Wikipedia:Reference desk/Archives/Science/2011 November 30

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November 30

Vanda Station and Hope Bay

Is these two places climate of Antarctica tundra or ice cap.it said these two place highest track temperatures is 15 C/59F. I am confused if the these places climate is ice cap or tundra. I never hear ice cap climates (EF) get temperatures 40F or higher. If I learn it happens that is weird.--69.228.24.198 (talk) 00:09, 30 November 2011 (UTC)

Neither -- that place is properly classified as a rocky desert. 67.169.177.176 (talk) 06:34, 30 November 2011 (UTC)

Vanda Station is actually in a rocky area, not tundra or ice cap.

Hope Bay is coastal, so it's not entirely surprising that they occasionally get warm breeze off the ocean. APL (talk) 08:49, 30 November 2011 (UTC)

Low-elevation nunataks may occasionally absorb enough sunlight to heat up. ~AH1 ^(discuss!) 01:37, 1 December 2011 (UTC)

Carbon cycle

through what process does the carbon move from plants to animals, and animals back into the air? — Preceding unsigned comment added by Denny636 (talk • contribs) 00:41, 30 November 2011 (UTC)

Through the carbon cycle. Plasmic Physics (talk) 01:31, 30 November 2011 (UTC)

First step is herbivory. Graeme Bartlett (talk) 09:01, 30 November 2011 (UTC)

The carbon cycle doesn't really explain it. After herbivory comes digestion and then cellular respiration. SmartSE (talk) 13:19, 30 November 2011 (UTC)

What are you saying, that the carbon cycle is a scientifically false concept? It explains exactly how carbon moves. Plasmic Physics (talk) 01:28, 1 December 2011 (UTC)

Consider agricultural emissions: belching of animals, removal of carbon sinks and eutrophication. ~AH1 ^(discuss!) 01:34, 1 December 2011 (UTC)

What's this SPAAV?

http://img.photobucket.com/albums/v43/Luigi/Choplifter%203/SPAAV.png

• 4 Autocannons
• 7 Roadwheels

--Arima (talk) 04:37, 30 November 2011 (UTC)

Super Pixelated Amphibious Assault Vehicle? -- 203.82.66.204 (talk) 05:49, 30 November 2011 (UTC)

Self-propelled anti-aircraft vehicle, I think.--Itinerant1 (talk) 06:02, 30 November 2011 (UTC)

Neocortex and suffering

I've been a vegetarian for a bit over a year, with the understanding that the animals we tend to eat, like cows (but probably not fish), can 'experience' suffering. But the other day, my friend made the claim that a well-developed neocortex was necessary to experience suffering, and that only humans have a sufficiently advanced neocortex for this. His claim seems spurious, but I don't know enough to refute him. What does the reference desk think? 74.15.136.30 (talk) 07:19, 30 November 2011 (UTC)

See Pain in Animals and Animal psychopathology.-- Obsidi♠n Soul 07:26, 30 November 2011 (UTC)

As an aside, at least animals can run away or fight back. Eating plants, which are tied to the ground and thus lack the ability for either flight or self-defense, now that IS immoral. We should be protecting those life forms which are most vulnerable! --Jayron32 07:29, 30 November 2011 (UTC)

Don't underestimate Plant defense against herbivory. :P -- Obsidi♠n Soul 07:38, 30 November 2011 (UTC)

That statement would appear self-evidently false to anyone who ever had a pet. Just imagine, say, pricking a cat with a sharp needle. Pain in animals says: "All vertebrates and some invertebrates are capable of nociception, a neural response to intense or damaging stimuli. Nociception can be observed using modern imaging techniques, and a physiological and behavioral response to nociception can be detected but, presently, there is no objective measure of suffering."--Itinerant1 (talk) 07:30, 30 November 2011 (UTC)

Yep, avoidance learning. Furthermore, the neocortex is the sensory and cognitive seat of mammals (certainly not humans alone), but that doesn't preclude similar functions of other parts of the brain in other animals which lack it.-- Obsidi♠n Soul 07:38, 30 November 2011 (UTC)

It's at least partially a philosophical question that hinges on how your define "suffering". Is it "suffering" if the animal is in an unpleasant or painful situation, but isn't capable of understanding that things could be better? Couldn't all of us be in an unpleasant or painful situation, compared to other possible situations that we're not even aware of? Is suffering relative? Or is there some objective level of unpleasantness and pain beyond which "Just life" becomes "Suffering"?

Better to restrict yourself to answerable questions like "Do animals react to pain?" and "Are livestock subjected to pain?" APL (talk) 08:44, 30 November 2011 (UTC)

Life is pain. Anyone who says differently is selling something. --Jayron32 13:39, 30 November 2011 (UTC)

(e/c)See also pain in fish. Also note that suffering includes more than physical pain.--Shantavira|^{feed me} 08:48, 30 November 2011 (UTC)

Okay, here's a question that confuses me: what would be the difference between a robot that was programmed to avoid certain stimuli, and an animal that suffers in response to the same stimuli? 74.15.136.30 (talk) 15:49, 30 November 2011 (UTC)

In my view, we attribute pain on the basis of expressive behaviors, such as wincing, squealing, trying to escape, having an unhappy facial expression, or verbally complaining. This view is not widely accepted, but I don't see any other explanation that works. Talking about robots raises difficulties because many people have strong prejudices, but I think it is more useful to ask whether pain would occur in an alien lifeform that has a humanlike shape, an ability to talk, and responds to bodily damage in the same way that humans do, but has a different sort of nervous system. Looie496 (talk) 18:25, 30 November 2011 (UTC)

Since it's a quale, you could also ask how we're sure pain occurs in humans.  Card Zero  (talk) 22:17, 30 November 2011 (UTC)

Without getting into the status of either issue, I think that there's a distinction to be made here between whether a "well developed neocortex" is required and whether a human neocortex is required. My vague recollection (very possibly wrong - I should look further) is that dissociative anaesthetics like ketamine interfere with transmission of stimuli from the thalamus to the neocortex (see [1], which I really ought to read). Now the thalamus is the seat of "consciousness", but apparently pain may be another situation. A person having a tooth pulled out under the influence of such a drug might be aware that it's being yanked, yet not report being in pain over it. Of course, just because a person doesn't remember or consciously speak of pain doesn't necessarily prove that there isn't some other part of the brain that is suffering terribly ... if you're going to worry about animal rights, might as well worry about the rights of your limbic system? Now in any case, as ketamine and other dissociatives are as effective (?) in cute furry animals as in people, this argues that their neocortices are up to the task, whatever that task is.

