Wikipedia:Reference desk/Archives/Science/2012 June 15

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June 15

Buoyancy and pressure

Hi, if I took an object that normally floats to the bottom of a deep ocean at some enormous pressure, then, ignoring the fact that the water might be very slightly compressed and therefore very slightly denser, and assuming the object itself is incompressible, am I right in thinking that the buoyancy of the object would be exactly the same as very near the surface? In other words, pressure alone does not make any difference to buoyancy? 86.160.221.194 (talk) 02:57, 15 June 2012 (UTC)

You are correct, as the buoancy comes from the object's volume displacing that amount of water (providing that no part of the object projects above the water surface). If both the object and the water are incompressible, then the difference in mass between the object and the water that would fit within its volume will always be the same regardless of depth or pressure. Ratbone58.164.224.145 (talk) 03:07, 15 June 2012 (UTC)

"clear" safety glasses

My "clear" safety glasses I bought are not really "clear" in that they are not as clear as glass. Are there any that are actually clear. They are hard to see through you cant see detail well. It also seems light dosent pass well and it seems dark. --Wrk678 (talk) 05:55, 15 June 2012 (UTC)

I remember when I first had to wear safety glasses at work. I was not happy with them either - it is hard to define exactly why, but they didn't seem as clear as I thought they should be. But objective testing, such as reading fine print or looking at leaves on a distant tree showed that in fact they did not affect sharpness. And after wearing them a week or so I got used to them. I think part of the problem is that they don't have any anti-reflective coating like spectacles usually do. At least in Australia, all safety glasses are the same as to quality of vision. In some fields of employment, such as electronics lab work, assembly, and servicing, most employeers will permit wearing only prescription spectacles, provided that the lenses are shatterproof. This is what I wore on the job, with various employers, ranging from electronics servicing, lab work, and light machine shop work - for other work I had to wear a full-face safety mask. In some cases they will also stipulate that side wings are fitted, so that wire offcuts and the like cannot enter your eye from the side. Spectacle shops usually don't stock side wing frames, but they can order them in for you. Presciption spectacles will of course give you the best possible vision, especially if made with low refractive index lens material (not to be confused with the lens power). Check with your employer. If your supervisor is not aware that prescription specs fitted with side wings are ok in your industry, then provide him with evidence. Ratbone121.215.129.221 (talk) 07:01, 15 June 2012 (UTC)

I dont wear prescription glasses

Depending on why you need them, different types of safety glasses may be appropriate:

1) For potential high velocity objects, say if you are working with a chainsaw, you need the best ones.

2) If you only need to protect against dust, then you can get by with soft plastic goggles, which should be easier to see through. (If they get scratched, replace them.) StuRat (talk) 16:25, 15 June 2012 (UTC)

Are there different levels of opaqueness or something? A couple years ago I bought some safety glasses which were the hard plastic type and they were much more clear to see-through than the ones I have now. It also seems that there is a big problem with the light coming through the glasses it seems like they restrict light I don't understand why that would be the case if they are actually clear.--Wrk678 (talk) 00:35, 16 June 2012 (UTC)

Did you get, by mistake or some other reason, lenses that were tinted for some special application? Ratbone120.145.193.114 (talk) 01:32, 16 June 2012 (UTC)

Tempered glass may have different optical properties from normal glass, due to doping the glass with other chemicals. StuRat (talk) 03:29, 16 June 2012 (UTC)

Tempered glass is essentially stress-relieved glass, as the Wiki article says, achieved by special thermal processing. As such it should have better optical properties. Stress results in inconsistent refractive index and increased attenuation. Wickwack124.178.50.166 (talk) 06:01, 16 June 2012 (UTC)

There's also a chemical process where they replace sodium with potassium in the glass. How does that affect the optical properties ? StuRat (talk) 06:55, 16 June 2012 (UTC)

Ontogeny recapitulates phylogeny

I'm not a biologist but I can't believe that ontogeny is no longer used as a valuable though not infallible source of clues for things to check on when investigating phylogeny, much as some modern highways parallel older roads, with some shortcuts and changes. The article says the theory is defunct. I think it can't be defunct, except if it's taken to be infallible. 1)Am I wrong, is "Ont recaps phyl" never absolutely never of any use to real scientists? or: 2)Is the article's claim just the latest oversimplification put into introductory textbooks and transferred to wikipedia?Or: 3)Is it also an effort by creationists to undercut evolution status as a well established theory?--Rich Peterson76.218.104.120 (talk) 09:25, 15 June 2012 (UTC)

