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April 25

pH Determination

What caused compounds to have lower pH values than other compounds? — Preceding unsigned comment added by Bibibubsy06 (talk • contribs) 08:24, 25 April 2012 (UTC)

Well usually they are more acidic. For the common type of acids they will produce more H⁺ ions. This may be because the H+ has less force and energy attaching it to the rest of the acid. It may be because the rest of the acid molecule has lots of atoms that attract electrons, eg trifluoroacetic acid has a lower pH than acetic acid. Graeme Bartlett (talk) 11:13, 25 April 2012 (UTC)

pH is an property of a solution--generally speaking the greater concentration of "whatever dissolved chemical", the lower the pH if an acid or the higher if a base. The "acidity or basicity" of a compound is termed pKa. So Graeme's TFA is more acidic than acetic acid--the chemical has a lower pKa. But a dilute solution TFA might still be "only very slightly lowered" (for example, pH 6.8) because it is dilute even though the acid itself is a intrinsically stronger. DMacks (talk) 21:13, 25 April 2012 (UTC)

Chemical kinetics - why no 2nd order reaction data?

Considering a quantity of contained pure hydrogen gas, it will come to an equilibrium monotomic (H) and diatomic (H₂) mixture. Logically, it seems to me that the following 2nd order reactions will occur:-

H + H → H₂.....................(1)

H + H₂ → H + H + H.........(2) normally written as H₂ + M → H + H + M, [M = H]

H₂ + H₂ → H + H + H₂......(3) normally written as H₂ + M → H + H + M, [M = H₂]

and the following 3rd order reactions will occur:-

H + H + H → H₂ + H.........(4) normally written as H + H + M → H₂ + M, [M = H]

H + H + H₂ → H₂ + H₂......(5) normally written as H + H + M → H₂ + M, [M = H₂]

Since it seems that nobody has discovered H₃, thre is no need for any more reactions such as H + H₂ → H₃. Upon a search, I found reaction rate data (eg Arrhenius quation constants) for Reactions (2) through (5), for example in Journal of Physical Chemistry Reference Data Vol 12 1983 Page 531-590. I have found data in other publications as well. However, I cannot find reaction rate data for Reaction (1). Is there some reason why this reaction can be ignored? Given that a quantity of gas is represented by particles of size <<< the mean distance between them, the probability of two molecules coliding in a given length of time must be considerably greater than three molecules colliding. What have I not realised? Some databases (eg NIST Chemical Kinetics database) list Reaction (1) in indexing, but when you follow the trail, you'll find that they actually meant H + H + M → H₂ + M, and didn't bother to write the M, which suggests perhaps that either they were slack, or that users ought to know there should be an M, or both. Ratbone120.145.51.113 (talk) 08:44, 25 April 2012 (UTC)

What you are asking is basically why can't two hydrogen atoms collide and make H₂. This has been asked before, see http://en.wikipedia.org/wiki/Wikipedia:Reference_desk/Archives/Science/2011_February_24#Question_on_collision_between_hydrogen_atoms_.28momentum_.2F_energy_question.29. Essentially, the answers there seemed to be that the sum of kinetic energy and bond energy must be conserved, and this means that if H₂ is formed the conditions exist to immediately split it again. To form H2, a third collision partner is required to carry off some kinetic energy so that the bond energy lost has somewhere to go. The transfered bond energy can then gradually transfer to the bulk of the gas by subsequent (non-raective) collisions. I have to say I'm not confortable with this explanation - why can't the newly formed H₂ molecule race off with increased velocity, to be dissipated in subsequent collisions? See also http://en.wikipedia.org/wiki/Wikipedia:Reference_desk/Archives/Science/2012_January_17#Order_of_chemical_reaction. Keit120.145.175.169 (talk) 03:39, 26 April 2012 (UTC)

To answer your last question, it has to do with conservation of momentum. The momentum of the hydrogen molecule formed would have to be equal to the sum of the momenta of the hydrogen atoms that formed it; there's no way for it to suddenly pick up speed. TenOfAllTrades(talk) 04:30, 26 April 2012 (UTC)

I've wondered for a while: could the excess energy just be emitted electromagnetically? --Tardis (talk) 00:54, 27 April 2012 (UTC)

