Wikipedia:Reference desk/Archives/Science/2015 April 11

= April 11 =

Frog eyes
Why do (most) tree frogs have horizontally slit eyes? Wouldn't vertical slits be an advantage when you're jumping or when you're catching a fly with your tongue to be able to accurately gauge the distance? This confirms that it's indeed the EYE-riss, but that doesn't give more help. &mdash; Sebastian 01:31, 11 April 2015 (UTC)


 * I love the toes on that 2nd one. It looks like it would use them to suck all the salt out of your body and leave you for dead: . :-) StuRat (talk) 01:45, 11 April 2015 (UTC)
 * How do you know it doesn't? ←Baseball Bugs What's up, Doc? carrots→ 02:04, 11 April 2015 (UTC)
 * The Man Trap μηδείς (talk) 04:06, 11 April 2015 (UTC)


 * If the frog is on the surface of water, would vertical slits potentially result in confusing imagery when seeing both above and below the water line? ←Baseball Bugs What's up, Doc? carrots→ 02:06, 11 April 2015 (UTC)


 * No one seems to be sure. There is some discussion of this in our pupil article. Also see this abstract on The Functional Advantage of Slit Pupils.--Shantavira|feed me 06:20, 11 April 2015 (UTC)


 * Thank you, that was very helpful. The jov article's wording "better image quality for contours perpendicular to the pupil’s long axis" is something I implicitly took for granted in the above; it's good that they're making it explicit.


 * I hadn't thought of the pupil article. That contained at some point what seems like a good answer, written by DrChrissy: "Horizontal slit pupils are more effective in the vertical plane and allow better detection and recognition of obstacles or predators as they move into sight at speed." It got subsequently changed by someone who apparently misunderstood DrChrissy's wording, so I now reworded it. It contains admittedly some original research, but the situation seems pretty obvious to me. But I'm not married to my wording; I won't fuss if someone deletes it. &mdash; Sebastian 07:40, 11 April 2015 (UTC)
 * Hi Sebastian. Just a friendly note.  Your discussion about specific changes should probably go on the article Talk page (and maybe copied here - I don't know, I am new to this pasge).  I like your edit, but you should try really hard to find a source for it - I suspect it's half-life will not be long otherwise! All the best.__DrChrissy (talk) 11:18, 11 April 2015 (UTC)

How is the opposite of the cardiomegaly called?
When the heart is enlarged is called cardiomegaly, but what is the opposite of this case called? (when the heart is reduced). Thanks 149.78.253.71 (talk) 01:47, 11 April 2015 (UTC)


 * Well, microcephaly means an abnormally small skull. I'm not sure why the "micro" is a prefix instead of a suffix, or how it would be applied to "cardio". StuRat (talk) 01:52, 11 April 2015 (UTC)
 * Grinchocardio. ←Baseball Bugs What's up, Doc? carrots→ 02:03, 11 April 2015 (UTC)


 * That makes me grin: . StuRat (talk) 02:20, 11 April 2015 (UTC)


 * The opposite of cardiomegaly is a normal heart. Microcardia is a totally different condition.  It's like asking what is the opposite of a six-fingered hand, and answering a four-fingered hand.
 * I think you mean "cardiomicroly" or some such. Micromegaly means "smallbigly" and nonsensically doesn't answer the question.  Cardio should be in there somewhere.  And the OP's question makes sense, even if it is ultimately unanswerable because the condition doesn't actually exist.  There's nothing hypothetically wrong with supposing that a condition of heart shrinkage is possible.  -- Jayron 32 04:13, 11 April 2015 (UTC)
 * Thanks, just a typo (fixed) ; low blood sugar, new meds, pink elephants, maybe orange, or livid. μηδείς (talk) 04:58, 11 April 2015 (UTC)


