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July 14

Electonic ab belts/abdominators/whatever they're called...

(I'm sure that WP has an article on these - but I'll be damned if I can find it) So, those battery-powered ab belts that supposedly use electricity to rhythmically contract the muscles of the abdomen (or the muscles of whichever body part you've attached it to) and promote muscle growth without actually having to exercise and turn flabby guy --> ripped guy - quackery or effective way? I suspect that I already know the answer to this (I bought one on a whim years ago and it didn't really do much except make my abs twitch mildly for the couple of hours that the battery lasted - and the couple of hours that the next battery lasted). Is there any real science behind these devices? --Kurt Shaped Box (talk) 01:05, 14 July 2009 (UTC)[reply]

Is Electrical muscle stimulation what you're looking for? Intelligentsium 01:24, 14 July 2009 (UTC)[reply]

Yeah, pretty much. Thanks. Redirect created there from Ab belt... --Kurt Shaped Box (talk) 01:54, 14 July 2009 (UTC)[reply]

I think this is absolute BS, they're just trying to steal your money. You want strong abs, do lots of crunches (and it won't cost you a penny). 76.21.37.87 (talk) 01:30, 14 July 2009 (UTC)[reply]

Does anything help unjoin PVC?

I have a custom shaped PVC part for electrolysis. A part inside needs fixing, the only way I can get tools close enough is to remove the PVC pipe that is bonded to it. Does anyone know of anything that helps unbond PVC pipes. It looks like the bonding material is clear light yellow substance. I don't know if it is PVC cement or something else, but it looks bonded. My current method is to slowly cut slits into the PVC pipe and chisel it out.--155.144.40.31 (talk) 01:16, 14 July 2009 (UTC)[reply]

Just heat it up with a heatgun and stick a sharp edge into it. The glue will come off quite cleanly that way. --antilived^{T | C | G} 01:27, 14 July 2009 (UTC)[reply]

Thanks I heated it up and basically peeled it off.

The stuff I use (which is for plumbers - and is a bright purple color) melts the PVC - the glue itself hardly matters because once it's done it's stuff, the two pieces of PVC have become one piece - and nothing will get it apart. Personally - I'd look for longer/thinner tools to try to fix the problem without too much destruction...but without a lot more information, it's hard to suggest what tools might help. SteveBaker (talk) 01:42, 14 July 2009 (UTC)[reply]

The glue does matter, as it fills in the spots where the melted PVC didn't touch. Interesting fact: the primer is not inherently purple, but colored that way so that building inspectors can verify that it was used. --Sean 13:27, 14 July 2009 (UTC)[reply]

When you heat up that stiff PVC pipe with a heat gun it becomes soft and flexible like rubber. It is amazing! Graeme Bartlett (talk) 06:13, 15 July 2009 (UTC)[reply]

Possibility of a strabismus drug?

In theory, could a drug be developed that would treat the neurological aspects of strabismus with amblyopia (i.e. allow the brain to properly merge images from both eyes)? Neon Merlin 01:28, 14 July 2009 (UTC)[reply]

It seems unlikely, because problems of this sort are generally due to "miswiring" that develops over time, and any treatment requires time and experience to correct the miswiring. It seems entirely possible, though, that a drug that increases the plasticity of neural circuits could make physical therapies more effective. Looie496 (talk) 03:35, 14 July 2009 (UTC)[reply]

distance light travels per cycle

How far does light travel in one transition cycle of the magnetic phase and the electrostatic phase? -- Taxa (talk) 02:29, 14 July 2009 (UTC)[reply]

This is precisely what the wavelength is. So the answer depends on the wavelength of the light. For visible light, the answer is between about 400 and 700 nanometers. But it could be anything. Some radio waves, for example, are several meters long. —Dominus (talk) 02:51, 14 July 2009 (UTC)[reply]

The answer above must be correct, eventhough the question isn't since light doesn't have an alternation between a magnetic phase and a electrostatic phase (For one thing, the word static means "no change" so it wouldn't fit here). Both the electric and the magnetic fields oscillate simultaneously in phase (that is, they reach their maximum amplitude simultaneously). Dauto (talk) 11:50, 14 July 2009 (UTC)[reply]

Gaviotas sleeve pump

There is a kind of manual water pump, invented at the "appropriate technology" Columbian town of Gaviotas which they call a "sleeve pump" (Bomba de Camisa). Most of the descriptions of it I can find are taken from Alan Weisman's book Gaviotas, which includes a diagram. A reasonable excerpt describing it, with the diagram can be found here (although a higher resolution version of the diagram can be found at this Google Books version). Also, there is an installation manual (in Spanish, scanned into PowerPoint) here.

I have not been able to make out how the thing works. The diagram shows an outer sleeve being moved, but nothing else. No description of what air or water chamber is pressurized, exhausted, or lifted; just water magically flowing up in the right illustration. Can anyone explain what's supposedly going on? Thanks. -R. S. Shaw (talk) 02:45, 14 July 2009 (UTC)[reply]

From what I've read in the text on the preceding few pages, it appears to me that the sleeve is rigidly attached to the perforated casing it encloses, which therefore moves up and down with the sleeve in relation to the immovable piston inside the casing, thus creating the pressure that pumps the water. Looks to me like the diagram is wrong. FWIW 76.21.37.87 (talk) 08:44, 14 July 2009 (UTC)[reply]

What is this plant?

This weed grows all over Philadelphia. The leaves vary greatly in size, and sometimes span 30 cm or more. It is usually a low shrub. In the summer, it bears hard spherical fruits about 2cm in diameter. What is it?

Thanks. —Dominus (talk) 02:47, 14 July 2009 (UTC)[reply]

Looks like a fig tree to me. Probably s.th. like an Alma or Celeste. The fact that it gets too cold in winter might account for the shrub size. 71.236.26.74 (talk) 03:47, 14 July 2009 (UTC)[reply]

I don't think it's a fig. I believe what you have there is Paper Mulberry. Our article doesn't seem to picture the lobate leaf forms of the immature plants, but compare the images here (particularly the bottom one, just above the map). Deor (talk) 16:13, 14 July 2009 (UTC)[reply]

Thanks. So far, I like the paper mulberry theory much better than the fig theory. This plant does indeed have a variety of leaf forms, with only the larger leaves being lobate. I will try to open up one of the fruits and see if it looks like a fig. —Dominus (talk) 17:22, 14 July 2009 (UTC)[reply]

Now that I've done some more reading and seen some more pictures, I am sure that this is correct. Thank you very much. 17:27, 14 July 2009 (UTC)

Wellness and the Wellness Wheel

I've been thinking of starting an article on the concept of the "Wellness Wheel" as per these temporary online sources:

but I'm unsure whether it is already covered somewhere else in Wikipedia or if it should be a section in the Health article or Wellness (alternative medicine)? Is the term "wellness" used in this context a separate definition apart from alternative medicine? Is this a notable enough topic to write about? From what I know of the Wellness Wheel concept is that it's used in many drug and alcohol rehab centers as a harm reduction alternative to the 12-step program (see google books) yet I see mention of this nowhere. So I'm unsure if I should start the article going of those web refs or just update Health or Harm reduction or to include this ?new? concept. Better yet, if someone more educated in the field than I could take the lead and start me off with a short stub that would be great. -- œ ^™ 03:04, 14 July 2009 (UTC)[reply]

When is it too cold for Mosquitos?

