Wikipedia:Reference desk/Archives/Science/2012 December 21

= December 21 =

Ozone resupply
Is it feasible to fix or mitigate ozone depletion by dispersing artificially produced ozone?--93.174.25.12 (talk) 09:44, 21 December 2012 (UTC)
 * Yes and no. Clearly we can (and do) produce ozone.  That "metallic" smell you get when a cheap electric motor is running is ozone produced by electrical arcing.  But there are two problems with using this to mitigate the depletion of earth's ozone layer:
 * Ozone is only a good thing at very high altitudes (20 to 30km). Down here at sea level, it's a nasty pollutant.  So it's no use just setting up an ozone factory down here on the surface of the planet.  The gas would have to either be transported up there - or made up there in some kind of flying factory.  Both are exceedingly difficult things to do.
 * Producing ozone requires energy - and at the scales required to match the ozone that's naturally produced up there, we'd need an ungodly amount of energy. Right now, the odds are good that we do vastly more damage to the atmosphere from CO2 produced as a by-product of all of that energy usage.
 * SteveBaker (talk) 14:50, 21 December 2012 (UTC)


 * No, ozone is constantly being simultaneously created and destroyed in the stratosphere creating an stable equilibrium. Any added ozone would quickly be destroyed returning to the same equilibrium point. Ozone depletion is caused by the presence of some pollutants in the stratosphere which change the chemistry and shift the equilibrium towards a smaller amount of ozone. Dauto (talk) 14:57, 21 December 2012 (UTC)
 * So continuously pump in more and more ozone to keep it away from equilibrium. Whoop whoop pull up Bitching Betty 23:52, 21 December 2012 (UTC)
 * Well it's really more accurate to simply say that the pollutants (or rather their eventually chemically-unbound constituents) simply act to break down the reactive O3. The construct of a stable equilibrium state is an artificial one in this context and confuses the issue a bit. In any event, more to the point, there really isn't much need to produce ozone for this purpose; since the implementation of more significant controls of CFCs, ozone depletion has stabilized and even begun to be reversed in the most potentially ecological hazardous regions.  As noted above, there are other pollutants which are more significance issues at present.  Snow (talk) 07:56, 22 December 2012 (UTC)

Eight compartments in the rectus abdominis - which comprise the six pack?
So I'm not entirely sure whether it's rows 1-3 or rows 2-4 of the rectus abdominis that count as the six pack. By that I mean is the pair of somewhat angled compartments at the top of the muscle considered part of the six pack (or does it have some other colloquial name?) or is the pair of long compartments at the bottom of the muscle - below the navel - the bottom of the six pack (if no then does it have some other colloquial name?)?

http://robertsontrainingsystems.com/wp-content/uploads/2012/04/rectus-abdominis.jpg 184.152.17.125 (talk) 19:20, 21 December 2012 (UTC)


 * Looks like it's the top row, to me: . The bottom row tends not to be as visible. StuRat (talk) 04:17, 22 December 2012 (UTC)


 * Well, given that "six-pack" is a colloquial term and not a clinically anatomical one, it really has no absolute definition of which superficial features of the abdomen belong to it. That being said, in a person with well-defined-enough musculature, the outline of all of segments of rectus abdominis would be obvious, though which would be more prominent would, of course, vary by individual.  I don't know that people are really used to defining the "six" of the six-pack so precisely so much as using the expression idiomatically to refer to the whole of the mid-abdomen in a fit person, but I suspect if you asked people to make a call, they would mostly select rows 1-3 as the main constituents. Snow (talk) 08:07, 22 December 2012 (UTC)

Wireless energy and magnetic field
So, I was watching this video documenting wireless energy and how it would use magnetic fields to get the energy from one object to another. In it described some concerns with safety (e.g. cancers), and someone briefly described how we've been bathing in a magnetic field for thousands of years anyway, so there would be no real issue.