I think you misunderstand the distinction between comparative embryology and ont-recaps-phyl. Ontogeny itself is absolutely still studied, and gives valid if imperfect predictions of the evolutionary relationships of different organisms. You can compare the two as so: Comparative embryology would predict that in looking at the embryos of a mouse, an ape, a human, a frog, and a fish, you can construct a phylogeny of the organisms based on ontogenic similarities. Recapitulation theory, on the other hand, would predict that in looking at the embryo of a human, it would actually resemble at various times a fish, an amphibian, a rodent, an ape, and then finally a human. The confusion may have been caused by subtle wording issues. Ontogeny can construct a phylogeny. It does not recapitulate it (physically manifest as it). Someguy1221 (talk) 09:45, 15 June 2012 (UTC)

i'm sure, as i did suspect, and indicated above, that what you say is true. But i'm talking about what the current wikipedia article says.(thanks for pointing out the real title is recapitulation theory) Also, is it really standard in current scientific literature to refer to the "infallible" version as recapitulation theory, rather than something like "strict form of ontogeny recapitulates phylogeny"?--It seems like a hijacking of terminology, another reason why i suspect creationists are partly behind the article.--Richard Peterson76.218.104.120 (talk) 10:11, 15 June 2012 (UTC)

The OP is already posting [1] at the article Talk page[2] which is shared by openly declared creationist(s) and others. There is no need to "suspect creationists" or to divert a discussion of the article's subject to this desk. DriveByWire (talk) 11:05, 15 June 2012 (UTC)

I like Haeckel, and I think the idea, as a very general and quite fallible rule of thumb, is far from useless. It was taught in classrooms long after evolution was accepted as fact. It can be seen as related to the notion of heterochrony as a method of evolution. For example, consider tunicates in comparison to vertebrates and other chordates. Probably tunicates are not basal to the phylum - rather, they have added a stage at the end of their development during their evolution, transforming from a vertebrate-like creature with a notochord to a sessile pumping sack. But it is also possible that they are in fact basal, and the rest of us have lost the sessile stage, like axolotls. Now, Haeckel's rule of thumb would argue in favor of the first version, which is now finding favor from other data; that's the sure sign of a good rule of thumb. But we can't rule out the second idea either. (It might yield interesting biomarkers for, say, the tenured professor) Wnt (talk) 14:36, 15 June 2012 (UTC)

{{{Thanks to all who have responded so far. DriveByWire,after doing an initial edit on the article recently, i decided i wanted clarification on the status of ontogeny vs. pjylogeny. Ijust wanted to learn something the article wasn't supplying, so it was appropriate for me to ask it here. My suspicion that the article was misleading was confirmed by the reply of the obviously knowleadgable Someeguy1221 (and later by the obviously knowledgeable User:Wnt. A few minutes after replying to Someguy1221 I decided the article badly needs someone knowledgeable to work on it, and yes I did suspect creationists had been working on it. So I put up an expert needed tag. But what do you mean I don't I "need" to suspect that about creationists? Do you mean I shouldn't say so, or that it's obviously true, or NOT true, or what? I'm not saying you're wrong, I just want to know what you mean. Best wishes, Richard L. Peterson76.218.104.120 (talk) 23:17, 15 June 2012 (UTC)

Creationists are as welcome as all other editors to work consensually on Wikipedia articles, but do you disagree Richard? I mean that when something is true, you know it is true, you are free to say it is true, but you no more need to say you suspect it to be so than anyone needs to say they suspect that their feet are partly behind an effort to make them walk. When you say what you suspect, consider the etymology of such a tendentious word: suspicion late 13c., from Anglo-Fr. suspecioun, from O.Fr. suspeçun, sospeçon "mistrust, suspicion" (Fr. soupçon), from L. suspectionem (nom. suspectio) "mistrust, suspicion, fear, awe." DriveByWire (talk) 16:43, 16 June 2012 (UTC)

But i didn't know it76.218.104.120 (talk) 02:37, 17 June 2012 (UTC)