My friend and I disagree about whether I'll cause us to have mosquito bites if I leave the window open with lights on inside tonight. Thing is it's quite chilly outside at the moment! My understanding is that under such conditions mosquitos would not be a nuissqnce. So who's right? Do mosquitos not roam on very cold nights? (even if they do yesterday and tomorrow, when it isn't really chilly)? Thanks! —Preceding unsigned comment added by 82.234.207.120 (talk) 03:44, 14 July 2009 (UTC)[reply]

minimum temp for mosquito growth is 8-10°C [1] so it needs to be that cold for the mosquitoes to stop developing. Also the insects survive the winter via hibernation or as eggs[2] so they won't bother you in the winter or anywhere where it is less than 8 C.--Lenticel ^(talk) 04:02, 14 July 2009 (UTC)[reply]

ah, but I was talking about an exceptionally cold night in otherwise mosquito plagued season... So my question is not about breeding, but whether they will bite me on a cold night (where the previous or next night is a definite yes)... —Preceding unsigned comment added by 82.234.207.120 (talk) 04:23, 14 July 2009 (UTC)[reply]

As I said earlier, you have to be at winter temperatures (subzero) for the adults to to hibernate or die after laying their eggs. --Lenticel ^(talk) 04:42, 14 July 2009 (UTC)[reply]

I've read somewhere that the temperature below which mosquito activity declines dramatically is around 13°C. ~A H 1^(TCU) 09:07, 14 July 2009 (UTC)[reply]

thanks - you actually answered my question. And it was below 13degrees. 82.234.207.120 (talk) 15:02, 14 July 2009 (UTC)[reply]

HUAUZONTLE - red or green or both ???

researching Huauzontle and trying to ascertain different varieties..

on website "seeds of change" the picture is red and on gourmet sleuth the picture is green so I sent emails to relevant websites questioning this and got following replies..

from seeds of change .. "We have a great picture of it in our catalog on page 50 and it is most definitely red. It is also called Red Aztec Spinach. Chenopodium berlandieri is the species we sell. Maybe there is another one that is not red?" ..

from Gourmet Sleuth I got " I can’t speak for what product Seedsofchange.com is referring to but huazontles are long stemmed greens with tiny flower buds (which we can confuse you further because technically the buds are fruit..) The plant grows long stalks, has serrated leaves and the stalks get tipped with seed bundles. The seed bundles are prepared and eaten like a vegetable. The only huazontles I’ve ever seen are green in color so if they are selling something red.. not sure what that would be. That being said this plant does grow in the U.S. (treated like a weed) but was eaten by Native Americans. Our reference is Diana Kennedy, well known writer and considered one of the best authorities on Mexican food and culinary culture. We have more description in our dictionary (this link is to our new site which is still under development but feel free to check out the info)http://dev1.gourmetsleuth.com/Dictionary/H/Huauzontle-6125.aspx

THEN researched Chenopodium berlandieri and found pictures at Google Image Search which show most green but a couple red however no explanation as to why red or green or if 2 different varieties ... similarly on Wikipedia .. different varieties but no red .... can you please help me ... thanx 124.179.215.251 (talk) 05:21, 14 July 2009 (UTC)[reply]

Red leaves in plants are usually caused by the [anthocyanin] content. Some varieties will naturally contain more (cf red cabbage, near-black bell peppers). —Preceding unsigned comment added by KoolerStill (talk • contribs) 10:14, 14 July 2009 (UTC)[reply]

I have no idea if this is relevant, but in my garden I have both Red Orache and Fat Hen, both members of the Chenopodium family. If you look at our article on Atriplex you will see that there are plenty of members of this family which are edible. I don't know if this is what you were looking for but it might help.--TammyMoet (talk) 18:50, 14 July 2009 (UTC)[reply]

Mercury

How do humans eliminate mercury and it's compounds? It says that fish store mercury faster than they eliminate from their bodies. How does this compare with humans? Are that "natural" chelating agents that can be found in the (human) diet?174.3.103.39 (talk) 08:40, 14 July 2009 (UTC)[reply]

As far as I'm aware, humans also store mercury in adipose tissue, and eliminate it very, very slowly (over a period of years). Even worse, there are currently no known natural chelating agents, either in the human diet or anywhere else (not even the "miraculous" Acai berry). There are some synthetic chelators available (such as British Anti-Lewisite) to help the body get rid of mercury; however, they should only be used in case of severe mercury poisoning and then only with a doctor's prescription, because they are themselves somewhat toxic (like many other strong medicines). FWIW 76.21.37.87 (talk) 09:04, 14 July 2009 (UTC)[reply]

Judging from the mercury poisoning article, there's no particular elimination of mercury by the human body :-( quoting [3]: Methylmercury is believed to cause toxicity by binding the sulfhydryl groups at the active centers of critical enzymes and structural proteins. This is just my guess but i'm thinking from this, that mercury is expelled when enzymes and protein in the body are destroyed, as they frequently are. The rate of metabolism would seem to be the crucial factor then, but this is just my layman thoughts on it. Brain cells are not renewed the same way that say skin cells are, so mercury in the brain probably stays there :-(( EverGreg (talk) 09:15, 14 July 2009 (UTC)[reply]

Lack of hunger

I seem to remember reading something about a lack of hunger, even though a person hasn't eaten for several hours, as a sign of something wrong with them. Does this ring any bells with anyone? Dismas|^(talk) 09:08, 14 July 2009 (UTC)[reply]

I'm afraid that lack of hunger is a symptom of a very wide rang of diseases, though I can't recall one that has it as its only symptom. EverGreg (talk) 09:17, 14 July 2009 (UTC)[reply]

And, of course, if there was, we wouldn't be allowed to talk about it. --Anon, 11:10 UTC, July 14, 2009.

That is completely incorrect. We can discuss medical information all we like. We cannot attempt to diagnose a person through the Reference Desk if the person claims to have a lack of hunger. -- kainaw ™ 11:21, 14 July 2009 (UTC)[reply]

The symptom of lack of hunger is called Anorexia (symptom), not to be confused with anorexia nervosa, which is the well-known eating disorder. From the anorexia (symptom) article:

Anorexia (deriving from the Greek "α(ν)-" (a(n)-, a prefix that denotes absence) + "όρεξη (orexe) = appetite) is the decreased sensation of appetite. While the term in non-scientific publications is often used interchangeably with anorexia nervosa, many possible causes exist for a decreased appetite, some of which may be harmless, while others indicate a serious clinical condition, or pose a significant risk.

