Wikipedia:Reference desk/Archives/Science/2009 September 17

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September 17

Sunscreen stability?

Hypothetically, if I apply sunscreen in the morning (before sunrise) and stay inside a dark room with no windows, will I have any UV protection by the afternoon? I was shopping for sunscreen today and noticed many formulas are marketed with "UV Extenders" that supposedly keep sunscreens from breaking down in the sun. Is this true? Are sunscreens really that short lived -- even without exposure to UV light? --70.167.58.6 (talk) 00:08, 17 September 2009 (UTC)

This is a complete guess based mostly off of my own readings of sunscreen bottles, but I imagine a large portion of the reason why sunscreen wears off and needs to be reapplied is due to your activities when wearing such things, namely swimming and sweating. If you sit in the dark for a few hours, you probably will have some protection(after all, you're supposed to apply (half) an hour before exposure) but some will have worn off due to your bodily secretions. ~ Amory (user • talk • contribs) 02:16, 17 September 2009 (UTC)

Wouldn't the lotion also absorb and dissipate? Baseball Bugs ^{What's up, Doc?} carrots 03:47, 17 September 2009 (UTC)

Probably, although I suppose that depends on how well it puts the lotion on its skin. ~ Amory (user • talk • contribs) 04:46, 17 September 2009 (UTC)

Quantity certainly matters. You've probably seen cricketers, for example, with a thick slather of sunscreen on exposed tips that are in the sun for hours, or folks on the beach that put a big glob of it on their noses. Nothing's going to penetrate that for awhile. Baseball Bugs ^{What's up, Doc?} carrots 04:51, 17 September 2009 (UTC)

Sorry but I'm a bit confused by your question. At first in the hypothetical example it sounds like you are asking whether sunscreens break down after application without exposure to UV/sunligh. Then you say many sunscreens have formulas to reduce break down under sunlight/UV light and whether it's true they break down I presume you mean in the sun/UV light. Then you ask again whether sunscreens are short lived without exposure to sunlight/UV light. Do you want to know about breakdown to sunlight/UV light, due to other reasons or both? Anyway as has been mentioned, sunscreens may wear off for a number of reasons. If you want to know about whether they break down upon exposure to UV/sunlight, the answer is yes they usually do. [http://www.ewg.org/cosmetics/report/sunscreen09/investigation/summary-of-findings] says 17 ingredients approved for use in the US break down significantly within 30 minutes. In particular "works by first absorbing the sun's energy so it doesn't penetrate our skin, and then releasing that captured energy by breaking apart, reacting with other chemicals in the sunscreen, or even kicking off free radicals. Some active ingredients are more stable than others, but nearly all break down to some extent in the sun." Unfortunately their figures are screwed so it's not clear how common these are used. This [1] and [2] may also be of interest. I have the idea this may have came up before so you may want to search the archives. Nil Einne (talk) 06:57, 17 September 2009 (UTC)

Number of planets

As solar systems go, does ours have a lot of planets? Or do we not have enough data to be able to make such a judgement? Dismas|^(talk) 00:26, 17 September 2009 (UTC)

No, we don't have enough data. However, a very large ( >> 10 ) number of planets seems unlikely, since, by definition, a planet must clear out its vicinity, and there is only so much vicinity available within a protoplanetary disc. --Dr Dima (talk) 00:33, 17 September 2009 (UTC)

Actually, the IAU didn't extend their (extremely bogus, IMO) definition outside our solar system.

I don't recognize the IAU definition, of course, so the problem could be reconsidered using a more sensible geology-based definition. --Trovatore (talk) 00:37, 17 September 2009 (UTC)

I don't see why it particularly matters what you recognise. You aren't the OP. In any case, if you want to use another definition, you should at least tell us what that definition rather then expecting us to guess what this 'more sensible geology-based' definition is, since none is given at planet Nil Einne (talk) 02:32, 17 September 2009 (UTC)

My point is that the IAU is without authority to redefine the word planet, and we should not be paying as much attention to them as most people seem to be doing. --Trovatore (talk) 03:54, 17 September 2009 (UTC)

As to what a more sensible definition would be, the "hydrostatic equilibrium" one that they rejected was not too bad. Except that it shouldn't matter whether the body is in orbit around another non-stellar body or not. My preference would be that the Moon, Titan, and the Galilean moons of Jupiter should all be recognized as planets. But I would like to see this happen by natural linguistic evolution, certainly not by the arrogant vote of some organization. --Trovatore (talk) 04:00, 17 September 2009 (UTC)

What I see is an arrogant notion that the IAU is not allowed to make their own decisions. They never said anything about the use of the word planet outside the IAU. They stated that when they use the word "planet", it must have a specific meaning that they chose to use. If you want to call any rock you find floating around in space a "planet", you are free to do so (as long as it is not in paperwork to be published to/from the IAU). Nobody from the IAU is going to toss you in jail. -- kainaw™ 04:11, 17 September 2009 (UTC)

If in fact the IAU definition were applied only in an IAU context, that would be fine (even though they still picked the wrong one). Unfortunately it seems that it is being followed much more generally. I deplore that fact — we should not follow them in this. --Trovatore (talk) 04:19, 17 September 2009 (UTC)

I don't understand why you consider a vote by a panel of experts to define a formerly rather fuzzy term to be "arrogant" - where as you (a single individual) can make up your mind without reference to the rest of the community and NOT be arrogant! That makes no sense. Anyway - there is now a perfectly usable definition for the word 'planet' - and here on the RD, we should use it because that's the scientifically correct thing to do. If you choose to use the word in some other context - you'd better make that clear on each and every occasion to avoid the chance of ambiguity. SteveBaker (talk) 12:11, 17 September 2009 (UTC)

Steve, the fact that the IAU has made its decision does not make it "the scientifically correct thing to do". Science is not conducted by votes. The IAU's action was completely improper, and we should resoundingly reject it. --Trovatore (talk) 20:13, 17 September 2009 (UTC)

Regardless of how we feel about the IAU, this discussion is not answering the original poster's question. Nimur (talk) 20:33, 17 September 2009 (UTC)

Our solar system has at most 4 planets (probably fewer) that we could detect if they were in the same orbit around another sun-like star. We have found stars with several planets, so it would seem we aren't that unusual. Until we have some data about smaller planets around other stars (work is being done - give it a couple of years), that isn't much more than a guess. --Tango (talk) 00:40, 17 September 2009 (UTC)

Right now, we can't detect planets even as small as Earth - let alone Venus, Mars, Mercury and stuff like Sedna and Pluto. Worse still, the further the planet is from the star, the harder it is to detect - so while we might have a shot at spotting another Mercury - we have a long way to go to be able to spot another Sedna...it took quite a lot of effort to find it right here on our doorstep! SteveBaker (talk) 00:55, 17 September 2009 (UTC)

Well, to be sure, apparently we have detected things that are pretty close to Earth size (1.7X)... see COROT-7b, which was in the news just today. --98.217.14.211 (talk) 01:20, 17 September 2009 (UTC)

Mass and orbital radius are generally the more relevant considerations, though, and COROT-7b is 5 times Earth's mass and 70 times closer to its star in those cases. As Steve notes, we're still a long way from finding Earthlike planets in Earthlike orbits, much less the smaller stuff. I think a previous discussion even established that it's not likely we could find a planet with Jupiter's mass and orbit from any astronomically appreciable distance. — Lomn 02:33, 17 September 2009 (UTC)

