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January 4

Auxetics utilization in model?

Hey, you guys have helped me out a lot, hopefully the smart people at the refdesk can help me out on something else this time... I am making a model of a stretcher, weaving elastic cord in a 12" by 5" grid in squares about 1/4 inches in size. I wanted to incorporate this into it but seeing as my string is too small in diameter for using thread to work I am unable to practically do so. Is there any practical way to apply this to the entire model? Thanks, ♠The Ace of Spades^♣♥_♦ 00:43, 4 January 2010 (UTC)

jap heating

why dont japs insulate their homes and have central heatring —Preceding unsigned comment added by Thekiller35789 (talk • contribs) 01:04, 4 January 2010 (UTC)

As in Jewish people or Japanese people? And is your don't meant to be distributed, so that japs neither insulate their home nor have central heating, or undistributed, in that japs fail to insulate their homes yet have central heating? DRosenbach ^{(Talk | Contribs)} 02:10, 4 January 2010 (UTC)

i mean japan and both they dont insulate their homes or have central heatring —Preceding unsigned comment added by Thekiller35789 (talk • contribs)

Do you have evidence, like written down somewhere, that says that Japanese people do not heat their homes or insulate them? Where does this information come to you from? --Jayron32 03:33, 4 January 2010 (UTC)

Having visited Dai Nippon during winter I noticed no lack of heating. If there is it may be that the Japanese are a rather stoical race and put up with such things, they are trying to save energy, or it might just be a cultural hold over from days when their 'traditional style' houses were almost entirely wood and rather combustible. Therefore having a large fire was not practical. Fire was taken very seriously (I gather) in old Japan. Not 100% sure but I think arson was a capital offence Also the more common occurence of earthquakes there caused serious problems if a house collapsed on a open fire. --220.101.28.25 (talk) 03:55, 4 January 2010 (UTC)

See here Japanese_houses#Heating for a discussion of heating arrangements --220.101.28.25 (talk) 04:03, 4 January 2010 (UTC)

none of that explains why they dont insulate their homes —Preceding unsigned comment added by Thekiller35789 (talk • contribs) 05:41, 4 January 2010 (UTC)

And you didn't answer Jayron's request for a source that states they don't. Vimescarrot (talk) 09:11, 4 January 2010 (UTC)

I agree some evidence is needed. In any case the lack of central heating and poorly insulated homes is hardly unique to Japan if both really occur there. NZ homes are well accepted to be generally poorly insulated [1] [2] [3] and usually lack central heating. It's sometimes said people from very places with extreme winters have trouble adapting because of how cold our houses are in winter, e.g. [4]. There are some attempts to change both nowadays. [5] A variety of regulatory, traditional and cultural factors contribute and I expect it's difficult to say why except that that's the way things are done. The severity of the winter is likely one. It's clearly going to be far more difficult to have poorly insulated homes in Siberia or perhaps of greater relevance Canada, most of the northern US and most of the UK; then it is in most of NZ. Nil Einne (talk) 10:27, 4 January 2010 (UTC)

Two reasons: 1) Earthquakes. A system of complicated gas pipes in every home and the infrastructure to set one up, apart from the difficulty, would be a massive problem in the event of one of their plethora of quakes. An air con unit on the wall, well screwed-on, is not going to cause explosions or death. Agreed, insulation is non-existant in most places, especially on those single-pane double doors that so many of their apartments have. 2) Energy. Japan imports pretty much all of its energy. Gas would involve some sort of US-Japan pipeline. Oil is more feasible, and electricity to power heating and cooling aircon units is just far more practical. Bear in mind also that Japanese people tend to destroy and re-build houses once every 20-30 years, so the costs of putting all those systems of heating and insulation would also be considerable.

I assume you haven't quoted some kind of proof, as bizarrely requested above, because you have simply lived or visited there and noticed this about their homes. It's true by the way.

Lucas 83 13:59, 4 January 2010 (UTC) —Preceding unsigned comment added by Lukerees83 (talk • contribs)

Some possible reasons are given in this blog post. Nanonic (talk) 14:34, 4 January 2010 (UTC)

again that dosent explain why they dont have insulation —Preceding unsigned comment added by 67.246.254.35 (talk) 01:51, 5 January 2010 (UTC)

I think my post and the blog post given by Nanonic do to some extent. If this is true, it's the way things are done there likely for a variety of regulatory, traditional and cultural reasons and there's unlikely to be one simple reason you can give for why things are down that way. The simplest answer is probably to say they're done that way because that's the way things are done there. Also I forgot to add before, but presuming the situation is as Lucas described or something similar, the helpful thing to do would be to at least explain why you believe it is the case Nil Einne (talk) 11:12, 6 January 2010 (UTC)

Verification Needed - unlikely cite check.

I have doubts that anyone here would be able to verify this source, but I thought that I'd try anyway. If this post is not appropriate for this location, please notify me and I will remove it.

The citation information is:

• Staff (Aug 1, 1990). "FICS Awards Gold Medal To Dr. Press". Dynamic Chiropractic 8 (16): 1.

The relevant information that needs verification is that Dr. Press is the founder and first president of the FICS.

Thanks, DigitalC (talk) 01:07, 4 January 2010 (UTC)

I can't access that document myself but the FICS website states that he was the first president on it's website and past versions of the site state that it was founded at a meeting he convened. A precis of an article in Dynamic Chiropractic (with the full article lurking behind a forever cursed paywall) states he is "founder and past-president of the Federation Internationale de Chiropratique Sportive (FICS)". I don't know if that's what you're looking for? Nanonic (talk) 01:27, 4 January 2010 (UTC)

Hrmm and evermore strange, I've just found that Dynamic Chiropractic have some articles archived on their website and yet neither your article or the one above that is paywalled feature. Nanonic (talk) 01:37, 4 January 2010 (UTC)

Actually, that paywalled one is available here (if you scroll down). Unfortunately, this is not enough for some editors, so having a second source would be beneficial. I think a hard copy would be the only way to verify the info. DigitalC (talk) 02:01, 4 January 2010 (UTC)

Sounds like something that may be difficult to find but you should ask at Wikipedia:WikiProject Resource Exchange/Resource Request first. And perhaps read Wikipedia:WikiProject Resource Exchange too Nil Einne (talk) 10:13, 4 January 2010 (UTC)

cramped legs

Why do my legs get cramped when in a car, but not anytime else, even when im sitting?Accdude92 (talk to me!) (sign) 02:11, 4 January 2010 (UTC)

Perhaps you meant why do my legs get cramps and a possible response would be because they are cramped when you sit in a stuffed car -- when you sit on a couch, though, there is generally a lot of room for your legs to move, and even if they don't move, the mere fact that you have room to move them around may contribute to a lack of the sort of claustrophobic-like feeling that may accompany cramped situations. DRosenbach ^{(Talk | Contribs)} 02:37, 4 January 2010 (UTC)

You also tend to be stuck in one position for a lot longer in a car than when sitting elsewhere, especially if you are the driver - you can't really fidget, and your one leg is nearly constantly flexing to some degree or another. ~ Amory (u • t • c) 04:51, 4 January 2010 (UTC)

Unless you set your cruise control and do not need to change speed often because of traffic and such. That will depend on local conditions. Googlemeister (talk) 15:29, 4 January 2010 (UTC)

Animal intelligence

Could it be that animals know things (and I don't mean in terms of instinct) about the world, such as gravity, peer pressure, earth's orbit, the birth-life-death cycle, etc. but we just don't speak the same language? This is, of course, assuming said organism has a long enough lifespan to appreciate life in a way similar to the way we do, with past experience impressing upon future action. DRosenbach ^{(Talk | Contribs)} 02:35, 4 January 2010 (UTC)

The relevant articles are Animal cognition and Emotion in animals. They are quite detailed. Regarding your specific question about gravity - it is not well posed. A plant seed lacks a nervous system altogether, but it "knows" the local direction of the gravity field. However, no animals and only some humans are aware of Newton's law of gravity, let alone what a graviton is. --Dr Dima (talk) 02:57, 4 January 2010 (UTC)

The same applies to the notion of the Earth orbit. Both plants and animals have circadian and annual rhythms, as a direct result of Earth orbital motion; however, no animals and only some humans are aware of Kepler's laws, or even of the fact that the Sun, Moon, and the stars are not actually attached to the celestial spheres. --Dr Dima (talk) 03:20, 4 January 2010 (UTC)

Considering how hard it was for humans to figure out that stuff, even with our massive cognitive abilities, I don't see why we should assume animals know that kind of stuff. Animals know what they need to know to survive. Some of that is instinct, some of that is learned. To know about gravity in an abstract sense isn't necessary to survive unless you have a very peculiar society that rewards such abstract knowledge (which humans have only really had for a few hundred years out of our long existence as a species). Note that when we have taught animals how to better communicate, they say things like, "Banana me eat banana" and so forth. That isn't definitive, of course, but it doesn't really point towards the idea that animals have all sorts of advanced abstract intelligence just bubbling beneath the surface, which is fairly implausible anyway for the other reasons mentioned. This is not to say that animals are dumb—but their intelligences are quite different than humans'. --Mr.98 (talk) 04:00, 4 January 2010 (UTC)

This may be of interest Tool use by animals or Animal_cognition#Tool_and_weapon_use --220.101.28.25 (talk) 05:03, 4 January 2010 (UTC)Bold text

There's an important conceptual issue here. When we talk about "knowing" something, we must distinguish between implicit knowledge (expressed by performance) and explicit knowledge (expressed by giving the correct answer to a question). There is no doubt that animals have a great deal of implicit knowledge. When it comes to explicit knowledge, though, we face the problem that there is no way to ask an animal a question, so there is no way to probe for explicit knowledge as we would with a human. There have been many attempts to get around this issue, but they all run into difficulties of one sort or another. Looie496 (talk) 18:11, 4 January 2010 (UTC)

I think we would have to say that there is zero evidence that animals think about anything. I have a theory that early human life is not that different than animal life, as concerns consciousness. There was only a point when I became aware of thinking about anything. Prior to that my thoughts were amorphous. They had no form. It is at that borderline that I am making the distinction between "thinking" and "not thinking." My assumption is that animals never get beyond the way consciousness takes its form in the earliest years of human life. But this is utterly unfounded hyperbole spouted by yours truly, in the spirit of original research. Long live Wikipedia. Bus stop (talk) 18:34, 4 January 2010 (UTC)

It depends how you define "thinking". My dog clearly thinks about its dinner. It gazes longingly up at its food bin. It finds elaborate ways (sitting in my lap, for example) to express to me its desire to have dinner at what it considers to be the correct time. When I show her a toy that she wants, and then hide it when she isn't looking, she will first look confused, then search for it, knowing that it has to be somewhere. There is clearly learned cognitive activity going on here at a level that, say, a housefly is utterly incapable of. (When my dog dreams, she is clearly running, woofing, and having experiences as abstract and real to her as my dreams are to me.) I would call all of that "thinking." It is certainly not the same kind of thinking that I do in contemplating my dog. But to say, "humans think, animals don't" requires positing a hard line between human and animal thinking that I just don't see actually existing—similar to concluding that humans "don't know how to smell" when compared to the olfactory senses that a dog has. My dog clearly thinks about food, toys, intruders, keeping the "pack" together, and going on walks... but probably not too much more than that. As to how "conscious" she is... I'm not sure we understand what that means in humans in the slightest, really, so it's hard to say whether it exists in animals, whether it is a thing that you-have-or-you-don't or something else altogether. --Mr.98 (talk) 21:23, 4 January 2010 (UTC)

Healthy skepticism is good, but many people, including scientists, adopt the dogma that only humans can think. It seems that no amount of evidence can convince them otherwise. I think research increasingly demonstrates that while we are by far the most intelligent species on Earth, others know a thing or two about the world as well. When a crow solves a problem on first try and elephants go on a procession for a dead child, I wish they wouldn't dismiss the idea so easily. For your amusement, though I'm sure you'll chalk it off for off-stage coaching, I present this video.[6] Imagine Reason (talk) 02:34, 5 January 2010 (UTC)

Simple magic tricks work with dogs too. If you sit on the ground with your dog's favorite toy - then play 'fetch' (toss the toy so the dog runs off to grab it and bring it back) a couple of times. Now hold the toy above your shoulder and pretend to toss it forwards - but instead just drop it behind your back while flinging your hand forward as if tossing the toy. The dog rushes off after the invisible toy - looks frantically for it. You can then amaze your dog when you "magically" bring the toy out from behind your back. Most dogs can be fooled several times in a row before they figure out the trick. I'm not sure it proves anything about their thought processes though. SteveBaker (talk) 00:48, 6 January 2010 (UTC)

The real debate with animals is not about whether they "think" or not (what the hell does a brain do if it's not "thinking"?!). The debate is whether they are "conscious" or not. That seens to be really impossible to know (although I think it's very likely that higher animals are conscious thinkers). But there are scientists out there who actually doubt whether all humans have "conscious" thought - and some claim that consciousness itself may have evolved fairly recently in human history (in the last 10,000 years perhaps). The trouble is that we really don't have a solid definition for "consciousness" - and without that, we don't even know what we should be testing or measuring to prove or disprove this hypothesis. SteveBaker (talk) 00:48, 6 January 2010 (UTC)

See mirror test for some interesting work done on that very question. Matt Deres (talk) 21:49, 8 January 2010 (UTC)

Expansion in a matter of time

How could 16,000 gallons of water expand to 932 °F steam in a matter of seconds?24.90.204.234 (talk) 02:38, 4 January 2010 (UTC)

Drop it in the sun? Place it under a thermonuclear bomb? The rate of temperature increase is related to the difference in temperature between two areas. Very broadly speaking, if two areas are under a different temperature, the warmer will heat up the cooler (and vice versa) and the rate of change is related to how different the temperature is. So, if you want to heat something up about 1000 degrees very fast, place it in contact with something at say 10,000 degrees... --Jayron32 03:31, 4 January 2010 (UTC)

Actually, it was in a boiler aboard the SS Norway that 16,000 gallons of water expanded to 932 °F steam in a matter of seconds.24.90.204.234 (talk) 03:54, 4 January 2010 (UTC)

Alright then. It expanded to 932° F steam in a malfunctioning boiler. You've answered your own question. At atmospheric conditions, steam is about 1000x less dense (that is, 1 mL of water will generate 1 L of steam). So, 16,000 gallons of water, when converted to steam, at equilibrium with the atmosphere, would "want" to occupy 16,000,000 gallons of space. In a confined space, by Boyle's Law, that means it is at a pressure of 1,000 atmospheres instead. I doubt the boiler could withstand those kinds of pressures. 1,000 atmospheres equals about 15,000 pounds per square inch, give or take. So, imagine the weight of say, a half-loaded Mack Truck balanced on 1 square inch of space. Then put that weight on EVERY square inch of the boiler. No wonder it went KABOOM rather spectacularly... --Jayron32 03:56, 4 January 2010 (UTC)

See this previous discussion from the Science desk archives. Gandalf61 (talk) 10:26, 4 January 2010 (UTC)

There seems to be a major error here. According to the source the water was at 932° F before the event. Because the conversion of water to steam (a gas) requires a great deal of energy, the temperature of the resulting steam would have been much lower than 932° F. In fact, not more than a small fraction of the water would have vaporized before the temperature dropped down below the boiling point. Looie496 (talk) 18:03, 4 January 2010 (UTC)

This question was asked and answered at length a few months ago. Edison (talk) 19:40, 4 January 2010 (UTC)

Cause of death

Flogging seems to imply (but doesn't explicitly state) that loss of blood is the culprit. Is it? Clarityfiend (talk) 03:46, 4 January 2010 (UTC)

Shock is likely a greater influence than just loss of blood. Shock can occur when blood pressure or blood flow is restricted to many vital organs, if ones back is flayed sufficiently it can cause interruptions in blood flow which may result in serious shock, even if "loss of blood" is not as much as say, slashing a major artery. --Jayron32 04:00, 4 January 2010 (UTC)

Note that flogging is normally a form of punishment not intended to kill. A victim is likely eventually to lose consciousness due to blood loss, at which point the punishment loses meaning. Floggings on ships and in prisons were often observed by a doctor who would declare the condition of the victim. A case is recorded Gibson, Ian. The English Vice: Beating, Sex and Shame in Victorian England and After. London: Duckworth, 1978. of a sailor who was put in hospital after going unconscious half way through his alloted strokes; his captain ordered the flogging to continue as soon as the sailor was deemed able to feel it. Cuddlyable3 (talk) 23:45, 4 January 2010 (UTC)

Thanks. Clarityfiend (talk) 07:17, 5 January 2010 (UTC)

"protecting plastics" for cargo

Does anyone apply the protecting group philosophy to whole objects instead of functional groups? I was thinking of like putting a polymer on a certain object, adding some plasticiser... the polymer would be fairly resistant at pH 7 and against heat and moisture, and but when you add an acid/base catalyst (or maybe hydrogen or a reducing agent) the polymer bonds collapse to give you your original product? John Riemann Soong (talk) 04:32, 4 January 2010 (UTC)

Sounds like a messy way to do stuff. The protecting plastic would still exist, albeit in a different form. Disposing of packing peanuts and cardboard seems like an less messy prospect than standing in a puddle of goop that formerly encased your product... --Jayron32 04:38, 4 January 2010 (UTC)

I was thinking of actually protecting something during manufacturing (e.g. a sensitive part) while it underwent various transformations. John Riemann Soong (talk) 05:19, 4 January 2010 (UTC)

Etching, as a process, usually involves "protecting" the un-etched areas of the substrate with some sort of acid-resistant substance, such as a wax, which is later removed. See also Photochemical machining and Industrial etching and Etching (microfabrication) all of which have some methods which operate on the same basic principle; you first protect the areas you want untouched, then you chemically react away the unprotected parts, then you remove the protecting material. Is that the sort of processes you are asking about? There are also multi-pass printing techiniques where plates are treated with special chemicals which allow the ink/dye/toner to stick to certain areas of the plate and not to others, the treated areas are "protected" so they don't attract ink; such plates can then be cleaned and reused. --Jayron32 05:31, 4 January 2010 (UTC)

Yeah, that was sort of what I was thinking about (though not necessarily so nanoscale but that works too) -- I was thinking even two sets of polymers in the style of orthogonal protection. Does the world have any use for a polymer that is fairly tough and resistant ... except with one critical (and useful) weakness. Also, how would I encourage this polymer to fall apart "cleanly" (i.e. it is easily washed off) as opposed to clumps of disgusting stuff you have to chip away? John Riemann Soong (talk) 05:41, 4 January 2010 (UTC)

Electronics are sometimes covered with conformal coating to prevent moisture, dust, and impact damage... it is applied with a physical deposition (spray), not a chemical process, and is not usually ever removed. Nimur (talk) 19:24, 4 January 2010 (UTC)

what do you call this alkene? is it a good dienophile?

Is there a reasonable dehydrogenation reaction that would create a conjugation-stabilised product 2?

Trying to figure what you would call product 2. My IUPAC naming conventions are failing me right now, and never mind what the common name is called. I'm trying to use it for a Diels-Alder reaction. Is there a reasonable reaction (e.g. not reaction conditions like 500C) that would remove H2 from 1?**

Is it a good dienophile? I'm worried the phenyl group is too electron-donating ... how would it affect the transition state? What type of substitution pattern would it encourage if I say, used pyrrole as the dienophile? Also I'm worried about side products like ... the unsaturated C=O bond, polymerisation -- both via DA modes and enolisation....

**I initially thought of synthesising it via phenylacetaldehyde and potassium cyanide, hydrolysing the nitrile and eliminating water ... but some preliminary literature tells me phenylacetaldehyde polymerises very quickly -- Sigma-Aldrich only sells it at 90% purity! :o And oh, cis-trans isomerism is an issue. Any other ideas? John Riemann Soong (talk) 06:14, 4 January 2010 (UTC)

As far as naming, I'd call it 3-phenylacrylic acid. Then I looked it up, and its also called Cinnamic acid, which is readily availible commercially. I see no reason to make #2 when you can buy it probably as cheaply as #1. --Jayron32 06:30, 4 January 2010 (UTC)

Also see Phenylpropanoid for more on this general class of compounds... --Jayron32 06:33, 4 January 2010 (UTC)

It would appear that the entire class of molecules are all produced naturally from Phenylalanine. Also, I see several sources that call #1 in your synthesis "Hydrocinnamic acid" which would indicate that it is more common to work your reaction mechanism backwards; that is to hydrogenate cinnamic acid to make #1 rather that to dehydrogenate #1 to get #2... --Jayron32 06:37, 4 January 2010 (UTC)

Thanks so much! An issue is that I suspect I might need the cis isomer not the trans isomer ... the entire theme of my research is actually various derivatives of amino acids, so a phenylalanine reaction would be perfect.... the most immediate knee-jerk thing that comes to mind is some sort of stereospecific deamination of phenylalanine (or maybe stereoselective deprotonation of the benzylic proton), but I feel that would be really uncontrolled and unreliable. John Riemann Soong (talk) 07:12, 4 January 2010 (UTC)

Well, what are you doing with the Cinnamic acid? What's the next step? Is THAT product stereospecific? --Jayron32 07:14, 4 January 2010 (UTC)

I'm trying to Diels-Alder react cis-cinnamic acid with pyrrole to form troparil (and similar derivatives). (okay the product is missing a carbon, but I'm still curious -- I suspect the methylene carbon affects the conformation of the 7-membered ring and I wonder what would happen if it was removed. notably dopamine has the amino group 2 carbons away from the phenyl group but in troparil it's 3 carbons away.) Diels-Alder is pretty stereospecific, so yeah. Don't worry my interest in troparil is mostly academic. I work in a drug addictions lab in the medical school (as a lowly work-study undergrad), and I'm thinking it would impress my supervisor if I came up with a theoretically cheaper way to synthesise compounds that cost thousands of dollars per experiment to test each time -- just for the material alone!

