Wikipedia:Reference desk/Archives/Science/2012 February 11

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February 11

Average lifespan of the stars

What is an average lifespan for the stars in the universe. I also want to know the relationship between mass and lifespan. According to this , our sun has 1 solar mass and its lifespan is about 10 billion. So if a star has 2 solar mass and so on or has less than .9 solar mass and so on. What are their expectancy lifespan?Pendragon5 (talk) 01:37, 11 February 2012 (UTC)

Never mind, i think i have found an awesome data table of it.Pendragon5 (talk) 01:52, 11 February 2012 (UTC)

Note that you would get a very different answer if you averaged by number of stars or by mass of stars. StuRat (talk) 01:57, 11 February 2012 (UTC)

Valence of argon in argon fluorohydride

What is the valence of argon in HArF (argon fluorohydride)? Until recently Wikipedia stated the maximum valence of argon to be 0, but R8R Gtrs tells me that it should be +2. Double sharp (talk) 02:07, 11 February 2012 (UTC)

• Well, if argon is indeed forming covalent bonds with both H and F, then the valence of Ar there is, by definition, 2 (note that this is not the name as having a +2 charge). Considering this molecule breaks apart at temperatures above -256°C, I think it's still safe to consider Argon to have max valence 0 for any practical purpose. LukeSurl ^{t c} 13:11, 11 February 2012 (UTC)

Why do we find baby animals cute?

Has there ever been an attempt to explain why humans find baby animals cute, particularly babies of other mammals? HiLo48 (talk) 02:51, 11 February 2012 (UTC)

I'm guessing there'll be some info at neoteny, though I don't know how much or how specific to your question. --Trovatore (talk) 02:52, 11 February 2012 (UTC)

The evolutionary adaptation is that we think our babies are cute so we will take care of them. By transference, the baby-like features of other animals (whether juvenile or adult) trigger the same response. StuRat (talk) 03:30, 11 February 2012 (UTC)

Yeah, I get the idea that it's good for humanity to find its own babies cute. But why the other animals? Personally, I reckon some human babies are pretty ugly, but every puppy is cute. As an Australian, I think about our native marsupial babies. Cute as all heck (I really must upload my baby wombat pics), but humans evolved on completely different continents. Why should we care? HiLo48 (talk) 03:38, 11 February 2012 (UTC)

I just noticed that wombat sounds a lot like womp rat. Coincidence? --Trovatore (talk) 03:43, 11 February 2012 (UTC)

Probably just a coincidence. But thank you for causing me to become educated about womp rats. HiLo48 (talk) 04:17, 11 February 2012 (UTC)

A baby kangaroo is not cute. Mitch Ames (talk) 11:26, 11 February 2012 (UTC)

I totally agree. The marsupial stage kangaroo is kinda nasty. When they're hopping around though, they get cuter. Shadowjams (talk) 18:00, 12 February 2012 (UTC)

Like HiLo is getting at, you'd think we evolved to find cuteness in human baby traits, but in reality, the traits we evolved to find cute are very general. An inability to move easily on one's own, small size, big round eyes, certain noises. And there would have been little need to evolve more specificity on that. It's not like a tiger mother would have let you waltz up and take her pups. Heck, maybe we find baby animals cute just to keep us from attacking them and incurring their mothers' wrath. Someguy1221 (talk) 04:23, 11 February 2012 (UTC)

I'm suspicious that common pets have undergone some degree of adaptation as brood parasites. Wnt (talk) 07:52, 11 February 2012 (UTC)

Maybe it's to try and prevent us from destroying the next generation's breeding stock, and ensure sustainability? --TammyMoet (talk) 09:20, 11 February 2012 (UTC)