Really, the argument that animals don't feel pain is probably more a political sophistry than a real issue. I don't believe anyone watching dog-fighting or bear baiting is really cheering along while imagining that the animals are mere automatons miming the impression of pain. The meaningful issues are whether pain is "truly" felt by animals - whether they "truly" think and experience as we do - and whether human moral codes should extend to such situations. After all, cats play with mice, dogs tear prey limb from limb, and animals don't show much concern for animal rights that I can discern. Nature photographers are never called to account for allowing the lions to devour the elephant. Why should a human who puts, say, two dogs in a position to tear one another apart then be blamed for the immorality that the dogs commit? But such issues stray from beyond the purview of the Science desk. Wnt (talk) 18:42, 30 November 2011 (UTC)

All the brain does is to execute an algorithm that processes information. Therefore what matters is if some specific algorithm is running. E.g. people who experience phantom pain do so because the brain's internal model about the body still assumes that the amputated limb is still there. The brain uses certain algorithms to compute the state of the limb, but without visual input, this starts to drift (similar to how a plane's position determined by inertial navigation will slowly drift away relative to the true position). Then by using a mirror, the brain can be tricked into thinking that the remaining limb is the amputated limb. The brain then takes this as input for its internal model, the state of the amputated limb is now modeled as being in a less awkward state and the phantom pain is gone.

The very definition of a person's identity is also encoded in the algorithm the brain effectively runs. This means that to let someone experience pain, all you need to do is to run the right algorithm on some machine. The mere act of running that algorithm gives rise to the person and it experiencing pain. Count Iblis (talk) 01:00, 1 December 2011 (UTC)

It's a theory, one which I used to believe in, but now I've come to doubt it. Now I suspect that consciousness is based on some kind of property of neurons, specifically of conceptualization, which is not itself physical and can thus violate physical laws (like phase velocity which can exceed the speed of light); that the nondeterminism of the universe permits it to adhere to a fixed and immutable fate despite gradual perturbation in a spiritual temporal dimension; that this permits precognition and causality violation (from the perspective of this non-physical quality), which is the active mechanism by which meaningful free will (neither random nor predictable by physical law) is made possible. Now such might be called an algorithm in an extremely broad sense, but (like other quantum-mechanical events) it is not predictable even with perfect knowledge of the four traditional dimensions. Wnt (talk) 01:38, 1 December 2011 (UTC)

Something happened to you which made you renounce materialism? Who did this terrible thing? Were there any other casualties?  Card Zero  (talk) 05:47, 1 December 2011 (UTC)

This differs somewhat from a materialism argument in that I'm not asking whether I'm perceiving matter vs. a property of matter, but whether the seat of perception is matter or some property of matter. In this sense I doubt anyone is a materialist - the atoms and even the molecules in a live versus a dead neuron undergo pretty much the same pattern of thermal jostling, they're exposed to the same electrical charges and noncovalent interactions and so forth, and there's no easy way to explain how countless trillions of atoms know that they're part of one consciousness versus another. The question remains though, is the thing perceiving a stimulus a neuron, a collection of neurons, some kind of esoterically defined informational state summarizing the condition of the neurons? I'm not talking about something mystical here - not exactly, anyway - but something which is not necessarily a "physical object". Wnt (talk) 06:28, 2 December 2011 (UTC)

Sure, but since the question is "do animals run this algorithm", and for that matter "what is the algorithm, and how is it different from a simple robot reacting to a signal from a sensor on its end effector", that fact doesn't clear things up. Wondering what the algorithm might be itself causes me a certain amount of pain.

Besides, as Wnt says, even if we identify that the process is taking place, that doesn't necessarily have any moral significance at all. What is morality for? It might not be for bending over backwards to avoid the carrying out of a particular process ("pain") at any time anywhere. It's probably something to do with society, and probably includes various beings under its umbrella by means of arbitrary cut-off points - currently these arbitrary points are: all humans, from birth (or earlier in certain parts of the world), animals sometimes but not in any very consistent way (we can't hurt them, but we don't have to intervene when they choose to hurt each other, nor do we have a duty to rescue them from "natural" suffering, whatever that is), and pets (by proxy, through their owners - much the same as how you can't mess up the calibration of somebody else's robot). Card Zero  (talk) 05:51, 1 December 2011 (UTC)

Effeminacy

Is Effeminacy an inherited trait over which we have no control or is it acquired due to some psychological conditioning gaffe? — Preceding unsigned comment added by 119.235.51.130 (talk) 13:58, 30 November 2011 (UTC)

Neither. It is a culturally determined thing. The traits that define a person as distinctly "feminine" vary greatly from one culture to another, so I'm not sure you can say that any set of behaviors is universally "effeminate". That is, if you take a person whose behavior defines them as effeminate in one culture, and drop them into another, that culture may not see the behavior as effeminate. --Jayron32 14:05, 30 November 2011 (UTC)

well jayron excess of grace does make a person look feminine... a swaying gait or touch does make him look feminine