Clarification: I suspected 2 things. One was that a less strict form of recapitulation theory was far from defunct. This was confirmed by a couple responders above. I also, as I was writing my first post above, started guessing about the current article's tone and began to suspect that a creationist agenda was controlling it.But I didn't know that.... Of course, all are welcome to contribute, but it is preferred that the overriding agendas for any contribution are fairness, balance and verifiability.76.218.104.120 (talk) 06:46, 17 June 2012 (UTC)

You didn't know? If you had bothered to read the Talk page for the article you would have plainly seen an editor declaring "I'd better state first that I am a creationist." You could have saved yourself some time by doing so. The Wikipedia guidelines on fringe theories, but not anyone's imagined "agenda to control", apply to the article. It seems silly to politicise the ORP slogan as a stance in an evolution vs. creation debate because the features seen (or not seen) in embryo development can be accomodated by either viewpoint i.e. the subject is not pivotal in the debate. In my opinion no credible debate even exists, but that does not justify a witchhunt for holders of a minority theory that you suspect are infiltrating Wikipedia articles. It does not look like this desk can help you with any futher references beyond the article you already cited. DriveByWire (talk) 00:59, 18 June 2012 (UTC)

So Rich imagined creationists controlling the agenda and DriveByWire imagined Rich going on a witchhunt? Can't we all just put our imaginations down and get along? 203.27.72.5 (talk) 02:30, 18 June 2012 (UTC)

A theory about alternate timelines

Is there a theory which states that every time a decision is made, one or more parallel timelines split? I'm aware that there is a theory where changing the past results in an alternate universe, but what about alternate timelines? Narutolovehinata5 ^tccsdnew 14:03, 15 June 2012 (UTC)

Many-worlds interpretation Wnt (talk) 14:36, 15 June 2012 (UTC)

Thanks. Narutolovehinata5 ^tccsdnew 14:43, 15 June 2012 (UTC)

Resolved

Many-worlds interpretation isn't about humans making decisions, its about quantum effects that can have multiple, unpredictable outcomes. thx1138 (talk) 16:21, 15 June 2012 (UTC)

These are not unrelated. There are only two possibilities that fit within existing physical theory:

1. Human decision-making is a deterministic process; there is no free will
2. Human decision-making is affected by quantum indeterminacy

If option 2 is true, then the many-worlds interpretation says that every decision you could have made actually occurs, in an alternate "world". This is less fantastic than it may seem, and should not be any more surprising than any other quantum paradox. (Schrödinger's cat, for example)--Srleffler (talk) 17:37, 15 June 2012 (UTC)

(edit conflict) Well, only in the sense that any possiblity of anything at all exists in an "alternate world". At an given instant, an atom may decay or it may not, a virtual pair may form spontaneously or it may not, etc. etc. Every possible, but not yet occured, physical change from the way the universe is this will happen in one of a near infinite number of universes which will be created in the next instant, and so on and so on. Since humans exist and are made of matter, they're part of that too. --Jayron32 17:58, 15 June 2012 (UTC)

That's a rather common but fallacious dichotomy. Volition is the faculty that allows higher animals to act when outside factors do not determine their choice. For example, you can either stay in bed or get out, exit on the left or the right--whereas plants merely grow toward the sun given the proper external stimulus. That is volition, or will, and it is why Buridan's Ass doesn't starve. The freedom of the will is not the freedom of the body from physical reality or the freedom of the self from the body, but the moral freedom of the volition from the coercion of others. If a criminal ties you to the bed you are not staying in the room of your own free will. You are your body, so it is absurd to argue that it wasn't you who chose to do something, but your body. (That's setting aside organic disorders that interfere with the proper functioning of your volition.) μηδείς (talk) 17:54, 15 June 2012 (UTC)

The sticking point is the "you are your body" part of it. In my opinion there is no possible satisfactory materialist account of free will. I am a hardcore incompatibilist on this point. --Trovatore (talk) 00:40, 16 June 2012 (UTC)

Well sure, that's like saying there's no satisfactory quantum physical explanation of sexual selection, or no chemical explanation of the electoral college. Of course there isn't. They are on different levels of explanation. The problem is the bizarre insistence on materialism as explaining anything but chemistry. What is the molecular weight of a shadow? What is the electrical valence of truth? These questions reveal the essential fallacy of category errors.