Diameter is significant for the newer "transit method", which is likely to be how we will detect Earth-like planets. The Kepler Mission should be able to detect Earth-like planets, but it will take some time - such a planet will have an orbital period of about a year (by definition!) so it will only transit about once a year. We need two transits, at least, to get meaningful data. --Tango (talk) 02:39, 17 September 2009 (UTC)

Well, actually - the difficulty of detection for the transit method is proportional to the cross-sectional area of the planet versus that of the parent star. So a 1.7 times bigger diameter planet is still almost three times easier to detect than an earth-sized one - and the fact that the parent star is considerably smaller than our sun makes it even easier to detect using this method because the planet occludes a greater percentage of the parent starlight. When you combine both of those things - I think you'll find that COROT-7b is at least five times easier to detect (in terms of required telescope sensitivity) than Earth would be. SteveBaker (talk) 12:11, 17 September 2009 (UTC)

I never said otherwise - I was just saying that diameter is a highly relevant consideration. Lomn was thinking of the wobble method, which isn't the way we're going to detect Earth-like planets (and isn't how COROT-7b was detected). I think the main thing that makes COROT-7b easier to detect is its orbital period of 20 hours. That means we can easily detect a large number of transits, which allows us to do fancy data analysis to remove noise and find the signal. An Earth-like planet will have an orbital period of about a year, which means we will only have a few transits the study so the signal:noise ratio needs to be much higher. A 5 times louder signal isn't that big a difference - these things are usually compared in terms of orders of magnitude. --Tango (talk) 16:18, 17 September 2009 (UTC)

Thank you to those of you who answered my question. Dismas|^(talk) 05:22, 20 September 2009 (UTC)

Short Fever

I recently experienced a short (12 hour) intense fever, with temperatures of around 102. The fever was preceeded by a slight headache, and followed by a period of about 12 more hours of achy muscles and slight dizziness. Then it was gone, with nothing left but a slightly upset stomach (no vomiting, holding food without problems). The upset stomach has since passed, and left me thinking- wow, what just happened? There were no other flu symptoms beside the fever. Was it merely a passing bacterial infection that my immune system dealt with quickly? I realize advice cannot be given out, but explanations are appropriate I assume. Thanks 72.65.96.147 (talk) 02:47, 17 September 2009 (UTC)

No, explanations are not appropriate. A visit to a doctor is appropriate. You are explicitly asking for a diagnosis which we cannot provide. Sorry. --Dr Dima (talk) 03:10, 17 September 2009 (UTC)

This being the "change of seasons", there are plenty of bugs going around, like always. The symptoms vary in intensity and duration. Anything resembling the flu can be dangerous. See a doctor. Baseball Bugs ^{What's up, Doc?} carrots 03:45, 17 September 2009 (UTC)

Certainly we can't diagnose, whereas a medical doctor can. But are you all really sincere when you say "see a doctor"? Personally I would never bother the medical profession (or more to the point, subject myself to the inconveniences associated with the medical profession) based on the facts described. This is not advice of any sort; I'm just reporting what I would do. --Trovatore (talk) 05:07, 17 September 2009 (UTC)

Since they're being paid, going to a doctor is not "bothering" them, it's their job. And it's true a lot of us don't go to doctors when we maybe should. The issue is that the guy is asking for a medical opinion, and no one here (so far) is qualified to give an opinion that's anything more than "folk wisdom", so to speak. So if he wants a medical opinion, he needs to go to a medical professional, such as a medical doctor. Baseball Bugs ^{What's up, Doc?} carrots 05:15, 17 September 2009 (UTC)

As I explained in the parenthetical, it's not them so much I'm worried about being bothered; it's me.

My strong suspicion is that I would not get any satisfactory answer from a medical doctor on a question like this. He'll tell me a bunch of things it could have been, and explain that there's really no practical way to find out which, but since I'm already feeling better, why do I care? For this I should take time out of my day, get poked and prodded, and pay money? --Trovatore (talk) 05:21, 17 September 2009 (UTC)

Only if you choose to. No one can force you to go to a doctor. But if you want medical advice, wikipedia is not the place to get it. If you want to read wikipedia articles that describe various ailments, you're free to do so. That's not the same as giving medical advice to an individual. The articles merely explain some things about the diseases. It doesn't tell you what disease you have, if any. To get a diagnosis, you must see a professional. That doesn't guarantee a satisfactory result. But it's his job, so it's the best shot you've got. Baseball Bugs ^{What's up, Doc?} carrots 05:31, 17 September 2009 (UTC)

(to Trovatore) If you don't even trust a medical doctor to give a reliable solution to a problem like this, then what about random strangers on teh intrewebz makes you think that you are going to get a BETTER solution!?!? If doctors aren't going to give an acceptable answer, then you aren't likely going to get one, period... --Jayron32 12:18, 17 September 2009 (UTC)

Well, as for me, the answer is obvious. I can't go to much more than one doctor but I can ask many, many people on the net. Asking on the net is far less costly in time and money than going to one doctor, let alone to many. Asking on the net gives other people the chance to learn something, too. Asking on the net is far more safe than an overcrowded waiting room full of sick people with all kinds of infections. And what you'll get as diagnosis from a doctor in this case would be acute fever which is precisely what you already know. And as in this case the illness has already gone and it's pure curiosity to guess what it could have been I wouldn't see any use spending up to several average peoples wages on doctors. 93.132.128.221 (talk) 16:30, 17 September 2009 (UTC)

Absolutely right. Moreover, using medical care when you don't need it drives up the cost; basic supply and demand. Completely off topic -- very interesting article on health care in The Atlantic this month which I strongly commend to anyone thinking about the problem. The author wants to get away from using insurance to pay for routine medical care (which he says is like using your accident insurance to put gas in your car). If medical care were treated like a consumer good, there would be actual market discipline on the pricing.

So as to my completely unqualified guess, with ABSOLUTELY NO WARRANTY -- it's possible you had food poisoning. I recall reading somewhere that the so-called "24-hour flu" is usually food poisoning. It's hard to understand the lack of gastrointestinal symptoms, though. --Trovatore (talk) 20:06, 17 September 2009 (UTC)

If I visited a doctor right now, he/she would tell me I am perfectly healthy and then hand me an exorbitant bill. I have no reason to visit a doctor, because I am now fully recovered. I am merely in retrospect pondering what hit me. Trovatore gave me a straight answer. 72.65.96.147 (talk) 22:18, 17 September 2009 (UTC) 72.65.96.147 (talk) 22:17, 17 September 2009 (UTC)

Sound in free-space/vacuum

This is a completely hypothetical question about a scenario I'm trying to work into a piece of writing, and I'd be much obliged if someone could help a person who's very much not a scientist wrap his head around this subject. I've looked through all the articles on sound, vacuum, interplanetary and interstellar mediums and a number of other pages. The understanding I think I have is: Sound cannot travel through such a low-density, low-pressure body of matter like space because there is not enough for the vibrations to bounce off of, and therefore travel through. Theoretically, knowing that such a scenario is completely outside of the realm of possibility, what would have to happen to the interstellar medium in order for sound to travel through it? I would guess that the medium would have to increase in density and/or pressure, so that it more resembled something that could transmit vibrations, like atmosphere, air, water, etc... Is there a named process for these increases, when applied on a smaller scale? And then, radio waves can travel through space because they are NOT vibrations, and simply require a receiver to be turned into something a human would recognize as sound, right? Apologies for the rambling...99.62.112.181 (talk) 03:01, 17 September 2009 (UTC)