There's likely several things going on. First off, the "find babies cute so you take care of them" is something that would be evolutionarily necessary for more animals than just humans. In general, it's something all mammals would need (with their reproductive strategy of investing a large amount of effort into a few offspring), so it makes sense that the "find babies cute" would have evolved early and be shared by all mammals. (Most of the "cute baby animals" are mammals - baby flies, baby bees and even most baby birds are ugly as sin, at least from a human perspective. Mitch's baby kangaroo doesn't count because the adults don't see it at that stage. Human embryos in the womb aren't all that cute either.) So the answer to the question "why are most baby mammals cute?" may be much the same as "why do most mammals have hair?" - an early mammal evolved to have cute babies, and the cuteness stuck around because it was useful for many species. The other thing to remember is that it's not so much that babies evolved to be cute, but that "cute" evolved to fit what babies looked like. The large-in-relationship-to-head eyes, the rounded features, etc. are really traits that the babies would have regardless (and are shared by more than just human babies). The innate response to those distinguishing features is primarily there in humans to get us to protect and care for human babies, but there isn't enough harm in finding baby pigs (or baby tigers) cute that humans would evolve to refine our "cuteness" detection to distinguish a big-eyed snub-nosed pig from a big-eyed snub-nosed human. -- 67.40.215.173 (talk) 00:24, 12 February 2012 (UTC)

I found some books and articles ([1]) that discuss how neoteny is accelerated in domestic animals like pets for the reason Wnt says above. But that dosen't completely explain why wild animals would be seen that way. Truthfully it's probably not so much that big foreheads, eyes, and ears are cute so much as those features signify infancy across most mammals and infancy is cute to all of us for obvious evolutionary reasons. Shadowjams (talk) 18:00, 12 February 2012 (UTC)

Another possibility is that we are attracted to young animals since they aren't generally dangerous, and are more trainable, so we have a chance of adopting them and forming a symbiotic relationship. While trying to adopt an adult wolf would have been rather dangerous, attempting to adopt a wolf pup was more likely to succeed (and if it didn't, you'd just kill it and eat it when it got too big). This was no doubt important to human survival, not just for dogs, cats, and horses, but also herd animals, chickens, birds used for hunting, etc. StuRat (talk) 18:45, 12 February 2012 (UTC)

FWIW, precocial baby birds are often very cute indeed. Chicken chicks, ducklings, cygnets, even baby gulls (for those that have seen them). Big-eyed, plaintively-cheeping little balls of fluff. Does texture play a part in cuteness too, do you reckon? --Kurt Shaped Box (talk) 23:27, 12 February 2012 (UTC)

Magnetic liquid

Are there any magnetic liquids? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 03:27, 11 February 2012 (UTC)

There certainly are liquids which would be attracted by a magnet (just mix some oil with iron filings). But a liquid that acts as a magnet sounds difficult to achieve, because the north poles and south poles would bind to each other and cancel each other out. At best, I'd expect one that acts like a magnet when exposed to a magnetic or electric field or charge. StuRat (talk) 03:33, 11 February 2012 (UTC)

We have articles on Ferrofluid and Magnetic ionic liquid. -- 182.232.144.48 (talk) 03:57, 11 February 2012 (UTC)

Stefan–Boltzmann law

I was able to do question i asked above due to the ratio between the stars but i don't know how it actually works. Is the energy the star radiate the same as luminosity?Let use our sun as an example. :$j^{\star }=\sigma T^{4}.$ Ok the sun Temperature is 5778K so according to the formula i do 5778^4 X $\sigma$ (which is about $5.670400\times 10^{-8}$ right?) = $j^{\star }$

$P=Aj^{\star }=A\varepsilon \sigma T^{4}.$ Then according to this formula i take the $j^{\star }$ X A (the surface area of the sun). So what number A so that i can put it in my calculator? What unit is A? Like is it in km^2 or m^2 or... The answer suppose to be ~98 lm/W efficacy, that's the luminosity of the Sun. And what is 98 lm/W even mean? I understand apparent magnitude and absolute magnitude but i don't understand this luminosity.