 * GIven that at least some cardiomegaly is the result of left ventricular hypertrophy, there's a sense in which one might consider hypoplastic left heart syndrome its opposite... "Microcardia" is an abnormally small heart, but despite there being a word for it, is like a unicorn in not being spotted or referred to often. - Nunh-huh 05:00, 11 April 2015 (UTC)
 * The point is, the opposite of disease, is not having that disease. It's not some other condition. μηδείς (talk) 05:12, 11 April 2015 (UTC)
 * According what I know, the opposite of large is just small. Anyway, the main question is how small heart called in medical terminology (as a large heart is called cardiomegaly)149.78.253.71 (talk) 09:08, 11 April 2015 (UTC)
 * You are confusing logical contraries with contradictories. The opposite of white is not black; it is "not white".  One isn't cured of high blood sugar by low blood sugar. Normal blood sugar is not high.  But it's also not low.  See square of opposites. μηδείς (talk) 18:47, 11 April 2015 (UTC)
 * It would be more constructive to answer the intended question than to complain that the poster's English usage is different from yours. --65.94.49.82 (talk)
 * It would be more constructive for you to find out the answer (if any) rather than attacking other editors. ←Baseball Bugs What's up, Doc? carrots→ 09:54, 12 April 2015 (UTC)
 * Never mind the IP, Bugs, he's from Toronto. μηδείς (talk) 17:37, 12 April 2015 (UTC)
 * Seriously, guys, it was pretty obvious what the original poster meant. Most people would say that the opposite of a giant is a dwarf, that the opposite of hyperthermia is hypothermia, that the opposite of old is young. (And, for that matter, that the opposite of white is black) --Steve Summit (talk) 21:32, 12 April 2015 (UTC)
 * Seriously, guy, I'f he'd meant what the term for having a small heart was he'd've asked that, not led us on a merry goose chase. His question is like asking what's the opposite of a caddilac, the answer to which is obviously a tea rose. μηδείς (talk) 23:52, 12 April 2015 (UTC)
 * The OP seems to have been clear enough. In the OP's very first post, they specified "when the heart is reduced" [//en.wikipedia.org/w/index.php?title=Wikipedia:Reference_desk/Science&diff=prev&oldid=655912033]. I'm all for nitpicking when it serves a purpose, but in this case, I'm with Steve Summit. The opposite of hyperglycemia is hypoglycemia (edit: in fact our gyperglycemia article even calls hypoglycemia the opposite disorder), but neither of these are something you want (although both can be a problem for diabetics using insulin or some other medications). Edit: Note sure how cure came in to above, as the OP never said anything about curing anything. Oh and your example is not that similar to the OP's actual question. A better one would be someone asking what's the opposite of a luxury car, and specifying they mean a cheap no frills car. The best answer to the OP in that case would probably be an Economy car. It wouldn't be a normal car, that's for sure. It may be in some cases, possibly including this one, the answer is there's no real opposite, but that's still a better answer than saying the opposite is a normal whatever. Nil Einne (talk) 13:28, 13 April 2015 (UTC) Edits at 15:51, 13 April 2015 (UTC)
 * One thing that's not clear from the cardiomegaly article (unless I missed it) is whether this is a condition one is born with or if it develops over time. If the latter, the only thing that could be opposite is a disease causing the heart to shrink. Is there such a thing? And if not, why would there be a term for it? ←Baseball Bugs What's up, Doc? carrots→ 15:37, 13 April 2015 (UTC)
 * Well no one said there is definitely a term for it. In fact me and Jayron32 already said there may not be a term. In that case, the best answer is there is no term because the condition doesn't really exist (or whatever). It's not however saying that the opposite is a normal heart, which is clearly not what the OP was referring to. Note that perhaps a key point is that the OP asked about a medical condition that describes a specific physical effect. So asking what's the opposite, even if it turns out one doesn't exist, is a perfectly resonable question. The hypothermia and hypoglycemia examples would be similar cases, ironically Medeis first introduced the latter. If the OP had asked "what's the opposite of chickenpox", then yes perhaps the Cadillac example and Medeis's complaints would make sense. But not only did the OP not do they, they clarified at the very beginning they meant a condition where the heart is reduced. So even if people do want to nitpick over what opposite means, the OP's question is still clear enough. Nil Einne (talk) 16:04, 13 April 2015 (UTC)

Injecting a substance into the veins with the tongue.
I was wondering if there are any studies on any indigenous peoples or intravenous drug users that inject substances into the veins by biting than using their mouth and tongue as a sort of injection needle. Are some substances best delivered at the temperature of the human body? Bullets and Bracelets (talk) 04:55, 11 April 2015 (UTC)
 * Would be difficult to effectively administer drugs that way. Blood pressure is always higher than air pressure, so merely opening a vein with something like the teeth then applying drugs topically is an unreliable way to deliver the drugs the blood stream.  Intravenous needles rely on using a syringe to apply higher pressures to ensure the drug is delivered to the blood stream efficiently.  If blood is rushing out of a punctured vessel, then positive pressure prevents the drug from entering the body.  At best you'd get the drug into the blood via simple diffusion, which is such an inefficient process for this purpose it doesn't sound like it would be a useful way to do things.  All that being said, I wouldn't preclude individual anecdotes of people trying the method you describe, and even being successful (for an arbitrary definition of success), however there's no reason to suppose that it is a widely successful method, or statistically significant.  -- Jayron 32 05:04, 11 April 2015 (UTC)


 * No. If the person didn't bleed out from the ruptured blood vessel, he'd die from sepsis. Please stop asking absurd questions prefaced by I was wondering if there are any studies, such as "Are there any studies as to what happens if you extract an embryo and inject it into someones blood stream?"  You'll end up being blocked for disruption. μηδείς (talk) 05:11, 11 April 2015 (UTC)
 * Alternatively, go to Google Scholar, type your question into the search bar (much as you have done here) and if nothing relevant appears, the answer is probably "NO". Alansplodge (talk) 14:18, 11 April 2015 (UTC)
 * "Truly I tell you, I have not found anyone in Israel with such great faith." Wnt (talk) 20:23, 11 April 2015 (UTC)
 * Hebrews 13:8 KJV Alansplodge (talk) 20:26, 11 April 2015 (UTC)