You are not the first to ask that. It was asked by BenRG in Refrence Desk on 24 Feb 2011, and nobody answered it. I don't know a direct answer either. However, any closed amount of hydrogen comes to an equlibribrium with the fraction of H and fraction of H₂ in a certain ratio depending on the temperature. The ratio can be calculated by using dissociation/recombination mathematics http://en.wikipedia.org/wiki/Dissociation_(chemistry) derived from first priciples. At equilibrium, the reactions H₂ + M → H + H + M, [M = H,H₂] sum to an equal rate to the sum of reactions H + H + M → H₂ + M, [M = H,H₂]. So any photons / electromagnetic energy emitted by H + H + M → H₂ + M must be immediately and totally absorbed by H₂ + M → H + H + M, since the system is stable and emits no photons. That does not seem likely. Nor do photons affect the equilibrium fractions, other than by simple heating. Keit124.182.22.228 (talk) 01:16, 27 April 2012 (UTC)

Inappropriate paint

Apparently an inappropriate paint was used on the cabinets above my stove, since the paint is peeling as a result of rising steam from cooking. When I repaint, what type of paint would be best to resist this effect ? StuRat (talk) 16:15, 25 April 2012 (UTC)

Hey, I can't believe you couldn't have done this. Richard Avery (talk) 16:59, 25 April 2012 (UTC)

I want paints which are steam resistant, not paints where the manufacturer claims they are. StuRat (talk) 18:06, 25 April 2012 (UTC)

I don't know about steam per se, but in terms of bathrooms and other areas where one expects moisture, a more important factor in preventing peeling is often the use of a good primer rather than the choice of paint itself. The primer creates a moisture barrier and improves adhesion to the surface, which helps resists peeling and cracking that could occur after frequent exposure to moisture. I assume that similar principles apply in the presence of steam. Did you use a good primer the first time? Dragons flight (talk) 18:24, 25 April 2012 (UTC)

It was already painted when I moved in. StuRat (talk) 18:38, 25 April 2012 (UTC)

Ita erat quando hic adveni. Heard that excuse many times before  ;-) --Aspro (talk) 19:10, 25 April 2012 (UTC)

Heus, modo itera omnia quae mihi nunc nuper narravisti, sed nunc Anglice? SpinningSpark 21:08, 25 April 2012 (UTC)

Well parried but not quite touché – “I only rented this cheap loco poco (little hovel) (or Poco Loco – a little crazy) because my daddy din'nt have job at the time and so threw me and my entourage out the house. Just look at the dump I've landed in.” Hardly the situation that Ovid would have found himself in -don'nt you think?--Aspro (talk) 17:56, 26 April 2012 (UTC)

If we are talking about a rental (or some low cost new construction), it isn't uncommon to see landlords doing cheap / quick painting that looks good for a bit but won't last. For example, a coat of the cheapest paint available with no priming and without cleaning up old layers. Often landlords aren't even required to maintain the look of a place. As long as there isn't a safety issue, the renter may be out of luck when the paint starts to peel. Dragons flight (talk) 19:53, 25 April 2012 (UTC)

Having been a tenant, and later a landlord, I can say that although you do occaisonally get bad tenants, and occaisonally there are skinflint landlords, the most common problem is ratbag managing agents in league with roque maintenance contractors. So if a tenant reports something needs some work, the managing agent calls his pet maintenance contractor, who does a shonky job (or even no job) for a cheap price, and the managing agent tells the owner/landlord that work needed to be done, and here's the (high price) cost. After a while, the tenants get pissed off due to the poor quality maintenance and having to make lots of complaints, and the owner thinks all the expense is due to a bad tennant. Good managing agents are worth their weight in gold. At the same time, as an owner you learn a lot if you have a beer with your tenants now and then. Wickwack58.167.243.91 (talk) 04:38, 26 April 2012 (UTC)

europa europa

Forgive me for my ignorance, but as far as I know, you cannot differentiate between an erect circumcised and uncircumcised penis. So, why did the protaganist(Jupp) in Europa Europa avoided sex with hot Leni.--122.161.40.115 (talk) 22:24, 25 April 2012 (UTC)

I expect you could if you looked closely enough. Also, don't forget the floppy-time, after. :-) StuRat (talk) 22:29, 25 April 2012 (UTC)