Sound is simply harmonic vibrations occuring in a substance. Nothing more than that. If you have matter (i.e. anything made of atoms) which is vibrating, you have sound. No atoms, no sound. The vibration is carried because the atoms bump off of each other, transmitting the energy from one atom to another. In "outer space", there are still atoms, but they are so far apart from each other that they cannot reliably transmit such vibrations; any energy you impart to one atom cannot be propagated in any predictable fashion because of the fantastically low densities of space. Basically, the signal-to-noise ratio is nill. So there is nothing you could do to "space" to make it transmit sound short of making it "not space" anymore, i.e. making it actual matter and filling it up with atoms and molecules and stuff. --Jayron32 03:48, 17 September 2009 (UTC)

Also, to answer your second part, radio waves are merely electromagnetic waves like light, that is they aren't really "waves" in the classical sense any more than a photon is a classical particle like a bowling ball is. Light does not "propagate" through matter like sound does. We use the term "wave" to describe both sound and (sometimes) light, but they are really VERY different phenomenons... --Jayron32 04:01, 17 September 2009 (UTC)

So, for example, if you're in a space suit on a walk-in-space on the shuttle or something, and some object bangs your helmet, you'll hear it, because there is air in the suit. But someone outside the suit won't hear that bang. Here's a poser, though. There are certainly individual atoms and/or molecules floating around in the so-called vacuum of space. They are just very far apart. But how far apart? Or has this ever been studied? Baseball Bugs ^{What's up, Doc?} carrots 04:14, 17 September 2009 (UTC)

Our article on Outer space notes that the matter density is on the order of "a few" hydrogen molecules per cubic centimeter; if we take a few to mean a countably small number (say a few hundred or a few thousand) then it becomes obvious how far apart these atoms really are when, at sea level pressures, a cubic centimeter of hydrogen contains 10¹⁹ molecules; by extension that means that the open space between those molecules is on the order of one billion billion times greater. This becomes even more understandable when put on human scales. Thus, if the distance between hydrogen atoms on earth were, say, 1 mile apart, then the distance between hydrogen atoms in space on the same scale would be roughly the distance between the Earth and the other side of the Milky Way galaxy. --Jayron32 04:25, 17 September 2009 (UTC)

OK, what I'm thinking is this, tell me if I'm wrong: sound comes from particles "banging into" each other. The closer together the particles are, the better resonance you get. For example, sound travels better under water than through the air, right? Consider an explosion of some kind. It makes quite a racket. If the air were thinner, it would make somewhat less of a racket. But if it were a greater explosion, it would make a greater racket. So what I'm suggesting is that the incredible amount of energy from, say, an exploding sun, might be sufficient to cause some degree of sound waves in the almost-vacuum of space. Not that you would live long enough to hear much of that sound if you were out in the midst of it. But that's the concept. What do you think? Baseball Bugs ^{What's up, Doc?} carrots 04:44, 17 September 2009 (UTC)

Not really. For something to propagate, you need to be able to create at minumum a "pulse" which can propagate through matter. An exploding star would generate such a "pulse", but regardless of how strong that pulse was, you would still need the surrounding matter to, when pushed, be able to hit other matter in such a way as to continue the pulse. Regardless of how hard it was pushed, the hydrogen in the deep of space is so diffuse that it can't be counted on to hit other hydrogen molecules in that manner. --Jayron32 12:16, 17 September 2009 (UTC)

I see. The way you would probably get a sound in space from that explosion would be if the energy started slamming those molecules closer together - in effect, creating a temporary "atmosphere" in that region, which goes back to the original point - that the molecules have to be close together. I'll postulate something else here, though - that you could, possibly, get some molecular collision in space as it is now, and hence some degree of sound - but probably at such low volume level as to be virtually undetectable. No U.S.S. Enterprise "whoosh", no matter how fast it's going. Baseball Bugs ^{What's up, Doc?} carrots 13:19, 17 September 2009 (UTC)

Sound in an ideal gas is not transmitted by particles bumping into each other. It's transmitted by simple motion of the particles. There are always gas particles bouncing off the diaphragm of your speaker. When you push the diaphragm toward the gas you reflect a few more particles per unit time than usual. Later, a few more particles per unit time than usual hit the receiver, pushing it backwards. The speed of sound is basically just the average speed of the gas particles, which is a function only of the temperature and the type of particle. It doesn't depend on the pressure or density. However, as the pressure or density goes down the received signal energy gets weaker (fewer particles) to the point where it's hardly worth trying to detect it. In principle, though, the interplanetary medium and interstellar medium do transmit sound (with a pretty high speed, but terrible signal strength). -- BenRG (talk) 13:28, 17 September 2009 (UTC)

For a truly ideal gas, wouldn't you get massive diffusion of the pulses because of the varying speeds of the particles? --Tardis (talk) 18:02, 17 September 2009 (UTC)

Remember that the mean separation between particles goes as the -1/3 power of the number density, so the billion billion factor difference in number density corresponds to "only" a million factor difference in distances. --Tardis (talk) 18:02, 17 September 2009 (UTC)

(ec)Well, come on, there's enough in common to use the word wave for both. Both phenomena are sinusoidal oscillations in something (pressure in the case of sound, electric/magnetic field strength in the case of EM). In similar ways they diffract around obstacles and interfere to produce an interference pattern. They actually have quite a lot in common.

There are also important differences, as you note; besides the one relevant to the original question (sound needs a material medium; EM doesn't), there's also the fact that sound waves are longitudinal whereas EM waves are transverse (so for example there can be no such thing as "polarized" sound). --Trovatore (talk) 04:17, 17 September 2009 (UTC)

In high school science, they used to teach us that literal "waves", like in those little wave-tank machines with the two vibrating probes (whatever those machines were called) are essentially analogous to electromagnetic waves, or simplified explanations, but not precisely the same thing. Baseball Bugs ^{What's up, Doc?} carrots 04:38, 17 September 2009 (UTC)

In one tiny respect, those are actually closer to EM waves than sound waves are to EM waves -- at least they're transverse. You still can't polarize them, though, because there's only one direction for them to be transverse in. --Trovatore (talk) 04:42, 17 September 2009 (UTC)

There's hardly any difference between light and sound. Light is a vacuum sound wave. Every kind of sound has a particle nature (see phonon). Photons are just phonons of light. Light can travel through vacuum because it's the vacuum that's waving. Ditto gravitational waves. Ditto everything, actually—electrons are also vacuum waves and that's why they can travel through the vacuum. -- BenRG (talk) 13:28, 17 September 2009 (UTC)

As I understand it, a gravitational wave is essentially a sound pulse traversing the spacetime continuum -- but generating a high-frequency gravity wave would be a pretty amazing feat. Looie496 (talk) 05:13, 17 September 2009 (UTC)

Two astronauts in vacuum could talk to one another via sound waves if the fronts of their helmets were connected by a tightly stretched string or wire. The sound should travel fine for many miles, since there is no wind, which interfered with 19th century acoustic phones on Earth. Edison (talk) 00:23, 18 September 2009 (UTC)

If you plan to write a fiction or science-fiction story, I suggest the following: by piloting a spaceship or giant mecha or whatever, the computer could detect all objects, explosions, lasers etc. around you, and simulate the sounds for you to give a quite useful auditive feedback about your surroundings. Or if you are writing steampunk, there could be all the luminiferous aether in space you want :) --217.91.40.206 (talk) 21:40, 23 September 2009 (UTC)

Moons of Mars

Keep reading articles on Mars dont know why but cant help it leaps out at me - the article that appears in wiki talks about the moons having starnge orbits for captured asteriods; My question is what would be the expected orbit of captured bodies around a planet thus making the moons of mars orbit strange?Chromagnum (talk) 05:37, 17 September 2009 (UTC)