So it might be something; it might be nothing, but please consult a qualified doctor if you're worried.AlmostReadytoFly (talk) 12:13, 14 July 2009 (UTC)[reply]

Hmm, thanks for the link to the symptom of anorexia. And to those who didn't get their "we don't give medical advice" jackboots on, thank you! Dismas|^(talk) 16:43, 14 July 2009 (UTC)[reply]

Jenkem

[post removed by user]

You asked this question yesterday, then removed it today, along with an answer. 87.114.25.180 (talk) 13:00, 14 July 2009 (UTC)[reply]

[post removed by user]

I didn't decline to participate in helping you, I declined to participate in an experimental test of the hypothesis. I agree that you're asking a different question now. Before you asked whether the idea could be ruled out in principle, and I said I thought not. Now you're asking whether there is evidence, and the answer is that I don't know. It would surprise me if anybody had studied this, but I don't know for sure. Snopes has a lot of information about this, and classifies it as an urban legend. Looie496 (talk) 19:45, 14 July 2009 (UTC)[reply]

I think Snopes classifies it as a legend that "Jenkem" is popular in the USA. They don't seem to have any references on whether or not it's possible. APL (talk) 18:48, 15 July 2009 (UTC)[reply]

Remove your own posts if you want, but don't touch others'. If you don't like the replies given you for free by volunteers, feel free to ask your questions elsewhere. 87.114.25.180 (talk) 21:14, 14 July 2009 (UTC)[reply]

Oh joy the "it's free so don't complain" line. Sure is an easy excuse for not trying. I've removed MY OWN posts and left everyone elses, as you suggested. Onesevensix 77 (talk) 23:06, 14 July 2009 (UTC)[reply]

Someone has tried to help you. You just don't like the answers, for whatever reason (since you haven't bothered to explain why that person who has tried isn't answering your question) Nil Einne (talk) 01:08, 15 July 2009 (UTC)[reply]

If I have to explain why the question isn't being answered there isn't much hope for getting a good answer anyway. Onesevensix 77 (talk) 04:44, 15 July 2009 (UTC)[reply]

That's funny... You think you should be entitled to "complain" about a free service and people not "trying", and you don't even have the decency to explain why you are complaining or you think people are "not trying" after waiting less then a day. I was reasonably polite before, but I don't care anymore. It seems to me Looie496 has answered both your questions quite well. You just don't like the answers, because the answers are that 1) No you can't say it's impossible or rule it out in principle because a lot of weird things can be produced under fermentation 2) It's unlikely anyone has studied whether you can get high off the fermentation products of shit, because no one gives enough of a shit about a silly hoax to waste their time on such a thing and so there's likely no definite evidence either way; and it appears to me you want to be able to say the jenkem thing is impossible but you can't. I'm sorry to have to tell you, but life is like that. There isn't always definitive evidence for something and sometimes you have to accept that, or if you really want definitive evidence, do the experiments yourself. Nil Einne (talk) 13:01, 15 July 2009 (UTC)[reply]

If the replies had bothered to explain that there was no evidence to cite then I might agree with you. As it was Looie496 reply just stated the obvious and implied I had asked him to sniff his shit. Of course I did not expect anyone to actually attempt this themselves to answer my question, I was expecting someone to just provide a few links to articles and web pages (of which do exist, despite your claims that no one gives enough of a shit to research into it). Then when I politely removed my original question and rephrased it to get better replies (note that I was entirely civil and did not even comment on Looie496s reply, I simply wanted to ask my question again in a better way) I was berated with "you've already asked this" responses and resistance to helping me. Onesevensix 77 (talk) 06:14, 16 July 2009 (UTC)[reply]

faster then the speed of light?

I understand that light will travel through a vacuum at something like 3*10^8 m/s, but are the individual photons actually traveling faster since they are not going straight, but are instead traveling as a sine wave? What is the actual speed of the particles then? Googlemeister (talk) 14:42, 14 July 2009 (UTC)[reply]

When an electromagnetic wave is depicted as a sine wave, the sine wave represents the magnitude (and possibly the orientation) of the wave's electric field. It does not represent a displacement in space of the photons or anything else. -- Coneslayer (talk) 14:57, 14 July 2009 (UTC)[reply]

boy is that the wrong answer. The real answer is that WHATEVER LIGHT DOES WHEN YOU SEE IT AS A SINE WAVE (even if it did move up and down, or in and out, or back and forth, or whatever else) is something ENTIRELY DIFFERENT FROM WHAT IT DOES WHEN YOU SEE IT AS A PARTICLE. Read wave/particle duality. You simply can't apply particle physics to the waveform of light, and vice versa. Beyond that, what a sine wave WOULD represent to a particle, is irrelevant. 82.234.207.120 (talk) 14:59, 14 July 2009 (UTC)[reply]

I've corrected a minor spelling error in the link, it should work all right now. 76.21.37.87 (talk) 01:48, 15 July 2009 (UTC)[reply]

That's not really a helpful way to think about wave-particle duality. Light doesn't behave like particles travelling in a wavy trajectory. It behaves a bit like a wave travelling in some sort of medium (which made people think there was a luminiferous ether), or a bit like particles travelling in straight lines. AlmostReadytoFly (talk) 15:08, 14 July 2009 (UTC)[reply]

It looks like we need Stephen Hawking again. Is Stephen Hawking in the house? Bus stop (talk) 15:15, 14 July 2009 (UTC)[reply]

You can imagine light to be an EM wave. The electric and magnetic field vectors are sinusoids perpendicular to each other and the direction of propogation. This wave travels at the speed of light. Or, you can imagine light to be a photon, that is, a particle, moving at the speed of light. Hence, it has properties of both waves and particles. What property it will exhibit depends on the experiment. For example, you can imagine an experiment of Diffraction. Assume the source is such that it emits a single photon. The diffraction pattern is still seen. This means light is released as a particle and diffracts as a wave. However, by the complimentarity principle, it can neber exhibit both particles simultaneously. So, its your choice how you imagine light, but it still travels at the constant speed of light. Rkr1991 (talk) 16:29, 14 July 2009 (UTC)[reply]

Obviously the light itself travels at the speed of light, there is no question on that. But the photons that make up the light are going faster or not? They have to exist, if it behaves as both right? Googlemeister (talk) 16:48, 14 July 2009 (UTC)[reply]