Though, two questions come to mind: would the magnetism from the wireless energy "outputs" be much higher than the Earth's? And second, why not just harness the magnetic field that we've been living in? Thanks! 174.93.61.139 (talk) 21:13, 21 December 2012 (UTC)


 * If you look at Orders of magnitude (magnetic field), you'll see that the earth's magnetic field is incredibly weak. (25 to 65 micro-tesla). By comparison, a small refrigerator magnet is about 200 times more powerful and a small neodymium magnet (such as you find in many modern products) could be around 100,000 times stronger.  So while we're pretty sure that the earth's magnetic field is "safe" - it's by no means obvious that much higher magnetic fields would not have health risks. SteveBaker (talk) 21:44, 21 December 2012 (UTC)


 * A steady magnetic field does not transmit energy. It has energy, but the energy just sits there.  So there is really nothing to "harness" from the Earth's magnetic field.
 * To transmit energy, what you need is a changing magnetic (and electric) field; that is, you need electromagnetic radiation. Such radiation has known, and probably some unknown, health effects, all of which vary widely depending on frequency/wavelength, but which are in general quite distinct from (and likely to be more serious than) any dangers from a static magnetic field (of the same average intensity as the changing one, say). --Trovatore (talk) 00:23, 22 December 2012 (UTC)


 * As for known health risks, those with metal implants must avoid strong magnetic fields, while extremely powerful magnetic fields can interfere with anyone's blood flow by affecting the iron in hemoglobin. StuRat (talk) 04:11, 22 December 2012 (UTC)


 * You wanna pop up a cite for that last statement? Ferromagnetism as I understand it is a bulk property of iron; it isn't usually seen in iron compounds (except maybe magnetite), where the iron atoms are dispersed from one another.  (I don't doubt that sufficiently powerful magnetic fields are dangerous, but I'm skeptical that the mechanism you propose is a particularly important one.) --Trovatore (talk) 06:08, 22 December 2012 (UTC)


 * Perhaps StuRat believes in Magnet therapy? The Science ref-desk is no place to spread fringe theories as if they had a scientific basis. DMacks (talk) 06:21, 22 December 2012 (UTC)


 * No, I certainly do not. While Magnet_therapy states that blood is weakly paramagnetic, the magnets used in "magnetic therapy" are nowhere near the strength needed to have any effect, and, even if they were, how would interfering with the normal flow of blood be helpful ? StuRat (talk) 06:25, 22 December 2012 (UTC)


 * Some relevant articles: Electromagnetic radiation and health, Wireless electronic devices and health, Mobile phone radiation and health. As far as I understand, for common household devices (mobile phones, wifi routers,...) there are many studies, but no generally accepted view, also due to the fact that people are exposed only for a couple of years, making the discovery of long-term effects difficult. As the situation is not clear, personally I'd minimize exposure, by switching of wireless devices when not needed, not sleeping near wireless sources, etc. bamse (talk) 08:52, 22 December 2012 (UTC)


 * There's an awfull lot of rot published about the effects of electromagnetic radiation, and cell phone emission in particular. The simple fact is this:  for any medical/physiological effect at all, at least one of two things must be satisfied:  a) the field strength is so intense that heating of body parts occurs above that which the bloodstream (acting as a heat conductor) can cope with.  This requires close proximity to quite high power radio transmitters well and truely beyond what a cellphone can put out. And the output of wifi routers and other local area wireless devices is even more minute. The stray radiation from tube-type TV sets is considerably greater and nobody worried about them, not should they.  b) the radiation is of sufficiently high frequency to be ionising radiation, eg X-rays.  Cell phone and wireless device radiation is too low in frequency to be ionising.  If neither of these two conditions are satisfied, then chemical bonds cannot be broken, and if chemical bonds are not broken then there cannot be any effect on the body.  End of story.  The trouble lies in how research grants are granted, and how editors select articles for publication.  If yoiu are a researcher, and ask for a grant to show that everything is hunky dory and nobody should worry, a grant committee, who probaly don't really understand it anyway, will not give you a grant.  But if you write out an application stating that a possible hazard needs to be investigated, you may get a grant.  And if you beaver away spending teh grant money and finally conclude that while you could not definitely establish cause and effect, there should be more research done, well, you might get more grant money.  And editors want to sell journals, so even in a professional journal, a bit of sensationalism helps.  Ratbone 124.182.16.117 (talk) 10:33, 22 December 2012 (UTC)


 * OK, first of all, field strength per se doesn't heat anything. A static field just sits there and transmits no power; that was the first point I made in the first response to the question.  Nevertheless, a sufficiently strong static field can indeed have effects on body functioning (things with dipole moments line up with the field; at some point that's going to affect something).