Humans can be highly emotional and irrational creatures. Bruce Hood performed a social experiment where he offered people money if they put on a sweater for 15 minutes that used to belong to a serial killer (not even really, but he said it was). More then half of the people asked wouldn't do it. Even if you can't tell the difference, there is a perceived "essence" to things which can emotionally repulse us, or attract us for that matter. In another experiment, children are asked if they mind if one of their toys is replaced with an identical copy. For the most part they don't mind, but if they have a favourite toy, they refuse to exchange it, even if the replacement is indistinguishable from the original. Vespine (talk) 22:58, 25 April 2012 (UTC)

(original poster here) how is this related to the original question? Or are you trying to imply that he didn't screw lina for psychological reasons rather than getting himself caught pants (and foreskin) down.--122.161.40.115 (talk) 16:48, 26 April 2012 (UTC)

I always wondered what Bruce Hood did after he retired from the NHL. There's an old saying in regard to objects from questionable sources: "You don't know where it's been!" Or in some cases, you do, and that's sufficiently repellant. However, it also might depend on how much money was offered. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:32, 25 April 2012 (UTC)

Of course, I think he was only offering $10 or $20. Vespine (talk) 01:21, 26 April 2012 (UTC)

Wearing John Gacey's sweater should be harmless, provided it was certifiably, thoroughly laundered first. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:28, 26 April 2012 (UTC)

Err, you can tell the difference. Google it up if you are really curious. --Mr.98 (talk) 01:24, 26 April 2012 (UTC)

Google says that it is not possible to know if an erect penis is a circumcised one or an uncircumcised one under normal circumstances. Obviously a medical practitioner in a lab will find out as one of the difference is that the skin gets cornified in the case of circumcised ones. However, a normal girl in a sexual intercourse cannot find that out.--122.161.40.115 (talk) 16:48, 26 April 2012 (UTC)

Are you using a funny version of Google? Because I'm not seeing the same thing [1] (not exactly a neutral source but it's far more useful then stuff like Yahoo answers), [2] (while it doesn't comment on the appearance much, it does not the movement of the foreskin which again could be something she would notice particularly when touching the penis), [3], [4] and [5] all suggest it's sometimes/often? possible to tell even when erect (although the later notes it's not always easy even when not flaccid). In fact you seem to be contradicting yourself, by saying a medical practitioner in a lab will be able to tell but there's no risk she will notice something seems wrong. Remember as I noted below, we aren't discussing her simply looking at him in a pornographical movie or seeing it when he flashed her ([6]) or knowing with a high degree of certainty but simply the risk of her getting suspicious enough during a real world interaction with him naked, that it may lead to his being identified as circumscised (perhaps partially from the medical examination) at a time and place (and by a person) where it was a very bad thing, and therefore questions to be asked about his heritage which could lead to his death. (Note also I presume he was circumcised sometime in the 1920s so any scarring may be more visible then with more modern medical techniques.) Nil Einne (talk) 21:42, 26 April 2012 (UTC)

In addition to what the other two first level indenting posters have said, bear in mind as our Foreskin, the degree of retraction during an erection (without manual retraction) varies so in some individuals it may be as easy as with an unerect penis. And of course even if the foreskin does retract by itself, it doesn't mean it can't be moved to partially or completely cover the Glans during an erection, in fact this is a common masturbation technique and the similar movement during sexual intercourse is cited as one reason by circumcision opponents for the alleged harm. Of course some men with phimosis can't retract the foreskin fully at any time. Nil Einne (talk) 15:40, 26 April 2012 (UTC)

What I am saying is that Jupp could have passed off as a normal case. Am I wrong? --122.161.40.115 (talk) 16:48, 26 April 2012 (UTC)

I don't see any reason to think there wasn't a big risk. At the very least, if she had any experience she may be suspicious from both the look and at the lack of any obvious ability of the foreskin to retract or move at all even if all she saw was his fully erect penis. And there's no reason think that's all she would have seen. Even given his age and the alleged 'hotness' of the female involved, there's no guarantee he would have been fully erect from the moment she first saw his penis to when she last saw it. Pressure can do strange things, the pressure of being at risk of being killed likely even more so. Some men may dig the 'banging the hot chick who wants to kill me' angle, others may be disgusted by it.