 * William S. Burroughs described an ad hoc method involving a pin and an eye dropper, where the hole would first be made and external pressure used. So I don't see any obvious reason why this would necessarily fail, though opening the vein with teeth is sure hell a stretch.  (but tooth sharpening, hey you never know in biology, or anthropology for that matter)  Sepsis from introduced bacteria is of course possible, but primitive people survive a lot of abuse (in part because they tend to die so young...)  But the ancients often found ways to do things topically; for instance, if you go back and look at Dioscorides you'll see that opium was a topically administered drug much of the time.  So I don't think trying to get foreign substances into a vein would have been high on their to do list. Wnt (talk) 18:57, 11 April 2015 (UTC)


 * Burroughs also killed his wife. The problem is that any opening made in a blood vessel by biting is going to be ragged, and not stop bleeding without emergency action.  Also, the germs present in the mouth will cause nasty infections, requiring strong antibiotic treatment.  And there wont be any downstream flow of blood to carry the drug into the system, just a lot of it spurting about until the victim is treated or dies. μηδείς (talk) 20:57, 11 April 2015 (UTC)

Spectroscopy of molecules and atoms
Hi there,

Few questions:

1st: if atoms absorb only the exact photons that contain the exact amount of energy to leap the energy levels of the atoms, doesn't it mean that the possibility of absorption should be negligible? I mean, if 2 atoms have different energy levels, the likelihood that the photons that are emitted from one atom to another will be in the exact amount of energy is nothing. Is it? And even if you are able to emit all the wavelength that atoms can absorb, still, the length of the line that should be at the Spectroscopy should be invisible (Because its width will be nano-metric). And yet, we do see it with our naked eye.

2nd: Why in molecular Spectroscopy the absorption isn't binary? I mean, molecules can absorb some of the photons of a given wavelength, in contrast to atoms for example.Exx8 (talk) 08:48, 11 April 2015 (UTC)
 * our eyes are actually pretty sensitive, even to narrow line width absorptions. In addition, there Ade many factors that broaden those line widths, such as Doppler effect and motion of atoms making them "experience" a different wavelength, or broadening from atomic collisions (this broadening can be enough to turn gas discharge lamps from line sources into continuous sources). Molecular spectroscopy is subject to similar line broadening effects, with so!e additional ones, such as solvent effects. --OuroborosCobra (talk) 10:43, 11 April 2015 (UTC)


 * As OuroborosCobra points out, the atoms will be in different states and then you need to take into account the doppler effect, but that doesn't solve the problem that you raised, as each atom in its own rest frame will have precisely defined energy levels.


 * The problem is resolved by considering that the precise energy levels only arise when you ignore the coupling of the atoms to the electromagnetic field. In that hypothetical case, electrons in excited states would never make a transition to the ground state and emit radiation, but they would have precisely defined energies. What happens in reality is that these excited states are unstable due to the coupling to the electromagnetic field. Electrons in such states then do not have precisely defined energies (only so-called stationary states that do not evolve in time can have precisely defined energies, this is related to the time-energy uncertainty relation, you can also compare this to the fact that the frequency of a signal is only well defined if it is exactly periodic for an an infinite duration). This means that atoms can both emit and absorb photons with energies that differ from the differences in the energies of the energy levels. The probability density for such a process depends on the energy difference between the energy of the photon and the energy difference between the energy levels between which the transition takes place. The longer the lifetime of an excited state the more precisely defined the energy level is which then leads to a narrower peaked probability distribution for the photon energy. Count Iblis (talk) 16:17, 11 April 2015 (UTC)


 * One thing also hinted at, but not explicitly stated, is the sort of "cross talk" between atoms in condensed states (liquid and solid). The sort of distinct emission spectrum one finds where energy levels of all atoms in a sample are identical and strictly quantized into a limited number of allowable transition states only really occurs in difuse gases where the distance between the atoms is sufficient so they don't interact with each other.  Once you get a large bunch of atoms in condensed states, so they are all in contact, the energy states all "pile up", and you no longer are able to see distinct energy levels in experimental results; instead excited atoms now emit a continuum of energy rather than distinct emission spectrum.  This manifests itself in some different ways, such as the sea of electrons model of metallic bonding, or more universally, in the continuous spectrum of blackbody radiation.  While it would be true that any one atoms electron energy levels would be quantized even in condensed matter, taken in the bulk, these energy states overlap sufficiently to create a continuum of emissions/absorbtion of photons.  -- Jayron 32 03:38, 12 April 2015 (UTC)