 * None of that is very applicable to cell phones, but it does indicate a problem with the line of reasoning that starts there are only two mechanisms for such and such.... Just because you haven't thought of a mechanism doesn't mean there isn't one.  I personally am not very worried about cell phones, but sufficiently rigorous epidemiological evidence would change my mind, whether or not I understood the mechanism. --Trovatore (talk) 21:43, 22 December 2012 (UTC)


 * Re static (steady) fields - yest they are irrelevant to this discussion - because you cannot have a "static" electromagnetic wave. You can have steady magnetic fields and steady electric fields, but to get an electromagetic wave, you must have time-varying fields.  Your statement that just because I haven't thought of a method doesn't mean that there isn't one looks ok in logic.  However, the requirement for either ionising radiation or sufficient intensity for heating is well established in science.  Beliveing that there may be some unknown 3rd method waiting to be discovered is much like believing that there my be a way of teleporting Star Trek style just waithing to be discovered.  It would be contrary to known scientific facts.  Ratbone 124.182.144.218 (talk) 01:24, 23 December 2012 (UTC)


 * The original question appeared to be about static fields. The questioner seemed to think they could be used for power, which of course they can't, but they were part of the question so they're not irrelevant.


 * Yes, but I was correcting the misconception posted by Bamse, involving radio emissions from cellphones, wireless routers and the like. Ratbone 124.182.144.218 (talk) 02:07, 23 December 2012 (UTC)


 * The rest of your statement is wrong. There are known effects of static magnetic fields, and they do not heat anything nor break any bonds.  Even if there were not any known ones, philosophically your tack is just plain wrong.  It is perfectly good science to look for an effect even when no mechanism is proposed. --Trovatore (talk) 01:29, 23 December 2012 (UTC)


 * No, its only good science to look for effects when there is at least a plausible theory, that cannot be rejected by known facts, that suggests that looking will be worthwhile. Otherwise time would be wasted.  One might as well run tests to look for effective telepathy.  That was a reasonable thing to do at one time, but not now that the electromagnetic sprectrum is understood.  Can you nominate a known effects of radio emission of living animals that does not involve breaking chemical bonds?  I think not - simply because any effect MUST involve chemical bonds - we are after all, made up of atoms combined together - we are a complex chemistry set.  Can you even cite a plausible theory for an effect?  Ratbone 124.182.144.218 (talk) 02:07, 23 December 2012 (UTC)


 * You have a cramped and restrictive view of science, one that is in my personal opinion very very wrong indeed. It is in fact good science to look for telepathy, and it has nothing to do with whether the electromagnetic spectrum is understood.  It so happens that well-designed experiments don't tend to find it, but that doesn't mean it wasn't good science to do them in the first place.
 * So no, I don't have to cite a plausible mechanism in order to look. If you find the effect, then you look for the mechanism.
 * HOWEVER, all that aside, static magnetic fields (which, recall, is what we were originally talking about) have documented effects on living organisms, without breaking any bonds. --Trovatore (talk) 02:44, 23 December 2012 (UTC)


 * There have been some studies that show the area around the ear where the cell phone is held gets a bit warmer. However, I don't see any need to resort to EMF explanations.  The phone simply acts as a thermal insulator and reflects heat back onto the ear which otherwise would be radiated away.  StuRat (talk) 19:12, 22 December 2012 (UTC)


 * Carefull, Stu. Somebody might think that warming the ears is itself bad Some of the warming will be due to absorbing radio frequency energy as the blood flow to the ears and nearby scalp is not great, so heat is not conducted away very well.  This does not apply to the brain as brain blood flow is quite prodigious.  However, nobody has reported any problems wearing earmuffs and full helmets and nobody wants to investigate them.  And we have other dangly bits that in the caveman days probably remained pretty cold but now sit within our clothes at close to body temperature.  Appart from possibly the lower sperm count in modern man (which has not been explained), no problems have been reported.  Ratbone 124.182.144.218 (talk) 02:45, 23 December 2012 (UTC)


 * This is exactly my point. Studies showing warming on the side of the head near the cell phone might incorrectly portray this as a "sign of dangerous radiation", when it's really just the result of having something warm next to your head. StuRat (talk) 07:54, 23 December 2012 (UTC)


 * Apart from heating and ionization, could the radiation affect electrical signals in neurons/the brain? bamse (talk) 20:24, 22 December 2012 (UTC)