(Also I figure practicing wouldn't hurt me since I might have no orgo courses until grad school. I'm also trying to find someone who's willing to supervise my experiment if my reaction conditions aren't too harsh...) John Riemann Soong (talk) 07:29, 4 January 2010 (UTC)

trans-Cinnamic acid is cheaply commercially available, or can be made using aldol or malonic-ester reactions (though I think the yield is often poor--companies probably have patented an improved process). I know many cinnamic-acid derivatives can be photoisomerized trans→cis. That's a cool reaction...it's reversible but it's not an equilibrium (either can be excited by light and undergo isomerization, but you can get reasonable yields of the clearly less-stable cis compound). DMacks (talk) 17:01, 4 January 2010 (UTC)

If you feed D-Phe to Phenylalanine ammonia-lyase, would it make the cis-isomer? Or not really? John Riemann Soong (talk) 22:04, 4 January 2010 (UTC)

Frozen organisms

What's the largest organism that can survive frozen in a block of ice? (My question is open-ended on what minimum survival time is meaningful. Let's make it 2 separate questions: what's the largest organism that can survive frozen in a block of ice for a day; and what's the largest that can survive for a month?) Comet Tuttle (talk) 06:28, 4 January 2010 (UTC)

A number of species of frogs are known to be able to overwinter completely frozen; they alter their blood chemistry right before going into hibernation in such a way that prevents formation of large ice crystals (which would have caused irreversible tissue damage if allowed to form). It is also likely that some species of freshwater fish in the permafrost belt can do the same, as some ponds there do freeze solid (Couldn't find a reference though). Among the warm-blooded, I remember a documentary with Sir David Attenborough showing a hibernating bat with an icicle hanging from it (no kidding!); the bat itself was cold (almost invisible in a thermal scan) but not frozen. If it freezes solid it dies AFAIK. --Dr Dima (talk) 08:45, 4 January 2010 (UTC)

OK, I found the refs I was looking for. Cold-climate fish and insects prevent the formation of large ice crystals by having Antifreeze proteins in their tissues. There is a whole bunch of references in the Antifreeze protein article. --Dr Dima (talk) 09:09, 4 January 2010 (UTC)

Not directly relevant to your question, but I think it is worth noting that viable microorganisms have been extracted from ice at least several hundred thousand years old (and some claimed extractions for millions of years). In addition, at least some bacteria remain metabolically active when imprisoned in ice provided that some form of food source is available such as an adjacent dust grain or concentration of organic impurities. Dragons flight (talk) 09:12, 4 January 2010 (UTC)

That's relevant, too — it sounds like microorganisms might be able to avoid death from cold damage, but larger creatures need antifreeze to live. Thanks! Comet Tuttle (talk) 22:11, 4 January 2010 (UTC)

Using anti-freeze to prevent freezing is different from surviving freezing, though. Imagine Reason (talk) 02:21, 5 January 2010 (UTC)

Yeah, especially if the animal using antifreeze is a dog...they don't seem to survive antifreeze too well :-) Nyttend (talk) 06:08, 5 January 2010 (UTC)

pull of gravity or magnetism or any force

Is it safe to say that no matter how close two objects, particles or any matter comes to each other the attractive or the repulsion forces will never be infinite? 71.100.1.76 (talk) 08:42, 4 January 2010 (UTC)

Yes, that's fair. Infinite force will not actually occur. Formulas that appear to lead to infinities will generally be approximations of reality that aren't actually valid in the vicinity of the expected infinity. Dragons flight (talk) 09:19, 4 January 2010 (UTC)

For the forces to be infinite, the two objects would have to be literally at the exact same position. But as the distances get shorter, the scale on which we're measuring them starts to make quantum mechanical effects very noticable. Objects at the quantum scale don't have a firm position - merely a fuzzy "probability cloud" centered on some point in space. This will prevent them from being positioned a literal zero distance apart because the probability of two objects being at the precise same point is infinity-to-one against - which makes it impossible. Hence no infinite forces occur - even though the math suggests that they might. SteveBaker (talk) 14:12, 4 January 2010 (UTC)

The words "any matter" include matter+antimatter interactions. Can we consider the force which would be needed to reverse a matter+antimatter annihilation that has occurred? Cuddlyable3 (talk) 23:27, 4 January 2010 (UTC)

The thought of antimatter did not occur to me when I asked the question but now thinking about it briefly suggests that mass probably becomes energy in the form of gamma radiation before force can become infinite or perhaps on the road to force becoming infinite. But its past my bedtime. 71.100.1.76 (talk) 01:43, 5 January 2010 (UTC)

In Cuddlyable3's case(Matter Antimatter Reactions), because $dE=\int _{C}F\cdot ds\Rightarrow d^{2}E=F\cdot ds$, so it can be seen that energy can viewed as infinite different forces acting on an object on different points, stressing the infinite. So I think in this case, the resulting force might really be infinite!The Successor of Physics 10:54, 7 January 2010 (UTC)

Frozen citrus fruit?

While travelling halfway across the USA this past week, I accidentally left some clementines in a bag in an unheated vehicle overnight. This morning, I decided to eat two for breakfast, and I found that one was distinctly squishy (so I called it my own Squishy :-) while the other seemed normal; the squishy one is now in the compost, and the normal one in my stomach. Is the nutritional value of clementines damaged when they're frozen whole in this way? What I saw on Google when I looked for "freeze" and "citrus" was generally (1) how to freeze citrus fruits optimally in your freezer, and (2) damage done to orchards by sudden frosts. Nyttend (talk) 14:02, 4 January 2010 (UTC)

If consumed straight after defrosting it would have been OK, just the texture destroyed, but the substances contained in it would have been the same. The cell structure would have been disrupted, and that would lead to rapid deterioration if kept. Perhaps you could have juiced it! Graeme Bartlett (talk) 21:24, 4 January 2010 (UTC)

I'm no expert but some nutrients (vitamins etc) can be be reduced by freezing, but if a piece of fresh fruit is several days/weeks old (even if stored in a coolroom) it will also have a reduction in nutrients. Freezing on the other hand can help preserve these until it is defrosted for consumption. Chemical reactions and growth of mold/fungus & decomposition are all accelerated by higher temperature. As you noticed and Graeme explained, the cell structure is damaged(ice cystals) and it became 'squishy'. Frozen_food#Effects_on_Nutrients has more details. --220.101.28.25 (talk) 03:32, 5 January 2010 (UTC)

Well, I didn't consume it immediately after defrosting — yesterday (the day after it was left in the vehicle), I spent all day in the vehicle with the heat on; after reaching my destination last night, I took it inside, so it had all of yesterday and all of last night to defrost. Thankfully, there was no mold or fungus visible; otherwise, I wouldn't have bothered finding whether it was squishy or not. Nyttend (talk) 04:36, 5 January 2010 (UTC)

LCD TVs and their Manufacturers

I'm curious about these things because I have heard that as far as their screens are concerned, each individual company doesn't make their own, and that pretty much all branded TVs get their screens from one of only 2 or 3 screen manufacturers, then sort of change the peripherals like the box and the remote control and put their own logo on it, then off to the shops with it. Can anyone be more specific on this and/or confirm it?

Effectively, if I've got it right, it would mean that between, for argument's sake, the 700 quid Sony model and the 400 quid Goodmans next to each other on the shelf, both same size, there would be very little difference in the actual viewing quality or life of the product. Lucas 83 14:12, 4 January 2010 (UTC) —Preceding unsigned comment added by Lukerees83 (talk • contribs)

Well, you're right that many brands share component manufacturers. Whether Sony and Goodmans do I couldn't say. My personal recommendation, though, is to find a store that runs a lot of screens side by side and start doing comparisons. Get up close and see if you can spot differences, then back up to your expected viewing distance and see if those differences still exist. If possible, see if the store will dim the lights in the area -- brightly lit stores don't reflect most home viewing environments. Finally, you've got to evaluate how much an incremental improvement is worth -- even if you can spot the difference in the Sony and the Goodmans, there's no objective answer as to whether the "viewing quality" is worth 300 pounds. — Lomn 16:40, 4 January 2010 (UTC)

Also, while there are only a few panel makers, there is more to a TV than the panel. Back-lighting can make a major difference to the resulting quality, as can the decoder. And it's quite possible that the makers perform binning, sending the best panels to premium customers, selling the average ones on the open market, and dumping the remainder to low-cost sweat shops. --Stephan Schulz (talk) 16:54, 4 January 2010 (UTC)

There are so many variables in the shops--screen settings, inputs, lighting--that I don't think it helps much to see the products in real life. Imagine Reason (talk) 02:19, 5 January 2010 (UTC)

Plantain herb

Hi My question is "can any part of Plantain herb be used to treat bedsore?" tahnk you.

Sabboor —Preceding unsigned comment added by Sabboor (talk • contribs) 15:39, 4 January 2010 (UTC)

Sadly, we do not give medical advice of any sort, and so will not answer this question. I note that the Plantago major articles notes that the plant was used as a battlefield field-dressing. This should not be taken as an indication that it is of any use for bed sores. --Tagishsimon (talk) 16:11, 4 January 2010 (UTC)

What people believed about science in earlier times

Hi there, I'm trying to find out what people believed in earlier times about science. For example, I want to know what the average person living in the middle ages thought about reproduction in the biological sense. I mean, how well did the average person understand the qualities of semen and that sex results in pregnancy? What did people back then think of the placenta? What about other body organs, like kidneys, livers, etc?

And then I want to know what the "learned" community at the time thought. Where can I find this information? Thanks.--70.122.123.222 (talk) 17:57, 4 January 2010 (UTC)

At Wikipedia, the article History of science and the category Category:History of science would be a good place to start. Most science disciplines also have articles titled "History of XXXX" where XXXX is the name of the science, for example History of biology. --Jayron32 18:56, 4 January 2010 (UTC)

The general topic you are interested in is what is usually called Medieval medicine. There are lots of books on this, if you want to pursue it further. If you want to know about specific organs, your best bet is to probably run a search like "'medieval medicine' placenta" through Google Books.

In a very brief summary... It's easier to say what the "learned" community thought, because they wrote down what they thought, and the medical and scholarly culture of medieval Europe in particular was heavily, heavily text-based. The basic European "learned" model of the medical body throughout most of what we usually call the Middle Ages is known as Humorism—a model derived from the work of Galen. (European scholars were of the basic idea at this time that the Ancient Greeks and Romans had discovered the real "truth" about science and medicine, and that all further work had been corruptions, and so they went back to these very old models for their knowledge, and did not try to innovate on them, or test them.) Around the 16th century this starts to change and you get a more "sack of guts" view of the human body, characteristic of Vesalius, that we see as being characteristic of the Early Modern period (scientific revolution and all that).

Things were less doctrinaire and more varied in the Islamic world (and more "modern" in many ways). At this time, the Islamic world was the real center of medical development, not Europe. The Islamic physicians thought the European ones were completely barbaric. See Medicine in medieval Islam for more information. --Mr.98 (talk) 18:58, 4 January 2010 (UTC)

And just to follow up on my own comment... there are lots of wonderful books written about Medieval science. It is weird stuff. It does not match up one-to-one with modern scientific concepts very well. If I can recommend a favorite that is easily readable and very rewarding, C.S. Lewis' The Discarded Image (1964) is considered quite a classic even by current scholars of the medieval period. ("Hey," you say, "that's about literature!" Well, yes, and no. One of the main points about really understanding medieval thinking that the categories we use today to delineate literature, science, etc., did not really exist in the same way back then. The medieval scholars saw a synthesis of "the whole organization of their theology, science and history into a single, complex, harmonious mental model of the universe," as Lewis put it.) --Mr.98 (talk) 22:08, 4 January 2010 (UTC)

You can also check out the Mishnah and Talmud articles for relevant dates, but they speak of this -- although it might be difficult to get across the language barrier if you don't read Aramaic, unless you speak to a Talmudic scholar or get an English-version, such as Artscroll. In general, the assertions made about science in general and reproductive medicine in specific seems to be generally accurate and most certainly coincident with the popular ideas of the time. The sages of the Talmud were in frequent debate and discussion with the wise men of the time of Greek civilization, and numerous reference is made to debates regarding the nature of the orbits of the Earth and the Moon. Medicinal information is provided, with most of it being arcane and silly next to modern standards of care -- but that was the popular notion of the time among other civilizations as well. Complete understanding of sperm and egg, or at least male + female portions of a fetus seem to be overt, and the placenta is revealed to have been known to both exist and be associated with the fetus. It cannot be known for sure, but there is no indication that the function of specific organs such as the liver/kidneys were known, although the halachic relevance of such information is dubious, and they may have had an inkling at the time, but the Talmud is not meant to be a science text. DRosenbach ^{(Talk | Contribs)} 14:05, 5 January 2010 (UTC)

Does the body need to "breath" oxygen?

I was watching Avatar (great movie btw), and in the movie the humans can walk around on Pandora (alien planet) without any protective clothing (their skin can be exposed), but they needed to be supplied with oxygen (presumably because the atmosphere has no oxygen). So it got me thinking about what a teacher once told me. He told us that the body needs to be surrounded by oxygen or otherwise you will die. Then some student asked him, "What about when we are in water?!" to which the teacher responded "There's oxygen dissolved in the water!". The point of this lesson was to explain to us why tar and feathering causes death. Because the tar "suffocates" the body. I'm not sure I buy that, I would assume it's because the tar is extremely hot.

But anyway let me ask this, if we were on a distant planet that was 100% nitrogen in its atmosphere composition. Would we be ok walking around naked as long as we had oxygen tanks to let us breathe (and the temperature was adequate as well of course)? ScienceApe (talk) 19:53, 4 January 2010 (UTC)

I'm not entirely sure of the answer, but it sounds like your asking if there are any issues with walking in an environment with no oxygen (i.e. would it damage the external parts of the body e.g. skin). I'm not sure of the answer to that question, so I'll leave it for someone else, but my speculation would be that, assuming the atmosphere is at a survivable temperature and you have an oxygen tank mixed at the correct concentrations, you could survive. I'll now hand over to experts to rip apart my answer :) Regards, --—Cyclonenim | Chat  20:07, 4 January 2010 (UTC)

Well, tar and feathering does not actually kill you. That's kind of the point of it—it is humiliating and unpleasant but it's not fatal. But on to the main question: no, and it sounds like a Goldfinger-derived myth, helpfully perpetuated by a clueless high school teacher. You do need to perspire or you can overheat, and this can be inhibited by coating your body in paint or latex or tar or whatever, but it has nothing to do with lack of exposure to oxygen --Mr.98 (talk) 20:08, 4 January 2010 (UTC)

Oh, and regarding tar and feathering, I'm almost certain that if it does turn out fatal, the cause of death would be shock, but I suppose if the tar permanently covered the mouth and nose of the victim, then it would cause suffocation (i.e no oxygen getting to the cells within the body) and then death. Regards, --—Cyclonenim | Chat  20:12, 4 January 2010 (UTC)

(Edit Conflicts) As far as I am aware from previous reading and can find from initial searching, the answer is, yes we would be OK. Our Human skin article suggests nothing to the contrary, and discussions by relevantly qualified scientists I have heard at Mars Society meetings have assumed that outdoor Martian conditions could be tolerated by use of a contact pressure suit and oxygen helmet, without the need for significant air-skin contact.

Tarring and feathering involves not merely cutting off oxygen to the skin, but also severe skin burning (because the burning-hot material adheres and is very difficult to remove). Nevertheless it is usually intended to cause pain and humiliation, but not necessarily death which, though it can indeed occur due to burning injury and shock, is often incidental. Permanently covering all of the skin with any sealing material may cause a slow buildup of problems by blocking its functions, including "insulation, temperature regulation, sensation, synthesis of vitamin D, and the protection of vitamin B folates" as well as some excretion, but (contrary to the fictional scenario in the film Goldfinger) would not cause rapid incapacitation and death. 87.81.230.195 (talk) 20:17, 4 January 2010 (UTC)

"There's oxygen dissolved in the water!". Generally, yes, but we're talking tens of ppm (per this) as opposed to the concentration of oxygen in the air (around 16% or 160,000 ppm). I'd like to hear your teacher's justification for saying that though the skin needs oxygen in some mysterious way a dissolved oxygen concentration some sixteen thousand times less than that in the air would be enough to sustain life. Homoeopathic oxygen, perhaps? Tonywalton ^Talk 20:47, 4 January 2010 (UTC)

Your teacher was wrong. There is a possibility that after an extended time you might have some sort of skin issue, irritation or bacterial issues (since you are converting the bacterial colony from aerobic to anaerobic). But as far as life is concerned, your teacher was wrong. Tar might block sweat pores in the skin, and a person would then very easily overheat (and the tar is also hot). Ariel. (talk) 21:46, 4 January 2010 (UTC)

Not necessarily that hot. Per http://www.inchem.org/documents/icsc/icsc/eics1415.htm the melting point of coal-tar pitch is from 30C-180C (86F-356F). So a low-melting tar (up to say 50C/120F-ish) isn't even that hot. Even the basic premise ("tar and feathering causes death") that this teacher was trying to teach seems suspect. Tonywalton ^Talk 22:06, 4 January 2010 (UTC)

I have seen (at various times in the past) claims that the skin cannot be completely blocked from oxygen for extended periods. Often, it is in relation to a person having his or her entire body painted. Even though the person could breath, they suffocate. So, I do not disagree that there are intelligent people out there who believe that some skin must be exposed to oxygen at all times. However, there are many anecdotes that counter this argument, such as the Blue Man Group and people with rubber fetishes. It is possible that a person may overheat from an inability to properly sweat, but that doesn't apply if the skin is exposed to moving air that doesn't have oxygen. -- kainaw™ 22:01, 4 January 2010 (UTC)

And there are intelligent people who believe in Fan Death. Ariel. (talk) 22:06, 4 January 2010 (UTC)

Anybody remember the Opportunity Knocks show with the silver-painted muscle man (was it Tony Holland)? He appeared in a Speedo-type cossie, painted all over with silver paint, and Hughie Green made great play on the fact that the performer had to complete his act within three minutes (or some-such) or he would die from overheating due to blocked pores. I wonder if this was once one of those now-debunked pseudo-medical myths (like not putting flowers in a bedroom overnight because they'd "use all the oxygen", swallowed chewing gum "wrapping round your heart and killing you" or "not getting pregnant if you do it standing up"). Tonywalton ^Talk 22:29, 4 January 2010 (UTC)

Wow! I remember that! Well, clearly it made the act MUCH more exciting. If you knew that the guy was in no danger whatever, it would have been a lot less interesting. That show was on at about the same time as the Goldfinger movie - and was probably playing on the same misinformation. At the time of the movie, they made a big point of the fact that the actress actually had a small patch of her skin left un-painted (at the base of her spine - allegedly) so her skin could breathe. That alone raises huge red flags - can the oxygen intake from a small patch on one side of the body somehow travel around to keep the rest of the skin alive? How? It's truly a myth put about to make these entertainments seem much more dangerous than they really are. SteveBaker (talk) 00:22, 6 January 2010 (UTC)

Your teacher was wrong, probably because he or she watched the movie Goldfinger. Uncle Cecil dismissed this myth admirably in 1978, when he wrote, "It is now known that you do not breathe through your skin. You breathe through your mouth and nose." Comet Tuttle (talk) 22:13, 4 January 2010 (UTC)

Do not try the experiment at home or you too may gain a Darwin award. Some paints can be toxic applied to the skin. Here's a 2009 Darwin Award Winner. Dmcq (talk) 00:40, 5 January 2010 (UTC)

The danger is overheating, not 'suffocating'. Mythbusters looked at the 'Goldfinger myth' twice:[7][8]. Fences&Windows 01:28, 5 January 2010 (UTC)

Original research: Most teachers are wrong -- that's because teachers are invariably under-qualified. I'm now in 22nd grade, and I've found qualified professors to be severely outnumbered by nothing too far short of 10:1. DRosenbach ^{(Talk | Contribs)} 14:11, 5 January 2010 (UTC)

The Mythbusters actually tested this "Goldfinger" myth (twice) - and with mixed results. The first time, the victim felt pretty ill rather quickly - but it's not clear whether that was psychosomatic, or a consequence of some material in the gold paint that they used or what. However, the second time, they used a safer latex-based material and there was no problem. So it's pretty clear that the skin doesn't need to breathe...at least it can survive without exposure to the air for many hours at a time without problems. Your teacher's claim that dissolved oxygen in water is what saves a swimmer is just a clever guess - and I'm 100% sure it's wrong. I suggest you ask again but this time mention people who survive quite well swimming in tight-fitting neoprene diving suits for hours at a time...clearly those exclude both air and water from the skin - and they obviously aren't porous to either. IMHO, that statement clinches the argument - although I suppose it's possible that there might be longer term problems if your skin were kept away from the air for days or weeks. Avatar was an excellent movie - I didn't think they made it clear whether the masks were to provide oxygen or to exclude some other toxin...I rather suspect the latter was intended. People who lost their masks didn't gasp for air or turn blue (as you'd expect from oxygen deprivation) - so perhaps that's a reasonable interpretation. I need to see that movie again. SteveBaker (talk) 17:57, 5 January 2010 (UTC)