And despite what you may see in the movies, particularly those of the pornographical nature, it's unlikely that he can be sure he would be fully erect by the time his pants came off. He could try more foreplay while fully clothed but what's he to do if she starts to remove his pants before he's ready? For that matter what if she or he fumbles and takes too long and he's starting to lose his erection? And of course he'd want to quickly put his clothes back on once he's done the deed. If he's luckly she may just be insulted, if he's unlucky she may be suspicious. And the risk is only likely to increase the more times he does it.

If his only risk was being slapped or perhaps dumped, perhaps it would be an acceptable tradeoff. But all in all, speaking as a male, I'd gladly screw the screwing and not put myself at risk of being killed, and it hardly seems surprising if he would do likewise. (Of course there would likely be a risk him refusing to do it would lead to her spreading rumours that may lead to his identification. But on the whole, it would seem a lower risk. Notably, the risk of her doing so would likely increase if he refuses to do it again and she already had some minor suspicions from the first time.)

Nil Einne (talk) 21:19, 26 April 2012 (UTC)

Realised I forgot to consider something. Even if it were true he has little risk of being identified if he had sex (& to be clear, I still suggest if we consider it from a real life more realistic & messy sex POV, it's way to risky to have sex with someone if your circumcised and being identified as such by the person you're having sex with puts you at strong risk of being killed); it's quite doubtful that a teenage? boy in the 1940s would have any real idea that it were so. And definitely not something he'd want to ask people about. Nil Einne (talk) 03:17, 9 May 2012 (UTC)

Bicycle wheel spoke breakage load question

Hi. I have a pretty standard bicycle, with (AFAICS) standard steel spokes on the wheels. One broke the other day. How much force does this take? I would estimate, using the figure for carbon steel on Ultimate tensile strength of 500 MPa, and an area of $10^{-6}{\rm {m}}^{2}$ a breaking load of 500 Newtons, which doesn't seem very much. I would have estimated 5000 Newtons. Have I erred in my calculation, or is my expectation wrong? Robinh (talk) 23:26, 25 April 2012 (UTC)

110 pounds breaking force? Sounds about right. --Carnildo (talk) 01:01, 26 April 2012 (UTC)

Is tensile strength the right measure? You weren't stretching the spoke. Depending on how it broke, it was either due to compressing the spoke (so you want the compressive strength, which doesn't have any examples other than concrete, unfortunately) or it broke because it was pushed sideways, in which case I'm not sure what measure of strength is relevant. --Tango (talk) 01:46, 26 April 2012 (UTC)

Tensile strength is the right meassure. In any case, in metals, compressive strength is equal to tensile strength, in theory. But you almost never get to meassure compresive strength in metals because in compression they will bend. A bycicle spoke is such a long thin specimen that compressive strength is totally irrelevant. In my experience, broken spokes are a common occurance and occur due to travelling over severe bumps or misjudging a curb jump. This puts sudden compression in adjacent spokes, which merely bend, and sudden high tension in opposite spokes, which break. Wickwack58.170.143.160 (talk) 02:44, 26 April 2012 (UTC)

(OP) thanks guys. I'm relieved to discover that broken spokes are common. The spoke "popped" when I was cycling along, not going over a bump or anything. It just went sproing and then I noticed that the wheel had buckled (badly enough to exert the brakes every revolution). Is this normal too? Robinh (talk) 07:34, 26 April 2012 (UTC)

If a spoke (or more) breaks, then yes, it is normal for the wheel to be defromed.

As a temporary fix, you can adjust the length of the other spokes to get the shape of the wheel closer to normal. This takes a tool and a lot of practice. You must aim for the wheel to be planar so that the breaks can work, but the wheel will likely still have a bump, giving an uneven ride. (You must also remove the broken spoke from the wheel.) This is a temporary fix not only because of the uneven ride, but also because the rest of the spokes and the rim will now have to take more stress, and thus other spokes can break or the rim can get damaged.

As a permanent fix, you must replace the broken spoke with a new one, then adjust the spokes again. You can have this done in a bicycle service if you don't have enough practice. Obviously if the rim is very damaged, then you might have to buy a completely new wheel instead.