To make it easier to understand... You are imagining that there are little particles called photons. Your imaginary particles are travelling at whatever speed you like. Realistically, there are no particles. The thing you are calling a particle is a thing that, at times, exhibits behaviour similar to a particle. At other times, it does not. You can consider the fact that it should travel faster than light if it was actually a particle an instance of when it is not behaving like a particle if you like. -- kainaw ™ 16:54, 14 July 2009 (UTC)[reply]

From my understanding of light, it behaves either as a particle, or as a wave, only based on if it is being observed or not. Thus when it is not being observed, it is both. Thus particles would have to be able to travel faster then the speed of light. Is the logic incorrect, or is my understanding of the quantum nature of light off? Googlemeister (talk) 18:09, 14 July 2009 (UTC)[reply]

Photons travel in straight lines, not in sine curves. They travel in straight lines at exactly the velocity of light. Nothing about light travels in a sine curve. When people depict the electric and magnetic fields as being shaped like sine waves, it is a metaphor for a certain mathematical abstraction, which you are taking too literally. People also talk about alternating electric currents as being sinusoidal, but that does not mean the electricity travels through the wires along a sinusoidal path, or that there is anything else taking a wiggly path through space. —Dominus (talk) 18:25, 14 July 2009 (UTC)[reply]

BTW what you said about it behaving as a wave or particle based on wether or not it was being observed: I thought it always did so regardless. Theres something that doesn't happen when you observe it but it is still wave/particle. Isn't the photoelectric affect proof of light as a particle, and that affect is valid when you look or don't, as is the double slit correct?66.133.202.209 (talk) 04:39, 15 July 2009 (UTC)[reply]

Wow... This discussion has gotten way off. Light is not a particle or a wave. It is merely light. Depending on how we set up our experiment, we can show particle-like properties or wave-like properties. However, that is not because light "changes" between the two (as though it knows what experiment we are doing???) nor does it mean that light is "both" a particle and a wave; as though it were simultaneously two things at once. It is just one thing; light, and its behaving the same way all the time. Our models which require us to assign it into a binary system of either "particle" or "wave" is what is the problem... --Jayron32.talk.say no to drama 06:10, 15 July 2009 (UTC)[reply]

Periodicity of ionization energies?

I've been set an exercise which consists of putting in order a series of chemical elements according to their first ionization energy, knowing only their atomic numbers. My textbook says that the first ionization energy increases within each period of the table, but Al has a lower IE than Mg, and S has a lower IE than P, for example. How am I supposed to do the exercise then? Can someone give me a nudge in the right direction? Thank you! --83.34.232.200 (talk) 15:02, 14 July 2009 (UTC)[reply]

There are rules-of-thumb as you see, but sometimes there's no way to be sure without looking up the actual values. Our ionization energy article is quite detailed and surprisingly complex--tells you that the actual specifics of IE are well beyond the general picture. There's a nice graph at ionization too, and you can see both the periodic nature and also the exceptions that don't follow the general trends. DMacks (talk) 15:40, 14 July 2009 (UTC)[reply]

Yes - read the article and look at the graph(s), as a possible hint - try comparing ionsiation energies diagonally if you want to avoid exceptions, also for all but the most dedicated (~~anally pedantic~~) of scientists the difference between Al/Mg is really just a blip (though it is real - not a measurement error)

Look at the bigger picture.83.100.250.79 (talk) 16:06, 14 July 2009 (UTC)[reply]

Artists' impressions of planet surfaces

Can anyone please indicate a good web-site with lots of (scientifically based) artists' impressions of views from the surfaces of planets in our Solar System - thanks. --AlexSuricata (talk) 18:51, 14 July 2009 (UTC)[reply]

[4] Cuddlyable3 (talk) 22:34, 14 July 2009 (UTC)[reply]

[5] will take some digging around in. 71.236.26.74 (talk) 19:31, 15 July 2009 (UTC)[reply]

If you're interested in some very fanciful paintings from before we had close-ups of the actual cratered, uninhabited planet surfaces, Time-Life published a book in the 1960s or even 1970s that imagined planetscapes for all of them — there were forests on Venus with flying alien gasbag creatures. Beautiful. I am pretty sure it's Planets in the Life Science Library, written by Carl Sagan (looks like his first book). Tempshill (talk) 23:18, 17 July 2009 (UTC)[reply]

Big Bang, how did it happen?

I really have no reason to disbelieve the big bang theory, and cosmic background radiation seems to outright prove it in my eyes. But I don't know how it could have actually happened.

The beginning of the universe, as Steven Hawking seems to explain, was a singluarity, similar in type but not scale to black holes. If there was infinite gravitational pull because it was a huge amount of mass in an infitesimal area, how could it possibly blow up?

I don't see it as likely that black holes, no matter how large they are, would explode, and they have some forces tugging outwards on their centers (the gravity of other black holes for example). The singularity at the beginning of the universe would have have gravity, obviously, holding it together, and that would simply overpower every other force that could exist.

I know an explosion happened, but black holes don't explode, and explosions need something to cause them right? Bah, just reading a discover article about steven hawking and this came back into my mind. Please help me understand. Thanks! —Preceding unsigned comment added by 192.234.122.9 (talk) 19:54, 14 July 2009 (UTC)[reply]

All of physics breaks down as you go back towards the original singularity. Therefore, notions of gravity that we understand now did not apply when the big bang occurred. -- kainaw ™ 19:58, 14 July 2009 (UTC)[reply]

Is gravity a theory or a law? Googlemeister (talk) 20:09, 14 July 2009 (UTC)[reply]

Well, Newton's law of universal gravitation is a "law" - but it's modified by things like General relativity - which is a "theory". All that we know about gravity is a mixture of laws and theories. But I hope you are aware that scientists don't use the words "Law" and "Theory" in the sense of "that which must be obeyed" and "theoretical". In science, those words mean something quite different. SteveBaker (talk) 20:17, 14 July 2009 (UTC)[reply]

Newton's "laws" of gravity are wrong and have been superseded by Einstein's "theories" of relativity. A Quest For Knowledge (talk) 02:58, 18 July 2009 (UTC)[reply]

I wouldn't go so far as to say that Newton's laws are completely wrong. They were based on empirical data, and are now considered to be an excellent approximation for most practical applications where a model of gravity is necessary. They break down in the extreme cases where the theory of relativity must be utilized. AniRaptor2001 (talk) 07:00, 21 July 2009 (UTC)[reply]