I seem to recall that the only human who was exposed to the atmosphere regularly was the evil base commander guy, who was so tough he could hold his breath for quite some time. I assumed it was supposed to mean that the air just wasn't rich enough in oxygen or something like that. --Mr.98 (talk) 17:31, 6 January 2010 (UTC)

Unknown animals

I know that this file is some type of screech owl (Megascops sp.) and that this file is a marmot (Marmota sp.), but I do not know what either species is, so if you can identify it for me and tell me, I would be much obliged. --The High Fin Sperm Whale (Talk • Contribs) 21:13, 4 January 2010 (UTC)

I don't know about the owl, but the rodent looks like an alpine marmot to me. Looie496 (talk) 22:26, 4 January 2010 (UTC)

Yes, it looks like an Alpine Marmot, only it lived near E. C. Manning Provincial Park, British Columbia, Canada. Alpine Marmots live in Europe. I think it is a Yellow-bellied marmot, but I could be wrong. And I still don't know about the owl. --The High Fin Sperm Whale (Talk • Contribs) 23:44, 4 January 2010 (UTC)

Those who know him well call him Marmota flaviventris. DRosenbach ^{(Talk | Contribs)} 14:14, 5 January 2010 (UTC)

Is the owl an immature Long-eared owl with its ears flattened? --TammyMoet (talk) 09:40, 5 January 2010 (UTC)

No, it is some type of screech owl. And I am now certain the marmot is a Yellow-bellied marmot Marmota flaviventris. --The High Fin Sperm Whale (Talk • Contribs) 00:00, 6 January 2010 (UTC)

So does anyone know what type of screech-owl it is? --The High Fin Sperm Whale (Talk • Contribs) 18:40, 6 January 2010 (UTC)

Nutrient Deficiencies

Perhaps this would be more appropriate over at the history section, but it's somewhat of a medical question as well. My understanding is that many (poor) Europeans during the Middle Ages didn't have a terribly good diet (though I admit that I was unable to find anything specific on the diet of the Middle Ages). This leads me to believe that they may have been deficient in some nutrients. Specifically, I was over looking at the Iodine Deficiency article, where I saw that this particular deficiency is common in areas that don't eat seafood (and don't iodize their salt), which would seem to describe many European peasants from the Middle Ages. So did these people just manage to live with goiter and the symptoms of other nutrient defficiencies? Or were there diets more balanced than I believe, and they gennerally got enough of whatever nutrients they needed, at least to ward off the worst symptoms? A similar problem seems to exist for people in high latitudes getting enough vitamin D before we started putting it in our milk, or in Eskimos getting enough vitamin C from their diet of animal products. Modern nutritian seems to put a pretty heavy emphasis on getting certain amounts of certain nutrients, and I suspect that many people were not getting all of these nutrients in different time periods and in different parts of the world (and still don't, in some places). So can we still function well enough to get by even if we're nutrient defficient in certain nutrients, or am I wrong about many people having defficiencies in the past (or both)?Buddy431 (talk) 21:21, 4 January 2010 (UTC)

Iodine – Yes, iodine deficiency and goiter were seen during the Middle Ages in Europe, according to the Network for Sustained Elimination of Iodine Deficiency. Goiter was so common that some women were painted with goiters. (http://www.iodinenetwork.net/Resources_Nutrition.htm) Some ancient people used seaweed for goiter. The people did live with goiters, but the main danger was cretinism, when mothers could not obtain enough iodine and the lack of iodine caused the babies to develop cretinism, mental and physical retardation. It is possible to live without iodine; its only known use is for making thyroid hormones.

Vitamin D – The body can make several times more vitamin D than you would find in a pill in just ten minutes out in the sun. There are very few foods that naturally contain vitamin D; like iodine, most vitamin D provided naturally by food comes from seafood. In some parts of the world, vitamin D deficiency has caused rickets in children and osteomalacia in adults.

Vitamin C – The Eskimos did not have to eat plant foods in order to have adequate vitamin C intake. Vitamin C was provided by some kinds of meat in their diets, especially raw meat (http://uclue.com/?xq=1716).

Reference Daily Intake – Not all nutrients must be at RDI levels to prevent deficiency diseases. "In human dietary studies, all obvious symptoms of scurvy previously induced by extremely low vitamin C intake, can be reversed by vitamin C supplementation as small as 10 mg a day" (Vitamin C, Wikipedia). "The uses and recommended daily intake of vitamin C are matters of on-going debate, with RDI ranging from 45 to 95 mg/day" (Vitamin C, Wikipedia). Therefore, the RDI is several times higher than the amount needed to prevent scurvy.

“So can we still function well enough to get by even if we’re nutrient deficient in certain nutrients?” It depends on the severity. It is recommended, for instance, that most people receive at least 1,000 milligrams of calcium a day. Teenagers should have 1,300 milligrams. Of course, we can get by with less calcium (look how many Americans have stopped drinking milk), but a suboptimal intake of calcium is likely responsible for high rates of osteoporosis. Many people are deficient in magnesium. Magnesium is essential to life (it is involved in many enzymes), but the deficiencies that people have are not life-threatening, even if they increase the risk of osteoporosis. “Am I wrong about many people having deficiencies in the past?” No, many people in the past did develop goiter or deficiency diseases due to inadequate nutrient intakes. Many people today continue to develop deficiencies in iodine and vitamin D in parts of the world.75.88.127.44 (talk) 23:13, 4 January 2010 (UTC)

OR aheadI recall a college lecture many years ago about vitamin A. It seems that at the beginning of WWII the British Government decided to see what the required intake of vitamin A was (to work out domestic food rationing levels and requirements for the armed forces). So they took a group of volunteers (conscientious objectors, but genuinely volunteering, I seem to remember) and put them on a diet as completely devoid of vitamin A as possible. At the end of WWII they had detected no deficiency symptoms at all. Of course as the Vitamin A deficiency article says, between ¼ and ½ million children go blind each year due to vitamin A deficiency - the difference being that vitamin A is stored (in the liver - the polar bear liver story is well-known). Adults who have previously had access to enough vitamin A can have stored enough to last for years while if you have never had enough vitamin A you haven't had the opportunity to store any. Tonywalton ^Talk 23:34, 4 January 2010 (UTC)

See also Rickets, which is reputed to have been fairly common in, for example, Britain up to WW2. Consider also that much of the higher child mortality rate in past centuries may have been due to such deficiencies, so the extant adult population was already partially selected from those who had not suffered and died from the worst deficiencies. 87.81.230.195 (talk) 03:44, 5 January 2010 (UTC)

In England, the condition of goitre was so common in one part of the country that it was known as "Derbyshire neck". --TammyMoet (talk) 09:37, 5 January 2010 (UTC)

One point not mentioned above is that deficiency diseases were not always attributed to getting too little of some vitamin, protein or mineral (or the foods they come from, before these nutrients were scientifically named). Sharecroppers in the rural U.S. who lived on a monodiet of corn (maize to the rest of the world) got Pellagra, and the devastating disease was variously attributed to a poison in corn, to too much sun exposure, to toxic atmospheres, to bad hygiene, or to bad heredity page 13 before 20th century controlled experiments disclosed the actual root cause as a nutrient deficiency. It was easier for the financial leaders of the southern society to attribute the killer disease to failure to wash up, or to poor genetic stock, than to failure to provide a varied diet to the poorest workers. In the Middle Ages "God's Will" was a satisfactory explanation for deficiency diseases, along with other nonscientific explanations. A supposed cure for goiter in the Middle Ages was the touch of a King's hand, or the touch of the hand of a dead person, or a toad dying in a sack tied alongside the goiter, or saying a magic phrase in some particular phase of the moon. [9] Iodine became an accepted treatment in the early 19th century. It was thought in the mIddle Ages that goiter might be due to impure water or hard work[10], and it is likely that those with a restricted diet worked hard and drank impure water in many cases. Treatment with seasponge ashes, containing iodine, dated back to the 13th century, but was not widely accepted as the effective remedy it was later seen to be. Edison (talk) 15:41, 5 January 2010 (UTC)

planet surviving being engulf by sun

Earth was said earlier to have possibility to survive being inside the sun. Is this possible for Venus to also survive inside a 5 to 7 billion year sun being taken inside the sun but not being destroy. Tango said Earth could also survive being engulf is this possible for Venus to too.--69.226.43.41 (talk) 21:29, 4 January 2010 (UTC)

Where were these things said? Cuddlyable3 (talk) 23:11, 4 January 2010 (UTC)

• At this if earth do but probably not then venus would be even unlikely. It say only if earth do then venus could have chance.--69.226.34.161 (talk) 01:31, 5 January 2010 (UTC)

If earth can, venus can (more or less), but I'm not convinced that earth can survive. Ariel. (talk) 23:13, 4 January 2010 (UTC)

At issue is the definition of "inside the Sun." The Sun has many layers that do not have extremely distinct boundaries. How may layers down does the Earth have to be before it is considered being "inside" the Sun? -- kainaw™ 01:37, 5 January 2010 (UTC)

Why is there an attractive force between the Moon and the Earth? Bus stop (talk) 01:44, 5 January 2010 (UTC)

Hypotheses non fingo. --Tango (talk) 03:08, 5 January 2010 (UTC)

Please see Gravity for the scientific reasons. If asking from a philosophcal POV, it's there so that we have tides, pretty, or if you prefer romantic, moonlight, and as a side effect also keeps us 'attached' to the suface of the Earth. --220.101.28.25 (talk) 04:00, 5 January 2010 (UTC)

I said there that the Earth wouldn't be instantly destroyed. Chances are it would be destroyed before the Sun shrank again, although there is some evidence to suggest it would survive in a much diminished capacity (no atmosphere, no water, most of the crust probably gone): planets have been found orbiting white dwarfs close enough that they should have been inside the red giant at that stage, suggesting they survived inside their star for a time. There is no qualitative difference between the Earth and Venus in that respect, although Venus being quite a bit closer means its chances of survival are quite a bit less. --Tango (talk) 03:08, 5 January 2010 (UTC)

According to [11] a red giant's envelope has a density of ~0.1 kg / m³, which is about 1/10 the density of air at the surface of the Earth. If that's correct, then an enveloped Earth would experience a drag of order 0.5*v²*(0.1 kg/m³)*pi*(radius of Earth)² ≈ 5.5×10²¹ N, or equivalently a torque of ≈ 8×10³² N-m. It's angular momentum around the sun is ≈ 2.6×10⁴⁰ J-s. So, to order of magnitude, it would take about 3×10⁷ seconds (400 days) for such a drag to rob the Earth of all it's angular momentum. I think this back of the envelope calculation shows that in order for the Earth to "survive" the few million years that the sun will be a red giant, it would have to remain far removed from the sun itself and in a region of space with a density probably less than say ~10 μg / m³. Dragons flight (talk) 07:22, 5 January 2010 (UTC)

The above post can be converted to English by replacing "it's angular" by "its angular" in 2 places. Cuddlyable3 (talk) 21:59, 5 January 2010 (UTC)

PS. For anyone that is curious, the current space the Earth travels in has a density of order 10^-20 kg / m³. Dragons flight (talk) 07:28, 5 January 2010 (UTC)

When a star turns into a red giant it throws off its outer layers, reducing its mass. That would cause planets to move further out. That density figure is presumably an average, so it would be significantly less near the edge. Your back of the envelope calculation also fails to account for the reduction in drag as the orbital velocity slows down - that could be a large factor. Whether those two factors are enough to multiply the survival time by a factor of 1,000,000, I don't know. The evidence for survival is empirical, rather than theoretical, and I haven't looked into it recently so there may be alternative explanations now. --Tango (talk) 21:47, 5 January 2010 (UTC)

I think that you may have confused two distinct scenarios for what happens to Earth following the expansion of the sun. In one scenario, the Earth survives the expansion of the Sun by not being engulfed, an rather by being slowly pushed to a higher orbit as the sun expels 30% of its mass in the process of expanding into a red giant. In this higher orbit, the Earth escapes the drag that would doom it to being engulfed. However, simulations disagree as to which scenario will come true. You can read about it at Risks_to_civilization,_humans_and_planet_Earth#Cosmology_and_space. Someguy1221 (talk) 07:34, 5 January 2010 (UTC)

redshift/blueshift hypothetical

I have a hypothetical question regarding redshift and blueshift of light.

If there was a hypothetical giant mirror that reflected all light, and there was a distant star moving towards the earth, but away from the mirror (if the earth and the mirror are stable with respect to each other), would the reflection show a redshift or a blueshift? Googlemeister (talk) 22:28, 4 January 2010 (UTC)

I assume we are observing the distant mirror from Earth. The image of the approaching star recedes from us so its light will be red-shifted.Cuddlyable3 (talk) 23:09, 4 January 2010 (UTC)

Redshift. I know what you're thinking - that the light eventually travels toward the earth, so if it was emitted directly from the star it would blue shift. But the two situations are not the same. The light leaving behind the star causes the star to speed up toward the earth (conservation of momentum), so the light looses energy, the star gains it. If the light was emitting in front of the star, the star slows down and the light gains energy. Ariel. (talk) 23:11, 4 January 2010 (UTC)

I don't understand Ariel's reasoning. The star emits light in all directions so that does not cause the star to accelerate in any direction. The OP stated that the star is moving towards the Earth. Light is electromagnetic energy that is lost by the star, spreads out and is never regained (except by return of a small amount along the path normal to the mirror). Cuddlyable3 (talk) 02:13, 5 January 2010 (UTC)

The star is accelerating. It just happens to be that it's accelerating the same in both directions, and it balances out. However this has no effect on the light leaving the star, which, from the point of view of earth, is still gaining or loosing energy. You normally think of red/blueshift as being due to the motion of the object (doppler effect). This is not so - light does not change in speed. The light changes color due to change in energy, not due to change in the velocity of the star. The light on one side gives the star energy (as measured from earth), and the light on the other side takes energy. Ariel. (talk) 02:23, 5 January 2010 (UTC)

Ariel no. "Accelerating the same in both directions" is nonsense and I don't know why you keep talking about the star accelerating which it does not do in the OP's scenario. Please read the article about the Doppler effect which is well founded in classical physics but which you seem to want to reject in favour of some weird "change in energy" of light.Cuddlyable3 (talk) 22:20, 5 January 2010 (UTC)

Ariel.'s argument is confusing but I think it makes sense; allow me to rephrase it. Each photon emitted in the direction of the star's motion (in your frame) reduces the star's KE (in your frame) and must therefore carry more energy in your frame than it would in the star's (where it does not carry away KE). Similarly light emitted "backward" must have less energy than "normal". The light emitted in all directions by the star thus shows a continuous variation in energy (and thus color, of course) with direction, and so long as any mirrors involved are stationary in your frame, the energy at which you receive it will be determined entirely by its direction of emission and not by its path to you. --Tardis (talk) 00:04, 6 January 2010 (UTC)

You don't need stars and giant mirrors - you can do this experimentally. Stand near a wall and listen to the Doppler shift from the echo of a passing ambulance siren (the echo, not the siren itself coming towards you). If an ambulance siren isn't available get a friend to run in the appropriate direction shouting "Nee Naa". The fact that the siren (or friend, or star, if you must) itself is moving toward you is irrelevant. Tonywalton ^Talk 23:42, 4 January 2010 (UTC)

Huh? How can motion of the source (siren, friend, star) relative to yourself be irrelevant to showing a Doppler shift? Cuddlyable3 (talk) 02:13, 5 January 2010 (UTC)

It's irrelevant for the doppler shift of the echo. For that, you only need to know the relative motion of the source and whatever the sound is bouncing off (and the relative motion of that thing and you, but the OP said the mirror was at rest wrt Earth). --Tango (talk) 03:13, 5 January 2010 (UTC)

Exactly. Sorry if I wasn't clear. Tonywalton ^Talk 23:08, 5 January 2010 (UTC)

Another way to think about it is to look at the total path length from the source to your eyes. If the total path length is increasing with time, you get a redshift; if it's decreasing, you get a blueshift. -- Coneslayer (talk) 16:36, 5 January 2010 (UTC)

So if the star is moving away from the mirror at speed x, and the mirror is moving away from the observer at speed x, then the resulting redshift would be equal for a star moving away at 2x? Googlemeister (talk) 16:45, 5 January 2010 (UTC)

Yes, I think so. In fact, that situation would be the same as looking at yourself in a mirror that is moving away from you at speed x - you would see yourself redshifted as if your image was moving away from you at 2x. That is, in fact, what you would see - an image of yourself that appears to be moving backwards. Apart from imperfections in the mirror, you wouldn't be able to tell that it wasn't a copy of you moving backwards, so it makes sense that the redshift would be the same. --Tango (talk) 21:51, 5 January 2010 (UTC)

Yes to both. In Googlemeister's scenario the star is stationary relative to the observer. Cuddlyable3 (talk) 22:28, 5 January 2010 (UTC)

January 5

sky colors over a blue stars

This question tends to trick everyone, everyone is having a tough time deciding if the star is blue and the planet have earthlike atmosphere, would the sky still be blue or it would have color of something else. If star is any other color, then the sky is blue that easy if it have earthlike atmosphere , if no atmosphere the sky is black.--69.226.34.161 (talk) 01:36, 5 January 2010 (UTC)

Is there a specific question? -- kainaw™ 01:39, 5 January 2010 (UTC)

I meant if earth was orbiting a blue star what color will the sky be, because the blue star has blue light, people would wonder if a blue star will emit blue light, the sky wouldn't be black at this case.--69.226.34.161 (talk) 02:55, 5 January 2010 (UTC)

Of course a blue star emits blue light, that's what makes it blue... Despite your rather confused description of the problem, I think I understand. You want to know what colour the sky would be for an Earth-like atmosphere of a planet orbiting a blue star. That's simple enough - it would be blue. The colour of the sky is due to Rayleigh scattering. The particles in the air scatter blue light more than they scatter light of longer wavelengths, and it is that scattered light that we see when we look up but not towards the sun. The light from a blue star will be scattered the same way. Blue stars still emit over a wide range of wavelengths, just with the peak nearer the blue end of the spectrum (actually, probably in the UV part of spectrum). More interesting would be the sky of a planet orbiting a red star - red stars emit very little blue light (not none, though), so the sky would look very dark (but still blue - or, at least, bluer than the star itself looks). This is all assuming human eyes - life that evolved on those planets would have eyes that see in the range where their star emits most of its light (just as we do), so people on the blue star planet would actually see the sky as UV (which they would be able to see) and people on the red star planet would probably see the sky as green (since they wouldn't be able to see blue). --Tango (talk) 03:23, 5 January 2010 (UTC)

It's a bad idea to speculate on how life around some other star might evolve. Sure, humans have evolved vision that's a good 'fit' for the brightest part of our sun's spectrum - but plenty of other animals see in the infra-red (Owls and some kinds of snake, for example) while others have evolved to see in the ultra-violet (bees, for example). So we can't conclude that evolution would necessarily drive all life to seeing colors that match that of the peak output of their local star. We truly don't know how (and cannot meaningfully speculate) how these hypothetical aliens might see their sky. SteveBaker (talk) 17:40, 5 January 2010 (UTC)

"It's a bad idea to speculate on how life around some other star might evolve." No, it is not. Speculating about what could be is the driving force of science. Of course, it has to be accompanied with calculation, experimentation and observation (the later two being very difficult is this special case). What has gotten into you? I know you from previous years of posting and providing knowledge and help here but lately you tend to answer questions by something equivalent to "It is not, so it cannot be. Full stop." I am worried. 93.132.156.195 (talk) 17:25, 6 January 2010 (UTC)

As I understand it, animals that see into UV or IR only see very near UV or IR. An O-type main sequence star (which is described as being blue) has a minimum surface temperature of 30000K, which corresponds to a peak wavelength of 100nm - that is Extreme ultraviolet, a long way from the near UV that bees can see. (The upper end of O-type is 52000K, or 56nm peak.) I think it is fair to say that all animals on Earth (with the exception of blind cave dwellers, I suppose) are adapted to where the Sun emits most of its light, the differences are fairly minor. --Tango (talk) 21:09, 5 January 2010 (UTC)

You should also keep in mind that the atmosphere matters. An atmosphere with a large oxygen content, like ours, is fully opaque below about 280 nm. It doesn't matter what is emitted if the life forms can never see it. Dragons flight (talk) 21:23, 5 January 2010 (UTC)

That is an excellent point. --Tango (talk) 21:54, 5 January 2010 (UTC)

Bees see UV out to about 300nm - so that makes perfect sense. They can see all the way to the top of the UV spectrum - as transmitted by the atmosphere. SteveBaker (talk) 00:02, 6 January 2010 (UTC)

Anyone want to add information on bee eyesight to bee? Seems like a useful detail. Dragons flight (talk) 21:28, 5 January 2010 (UTC)

I did a little googling, but didn't find any useful reliable sources, just a few unreliable sources that were enough for me to make an educated guess from. I wouldn't be happy including educated guesses in an article. If someone can find better sources, it would be good to include it in the article. We also have Colour_vision#In_other_animals, that could do with expanding (there is more than one paragraph to say on the subject - it could probably have its own article). --Tango (talk) 21:54, 5 January 2010 (UTC)