And some other questions i want to be clear. Is the energy the star radiates the same as luminosity? This luminosity is different from apparent magnitude and absolute magnitude.Pendragon5 (talk) 05:24, 11 February 2012 (UTC)

And i want to ask about the units of the constant too: $\mathrm {J\,s^{-1}m^{-2}K^{-4}}$. Is $K^{-4}$ supposes to mean that when i use something that has a unit K then the constant = $5.670400\times 10^{-12}$ instead $5.670400\times 10^{-8}$ right?Pendragon5 (talk) 22:42, 11 February 2012 (UTC)

No, it has nothing to do with that. It means that part of the units of the constant is kelvins-to-the-minus-fourth-power. So when you multiply it by T⁴, which has units of kelvins-to-the-fourth-power, that part of the units cancels out. There may be some information at dimensional analysis, although I haven't read that article (at least recently) so I can't guarantee it. --Trovatore (talk) 09:02, 12 February 2012 (UTC)

Some isotopes of superheavy elements

Has ²⁶⁹Sg been confirmed? What about ²⁶⁶Rf and ²⁶⁸Rf? What values should we use for the atomic weights for rutherfordium ([266] or [267]) and seaborgium ([269] or [271])? Double sharp (talk) 05:57, 11 February 2012 (UTC)

Effect of exercise on metabolism

Must... change... metabolism!

Take a hypothetical individual with a white collar job who is largely immobile, and consequently out of shape. This individual begins to exercise, and burns 300-400 calories per day. However, for each calorie burned, s/he makes up for it by eating exactly as many calories (plus a few extra to balance for digestion).

Which of the following is more likely to be true?

• The individual now has an increased metabolism (the body burns more calories to allow the individual to be ready to exercise at any moment's notice). As such, this person will lose weight in the longrun.
• The individual now has a decreased metabolism (the body has become more efficient at burning calories). As such, this person will gain weight in the longrun.

Magog the Ogre (talk) 08:12, 11 February 2012 (UTC)

Have you read Excess post-exercise oxygen consumption? Exercise will lead to an increase in muscle mass and brown adipose tissue, which both have a higher fuel requirement than white adipose tissue, therefore the increase in basal metabolic rate that occurs after exercise will need to be fuelled by lipolysis. The net effect will probably be weight loss unless you gain sufficient muscle mass to compensate. --Mark PEA (talk) 13:55, 11 February 2012 (UTC)

But, of course, there's no reason to think that this is exempt from the effect of resulting in more hunger, and thus more calories consumed, just like those calories burnt during exercise. StuRat (talk) 18:37, 11 February 2012 (UTC)

Exercise will result in an increase in muscle mass, and increased muscle mass results in increased basal metabolic rate. So yes, the individual will be losing _fat_ in the long run. S/he will probably be gaining muscle faster than he is losing fat under these conditions. Both fat loss and muscle gain will most likely be minuscule (although this depends on the type of exercise.)

However, the assumption that "s/he makes up for it by eating exactly as many calories" is most likely unwarranted - unless the person is under strict supervision, eating pre-portioned and pre-measured meals, and never leaving food on the plate. If you want to ask a more realistic question, ask what happens when that person starts exercising without changing dietary habits (but also without strict enforcement of zero net caloric balance.) In that situation, this individual's appetite most likely will not compensate completely for extra calories burned while exercising. The individual will lose fat, gain muscle, and lose some weight (though not nearly as much as he'd lose if he were to undertake a caloric restriction in addition to exercise.)

According to this 1997 meta-analysis, overweight adults on aerobic exercise programs without caloric restriction end up losing 0.5 lb of fat per week and gaining 0.05 lb of muscle per week, on average. --Itinerant1 (talk) 07:35, 12 February 2012 (UTC)

Many studies go further, and say that not only this individual's appetite will not completely compensate for extra calories burned, but that in sufficiently overweight individuals (but not in lean individuals), the degree of compensation is essentially zero: aerobic exercise does not result in more hunger or in increased caloric intake. [2][3][4][5] --Itinerant1 (talk) 08:26, 12 February 2012 (UTC)

Continued on February_13
--Seren-dipper (talk) 20:38, 16 February 2012 (UTC)

Owl faces

Squint. It's a Grey alien. --Kurt Shaped Box (talk) 05:58, 12 February 2012 (UTC)

On a slightly related note to (and inspired by) the baby animals thread above...