 * The short answer is essentially no. The signalling between and within neurons is electrochemical.  This means that the operation of the brain and nervous system can be interfered with by electric fields - as in electric shocks.  The function can be affected without altering the structure.  However, it has been well established for 100 years or more that the functional sensitivity to electric fields is inversely proportional to frequency.  At the frequency of the power mains (50Hz or 60Hz depending onm country) the sensitivity is very marked - currents as little as a few microamps within the brain will produce conscious effects.  AT 440 Hz (A above middle C) the sensitivity is reduced by a factor of about 100x.  At 20,000 Hz (the upper limit of human hearing), sensitivity to electric current is practically gone completely.  The frequencies used by cellphones and routers are well and truely beyond these frequencies.  Technicians who work in radio broadcast transmitters (which use frequncies well below that of cellphones and wifi routers) get taught in their training, and sometimes learn the hard way, that coming into electrical contact, or experincing high field strengths with high frequency energy cannot be felt other than the normal pain felt from the resulting burns.  Ratbone 124.182.144.218 (talk) 02:21, 23 December 2012 (UTC)

Regarding the Stu's suggestion that a strong enough magnet could affect hemoglobin, as may also be aware, anything made out of atoms can be moved through direct diamagnetic levitation. The magnet has to be really strong though, and is not something that would fit on your wrist. Someguy1221 (talk) 11:16, 22 December 2012 (UTC)

Could the hand have a more ideal anatomy?
Ignoring any sentimental feelings we might have for the current configuration, or it feeling unnatural if you were suddenly given it (if you were born with 4 fingers and 2 thumbs, those hands you can control like second nature and the stock one would feel wrong) What could we do to better serve 21st century first world humans, more than hunter-gatherers? How about more fingers? Longer ones? Thinner ones? Extra joints? Of course extra length means the palm has to be longer to close them/make fists. More fingers probably means thinner and therefore weaker and easier to break. And forget opposable everything, there's no room for enough muscles. Really, I want longer thumb, though. (Added bonus: if we have 12 fingers, we get to use the superior base-12) Sagittarian Milky Way (talk) 21:45, 21 December 2012 (UTC)


 * The problem is that we humans modify our environment to suit our bodies - and on a longer timescale, evolution has modified our bodies to suit our environment. If our hands were larger, our cellphones would have bigger touch-screens.  The tools we use like screwdrivers are optimized to produce the maximum amount of torque for the hands we have.  Everything we do is built on a scale where we can interact with it.  So I suspect that most changes that you could imagine would be worse than what we have.  Sure, you could get more dexterity at the cost of less strength - or vice-versa - you could imagine hands that were more able to cup liquids or hands with a hard pad to allow us to use them as hammers.  But for every improvement you could come up with, there would be some kind of downside - because we're adapted to our environment - and vice-versa.  SteveBaker (talk) 21:57, 21 December 2012 (UTC)


 * Clearly, some of these things might not have realistic evolutionary paths. And you can't seperate cause and effect completely, but if intelligent designers had adapted us for this technological level instead of cave-man, our chimp-men ancestors might've had a somewhat harder life but we'd have an easier one and our technology would be suited to that (different game console controllers and screwdrivers maybe?) I don't know about the hammer pad though, rocks are everywhere. And even hand bone can get injured from punching a forehead hard enough, much less nails. But screwdrivers are not optimized to produce the maximum amount of torque for the hands we have. Assuming enough room, that would be something like this or that: Kreuzschl%C3%BCssel.jpg. Sagittarian Milky Way (talk) 22:39, 21 December 2012 (UTC)


 * I've thought having a second thumb in place of the pinky might improve dexterity. StuRat (talk) 04:06, 22 December 2012 (UTC)


 * When working inside PC cases and around car engines I've often wanted a longer thumb, and sometimes finger joints that bend both ways. HiLo48 (talk) 04:11, 22 December 2012 (UTC)

This new study suggests ours hands evolved as weapons, at least in part. Zoonoses (talk) 06:21, 22 December 2012 (UTC)


 * So I can't have longer thumbs just because they might stick out too far when you punch on instinct (i.e. without setting) and get hurt? Typical human. Sagittarian Milky Way (talk) 00:45, 24 December 2012 (UTC)

I suspect quite a few pianists would nominate being able to stretch further. Double sharp (talk) 13:55, 24 December 2012 (UTC)

If we started all over again, and ignoring that humans like to use the number of fingers they have, which number base is best to use?
12? 16? 20? If we go too high (like the Babylonians' base-60) there are too many symbols and practical scale numbers of the current era which aren't outrageously long in the first place (US national debt, 7 billion people) don't get much shorter. Lets say we don't wan't to just have base 26 (or 25, 24) by appending a mark to each letter. There are enough umalauts and diacritic marks in the world already. Sagittarian Milky Way (talk) 21:59, 21 December 2012 (UTC)