It's described in detail in Chapter 8 of Richard Dawkins' Climbing Mount Improbable - which includes a pair of photos of a flower, one in normal light and the other in UV - showing how the flower has an ultraviolet 'target' on it, showing the bees the way to the nectar at the center. His bibliography references: "The Honey Bee" by Gould J.L and Gould C.G, "Bumblebee Economics" by Heinrich, B. Online, you can view Dawkin's lecture to the Royal Institution (you don't get much more prestigious than that!) entitled "The UltraViolet Garden" here. "The Natural History of Pollination" by Michael Proctor, Peter Yeo has a diagram at the top of page 131 that shows that Bee vision uses three color receptors - one in yellow, one in blue and the other in UV - going out to 300nm wavelengths. Also "The Pollination of Flowers" by Proctor and Yeo, Collins, 1973, ISBN 0 00 213178 1 has a section about this - and there is more online stuff here Hopefully, that's more than enough reference for such a well-known fact about bee vision. SteveBaker (talk) 23:51, 5 January 2010 (UTC)

UV stands for ultraviolet, looking at this article it actually means black light. Spectrum drawn shown UV end as more or less black.--69.226.34.161 (talk) 04:10, 5 January 2010 (UTC)

"Black light" is actually a casual non-scientific term used in limited applications for what is more formally called Ultraviolet, not the opposite as you seem to suggest. It's shown as black because we humans cannot see it directly (just as we cannot see Infrared) but many other creatures (for example, Bees) can, so it is not "black" to them and they presumably perceive the coloration of the sky and the rest of the world differently to us. 87.81.230.195 (talk) 15:11, 5 January 2010 (UTC)

It's interesting to note that humans actually can see UV, if you remove the cornea, which normally blocks it for health and safety reasons. We can also see x-rays, to a degree, fuzzily, dangerously, in a dark room, but I believe that's through a different mechanism to our normal vision. --Sean 16:31, 5 January 2010 (UTC)

Of course UV isn't a single color/frequency. It's a band of frequencies. People who have had their cornea(s) removed can see a little way into the 'near' ultraviolet - but not as far as (for example) bees can. My mother had hers removed during cataract surgery - it's important to note that you really don't see any 'new colors' - you still only have red, green and blue sensors - so UV light looks just like a very normal blueish violet color. What is interesting is that flowers that are pollinated by bees have evolved to present certain patterns in UV light that are not there in normal human vision. My mother (being an avid gardener) has noticed odd (and very feint) blue/violet stripes and splotches on some kinds of flowers that she couldn't see before - so there is not doubt that she's seeing some of what a bee sees. SteveBaker (talk) 17:40, 5 January 2010 (UTC)

Since this thread has wandered into speculation about superhuman forms of vision we might revisit the archaic idea that the eye sees by projecting instead of receiving rays. That means that what a colour would look like is defined before one sees it. (This is not nonsense, it is how ray tracing in CGI works. Superman's X-ray spectacles must work this way too.) X-rays have a 4-decade frequency range (3E16 to 3E19 Hz) but AFAIK all medical X-ray photographs are monochrome. What wondrous false-colour images they might show through us! I have read that a British local council once decreed a prohibition against use of X-ray spectacles. Cuddlyable3 (talk) 00:02, 6 January 2010 (UTC)

Would we get interesting false colour images? That would require different types of body tissue/bones to have different variations in their opacity to different frequencies of x-ray. Is that the case? --Tango (talk) 00:20, 6 January 2010 (UTC)

I suspect that is the case. Different target (anode) materials have different characteristic spectral emission and absorption frequencies. Charles Barkla received the 1917 Nobel Prize in Physics for his discovery of the characteristic X-ray line spectra of different elements. Furthermore any diffraction effects, such as from crystal structures, are wavelength dependent. One certainly gets differing X-ray medical images with and without injected radiopaque contrast masterial. Cuddlyable3 (talk) 01:55, 6 January 2010 (UTC)

I don't see what injecting a contrast material has to do with it - that increases the opacity at the one wavelength you are using. I have no idea what it does at other wavelengths. --Tango (talk) 02:30, 6 January 2010 (UTC)

In general, I suspect it wouldn't be very interesting. At low energies there is a lot variation in x-ray cross-sections for different elements (it's the operating principle for energy dispersive X-ray spectroscopy), but at the high energies typically needed for penetrating x-ray scans there isn't much variation. Specifically, the high energy x-rays pretty much just scatter/attenuate in relation to the electron densities they encounter. Electron rich elements (calcium in bones, iodine or barium in x-ray contrasts) are more visible because they have more electrons, but they aren't really fundamentally different colors they way one can distinguish them in light. As one may recall, colors come from exciting electronic transitions that are typically a few eV. Once you start firing penetrating x-rays at 40-50 keV there are no more discrete transitions to excite, since everything is ionizing. Dragons flight (talk) 04:03, 6 January 2010 (UTC)

french spiderman

have they ever commited him? here in the us if they feel u did crime but will get a light settence they commite u instread becausse they can keep u there for a long time. —Preceding unsigned comment added by 67.246.254.35 (talk) 02:17, 5 January 2010 (UTC)

Alain Robert mentions many arrests but no involuntary commitment. I'm not sure your US description is fair but the reference desk is not for such debates. PrimeHunter (talk) 03:22, 5 January 2010 (UTC)

Who is "they"? Psychiatrists commit people, not the justice system. --Tango (talk) 03:25, 5 January 2010 (UTC)

In the U.S., involuntary commitment is a legal procedure, not a medical one. But I would like to see evidence that "they" commit people they think are going to get light sentences. 75.41.110.200 (talk) 05:24, 5 January 2010 (UTC)

The Pacific Gull's huge beak...

As far as I am aware, the Pacific Gull of Australia has the largest beak of any gull (it's almost puffinesque) and looking from the front, the gull appears to have a rather wide and muscular jaw. Now, I recall someone mentioning on here (may not have been on this desk, per se) that this bird has a very powerful bite, as might be expected from any large gull. What I'm curious about here is whether the Pacific Gull has a more powerful bite than other gull species of a similar size (say the Great Black-backed Gull, for example) - can it, say crack bivalves with its jaws that other gulls might have to drop from a height onto rocks/concrete to open? Can it tear flesh more efficiently? Can it carry larger amounts of food in its bill? Or is the size of the thing mainly for 'show' (I'm thinking of how a toucan beaks, whilst enormous and impressive are actually much less powerful than they look like they should be)? Any ideas? I've never personally encountered this gull, nor am I likely to at any time in the foreseeable future. --Kurt Shaped Box (talk) 04:02, 5 January 2010 (UTC)

A larger, thicker beak may protect it from fracture when subjected to greater forces, but strength would derive from larger or more efficient muscles of mastication -- I am unaware, though, of the avian set-up of such muscles. As a frequent science-question-related editor, I'm sure you're aware of this, but for the record, it should be mentioned overtly in the text of the discussion on this point :) DRosenbach ^{(Talk | Contribs)} 14:21, 5 January 2010 (UTC)

Tangentially related - why is there a Journal of Hippocampus but not a Journal of Gull Science? With such specificity in scientific publication, I would think that there should be an authoritative reference periodical for Kurt Shaped Box's various gull-related questions. What is the authoritative gull science reference work? ...is it Wikipedia/the Science Reference Desk?Nimur (talk) 15:07, 5 January 2010 (UTC)

Well, ever since we deleted RD/Seagulls.... — Lomn 16:54, 5 January 2010 (UTC)

If nothing else, you've provoked me to create Hippocampus (journal) -- which I should have done long ago, since my dissertation paper is published there. Looie496 (talk) 17:03, 6 January 2010 (UTC)

Which is more important in the grand scheme of things, would you say - gulls or hippocampi? --Kurt Shaped Box (talk) 22:20, 6 January 2010 (UTC)

Yeah, I'm aware of that DR - though I probably didn't make it clear enough. From looking at pictures of the Pacific Gull, it would appear that it is in fact wider in the face/head than other species of gull, which might be indicative of larger jaw muscles - but it's quite difficult to determine with birds, considering how they can puff up and deflate at will (I wonder what doing that feels like? Goosebumps - but consciously controlled?), significantly changing their apparent size and volume. --Kurt Shaped Box (talk) 02:22, 6 January 2010 (UTC)

Hi! Does anybody know the approximate biting force of a gull? I need it for a science project.

Power Curtain

What is a power curtain. I think they have them as a feature on vehicles.174.3.123.13 (talk) 16:11, 5 January 2010 (UTC)

Interesting...I could not find a single google hit in the top 20 or so that discusses automotive power curtains. The only reference to 'curtain' is in curtain-style air bags, but I hope that comes powered as a standard. Wouldn't be much use if you had to crank it open like rolling a window. DRosenbach ^{(Talk | Contribs)} 17:17, 5 January 2010 (UTC)

I saw several auto-related references in foreign (i.e. not US/UK) classified ads. As such, I expect it's a rough translation or perhaps idiomatic. I don't see overlap between "power curtain" and "power windows", so my best guess is that the two are equivalent. Alternately, it might refer to the partition between driver and passengers on a limo. — Lomn 19:04, 5 January 2010 (UTC)

I believe it's a power-operated side window curtain like the one in this photo. You get them on MPVs in hot countries, but not on small cars. --Heron (talk) 10:18, 6 January 2010 (UTC)

It may be a powered window curtain (or shade) as seen on many luxury vehicles, located on the rear deck to shade the back seat from sun. They extend and retract via motor. From the Google results, it sounds like they are quite failure prone (being electro-mechanical in nature). --Jmeden2000 (talk) 16:44, 6 January 2010 (UTC)

Impreza

What is standard-edition trim?174.3.123.13 (talk) 16:15, 5 January 2010 (UTC)

Note that the WRX STI you've linked is far from what many would consider "standard-edition"; however, you can find the specs of that model (and all others available) at Subaru's website. — Lomn 16:51, 5 January 2010 (UTC)

It says in lede, doesn't it (or is it a "newer" version)?174.3.123.13 (talk) 17:32, 5 January 2010 (UTC)

I just googled it, I didn't click on the article, so it may just be a cached version.174.3.123.13 (talk) 17:33, 5 January 2010 (UTC)

I suppose it's "standard" in that it's a mass-produced model, but the STI is the most expensive trim available (out of about 7, by my count) for the Impreza -- thus, it's not what I think most people would consider a "standard" Impreza. — Lomn 19:01, 5 January 2010 (UTC)

From nothing to electricity

A question purely out of curiosity:

In order to generate current, most power plants rely on some form of heat-generation which drives a steam engine which drives a dynamo which generates the current.

In order to make a dynamo, you need a magnet.

In order to magnetize materials, you need another magnet or a current (to produce an electromagnet which can magnetize the material).

So how did people get from naturally-occurring and presumably rather weak magnets to today's strong magnets? Is it possible to produce a magnet which is stronger than the magnet used to magnetize it (or stronger than the magnet in the dynamo used to produce the current used to magnetize it)? (obviousely the answer is yes, but how was it done? Did it involve large transformer circuits to get a higher current or something?) —Preceding unsigned comment added by 83.134.170.251 (talk) 18:53, 5 January 2010 (UTC)

Spontaneous magnetization. Dauto (talk) 19:08, 5 January 2010 (UTC)

Electric current and more windings. Or do you mean before electromagnets? Percussion —Preceding unsigned comment added by 75.41.110.200 (talk) 19:40, 5 January 2010 (UTC)

There are Lodestones, which are natural magnetic rocks. But actually magnets are usually created by electric currents, not by other magnets. The original magnets (except for Lodestones) were also electromagnets. To get the electricity they used a chemical battery a Voltaic pile, not a dynamo. Also you don't need a strong magnet necessarily to make a lot of electricity - you can also use a larger magnet, or spin it faster. Which will give you enough electricity to make any strength magnet you like. Ariel. (talk) 21:51, 5 January 2010 (UTC)

Just out of interest, big power station generators tend not to contain large permanent magnets. See Excitation (magnetic). Tonywalton ^Talk 23:16, 5 January 2010 (UTC)

Lots of turns of insulated copper wire around an iron horseshoe or other form creates a very strong magnet when a small electric current flows through it, far stronger than any natural magnet. These date back to the 1820's, and the work of William Sturgeon and Joseph Henry. There is no paradox such as the OP described, where only a strong magnet could create another strong magnet. Such an electromagnet can be used to magnetize steel or some alloys of nickel, cobalt and aluminum, or Neodymium to create amazingly strong permanent magnets. The current to power the early strong magnets came from zinc and copper plates dipped in dilute acid. Unmagnetized iron, weighing 59.5 pounds, became a strong electromagnet, capable of lifting 2063 pounds [12], just from the passage of a small electric current through thousands of turns of insulated wire around it. From the work of Michael Faraday, a coil moving past the gap of such an electromagnet has a voltage induced in it, giving the basis of the dynamo. One dynamo can furnish the power for its own coils, with the small amount of residual magnetism left in the iron being sufficient to start up the process when the dynamo starts spinning. By the 1890's the electromagnets used in generators were about 30 times more powerful than Henry's magnet of the 1820's. Electromagnets or field coils in generators today can be made even stronger. The strength of any natural or permanent magnets was of no importance in the development of these powerful electromagnets, nor are powerful permanent magnets needed to make the strong neodymium magnets sold today. Edison (talk) 23:10, 5 January 2010 (UTC)

For example, O +ve, and A1 -ve are rare types.

hi

Human blood group systems#Rare blood types:

A blood type is classified as rare when more than 200 donors have to be screened to find one compatible donor with blood of that type. In the "ABO" system, all blood belongs to one of four major group: A, B, AB, or O. But there are more than two hundred minor blood groups that can complicate blood transfusions. These are known as rare blood types. About one person in 1,000 will inherit a rare blood type. Whereas common blood types are expressed in a letter or two, with maybe a plus or a minus, a fewer number of people express their blood type in an extensive series of letters in addition to their 'ABO' type designation. For example, O +ve, and A1 -ve are rare types.

o+ve is Rare Blood type??????? —Preceding unsigned comment added by 212.77.204.150 (talk) 19:49, 5 January 2010 (UTC)

Formatted the original post for greater clarity. I agree that O +ve seems unlikely to be classified as "rare". Dragons flight (talk) 20:30, 5 January 2010 (UTC)

This wouldn't have anything to do with genetic linkage, would it? John Riemann Soong (talk) 20:46, 5 January 2010 (UTC)

The article was recently changed - I've reverted it. O+ is not a rare blood type, about 30-40% of people have it, depending on country (Blood_type#ABO_and_Rh_distribution_by_country). --Tango (talk) 21:17, 5 January 2010 (UTC)

Why are some metals more conductive than others?

I understand why metals are good conductors (namely a decentralized 'sea' of electrons caused by metallic bonding) but why is Silver, for example, more conductive than Gold? I'm guessing that it's at least partially related to the atoms electron shell structure given that copper, gold and silver are all in the same group but exactly why are some metals more conductive than others? I have't been able to find the answer anywhere I look, any help is much appreciated. —Preceding unsigned comment added by 95.150.243.104 (talk) 21:26, 5 January 2010 (UTC)

The "sea of electrons" model is an idealized version of what happens. In reality, all elements will exist on a continuum between a perfect, ideal "sea of electrons" model, and a perfectly "localized" model, where each atom retains its own electrons. So, every metal features some "localization" character along with the "sea of electrons" character; the better conductors have more "sea of electrons" character. Does that help? --Jayron32 21:57, 5 January 2010 (UTC)

These articles should talk about this topic, but some are better, or more complete than others: Electrical conduction, Classical and quantum conductivity#Classical conductivity, Drude model, Free electron model. (Actually most of those articles are pretty bad, but maybe the terms mentioned will help your find your answer in other places.) Ariel. (talk) 21:59, 5 January 2010 (UTC)

Thank you both very much, that's very helpful! —Preceding unsigned comment added by 95.150.243.104 (talk) 22:48, 5 January 2010 (UTC)

January 6

How the hell do people get AIDS?

While reading the article on AIDS I came across a chart the listed the chances of getting HIV based on a particular type of contact with an infected source. If the person I am having sex with has AIDS, I only have a 5 in 10,000 chance of getting it...and considering that the HIV infection rate in the US is less than 1 percent, it would mean statistically I could have sex with a random person 200,000 times before I get AIDS. I think there is a better way of saying this. Obviously I could get it after one time, but I think that statistically if I have unprotected sex 200 000 times, I would be just as likely to get HIV as not. So...how do people get AIDS??? Is everyone else just getting laid *way* more than I am? XM (talk) 06:50, 6 January 2010 (UTC)

The error in your assumption is that the distribution of HIV-positive people is uniform, when it clearly is not. Certain (cultural/ethnic/income/sexual orientation/age) subsets of any population have infection rates many times higher than the overall average. Conversely, certain subsets have rates many times lower. 218.25.32.210 (talk) 06:56, 6 January 2010 (UTC)

To make an extreme example - you could (probably) have all the unprotected sex you wanted with Mormon Octogenarians in Salt Lake City and never approach the likelihood of contracting HIV that someone in Sub-Saharan Africa has after one encounter. 218.25.32.210 (talk) 06:59, 6 January 2010 (UTC)

Look at it from the point of view of disease propagation. In order to spread HIV only needs to infect, on average, slightly more than one person for every person that it kills. Given that the median time to death for an untreated HIV infection is 10 years, most of which time is asymptomatic, it is not so crazy to think that an HIV+ person can manage to have enough sex to infect at least one other person. Add to that higher infection rates from the (mostly) historical problem of contaminated blood transfusions and the ongoing problem of sharing needles by drug users, and it it is not that hard to see why HIV continues to spread even though it does not do so very easily. There are about 40000 new HIV diagnoses per year in the US. There are also about 450000 Americans known to be living with HIV (according to the CDC). Given a ten-year prognosis, if they were all untreated, HIV/AIDS would have already come close to a standstill since about 1/10 of the known cases would be expected to die each year. So, we've made progress. Hopefully we'll eventually see new infection rates fall as well, but we aren't there yet. Dragons flight (talk) 09:20, 6 January 2010 (UTC)

why 5 in 10,000? Why not just say 1 in 2,000? (or is there some reason we can't reduce the fractions?) 194.221.133.226 (talk) 09:30, 6 January 2010 (UTC)

You can reduce it. It's just that the chart in HIV happened to scale everything in per 10000 event terms. Dragons flight (talk) 10:12, 6 January 2010 (UTC)

I would surmise that the robustness of your immune system has a lot to do with transmission probability. I mean, it's pretty obvious isn't it. :) Vranak (talk) 11:26, 6 January 2010 (UTC)

So this 5:10,000 (1:2,000) chance is per time you have 'normal' unprotected sex. If you do so at an 'average' rate of 2.5 times per week (I believe that's about the rate for humans in their sexually active years) then you're doing this 142 times per year. So your chance of getting the disease is now 1:14 per year. Over 14 years of sexual activity - you odds of getting the disease are close to a certainty. Do this experiment for me. Take two normal 6 sided dice. Roll them and add up the numbers. If it comes up '4' you just got AIDS...now roll them again - if it comes up '4' you get AIDS next year...keep rolling the dice. How many years did you get away with it? Of course, you could easily roll a 4 the first time...bad luck...you might get away your entire sexually active life without ever rolling a '4' but it's not really likely is it? SteveBaker (talk) 14:15, 6 January 2010 (UTC)

Also looking at the source quoted [13] 0.04% rises by a factor of ten-ish if your partner has started developing any symptoms, either of you had genital ulcers or it is male-male intercourse. I guess checking the gender of your partner is the onyl one of these you'll be sure of. The only friend I knew who was confident about the risks being small died in 1997 leaving a three year old daughter. --BozMo talk 14:30, 6 January 2010 (UTC)

To be specific, 1 in 2000 is the reported risk for a male to receive HIV from penis-to-vagina intercourse with an HIV positive woman. That last bit is highly relevant. If you limit your partners and have confidence in their disease-free status, then you can greatly reduce your odds of infection. Of course if you have sex three times a week with a different stranger each time, then your odds of infection go way up. Dragons flight (talk) 14:47, 6 January 2010 (UTC)

Additionally, circumcised males vastly reduce their chances of contracting HIV via sexual transmission because of the reduction of mucous membrane surface area. DRosenbach ^{(Talk | Contribs)} 23:49, 6 January 2010 (UTC)

I think it is important to emphasise that it reduces the chances, it doesn't eliminate them. (I know you didn't say otherwise, but I don't want anyone to misunderstand you.) --Tango (talk) 01:57, 7 January 2010 (UTC)

Properly using a condom of course reduces the chances even more Nil Einne (talk) 05:11, 8 January 2010 (UTC)

Climate Change and work done by Professor Cox at Princeton University USA

Perhaps Peter Robert Cox (apologies if I have the name wrong) of Princeton University USA could look at a global warming problem for me? It involves the spreading of the weight of the earth as we move around in space, our spinning, our magnetic field orbiting our sun. I put the question to Professor Cox, what happens to Earth, when our ice changes to liquid and the magnetic fields change? Where will the equator be? where will the 8 meters (i believe you mentioned as an estimate) of water level be? how many hundreds of millions of we humans will be effected? i.e. thats if we don't start to address the problem that many be no longer then a centry away from happening? When we go into the next iceage, where will the "new ice caps form? ...think thats enough for the moment haha.....have much more though.