That is precisely culturally determined. What's a "swaying touch"? --jpgordon^{::==( o )} 15:55, 30 November 2011 (UTC)

means a graceful touch instead of a normal linear one — Preceding unsigned comment added by 119.235.51.130 (talk) 16:17, 30 November 2011 (UTC)

Precisely culturally determined. Two men holding hands -- obviously effeminate, right? --jpgordon^{::==( o )} 18:09, 30 November 2011 (UTC)

Better -- Obsidi♠n Soul 18:14, 30 November 2011 (UTC)

I think what the poster basically wants is twin studies of transsexuality or perhaps homosexuality or the like. See [2] [3] Biology_and_sexual_orientation#Twin_studies NCBI gave me only PMID 11037086 which I don't know what to do with. I get the feeling from these sources that finding a transsexual with an identical twin is a difficult thing, though perhaps in the age of the Internet this has gotten easier (except that then you'd have self-reporting bias... still no easy project). Wnt (talk) 18:22, 30 November 2011 (UTC)

Except that effeminacy has nothing to do with homosexuality. Not even sure if it has anything to do with transexuality, either. Dominus Vobisdu (talk) 18:27, 30 November 2011 (UTC)

I respect that position; the problem is, if I exclude sexual desires and responses and self-image, I have a hard time defining "effeminate" behavior at all. It is possible as others say above that the term is only meaningful in the context of some specific culture. Wnt (talk) 18:44, 30 November 2011 (UTC)

Jack Benny had some mannerisms that were considered "effeminate", and he was teased about it, regardless of the fact that he was straight as an arrow. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:46, 30 November 2011 (UTC)

See gender role and flamboyance. ~AH1 ^(discuss!) 01:31, 1 December 2011 (UTC)

It seems that masculinity/effeminacy femininity has many components:

1) Cultural.

2) Sexual. That is, most people attracted to men will choose to act effeminate feminine, and most people attracted to women will choose to act masculine, however that is manifested in their culture.

3) Hormonal. Testosterone tends to produce masculine appearance and behavior, and estrogen tends to produce feminine appearance and behavior. The hormone balance you end up with is largely determined by genetics, but diet, medications, and other factors also play a role. Having surgery to remove the ovaries or testes also has an effect. StuRat (talk) 01:40, 1 December 2011 (UTC)

most people attracted to men will choose to act effeminate -- to put it mildly. --jpgordon^{::==( o )} 03:53, 1 December 2011 (UTC)

And do you have a source indicating that most people (or even half) attracted to men will choose to act masculine ? StuRat (talk) 03:59, 1 December 2011 (UTC)

I've no data whatsoever. You've made a pretty bold assertion there, though, that may or may not be accurate. --jpgordon^{::==( o )} 04:18, 1 December 2011 (UTC)

I believe I've made a common sense assertion. So, if you doubt something so obvious, I'd like to see your proof, just as I would if you doubted that 1+1 really equals 2. StuRat (talk) 04:22, 1 December 2011 (UTC)

I'm with jpgordon here. I wouldn't say that people attracted to men are overwhelmingly "effeminate" is something which is necessarily common sense. Even if we limit ourselves to gay males, the majority of gay males don't display overtly "effeminate" behaviors. One generally doesn't describe a woman as "effeminate". She's just "feminine". So, I wouldn't call your assertion StuRat to be common sense. Commonly believed, but not necessarily "sensical". It seems like a very superficial and stereotypical belief about people, but that doesn't mean it should be assumed to be true without any evidence. People once believed that the world was obviously flat... --Jayron32 05:55, 1 December 2011 (UTC)

I'm using "effeminate" as a synonym for "feminine". What does it mean to you ? And "most" does not mean "overwhelmingly", it just means over 50%. I also wouldn't choose homosexuals as the best example, as there they have a conflict between the way the were raised and expected to behave (to be masculine if they are male or feminine if they are female) and the way they may choose to behave on their own. I also still say that the person who argues what is commonly believed is wrong bears the burden of proof. In the case of proving that the world was round, evidence was presented. StuRat (talk) 06:02, 1 December 2011 (UTC)

Commonly believed to be wrong by whom? By StuRat? This is the reference desk, not the place we disprove what random people believe, so it's perfectly resonable to ask people to prove any statements they make without evidence without having to provide evidence their beliefs are wrong. No one has specifically mentioned this but one of the other problems with your claim is you said they 'choose to act effeminate'. Even if they do act that way, how much of it is really a choice? It seems possible they don't really make much of a choice, they just learn to act that way. Nil Einne (talk) 09:32, 1 December 2011 (UTC)

The problem with asking for evidence that common beliefs are correct is that frequently nobody has ever studied them. Has anyone ever done a study to prove that humidity is higher after it rains ? Probably not. As for choice, I don't believe that desires are chosen, but how we actually act is. Anyone can choose to act in ways counter to their natural tendencies. Gay people who are "in the closet" frequently do, for example. StuRat (talk) 14:53, 1 December 2011 (UTC)

They can choose to against their natural tendencies, that doesn't mean when they are acting their natural tendencies they are always or usually choosing to act that way, they may not give enough thought about it that it can be considered a choice. Also there is a load of recorded empirical evidence that humidity is higher after rain, and I strongly suspect someone has studied it so see how different it is, plus it's also something with a well supported working theory behind it. None of this applies to your anecdotal example. Besides that, I don't ask for evidence in the form of peer reviewed articles which have analysed how the majority of people in the majority of cultures choose to act. Can you at least provide reliable secondary sources, which will meet our requirements if you wanted to include your claims in some article? It should be obvious we can easily do that for humidity and rain. Nil Einne (talk) 07:55, 2 December 2011 (UTC)