I don't know the answer but I just thought you'd like to know that this site is not "wiki"; this site is called Wikipedia. A wiki is any website using wiki software. There are thousands of them.--162.84.164.115 (talk) 06:06, 17 September 2009 (UTC)

You are exactly right. Wikipedia uses wiki software but isn't wiki any more. Last time I tried to create a redirect I was not allowed to so I left it and I feel appalled by the ever increasing rules and regulations. 93.132.128.221 (talk) 06:41, 17 September 2009 (UTC)

People on Wikipedia often refer to Wikipedia as "wiki". It's not a problem. And if the meaning of the questioner is clear, don't get pedantic about picking apart the question. It doesn't help anyone and it's a jerk thing to do. It seriously does not make you look clever—much to the contrary, in fact. --98.217.14.211 (talk) 13:51, 17 September 2009 (UTC)

My appologies i was typing fast and used wiki for short wont happen again thanks for your usefull knowledge that helps me through my day to day lifeChromagnum (talk) 06:08, 17 September 2009 (UTC)

Just for kicks a site using "Wiki" software is not refered to as a wiki :) least could have given the correct answerChromagnum (talk) 06:12, 17 September 2009 (UTC)

What? Yes it is. Vimescarrot (talk) 10:45, 17 September 2009 (UTC)

Instead of a bit bucket, they have a wiki basket. Baseball Bugs ^{What's up, Doc?} carrots 06:14, 17 September 2009 (UTC)

The way I read the article, the orbits are nearly circular, which could be considered unusual, as captured objects might be expected to be significantly elliptical. Baseball Bugs ^{What's up, Doc?} carrots 06:18, 17 September 2009 (UTC)

Before we sent rockets to Mars and determined its surface nature and that of its moons close-up, i.e. when some people still thought there could be humanoid life on Mars, there was a hypothesis that Deimos and Phobos were artificial. That now seems unlikely. But the near-circular orbits appears to be a poser. Baseball Bugs ^{What's up, Doc?} carrots 06:20, 17 September 2009 (UTC)

Drilling down from your original link, you can find articles on Phobos and Deimos, each of which describes the unusual characteristics of their orbits. It appears that the expected orbit, as you ask, would be more elliptical, less aligned with the equatorial plane and possibly at a greater radius from the planet for starters. For comparison with the other moons of the solar system you may find this comparison helpful. Erector Euphonious (talk) 12:06, 17 September 2009 (UTC)

Thanks good link Euphonious ch:)

Cute animals

What evolutionary factor could have possibly made humans sympathetic to cute little animals? Also, is it possible that other animals think other species of animals are cute as well? If so...why!? -- penubag  (talk) 07:25, 17 September 2009 (UTC)

The article on cuteness is a bit short but basically what you are asking for. 93.132.128.221 (talk) 07:46, 17 September 2009 (UTC)

That article doesn't fully answer my question but it is interesting, thanks. -- penubag  (talk) 08:22, 17 September 2009 (UTC)

Seems to provide a full explanation that I can see. What do you see as a problem? It's fairly straightforward, infants are a bundle of problems and annoyances and we have a built-in drive to nurture them. As to other animals finding the young of another species cute don't you often see these 'cute' pictures where one animal has adopted the young of another? Dmcq (talk) 10:32, 17 September 2009 (UTC)

query? The article says "That is, humans prefer animals which exhibit pedomorphosis." I don't think this is right - Giant pandas do not have pedomorphosis. Nor do humans appear to prefer animals which retain their gills from a larval stage, is there a better term.87.102.94.154 (talk) 10:38, 17 September 2009 (UTC)

Atavism? --TammyMoet (talk) 11:20, 17 September 2009 (UTC)

Interesting, but no. Unless maybe you mean Atavistic regression as a behaviour83.100.251.196 (talk) 11:45, 17 September 2009 (UTC)

I had considered adding that to the link, actually. It's one reason why we enjoy fussing dogs and cats, especially cats, whose behaviour in the wild is completely different to their behaviour around their staff (kneading, purring, dribbling etc). --TammyMoet (talk) 13:20, 17 September 2009 (UTC)

Domesticated dogs are interesting because they are supposed to have an arrested development stuck at the 'object play' stage.[3] - which links in vaguely with the cute(likeable)=child like theory.83.100.251.196 (talk) 17:37, 17 September 2009 (UTC)

The theory is that human beings find things cute that resemble human baby characteristics becuase this illicits a caring response - such characteristics include round head, large eyes, small nose, slightly fatty build, and maybe relative lack of hair.83.100.251.196 (talk) 11:45, 17 September 2009 (UTC)

For example, little tarantulas are just darling. Ugh. I think it has to do with attractive appearance in general. Why are baby ducks cuter than baby geese? Because adult ducks are attractive and baby ducks look like miniatures of the adults. Not so much so with geese. Baseball Bugs ^{What's up, Doc?} carrots 13:15, 17 September 2009 (UTC)

I don't think there are any objectively cute animals -- it's complete and utter editorialization, much like referring to the weather as "nice" or "crummy." In those societies in which children play with furry stuffed animals, perhaps an association is made to those animals that appear similar to such a toy. In a theoretical society in which children are restricted to playing with other things, those things may then take on a "cute" factor. Another aspect would be the size of animals -- small size may ingenuinely suggest docility, such as small pythons and alligators. DRosenbach ^{(Talk | Contribs)} 13:32, 17 September 2009 (UTC)

I find baby geese pretty cute! --98.217.14.211 (talk) 22:29, 17 September 2009 (UTC)

Does sound play a factor in that too? When I hear gull chicks plaintively begging for food or calling for their mothers, I get the 'awww, the poor cute little scared, hungry thing' response. --Kurt Shaped Box (talk) 22:43, 17 September 2009 (UTC)

For a truly comprehensive examination of the "Laws of Cute", you simply have to read http://cuteoverload.com/tag/the-rules-of-cuteness/ - it's true and really funny. SteveBaker (talk) 18:16, 17 September 2009 (UTC)

Eye pain / Menstrual Cycle

My girlfriend told me today that she often gets a rather strong pain in her eye a day or so before her period. It doesn't happen every time, but whenever it does it's pretty much a failsafe predictor that she'll start in the next 12-24 hours. How can this happen? I'm really interested in what sort of mechanism could cause it. Insperatum (talk) 07:43, 17 September 2009 (UTC)

I bet her doctor could give her a much better answer than we can. It could be an eye-based migraine, it could be a coincidence, it could also be a serious problem. Seriously, ask a doctor. Matt Deres (talk) 15:48, 17 September 2009 (UTC)

Gravity at the center of a body

This is probably a classic question but if I were to drill a hypothetical hole through the diameter of a large object (like the Earth) and drop a body of mass through it, what would happen as the mass approached the center? Since gravity is acting on all angles of the mass, would it remain suspended at the center? -- penubag  (talk) 08:18, 17 September 2009 (UTC)

In the classroom case (nice, straight hole, spherical cow in a vacuum, no rotation of the planet or hole drilled right along the rotation axis), the body would accelerate exactly up to the mid point (although the acceleration would slow down smoothly), and then continue through the middle, still moving but decelerating, until it came to rest exactly on the other side of the Earth. If unstopped, it would then fall back and oscillate forever (in Newtonian physics) or for very very long (in General relativity). If you allow for air, it would fall very slowly and either soon be crushed, or come to rest at the point where the density of the atmosphere equals the density of the object. --Stephan Schulz (talk) 08:45, 17 September 2009 (UTC)

see http://en.wikipedia.org/wiki/Wikipedia:Reference_desk/Archives/Science/2009_September_11#Path_through_Earth it oscillates. 87.102.94.154 (talk) 09:04, 17 September 2009 (UTC)