– b_jonas 09:32, 26 April 2012 (UTC)

Bicycle spokes nearly universally break not because of overloading, but because of metal fatigue due to the repeated loading and unloading of the spoke, with corresponding stress in particular at the knee of the spoke. Spokes in a well-build wheel rarely break, but if spoke tension is too low, the loading/unloading effect during rotation is more pronounced, and the spoke will break earlier. If the spoke tension is high enough, all spokes will remain under tension permanently, so the metal will not deform significantly. Except for high-end models, modern bicycle wheels are machine-build, and should be re-tensioned after a few hundred kilometers. Unfortunately, doing this is a job for an expert. But it is well worth the money. --Stephan Schulz (talk) 18:03, 26 April 2012 (UTC)

Thanks guys! I was using the tensile strength of the un-fatigued metal, whereas the spoke was presumably very fatigued when it broke.

Resolved

Robinh (talk) 21:49, 26 April 2012 (UTC)

April 26

what is dark matter

what is matter which has only gravitational activity ,not electromagnetic not thermodynamic and so on,does the light pass through such matter ?I have problem with thermodynamic properties of dark matter.Akbar mohammadzade--78.38.28.3 (talk) 04:10, 26 April 2012 (UTC)

No one really knows what dark matter is, although there are numerous hypotheses; see the Dark matter article. Red Act (talk) 04:18, 26 April 2012 (UTC)

It is an invention, to explain the break down of gravitational theory on the large scale of galaxies and the universe. Gravity does not seem to function as the current threories predicts it to, so instead of modifying existing theory, cosmologists have invented dark matter. That is dark matter's sole purpose. Plasmic Physics (talk) 05:49, 26 April 2012 (UTC)

What Plasmic said. It doesn't "exist" except on paper, and even there some have challenged the rationale behind it. Evanh2008 (talk) (contribs) 05:51, 26 April 2012 (UTC)

Well now saying it like that makes it sound like physicists are lazy. Truth is there have been dozens if not hundreds of proposed alternative explanations for the observed gravitational anomaly, but the only one that is completely consistent with observations is some "missing mass": dark matter. And until we come up with better observations or a better theory we'll just have to go on not knowing what exactly that dark matter is. I don't like it, but it is what it is. And don't even get me started on dark energy.-RunningOnBrains^(talk) 06:07, 26 April 2012 (UTC)

Ok then, what do you make of Einstein's self professed fudge: the gravitational constant, which now appears to be not so constant after all? Plasmic Physics (talk) 07:17, 26 April 2012 (UTC)

It's actually just a sign of how good his theory was. The GR equations popped out, they said "the universe is not static," Einstein said, "dang, that doesn't sound like what the astronomers are saying, does it?" and so he added the cosmological constant in there to make it match the observations. Later the astronomers figured out that they had been wrong and it was expanding, and if you remove the constant, GR works great as it ought to. So it's actually something in favor of GR, not against it. Einstein called it a "blunder" because he ought to have trusted his equations more and discovered something fundamental; instead he trusted the astronomers too much and fudged the equations. --Mr.98 (talk) 12:40, 26 April 2012 (UTC)

It is just as reasonable for a child to believe in the tooth fairy, because they can't explain why money magically appears when they leave a tooth under a pillow. Plasmic Physics (talk) 07:21, 26 April 2012 (UTC)

And your argument is just as bad as saying to that child, "You're wrong because your theory is silly." We've been waiting 80 years for someone to propose a theory of gravitation that doesn't require dark matter to explain galactic motion. Alternatives to the tooth fairy dark matter theory have been proposed but they all suck. You could certainly argue that the theory of dark matter also sucks since it never told us how to identify the invisible little buggers, but at least it didn't require a fundamental rewriting of well-tested physical laws. Someguy1221 (talk) 07:36, 26 April 2012 (UTC)

I wasn't saying that the theory is wrong, just that everyone of them tastes funny because they are all half-baked, they took their dark matter brownies out of the oven and served it too early. Plasmic Physics (talk) 07:44, 26 April 2012 (UTC)

Note that we now have fairly strong evidence for dark matter. MOND theories can, with some fudging, explain some features of galaxy rotation. But they are hard to apply to things like the Bullet Cluster, MACS J0025.4-1222, and Abell 520, where galaxy collisions have basically separated the interstellar gas (and hence most of the baryonic mass) from the stars, but the majority of the total mass of the galaxy has stayed with the stars. --Stephan Schulz (talk) 19:40, 26 April 2012 (UTC)