Wouldn't the main problem facing the human race be the distribution of excess water as opposed to carbon emissions? first and foremost water distribution across the globe to dry but fertile areas of the land mass to enable the mass planting of forests and crops, that would not otherwise survive without the water. Wouldn't that be the first problem to tackle? By changing the effect of more water in our seas to a plus you then can tackle the continuing effects of carbon emittions through the use of the water? You could also address the sea level by redirecting rivers back inland, the mass closing off of rivers across the globe that flow into the sea (the greenies would hate me, but i'm one myself). Create inland canals, storage areas for water across the globe, redirect human population from the cities to the inland water storage areas. Create towns and cities where the water supply is. Also harvesting sea water from the oceans as the human water supply will lesson the impact of the melting of the icecaps. The more the icecaps melt the more the sun's heat will pentrate the earth,(less reflection) therefore the meltdown of the ice may occur faster then we estimate. I would appreciate it if you could let me know what you think. If you have time you may contact me at <email>. Regards I like you work todate. Barry Harrison <phone> —Preceding unsigned comment added by 203.51.38.97 (talk) 07:29, 6 January 2010 (UTC)

Phone and email removed from public post for the protection of privacy. Dragons flight (talk) 07:40, 6 January 2010 (UTC)

• Hello and welcome to the the Wikipedia Reference Desk. This is a free service intended to help answer visitor questions. Volunteer(s) will be along shortly to attempt to address the questions you asked. However, you should be aware that we do not have any special connection to Peter Cox of Princeton, and we do not generally forward questions to outside parties. In addition, answers to questions will be posted directly on this board and we do not generally provide answers by email or phone. Dragons flight (talk) 07:49, 6 January 2010 (UTC)

• The oceans cover about 70% of the surface of the Earth. If you want to reduce sea level by one meter, you would need to flood all the land to an average depth of more than 2 meters. The Greenland ice cap that will, if completely melted, cause about 7m of sea level rise, now is kilometers thick. What's more, all that extra water is unlikely to end up where you want it. There is no guarantee that now dry areas will receive more water (although some may). On the other hand, despite a higher sea level and likely higher overall precipitation, some areas may dry up further. --Stephan Schulz (talk) 12:26, 6 January 2010 (UTC)

Indeed - we have no connection to Princeton - if Mr Cox happens to be a Ref Desk volunteer (it's hard to tell with all of the psudonyms around here!) then he might answer - but the odds of that are pretty small! Let me break up your many questions to make them easier to address:

1. "what happens to Earth, when our ice changes to liquid and the magnetic fields change?" Firstly, the business of the magnetic field 'flip' is nothing to do with global warming. Many scientists believe we are due for such an event sometime soon because they have historically happened on average once every 300,000 years - and it's been 750,000 years since we last had one. However, the 300,000 years figure is only an average - sometimes the earth goes for millions of years without such a flip - so the probability of it flipping in our lifetimes is not very significant. So the two events are not correlated. However, when the magnetic field flips, it "briefly" (in geological time) turns off much of the earth's protection from solar radiation - which would be "A Bad Thing".
2. "Where will the equator be?" - right where it is now! Our compasses would all point in the opposite direction - but that doesn't affect the path of the earth around the sun or our axial tilt (which determines where the equator is). It's only the magnetic field direction that flips - not the entire planet. All of that water sloshing around also cannot make a difference - the earth is well over a million meters across and the sea level rise is "only" 5 to 20 meters - so this is a negligable change to the shape and balance of the earth - nowhere near enough to make an appreciable change to our orientation with respect to the sun.
3. "where will the 8 meters (i believe you mentioned as an estimate) of water level be?" - everywhere that is currently less than 8 meters above sea level. If you own ocean-front property...well, it's gonna be under 8 meters of water. If you live 100 meters above sea level - then the ocean will be closer - but you're not gonna get wet.
4. "how many hundreds of millions of we humans will be effected?" - That's hard to estimate. One problem is that we don't know the extent of the problem. The number "8 meters" that you are quoting is an estimate. Other estimates range from about 2 meters to about 20 meters. Clearly, the number of people who are affected will vary immensely between those two extremes. However, this word "affected" is a tricky one. When the climate changes, every human on the planet is "affected" somehow. So the answer is "All of us"...the real question is not "How many?" but rather: "To what extent?".
5. "i.e. thats if we don't start to address the problem that many be no longer then a centry away from happening?" - it's already happening. The polar ice is visibly reduced - polar bears are going extinct - glaciers around the world are vanishing. People living near large bodies of ice and snow are experiencing rapidly rising river levels - and will soon be witnessing dramatically reduced river levels when it's all melted. This is happening TODAY. Arguably the disaster that struck New Orleans with hurricane Katrina is at least in part due to global warming because the intensity of hurricanes is worsening.
6. "When we go into the next iceage, where will the "new ice caps form?" - Well, we might have been due for an ice age over the next few thousand years - but it's not gonna happen. Global Warming is not the kind of thing that causes ice ages!
7. "Wouldn't the main problem facing the human race be the distribution of excess water as opposed to carbon emissions?" - well, there are other effects too - that CO2 will dissolve in the oceans forming carbonic acid - so the acidity of the oceans will rise and that will have other deleterious effects. But certainly the most obviously apparent effect will be the rise in ocean levels. But the increased temperature is having other effects too - the migration of animals, the places where temperature-sensitive plants will grow is changing. There are many, many other effects that are not directly related to sea level rise. I very much doubt that we've explored all of the problems we're going to see - the world is just too complex for that.
8. "first and foremost water distribution across the globe to dry but fertile areas of the land mass to enable the mass planting of forests and crops, that would not otherwise survive without the water. Wouldn't that be the first problem to tackle?" - Sadly, no. The water is flowing out of the ice caps into the ocean. The ocean is very salty. When the ocean levels rise, that doesn't increase the amount of fresh water available for watering fertile areas of the world! To the contrary, the inundation by the sea kills off crops and makes it impossible to grow plants close to the water in flatter areas. There aren't many (if any) trees that grow well in salt water.
9. "By changing the effect of more water in our seas to a plus you then can tackle the continuing effects of carbon emittions through the use of the water?" - It's not a "plus" - it can't be changed into a plus. It's a gigantic minus! In fact, the rise in ocean levels results in lighter colored parts of the world being covered by darker colored water - that actually INCREASES the amount of absorption of heat from the sun and accelerates the entire process.
10. "You could also address the sea level by redirecting rivers back inland, the mass closing off of rivers across the globe that flow into the sea (the greenies would hate me, but i'm one myself). Create inland canals, storage areas for water across the globe, redirect human population from the cities to the inland water storage areas. Create towns and cities where the water supply is." - well, rivers flow downhill and empty into the ocean. When the oceans rise by (let's say) 10 meters - that's a lot like lowering the heights of all of the hills and mountains by 10 meters and making them shorter by whatever distance the ocean gets closer. That makes using rivers that much harder. But redirecting a long river is a matter of moving gargantuan amounts of dirt and rock...it's very difficult to do on a large scale. I don't think that's really a viable plan. Besides, the water has to go somewhere - even if humans use it, the waste water has to go somewhere. The amount of water produced by the melting of the ice caps is unbelievably huge - you couldn't remotely come close to digging enough lakes to hold it all!
11. "Also harvesting sea water from the oceans as the human water supply will lesson the impact of the melting of the icecaps." - not by any measurable amount. Again, even a modest 2 meter rise in ocean levels would require us to build (say) 12 meter lakes over half the surface of the land to hold it all - and dumping 12 meters of dirt and rock over the remaining half! It's a totally infeasible way to handle the problem. You have to get a grasp of just how huge the oceans are...they cover 70% of the earth's suface - when that much area increases in depth by even a few meters, the increase in volume is spectacular. The oceans cover 360,000,000 square kilometers - multiply that by 2 meters and you get 7,200,000,000,000,000 cubic meters of water. Seven million CUBIC KILOMETERS. Imagine a cube of water half a mile high by half a mile wide...that's a mind boggling thing...more water than a really REALLY large lake. Now imagine seven million of those. That's how much water we have to get rid of at a minimum. The worst-case estimate is for around a 20 meter rise - which is 70 million cubic kilometers. Digging 70 million vast lakes and redirecting our rivers to fill them is beyond crazy!
12. "The more the icecaps melt the more the sun's heat will pentrate the earth,(less reflection) therefore the meltdown of the ice may occur faster then we estimate." - yes, but scientists who are working on the problem are well aware of that issue. There are others that make matters worse too. Water (like most materials) expands when heated. As the planet warms up, the amount of expansion of the water in the oceans right now is enough to produce massive flooding - even if the ice caps didn't melt. Then there are a bunch of other effects - the possible melting of the deep ocean "methane clathrate" deposits - which would dump a bunch of methane into the atmosphere. Methane is an even worse greenhouse gas than CO2 - so that would make matters MUCH worse!

It's good that you're thinking about this - I wish everyone would do that - and ask questions about the bits they don't understand. SteveBaker (talk) 13:52, 6 January 2010 (UTC)

Regarding point 2, actually if you remove 20 m worth of sea level from Greenland and West Antarctica, the redistribution of mass is expected to shift the Earth's rotation axis about 500 m. Not much compared to the 40000 km circumference, but still very measurable and enough to have secondary effects on the distribution of meltwater. Dragons flight (talk) 14:25, 6 January 2010 (UTC)

Regarding number 6, one of the problems with many models of climate change and global warming is that they predict larger swings between climatic maxima and minima. In simpler terms, while on average the world may be getting warmer, there will likely also be greater variation between the hotter hots and colder colds; so that one symptom of global warming may be some "ice ages" of a few decades or a few centuries, followed in rapid succession by some very hot decades or centuries. Rather than gradual changes of slowly warming up or slowly cooling down, we may anticipate wild swings and unpredictable changes from year to year or decade to decade. The climate-change-deniers like to point at this sort of thing and say "See, you don't know what you are talking about, because you don't know whether its going to be warmer or cooler" Actually, that's kinda the point. In a world with stable atmospheric levels of greenhouse gases, then the system is more predictable. With the rapid changes in atmospheric chemistry we have been experiencing over the past century or so, the system becomes chaotic in ways that make it harder for us to prepare for it. See also Runaway climate change which touches on some of these issues, and also discusses some historical examples of periods in the past when we had wildly variable climate. --Jayron32 18:49, 6 January 2010 (UTC)

Anti nuclear anti bodies

what is anti nuclear anti bodies? —Preceding unsigned comment added by 59.92.141.29 (talk) 07:52, 6 January 2010 (UTC)

See our article Antinuclear antibodies. --Thomprod (talk) 12:35, 6 January 2010 (UTC)

Rice type

Is there a rice or rices that will grow in salt marshes and moderate climate? 71.100.3.13 (talk) 08:06, 6 January 2010 (UTC)

Pokkali Rice grows in salt marshes, but I don't know how warm it needs the climate to be. --Sean 15:32, 6 January 2010 (UTC)

Physics and Chemistry

I'm in a joint physics and math undergraduate program now, but I'm thinking of switching into a joint physics and chemistry progam instead (this program is still primarily intended for physics students). I've done a quick googling of condensed matter physics (which the program intro lists as one of the areas falling within the intersection of physics and physical chemistry), and while it is apparently the most active area of research in physics, most of the work I've found seems to be experimental rather than theoretical, and I'm really only interested in doing theoretical work. But at the same time, it also appears that the same is true in other disciplines of physics, such as particle physics (although this may be due to the ineffectivness of my google-searching). Is it just me, or is there little important theoretical work left to be done in physics? If not, what fields of physics (other than string theory and the like) are active areas of theoretical research, and what sort of research could I look forward to if I went into physics and chemistry? Thanks. —Preceding unsigned comment added by 173.179.59.66 (talk) 09:29, 6 January 2010 (UTC)

From time to time it may seem that physics is pretty much all wrapped up and that "the great advances lie in the tenth decimal place" (anyone got a source for that quote?), but I think it's unlikely. The universe is bound to hit us with some big surprise some time soon. Quantum gravity still needs some work. — PhilHibbs | talk 14:51, 6 January 2010 (UTC)

A A Michelson, Light Waves and their Uses, University of Chicago, 1903. [14]. Michelson presented the quotation _as_ a quotation (that is, he appears to be quoting someone else), but there isn't a definitive source for an older version. "Sixth place of decimals", incidentally. Tevildo (talk) 18:00, 6 January 2010 (UTC)

There is theoretical work done in all areas of physics, and experimental work in nearly all areas. That said, a great deal of the theoretical work gets done by people that would generally be classified as experimentalists because their primary work is to collect new data and only a minor portion of their time goes towards developing the theoretical understanding of that data. True theorists, i.e. people who never manage experiments are relatively less common. My experience would suggest there are probably three or four experimentalists for every pure theorist. And its a distinction that has been muddied in recent years with the advent of computer technologies for theoretical modeling. Someone who designs computer models to predict the properties of new chemical compounds would probably be called a theorist though such a person might be closer to an experimentalist in many ways. There are several reasons that pure theorists are less common. For one it is harder. The easiest experimental projects are little more than exercises in applied technology, where one can produce useful science through the repeated application of straight-forward (though technically challenging) processes. That alone can be enough to justify a career if done well. By contrast, a theorist's career depends on developing a legacy of useful and novel insights. The path to doing that is far less obvious. Secondly, it tends to be easier to justify funding things than funding people (even though people can be considerably cheaper). For example, throwing a million dollars at the characterization of high temperature superconductors seems sure to produce something tangible at the end. By contrast, throwing $100k at a theorist to think about loop quantum gravity may or may not ever be useful. Even at the graduate student level it is much easier for experimental projects to offer financial support to students than for theorists to do so.

Because of such factors as those above, I would say that many students with theoretical leanings still end up getting involved in experimental work. And let's not kid ourselves, there is a lot of theory that can go into experiment design and data analysis if that is what one chooses to do. The kind of people that go into physics theory these days (with some exceptions) tend to be very talented mathematicians who coincidentally tend to be terrible at experimental work. There certainly still is a place for a people with a deep understanding of mathematics and birds-eye view of physics, but its not any easy field to get into or do well at. If you are dropping the math double out of a dislike for math (rather than say a love of chemistry) then you probably wouldn't much like modern theoretical physics anyway since it is extremely oriented towards mathematics.

You are right that condensed matter physics is an active area of research. In part this is because it has a relatively large number of near-term applications, far more so than more basic lines of research, and hence condensed matter can more easily attract funding from commercial interests looking for practical solutions in addition to the general funding available for basic research. Most theory done in condensed matter these days is probably of the computer modeling kind (i.e. predicting and explaining material properties through modeling). Deep theoretical insights, such as BCS theory still occur, but would be relatively rare.

At the intersection of physics and chemistry, in addition to condensed matter (see also physical chemistry, materials science), you also have problems in designing new compounds and synthesis processes (a subset of so-called chemical physics), and also applications to areas like biophysics and medicine with the understanding of cellular processes (you'd need to get involved with biology to go those directions). Dragons flight (talk) 15:17, 6 January 2010 (UTC)

First off, thank you for the swift and detailed response.

Now, I don't have an aversion to math at all, but I found some of the math courses I was taking to be a bit tedious. For instance, I had a class in algebra, dealing with fields and rings and so on, and I really couldn't see how it would have any application in physics, so I decided to drop the math part of my program. Right now I'm either switching into pure physics or phys and chem, and I would appreciate any imput as to which one I should pursue. And at the same time, I'm not reluctant to do experimental work, I just don't want to end up just doing experiments, in a way that detaches me from the real physics. Ideally, I would like to spend most of my time thinking about physics in an armchair with some paper and a pen, rather than filling in experimental holes. I looked into this chemical physics business, and from the wikipedia article it appears that this remains a field with theoretical questions to be probed. But looking at some articles published in chemical physics journals, it seems most of the practitioners are chemists, rather than physicist. Are either of these assements correct? Finally, these pure theorists you mention; are they found in all subfields of physics, or just in string theory, loop quantum gravity, and so on? Much thanks. —Preceding unsigned comment added by 173.179.59.66 (talk) 23:09, 6 January 2010 (UTC)

Well, first the bad news, field theories in the mathematics sense are massively important for cutting edge particle physics and string theory, and to a lesser degree quantum mechanics in general. Take a look at Standard Model and gauge theory. Now, of course, there is a lot of ground in the advanced theory of algebras that physicists never use, but the parts that do get used are essential and can get quite deep. In fact, Edward Witten, a leading string theorist was awarded the Fields Medal (the highest prize in mathematics) for the development of new mathematical techniques and theorems needed to understand string theory.

There are theoretical positions in all areas, but far more in the areas of string theory, particle physics (and its cousin particle astrophysics), quantum mechanics, and general relativity. In large part this is because these are areas that are highly amenable to further advancement through mathematics alone. If you really want to be a paper and pen type of theoretical physicist, then the easiest path is to master the deep mathematics relevant to one or more of the highly theory-inclined specialties. By contrast, areas like biophysics, geophysics, chaotic dynamics, fluid dynamics, and ultra-low temperature physics tend to skew towards experimentalists (though you can find theorists in those areas too). Things like condensed matter, cosmology, and thermodynamics are more intermediate.

With respect to the chemistry, I think chemical physics probably is more chemists than physicists (though certainly not exclusively so), and yes there are avenues for theoretical work. In principle, the foundations of chemistry are entirely described with early twentieth century quantum mechanics. In practice, almost no system involving more than two components can be solved exactly, so there is a lot of computational modeling and theoretical approximations in the hope of making useful predictions. And of course condensed matter added a whole further level of complexity. Being able to predict the properties of substances not yet synthesized is both an art and a science.

Personally, I would recommend figuring out what it is about physics that you love and follow that direction as much as you can. Making a career as a theorist is hard and competitive. Unless you love what you do it is unlikely that you will manage to put in the time and dedication necessary to be really good at it. Maybe chemistry does that for you, and maybe not. Maybe it is the mystery of the universe stuff, and you really should pursue string theory, or cosmology, or something. Or maybe you just like having interesting problems to solve, but don't really care about the field they are in (a not uncommon condition for physicists). In that case, you might consider leaving academia entirely; industries like management consulting actively hire physicists (at BS, MS and PhD levels) as technical problem solvers. It's much more lucrative but still caters to the urge to solve problems. Dragons flight (talk) 03:06, 7 January 2010 (UTC)

So are most physicists required to know a computer language or not? Sagittarian Milky Way (talk) 17:27, 6 January 2010 (UTC)

"Most"? Absolutely. Not all professors do, but it would be quite unusual for a new physics PhD not to be able to program at least within a scripting language like Matlab if not also in a compiled language like C++. Dragons flight (talk) 19:00, 6 January 2010 (UTC)

The article Computer literacy gives a good general account of what is expected. Cuddlyable3 (talk) 21:17, 6 January 2010 (UTC)

Regarding the original question, I strongly recommend taking a graduate level introductory quantum mechanics course before making a final decision, if you can. It's needed for just about any advanced theoretical physics or chemistry, and after taking it you'll have a much better sense of where you want to go. Looie496 (talk) 21:55, 7 January 2010 (UTC)

LMC/SMC Not orbiting Milky Way?

http://www.astronomynow.com/news/n1001/06SMC/

This article claims that "Astronomers have recently discovered that the Magellanic Clouds don’t orbit the Milky Way, but are merely passing through our neighbourhood with an entourage of smaller dwarf galaxies in tow." Can someone point me at the evidence for this please? --TammyMoet (talk) 11:04, 6 January 2010 (UTC)

http://arxiv.org/abs/astro-ph/0703196 Dragons flight (talk) 11:13, 6 January 2010 (UTC)

Thanks for this. From the abstract, though, there seems to be no support for Astronomy Now's assertion. Is there anything else? --TammyMoet (talk) 12:33, 6 January 2010 (UTC)

Sure - it's right there in the very first sentence of the abstract: "Recent proper motion measurements of the Large and Small Magellanic Clouds (LMC and SMC, respectively) by Kallivayalil et al (2006a,b) suggest that the 3D velocities of the Clouds are substantially higher (~100 km/s) than previously estimated and now approach the escape velocity of the Milky Way (MW).". If the Magellanic clouds are moving at anything close to the escape velocity of the Milky Way, they cannot be in orbit around it. Hence they will pass through our Galaxy and causing who-knows-what devastation along the way. Obviously, individual stars in each group will be disrupted in different ways - it could easily be that some of "our" stars will be captured by one or other of the Magellanic clouds - and that some of their stars will be captured by us - and all of the galaxies involved will have their nice symmetrical shapes splattered in all directions - but for sure the Magellanic clouds can't simply be in a nice gentle orbit around the Milky Way if they are moving faster than the escape velocity. But even at close to the escape velocity, there is no chance of a nice, clean orbit. A more appropriate term would be "train wreck" ! SteveBaker (talk) 13:06, 6 January 2010 (UTC)

Thanks Steve, but I still don't see how this means they can't be in orbit around the MW - even if it's a messy, chaotic and rapid orbit, it's still an orbit! And what about these "smaller dwarf galaxies"? What are they? They're not mentioned. I've not managed to find any dwarf galaxies which are recognised as being part of the LMC/SMC system. The SEDS page [15] gives about 4 globulars which may have been associated with the Canis Major dwarf, but doesn't mention any around the Magellanic Clouds. --TammyMoet (talk) 14:46, 6 January 2010 (UTC)