No, that's not my point at all. There is no acceptable account of free will that does not reject materialism, that does not say materialism is false. --Trovatore (talk) 01:00, 16 June 2012 (UTC)

I don't quite understand your statement. I hold that there are such things as true statements and good actions, and I don't hold that the truth of a statement or the morality of an action can meaningfully be reduced to chemical equations. I will assume you both understand and agree with that? μηδείς (talk) 01:12, 16 June 2012 (UTC)

I am saying that if there is nothing beyond the physical universe, then there is no morality or meaning, and nothing matters at all. Fortunately, there is something beyond the physical universe. --Trovatore (talk) 01:27, 16 June 2012 (UTC)

The laws of physics allow unversal computing devices to exist which can thus run any type of algorithm that can implement whatever (inexact) moral laws you can imagine. Count Iblis (talk) 02:28, 16 June 2012 (UTC)

But if there is no one inside to be aware of them, who cares? --Trovatore (talk) 02:33, 16 June 2012 (UTC)

That depends on whether your choices really were the result of free will, or whether or not you merely have the delusion of free will; that is every action you take was predetermined, but your mind makes you think you had some control over it. The trick is deciding how to tell the difference. Which is not to say that I agree or disagree with you, but the difference between believing that you could have made a different choice in any action you take, and actually haing had the choice, is an interesting philosophical problem. --Jayron32 17:58, 15 June 2012 (UTC)

Mηδείς, the dichotomy is not at all fallacious in the context of the question we are discussing. Ignore all the philosophical questions about freedom of will, volition, etc. Assume decision-making is a purely physical process (i.e. no immaterial soul). There are only two possibilities, which I enumerated. One is that the process is purely deterministic, in the sense used in physics. In that case, there is no splitting of timelines. It's not clear that this is the case, however: we know that our universe is not deterministic in this sense: quantum mechanics demonstrates that there is true, irreducible randomness in the universe, and that things can exist in more than one state at a time. Usually these effects are observable only on microscopic scales, but they are not always limited to such small scales. It is possible that human thought is affected by quantum randomness, that when we make at least some decisions, quantum uncertainty could affect which choice is made. If so, then the many worlds interpretation applies—each choice that was affected by quantum uncertainty corresponds to a splitting of timelines.--Srleffler (talk) 03:42, 16 June 2012 (UTC)

It's interesting that John Wyndham wrote ""every instant an atom of time splits" in The Seeds of Time before 1956 (I remember reading it before I'd ever heard of quantum mechanics), and the "Many Worlds" interpretation was published in 1957, but I assume Wyndham had read some earlier papers. The concept is a fairly obvious one, I suppose, and goes back thousands of years as a philosophical concept. Dbfirs 18:23, 15 June 2012 (UTC)

I don't think you understand my point exactly, Jayron. There is no such thing as a you that is separate from your body or the physical things which comprise it. (That's a notion left over from religion. What your body does is what your body does.) One of the faculties you and other higher animals have is volition--the ability to choose between different perceived paths of action. We're not talking about its freedom yet, just that volition exists. Plants don't have that faculty, nor do rocks, nor do atoms. It's a higher level emergent property of certain living beings. Now, of course it depends on your physical make up. Whether you get out of or stay in bed and on what side depends on processes that percolate in your brain. They are physical and at certain levels they are guided by certain natural laws. Eventually you-which means your body-which means your cells--which means the atoms that make it up--will come to a decision. Whether the rules that govern the motions of those atoms are in principle newtonianly determined or random doesn't matter to the higher level fact that your body can come to decisions. What makes those decisions free is not a physical, but a moral distinction. Was it your body that chose to stay in bed, in which case you are acting of your will freely, our did you burn to death because you were tied to the bed, in which case it was not of your--your body's--free will. To say that you are not free because you are your body--which is what determinists do--is a category mistake. It's almost like saying you can't pilot an airplane because aluminum is heavier than air, just on a more subtle level. Free will is a perfectly valid and necessary concept in a moral, not a mechanical context. μηδείς (talk) 18:37, 15 June 2012 (UTC)

Sorry, the Reference desk is not meant for philosophical discussions. It is not a forum. --Martynas Patasius (talk) 19:41, 15 June 2012 (UTC)