I would also note that the 'half-baked' part suggests a lack of understanding of how science and the scientific method works. You don't leave a theory in the oven (whatever that means) because it isn't cooked yet. Speaking in a very, very simplified manner, someone comes up with one or more hypothesis to explain some finding. (You don't generally wait until you have an extreme amount of evidence before publicly proposing something since it means both that someone may get there ahead of you, and that others can't consider your findings and attempt test them in various ways.) As evidence accumulates, other scientists come to accept your hypothesis/es as a valid scientific theory. If at some stage, evidence emerges which appears to contradict your theory you either refine it or (you or someone else) come/s up with a new one that better fits all the evidence. Scientific understanding is constantly changing, so it's difficult to say something is 'done' or fully baked, although obviously different theories can be at different stages of acceptance with different amounts of evidence in support of them. Nil Einne (talk) 20:55, 26 April 2012 (UTC)

Compare with Darwin's theory of evolution. Plasmic Physics (talk) 02:47, 27 April 2012 (UTC)

I guess what I'm getting at is: is the dark matter theory predicting observations, or are the observations predicting the theory? Plasmic Physics (talk) 02:54, 27 April 2012 (UTC)

Both, of course, as per the scientific method (observation->hpothesis->prediction->test). Darwin had finches and domestic animals, Einstein started with e.g. the Michelson–Morley experiment, Newton even had the benefit of Kepler's laws and his apple, and so on. Dark matter had a mismatch in galaxy rotation rate, and predicts things like the clusters I mentioned above. --Stephan Schulz (talk) 04:20, 27 April 2012 (UTC)

OK, I see. I then retract my critisism. Plasmic Physics (talk) 04:40, 27 April 2012 (UTC)

Returning to the original question, dark matter (hypothetically) does not interact with or "feel" the electromagnetic force, which is "carried" by photons - so, yes, light will pass right through it. It does not interact with the strong or weak forces either. The only one of the four fundamental forces that affects it is gravity. I don't think this means it has no thermodynamic properties - thermodynamics arises from statistical mechanics, which would still apply to dark matter. However, with only relatively weak gravitational interactions to distribute energy, it could take a very long time for a "cloud" of dark matter particlaes to reach thermodynamic equilibrium with itself or with ordinary matter. Gandalf61 (talk) 08:27, 26 April 2012 (UTC)

Dark matter can interact by the weak force. Neutrinos are dark matter (but there aren't enough neutrinos to account for all of it). Dark matter can even interact by the strong force—see SIMP. -- BenRG (talk) 05:30, 27 April 2012 (UTC)

Yes - my bad. Fixed above. Gandalf61 (talk) 08:27, 27 April 2012 (UTC)

thank all specially Gandalf61 . for using "electrodynamic of moving objects" we ought to know that the matter is made of hadrons ,or dark matter(for full discussion) .we need to have its properties , as its state , mass and center of mass ,internal and external reactions , radiating ,... the termodynamic relations in statistical physics strongly depends on matter properties and state ,gas liquid or solid ,and plasma mode .DARK MATTER is which one of such states ? — Preceding unsigned comment added by 78.38.28.3 (talk) 09:42, 26 April 2012 (UTC)

Since dark matter particles are not bound to one another by any electromagnetic forces, then dark matter must be a gas. On a small scale, where gravitational interactions are not significant, you could probably model it as a monatomic gas. On a larger scale I imagine you would use something like the virial theorem. Gandalf61 (talk) 09:49, 26 April 2012 (UTC)

Dark matter isn't in atomic form so it is not a gas, plasma, solid or plasma. Weakly interacting massive particles (a leading DM candidate) are more like slow fat neutrinos. SkyMachine ⁽⁺⁺⁾ 09:56, 26 April 2012 (UTC)

I don't think a gas has to be composed of atoms - see photon gas, Bose gas, electron gas. But my point was that dark matter can (on small scales) be modelled thermodynamically as an ideal gas, regardless of whether you think it is strictly a gas or not. Gandalf61 (talk) 10:34, 26 April 2012 (UTC)

