (which does not necessarily have anything to do with actual blood relations) than you do out of your family. All sorts of dynamics result from this simple fact (racism probably has a similar mechanism behind it). -24.147.69.31 (talk) 02:12, 16 January 2008 (UTC)

10x Loupe Eyepeice

I have a 10x Loupe eyepiece which I am using to make a simple Refracting telescope. How can I calculate the focal length of this eyepiece? Thanks, 86.154.247.108 (talk) 21:43, 15 January 2008 (UTC)

If you have enough information, you could use the lensmaker's equation. If not, you can shine a pair of laser beams (or a planar beam if you have a nice optics lab available) parallel into the lens and see where they converge. For a lowtech measurement, if the lens is thin enough, place a lit candle on one side of the lens, with the lens level with and pointing at the flame. Hold a piece of paper on the other side and see where the light cast through the lens is brightest. Using the distance to the candle as your "object" distance, and the distance to the brightest casting as your "image" distance, you can compute the focal length with the equation found in the previous link. But note this is not the most accurate experiment, and the equation itself is an approximation. Someguy1221 (talk) 21:53, 15 January 2008 (UTC)

Could you ask an optician? They have some cool gadgets for measuring focal lengths. Julia Rossi (talk) 07:21, 16 January 2008 (UTC)

Looking for a study or news article relating to nightmares

I saw something in the news online within the past two months (probably less) that said something along the lines of nightmares and other dreams possibly being the brain's way of doing disaster preparedness, giving the brain training on how to deal with emergencies. I don't know what the scientific origins were, but one of the comments by researchers was wondering how it would help seeing as so many of our dreams we don't remember. Any help would be great!!! —Preceding unsigned comment added by 154.5.108.184 (talk) 22:27, 15 January 2008 (UTC)

Have you seen the article Nightmare – don't know if it's strictly relevant to your question, but there's a ref source linked to this statement "A recently proposed treatment consists of imagery rehearsal.[1] This approach appears to reduce the effects of nightmares and other symptoms in acute stress disorder and post-traumatic stress disorder.[2]". And more, although it looks more like the other way around: helping people to deal with traumatic experiences and so reduce nightmares, but, over to you. Julia Rossi (talk) 07:44, 16 January 2008 (UTC)

Thanks very much for looking, Julie, but that's not really what I was looking for. Very interesting, but kind of the mirror image of the article I saw. Cheers though. —Preceding unsigned comment added by 154.5.108.184 (talk) 01:04, 17 January 2008 (UTC)

Point taken. Tried lucid dreaming and brain training but no specific article that'd help you so far. Do you remember the publisher of the article? Another link is a pdf here?download=Stress%20report%204.2.pdf that talks about applied neurofeedback training the brain to deal with stress – but to your query re brain having its own preparedness faculty through nightmares, as yet nothing. Zzzzz Julia Rossi (talk) 08:28, 17 January 2008 (UTC)