In some recent experiments involving functional MRI it was demonstrated that given some arbitrary choice you can make, one can already tell by looking at the MRI what you are going to choose about ten seconds before you say that you've made up your mind. Then, if you assume some many words scenario (the MWI of QM or the infinite number of regions similar to our observable universe as predicted by inflation theory), and you assume free will, then it becomes even weirder. Because then the moment you make up your mind, you locate yourself in that sector of the multiverse where the people observing your brain have already seen what you have decided. Count Iblis (talk) 21:13, 15 June 2012 (UTC)

I have read of such studies and I don't think the timelag is quite ten seconds. I could ask you to spout a string of random numbers and there would not be a 10 second delay before you started doing so. The fact that we are not aware of what we have chosen or said until after we have chosen or said it is not particularly problematic. If we had to deliberate in conscious words about what we were going to say before we said something we would never get started because we would have to deliberate which words to use in our deliberations, and so on, leading to infinite regress. How any of this fits in with so-called multiple universe theory, which cannot even be coherently formulated, let alone tested is beyond me. μηδείς (talk) 21:32, 15 June 2012 (UTC)

Interesting question. Could you tell what random numbers a person is going to spout before you let him know you want him to do so?

I am not sure, however, whether "you" can't be separated from the physical actions of the atoms in some way. Is there a way to say, that many different rearrangements of the atoms have absolutely zero subjective effect, and others matter? Is there some way to present consciousness as some kind of digital data in an algorithm? Just as a 1 or a 0 in computing can be independent of the minor thermal fluctuations of the chip they're coded in, and when those fluctuations foul up the value, that's not a normal computing operation, but a deviation from the 'intended' operation of the software. Do people perceive the world as the actual atoms, or as that discrete digital data? Wnt (talk) 22:24, 15 June 2012 (UTC)

If I understand your question correctly, you might want to look at supervenience. That is the concept that an emergent state might not specifically depend on a uniques set of lower circumstances, but that unless the underlying circumstances differ there can be no difference in the emergent states. For example, something's being evil might not necessarily depend on any one specific chemical physical states of afiars, but that if two circumstances are fully and exactly the same physically one cannot be evil while the other is good. μηδείς (talk) 23:00, 15 June 2012 (UTC)

That article seems like it must be talking about something else. I'm not suggesting a situation where a "lone ammonia molecule" would make a difference. What I mean is that if our subjective mental experience is some kind of "software", then small variations in the "hardware" may not matter. A simple program written in assembly language doesn't "see" the difference of whether the clock chip is running at a different speed, or whether it's being emulated as a program on some more complex system. The program only sees the parameters that matter to it, and produces its conclusions the same way in every circumstance. Wnt (talk) 03:46, 16 June 2012 (UTC)

I understand your point. Things whose natures are primarily functional can, as long as they are arranged in the proper form, differ in substance. Hylomorphism]] A drinking cup can be made of glass or plastic. It's still a Beethoven symphony whether the cellist is a man or a woman, she wears slacks or a dress, she sits to the right or the left of the wind section. That points out the problem with reductive materialism. Complex forms have to be executed in some substance, but it is the form that is essential.

Let's say I want to remind my self to schedule a doctor's appointment tomorrow. I might write myself a note. I might tie a string around my finger. I might write "Dr." on the back of my left hand in magic marker or sepia or nail polish. I might turn the bottle for my morningtime medicine upside down. There are an infinite number of arbitrary signs I can set for myself. What physically would be determining me to call the doctor in the morning? Sure, my brain and all these other things are made of atoms. But what about the velocity, mass, temperature, molecular structure or so on of these items would explain or "determine" me to call the doctor?

If I don't leave any sign for myself (including maybe internally as a short term memory) I won't call the doctor. But you can't reduce my calling the doctor to whether the string was cotton or wool. Nevertheless you have to admit that had there been no change in my environment I would not have been reminded to call the doctor. This is supervenience, when there cannot be a difference in a set of affairs of one type if there is not a difference in a set of affairs of another type. It is a way of preserving causation without falling into reductive determinism. In morality there cannot be a difference in guilt if there is no difference in intention, action ad result. There cannot be a difference in flavor unless there is a difference in ingredients, preparation and presentation. Note that the relation is not necessarily reversible. A change in preparation (shaken, not stirred) may have no effect on flavor. A change in action (I stabbed him with my right hand, not my left) may have no effect on guilt.