Escape velocity, by definition, means they're not in a periodic (or even pseudo-periodic) orbit. --Tango (talk) 14:51, 6 January 2010 (UTC)

What makes you think they will collide with the Milky Way? While they could have escape velocity towards us and will go through us and escape in the other direction, the abstract doesn't say that's the case and I would have thought it would mention it if it were the case. --Tango (talk) 14:51, 6 January 2010 (UTC)

To clarify, that's the paper with the unexpected measurements showing the LMC/SMC to be near escape velocity for the Milky Way (so possibly unbound). Everything else is probably the consequence of filtering the science through press releases and underqualified science reporters. Dragons flight (talk) 15:00, 6 January 2010 (UTC)

(sighs) I guess you're right there - I've had a good look round and can't see anything giving the Magellanic Clouds any entourage! I'm still confused though. If something is moving greater than escape velocity, that means it will escape the gravitational field of the larger object right? If something is moving slower than escape velocity, that means it will not escape the gravitational field of the larger object right? OK so they may not be orbiting us, but the lower-than-escape-velocity speed should mean they will eventually fall towards us, and be captured? It's interesting to see that many websites still claim they are satellites of the MW. Perhaps they're waiting for measurements which show that the direction of movement is not around, but through. --TammyMoet (talk) 15:13, 6 January 2010 (UTC)

If the speed is lower than escape velocity then they will be in a roughly elliptical orbit. The statement about them not being in orbit is just in the event that the speed is greater than escape velocity. If they are in a (psuedo-)periodic orbit then they are captured, that's what the words means, that doesn't mean they will collide with us, though - that would only be the case if the orbit is so eccentric as to make the perigalacticon (closest approach) less than the sum of the radii of the two galaxies, and I see nothing in the abstract to suggest that is the case. --Tango (talk) 16:08, 6 January 2010 (UTC)

catalytic dehydrogenation

Suppose I have a starting reagent that when dehydrogenated, has thermodynamic stabilisation because of aromaticity or extended conjugation of the product. Are there any selective reagents to facilitate oxidation or hydride transfer? If selectivity isn't a requirement -- e.g. it's a hydrocarbon, will bleach or hydrogen peroxide work? John Riemann Soong (talk) 11:22, 6 January 2010 (UTC)

There are several dehydrogenation reactions (especially easy if product is aromatic, for example cyclohexadiene→benzene; "aromatization" reactions should give you lots of literature hits), but I don't know of good catalytic ones. DMacks (talk) 17:41, 6 January 2010 (UTC)

I'm trying to design a transfer hydrogenation reaction... only I need to work backwards from most literature reactions (most people want to hydrogenate, I want to dehydrogenate). Does catalytic dihydroxylation with osmium tetroxide work with aromatic rings? I was thinking of a cyclodiene-like intermediate, with the expulsion of H2... maybe into a hydride acceptor like cyclooctatetraene. John Riemann Soong (talk) 23:55, 6 January 2010 (UTC)

OsO₄ doesn't easily touch benzene; RuO₄ might (heck, that oxidizes diethyl ether → ethyl acetate quantitatively!). But your whole process is confused by mixing up different types of "oxidation". Inserting oxygen is quite different than removing hydrogen. Searching for "catalytic dehydrogenation" gives many hits, there are many proprietary ways of doing it, which should tell you something about the ease of a novice getting it to work using simple chemistry or reverse-engineering an easy forward reaction. DMacks (talk) 16:49, 7 January 2010 (UTC)

Cursus honorum

Moved to Wikipedia:Reference desk/Humanities. --Stephan Schulz (talk) 13:20, 6 January 2010 (UTC)
The following discussion has been closed. Please do not modify it.
I see in the article cursus honorum there are various sequential steps and positions of public offices. Would it be fair to say these are the following and in this order? Military Tribune Quaestor Aediles Praetor Consul Proconsul Governor Censor Tribune of the Plebs Princeps senatus Magister Equitum (Master of the Horse) - 2nd in command (like a Vice President) Dictator From approximately what time range did this apply?--Doug Coldwell talk 12:53, 6 January 2010 (UTC) In what way is this a science question? Can I suggest you take this to the Humanities reference desk - the people there are much more capable of answering questions of a historical nature. All we're able to tell you is that the people who held these offices evolved from small shrew-like mammals and while in office they fully obeyed ALL of the laws of thermodynamics! SteveBaker (talk) 12:59, 6 January 2010 (UTC) What we can also tell you is that you should read your sources. In particular, Governor: "Though not part of the Cursus Honorum...". Also, a governor is usually a proconsul or a propraetor at the same time - one being a rank, the other a position. Censor: "After a term as consul, the final step in the Cursus Honorum was the office of censor" - which implies that all the later positions are not part of the c.h. In particular, as long as (non-thermodynamic) laws mattered, the plebeian tribune had to be a plebeian, while for quite a while the cursus honorum was reserved to aristocrats. --Stephan Schulz (talk) 13:11, 6 January 2010 (UTC) Yikes!!! I thought I was on the Humanities Desk. My mistake.....--Doug Coldwell talk 13:19, 6 January 2010 (UTC)

Spots on Betelgeuse, or just an imaging artifact?

APOD today has a nice picture of Betelgeuse. The text mentions the two bright spots, but it seems to me that there are bands of brightness across the image, some bands are horizontal and the others are diagonal about 30 degrees clockwise from vertical. Where these two sets of lines overlap, there are the bright spots. So, could the bright spots just be an artifact of the imaging process used? — PhilHibbs | talk 13:21, 6 January 2010 (UTC)

Possible, but highly unlikely. You're talking about an image that's been in the hands of numerous professional astronomers, including those who originally decided to construct the image. I think they'd know to account for imaging artifacts before claiming and publishing results. — Lomn 13:29, 6 January 2010 (UTC)

I agree with Lomn. Optical interferometry is very tricky business and requires considerable processing to get an image. What's more likely is either that the bright bands are an imaging artifact due to the (real) bright spots, or the bright bands are related to a real, but unmodeled, structure of the star. If you look at the journal article, the bottom panel of Figure 8 shows the sorts of artifacts associated with this interferometric image; a single point source would be split up into at least 5 spots with some streaks. The researchers don't just look at the image and decide what's there; they model a bunch of things might be there, subject those models to the same observational artifacts, and compare that to the data... whatever model best reproduces the data is their "answer" for what's on the star. The authors found a 2-spot model to work well, but freely admit that "Although the 2-spot model catches most of Betelgeuse surface brightness complexity and can be considered a fair description of the object spatial brightness distribution, going further requires even smaller and fainter details (as images in Fig. 8 show) thus probably showing the complexity of the star surface." -- Coneslayer (talk) 13:51, 6 January 2010 (UTC)

I see, so it is more likely that the bands are an image artifact caused by the spots than vice versa. Thanks. — PhilHibbs | talk 14:45, 6 January 2010 (UTC)

Decay

How have elements with relatively low half lifes not all decayed by now, considering the earth is 4.5 billion years old and before that no telling how long the elements were floating around in space 98.20.192.49 (talk) 14:02, 6 January 2010 (UTC)

Well, for one thing, you can have an element with a very long half life that decays into an element that has a short half life. The decay of the first maintains a supply of the second. -- Coneslayer (talk) 14:12, 6 January 2010 (UTC)

Similarly, other sources produce radioactive (and non-radioactive) isotopes. Carbon-14, for instance, is primarily generated by cosmic rays entering the atmosphere. — Lomn 14:15, 6 January 2010 (UTC)

Same with tritium which can be created by cosmic rays knocking bits from nitrogen nuclei. Googlemeister (talk) 20:59, 6 January 2010 (UTC)

But he's right; this is the reason that there isn't a lot of Californium in the Earth's crust. Comet Tuttle (talk) 20:43, 6 January 2010 (UTC)

Indeed. There are no transuranic elements with half-lives of more than a few million years (ie. about 1000 less than the age of the Earth) so there is no long-lived isotope that can decay into the shorter-lived ones, which means the shorter-lived ones are simply not found in nature. (There are some very minor exceptions due to very small amounts of those elements with the few million years half-lives surviving and the possibility of atoms increasing their atomic numbers through beta decay, but those just give isotopes in trace amounts.) --Tango (talk) 01:52, 7 January 2010 (UTC)

Muonic matter armour?

Could a stable, super-dense material ever be made of muonic matter or any other exotic atoms? And even if they were unstable, what if the muons were constantly replaced in the material (possibly made of normal matter) by some sort of "muon generator?" Also, is there any other form of exotic matter which might be a candidate?Trevor Loughlin80.2.193.221 (talk) 14:38, 6 January 2010 (UTC)

In any meaningful, grounded-in-science sense, no. There's nothing in the question that doesn't require firkins of handwavium. We also note that muonium behaves quite like hydrogen. — Lomn 15:14, 6 January 2010 (UTC)

It would take about 4×10²² W to generate 1 kg of muons at a rate fast enough to match the decay rate. For those keeping track all of human civilization uses about 1×10¹³ W. Dragons flight (talk) 15:27, 6 January 2010 (UTC)

We might need to work on the efficiency of our muon generator then. Googlemeister (talk) 15:55, 6 January 2010 (UTC)

Dragons flight has calculated a lower limit which assumes 100% efficiency. The lifetime of a muon is about 2 microseconds, which means replacing all of your muons half a million tmies each and every second. The energy equivalent of 1 kg of mass is about 9×10¹⁶ joules. Multiplying those numbers gives you your energy input per second (in watts) — assuming that all of the energy you put in is converted directly to muon mass. If you had access to that kind of energy (equivalent to detonating ten million one-megaton nuclear bombs every second) you'd be far better off pointing it at whatever was attacking you.

Incidentally, if you were able to generate all those muons, the wearer of the armor would almost instantly be incinerated by the heat from their decay. TenOfAllTrades(talk) 23:32, 6 January 2010 (UTC)

What if we make the armour spin around you really fast so the time dilation extends the lifetime? Or find some way to turn existing matter into muons, rather than creating them from raw energy? Or have very short wars? You just aren't being imaginative enough! --Tango (talk) 23:40, 6 January 2010 (UTC)

The energy cost for accelerating the shield up to a speed where time dilation becomes relevant is comparable to the energy cost of constantly replacing the muons. Plus, you're going to bleed horrific amounts of energy through synchrotron radiation. Again, if you had a way of accelerating significant masses to relativistic speeds, you'd be better off pointing them at the enemy. If pigs could fly, we could make flying pigs — but they don't. TenOfAllTrades(talk) 03:46, 7 January 2010 (UTC)

I think the centrifugal force would rip the armour apart long before it it reached relativistic speeds, actually. I was joking - I thought the final idea of having short wars (by which I meant wars of less than a microsecond) made that clear. --Tango (talk) 18:01, 7 January 2010 (UTC)

Flesh covered android?

Whilst the human-like intelligence depicted in the "Terminator" movies is quite a long way off being achieved, would an android covered with tissue engineered living flesh be possible with present day technology? And would this be within the reach of an amateur scientists using home equipment?Trevor Loughlin80.2.193.221 (talk) 14:46, 6 January 2010 (UTC)

Apparantly you can cut a cactus in half and then fasten it back again with a piece of metal, and the cactus still lives. So you could see if you could cover a robot in cacti perhaps. I do not know if you could combine cacti flesh from different cacti. Another possibility would be mould. Or do I mean mold? 78.146.51.13 (talk) 15:38, 6 January 2010 (UTC)

Not possible with current technology. It will probably take another 20-50 years of advances in biotech to get to that stage--not that there is actually any good reason to do it, though. Looie496 (talk) 16:33, 6 January 2010 (UTC)

Covering an android with human flesh seems like it might stall in the institutional review board phase. You would have to provide a pretty convincing reason why this would be a good idea. (If you're working alone in a garage, you can circumvent that kind of bureaucracy, at the expense of the support and organizational expertise that a large research institution provides). Nimur (talk) 17:30, 6 January 2010 (UTC)

Would "I want to build the most realistic sexbot ever - and we can all make billions off of this!" be a good enough reason? :) --Kurt Shaped Box (talk) 22:16, 6 January 2010 (UTC)

Only in Japan. --Tango (talk) 23:42, 6 January 2010 (UTC)

Only? Clarityfiend (talk) 02:28, 7 January 2010 (UTC)

There has been a lot of work on trying to make robots that look "human"—always with plastic flesh, though. The results are impressive though they are well inside the uncanny valley yet. The uncanny alley article has some links to such projects. --Mr.98 (talk) 17:59, 6 January 2010 (UTC)

If you want to use animal or human flesh then you would need the internal organs to keep the flesh alive. Vegetable or fungal flesh would be much more practical, as suggested above. For a fungal-flesh covered android, all you would need to do would be to cover the android in damp bread and let nature take its course. 78.146.51.13 (talk) 19:48, 6 January 2010 (UTC)

Current technology to use animal flesh on an android is not currently possible for the reasons state above, but some of the current test models such as eveR-1 have a pretty decent synthetic flesh. Googlemeister (talk) 20:56, 6 January 2010 (UTC)

This kind of question comes up once in a while in conjunction with the X-men character "Wolvarine" (whose bones have supposedly been replaced with metal). This is essentially the same problem that you are contemplating. The biggest problem is that bones are not simply inert lumps of support structure. They also are the source of new blood cells. Without proper bones - there is no way for blood to work - and without that, no flesh. SteveBaker (talk) 23:37, 6 January 2010 (UTC)

"Wolverine" and his bones weren't replaced, but rather partially coated, with the adamantium. How are we ever going to develop razor wielding super soldiers if we can't even cover the basics??? Of course, the question really is - where do the claws go when they retract? Having them sit on top of the bones of his forearm is ju-u-u-st this side of believable (for a superhero), but how they get through all his wrist bones is a bit tricky (or else his wrists should be about twice as thick as normal). Matt Deres (talk) 17:55, 7 January 2010 (UTC)

Special dreams

While dreaming, it is difficult to impossible to read. I heard rumours that some people can not even see colours in dreams. Mostly, it is difficult to recognize visual details. But then, there are dreams when reading is easy, when you can see and recognise every stroke of each letter. All details are (or seem to be) visible, colours are bright even exalting the waking state. Is there a name for that? 93.132.156.195 (talk) 16:36, 6 January 2010 (UTC)

Maybe Lucid dreaming or dreaming may have info for you. --Jayron32 18:35, 6 January 2010 (UTC)

Not really. Lucid dreaming is something different (being aware that so. is dreaming). While I myself, the most parts I can remember from those dreams, am aware that I am dreaming, the dreaming I described above holds elements especially uncommon to dreams that could mislead to take it for reality even more than common dreaming. 93.132.156.195 (talk) 20:19, 6 January 2010 (UTC)

Not sure of the term, but I have found that I can read in most of my dreams, but the part of the brain that is able to recall what I have read does not seem to work right when dreaming, so is it really considered reading if you can not remember it 15 seconds later? In any case, if a term for this has not yet been coined, perhaps you could write a paper and name the phenomenon after yourself? Googlemeister (talk) 20:53, 6 January 2010 (UTC)

I'd just call it a vivid dream. I used to meditate and visualise a lot when I was groing up and sometimes I used to have such vivid dreams I would remember details from them when trying to recall things that really happened. I sometimes actually found it difficult to say for certain whether a particular memory I had was of a dream or of reality!! This was mostly when I was groing up, it hasn't happened to me for a long time now. Vespine (talk) 23:06, 6 January 2010 (UTC)

Exploding olive oil

Earlier tonight, we finished a glass bottle of olive oil. Because it's prettier, we then refilled it from another, plastic bottle (of olive oil). An hour or two later there was a loud bang, and I went through to discover that the bottle had exploded, blowing the bottom clean off, and with a crack running along one of its corners (it's roughly cuboid-shaped). It wasn't near any sources of heat, and wasn't especially warm to the touch when I checked. What happened?! 94.168.184.16 (talk) 21:06, 6 January 2010 (UTC)

Well that certainly sounds pretty bizarre. About the only thing that I can think of is that the bottle had a knock when it was nearly empty, causing a small crack to develop and that when the bottle was refilled this caused the crack to propagate until failure occurred. You could look at the surface of one of the pieces of the bottle to see if there is any sign of an initial crack. Mikenorton (talk) 21:13, 6 January 2010 (UTC)

The culprit will most likely be either overpressure inside the bottle, or a temperature gradient that the bottle could not handle. From what I understand, olive oil has a high heat required to turn into vapor, so unless you were storing your bottle somewhere hot, like near a fire (you said this was not so), this would not seem likely unless your oil had a significant amount of some contaminant like dry ice (highly unlikely unless you regularly keep your plastic bottle of oil in deep freeze). That leaves a temperature gradient, which seems equally unlikely as that would also most likely involve a source or high (or perhaps low) heat. Only other idea I have is that there was some kind of slow chemical reaction between the oil residue, and the new oil. Honestly, I would hope not, because if I chose to eat both of those oil brands, I would not want that reaction to occur within my stomach. Googlemeister (talk) 21:34, 6 January 2010 (UTC)

Could a mouse have knocked it over? 67.243.1.21 (talk) 22:14, 6 January 2010 (UTC)

This doesn't answer your question but I regularly refill glass oil bottles (not because they are pretty but because I often by large quantitities in plastic bottles or cans and the smaller glass bottles are easier to use) including at least once IIRC an olive oil bottle with olive oil but have never had an explosion yet. I do usually clean and rinse the bottle and then let it dry properly first. Nil Einne (talk) 23:25, 6 January 2010 (UTC)

You said "wasn't especially warm". Does that mean it was warmed (or cooled) by something? Because that could do it. A square bottle might have some stress in it from the way it was manufactured, and maybe you hit it or something which released the stress. Check out Prince Rupert's Drops for a spectacular example of that. Ariel. (talk) 00:32, 7 January 2010 (UTC)

All I can say is that olive trees are revered in Greece and perhaps they and their fruits have some interesting properties as a result of being adapted to rather harsh, arid conditions. Vranak (talk) 11:38, 7 January 2010 (UTC)

It may have been due to temperature differences between the old and new oil, particularly if you kept the old bottle in the fridge and the plastic bottle not in the fridge. It may have been the air in the bottle warming up and expanding. (I do not know if oil changes volume with temperature). Or it may have been due to the glass equivalent of metal fatigue perhaps. See also Thermal shock and Liberty bell. 78.151.131.82 (talk) 21:06, 7 January 2010 (UTC)

butter churning

I watched "Catch me if you can" and was intrigued by the story about a mouse who fell into a pail of creme and churned it into butter so it could escape. It occurred to me, is it possible for a mouse to do that? In other words, what energy input is required to convert 2 liters of creme into butter, and is a mouse capable of supplying sufficient energy to do this before it drowned? For the purpose of this, we can assume a temperature of creme most charitable for the mouse provided it is between 5C and 25C. If this question is too complicated for a decent answer, what would be a good way to determine this experimentally without killing the mouse? Googlemeister (talk) 21:23, 6 January 2010 (UTC)

This isn't a particularly scientific answer but having whipped cream before (IIRC never by hand thankfully) and nearly churned it to butter too I highly doubt it. Particularly since it's likely to get harder as it churns it as the viscosity increases. In fact, I'm not even sure how it will work, all that will happen even if the mouse could do it would likely be a mouse stuck in butter (or more likely nearly butter) since I somewhat doubt the mouse could escape the butter once it is churned. More charitably, the mouse may not need to make butter. The surface tension of whipped cream may be enough for the mouse to escape so it won't have to churn it to butter, although I still doubt it would be possible.Nil Einne (talk) 23:19, 6 January 2010 (UTC)

My recollection of churning butter myself (I only did it once with a hand-cranked rotating barrel contraption - and that was a long time ago) is that its a long and exhausting process - I'm 100% sure a mouse couldn't do it. But there is another major hole in the story. When you churn milk into butter - you don't turn the entire volume of milk into solid butter - rather you separate the fat as butter from the water leaving a rather watery milk called "buttermilk". The butter forms little blobs that you have to skim out of the churn and squeeze to get rid of the remaining liquid. So the mouse (at best) dumps a lump of butter into the bottom of the churn and drowns in the remaining liquid. SteveBaker (talk) 23:26, 6 January 2010 (UTC)

Um, the butter will float not drop to the bottom. Ariel. (talk) 00:28, 7 January 2010 (UTC)

Yeah - just about...it's not very different in density than the buttermilk. But still - it's not one solid lump - you get bunch of loose curds that have to be scooped, drained and squished into a patty. Even a little mouse couldn't climb on it. SteveBaker (talk) 01:29, 7 January 2010 (UTC)

It did sound like one of those happy stories with a moral that has no scientific basis, but not having made butter (or whipped creme) I did not realize how difficult it was. Googlemeister (talk) 14:47, 8 January 2010 (UTC)

Palm Trees in Eastern Coast, USA

Where do palm trees start naturally growing on the US Eastern coast? --Reticuli88 (talk) 21:30, 6 January 2010 (UTC)

OR here, but I have seen them as far north as Norfolk/Virginia Beach, but those could have been planted and not natural, and the ones I saw did not look terribly healthy. Googlemeister (talk) 21:36, 6 January 2010 (UTC)

Palmetto trees grow as far north as Southeastern North Carolina. I'd guess that's about the northern limit. --Jayron32 21:37, 6 January 2010 (UTC)

It could be warmer temperatures due to the Gulf stream. 78.146.51.13 (talk) 23:16, 6 January 2010 (UTC)

Sound of sloshing water in home heating system

A week ago, the outside temperature fell to around 20-30 °F from being 30-40 °F the previous week. The heating system, which works through vents at the bottom of the walls, for my apartment stopped working in the middle of the night. I called my apartment manager, and I used a portable electric heater until the next day, when a repairman came and fixed the heating system. I have no idea what he did exactly since the heating unit is down in the basement, to which I have no access.