Let me put it this way. Effeminate men and masculine women are easy to spot, and in most cases if you conclude they were gay you'd be right, but how would you recognize a masculine gay man or a feminine gay woman? You'd very likely conclude they were heterosexual, hence worsening the sampling bias. Case in point, Rock Hudson was pretty much the ideal for masculinity in America for decades, but he was very much homosexual. Jack Benny has already been mentioned. It's like trying to determine what percentage of the population is Catholic by counting how many people wear crucifixes. It's false correlation and a stereotype. -- Obsidi♠n Soul 10:16, 1 December 2011 (UTC)

Just so. My own personal observation -- and I know and have spent much time with many gay men, in the workplace and elsewhere -- is that the effeminate stereotype fits for a noticeable subset, but not by any means most. Most are visually indistinguishable from their heterosexual counterparts. --jpgordon^{::==( o )} 14:44, 1 December 2011 (UTC)

As I've already said, homosexuals aren't the best example. However, since they're a small segment of the population, I don't expect them to change the "most people" balance the other way. Does anybody here seriously believe that the majority of straight men act effeminately or that the majority of straight women ask masculine ? StuRat (talk) 14:55, 1 December 2011 (UTC)

No, but as I noted above, your definition of effeminate is wrong. From the Wikipedia article Effeminacy: "Effeminacy describes traits in a human male, that are more often associated with traditional feminine nature, behaviour, mannerisms, style or gender roles rather than masculine nature, behaviour, mannerisms, style or roles." (bold mine) You cannot redefine a term to meet your own needs, and expect people to then agree with your statement. Effeminate is NOT a synonym for feminine. Females acting like females is called feminine. Males acting like females is called effeminate. They are absolutely and totally NOT interchangable terms, even if you personally, individually, and singularly really want them to be. They just are not. So, when you make a statement "most people attracted to men will choose to act effeminate", as you did, that is incorrect, as women acting like society expects women to is NOT described as "effeminate". That is still the wrong word. If you had said "most people attracted to men will choose to act feminine" you would be more correct. A woman acting effeminate would be a woman acting like a man acting like a woman. Which is still not the same thing as a woman merely acting as society expects women to act; effeminate behavior is not identical to typical female characteristics: it is its own set of unique charcteristics. --Jayron32 15:07, 1 December 2011 (UTC)

Our article is wrong to exclude women. Here are some dictionaries that don't limit effeminacy to males: [4], [5], [6], [7] (see first example), [8], [9], [10]. A Google search on "effeminate woman" yields over 5000 results: [11]. But, since some seem to restrict the usage of the term to men only, I will replace the word with "feminine" in my first post to make it clear. StuRat (talk) 15:29, 1 December 2011 (UTC)

Social context matters a lot. Small subsets of the society demand either a macho stance from men or a more sensitive persona. As a man I know I adapt my behavior to fit in with the group that I am in. For instance I am perfectly capable of addressing the nuances of a cultural entity. But I don't speak up about my interpretation on a cultural topic that might be mentioned if I am among a group of people who would clearly find the observation that I am about to provide to be too loaded with implications of effeminacy. Personally it is a little bit of a conundrum, but I just accept it for what it is, my point just being that one can't just say that effeminacy is an absolute. In fact it varies with the social context, that is, the composition of the people present. On the other hand if I am among creative people or other more culturally aware, or culturally current people—I don't know what language to use—I would would just about be exercising self-ostracism if I did not relate to for instance the finer points of an interpretation of something of basically a "cultural" nature. And this would not be considered effeminate behavior at all in that social setting. Bus stop (talk) 15:39, 1 December 2011 (UTC)

My point number 1 was the cultural impact. Perhaps "subcultural" should be included, as well. StuRat (talk) 16:32, 1 December 2011 (UTC)

I suggest you check your Google search. For me, the first search result is one of those random pages which is a search result page itself [12] which has nothing to do with effiminate woman. The 4rd result is something about 'effeminate "woman-haters"'. The fifth result is 'Effeminate/Woman' and about God not coming in that form. The 7th result is 'soft−cheeked, effeminate, woman−hating man'. The 8th result refers to a 'soft−cheeked, effeminate, woman−hating man' is some sort Greek lexicon where effiminate is given as meaning something akin to 'woman-like' and also 'womanish, feminine' etc. The 9th result appears to be the same thing as the 7th result. The 2nd result refers to an effeminate woman [13], but it's actually referring to a man and says if the phrase be permissable, the man in question was not only like a woman but an effiminate woman. It's also from 1905 (a number of the results seem fairly old although that probably relates partially to the public domain issue). (It's a NZ newspaper so I would guess it doesn't show up under your results.) The 2nd result for the book 'After identity: rethinking race, sex, and gender' is using the phrase in a similar context to you. Primarily I think because the author is trying to make apoint about the ban on same sex marriages as it relates to complementary qualities. Similarly the 10th result is appears to be using the phrase in the way you did although since it's Associated Content, one of those community contributed article sites where random people write stuff for pay and the quality of which people often find questionable. You may want to consider how many of these '5000' search results (and as we've discussed before, precise results over 1000 aren't really that meaningful) are relevant to your point. I think it's clear effeminate is very rarely used to refer to a woman. Nil Einne (talk) 07:55, 2 December 2011 (UTC)

Is it possible for Man to destroy the Sun?