The fact is that we don't know why. We know for sure that it happened - but there is a real problem here. Just as with black holes, when distance goes to zero - many other numbers become infinite. Density is infinite, gravity is infinite, but any distance-related repulsive forces (such as the forces that keep the atoms nicely spread apart - or perhaps any repulsive forces due to dark matter and dark energy) also become infinite. Weirder still - all of space was ALSO compressed into that infinitesimal dot. Worse still, the fundamental particles we know about today probably didn't exist back then. Fundamental laws like the Pauli exclusion principle and the Heisenberg uncertainty principle are violated. So the physics of that first gazillionth of a second are really tough to figure out. We have a pretty good idea of the way things were a few milliseconds after the big bang started...but we don't (yet) have a good handle on the absolute zeroth instant. The physics of the interior of a black hole where some of those weirdnesses ought to be playing out - might (in theory) give us a useful starting point to study that - but the event horizon of black holes forever prevents us from studying them in any useful manner. SteveBaker (talk) 20:17, 14 July 2009 (UTC)[reply]

We don't know that it happened, if "it" means "the beginning of time". When you extrapolate the original big bang model backwards you get a singularity about 14 billion years ago, but people stopped taking that seriously when inflationary cosmology caught on, because inflationary models don't have an analogous singularity at a well-defined time in the past. Physicists still talk about the "beginning of the universe" being 14 billion years ago, but they don't really mean it (see Age of the universe#Explanation). In chaotic inflationary models the expansion that we see started as literally a kind of explosion in a pre-existing universe triggered by a certain kind of quantum fluctuation. The background universe in which that happened could have existed forever for all we know. Hawking has a pet idea about the origin of the universe called the no-boundary proposal which he talked about in A Brief History of Time, possibly misleading readers into thinking that it's part of the standard cosmological model. It's not, it's actually pretty fringe. Other physicists take Hawking seriously but they don't necessarily agree with his ideas about cosmology and quantum gravity (and they certainly don't see him as a genius the way the general public seems to). -- BenRG (talk) 22:09, 14 July 2009 (UTC)[reply]

And it's worth pointing out that Brief History of Time is, by the standards of cutting-edge theory, getting a bit long in the tooth. --98.217.14.211 (talk) 22:47, 14 July 2009 (UTC)[reply]

The general public (I include myself here) considers anybody who can understand this mindbending stuff in anything more than a superficial way to be a genius, for some definition of "genius". --Sean 22:54, 14 July 2009 (UTC)[reply]

Alumina ceramic

What is it. in laypersons terms? What does it look like? I read in a book that it is elastic - seems very odd for a ceramic. Is it partly metal, partly silicon, since ceramics are made from clay, and clay I think is mostly silicon? Is it a recent invention? 78.147.131.187 (talk) 20:19, 14 July 2009 (UTC)[reply]

They make sharpening stones (whetstone) out of it, amongst other things - it's usually light grey (or white when pure) in colour, and just like unglazed ceramic - except maybe a bit harder than the average. There's no silicon in it.83.100.250.79 (talk) 20:57, 14 July 2009 (UTC)[reply]

This image is almost certainly an alumina whetstone - if not it looks identical to one

See Ceramic for a wider definition of a ceramic which is not confined to "made from clay through heat"83.100.250.79 (talk) 22:19, 14 July 2009 (UTC)[reply]

It's not elastic in any real, common world sense. At all. 83.100.250.79 (talk) 22:22, 14 July 2009 (UTC)[reply]

See Elastic for the different definitions of the term - they are different.83.100.250.79 (talk) 22:37, 14 July 2009 (UTC)[reply]

Backup Heart

After reading a news story about how a girl survived with two hearts I started to wonder if humans could conceivably live with a backup heart their whole lives. Would it be possible to have a circulatory system with two pumps where if one fails the system remains viable? TheFutureAwaits (talk) 20:22, 14 July 2009 (UTC)[reply]

In principle, sure. The biological concept is accomplished by the lungs, kidneys, and eyes, among other organs. — Lomn 20:26, 14 July 2009 (UTC)[reply]

It seems a bit iffy to me. If the two hearts didn't beat in PERFECT synchronism - and with approximately the same pressures - then high pressure blood from one heart would flow against the tricuspid valve of the other - and those things are only held shut by the pressure - so they'd blow back open...right? I could imagine all manner of Very Bad Things happening. But we probably need a biologist to tell us more about that. Obviously, other heart designs would be possible that could overcome this...but the Mark I human heart doesn't sound like the right machine for the job. SteveBaker (talk) 20:51, 14 July 2009 (UTC)[reply]

Thanks Steve, this is exactly what I'm getting at. Say you could redesign the human circulatory system. Would it be possible to design a system which could function despite one or many pumps failing? What would such a system look like? TheFutureAwaits (talk) 21:09, 14 July 2009 (UTC)[reply]

Not sure if this is an appropriate analogy, but many invertebrates, such as octopuses, have multiple hearts. -RunningOnBrains^{(talk page)} 21:20, 14 July 2009 (UTC)[reply]

We're trying to answer a question with woefully incomplete information. Were there were actually two functioning hearts linked to the same circulation? Was it actually a birth defect in which instead of a four-chamber heart there were two two-chamber hearts serving the two sides of the circulation (pulmonary circulation and systemic circulation)? The "news" is notorious for hyping up some oddity yet not providing real information about what was going on. Can the OP at least link to the news story? --- Medical geneticist (talk) 21:21, 14 July 2009 (UTC)[reply]

Here's the story if you're really interested [6]. Please note I'm not really interested in learning more about this case, it was just the inspiration for the question. What I'm really interested in knowing is as follows: TheFutureAwaits (talk) 21:30, 14 July 2009 (UTC)[reply]

Say you could redesign the human circulatory system. Would it be possible to design a system which could function despite one or many pumps failing? What would such a system look like? TheFutureAwaits (talk) 21:30, 14 July 2009 (UTC)[reply]

It would look like a guy with two or more hearts, each capable of pumping hard enough to support life. They would be connected in parallel and share the same nervous impulse. In the event of failure there would have to be some sort of sphincter or valve preventing back flow round the failed organ. —Preceding unsigned comment added by 83.100.250.79 (talk) 22:43, 14 July 2009 (UTC)[reply]

I don't see how they could be in parallel. If the second heart fails then the first one can only pump into the opening of the second, after which everything gets clogged. I suppose there could be some side artery between the first and second heart where blood could go around the second and back into the main artery. Not sure if this could actually work though. TheFutureAwaits (talk) 23:46, 14 July 2009 (UTC)[reply]

You may have misunderstood. See Parallel circuits. APL (talk) 00:36, 15 July 2009 (UTC)[reply]

Serial hearts could also (in theory) work. By the way, real hearts actually do have such valves. Axl ¤ [Talk] 16:09, 15 July 2009 (UTC)[reply]

What are the odds?