Has anyone else here heard the theory that humans tend to have very strong visceral reactions to owls (especially unexpected owls), either positive or negative, because the facial proportions of an owl tend to be very close to the facial proportions of a human? Any thoughts on whether this is valid or not? --Kurt Shaped Box (talk) 13:07, 11 February 2012 (UTC)

I have heard it somewhere, but only in a romantic/fantasy novel. In a more practical sense, some owls are quite big - 600 mm or more tall. That's big enough to do some very serious damage if it attacks you, so a fright response to suddenly noticing such an owl close up would be appropriate. Keit143.238.215.185 (talk) 16:11, 11 February 2012 (UTC)

I think we have strong visceral reactions to them because they have huge eyes that are fixed in their faces. Eye contact is a very strong emotional cue. Looie496 (talk) 19:26, 11 February 2012 (UTC)

There's something about their eyes, for certain. When watching videos on YouTube, I can go from thinking that a certain owl is cute, to feeling unnerved on some odd, very deep level, just by seeing it narrow its eyes, or close one eye while leaving the other open, or do a feather trick to change the apparent shape of the head while keeping the eyes fixed. Some sort of uncanny valley thing? --Kurt Shaped Box (talk) 22:02, 11 February 2012 (UTC)

There's a lot of lore connecting owls with alleged extraterrestrial aliens - see Communion (book) and [6]. -- Jack of Oz ^{[your turn]} 03:32, 12 February 2012 (UTC)

I can believe that. Once I was driving down Mount Baw Baw in lightly falling snow when I encountered five Tawny frogmouths sitting on top of five consecutive white roadside posts. With their spread out lower feathers there was a continuity of line from the tops of their heads to the ground. Very alien. Very spooky. (Mentioned that location especially for the Aussies here) HiLo48 (talk) 04:18, 12 February 2012 (UTC)

Not just owls, but predators in general tend to look attractive, perhaps because facially they "look like us", i.e. they have binocular vision. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:06, 12 February 2012 (UTC)

Hysteresis loss in ferrittes

Is it true that the hysteresis loss in a heavily saturated ferrite core will be much less than in its unsaturated state? Will the loss essentially approach zero?--92.28.73.60 (talk) 14:43, 11 February 2012 (UTC)

No - sort of. As coil current is increased from zero, a greater range of magenetisation is tranversed (the area within the B-H loop is increased), therefore the power dissipation increases. If coil current is increased so as to go beyond saturation, the area within the loop cannot increase, and the power dissipated cannot increase beyond a maximum value. The dissipation cannot go to zero as the area within the loop does not decrease. However there is theoretically a complicating factor. The dissipation will increase the temperature of the core. If the curie temperature is approached, the saturation flux density will decrease (essentially, at the currie temperature, typically around 200 C for a ferrite, magnetic materials loose their magnetic properties). This will reduce, but definitely not bring to zero, the hystereis loss in a sort of temperature-saturation feedback loop. You may have been thinking of the Q-factor. The Q-factor of an inductor can increase at currents beyond saturation, as the fraction of back-emf voltage due to the core (with pegged core loss) becomes lower compared to the back-emf due to the intrinsic inductance (the inductance the coil would have with no core at all). A competent designer would never operate a core that way however. To approach the curie temperature in typical cores, you would need very odd operating conditions, such as an ambient temperature likely to give lots of problems. Keit143.238.215.185 (talk) 15:53, 11 February 2012 (UTC)