Is it possible for Man to destroy the Sun? 205.156.136.229 (talk) 14:43, 30 November 2011 (UTC)

No. -- kainaw™ 14:47, 30 November 2011 (UTC)

Short answer: No. Long answer: Maybe, if we could create a black hole with a powerful particle collider and somehow get that in the sun (perhaps a space-built particle collider). Goodbye Galaxy (talk) 14:59, 30 November 2011 (UTC)

Don't try this at home. -- Q Chris (talk) 15:23, 30 November 2011 (UTC)

If we somehow managed to create a micro-black-hole with a mass of one ton, the Schwarzschild radius would be about 1.5×10^-24m. That is roughly one billion times smaller than the radius of a proton (as far as one can assign a radius to elementary particles). The black hole will dissipate its energy due to Hawking radiation in about 0.000000085 seconds. The energy release is about equivalent to 20 Gt of TNT, or about 400 Tsar Bombas going of at once. You would need to stuff 11764705 tons of material per second through a hole that is a billion times to small for a proton, and all that against the radiation pressure of the above mentioned 400 Hydrogen bombs (not per second, per 0.000000085 seconds!), just too keep your micro black hole the same size. I think we can put this beyond the realm of science fiction. --Stephan Schulz (talk) 15:49, 30 November 2011 (UTC)

Further, the question asked if man can destroy the Sun, not a black hole. No matter how you fling a man at the sun - even if you send all the men at it at once, the Sun won't be destroyed. -- kainaw™ 15:52, 30 November 2011 (UTC)

Sure you can. You just have to throw the poor bastard hard enough. See Relativistic kill vehicle. ScienceApe (talk) 20:18, 30 November 2011 (UTC)

I thought about this, but I'm not sure that would work for the sun. I would expect the relativistic man to fly straight through the sun, and out on the other side, taking nearly all of his kinetic energy with him, and leaving a trivially small tunnel in the sun behind him that would be immediately closed by gravity. --Stephan Schulz (talk) 00:18, 1 December 2011 (UTC)

Probably. You can increase the amount of energy transferred by making him blow up into tiny bits before he hits though. ScienceApe (talk) 13:49, 1 December 2011 (UTC)

What if you had a lot of tinfoil on your hands? Super duper duper thin, reflective, heat resistant (alright, maybe not literally tin), and you unwrap it in a shell around the Sun. Call it a Dyson sphere or something. Can you heat up the outer layers of the Sun enough that they start flying off into space? (I mean, much more than they already do as solar wind) Wnt (talk) 18:15, 30 November 2011 (UTC)

What a waste of good hat-making tinfoil.-- Obsidi♠n Soul 18:19, 30 November 2011 (UTC)

Interestingly the sun has negative heat capacity so your tinfoil would actually cool down the sun's outer layer making it expand. Dauto (talk) 18:47, 30 November 2011 (UTC)

I know that's true at equilibrium, but according to Sun that equilibrium is on the order of 30 million years. If you just string up some tinfoil over the course of, say, 10,000 years, I think the outer layers would get hotter. (I'm sure it's all very clear in the math shown in virial theorem; I'll look over that... any time now...) Wnt (talk) 19:06, 30 November 2011 (UTC)

No, they would get cooler. Virialization happens much faster than you describe. Dauto (talk) 19:13, 30 November 2011 (UTC)

I'll take your word for it. ;) Wnt (talk) 19:15, 30 November 2011 (UTC)

He said is it POSSIBLE, the answer is yes, but we don't have the technology to do it any time soon. Turning it into a black hole seems to be the best route to do it. ScienceApe (talk) 20:17, 30 November 2011 (UTC)

Maybe it is possible to intervene to cause the sun to undergo a super-nova. Perhaps by seeding it with lots of heavy metal elements to age it prematurely for a star of its mass. If you found a large enough clump of antimatter that would suffice too if it could be maneuvered to collide with the sun. SkyMachine (talk) 21:12, 30 November 2011 (UTC)

I don't think dumping heavy elements would work well. Even if nuclear fusion stops at the core of the sun suddenly it still takes thousands of years for it to collapse and go supernova. ScienceApe (talk) 00:03, 1 December 2011 (UTC)

Time involved is a minor problem as physical imortality is an easier technological solution to achieve than stellar engineering. SkyMachine (talk) 08:29, 1 December 2011 (UTC)

Maybe self-amplifying lasers using energy equivalent to a sizeable fraction of the Sun mounted on Dyson spheres at resonant frequencies aimed at the sun would cause its internal pressure to exceed its gravity, causing an explosion. Or maybe a relativistic nuclear-antimatter device that uses chain reactions and sets off a reaction enveloping the entire Sun could work, too. Don't try that at home, either. ~AH1 ^(discuss!) 01:28, 1 December 2011 (UTC)

Even destroying only the Earth alone (as a planet, not as a biosphere) is hard enough to be considered impossible by our technological level, and most probably continue to be so for quite a long time. — Preceding unsigned comment added by 91.23.225.204 (talk) 22:29, 1 December 2011 (UTC)

Wood not decomposing after 400,000 years?

How is it possible for wood to remain non-decomposed after 400,000 years (see Schöningen under "History" section of article) ? 129.2.171.55 (talk) 15:14, 30 November 2011 (UTC)Nightvid

Anaerobic conditions. The Schöningen spears were waterlogged and buried under layers of plant material and anoxic mud in a former bog. In addition to being oxygen-starved, peat bogs are highly acidic, a result of tannins from plant tissues - common antimicrobial chemicals found in plants (and used also for tanning/preserving leather, hence the name). As you can guess, this environment is very hostile to decomposing bacteria and fungi. There are similar discoveries in peat bogs in other parts of Europe, including very well preserved human remains (bog bodies, like the Tollund Man).

Other reasons for wood to be preserved (or at least be readily identified as such) are carbonization (being charred or burned results in inorganic carbon which is less appealing to bacteria and fungi), permineralization (being petrified), mummification (being subjected to extremely cold or hot environments with very little humidity, like in permafrost or desert sands), and as impressions and other indirect evidence like remains of attachment points or organic "smears" of dead bacterial colonies where the wood they'd eaten away once existed (in paleontology, these are known as trace fossils).