I just ate a bag of peanut M&M's...yes, I know...an entire bag is kinda piggy. Anyway - I tore the end off of the bag and dumped out the usual 30 or so randomly colored M&M's into a shallow dish on my desk. I'm working - concentrating on a tough programming problem (rendering shadows cast from a non-uniform point source - if you must know) - and I swear that I am paying zero attention to picking up M&M's...until there are only seven left - when I happen to notice that they are ALL blue. This seems like a rather improbable thing...there are maybe 5 colours - so the odds are something like eighty-thousand to one against this happening by chance. So I'm wondering whether my subconscious doesn't really like blue M&M's and hasn't been telling the conscious "me" all this time? I should probably repeat the experiment a few times...right? SteveBaker (talk) 20:46, 14 July 2009 (UTC)[reply]

There could have been an error at the packaging plant and some bags did not get the proper mix of colors. I also recall a couple of contests from years ago where the winning bag was all 1 color. You could have just eaten a $1,000,000 bag of M&Ms. Googlemeister (talk) 20:51, 14 July 2009 (UTC)[reply]

No - I'd have noticed immediately when I dumped them out if they were all blue. I was obviously concentrating on the bag when I opened it

Maybe blue ones are heavier? but tell us more about you're non uniform point source - that sounds more interesting - though not that difficult on the surface - a point source always produces sharp shadows no matter what the intensity of the light - sounds like you just need more bits in the shadow map to express the non-shadowed intensity - it's always easier to say rather than do isn't it.83.100.250.79 (talk) 20:53, 14 July 2009 (UTC)[reply]

Yes - but it's omnidirectional so I can't do the usual "planar rendering from the point of view of the light source" trick - I've got to mess around with rendering to a cube-map. Anyway - I don't need help with that - I need to know about my brain's hitherto unsuspected aversion to blue food! SteveBaker (talk) 20:56, 14 July 2009 (UTC)[reply]

Coincidences do happen. Also, while the odds may be one in 80,000, how many packets of M&M's have you eaten in your life? Enough, I imagine, for the odds of the last seven M&M's in one of those packets being all the same colour being significantly higher. Also, it isn't 80,000:1, it is more like 16,000:1 - you don't want the odds of the last 7 being blue, you want the odds of them all being the same colour. You would have been just as surprised had they been all red. --Tango (talk) 21:24, 14 July 2009 (UTC)[reply]

Excuse *ME*! 80,000 bags of M&M's?! If I'd consumed M&M's every day since 1954 (when Peanut M&M's were first introduced) that would make 4 bags a DAY! Every single day! Now THAT would be "piggy"! SteveBaker (talk) 05:06, 15 July 2009 (UTC)[reply]

You don't need to have had 80,000 bags. Say you've had 1,000 bags, at odds of 80,000:1 (which are wrong anyway, but I'll go with that number), the chance of one of those bags having the last 7 blue would be

1-{\frac {79999}{80000}}^{1000}=0.012\dots

, that's over 1%. Plenty of 1 in 100 chances happen and you wouldn't think twice about it. --Tango (talk) 16:55, 15 July 2009 (UTC)[reply]

You should play the lottery ;) --Mayfare (talk) 21:58, 14 July 2009 (UTC)[reply]

It's a very, very common elementary school science "experiment" to see whether the color distributions in M&Ms and other candies are identical. They are often not, probably due to poor mixing. There is no a prior reason to suspect that the packet actually has even distribution to begin with, which obvious affects the odds-making quite a bit. --98.217.14.211 (talk) 22:29, 14 July 2009 (UTC)[reply]

(edit conflict) Yes that's right, I work in a M&M's factory (peanut division), and the blue ones always go in first. Somedays, when the boss isn't looking we don't bother to shake them to mixed the different colours, sometimes people just forget - "did you shake that one", "think so"... (lie)83.100.250.79 (talk) 22:47, 14 July 2009 (UTC)[reply]

That might actually be close to the truth. Presumably, the open bags are moved beneath a series of hoppers that each spew forth a set amount of M+Ms of a particular colour... --Kurt Shaped Box (talk) 00:29, 15 July 2009 (UTC)[reply]

But they'd have gotten shaken up when loaded into the vending machine, shaken more when dropped three feet into the output hopper - and completely mixed up when I dumped them into the bowl. It's hard to imagine that there would be much correlation between the order they were dumped into the bag and the order they were in the bowl. SteveBaker (talk) 05:10, 15 July 2009 (UTC)[reply]

Color distribution on M&Ms is not even. In the mid-70s Cecil Adams claimed that they were 90% brown and yellow. If the color distribution is still close to that (And I can't say I've noticed.) then your coincidence is even more surprising. APL (talk) 22:46, 14 July 2009 (UTC)[reply]

Of course it's dangerous to interpret any given event, but there's quite a bit of experimental work in the psychophysics literature showing that people are generally averse to blue-colored food. In fact there is even evidence that coloring a food blue influences the way people perceive its flavor, for example this paper. Looie496 (talk) 22:48, 14 July 2009 (UTC)[reply]

As someone who likes blueberries, I respectfully disagree. 76.21.37.87 (talk) 07:01, 17 July 2009 (UTC)[reply]

That's what I was wondering. SteveBaker (talk) 05:10, 15 July 2009 (UTC)[reply]

Before concluding that anything miraculous has occurred I want to know more about how one pays zero attention to picking up M&M's but picks them up anyway. Some brain activity must be involved in reaching out to a particular M&M. Were the M&M's in the field of view? What colour was the dish? Were more than one M&M touched at a time? Can the subject taste the difference between any M&M colours while blindfolded (a follow-on experiment) ? Which colour(s) of M&M eaten to excess would cause the subject to feel the most shame about being piggy? A point source cannot be non-uniform. It sounds like you have a ray tracing exercise. Cuddlyable3 (talk) 23:00, 14 July 2009 (UTC)[reply]

Well - my conscious mind was not carefully picking the non-blue ones first. One can grab a random candy from a dish without actually consciously thinking about it. I wasn't CONSCIOUSLY choosing to eat the non-blue ones...which is what makes me wonder whether this decision had been made by some lower level brain function. The M&M's were in a chromed plastic dish - it would have been visible in my field of view - but I wasn't conscious of looking at the dish - my gaze was mostly fixed on my computer screen. I don't know what you mean by "were more than one M&M touched at a time". I'm pretty sure I can't tell the difference in the flavor. Piggyness comes about from not PLANNING to eat more than a couple of M&M's but then belatedly noticing that there were only seven left. It's computer graphics - not physics - the point source does whatever the heck I tell it to do. If I say it's a non-uniform point source...then that's what it is! In this case, imagine a very small lightbulb with a lampshade over it (idealised as a point source because it makes the math easier) such that the light from it is not evenly distributed. This is for computer games - performance is at a premium and ray tracing is WAY out of the realms of the possible! SteveBaker (talk) 05:01, 15 July 2009 (UTC)[reply]

I would imagine a "non-uniform point source" would be a source which emits different light in different directions, but all from one point. --Tango (talk) 00:06, 15 July 2009 (UTC)[reply]