I should clarify. I meant the loss round a minor loop (due to a small superimposed signal) cf the biasing in the saturation zone. my thinking is that the loss that the small signal experiences should be small.--92.28.73.60 (talk) 16:22, 11 February 2012 (UTC)

Yes - that would be correct. If the core has a very "square" B-H characteristic, the drop in dissipation when the bias current is on would be dramatic, and dissipation could easily be driven to near zero. Keit143.238.215.185 (talk) 16:39, 11 February 2012 (UTC)

Testing medicine by ignorant tested person

To avoid any placebo effect, could a medicine be tested without the knowledge of the tested person? Just imagine that you mix up Prozac in someone's food. Does this, ignoring all legal and moral implication, make sense? Ib30 (talk) 16:55, 11 February 2012 (UTC)

See informed consent. --Tango (talk) 16:58, 11 February 2012 (UTC)

As Tango has said there's little chance that such experiments would get ethical approval. In other words, it doesn't make sense to ignore all legal and moral implications. In any case, it's not clear why it's so important to 'avoid any placebo effect'. A properly designed randomised, placebo controlled, double blind trial is pretty much the gold standard for clinical trials and is generally held to work well. The fact you have a placebo effect isn't considered a show stopper if you account for it. In fact, if your drug has an effect but it's barely as strong as the placebo effect (so potentially could be missed in such a trial), it's unlikely to be considered useful. So there's little point avoiding the placebo effect. (Note a trial without a control group is usually a poor trial. In other words even in this 'secret testing' scenario, you still need a group you aren't giving the drug to, if you didn't realise that you may want to read a bit more about how reserch is conducted.) Also some medicines are not tested against placebos but against existing medicines which you're hoping to beat, or at least match (if the other one is also still patented so you feel you can make money by providing an equally effective competitior). Not to mention if it's secret testing, this is going to make obtaining feedback from the patient difficult. P.S. A number of the links may be useful. They discuss some of the issues with the way clinical trials are conducted. Just as a note I'm not trying to suggest that current practice is definitely perfect, simply that I don't believe you will find many people wishing 'if only we could give our drug secretly to avoid the placebo effect'. Nil Einne (talk) 17:09, 11 February 2012 (UTC)

(Also, merely matching effectiveness might be far from useless with say fewer, milder and/or different side effects, widening a narrow toxic:effective dose ratio, or if enough people are alleric to the first drug) Sagittarian Milky Way (talk) 19:56, 11 February 2012 (UTC)

Note that testing by pharmaceutical companies without informed consent is allegedly quite rampant in Africa. There is very little that can be done at the judicial level about this, on account of the limited scope of most US criminal laws with respects to things that happen extraterritorially, and the secrecy that prevails over such tests. It's not a pretty situation. --Mr.98 (talk) 18:25, 11 February 2012 (UTC)

We actually have a Medical experimentation in Africa although it isn't a great article and seems to be primarily concentrated on historic stuff (perhaps because that's the best documented). I do believe even if companies wanted to, carrying out that sort of stuff even in Africa isn't that likely. It's one thing to give illiterate people information in a language they don't even understand or give children or patients drugs without properly explaining to them or their parents that they are untested and unapproved or misleading about the availability of other drugs; it's another to give them drugs completely secretly since in that case it's fairly difficult to even pretend you have informed consent without outright lying. (I don't think Mr.98 intended to suggest this is likely, I just felt it worth pointing out for the benefit of the OP.) This is not to underestimate the highly dubious practices some companies have shown. While not relating to drug trials, Contaminated haemophilia blood products seems to be another example which I found in this [7] likely somewhat biased source and [8] also has some discussion. Nil Einne (talk) 21:40, 11 February 2012 (UTC)

I've heard various, conflicting reports on it. There are some pretty shady practices going on at the moment. I'm not sure the full extent is known. I'm not sure there's any line between not telling people at all and telling them lies and/or things in a language or jargon they don't understand. --Mr.98 (talk) 01:19, 12 February 2012 (UTC)