For a much better presentation of the matter by Rutger's Brian McLaughlin, see http://plato.stanford.edu/entries/supervenience/ μηδείς (talk) 16:59, 16 June 2012 (UTC)

Brownian motion of water molecule

When water is in its liquid phase, do its molecules diffuse around in Brownian motion or do they stay more or less in the same place? 65.92.7.168 (talk) 14:24, 15 June 2012 (UTC)

In still water they do both, though Brownian motion usually means the observable movement of particles much larger than one molecule. DriveByWire (talk) 14:32, 15 June 2012 (UTC)

It can't be both - the molecules must be either moving or not moving. The answer to the OP's question is Yes - the molecules do so move. However DriveByWire is correct in stating that term Brownian refers to observable particles suspended in the fluid. The correct term for the movement of molecules driven by thermal energy is random thermal motion, sometimes refered to as random molecular mobility, or just molecular mobility. Still water is only still in so far as convection currents and currents due to external forces are not present. Diffusion (the tendency for a molecular species in solution to even out its concentration) is another thing again, driven by random thermal motion. Ratbone120.145.14.192 (talk) 15:16, 15 June 2012 (UTC)

Perfect, thank you. 65.92.7.168 (talk) 01:20, 16 June 2012 (UTC)

I recommend that you read Diffusion. Plasmic Physics (talk) 02:04, 16 June 2012 (UTC)

Sidewalks that generate energy with our stepping?

Do we have an article about such sidewalks? Also, where are the prototypes already being tested?

Moreover, how far away is it from being practically installed in every major city? (For example, how much does an energy-generating sidewalk cost as opposed to an ordinary sidewalk, per average-sidewalk-sized tile?) Thanks. --70.179.170.114 (talk) 18:03, 15 June 2012 (UTC)

Stepping Razor Lyrics mp3 Bus stop (talk) 18:12, 15 June 2012 (UTC)

Look at the use of piezoelectric devices in the Energy harvesting#Piezoelectric energy harvesting article. (what does lyrics has to do with this at all??) Electron9 (talk) 18:29, 15 June 2012 (UTC)

(edit conflict)They are "hard work" to walk on (try walking in soft sand), so people would avoid them if they were designed to generate a large amount of energy, and if they are designed to be easy to walk on then they don't generate much energy. There are much better ways to get "free energy", so my personal opinion is that they will always remain an inefficient novelty. The Tokyo ticket gate system seems to generate a tenth of a watt! Dbfirs 18:34, 15 June 2012 (UTC)

The pesky rule of conservation of energy. The first physical law breaker criminal has not yet shown up ;-) Electron9 (talk) 18:38, 15 June 2012 (UTC)

Piano stairs are an entertaining variation on this idea. HiLo48 (talk) 07:51, 16 June 2012 (UTC)

That's a delightful idea HiLo48, but unsuited for areas with heavy pedestrian traffic. The viability of any scheme for extracting energy from human muscle activity depends on how much people enjoy the activity. Physical activity that we don't enjoy is called "work". An example to avoid is the fate of a Galley slave, unless you happen to enjoy being encourged by a whip. Another is the erstwhile prison Treadmill that had no purpose other than punishing its victim by wasting (as heat, see Mechanical equivalent of heat)) his effort, a situation that Oscar Wilde would profoundly lament in 1897. So-called energy-generating sidewalks would actually be energy-extracting devices, likely to be perceived as treadmills, and would need an extraordinary infrastructure (overseers with electric batons for encouraging pedestrians to step faster?). However during the 1973 oil crisis and resulting panicky search for alternatives an idea arose that human sexual activity could be tapped as a renewable source of energy. A scientific calculation from objective data on average copulation frequency and duration, typical genital dimensions, viscous drag and thrusting force suggested that significant power might be collected this way and volunteers for experiments in doing so would not be hard to find. DriveByWire (talk) 16:09, 16 June 2012 (UTC)

Microbiological terms

hello,

I am currently translating a German article, but I have troubles to translate the following terms:

• Kinetozysten (kinetocystae maybe?)
• Extrusom

Regards.--GoP_T^C_N 18:43, 15 June 2012 (UTC)

kinetocysts and extrusome. ---Sluzzelin talk 20:04, 15 June 2012 (UTC)

Thanks.--GoP_T^C_N 08:50, 16 June 2012 (UTC)