 * My opinion, first of all, is that base 12 is overrated. Sure, you can more easily divide by three.  How often is that a big issue?  It's not that hard in base ten.  And in base 12, you can't divide as easily by five.
 * Too small a base and numbers become unwieldy; too large a base, and you have to memorize big addition and multiplication tables. Other than that I don't think it makes that much difference.  Base 8 or 16 would have some minor advantages for the man–computer interface. --Trovatore (talk) 22:16, 21 December 2012 (UTC)
 * I guess a base 16 multiplication table is a bit large. But clearly, that we feel the compulsion to make base-10 multiplication tables go to 12 and 112 pound "hundreweights" and that Dunbar's number is 150 shows that there is an unmet need for larger two-digit numbers. Now onwards to make the 12-fingered human! Sagittarian Milky Way (talk) 01:13, 24 December 2012 (UTC)


 * The Babylonians used a base that could more accurately be described as mixed 6 and 10 so it didn't require all that many symbols. Dmcq (talk) 01:38, 22 December 2012 (UTC)


 * From a computational standpoint, the ideal number base would have as many small factors as possible. Base 60, for example, is good: the prime factorization is 2*2*3*5, making division by 2, 3, 4, 5, 6, 10, 12, 15, 20, and 30 easy.  From a usability standpoint, the ideal number base would have as few symbols as possible.  Binary is ideal, with only two symbols.  The "perfect" number base is a balance between the two goals (base 10 is fairly lousy from a computation standpoint, since dividing by 5 (easy) is less common than dividing by 3 or 4 (both hard)). --Carnildo (talk) 01:47, 22 December 2012 (UTC)


 * That doesn't seem right, unless "usability standpoint" is from the point of view of a computer. In human terms, binary is horrible to use. 86.171.174.84 (talk) 22:49, 22 December 2012 (UTC)


 * Also, in the earliest stages, there weren't distinct numbers, but rather a series of repeated objects. So, in a base-10 system, for example, 9 dots followed by a space, followed by 6 dots, followed by a space, followed by 2 dots would represent the number 962.  In such a system, it's best to use a small base, limited by how many dots most people can recognize instantly without having to count them.  Always placing the dots in the same pattern, as on dominoes, allows for a somewhat larger number. StuRat (talk) 04:04, 22 December 2012 (UTC)


 * Could you provide a cite for that, StuRat? I've seen that system before, but only as a latter day method of displaying the results of an abacus or similar instrument. Such a system would seem hinged on the idea of breaking numbers into "ones", "tens", "hundreds", and so on, which (I thought) was dependent on using an existing decimal system and its use of zero as a placeholder. Matt Deres (talk) 02:19, 23 December 2012 (UTC)


 * See Maya numerals (and note that I was only using powers of 10 in my example for simplicity, while the Maya used base 20). StuRat (talk) 06:20, 23 December 2012 (UTC)


 * That's very interesting; thanks for the link. Matt Deres (talk) 14:47, 24 December 2012 (UTC)


 * You're welcome. StuRat (talk) 05:30, 26 December 2012 (UTC)


 * Dividing by 4? That's not hard in decimal. Multiply by 0.25. All your base. - ¡Ouch! (hurt me / more pain) 18:04, 22 December 2012 (UTC)

Base 200560490130. Count Iblis (talk) 15:01, 23 December 2012 (UTC)


 * Accept these multicolored bitmaps as my proposed symbols for 200560490128200560490130 and 200560490129200560490130 (magnified 0.1 times) > :


 * Double sharp (talk) 13:52, 26 December 2012 (UTC)


 * Heh. My illustrations of uniform tilings of the hyperbolic plane (see my Commons page) are 2520 pixels across, because that's lcm(1,2,3,4,5,6,7,8,9,10). —Tamfang (talk) 17:56, 27 June 2013 (UTC)


 * Is that because those are the decimal digits? ;-P Why not 27720?
 * Personally, I would say base 60 is the best. Double sharp (talk) 05:25, 20 November 2013 (UTC)


 * Not lcm(1,2,3,4,5,6,7,8,9,10,11,12) = 27720 because I didn't want to wait 121 times as long for my computer to finish the damned things. —Tamfang (talk) 05:47, 20 November 2013 (UTC)
 * Diminishing returns of higher primes, eh? ;-) Double sharp (talk) 08:28, 20 November 2013 (UTC)


 * Well, slower returns. (It took me over a week to fill that table. Afterward, I noticed that my code used complex arithmetic where it could have used real arithmetic. Oh well.) —Tamfang (talk) 18:15, 20 November 2013 (UTC)