Assuming that the volume of the hole << volume of the planet, you have a Harmonic oscillator. Elocute (talk) 09:49, 17 September 2009 (UTC)

I don't think you even need to make that first assumption.87.102.94.154 (talk) 10:34, 17 September 2009 (UTC)

He does plus that the density is uniform. Anyway even with that it won't be exactly harmonic as time will go slower right at the very centre even though there is no gravitational accceleration there due to gravitational time dilation never mind its greater speed there. Now that's really idealizing things. Dmcq (talk) 13:39, 17 September 2009 (UTC)

What happens if there is a large hole then?83.100.251.196 (talk) 17:24, 17 September 2009 (UTC)

If there was a big hole in the centre of the earth you'd be weightless there, unlike some wierd sects or sci fi about walking about on the inside. You feel zero gravity inside a uniform spherical shell. Dmcq (talk) 17:47, 17 September 2009 (UTC)

You're weightless inside a (big or) small hole at the centre (not anywhere inside it) - what is the difference between a large and small hole through the earth when something is dropped into it? (The hole is cylindrical - they were going to drop something down it..)83.100.251.196 (talk) 18:19, 17 September 2009 (UTC)

You are weightless everywhere inside a shell of uniform density. This is somewhat surprising, but a well-known fact. Intuitively, the larger forces from closer matter on one side side are balanced by the larger mass of the matter on the other side of the sphere. As for the second part of your question: The problem with a large hole is that a harmonic oscillator is not just any oscillator, but an oscillator where the acceleration is proportional to the distance of the oscillating mass from the zero point. This is true for a mass falling through the earth - the gravity of the outer shell cancels, so the effective mass goes down with the third power of the radius. Since gravity is an 1/r² force, two of those powers cancel, leaving a linear dependency on the radius. If you consider a big hole, what you get in the end is more or less a doughnut shape, and the relation does not work out anymore. --Stephan Schulz (talk) 18:31, 17 September 2009 (UTC)

Can I assume that you are talking about spherical holes, and me about cylindrical holes.. I thought the idea was that the earth was being treated as a Shell_theorem#Solid_spheres, and that there was a cylindrical hole (large or small) - in this case it seems likely (without doing the maths) that the net force will only be zero when the particle is inside an 'empty sphere' ie when the particle is inside a sphere or radius r (where r is also the radius of the cylinder).. In the big hole case it is interesting because whilst inside the zero force void the speed will be constant - but when leaving that space it will experience a force (towards the centre) again.

Therefor I think that even with a big hole - the particle will still oscillate.83.100.251.196 (talk) 19:02, 17 September 2009 (UTC)

Oh yes, it will oscillate. But it will not be a harmonic oscillation. It's only harmonic if the diameter of the (cylindrical) hole is negligible. --Stephan Schulz (talk) 19:26, 17 September 2009 (UTC)

For the record the shape of the hole is irrelevant, if it is large enough to cause non-negligible deviations in the gravitational field of the large body in question from the gravitational field of a solid sphere, at any point along the particles path, then the oscillation will no longer be harmonic. My earlier statement was made with the same interpretation that you hold, one of a solid sphere with a cylindrical channel cut through it. Elocute (talk) 01:56, 18 September 2009 (UTC)

Very sorry - I totally failed to notice that you wrote "harmonic" - I just saw the oscillator part. Hence my stupid questions. Sorry again.83.100.251.196 (talk) 11:09, 18 September 2009 (UTC)

Don't be sorry. I just wanted to clarify in case there had been a misunderstanding. Elocute (talk) 20:36, 20 September 2009 (UTC)

I need to ask a question on the maths desk arising from this, please feel free to look at it and answer if you can, thanks.83.100.251.196 (talk) 19:08, 17 September 2009 (UTC)

Thanks for the replies, but if there were air resistance what would end up happening? -- penubag  (talk) 08:08, 19 September 2009 (UTC)

See above. Any kind of permanent resistance will dampen the oscillation. If you assume the air pressure hat would "naturally" form in such a whole, the air would soon become so dense that it would crush and/or float your oscillating body. --Stephan Schulz (talk) 08:30, 19 September 2009 (UTC)

Finding a vein: legs, arms and the jugular

At the execution attempt of Romell Broom, why did they try to find for two hours - without success - a vein in the legs or arms? Isn't it much easier to use the jugular?--Quest09 (talk) 09:12, 17 September 2009 (UTC)

It's (nearly) always possible for someone with adequate medical training to obtain venous access. But it's likely that [1] since most physicians consider it unethical to take part in a medical capacity in an execution, those trying to gain IV access had little experience doing so, and that [2] they would have had training only in accessing peripheral veins rather than central ones. And it's likely that [3] the Ohio state execution protocol makes no allowance for use of the jugular vein, and that the executioners would not be allowed to improvise in that way. - Nunh-huh 09:26, 17 September 2009 (UTC)

Anti - Perspirant causes Cancer

A while ago there was a mail doing the rounds claiming that the use of anti-perspirants could be a major factor in womans breast cancer as wel as other cancers of the glands. It was based upon the "Fact" that the armpit and the area behind the knees are the major areas where toxins are excreted through the sweat glands. This process is then infuanced by the use of anti-persperants which prevents this cleansing action, toxins build up and causes cancers. Specificaly in the chest/breast area !

How true is this and ho save is the use of anti-perspirants?

Regards ~~

Snopes flags this as "undetermined"--Shantavira|^{feed me} 11:46, 17 September 2009 (UTC)

If the word "toxins" is involved, then it is likely bullshit. No actual scientific study in a peer-reviewed journal would use such terminology. --Jayron32 12:09, 17 September 2009 (UTC)

To be fair, 'toxins' is the sort of word used by 'science reporters' when summarizing and relaying the results of genuine scientific papers (which those reporters may or may not fully understand themselves) to the lay public. That said, the links provided by Shantavira to Snopes and to Nanonic to our own articles contain the relevant references. My personal take on it is that a) the body doesn't use sweat to get rid of any significant amount of cytotoxic material; b) the lymph nodes don't drain fluid (toxic or otherwise) through the sweat glands; and c) tumours of the breast virtually never start in the lymph nodes, but rather originate in other tissues and then metastasize (migrate) to the lymphatic system. It's a creative hypothesis, but one unsupported by convincing evidence. TenOfAllTrades(talk) 12:40, 17 September 2009 (UTC)

See Deodorant#Aluminium neurotoxicity and Deodorant#Cancer. Nanonic (talk) 12:21, 17 September 2009 (UTC)

Safety of soy protein extraction using hexane

There are alarming claims on the Internet about the safety of using hexane to extract soy protein. Based on the evidence available and what we know about the chemical, what would be a scientifically-sound risk assessment of the practice?

I'm not aware of the specific claims, buy vegetable oil has been extracted using hexane for many years, - if there were any ill effects it should have shown up by now.

Also hexane is used to extract fat and oil from soy, not the protein.

I can't find any realistic claims of dangers amongst all the scaremongering - most of the sources appear to be based on cornucopia.com which found hexane at 21ppm. (And this bears all the hallmarks of scaremongering by an interested party to easily worried organic food people.)