Human facial hair growth stimulation

Is there any reliable way to stimulate the growth of facial hair on humans?--201.244.29.54 (talk) 19:38, 15 June 2012 (UTC)

Some heart medicine does this. Electron9 (talk) 19:39, 15 June 2012 (UTC)

Testosterone should work, although how effective it is would depend on the body's prior natural level. SkyMachine ⁽⁺⁺⁾ 20:51, 15 June 2012 (UTC)

For some reason shaving seems to have this effect. It seems to come back faster and thicker each time. StuRat (talk) 02:32, 16 June 2012 (UTC)

Shaving increases hair growth is a popular misconception. manya (talk) 07:11, 16 June 2012 (UTC)

This and other hairgrowth-related myths on Snopes. --NorwegianBlue ^talk 08:35, 16 June 2012 (UTC)

They seem to have some questionable logic there. For example, they say that if it worked, those going bald would try it. Well, obviously it would only work on those capable of growing hair, just like cloud seeding to produce rain isn't going to work when the air is dry and cloudless. They also state that cutting the end of a dead piece of hair can't possibly affect the follicle, but the intact hair must cause stresses on the follicle, and it's not unreasonable to suspect that the follicle is able to use this info to alter the growth patterns, just as muscle growth varies with stresses on the muscle. StuRat (talk) 19:09, 16 June 2012 (UTC)

Hairdressers have told me that they were taught during their classroom training that hair growth is not affected by cutting - but I've never really believed it. But it would be hard to prove, as hair growth is affected by climate, hormones, what you eat, lots of things. Even though I am a male past retirement age, I let my hair grow to shoulder length. I used to need to get it cut more often, but now I get it cut short once at the start of summer and once at the end of summer. So, my hair grows faster during summer. It seems to me that if you keep your hair short, your scalp will be cool. If you let your hair grow long, it will insulate your scalp and it will be warmer (it sure feels cool when I get it cut) and a warmer scalp can presumbly grow hair faster.

The snopes article is not referenced and thus thus is not a scientific reference. I'm very suspicious about their claim that hats make no difference. My father's generation wore hats everywhere - it was the fashion then. Many men went bald from their 30's onwards - my father was just about totally bald at 40. I am decades past 40 now and I only have some temple thinning. Like all of my generation, I've never worn a hat, and most of us have reasonable hair. But we have better food too and better general health. However, at least here in Australia, men now in their 30's have been taught at school that they MUST wear a hat outside to avoid skin cancer. And I see that some of them are going bald. So, the moral in the story about encouraging facial hair? Keep your chin warm without a cover, somehow! Wickwack124.178.37.221 (talk) 14:25, 16 June 2012 (UTC)

Um, the snopes article is very referenced. Scroll to the bottom. It's certainly more scientific than your sample set of two (you and your father). I'm 26 and I can tell you I'm well on my way to joining the "bald at 40" crowd". There's probably a good reason why there aren't as many balding men as there used to be, and the idea that it's "hats" is absurd. -RunningOnBrains^(talk) 16:34, 16 June 2012 (UTC)

Those references are mostly just newspaper accounts, likely even more opinions. I'd like to see some scientific studies with thousands of people in them, please. StuRat (talk) 19:14, 16 June 2012 (UTC)

Exactly. Worthless. Wickwack58.170.165.180 (talk) 03:16, 17 June 2012 (UTC)

Is anyone so unlucky as to not get decent beard till 25 and start balding at 24? Sagittarian Milky Way (talk) 18:56, 16 June 2012 (UTC)

To look at me now, you'd think I was born with a beard. But I didn't manage to grow it properly till I was almost 30. All my previous attempts were pathetic failures. By the time I was finally successful, my vision and hearing had started to show signs of wear. There was no balding, though, not at that stage. That came later. -- ♬ Jack of Oz ♬ ^{[your turn]} 12:40, 17 June 2012 (UTC)

Couldn't at least the hearing be because of too much loud music? And I thought 40 was when vision declines. Maybe you're actually farsighted but didn't notice till the lens couldn't accomodate anymore? Sagittarian Milky Way (talk) 17:59, 18 June 2012 (UTC)

Some people researched this long back. manya (talk) 07:31, 19 June 2012 (UTC)

Looks like a good study, except that a data set from only 5 test subjects isn't enough. StuRat (talk) 07:49, 19 June 2012 (UTC)