So, sometimes lack of moral considerations is good for science? Ib30 (talk) 21:22, 11 February 2012 (UTC)

As well as the problems Nil Einne mentions, drugs trials require very carefully controlled doses. Mashing Prozac into food carries the risk that a) they won't finish their meal (and thus will underdose) or b) they'll take seconds (and will overdose). You'd also run into the problem that if it turns out the drug has an unexpected dangerous side-effect, the people involved in the trial aren't going to report it (which would instantly stop the trial). There's similarly a risk that people will take another drug with it - for instance, painkillers or alcohol or, in the worst case, other prescription drugs. This will a) invalidate the results you get (since you can't separate the effects of the different drugs, and some drugs can cancel each other out or react in unexpected ways) and b) potentially kill the patient. Overall, it wouldn't be recommended. Smurrayinchester 20:03, 11 February 2012 (UTC)

The phrase "good for science" in this loaded question is too vague for a "yes" or "no" answer. Unit 731 in Japan performed all sorts of butchery on prisoners of war without regard for moral considerations, leading (according to our article) to a couple of biological weapons. Was this "good for science"? There was some advance in knowledge, but deciding whether this was "good for science" means you have to weigh this against the costs. Comet Tuttle (talk) 00:35, 12 February 2012 (UTC)

Was the Tuskegee syphilis experiment good for science? Maybe it advanced knowledge of syphilis a tiny bit, but it did so at the cost of human lives and scientific trust. In the long run, such things are not good for science. Scientists are clever — they shouldn't have to resort to unethical practices to learn things. To do so is to be not much better than the Nazis doctors who experimented on their prisoners. That sort of thing hurts science as an institution in the long run in a way that is more profound than the short term gains in terms of data. --Mr.98 (talk) 01:19, 12 February 2012 (UTC)

Nazi human experimentation#Modern ethical issues, though rather short, mentions some interesting issues. It could certainly be expanded, possibly into a page of its own. -- ToE 03:42, 12 February 2012 (UTC)

I can't help but feel that we're part of either a psychological study or possibly a student's essay assignment that hasn't been fully explained to us, but no matter. The phrase "good for science" is, as Comet Tuttle notes, vague to the point of uselessness; it depends far too much on how one chooses to define "good" and "science". One can get into very murky waters very quickly. Consider the testing of a new AIDS/HIV vaccine. What's the 'best' way to determine whether or not it works in humans?

The fastest way to get the answer is to administer the vaccine to a trial group of twenty people, expose those twenty people to live HIV, and then check back in six months or a year to see which ones have a measurable load of HIV in their blood.

How is the vaccine testing actually done? You give your trial vaccine to hundreds or thousands of individuals (generally individuals in higher-risk communities, whom you expect will be exposed to HIV: sex workers, people in countries where there are high overall infection rates, individuals with limited access to barrier products like condoms, etc.); you'll probably also have to give a placebo to the same number of individuals, as the idea of being potentially vaccinated may affect the study participants' behavior and you'll need to control for that. You then wait several years and count the number of HIV-infected individuals in the control group versus the vaccinated group; if there's a statistically-significant difference then your vaccine probably works. Dozens or hundreds of study participants are infected with HIV during the course of the trial, and millions worldwide are infected while waiting for a vaccine.

The first method gives a clearer answer, works faster, and exposes a much smaller number of people to the risk of infection—but would never be permitted. Your assignment is to read the articles on utilitarianism, medical ethics, and devil's advocate, and report back in the morning. TenOfAllTrades(talk) 17:27, 12 February 2012 (UTC)

I don't think anything can be "good for science" or "bad for science" in that way. Science is a method. It isn't a goal. The goal of medicine is to allow people to live longer lives with less suffering. Would human experimentation with informed consent help achieve that goal? Plenty of scientists have asked that question (and not just the war criminals - legitimate, law abiding researchers debate this issue all the time, this is the first paper Google found me on the subject, but there are many others). --Tango (talk) 17:42, 12 February 2012 (UTC)