Yes, exactly. SteveBaker (talk) 05:01, 15 July 2009 (UTC)[reply]

Like an airport beacon (rotating white / green)? 76.21.37.87 (talk) 06:15, 17 July 2009 (UTC)[reply]

Explaining Were more than one M&M touched at a time?: this question investigates the process by which each M&M was selected unconsciously. The subject might A) have aimed to pick a particular M&M and operated arm, wrist and fingers appropriately, or B) grabbed a bunch of M&Ms and then used the sense of touch in the fingers to drop all except one M&M to eat, or C) none of the above. Supplementary question: how many M&Ms does the subject typically have in the mouth at the same time? I'll repeat the question Which colour(s) of M&M eaten to excess would cause the subject to feel the most shame about being piggy?.Thank you for explaining your non-uniform point source. Perhaps you use a this or this shading of objects. Look towards the light source and apply the same model. Multiply the modelled illumination with the modelled reflection and then you can play. Cuddlyable3 (talk) 12:59, 15 July 2009 (UTC)[reply]

Yeah - I've been doing computer graphics for 25 years...I know about shading algorithms (which is what Gouraud and Phong are...well, almost, they are actually surface normal interpolation strategies). My problem is to do with casting shadows - not those kinds of "self-shadowing" things. I was certainly eating them one at a time...I wasn't paying attention to how I was picking them up - but I'd have to say it was almost certainly one at a time. The subject's conscious brain doesn't give a damn about the colors - piggyness is an approximately linear function of number of M&M's consumed divided by elapsed time between first and last M&M - the value of the function is explicitly defined to be zero when the number of M&M's consumed is less than 2. The subject's unconscious brain doesn't seem to comment on piggyness - since it's shovelling them in at a high rate. However, the issue of color is the question at hand. SteveBaker (talk) 19:26, 15 July 2009 (UTC)[reply]

If you told us the number of M&Ms in the bag, and the total number of blue ones, then the probability could be calculated. Its an example of the classic beads in an urn (no replacement) combinatorial problem. I'm trying to remember the formula. But, assuming that the probability is the same as the first 7 m&ms being blue, then the probability would I think be B/M x (B-1)/(M-1) x (B-2)/(M-2) ..... x (B-7)/(M-7). Note that the other n million people who have eaten a bag of M&Ms and whose last seven items were not blue, have not reported it to Wikipedia. 92.27.155.47 (talk) 23:18, 14 July 2009 (UTC)[reply]

Assuming he didn't count them in advance you have to assume they are independent with equal chance of each colour (you could assume each bag has equal numbers of each colour, but that doesn't seem to be the case), so it is just 5⁶ (there are 6 M&M's which need to be the same colour as the first one, you don't care what colour the first one it). --Tango (talk) 23:39, 14 July 2009 (UTC)[reply]

Please explain how you caculated " 5⁶ "? I am not familiar with M&Ms, but if you are supposing that there are five different colours and that they are in equal proportions, then your estimate for all-blue would be (1/5)⁷ which is one in 78125, or (1/5)⁶ which is one in 15625 for seven in a row being the same colour. Actually, that is correct only for bags of infinate size or for where the M&Ms are put back in the bag: when a blue M&M is removed, it changes the proportions of the remaining colours in the bag, so the B/M x (B-1)/(M-1) x (B-2)/(M-2) ..... x (B-7)/(M-7) calculation is more correct. 78.145.23.157 (talk) 20:26, 16 July 2009 (UTC)[reply]

You might care about the color of the first one. If his final seven M&Ms had all been brown, the most common color, would he have considered it notable? APL (talk) 00:33, 15 July 2009 (UTC)[reply]

Are brown significantly more common? It's been ages since I've had a packet of peanut M&M's. --Tango (talk) 03:15, 15 July 2009 (UTC)[reply]

You can actually order M&M's in 60 pound bags of single colors of your choice from the M&M web site, including colors that you don't find in the normal retail packs, like black and white. 70.90.174.101 (talk) 04:02, 15 July 2009 (UTC)[reply]

This describes the color distribution: http://joshmadison.com/article/mms-color-distribution-analysis/ 70.90.174.101 (talk) 04:05, 15 July 2009 (UTC)[reply]

Not really - these were PEANUT M&M's. SteveBaker (talk) 05:01, 15 July 2009 (UTC)[reply]

The whole point here is that, while it is unusual, such event occuring truly randomly is not impossible. It isn't that YOU at 80,000 bags of M'n'Ms. It's likely that 80,000 bags are consumed pretty regularly (I'd even hazard DAILY), so such an event happens to someone every day. That it was your turn today is rare, but not impossible. Look, I have a buddy that lost a poker hand (7-card stud, no wilds) where he had a straight flush and lost to a higher straight flush. You can play poker your whole life and probably never even play in a hand where a straight flush occurs; and yet he was in one with two. It is weird, but any event based on random chance DOES happen. --Jayron32.talk.say no to drama 06:03, 15 July 2009 (UTC)[reply]

The current page at mms.com doesn't have percentage information but this archived page does: 12% brown and red, 15% yellow and green, 23% blue and orange. I wonder how much they paid the consulting firm that came up with those percentages. Anyway, the chance of n randomly selected Peanut M&Ms being all the same color (with replacement) is 2·(12ⁿ+15ⁿ+23ⁿ)/100ⁿ. For n=7 that's about one in 14,000. Without replacement it would be somewhat more unlikely, but I'd need to know the total M&M count per pack for that. -- BenRG (talk) 09:45, 15 July 2009 (UTC)[reply]

Hmmm... The color distribution has changed drastically since that Cecil Adams column in the 70s. APL (talk) 12:51, 15 July 2009 (UTC)[reply]

Alien hand syndrome shows that the hemisphere which doesn't have access to the speech center can indeed have its own opinions about things. I guess we can assume your two hemispheres aren't in serious disagreement over whether you like blue M&Ms, but I'm just saying that the psychological explanation is feasible, and perhaps a more likely explanation than the 1 in 80,000 chance. It seems likely to me that it takes some small but significant degree of conscious effort for you to recognise bright blue things as food, and so you're less likely to put those ones in your mouth automatically. 213.122.68.146 (talk) 06:41, 15 July 2009 (UTC)[reply]

If they were in your peripheral vision you may have subconsciously been picking the ones that stood out more/had higher contrast against the bowl/other M&M's given the ambient lighting. Zunaid 11:50, 15 July 2009 (UTC)[reply]

My guess is: you actually prefer the blue ones and therefore subconsciously saved the best ones for last! Sort of like the old Smarties commercial: "Do you eat the red ones last?" I found myself saving the red ones to the end without even realizing that I was doing so! Now, I consciously eat my M&Ms from my least favorite color (they all taste the same!) to my most favorite (blue and red). —Preceding unsigned comment added by 216.154.20.38 (talk) 14:52, 15 July 2009 (UTC)[reply]