If 21ppm was remotely harmful the FDA or similar would have acted ages ago. I hope.83.100.251.196 (talk) 17:22, 17 September 2009 (UTC)

See this [4] a recommended limit of 50ppm, and no adverse effects reported at 500ppm long term exposure. However I think that is for atmospheric exposure, though 83.100.251.196 (talk) 18:39, 17 September 2009 (UTC)

[5] gives some FDA standards for hexane for food residues - typically requiring less than 25ppm.83.100.251.196 (talk) 18:46, 17 September 2009 (UTC)

The same source states that hexane is GRAS Generally recognized as safe for these processes. So at current levels of understanding I would assume that there is no particular danger from soy bean.83.100.251.196 (talk) 18:48, 17 September 2009 (UTC)

A greater danger comes to those that work with hexane.83.100.251.196 (talk) 18:53, 17 September 2009 (UTC)

(I don't know if alternatives exist - possibly supercritical carbon dioxide extraction might work, and work eliminate these problems.)

The main problem here is that practically all the population of many countries is exposed to hexane processed foods (vegetable oils excluding cold pressed, margarine, also animal feed) - if there was a general effect such as mental retardation in adults, it wouldn't be easy to show, since practically everyone would have it...83.100.251.196 (talk) 19:53, 17 September 2009 (UTC)

Pure Hexane itself is probably pretty safe, but if it is contaminated with benzene or other substances, it could be hazardous. Graeme Bartlett (talk) 06:15, 18 September 2009 (UTC)

Hexane#Toxicity has some good info. Aligns with what I've read in chemical-safety publications and chats with other chemists. DMacks (talk) 06:44, 18 September 2009 (UTC)

Why not extract with heptane to avoid any chronic side-effects? Anyway, solvent extraction is done all the time -- for your prescription drugs, your vitamins, for the phosphoric acid they use to acidify your coke, etc. Hexane has a lower boiling point than water or ethanol, so what you do next is prolly extract into ethanol and then distill the hexane off. I imagine in the food industry has pretty high standards. John Riemann Soong (talk) 13:45, 18 September 2009 (UTC)

They usually just evaporate the hexane extract leaving the oil behind, a vacuum will also be applied to aid the process. No ethanol in vegetable oil extraction not entirely true - may be used - but in a different process. (This is a simplification) It's different for stuff like flavourings etc. were ethanol is used.

There's an example here using hexane and ethanol for extraction [6], ethanol for oil has been tried - but basically doesn't work [7] (my synopsis) - however getting more complicated it may work [8] (here they 'precipitate' the oil out of the extract as micelles. there are issues with ethanol extracting stuff that hexane doesn't..)83.100.251.196 (talk)

This is all off-topic, and simplified - search the web for "vegetable oil ethanol extraction" or similar, for the full picture.83.100.251.196 (talk) 15:40, 18 September 2009 (UTC)

Good question - actually I've just tagged hexane with "citation needed" as regards heptane as a replacement - it's not clear to me that heptane would actually be any better. Specifically I suspect the reason why heptane may appear a better choice on the surface is that it is relatively unused - in contrast to hexane which has vast amounts of literature relating to its toxicity - it could turn out that heptane is no better - but simply that toxicity data does not yet exist.83.100.251.196 (talk) 14:13, 18 September 2009 (UTC)

eg http://www.cdc.gov/niosh/pel88/142-82.html

the ACGIH concluded that heptane was more acutely toxic than hexane. The ACGIH therefore recommended limits for heptane that are somewhat lower than the limits for the hexane isomers."

chronic toxicity not mentioned.

also:

..because NIOSH believes that "it would be incorrect to conclude that the neurotoxic properties ascribed to n-hexane are unique to this compound [n-hexane]. Other alkanes or related chemicals [such as heptane] that are ultimately metabolized to gamma diketone may have similar toxicity

OSHA is the organisation that thinks hexane is uniquely toxic (or did-they may have changed there minds) - there's more evidence for exactly the same sort of toxic effects from heptane as found from hexane occuring at basically the same concentrations.

I think I will delete the claim at hexane.83.100.251.196

What about branched isomers? John Riemann Soong (talk) 16:32, 18 September 2009 (UTC)

isohexane [9] 83.100.251.196 (talk) 17:39, 18 September 2009 (UTC)

Would it still be metabolised into gamma-diketone? John Riemann Soong (talk) 20:12, 18 September 2009 (UTC)

It can't be since the 2 carbon (of 2,4 diketone) is tertiary. (assuming isohexane is 2methyl pentane)

For the 'isohexane' mixture of isomers only 3methylpentane can do this without rearrangement. I don't know what exactly will happen.83.100.251.196 (talk) 21:43, 18 September 2009 (UTC)

As far as I know, most alkanes (hexane, heptane, etc.) are pretty much biologically inert as far as metabolism is concerned, and whatever toxicity they might have is caused by their physical properties (hydrophobic properties, vapor pressure, etc.), mainly at pretty significant doses. So we don't really have to worry about traces of hexane in the food we eat. A bigger danger (as 83.100 pointed out) is to the workers that work with hexane -- and that danger mostly comes from hexane's extremely high flammability. :-) FWiW 98.234.126.251 (talk) 02:40, 19 September 2009 (UTC)

Unknown beetle

Hi!

During a travel in Minneapolis, I saw the beetle on the picture. The problem is, that I don't know which beetle it is. Can someone help me?

Regards, Tanzania (talk) 14:13, 17 September 2009 (UTC)

Looks like a Three-lined potato beetle, Lema trilinea. --Sean 18:09, 17 September 2009 (UTC)

I see they've renamed it to Lema daturaphila. There are lots of beautiful pictures of them online. --Sean 18:15, 17 September 2009 (UTC)

Or Lema trivittata. It's pure hubris for a non-expert like me to even be guessing on exact species; what's that line about God and beetles? --Sean 18:33, 17 September 2009 (UTC)

It does look as one of the pictures you linked to. There are no article about the specie or the genus on english wikipedia, am I right? Tanzania (talk) 19:47, 17 September 2009 (UTC)

But all the species you wrote look the same... Are they different? Tanzania (talk) 19:56, 17 September 2009 (UTC)

All three names are for the same species, here's even more images [10]

Though this [11] suggests there are sub-species -- 83.100.251.196

Thank you! Think I'd better create articles about the subfamilies etc..

Tanzania (talk) 20:30, 17 September 2009 (UTC)

Good idea (but I'd recommend only covering down to the species level - subspecies can be dealt with in the main species article !83.100.251.196 (talk) 20:41, 17 September 2009 (UTC)

(EC) Presumably they are different in some way, or they would all be the same species. I really don't know anything about them, I just googled "beetle gold black stripes red thorax" and saw them on Google Image Search. Before that I tried some of the bug ID sites, but wasn't successful (none of them are very good, that I've found). --Sean 20:34, 17 September 2009 (UTC)

on gas cylinders

hi,

when we ignite a gas stove, we obtain a flame. But there is no possibility of the tube connecting the stove and the cylinder, catching fire thereby leading to the explotion of the cylinder. Why is it so? What is the mechanism behind it?

Combustion requires oxygen (among other things). With a pressurized gas tank, though, only gas is flowing through the tube and only toward the outside air. Thus, there's no oxygen in the tube via the tank nor is there oxygen in the tube via atmospheric mixing. Combustion, therefore, cannot happen. — Lomn 15:21, 17 September 2009 (UTC)

I have an uncle who almost died from a gas explosion like this. Off course, like Lomn said, the stove can't ignite it, but an open fireplace ignited it and the pipe burst into flames and he had to leg it.--Patton123 (talk) 17:23, 17 September 2009 (UTC)

pervaginal examination

• This question has been removed as it may be a request for medical advice. Wikipedia does not give medical advice because there is no guarantee that our advice would be accurate or relate to you and your symptoms. We simply cannot be an alternative to visiting the appropriate health professional, so we implore you to try them instead. If this is not a request for medical advice, please explain what you meant to ask, either here or at the talk page discussion (if a link was provided).