There are also much older perfectly preserved wood than the Schöningen spears, like the 2-million-years-old remains of trees buried in a landslide found in Ellesmere Island. These were not permineralized, but are actual wood. They were mummified by the extremely harsh environment of the Arctic during the onset of a glacial age in the Pleistocene.-- Obsidi♠n Soul 15:51, 30 November 2011 (UTC)

Note that for petrified wood and fossil wood, the original carbon-based molecules have been replaced by silica minerals, and can last almost indefinitely. ~AH1 ^(discuss!) 01:22, 1 December 2011 (UTC)

Is there a quantum of mass?

Or rather, a theoretical minimum for a measurable quantity of mass? Like the planck length, but for mass (and not the planck mass!) Goodbye Galaxy (talk) 15:55, 30 November 2011 (UTC)

Yes, if the Compton wavelength is larger than the size of the observable universe, then the mass can't be determined accurately. Count Iblis (talk) 16:29, 30 November 2011 (UTC)

Heh, um, what? (I tried reading the article on Compton wavelength but it's not very comprehensible). --Goodbye Galaxy (talk) 17:01, 30 November 2011 (UTC)

Quantum mechanics: all particles are actually something of a wave. Until you actually bump into one and say "hey, look, a wave just hit me right here right now", the wave is in this spread-out state (you can think of water if you want). If the amount that it's spread out is larger than the universe, what is observable, then there might as well have been no wave at all (like if on the ocean you had a wave whose crest spanned the entire ocean - then that's just sea level - it's no longer meaningful to call it a wave).

The Compton wavelength is a nice quick measure of the wavelength (spread) of a particle, and the span of the universe can be super-approximated by its age T times the speed of light c (the limit of what's observable). Put it all together: mass > h / (c² × T_universe) ≈ 10^-68 kg. Wow. I'm thinking that's off by a square, but since the upper limit on neutrino mass is about 10^-36 kg, this seems a decent starting point. SamuelRiv (talk) 18:53, 30 November 2011 (UTC)

Lets back up three setps and approach this from a simpler point of view. Mass is energy. Two names for the same thing. See mass-energy equivalence. Energy is quantized, ergo mass is quantized. QED. --Jayron32 20:59, 30 November 2011 (UTC)

And what is the quantum of energy? I'm having trouble finding it. Goodbye Galaxy (talk) 21:40, 30 November 2011 (UTC)

Energy is not quantized. In some systems the energy levels form a discrete set (e.g. the bound states of electrons in atoms), in others they form a continuum (e.g. kinetic energy of free electrons). Also, mass and energy are not the same thing.--Wrongfilter (talk) 22:39, 30 November 2011 (UTC)

For the smallest mass, you could start by looking at the smallest known particles that have mass: electrons, leptons, quarks, muons and possibly gluons. Perhaps for photons the mass-energy equivalence will yield a quantum mass from its inherent energy? ~AH1 ^(discuss!) 01:19, 1 December 2011 (UTC)

It is possible to find the particle with the smallest rest mass in the standard model. But that is not really a quantum of mass, as (AFAIK) the other particles are not a multiple of that mass, nor (AFAIK) is there some clear common unit mass, of which all particles are multiples. Also rest mass is not the only game in town... 88.112.59.31 (talk) 02:14, 2 December 2011 (UTC)

Stars: death, birth, spreading, clumping

Thread retitled from "How could the spread out remains of dying stars spread over multiple light years result in sufficient density to start clumping for a new star?".

How far apart do scientists estimate was/were the dying star(s) that supplied the elements that comprise our sun, planet, and us? With stars so far apart and expansion of space (as I understand it) carrying things further away still, it would seem to be a low probability occurrence for sufficient quantities of elements blown out from across many light years to accumulate to birth a star system.

And another related question, it would seem that when a star went supernova and blew heavier elements in all directions, that would result in mass densities for future star nurseries far away from the dead parent that were much lower than what the parent had, so won't favorable conditions for star births monotonically decrease? 20.137.18.53 (talk) 17:13, 30 November 2011 (UTC)

The answer is basically gravity. If a star is large enough when it explodes, it's possible that its supernova remnant could still be dense enough to form smaller stars eventually. Otherwise, the stellar dust will fly out into space, orbiting the galactic centre until it clumps up with other dust clouds from other stars, potentially creating enough density to form another star. Note that universal expansion only really applies between galaxies, not within them. Goodbye Galaxy (talk) 17:24, 30 November 2011 (UTC)

(e/c) Remember that virtually all stars form within galaxies, and galaxies are self-contained systems. i.e. It's not stars that are drawing apart from each other, it's galaxies. Matter from a supernova within a galaxy really has nowhere to go but back to the galaxy itself, and galaxies (far more rapidly during the earlier ages of the universe) also capture gas wandering through the intergalactic space like vacuum cleaners. Nevertheless, when hydrogen within the galaxies run out, the galaxies themselves start to die. See Galaxies are running out of gas (Katy Storch, Cosmos Magazine). -- Obsidi♠n Soul 17:50, 30 November 2011 (UTC)

I believe another effect is that the ripples created by novae or supernovae can cause existing clouds of gas to clump together, and this "seed" can gradually grow and pull in gases from the supernova, too. StuRat (talk) 18:11, 30 November 2011 (UTC)

I am revising the heading from "How could the spread out remains of dying stars spread over multiple light years result in sufficient density to start clumping for a new star?" to "Stars: death, birth, spreading, clumping". (See WP:TPOC: "Section headings".)

—Wavelength (talk) 18:18, 30 November 2011 (UTC)

Take a look at stellar evolution and protostar. Ripples in supernova remnants often acquire enough local density to become a gravitational hot-spot, attacting ever more mass as it rotates and falls toward its own centre of mass. When enough heat is generated to start nuclear fusion (formally 8% of solar mass), the star has a chance to blow off the surrounding gases and create a partial vacuum. By nature star formation is very chaotic, and typically occur in nebulae, possibly interstellar gas and even more rapidly around supermassive black holes, where gravitational attraction alone is enough to produce significant clumping. ~AH1 ^(discuss!)