I just ate a whole bag of peanut M and M's and didn't pay attention to any of the colors. after reading this post, I will in the future! cheers, 10draftsdeep (talk) 18:13, 15 July 2009 (UTC)[reply]

"M&Ms are Tasty! They melt in your mouth, not in your hand. Melting before being consumed was a problem with chocolate, which was otherwise highly useful as an emergency ration for soldiers. In World War 1, the U.S. Army issued chocolate bars to soldiers to be eaten for energy needs when normal food could not be brought to the at front line positions. Knowing that any normal guy would eat a tasty chocolate bar long before the hypothetical emergency, the Army adulterated the chocolate bars with sawdust and kerosene. Edison (talk) 01:50, 16 July 2009 (UTC)[reply]

EWWWWWWWWW!!! 76.21.37.87 (talk) 05:18, 17 July 2009 (UTC)[reply]

Sounds like they should have just issued a lump of salted lard. Googlemeister (talk) 20:25, 21 July 2009 (UTC)[reply]

I once knew a bloke who carried a package of SweeTarts as an emergency snack because he didn't like SweeTarts. —Tamfang (talk) 19:14, 20 July 2009 (UTC)[reply]

Good idea, I might consider carrying a package of Reese's Pieces as an emergency ration... :-) 76.21.37.87 (talk) 06:00, 21 July 2009 (UTC)[reply]

Solubility of Ionic Compounds

Hello. If ionic compounds are polar and like dissolves like, why are some salts water-insoluble at SATP? Thanks in advance. --Mayfare (talk) 21:51, 14 July 2009 (UTC)[reply]

"like dissolves like" is a general observation of a certain trend, not a fact (and definitely only a result not a physical law or the cause of anything). If "whatever holds molecules together and to each other" is stronger than "whatever interactions happen between solute and solvent", the chemical is not very soluble. See solubility for a detailed discussion. DMacks (talk) 22:11, 14 July 2009 (UTC)[reply]

In the case of ionic salts, that would be the relative strength of the ions' electrostatic attraction to each other vs. water molecules. If the ions are more attracted to each other than to water, then the salt will not dissolve. Generally, salts where one or both ions are monovalent (with the exception of some fluorides) are water-soluble, whereas those where both ions have a valence of 2 or more are water-insoluble because their electrostatic attraction is much stronger. Note also that for the purpose of determining solubility, fluoride ions behave as though they have a valence of 2 or more, even though they really are monovalent.

76.21.37.87 (talk) 01:04, 15 July 2009 (UTC)[reply]

In my quest for knowledge: this is because of fluorine's very high electronegativity, right? -- Aeluwas (talk) 16:15, 15 July 2009 (UTC)[reply]

When they say "fluoride ions behave like they have a valance of 2" I think what is meant that fluoride ions (F-) show similar solubility characteristics as 2- ions eg sulphate - this is because of F- ions small size ... small size or high charge makes the ion more strongly interact with electrophiles. It's not the electronegativity.

Also if a compund is only partially ionic the solubility is affected (eg CuI is insoluble, but KI is soluble) - there are a lot of factors, but it's simpler when both the anion and cation are good at forming ions eg Cl- , K+ , Mg2+ , NO3- etc...83.100.250.79 (talk) 22:25, 15 July 2009 (UTC)[reply]

Yeah, that's what I meant to say. Thanks! 76.21.37.87 (talk) 01:02, 16 July 2009 (UTC)[reply]

The Limit of heat?

I understand that there is a limit to the degree of cold (absolute zero), but is there a limit to how hot things can get? Obviuosly in the moments after the big bang, the temprature would of been huge, but can there be a higher temprature, either naturally (in supernovas etc) or synthetically (in collisions and heating [I read that scientists have heated a substance to 510 million degrees!]). Andy (talk) 23:57, 14 July 2009 (UTC)[reply]

There is no theoretical limit to the best of my knowledge. There is a practical limit imposed by the total amount of energy in the observable universe, of course. You may be interested in the concept of negative temperature, which is, in a sense, temperature hotter than infinitely hot. --Tango (talk) 00:04, 15 July 2009 (UTC)[reply]

Absolute hot 87.114.25.180 (talk) 00:34, 15 July 2009 (UTC)[reply]

Good stuff, very interesting, just out of curiousity, what is the hottest temprature ever created, both in a lab or naturally? Cheers. Andy (talk) 00:41, 15 July 2009 (UTC)[reply]

That would be the temperature of a thermonuclear explosion, which is in the billions of degrees (Celsius). 76.21.37.87 (talk) 00:53, 15 July 2009 (UTC)[reply]

On second thought, some blue giant stars or supernovas may be even hotter. FWiW 76.21.37.87 (talk) 00:55, 15 July 2009 (UTC)[reply]

Stars are thermonuclear explosions. --Tango (talk) 03:10, 15 July 2009 (UTC)[reply]

The temperature was ludicrously high just after the Big Bang. --Sean 14:10, 15 July 2009 (UTC)[reply]

That's not quite analogous to absolute zero. Absolute hot isn't the highest temperature achievable, it's the highest temperature that our theories are capable of describing meaningfully. --Tango (talk) 03:13, 15 July 2009 (UTC)[reply]

Planck temperature is theoretical limit. --manya (talk) 04:35, 15 July 2009 (UTC)[reply]

As Tango states, defining a limit is difficult, because what is "hot" can be counter-intuitive. Your scale goes in a loop from kind of +0K (cold) to -0K (hot). Hotter than 10^32 K is of little physical relevance (or at least doesn't make sense until we figure out quantum gravity), though, as Ranemanoj said. —Anonymous Dissident^Talk 16:33, 15 July 2009 (UTC)[reply]

Indeed, as AD states, we need to figure out quantum gravity before knowing what happens around Planck temperature. It might well be that there is a limit, but it won't be necessarily the current definition of Planck temp. (also because the choice of using G instead of 8πG in that def. is quite arbitrary, and one which I'd disagree with). There might well be no limit at all. We just don't know it yet. --A. di M. (talk) 16:55, 15 July 2009 (UTC)[reply]

Show me a system in a container which you claim is at the highest possible temperature, and I claim I could heat it up a bit. There is no "highest possible temperature" unlike absolute zero. Edison (talk) 01:45, 16 July 2009 (UTC)[reply]

This does not prove that there is no highest possible temperature --- it just proves that it cannot be reached. See Achilles and the Tortoise (same holds with speed of light and acceleration). (Might be there is none but your argument isn't a proof for it.)95.112.156.108 (talk) 20:31, 16 July 2009 (UTC)[reply]