I think it would be plausible to look for "natural experiments" in this regard. Mix-ups with prescription drugs filled at pharmacies are remarkably common, and people therefore receive the drug in the way the OP suggests. Of course, if the condition it is being tested on is rare, there may not be any usable data, but for some common conditions it is conceivable you could learn something. Wnt (talk) 09:56, 13 February 2012 (UTC)

Brain transplant

Is it at any level possible? a way to transfer one's consciousness (whatever that is supposed to mean) to another body? it can have many good results, such as a cure for sexual identity disorder and stuff like that so... is it possible? Are people even working on it?--Irrational number (talk) 19:07, 11 February 2012 (UTC)

It's a long way off. Also, since your brain is the essential "you", I'd call it a body transplant. StuRat (talk) 19:20, 11 February 2012 (UTC)

No, it's not currently possible. Currently the state of the art is that the brains of a few animals such as frogs can be removed from the body and kept alive for a short while, but they can't be inserted into a new body: the tissue would be rejected, and the spinal cord and other nerves won't make functional connections with the nerves in the body. There is going to have to be a lot of progress before anything like this becomes feasible -- curing spinal paralysis should be very easy in comparison. Looie496 (talk) 19:23, 11 February 2012 (UTC)

I know it's not currently possible, I meant theoretically.--Irrational number (talk) 19:42, 11 February 2012 (UTC)

Head transplant is as close as anyone's gotten. Someguy1221 (talk) 20:21, 11 February 2012 (UTC)

So, from that article, it looks like head transplants are possible, but not reconnecting the nerves. Thus, the brain is kept alive by the blood supplied by the new body, and would have senses of sight, smell, taste, hearing, and touch (on the head only), but they would be a quadriplegic. Presumably the brain stem from the original animal is retained, to control heart beats and breathing. Another option is to retain the original head, in which case the new head is simply "parasitic".

As far as reconnecting nerves goes, there the problem is it's difficult to connect the thousands of nerves all correctly. One option I've heard of with severed nerves in the same body is to connect both sides to a microchip, which can be used to switch the connections quickly, without additional surgery. Then, there's a long process where you tell the patient to "wiggle their thumb" and keep trying different connections until the thumb wiggles, then repeat for every other sensation or response. With the head transplant, though, you might not have a 1-to-1 correspondence between nerves. That is, some people may have more nerves than others. StuRat (talk) 20:01, 12 February 2012 (UTC)

We have an article, brain transplant. The links at the bottom include the related mind uploading article. Comet Tuttle (talk) 21:50, 11 February 2012 (UTC)

Race, gender, testing, intelligence, ability, and predisposition by distraction

I recently listened to http://www.radiolab.org/blogs/radiolab-blog/2009/jan/27/the-obama-effect-perhaps/ which seems to explain quite a bit about several age-old controversies. Does anyone know where to find the peer reviewed research described at 6:30-7:45 and 8:30-8:45 in the recording? Thank you. 85.230.127.113 (talk) 21:47, 11 February 2012 (UTC)

Absolute temperature ?

What is the absolute temperature of the sun? I know its effective temperature is 5778K. In the sun article: it says: "Temperature Center (modeled): ~1.57×107 K"----> is this the absolute temperature of the sun? Or is the Corona: ~5×106 K temperature is the absolute temperature?Pendragon5 (talk) 22:39, 11 February 2012 (UTC)

The suns temperature varies depending on the rasdil distance from its center. I believe its cooler inside.--92.28.73.60 (talk) 22:48, 11 February 2012 (UTC)

Nah it's hotter inside. The deeper you go inside the hotter. I know the sun's temperature varies depend on where in the sun but there is a certain number that stands for absolute temperature. When people talk about absolute temperature of the sun, what is it?Pendragon5 (talk) 23:03, 11 February 2012 (UTC)