Something else that needs to be appreciated is the vast scales of time involved. That is, while the gravitational attraction of particles of a cloud spread out over light years seems insignificant, and is on human timescales, over billions of years it can become quite significant and pull the cloud together to form stars. StuRat (talk) 01:29, 1 December 2011 (UTC)

this is my favorite subject, ok. [[akbar mohammadzade]]:the supernova explosion cases main star body to escape with 1000Km/s so the remnant nebula will expand very fast(coming here from alphacenturi after 1300years) , this means one parcel of matter will be after 300 years at distance of one light year ,our solar system fathering supernova supposed that was at 15 light year distance of our global Orion cloud , so the parcel which made our body elements specially terrestrial planets came here after -about 20000 years very short time in astronomy-the speed of separating was measured for crab nebula] .[[akbar mohammadzade ]]--[[Special:Contributions/78.38.28.3|78.38.28.3]] ([[User talk:78.38.28.3|talk]]) 09:51, 1 December 2011 (UTC)

Only I can say that we are working on some new ideas about formation of stars specially galaxy formation, we have some difficulties in existing theories of gas dynamic.akbar mohammadzade --Akbarmohammadzade (talk) 10:15, 1 December 2011 (UTC)

"First Human"

Hey guys, I just wanted to ask a quick question. I believe in the theory of evolution, but I'm having trouble understanding something. When our common ancestor became human, would he have to mate with some other human to produce more human children and keep the species alive. But there weren't any other humans when one of the common ancestors became/produced a human child, and thus he would have to mate with one of our common ancestors. But wouldn't cells of a first human and our common ancestor be different, and thus the reproduction couldn't happen? 64.229.180.189 (talk) 21:06, 30 November 2011 (UTC)

There isn't some magic single person who would be the "first person". You need to think of it more as a continuum rather than a magic event. That is, at no point does a single organism become a new species different from that of its parents; what instead happens is that, as populations (large groups capable of interbreeding) breed over time, their genetic and physical makeup will gradually change as the environment in which they live changes to favor certain traits. Evolution happens in fits and starts; a population may remain relatively stable for a long time, then change relatively quickly. There isn't a "hard and fast" line where a new species is said to exist (there isn't even a good definition of what a "species" is!), but in general, when a population has become genetically different enough that it could no longer interbreed with another population (either a contemporary one, or an ancestral one) it could be considered a distinct species. But that sort of thing isn't defined by a single birth of a single individual; it is a slow and gradual thing (at least, on a human timescale). If you are interested in reading up more on the idea, see Speciation for more details on how new species may arise. --Jayron32 21:14, 30 November 2011 (UTC)

Richard Dawkins addresses this in his book The Magic of Reality. As long as individuals (of oposite sex) are of the same gene pool they can mate and produce viable offspring. To speciate there needs to be physical isolation between 2 descendant populations of this original gene pool for long enough for genetic drift and different selection pressures to make the 2 descendant gene-pools different enough that crossed-offspring are no longer viable, and this usually takes several thousands of generations. So (assuming you are a man) if you had a time machine and felt randy (grandfather paradoxes aside) you could go back and father children with women for several tens of thousand generations prior to your own before these offspring started to die without being able to go on and breed themselves. SkyMachine (talk) 21:51, 30 November 2011 (UTC)

A fascinating phenomenon which illustrates some of these points is ring species. When I learned about this, it made the idea of speciation a lot easier to grasp. Vespine (talk) 22:04, 30 November 2011 (UTC)

Actually, this is more of a language problem than a science problem; the thing is that most of the words we use every day don't have strict yes/no definitions but rather describe a continuum without clearly defined borders. This is a very old, very common and, if I may add, ultimately very pointless problem in the philosophy of language. Consider the pile of sand paradox for a classic example: you have a pile of sand and start removing single grains one after another. At some point, your pile stops being a pile and becomes a loose association of grains, and at some point you end up with a single grain of sand. Now, when did your pile stop being a pile? After you removed the 1.000th grain? The 1.001st? The problem is that you can't clearly define how many grains make a pile, and speciation works not much different from the pile of sand. There's nothing really mysterious about it, it's just the way language works (even though we would like to have clearly definable terms for everything, in reality that's just not possible because "pile" or "species" or "planet" or whatever are just arbitrary concepts we try to force on reality - and of course I'm intentionally using "planet" as an example because lumps of matter floating in space are just lumps of matter floating space and don't care very much whether we call them "planet" or "moon" or "asteroid" or whatever) -- Ferkelparade π 22:05, 30 November 2011 (UTC)

(ec) I found Ring species really useful for understanding this, although our article starts unhelpfully for a new reader. I suggest starting with the section "Larus gulls". 86.164.60.202 (talk) 22:08, 30 November 2011 (UTC)

Another helpful way to think about this is to make an analogy with evolution of languages. Did the first English speaker find himself unable to find anybody to speak with because all his ancestors were not speaking English? Dauto (talk) 22:39, 30 November 2011 (UTC)

• It is not helpful to think in terms of first speaker, first human or first member of the species. Helpful is not to think on terms of someone being the first. Quest09 (talk) 14:16, 1 December 2011 (UTC)

Isn't that what I said? Dauto (talk) 17:05, 1 December 2011 (UTC)

Incidentally not. Evolution of languages in not comparable with evolution of species. In the case of languages there is possibly a first member, Many scientists defend the idea of instantaneous emergence of language in 'perfect' or 'near-perfect' form is, but none consider any species arising spontaneously. Quest09 (talk) 20:50, 1 December 2011 (UTC)