Everything seemed to be working fine -- the apartment is warm again -- except now whenever the heating system starts up (that is, when the temperature falls below the thermostat's setpoint), I hear the sound of sloshing water in the walls. The sound of sloshing water stops after a few seconds, but while the heater is running, I occasionally hear sounds that I would describe as perhaps a small brook or stream. I am sure I never used to hear these sounds of water before the heating system failed and was repaired.

Also, this I am not so certain about, but I think that the vents may take longer to get hot than they used to, and that when I touch the vents, the metal does not get as hot as it used to. But unlike the case with the sounds of water, I am not totally sure that the metal is less hot (I think it might be, but I am not sure) (even if the metal is less hot, the apartment is still being heated to the setpoint of the thermostat).

I don't see any water leaking anywhere. What do these sounds of water, which I never used to hear previously, mean? Do I need to be worried that something is wrong?

—Lowellian (reply) 21:34, 6 January 2010 (UTC)

If one has central heating with radiators (where water is pumped around a circuit to radiators in each room) then it's common for the plumber to introduce air to the system when working on it, which produces just the sound you describe. One can easily remove this by bleeding radiators with a special key. But it sounds like you have one of those naff blown-air heating systems popular in north america, so I guess it's air in the heat-exchanger pipes instead (and again it should have a bleed valve). Or it's ghosts. -- Finlay McWalter • Talk 22:33, 6 January 2010 (UTC)

If it's air, is this bad? —Lowellian (reply) 22:36, 6 January 2010 (UTC)

Not in moderation, it's just annoying. At least for the radiator-kind (and surely the other kind) there's a feed from the water main that tops off the water if any escapes (from leaks or plumbing-works), which fills the system up. Here is a page about bleeding radiators and here for here for system valves. But if it's an apartment then you might as well get the apartment complex handyman to do it (it shouldn't need a plumber). -- Finlay McWalter • Talk 22:47, 6 January 2010 (UTC)

You were not clear if you have radiators, or air heat. I'll assume radiators. Air is kinda bad because it can cause a slight amount of rust. But also air prevents the hot water from flowing properly, so the radiators would not be as hot. After service which opens the pipes (I'm going to guess he replaced the water pump) you will need to bleed all the radiators. Then after the system runs for a while (and the dissolved air comes out) you will need to bleed the radiators on the top floors. You need a special radiator key to bleed them, it has a square hole in it, and they are not hard to find, any hardware store should have it. Be aware after you bleed the radiators it takes a while for the pressure to build up again - usually you need a full off/on cycle. You might only be able to bleed half a radiator at a time. I'm very very surprised the service man did not say, or do, anything about it. BTW, if this is a multi-unit apartment, you will have to bleed all the radiators in the whole building to get rid of the noise, also if you don't your apartment will always be hotter than the others. Ariel. (talk) 00:00, 7 January 2010 (UTC)

When you bleed the air out of a radiator with the special key mentioned, air hisses out, then a little stream of water squirts out until you shut the flow off with the key. The system should automatically replenish the water in the room where the furnace is. A radiator that is not full of hot water obviously puts out less heat than one full to the top. Edison (talk) 20:12, 7 January 2010 (UTC)

Life sensors

In Star Trek, the sensors can somehow detect the locations and numbers of living organisms. It can't be by heat or electric fields, because those can both be generated by natural phenomena. Is there any scientific plausibility to this? I'm aware that Star Trek is fiction, but many of the other concepts (phasers, antimatter fuel, etc.) have at least some scientific basis. --75.50.48.130 (talk) 22:13, 6 January 2010 (UTC)

Pheromones? CO2 emissions? The above in conjunction with either of these two? --Kurt Shaped Box (talk) 22:22, 6 January 2010 (UTC)

Real scientists look for the signatures of chemicals associated with life, such as methane on Mars. All that tells you is that there is (probably) life, and maybe how much, but not where, and not what. -- Finlay McWalter • Talk 22:36, 6 January 2010 (UTC)

(ec)These sensors are ridiculously inconsistent, even in-universe. The number of times that sensors detect life on a planet before the Enterprise or Voyager even reach orbit are too numerous to count. Yet, they seem to be totally unable to detect intruders, stow-aways, or others on board the same ship in numerous episodes. Rack it up to poetic license, grab a copy of the Nitpicker's Guide to `Trek, and forget about the details. Nimur (talk) 22:38, 6 January 2010 (UTC)

Telepathy and such work in Star Trek, so maybe the life signs detector is based on the same concept. Ariel. (talk) 23:54, 6 January 2010 (UTC)

StarTrek is about story, plot and characters. The technology is quite blatantly allowed to do whatever the story needs with little regard for science. If it's inconvenient for a character to return to the ship - there will be a transporter interference problem from some randomly named mineral deposits on the planet. If it's convenient to be able to transport someone aboard an enemy vessel, it works - if you wanted to beam a large nuclear weapon onto the enemy ship then you can't because you can't beam through shields or you can't beam at warp speeds...except when you can. Hence it's inconsistent, impractical and frequently impossible. Even the simple stuff like the communicator badges they all wear. Sometimes they have to tap the badge in order to place a call - other times they just speak. Ditto with answering calls. When they speak commands to the computer - it's not always clear that they are definitely talking to it. A system like that would result in a computer that picked up random orders from unintended bits of conversation all the time! But none of this matters because it's not that kind of a SciFi show. SteveBaker (talk) 01:24, 7 January 2010 (UTC)

The weirdest thing with the combadges is that they know who you are about to open a channel to before you say it, since the channel is already open and the intended recipient can hear you say "Picard to Riker" (or whatever). Now, that in itself isn't too strange - we know combadges can read minds otherwise the universal translator could never work - but why bother saying it if the combadge already knows? --Tango (talk) 01:43, 7 January 2010 (UTC)

That's actually not too big of a problem. See Buffer (telecommunication). The combadge could keep a 5-10 second recording, and when it hears a "connect" command, simply replays the recording of "Picard to Riker" over the com channel. Ambiguous commands to the computer are slightly more difficult to explain, but remember that Star Trek computers have highly advanced artificial intelligence systems. If you as an intelligent audience member can tell that the command was intended for the computer, then the AI probably would be able to too. That said, most of the Enterprise is usually run by highly powerful plot devices. -- 128.104.50.40 (talk) 23:16, 7 January 2010 (UTC)

I thought of a buffer but it seems to me that there is no buffer at least over long periods since they seem to respond very fast. In fact sometimes even over small intervals it seems there is no buffer. For example, if you say "Picard to Riker", Riker often seems to respond instantly (Riker here), this wouldn't work if the AI only plays back the message to Riker after you finish saying the Riker. Over longer intervals , I guess perhaps the computer slowly reduces the buffer. I don't know if the artificial intelligence in Star Trek is that great. Sometimes it shows some great ability, but for example it often needs to ask dumb stuff it should be able to guess or know or otherwise asks or specifies too much detail. E.g. if you want a glass of water it needs to ask what temperature and e.g. Data, one of the smartest AIs of all doesn't seem to be able to learn not to overspecify detail. There are better examples but it's been a while since I watched Star Trek. Nil Einne (talk) 00:43, 8 January 2010 (UTC)

There are real life life sign detectors. They are used to detect illegal immigrants hiding in the backs of lorries and work by detecting heartbeats (Google will find you details if you ask nicely). --Tango (talk) 01:43, 7 January 2010 (UTC)

Right, but they are looking for a different kind of aliens on Star Trek, most of the time. The device that the Enterprise is equipped with is called Everything_Sensor :) --Dr Dima (talk) 05:58, 7 January 2010 (UTC)

Why not just use visual cues? You can go with infrared, that's probably the most straightforward. Vranak (talk) 11:35, 7 January 2010 (UTC)

I read somewhere that if you could look closely at them one of the health indicators that move up and down in star trek is labelled 'Blue Cross'. :) Dmcq (talk) 14:07, 7 January 2010 (UTC)

[found it at imdb], it said 'medical insurance remaining. :) Dmcq (talk) 17:53, 7 January 2010 (UTC)

Reacting vicinal diols with formaldehyde hydrate (methanediol)

Or better yet ... methylene chloride ... can I count on the rapidity of intramolecular reactions and the driving force of distilling water to get a dioxy five-membered ring? John Riemann Soong (talk) 23:31, 6 January 2010 (UTC)

Also, all solutions I've seen of formaldehyde have been aqueous... essentially since the diol is acting like a protecting agent, how would side reactions be minimised? Is a solution of formaldehyde in methylene chloride viable, or do you have to use a protic solvent to prevent the formaldehyde from evaporating? John Riemann Soong (talk) 23:38, 6 January 2010 (UTC)

The 40% aqueous solution works. Or also you can use paraformaldehyde (no water, so you do not have as much equilibrium problem). If you really want water-free formaldehyde (either as the gas or dissolved in some other solvent, the usual way is by thermal cracking of paraformaldehyde—heat the solid in a still-pot, the gas comes out and you can bubble it into a cooled solvent, or even directly through your reaction mixture. A more efficient way is to start with dimethyoxymethane. A non-acidic way is to use dibromomethane with a base (S_N2 reactions). Beware, the methylene-acetal protecting group is very hard to remove. DMacks (talk) 16:43, 7 January 2010 (UTC)

January 7

what does antimatter look like?

Having just watched Angels and Demons, I was curious to know what antimatter would actually look like. In the film, CGI effects are used to show antimatter as a shiny, glittery substance. Is this in any way possible, as common sense suggests to me that it would either be black, colourless or invisible? If we could produce enough to be 'visible', what would we see? Also, could strong magnets as used in the film be used to hold it in place so as not to come into contact with matter? —Preceding unsigned comment added by 86.180.35.161 (talk) 01:21, 7 January 2010 (UTC)

I believe antimatter looks identical to ordinary matter. Appearance is determined by the charged particles in a substance and, apart from having all the signs reversed, the charged particles in antimatter are the same as those in ordinary matter, and changing the signs doesn't make any difference. It is certainly true that magnetic (and electric) fields are used to contain antimatter. See Antimatter#Preservation. --Tango (talk) 01:33, 7 January 2010 (UTC)

So put another way, antihydrogen would look like hydrogen. --Mr.98 (talk) 02:29, 7 January 2010 (UTC)

Antimatter looks identical to matter. And magnets will not affect antimatter any more (or any less) than they affect matter. (Magnets will affect a plasma.) Ariel. (talk) 02:44, 7 January 2010 (UTC)

However, the north pole of a matter magnet will attract the north pole of an antimatter magnet because the charges are opposite. --The High Fin Sperm Whale (Talk • Contribs) 04:34, 7 January 2010 (UTC)

That kind of depends on how you define north and south, but you're right on an atomic level the poles are reversed. But it would have no visible effect at a macro scale (unless someone manages to find a monopole). Ariel. (talk) 05:07, 7 January 2010 (UTC)

The charge carriers (positrons rather than electrons) in any electrical currents would have to flow the opposite way to get current in the same direction and therefore magnetic field in the same direction. For example if you had an electromagnet hooked up to a chemical battery, the antimatter version of that setup would cause the opposite magnetic field compared to the identical normal matter version. You would be able to tell that they were opposites if they were allowed to interact with each other. Rckrone (talk) 20:43, 7 January 2010 (UTC)

I think the point Ariel is trying to make is that the "north" and "south" poles are generally identified based on the macroscopic properties of the field. Hence anyone studying an anti-matter magnet is likely to label its north pole as the one that attracts south magnetic poles in other magnets. Such macroscopic labeling would require that the microscopic structure of an anti-matter magnet be spatially inverted relative to a normal magnet, but the microscopic details are generally invisible and need not affect which end of the magnet gets labeled north or south. Dragons flight (talk) 22:18, 7 January 2010 (UTC)

Antimatter in the presence of regular matter would look unusual in that stuff would be annihilating and putting out a huge amount of energy. But if it were contained so that that didn't happen and you were only interacting with it by seeing light reflected off it, it would look like normal matter. Rckrone (talk) 20:51, 7 January 2010 (UTC)

Reminds me of something from, i think, The Feynman Lectures. If you meet an alien who looks just like you and holds out his left hand in greeting—don't shake. He is probably made out of antimatter.—eric 23:32, 7 January 2010 (UTC)

Or your long-lost twin that's in the scouts... --Tango (talk) 02:58, 8 January 2010 (UTC)

duphaston tablet

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis or prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the talk page discussion (if a link has been provided). --Dragons flight (talk) 05:19, 7 January 2010 (UTC)

Virtual Reality?

will that ever exist?Accdude92 (talk to me!) (sign) 14:32, 7 January 2010 (UTC)

Have you read our article on virtual reality? It exists now. The degree to which SF-style VR will be implemented (and the timetable on which it will be implemented) will vary, naturally. — Lomn 14:41, 7 January 2010 (UTC)

The Holodeck article will be relevant, and it has a section of links to "similar technologies". I find it odd that the virtual reality article seems to be all about goggles and gloves, and I haven't found any article whose topic is the type of virtual reality that was hypothesized as "cyberspace" in Neuromancer. (The cyberspace article is about something else.) There's a Virtual retinal display article which is relevant to the Metaverse from Snow Crash. Comet Tuttle (talk) 18:00, 7 January 2010 (UTC)

It does exist - it's just a matter of degree. For example - in an advanced commercial flight simulator (especially at night) - it's very hard indeed to tell that you aren't "really there" - absolutely everything you can do, see, feel or hear inside an airliner's cockpit during more or less normal flight is simulated with close to perfect fidelity. However, the "free roaming" variety of VR where you're not strapped into a virtual vehicle of some kind imposes some extremely hard technical issues. The "goggles and gloves" issues can mostly be resolved. But the inability to be impeded by obstacles and the inability to walk around freely in the virtual world with the correct amount of inertia being applied to your body are both exceedingly tough problems to crack. SteveBaker (talk) 18:04, 7 January 2010 (UTC)

I would expect the walking anywhere problem but I would have guessed that the brain would have adapted to overlook the lack of inertia part. The brain is good at selectively ignoring part of its inputs. I thought that was part of the explanation of the flight simulator's limited motion appearing so real. 75.41.110.200 (talk) 22:03, 7 January 2010 (UTC)

Fronts

Why do fronts usher windy weather? How (without using a tv or anything, just by being outside) do you know when a front is on top of you? and why is it not windy when it is over you?Accdude92 (talk to me!) (sign) 18:01, 7 January 2010 (UTC)

As I understand it: A weather front is the boundary between two air masses of different densities. When you have two gases (or liquids) of different densities next to each other and are either moving or pushing each other, you get lots of instabilities (e.g. like Rayleigh–Taylor instability, or Kelvin–Helmholtz instability, or lots of other types), which produce all sorts of turbulence. That's your wind, in part. When you are no longer on the boundary line, you are no longer on that border line that is producing all of those instabilities (winds). As for how you would know if one is on top of you... I'm not sure you can do that without having some knowledge of the weather system as a whole. That is, you'd need to know the air pressure/temperature of a number of different sites, in order to say, "oh, there are two different bodies coming through here." Systemic weather knowledge as a whole generally relies on having more than just local weather information. That being said, some types of fronts are fairly obvious by the weird cloud patterns they produce, like a Derecho. --Mr.98 (talk) 18:25, 7 January 2010 (UTC)

(EC with above). Read Weather front for more information, but to distill it down to the basics, a weather front is the interface between two dissimilar bodies of air, usually a warm airmass meeting a cold airmass in some fashion. When airmasses of two different temperatures colide, several things happen:

• They generate convection currents, as the warm air rises over the cold air, and the cold air sinks below the warm air. The sinking, cold air generates high pressure at the surface (pressing down) and the rising warm air generates low pressure at the surface ("sucking" away). If you have two areas at a different air pressure, the air will move along the ground between the two of them, from the high towards the low, in an attempt to equalize the pressure. Hence "wind".
• Warm air has a higher dew point than cold air does; thus it has a higher "carrying capacity" with regards to water vapor. Just like when you breath hot breath on a cold glass, and you get little water droplets, when the hot moist air meets the cold, dry air, lots of little water drops form. Hence "clouds" and "rain"

These two effects happen any time you have warm and cold air meeting. The difference between a "warm front" and "cold front" and "stationary front" comes down to which air mass is doing the "pushing" and which airmass is being "pushed". If the warm is moving into the cold, it's a "warm front". If the cold moves into the warm, its a "cold front". Some more reading along these lines can be found at Surface weather analysis and, depending on how advanced you want to get, Synoptic scale meteorology. --Jayron32 18:29, 7 January 2010 (UTC)

There are several things you can look for that will tell you a front is passing you

• The Pressure drops and then rises again
• The wind shifts direction
• The wind becomes gusty and then turns calmer again
• The temperature changes
• Humidity changes
• Usually there is some precipitation

Dauto (talk) 19:19, 7 January 2010 (UTC)

The barometer was once the most important weather diagnostic and predictive tool, because it detected pressure changes associated with incident fronts and changing airmasses. In today's technological world of interconnected weather stations, NEXRAD doppler RADAR, and GOES weather satellites, we have other ways to predict and map weather changes and front systems; but you can still do a pretty good job predicting short-term weather with nothing but a barometer. Nimur (talk) 21:42, 7 January 2010 (UTC)

Look out your window. If you live in the plains you will often have a good long view of the approaching clouds associated with the front. 75.41.110.200 (talk) 22:00, 7 January 2010 (UTC)

How do I change my ocular dominance?

Subject. HitmanNumber86 (talk) 18:04, 7 January 2010 (UTC)

Answer: Training. --Jayron32 18:18, 7 January 2010 (UTC)

Are there exercises I can do, or chemicals I can use? By the way, cite your sources, please. —Preceding unsigned comment added by HitmanNumber86 (talk • contribs) 18:27, 7 January 2010 (UTC)

Wear an eyepatch? 78.151.131.82 (talk) 20:50, 7 January 2010 (UTC)

Poke out your dominant eye? I'm not an expert but I'd say it's not possible to change it, unless maybe you are younger then 5. The visual cortex is one of the best studied areas of the brain so there probably is a good answer somewhere. I don't think the eye patch will work either. One thing I heard recently is that when a baby is discovered to have a lazy eye (Amblyopia), they put a patch on the strong eye. Unsurprisingly the weak eye's development gets strengthened and after some time it can be made to catch up and become pretty much "normal". However, surprisingly, to me at least, patching the strong eye does NOT weaken its development, even if the patch is worn for extended periods, like months, during early development. Vespine (talk) 21:18, 7 January 2010 (UTC)

This actually falls into the category of medical advice (intentionally or not), and we shouldn't be giving answers. Looie496 (talk) 21:40, 7 January 2010 (UTC)

I disagree. I wouldn't consider not liking your eye dominance to be a medical condition. --Tango (talk) 22:40, 7 January 2010 (UTC)

I wonder whether this might be similar to changing your hand dominess or Handedness which may be possible, but is problematic [16]. If you believe the " Consulting and Information Center for Left-handers and Converted Left-handers" extremely so [17] Nil Einne (talk) 00:25, 8 January 2010 (UTC)

Large Hadron Collider question

I just read some of Eric Johnson's document, The Black Hole Case: The Injunction Against the End of the World, and it is quite an insightful text, but I'm left wondering, if this machine is deemed unsafe somehow or another, who's got the power to shut it down? –Juliancolton | ^Talk 19:35, 7 January 2010 (UTC)

The chances of that happening is somewhere between zip and nill. Dauto (talk) 20:25, 7 January 2010 (UTC)

Still, the question of jurisdiction is an interesting one. --Mr.98 (talk) 23:11, 7 January 2010 (UTC)

Since the Large Hadron Collider is astride the French-Swiss border, part is within the jurisdiction of France and part within Switzerland, so I'm going to say "the authorities" in either country. Comet Tuttle (talk) 20:29, 7 January 2010 (UTC)

The CERN article says "As an international facility, the CERN sites are officially under neither Swiss nor French jurisdiction". It doesn't really explain what is the pertinent jurisdiction both for spectacular-death-by-physics matters, but also more humdrum stuff like office punchups and accidents in the workplace. -- Finlay McWalter • Talk 20:44, 7 January 2010 (UTC)

Thanks all. –Juliancolton | ^Talk 20:55, 7 January 2010 (UTC)

Here is a relevant quote from 2007, regarding the protocols that make CERN exist, by the CERN legal council:

The Protocol also grants us [CERN] immunity from jurisdiction of the national courts, to ensure our independence from individual Member States. Mind you, this doesn't mean we operate in some kind of legal vacuum: the Protocol requires that CERN settle its disputes by other means. This is why claims by the members of our personnel against the Organization should be submitted to the Administrative Tribunal of the International Labour Organization, and why conflicts between CERN and its contractors are decided not by the national courts but by independent experts appointed by the disputing parties.