Please see your medical professional. Wikipedia is not able to answer your request for medical advice. Nimur (talk) 20:39, 17 September 2009 (UTC)

Do chimps sit?

You know how humans sit, as in knees & butt making 2 right angles. Do you ever see any other animals doing that?

Many apes (chimps gorillas whatever) will 'sit on their haunches' (butt to ankle) but I've rarely seen them sitting on a tree stump etc in a 'right angled' pose.

So have we evolved to sit, or is sitting a handy convenience that for some reason no other animal takes advantage of?

Discuss... --Mortice (talk) 21:52, 17 September 2009 (UTC)

I don't know the answer, but one note that I think has to be made is that we have not evolved from chimps, but rather both we and chimps have a common ancestor. I realize that you didn't say that we evolved from chimps, but a reader might mistakenly get that impression. Bus stop (talk) 22:04, 17 September 2009 (UTC)

Well, all of these are pretty fun. The closest I saw was this one, which is essentially what you're looking for, although it's a barbary ape, i.e. not actually an ape. This, also, is... interesting. I'm no expert on ape movement, but I did just see a bunch at the zoo. You'll notice that (Gorillas, anyway) swing their legs when differently than we do, indicating a different comfort range of motion. Also, don't forget, we have chairs. They have rocks and logs. Some of them are okay, but sitting on a flat rock with your legs at right angles? The backs of your upper legs can really start to hurt and have decreased blood flow, especially if you've got long/heavy legs, as a number of monkeys and apes do (relative to us). ~ Amory (user • talk • contribs) 22:35, 17 September 2009 (UTC)

Thanks for the pics - the majority of those are what I refer to as 'sitting on haunches', and you picked out a few where they're sitting with legs splayed. Perhaps it's really not in their anatomy to 'sit' as we do - and by 'their' do I really mean all creatures other than Man? People seem to 'sit' very naturally (although I've seen some ethnicities are more likely to 'sit on haunches' than others). Is there anything in the evolutionary path which brings us to it, or an evolutionary step-change, or just a more modern social trend to sitting? --Mortice (talk) 18:08, 18 September 2009 (UTC)

Just in case it isn't obvious... people find sitting comfortable due in large part to them having butts to sit on, as in literal buttocks that cushion your tail bone. While all primates have the same basic musculature there, they lack that fleshiness that we take for granted. A chimp that tried to sit as I am now (in a chair) would have all his weight focused on his tail bone in a distinctly uncomfortable way. Matt Deres (talk) 16:39, 21 September 2009 (UTC)

Global warming

What makes us think it is human caused? How much greenhouse gas do human produce and how much is produced by natural processes? The charts I have seen only show temperatures slightly higher than the medieval warm period. Is this true? How do we know it isn't the Sun's absense of sun spots? Sorry just don't know much about it.--92.251.140.93 (talk) 22:30, 17 September 2009 (UTC)

The Sun's low activity only started in the last year or so, global warming pre-dates it. Temperatures aren't increasing to higher levels than they have been in the past, but they are doing so faster. --Tango (talk) 22:37, 17 September 2009 (UTC)

Read attribution of global warming and our main article on global warming. Essentially, there is no doubt that the increase in GHGs is man-made - it's shown by simple mass balance computations and confirmed by changes in the ratio of carbon isotopes - see Suess effect. Yes, our contribution is small compared to the overall flows in the carbon cycle, but it is actually larger than the overall increase (some natural carbon sinks become temporarily more efficient with increased atmospheric CO2). It's the difference between a circulation pump and filling the pool. We also understand the basic effect of GHG's from first principles, and there is no serious doubt about that - if the Greenhouse effect did not work, we would all freeze to death. What is more tricky is the modeling of second-order effects and feedbacks. However, even there we have good models that allow us to make educated predictions, and that are supported by a large consensus (see Scientific opinion on climate change). --Stephan Schulz (talk) 22:59, 17 September 2009 (UTC)

The combined plot above (showing records back to a nominal 500 million years ago) should be examined with caution. Particularly worth noting is that the time axis is a logarithmic scale; the apparently gentle sloping increase of the last few decades would be a vertical line if it occurred nearly anywhere else on the graph. TenOfAllTrades(talk) 15:55, 18 September 2009 (UTC)

The most convincing evidence for the layperson is to examine a graph of temperature over the past few hundred thousand years versus the amount of CO2 in the atmosphere. The graphs are essentially identical. This essentially proves that the fluctuations we're seeing are directly related to CO2 in the atmosphere. Now - mentally zoom into that graph and look at just the last 10,000 years since human civilisation has been around...the stuff before that doesn't matter because we weren't around to care about it. Now you can see that the levels have been increasing steadily since humans became civilised - but even on that scale, the numbers are kinda similar to the worst spikes from before humans were around. The telling fact is that this graph has an arrow pointing to TODAY's CO2 levels...which are essentially "off the chart". There is no line on the graph showing that because it's happened on such a short timescale. So - now we know that (a) global temperatures track CO2 in the atmosphere very closely...and (b) that the levels have gone through the roof over the last 100 or so year. So now we have to figure out what's causing that abnormal increase in CO2 levels. Well, we know how much we're producing - we can calculate it from fossil fuel consumption - and lo and behold - the amount of the crazily abnormal increase is a really close match for the amount we're pumping into the air. Conclusion: It's all our fault. I honestly can't see a way out of that logic. SteveBaker (talk) 17:55, 18 September 2009 (UTC)

Actually, this graph is one of the things that seems to *debunk* the CO2-causes-temperature argument. I'd like to see the actual numbers, but in this graph it appears that changes in temperature *preceed* changes in CO2. Wikiant (talk) 18:02, 18 September 2009 (UTC)

I think the graph's axes are too small to show that accurately...and you have to look at the START of the temperature increase - not the peak. Look at the very start of the 350,000 and 250,000 year increases - and in both cases, you see a rather modest (blue) CO2 increase just before a huge (red) temperature increase - which the CO2 level then tracks. That suggests that the Greenhouse effect is the trigger for the temperature rise - which (once it's already shooting up) pulls the CO2 level up with it. That suggests a vicious feedback effect...which is a very possible (and vary scary) thing. SteveBaker (talk) 18:23, 18 September 2009 (UTC)

See [12] and the accompanying discussion. Dragons flight (talk) 05:02, 19 September 2009 (UTC)

There are tests one can do for (granger) causality, but again one needs the data. What gives me pause is that, every time I hear someone point out an inconsistency in the CO2-warming argument, what I hear back is not a refutation on the grounds of the argument, but an increase in the complexity of the argument. In the end, the CO2-warming argument begins to sound like a non-falsifiable hypothesis. Wikiant (talk) 18:31, 18 September 2009 (UTC)

Those tests won't be able to tease out a graph like the one above because, as steve pointed out, the is a possibility of a positive feedback effect. causality tests can't tell which one comes first, the chiken or the egg? The point is that it doesn't matter whether the CO2 is the chiken or the egg. Either way, more of one leads to more of the other. More CO2 leads to higher temperatures. Dauto (talk) 19:09, 18 September 2009 (UTC)

You are incorrect. Granger causality tests can tease out (granger) causality in the presence of positive feedback. Wikiant (talk) 20:43, 18 September 2009 (UTC)