The term absolute temperature just means temperature measured on a scale whose zero is absolute zero, for example the Kelvin scale. At the temperatures we're talking about here, it doesn't make a whole lot of difference whether you report the temperature in kelvins or in degrees Celsius. According to our solar core article, the temperature at the center is around 15 million kelvins. --Trovatore (talk) 23:17, 11 February 2012 (UTC)

(On the side issue: The solar corona is indeed hotter than the (somewhat ill-defined) "surface of the Sun". Our article says that the corona is on the order of a million degrees. However this is somewhat misleading because the corona is a very thin gas; your spaceship is safer in the corona than it is at the solar surface.) --Trovatore (talk) 23:25, 11 February 2012 (UTC)

In the Stefan–Boltzmann law article, they says T = absolute temperature. What absolute temperature they are talking about? Let use the sun as an example, there are 3 kinds of temperature: the surface's temperature, the core's temperature and the corona's temperature, so which is the one they are using in the formula?Pendragon5 (talk) 23:38, 11 February 2012 (UTC)

In that context, T is the absolute temperature of the radiating object, whatever it happens to be. For the case of the Sun, you want to use the temperature at the "surface of the Sun" (a slightly ill-defined notion as I mentioned). Of course, the other parts of the Sun are also radiating, but the parts below the surface radiate light that gets quickly re-absorbed (so we never see it), and the parts above the surface are too thin to contribute much. --Trovatore (talk) 23:57, 11 February 2012 (UTC)

You may find the article photosphere useful. It discusses what effective temperature really means in this context and how it relates to the actual temperature of the star at various depths. (Note, T is the Stefan-Boltzmann law is the effective temperature - when it says "absolute" it just means it is measured relative to absolute zero, it doesn't mean that it's the actual temperature of the star.) --Tango (talk) 17:49, 12 February 2012 (UTC)

light speed limit

Im no expert but when you say that you'll go back in time if you travel faster than light the same thing as saying that only superman can run for 500mph. MahAdik _usap 23:18, 11 February 2012 (UTC)

I sort of see what you're saying. The way I heard it explained is that we are travelling through time at the speed of light. If you travel in our three dimensions, you are either adding to or taking away from the speed we travel in time. So if you can go faster than the speed of light, then time is travelable. Does this help? --T H F S W (T · C · E) 23:35, 11 February 2012 (UTC)

(edit conflict) I'm having trouble finding the question here. But if you're asking if it is impossible to travel faster than light, and thus not possible to go back in time, then yes, more or less that's the case. If you could travel faster than light, there would be reference frames in which you could be perceived as traveling back in time. It's a complicated thing. See Tachyonic antitelephone for something of an explanation, though I don't know if it will be comprehensible unless you've got a little more science under your belt... --Mr.98 (talk) 23:38, 11 February 2012 (UTC)

If this helps, the reason that you can't travel as fast as light is that it would take an infinite amount of energy to get you up to that speed, as discussed at our article section Speed of light#Upper limit on speeds. Comet Tuttle (talk) 00:17, 12 February 2012 (UTC)

I asked because i think that all the fuzz about the possibilty of time travel is just a misunderstanding about the light speed limit, But of course i can be totally wrong. MahAdik _usap 00:20, 12 February 2012 (UTC)

You will probably enjoy our article Time travel. Comet Tuttle (talk) 00:24, 12 February 2012 (UTC)

I really liked the answer given by T H F S W. Its just the same as I believe (and of course its true). I think its called the Minowski invariant or something.--92.28.73.60 (talk) 01:19, 12 February 2012 (UTC)

Except that you cant add to the speed we travel through time: you can only subtract from it. :-( — Preceding unsigned comment added by 92.28.73.60 (talk) 01:35, 12 February 2012 (UTC)

One of my college math teachers said, "If you start with incorrect assumptions, you're liable to get interesting results." There is no known way to go backwards in time. But if you could, the results could be interesting. Hence it's a frequent sci-fi topic. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:03, 12 February 2012 (UTC)