...which seems like quite a legal tangle. --Mr.98 (talk) 23:11, 7 January 2010 (UTC)

At a political level, rather than a judicial one, I assume the member states have the authority to withdraw their financial support which would effectively shut it down. I imagine one could also play some legal chicanery such as the host nations asserting jurisdiction over the power lines that feed the site even if they don't have jurisdiction over the site itself. But to the legal question of what external party has the authority to order a work stoppage? I think the answer might be none. Dragons flight (talk) 23:26, 7 January 2010 (UTC)

Nice find, Mr.98. Since they have been set up as accountable to nobody, they are a sovereign; so I think the way to settle this matter is going to have to be an invasion by force, though of course the scientists have a supercollider as the main weapon on their side. Comet Tuttle (talk) 23:47, 7 January 2010 (UTC)

Actually Mr.98's note about lack of jurisdiction is already mentioned in the PDF that the OP cited in the first place. Comet Tuttle (talk) 23:52, 7 January 2010 (UTC)

Yes, looking at it closer, it goes over the jurisdictional issues pretty clearly. Page 49 of the PDF. --Mr.98 (talk) 00:07, 8 January 2010 (UTC)

I presume if another country is convinced it would destroy the world, they would also consider they are entilted to destroy it if diplomatic efforts fail. This technically means any soveign country but it seems likely only those who have a resonably chance of attacking and destroying it like the US, China, Russia, probably India and perhaps Pakistan, Israel and Japan (if they decide to remove their inability to launch a war and perhaps develop nuclear weapon) should be considered. Do note I've purposely excluded those from the EU who likely have an ability to shut it down without resorting to war. Presuming they are accurate in their belief, it seems likely such an attack would be considered justified under international law although this may not be enough to stop a counter attack. In reality, it seems rather unlikely any country would have to resort to such actions although the threat of war may or not be a useful part of their response Nil Einne (talk) 00:34, 8 January 2010 (UTC)

Did you say unlikely? I think that's an understatement. As I said above the chances are somewhere between zip and nill. Dauto (talk) 01:28, 8 January 2010 (UTC)

I think Nil Einne meaned it is unlikely a country would have to take military action in order to stop the LHC (because there are better ways to do it), not that it is unlikely the LHC needs to be stopped (which is, indeed, an understatement). --Tango (talk) 03:01, 8 January 2010 (UTC)

Well I think the chance a country will need to take military action even if it is necessary to stop the LHC is probably close to zip and nill too (it's not as if we're talking about North Korea here) which may have been what Dauto was saying. However it does illustrate a point. These countries by having the ability to take military action do have the power to shut it down since however they do it, they will be able to shut it down if they really feel it's necessary Nil Einne (talk) 05:07, 8 January 2010 (UTC)

Plastic bowl used in microwave

A nervous friend placed an old plastic bowl in a microwave and heated food.

When removed, the bowl was found to be entirely unaffected. Nonetheless, it was thrown away as a precaution.

She's worried that the bowl may have released harmful fumes that could continue to be dangerous in the future. Assuming the microwave is carefully wiped out, is there really any ongoing danger from future cooking? --Dweller (talk) 20:02, 7 January 2010 (UTC)

Your friend may have heard about the potential long term risk (a pretty low risk) of using plastics with certain carcinogenic plasticisers in contact with food. For this reason it's a good idea to use either pyrex or microwave safe cookware in the microwave. But the "danger" associated with a single use is negligible (and entirely taken by whomever ate the food) and there's no deadly cloud of killer gas lurking anywhere. If your friend had set the plastic bowl on fire and sat in the room while it burned down, that'd maybe carry the risk of smoking a few cigarettes. So no. -- Finlay McWalter • Talk 20:26, 7 January 2010 (UTC)

Could a knowledgeable editor add a discussion about this to our article section Microwave oven#Hazards? I hear a lot about this sort of concern — specifically, that molecules of some sort of biologically harmful plastic will leach into the food — but the only mention in our article is a concern that the plastic will melt. Comet Tuttle (talk) 20:43, 7 January 2010 (UTC)

Let me supply a link, instead of just jabbering: a Harvard Medical School article that discusses "microwave-safe" containers, and advises us against microwaving plastic wrap, water bottles, and several other plastic containers, because of concern about leaching the plastic into the food. Comet Tuttle (talk) 20:50, 7 January 2010 (UTC)

Aqua Amino: "An energised vortex implosion" | Clean up your amino acid loading bays | Restore water to its original crystal structure

Today I bought this bottle of water at a leading chain-store here in South Africa, but I'm highly suspicious of quackery here, so much so that I think our regulatory bodies should maybe take this product down. It's called "Aqua Amino" [18] and appears as a bottle of mineral water, but on the bottle it makes several extremely interesting claims:

• How the process works:

Your DNA provides "loading bays" in your cells where nutrition is 'offloaded' to feed the cell.
The problem is, these loading bays get clogged up until they simply shut down.
Aqua Amino works at DNA level thereby providing your DNA with an optimal blue print to clean up your amino acid loading bays and enable effective amino acid delivery.

The result is a vast improvement to your daily health and renewed levels of vitality.
By allowing your nutrition system to be more efficient, your natural immune system operates at a higher level, providing near-perfect defense against impurities, viruses and bacteria.

• Before and After photo of the water

Aqua Amino is bottled at source in the Magaliesberg Mountains. Its purity is absolute but what sets it apart from other mineral waters is the gara system, a molecular mechanism that creates an energised vortex implosion. This implosion restores water to its original crystal structure, creating 'forgotten water'. The difference is clear, as shown in these pictuers that were taken at the E.F. Braun Wasserkristalle laboratory in Switzerland.

Does any of this sound legit? Rfwoolf (talk) 21:24, 7 January 2010 (UTC)

Not a drop of it. -- Finlay McWalter • Talk 21:29, 7 January 2010 (UTC)

Amazing stuff. Cuddlyable3 (talk) 21:47, 7 January 2010 (UTC)

Sounds like they're on about water memory, sorta. -- Finlay McWalter • Talk 22:04, 7 January 2010 (UTC)

To expand: water isn't a crystal, if you couldn't metabolise amino acids you'd die, if you drank something and it could interact with your (carefully husbanded) DNA you'd die, drinking water won't vastly improve your health unless you're dying of thirst, your immune system isn't materially helped by drinking anything (bar fixing obvious clinically-significant deficiencies), and drinking water won't give you "near-perfect defense" against anything. And this stuff is somehow "pure" yet also contains this impossible nanotechnological wonderstuff. -- Finlay McWalter • Talk 21:55, 7 January 2010 (UTC)

I can't find anything about a "gara treatment", so it's likely that they made it up on the spot. However, searching for "energized vortex implosion" returns this and several other quack products, leading me to belive that "vortex" and "implosion" are pretty common pseudoscientific words, that may have some specific meaning. (anyone who knows more care to elaborate?). The site linked above does reference what is undeniebly water memory. This is decidedly NOT spam. You should not by any of these products, from this or any other site. Buddy431 (talk) 22:32, 7 January 2010 (UTC)

Of those claims, only two are even potentially correct:

1. Aqua Amino is bottled at source in the Magaliesberg Mountains.
2. these pictures...were taken at the E.F. Braun Wasserkristalle laboratory in Switzerland.

Everything else is clear nonsense. (And the ice pictures don't demonstrate anything; they're just pictures of different-sized ice crystals.) TenOfAllTrades(talk) 22:37, 7 January 2010 (UTC)

E.F.Braun appears simply to be someone who takes rather nice microphotographs of ice crystals - http://www.wasserkristall.ch/ -- Finlay McWalter • Talk 22:41, 7 January 2010 (UTC)

I remember seeing a product with concentrated distilled water in it. Ariel. (talk) 23:13, 7 January 2010 (UTC)

I'm darned if I know what this paper is using? -- Finlay McWalter • Talk 23:17, 7 January 2010 (UTC)

Similar pseudoscience to Penta Water. Fences&Windows 23:55, 7 January 2010 (UTC)

Crystal water at room temperature? sounds like Ice-nine to me :) Dmcq (talk) 10:44, 8 January 2010 (UTC)

Why do cold fingers get pruney?

I notice that when it's very cold outside, my hands look as if I've taken a very long bath. Why do fingers get pruney skin from cold exposure? --70.167.58.6 (talk) 23:09, 7 January 2010 (UTC)

There is a myth that pruney fingers after a bath is due to water being absorbed into the skin. This is not so, see: Wrinkle_(skin)#Pruney_fingers. So maybe cold is causing the same reaction in your fingers. Ariel. (talk) 23:29, 7 January 2010 (UTC)

That section talks about vasoconstriction, which does, indeed, happen in the cold, so that makes sense. --Tango (talk) 01:23, 8 January 2010 (UTC)

in vitro use of enzymes

I'm trying to see whether I can use tyrosine hydroxylase in vitro. I've looked up some of the literature and apparently I need to activate it with phosphorylating agents like various MAP proteins -- but apparently they're talking about E. coli transfection, and not like, running your enzyme on reflux in a test tube or something? John Riemann Soong (talk) 23:49, 7 January 2010 (UTC)

January 8

californium

The section Californium#Characteristics says: "One microgram spontaneously emits 2,314 million neutrons per second"

Is that 2.314 million per second, or 2.314 billion (Short scale) per second? (Comma is such a strange symbol to use for a decimal point.) And incidentally the ref it points to does not say. Ariel. (talk) 00:37, 8 January 2010 (UTC)

It should be 2.314 million per the ref on the top of page 3. Fixed in the article. Dragons flight (talk) 00:42, 8 January 2010 (UTC)

Chewing medicine capsules

Bottles of medicine capsules always say not to chew the capsules, but to swallow them whole. What would happen if one were chewed: would it be useless? Don't take this as a request for medical advice; I can't imagine why I wouldn't follow the directions and swallow them, even if everyone here says that it would help to chew them. Nyttend (talk) 00:56, 8 January 2010 (UTC)

I think the main problem is that you would get the medicine into your bloodstream too quickly. The capsules are designed to release the drug at a certain rate. If you increase that rate, you may be risk of overdose, but you'll also be at risk of the drug level in your blood dropping too low - when you take a pill every 4 hours that should maintain the level in your system within certain bounds, if you chew it you'll get a big spike when you take it and then it will drop really low until you take the next one. --Tango (talk) 01:04, 8 January 2010 (UTC)

Because of the Enteric coating. Ariel. (talk) 01:16, 8 January 2010 (UTC)

They may also release the drug too early, which could render it useless (eg. a drug that is inactivated by hydrochloric acid needs to be protected as it passes through the stomach). --Carnildo (talk)

Ah, yeah; at one time I was taking two medicines, and the doctor told me that I could take one (which came in capsule form) at virtually any time in a day because it released slowly, while I had to take the other one (a tablet) at specific times to ensure that I had proper levels. Nyttend (talk) 02:10, 8 January 2010 (UTC)

When you say you could take it at any time, did it need to be the same time every day? If you take it significantly less than 24 hours after the last one (assuming it was one a day) you would still have too much in your system even if it was releasing slowly, and vice versa if it significantly more than 24 hours after the last one. Issues with when you a take a drug are usually to do with whether or not you need food in your stomach when you take it. --Tango (talk) 03:24, 8 January 2010 (UTC)

I am sure most capsules will have bad taste. You tend to throw up weird testing substances before you can chew and swallow completely. manya (talk) 04:18, 8 January 2010 (UTC)

(OR) I once chewed a Tylenol Extra Strength Geltab and my mouth went numb with a horrible taste for about an hour and a half. It seemed as though the gel from the capsule couldn't be washed from the skin in my mouth. —Preceding unsigned comment added by 99.226.164.154 (talk) 14:59, 8 January 2010 (UTC)

Bacteria and Human feces

Does human feces have bacteria in it when push-out? Or is it still fresh when going to the sewage? And could you die/get sick if you ate it? —Preceding unsigned comment added by RadioActive697 (talk • contribs) 05:00, 8 January 2010 (UTC)

See coprophagia. Dismas|^(talk) 05:29, 8 January 2010 (UTC)

And as for the bacteria... see gut flora. Feces is nearly 60% bacteria. Eww. And it's of note that even if the bacteria weren't dangerous to eat (which it is), feces is a major vector for a number of diseases, like hepatitis, cholera, etc. Generally speaking, you don't want to be consuming feces.--Mr.98 (talk) 14:59, 8 January 2010 (UTC)

Water/Hydroxylic acid

Why water is also called hydroxylic acid? Is water acid? --Qoklp (talk) 06:46, 8 January 2010 (UTC)

It isn't. It's called water. Sometimes you see bullshit/joke references to water as either "dihydrogen monoxide" (it's proper systematic name, but no one ever uses this name seriously) or hydroxylic acid. If named under the standard rules of acid nonmenclature, the name "oxylic acid" or possibly "hydroxylic acid" may apply as well, but no one seriously ever uses these names. Under acid nomenclature, the acid is named based on the anion in the acid; the cation of all acids is H⁺. So, if you consider water to H⁺ and OH^- (hydroxide ion), you could kinda-sorta consider it as "hydroxylic acid". Except that nobody, ever, not even the most pedantic of chemists, would ever call it anything except water. --Jayron32 06:51, 8 January 2010 (UTC)

Besides everyone knows dihydrogen monoxide and hydroxylic acid is simply greenie scare mongering and the proper name should be Hydrogen hydroxide] Nil Einne (talk) 12:32, 8 January 2010 (UTC)

Actually, Qoklp is right. Water is amphoteric (can act as both a base and an acid), and the auto-ionization of water is a very important concept in acid-base chemistry. Hydroxylic acid is technically a correct name, as is hydrogen hydroxide. ~ Amory (u • t • c) 15:40, 8 January 2010 (UTC)

Question related to Carbon-Capture and Sequestration

Resolved

The following question occurs to me as being one that could be used as an illustration. It probably has appeared before.

What would the entire atmosphere's thickness be if all of its component molecules were liquified?

Perhaps more difficult is to ask for the thickness if the atoms were rearranged ideally in solids, but maybe someone wants to take a shot at that as well.Julzes (talk) 08:17, 8 January 2010 (UTC)

About 10 meters. Dragons flight (talk) 08:21, 8 January 2010 (UTC)

(ec) The questions are actually easy. As you probably know, atmospheric pressure at sea level is approximately equivalent to the pressure of a 10-meter layer of water. If you could liquefy the atmosphere, the entire atmosphere thickness would therefore be 10 meters if the density of the liquid is 1 g/cm3. I don't remember what the liquid air density is, but I'll look it up now. The general result is: thickness = 10 m * 1 g/cm3 / rho [g/cm3] where rho is the density of liquid or solid air. --Dr Dima (talk) 08:22, 8 January 2010 (UTC)

OK, density of liquid air at 1 atm pressure is about 0.87 g/cm3, so the thickness of the atmosphere would then be 10 m * 1/0.87 = 11.5 m . --Dr Dima (talk) 08:25, 8 January 2010 (UTC)

(Edit conflict) Well, Earth's atmosphere weighs 5x10¹⁸ kg[19]. It's mainly 78% nitrogen and 21% oxygen. Liquid oxygen has a density of 1146 kg/m^3 [20], liquid nitrogen has a density of 811.6 kg/m^3 [21] put that together and you get: ((5x10^18 kg) * 0.78)/(811.6 kg/m^3)+((5x10^18 kg) * 0.21)/(1146 kg/m^3) = 5.722x10^15 m^3 [22]. Now you have a volume, and you need to convert it to a height above the earth.

You know, wolfram alpha has all these constants, but I can't quite get it to do the math for me without copy/pasting the numbers into a new formula. Ariel. (talk) 08:35, 8 January 2010 (UTC)

I see it's a bit simple. How about the question of changing all excess (anthropogenic) Carbon to diamond. How thick would that be?Julzes (talk) 09:38, 8 January 2010 (UTC) I'll ask the question I was about to ask at the mathematics desk.Julzes (talk) 09:47, 8 January 2010 (UTC)

Distributed globally? A layer 4 microns thick per year. Concentrated in one place that's 2 cubic km per year, that would be far more diamonds than have been collected in the entire history of the human race. (Of course it takes even more energy to convert the carbon into diamond, so no one would actually want to use diamond as a storage medium.) Dragons flight (talk) 10:07, 8 January 2010 (UTC)

There is no excess carbon. It's carbon dioxide. They are not the same thing, despite media and others being lazy and calling it carbon. It's not carbon offsets, it's carbon dioxide offsets, etc. Carbon dioxide can not be turned into diamond, although carbon can be. And BTW, there is a very very small amount of it in the air - about four hundredths of a percent, and the excess carbon dioxide amounts to 8 or 9 thousandths of a percent. Ariel. (talk) 10:25, 8 January 2010 (UTC)

Essentially less than a millimeter thick for the whole history? I see the math on localising it looks correct. It helps to actually do the math. Ariel, I think I and Dragons Flight understand what you're saying.Julzes (talk) 10:35, 8 January 2010 (UTC)

And, strictly speaking, it is excess Carbon I was thinking of. Since it accumulated due to the burning of hydrocarbons, that entailed some (I know) small decline in Oxygen in not only relative but also absolute terms. Dragons flight is almost certainly correct that the ideal method of precipitating out the Carbon from the atmosphere does not entail separating the Carbon and Oxygen atoms from each other (or Carbon and Hydrogen, concerning methane) and turning the Carbon into diamond, but it's a thought if clean energy were sufficiently cheap at the point in time at which geoengineering were to take place (probably a bad thought, but this was just an abstract curiosity exercise).Julzes (talk) 11:06, 8 January 2010 (UTC)

Actually we already have very cheap and plentiful devices that can remove CO2, there is no need for geoengineering. They are called plants :) And clean energy already exists too - it's called nuclear power (especially a thorium cycle, or a cycle using nuclear reprocessing, both methods leave almost no waste behind). The only reason we use hydrocarbon fuel is that it's cheaper. Ariel. (talk) 11:22, 8 January 2010 (UTC)

You don't sound like you understand the whole situation, but I don't feel like arguing. I got the answer to the question I was asking.Julzes (talk) 11:47, 8 January 2010 (UTC)

Whether it reflects understanding of the whole situation or not, I think that summary by Ariel was pretty much nail-on-the-head. As I've mentioned numerous times, the only obstacle we face with regard to climate change is socio-economic, not technological. There's a big bubble brewing around these parts with every upstart kid trying to sell some kind of new clean technology... but we already have industrial-scale, extremely clean alternatives to hydrocarbon. They are simply undesirable for economic and social reasons. There's no requirement to develop new technologies. Nimur (talk) 15:36, 8 January 2010 (UTC)

powering a stepper motor

Hello, I've disassembled an old DVD drive and have removed the motor that rotates the disc. It has three wires. I've figured out (with the help of an elementary cell) that they need to get pulses that are each out of phase by 120° (this is but a guess). In other words, each of the three wires must be pulsed one after the other, while the other two are connected to the ground.

Is there a simple circuit I could build in order to have the motor rotate? I'd rather build a circuit from discrete elements (individual transistors) than take an IC. I presume the circuit will be similar to that of a runnning light or something like that.

On a second thought, could I also use inductors?

—Preceding unsigned comment added by 88.70.81.101 (talk) 11:21, 8 January 2010 (UTC)

A three phase system is likely a servo motor not a stepper motor. In industry, such things are generally driven with three out-of-phase alternating currents with the phase velocity determining the rate of rotation. For hobby applications it probably is possible to drive it with a sequence of pulses (which would mimic the way stepper motors generally work). Analog circuit design is not really my forte, but hopefully someone else will be along to help. Dragons flight (talk) 13:36, 8 January 2010 (UTC)

PS. This page [23] gives a somewhat clearer idea of difference than our article does. Dragons flight (talk) 13:39, 8 January 2010 (UTC)

I basically need three "outputs" out of which, at any given moment, one is at a high potential and the other two have are at a low one, and they keep alternating (like I said, running lights.) My question basically was, how to accomplish this... 92.226.94.41 (talk) —Preceding undated comment added 15:47, 8 January 2010 (UTC).

Well water smell

What are some possible causes for a house's well water smelling like rotten eggs when it comes out of just one faucet in the house? Dismas|^(talk) 13:15, 8 January 2010 (UTC)

That whatever functional molecular group emits the smell of rotten eggs has been produced by bacteria that exist in the well water. DRosenbach ^{(Talk | Contribs)} 13:21, 8 January 2010 (UTC)

Rotten eggs is usually sulfur, in this case sulfur/sulfites are reduced to hydrogen sulfide. ~ Amory (u • t • c)

If the smell is really isolated to a single faucet, you can track the plumbing back to see where that plumbing line diverges from the rest of the supply. Presumably, the source of the contamination should be somewhere along that branch. I'd use caution if this is your potable water supply, as contamination could spread, with or without the smell, to other parts of your water supply. Nimur (talk) 15:31, 8 January 2010 (UTC)

Spectrophotometer operating manual?

Does anyone know where I can find an operating manual for a Varian AA-1275 atomic absorption spectrophotometer? I've already tried the manufacturer. The book's called “Atomic Absorption Spectrophotometers AA-1275 & AA-1475 Installation Instructions & Operation Manual”, but amazon doesn't have it. Nikkimaria (talk) 14:28, 8 January 2010 (UTC)

Books about the creation of new breeds

Hi all, I would like to know if you could suggest me a book about the creation of new breeds; specific texts about breeding of dogs and fishes, and about interspecific hybridization procedures in general, are welcome, althought not strictly required. Thanks. --87.3.120.61 (talk) 14:48, 8 January 2010 (UTC)