"Despite its name, Granger causality does not imply true causality." But that's a bit besides the point. While the correlations are striking (and useful in understanding the effects of feedback), the basic "CO2 causes warming" argument is not a statistical one, but is based on simple and uncontroversial spectrographic properties of CO2. See below. --Stephan Schulz (talk) 20:58, 18 September 2009 (UTC)

Hmmm. What "inconsistencies" in the basic arguments have you heard? CO2 is nearly transparent in the visible light. The sun, at 6000K, emits mostly in the visible light. That light hits the earth and warms it. The earth is around 15K°C or so, and emits mostly in the infrared. CO2 absorbs very well in the infrared, so the infrared cannot escape directly into space, but heats up the atmosphere. If there is more CO2, this effect becomes stronger. The warmer atmosphere will emit more energy from higher altitudes (where there is less chance of interaction with GHG molecules), so that eventually a new equilibrium is reached, but at a higher temperature. That's the basic mechanism that has been understood for much longer than we can reliably measure either the temperature or the atmospheric CO2 content. See Svante Arrhenius, who predicted the effect in 1906. --Stephan Schulz (talk) 20:54, 18 September 2009 (UTC)

The Earth is substantially hotter than that. Algebraist 21:33, 18 September 2009 (UTC)

Swedish scientist/Scot scientist - the difference is only 273.15 degrees ;-). --Stephan Schulz (talk) 21:49, 18 September 2009 (UTC)

This is an example of my earlier point that it seems like the CO2-warming hypothesis is non-falsifiable. (1) "A" presents the graph as evidence that CO2 causes temperature; (2) "B" points out that changes in temperature predate changes in CO2; (3) "A" says that what's going on is a feedback and it is not possible to tease out which causes which; (4) "B" says, no there are tests that help us get at that; (5) "A" says, forget the tests, we know that... For each point that "B" raises, "A" shifts the grounds of the argument. It feels all too similar to the evolutionist-creationist debate. Wikiant (talk) 21:36, 18 September 2009 (UTC)

Oh, it's quite similar to the evolution/creation debate indeed. In both cases there is a large, coherent theory, supported by massive evidence, a near unanimous consensus among scientists, and support by all major scientific organizations. In both cases the theories are quite detailed, with a stable framework but ongoing refinements, and not fully understood by the general population. And in both cases an organized campaign uses the complexity of the issue to build straw men, misrepresent the science, and repeat long refuted arguments ad nauseam. And, btw, I never offered these graphs as evidence - exactly because their interpretation is not trivial, and they are not needed for the basic argument. Your "A" is several different As. --Stephan Schulz (talk) 22:02, 18 September 2009 (UTC)

Despite of what you said, your test doesn't work here because there is a feedback is the correct answer for your point. Your test might be able to tell us that the temperature change predates the CO2 but is a case of positive feedback that does not matter. It does not matter which one comes first because either one of them can get the feedback cycle started. Dauto (talk) 04:39, 19 September 2009 (UTC)

For those that didn't read Dragon flight's post, see What does the lag of CO2 behind temperature in ice cores tell us about global warming? and The lag between temperature and CO2. (Gore's got it right.) -Atmoz (talk) 05:07, 19 September 2009 (UTC)

Has anyone noticed that in the first graph (which is the only one with sufficient detail to show temperature variation year by year), the annual average has actually been going down for the past 4 years? Now that might be just a statistical blip, but then again, it might be the start of a cooling trend, which would contradict the "greenhouse effect" hypothesis. FWiW 98.234.126.251 (talk) 02:51, 19 September 2009 (UTC)

Greenhouse effect has been known about for a long time IIRC from secondary school chemistry class, and is the reason the earth isn't absolutely feezing, it can easily be proven by filling a bottle with CO2 and another one with O2 and putting a thermometre into each one (At least I think it was a bottle...can't quite remember) and the CO2 one turned out to heat up faster than the toehr one when left in the Sun. It's the earth getting hotter because of humans you're talking about, not hte greenhosue effect.92.251.201.218 (talk) 09:13, 19 September 2009 (UTC)

Let's say you found the Earth control panel. Do you think it's wise to say "Hmm, maybe I'll move this 40%"? Sagittarian Milky Way (talk) 20:54, 19 September 2009 (UTC)

...and then remove the knob so you can't turn it back down again for a few thousand years. SteveBaker (talk) 00:07, 20 September 2009 (UTC)

Exactly.

And the rate of rise is not even decreasing.. What happens when China and India quadruples the industrialized population? Sagittarian Milky Way (talk) Sagittarian Milky Way (talk) 00:58, 20 September 2009 (UTC)

You're evading my question: How would you explain the cooling trend seen for the past 4 years if it continues? (and yes, there has been a cooling trend for the past 4 years, if you look closely at the graph). Sagittarian, in particular, I don't know if you choose to ignore this, or if you just didn't see it on the graph, but your claim that "the rate of rise is not even decreasing" contradicts this part of the graph. 98.234.126.251 (talk) 04:52, 21 September 2009 (UTC)

You misread SagMW - he was talking about atmospheric CO2, not temperature. As for the "4 year cooling" meme, you cannot compute a remotely reliable trend from 4 datapoints, and the plot does not even show a 4 year continuous decline in temperature - if you look at either the plot or the raw data, temperature was at an all-time high in 2005, fell to 2006, rose a bit in 2007, and fell back in 2008. All of 2005, 2006 and 2007 were warmer than 2004. We are experiencing a long-term secular increase in temperature, overlaid with short-term fluctuations. --Stephan Schulz (talk) 09:06, 21 September 2009 (UTC)

natural or something else?

Is a blind canyon related to weather or nature-made structures?69.203.157.50 (talk) 23:26, 17 September 2009 (UTC)

Our article on Canyons says nothing about "blind" ones. An article on flying in mountains describes flying into a blind canyon, and the need to be able to turn and fly back out. Presumably a canyou might be when a river runs through elevated terrain so that the heights on either side rise up. If a watercourse flows down a mountain, then the pilot might fly in at one altitude, and be unable to climb over the terrain at the point where the watercourse enters the canyou. In western movies, they often spoke of "box canyons," which let you ride in, but you could not ride out the far end, because it rose up. It is something with just one reasonable way in and out. (Good spot for an ambush). The term "blind canyon" is sometimes used as a metaphor for thought processes or organizational processes which lead to a dead end. It is a common place name. I would vote for "nature built" unless it is a metaphor. It is related to weather only in that watercourses carve out canyons over eons and precipitation, a part of weather, makes the river flow. On places with little or no rain, like Mars, wind and sand might be able to carve out canyons over a longer time span. Edison (talk) 04:22, 18 September 2009 (UTC)

Is "blind canyon" a specific place -can you link to it. I would expect there might be more than one...83.100.251.196 (talk) 14:10, 18 September 2009 (UTC)

"Blind canyon" is mentioned in the article about Lance Reventlow and an article about one other person.69.203.157.50 (talk) 15:29, 18 September 2009 (UTC)

In that context "blind canyon" is an aeronautical term, and not a geological one.83.100.251.196 (talk) 16:50, 18 September 2009 (UTC)

Weather might play a part, but I would think that it is called a blind canyon due to visibility being obstructed by the mostly vertical walls of the canyon. Also perhaps radio contact is affected by flying in a canyon. Bus stop (talk) 17:19, 18 September 2009 (UTC)

A blind/box canyon is one you can ride or walk into, but the sides are too steep to be climbed easily, and when you reach the end, it is also too steep to climb. As I said, it would typically be a geological feature carved out over thousands or millions of yearasa by the flow of water from the high end. The watercourse might have dried up or only flow intermittently.There are many such places, as shown by a Google search Edison (talk) 19:49, 18 September 2009 (UTC)