I studied linguistics, and I'm not aware of any scientist saying that, unless you count artificially constructed languages. There's no "perfect" form for a language. thx1138 (talk) 22:41, 1 December 2011 (UTC)

There's also another easy way to summarize everything said in a single sentence (particularly Jayron's post): individuals do not evolve, populations do." -- Obsidi♠n Soul 00:28, 1 December 2011 (UTC)

Don't forget about horizontal gene transfer through viral fossils, which can help a species evolve from one to the next (via epigenetics). ~AH1 ^(discuss!) 01:08, 1 December 2011 (UTC)

Horizontal gene transfer is basically just the acquisition of new genetic material that is not from an ancestor. It's comparable to mutation in which an individual also suddenly acquires genetic material very different from the rest of the population/species it belongs to. An individual which acquires new genetic material through those kinds of processes is not automatically a new species. The changes need to be positively selected in the individual's population for the population to effectively evolve. In most cases, they are lost after several generations. It's like being gifted a new tool that you can try out to see if it helps or makes things worse, as opposed to gradually developing the tool yourself.

However, yes, in organisms that are capable of asexual reproduction, an individual that acquires novel genes through these process can effectively give birth to a new population very different from its parents (a classic example is the evolution of antibiotic resistance in Staphylococcus aureus). Horizontal gene transfer is actually a very important and very prevalent mechanism in prokaryotic evolution, as opposed to higher animals. However, populations that originated like this are properly strains, not species, because in virtually all cases, they have not acquired reproductive isolation yet. -- Obsidi♠n Soul 09:16, 1 December 2011 (UTC)

These guys have this well in hand, but the moral of this story is that when you look at a tree of life, the branches have a certain "thickness". There is a single last common ancestor, yes, but his contribution to any given genome is absolutely miniscule. While the story of Adam and Eve is deeply rooted in the Western psyche, in genetic terms, this is known as a population bottleneck. A species subjected to any such narrow passage loses so much of its rich gene pool that it is difficult for it to adapt to any change in environment, or even to survive in an existing one (See cheetah). One consequence of this is that when species are subjected to extreme changes in environment, as is happening today, they often blur old boundaries and hybridize freely, gaining an advantage by having a wider pool of genes to draw upon. The emergence of hybrid species represents a real ecological problem for us, because of things like West Nile Virus spreading from birds to humans because the human-biting and bird-biting mosquitoes started cross-breeding. I wouldn't be overly surprised if it turns out that some previous advance in human evolution likewise emerged from a hybrid population at a time of stress, though such a thing would be very difficult to prove. So the branches of the tree of life are not merely thick, but in certain circumstances can branch apart, fuse back together, then branch out again. Wnt (talk) 02:05, 1 December 2011 (UTC)

Reminds me of an old joke that goes like this: College anthropology professor (pointing to a chart on the board showing the human tree of evolution): "As you can see from this diagram, the first human ancestors were a species of apes known as Australopithecus." A student (raising his hand): "But, Professor, the priest at our church says that the first human ancestors were Adam and Eve. How can you explain this?" Professor (completely unfazed): "And why do you think that apes couldn't have been named Adam and Eve?"  :-D 67.169.177.176 (talk) 03:04, 1 December 2011 (UTC)

Because Australopithecus hyoid bones were more ape-like than human-like. Their names were more likely to have been *Yawn* *Sniff* and *Grunt* *Grunt*. :D -- Obsidi♠n Soul 10:47, 1 December 2011 (UTC)

I thought it was pretty well established that humans did go through a fairly serious population bottleneck (although obviously not as serious as two people!), probably about the same time as most of the other hominids died out. And that non-African humans, at least, are indeed hybrids in that our ancestors bred with neanderthals. I may be misreading your comment, Wnt, but it sounds like you're saying these are only suggested ideas, rather than pretty firmly established theories supported by lots of evidence and widely held in the field? 86.164.60.202 (talk) 14:20, 1 December 2011 (UTC)

I was actually saying humans didn't go through an Adam-and-Eve style bottleneck without addressing what bottlenecks did occur (which weren't so severe, as evidenced for example by the range of blood and tissue types maintained to the present day). And while humans did hybridize to some extent with Neanderthals, I haven't actually seen evidence that this contributed to their adaptation to local environments, though it has been suggested and it seems very possible. (Also it still isn't universally accepted that Neanderthals were a separate species; the main argument for that was that they didn't interbreed with humans...) Wnt (talk) 22:06, 1 December 2011 (UTC)

Comment: I assume there had to be a single first individual with a fused chromosome (Chromosome 2), who had offspring with only 23 chromosomes, who then intermixed with the general population having 24. --George100 (talk) 04:34, 2 December 2011 (UTC)

As explained here, the human chromosome 2 is essentially a Robertsonian translocation of two chimp chromosomes. Now Robertsonian translocations in contemporary modern-day humans are actually pretty common, about 1 in 1000 according to the article. There are problems with them - some people carrying them have developmental delay, and many will have problems producing children (i.e. frequent miscarriages) when breeding with people who don't carry the translocation. Still, there's a random chance in any given small population that a translocation will randomly become the only form of the chromosome left (fixation (population genetics)). That is unlikely but not impossible - but it is also possible that some phenotype of the fusion happened to be positive. Contemporary Robertsonian translocations can lead to "developmental delays", to use a particularly inept euphemism ([14]); the fact that such regulation of mental development is prone to alteration by this mechanism illustrates the possibility that some particular translocation might have turned out the be beneficial. Still, a translocation with a large effect would be unlikely to be beneficial. The bottom line is that this first individual with a fused chromosome would probably not be observably different from others of his species at the time, and very probably not very much so. Wnt (talk) 06:14, 2 December 2011 (UTC)