Space: digital or analog?
Given a surface, can you place an object at any point that you want? Or would space be a kind of chessboard, when you can put the piece at any square, but not between two? Intuitively, it makes sense to believe that the first scenario is the case, but how can something like this be tested? At some time, by really small distances, we won't be to measure the space coordinates anymore, since we might have reached the maximum precision of our measuring devices. — Preceding unsigned comment added by 83.50.111.54 (talk • contribs)


 * Maybe someone has addressed this, but I think your question is really about space being discrete or continuous. Bubba73 You talkin' to me? 06:37, 13 April 2015 (UTC)
 * It's an open question that gets attention in the popular press. Look for the word granularity in our article quantum gravity. μηδείς (talk) 19:40, 11 April 2015 (UTC) In the future, please sign your posts by adding four ~ at the end. μηδείς (talk) 19:40, 11 April 2015 (UTC)


 * The question is asking about an aspect of quantum theory. If space is "a kind of chessboard", then the term for this would be that position is quantized. --65.94.49.82 (talk) 03:09, 12 April 2015 (UTC)


 * There are occasionally attempt to establish a "quantization of space"; I've seen some pseudoscientific discussion that hold both the Fine-structure constant and Planck length represent some fundamental quantization of space. I'm not convinced either is really that.  -- Jayron 32 03:31, 12 April 2015 (UTC)


 * My very limited understanding is that quantization comes from the Schroedinger equation - if you look at the first formula, it has that infamous ei hbar. That indicates that it's a differential equation with a solution with this exponential form.  I feel like there should be tools for making quantum mechanics far more intuitive than it is -- for example, if you take a rubber band and wrap it around your finger, you know that the number of times it goes around is going to be quantized; I bet there's some way you can write that with an intimidating ei form too, when all you're really saying is that a loop can't go partway around.  Anyway, the point is, whenever something is quantized, it's quantized in terms of Planck's constant, which is to say, the units of angular momentum.  Either it's an actual angular momentum of some sort, or it's a linear momentum times a distance (e.g. the wavelength of a photon).  So to see space quantized, we'd need to take our meters and multiply them by kilograms and by meters and divide by seconds somehow, in order to get the same units.  And if those figures differ for different things, the quantization in space should be different. Wnt (talk) 15:54, 12 April 2015 (UTC)


 * If space had a discrete lattice structure, like a crystal, then it would be anisotropic (diagonal motion would be different from orthogonal motion), and we haven't seen any sign of that in the cosmic microwave background, for example. If the units of space were arranged randomly (like a glass instead of a crystal), you wouldn't have that problem, but it would still break Lorentz invariance, which has been tested to surprising precision. This blog post claims "Extensions of the standard model that explicitly break Lorentz-invariance are very strongly constrained already, to 9 orders of magnitude above the Planck mass", though I'm not sure exactly what that implies for a discrete-space theory. There are probably ways to evade these bounds, but the simplest forms of discrete space are testable and I think they have been ruled out. -- BenRG (talk) 19:27, 12 April 2015 (UTC)
 * It could be quantized but coordinates are polar instead of cartesian. Relativity would imply any coordinates would always be relative to the object in question, so there need not be a global "grid". Ariel. (talk) 05:54, 13 April 2015 (UTC)
 * Incidentally, the chessboard does work pretty well in 1+1 dimensions (Feynman checkerboard). -- BenRG (talk) 19:30, 12 April 2015 (UTC)


 * One thing that is far, far beyond my understanding is the holographic principle. This holds that the "real" space we live in may be a sort of 2D cosmological horizon, rather than the 3D universe.  Since I don't know what the actual "values" of this 2D space are, I don't pretend to know whether they might be quantized or not. Wnt (talk) 19:52, 12 April 2015 (UTC)

selective mutism
Is selective mutism a recognized disability in the United States of America? Can one get disability payments for it? How do they weed out people faking it for free welfare money? Meridianvase (talk) 20:19, 11 April 2015 (UTC)


 * That's a combined medical and legal question. Contact a specialist on administrative law if you have a specific question. We can't answer a hypothetical one. μηδείς (talk) 21:52, 11 April 2015 (UTC)


 * Nay, this is a general question about United States policy. Searching for "Americans with Disabilities Act" and "selective mutism" turns up documents like  at selectivemutism.org.  I have not really looked into this much since bureaucratology isn't all that enjoyable, but I'm sure better answers can be given. Wnt (talk) 10:56, 12 April 2015 (UTC)


 * If a general question it's far too wide. In the specific case one needs doctors and lawyers to plead one's case for disability insurance, and how malingerers are diagnosed is a medical question.  Any meaningful answer for a specific question will require referring a person to legal and medical connsel. μηδείς (talk) 17:33, 12 April 2015 (UTC)