It reminds me of the commercial for dawn dish soap where one drop of soap disperese a large amount of grease on the surface of the water. if you saw the grease moving away from that spot you would thing there was something pulling that grease in the direction you see it going. but actually it was the soap pushing it.165.212.189.187 (talk) 13:02, 26 April 2012 (UTC)

Something is pulling it - the surface tension of the water. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 19:13, 26 April 2012 (UTC)

There you go.165.212.189.187 (talk) 19:27, 26 April 2012 (UTC)

"There you go" I can't tell which side you're analogizing for. -RunningOnBrains^(talk) 20:47, 26 April 2012 (UTC)

well, you often use a "flat" universe analogy to understand it so there's another one.68.83.98.40 (talk) 01:34, 27 April 2012 (UTC)

The most favored theory is that dark matter (DM) is the lightest supersymmetric particle. There is indirect evidence for this, e.g. from the fact that such a particle would interact with matter via the Weak interaction. This then more or less fixes the dark matter density of the universe. The smaller the annihillation cross section of DM particles, the sooner after the Big Bang it would have decoupled, leading to freeze-out at a higher temperature and in turn to a higher present day DM density. The present day DM density is consistent with DM particles interacting via the Weak interaction.

Also, the annihilation cross section is related to cross section with ordinary matter partcles, via crossing symmetry. E.g., if you take a Feynman diagram for DM-anti-DM articles annihilating into a positron and an electron, and you rotate it 90 degrees, you get a Feynnman diagram for the scattering of a DM particle off an electron. Count Iblis (talk) 19:26, 26 April 2012 (UTC)

the source of planets' atmospheres

How had planets been able to contain surrounding atmospheres?Akbar mohammadzade — Preceding unsigned comment added by 78.38.28.3 (talk) 05:54, 26 April 2012 (UTC)

Gravity. Evanh2008 (talk) (contribs) 05:57, 26 April 2012 (UTC)

Also internally generated planetary magnetic fields prevent the solar wind from steadily stripping away the atmosphere. -RunningOnBrains^(talk) 06:12, 26 April 2012 (UTC)

You can also read the question on Europa's atmosphere found above. Plasmic Physics (talk) 07:09, 26 April 2012 (UTC)

Not really. ;) Evanh2008 (talk) (contribs) 07:39, 26 April 2012 (UTC)

"Not really"? Plasmic Physics (talk) 07:46, 26 April 2012 (UTC)

I think he was refering to the other Europa NSFW section above SkyMachine ⁽⁺⁺⁾ 07:58, 26 April 2012 (UTC)

Silly me, it's already been archieved. Plasmic Physics (talk) 08:07, 26 April 2012 (UTC)

The larger the mass of the planetary body, the easier it is for the planet to hold on to an atmosphere, thus gravitational attraction is the important factor here. Compare Jupiter with Mars or Earth for instance. Earth loses its lighter gases such as hydrogen and helium where Jupiter holds on to these gases. A cold temperature helps too, Pluto keeps its atmosphere because it keeps refreezing when it gets further out in its orbit. SkyMachine ⁽⁺⁺⁾ 07:48, 26 April 2012 (UTC)

for analyzing the combination of carbon dioxide for atmosphere of planet we can result one of this reasons :

  3- 1) The gas has been absorbed from flattened primordial disk
  3-  2) The gas has been absorbed from interstellar space
  3-  3) The gas has been created from volcanic activities (as there are several high   
                    mountains in planet)
  3- 4) Existence of  any growth process (for example process which increased oxygen 
                    on earth surface  for crust oxidation and its existence in our atmosphere  
  3- 5)Our scenario that the gas has been absorbed from solar wind (the solar wind   
                   carried particles are pulled to atmosphere , the light ones such
as hydrogen  and helium cannot  remain there for their velocity :    Vrms=√3kT/m 
(Boltzmann equation)

[[source : Analytical mechanics calculations for finding main reasons for opposite rotation of Venus Author: Akbar Mohammadzade)]] — Preceding unsigned comment added by 78.38.28.3 (talk) 09:50, 26 April 2012 (UTC)

Yes, that is true. Atmospheric gas come and leave, different types of gas leave more often than others. As gravity increases, they will leave less often, but come regularly. Statistically, they will never stop leaving.

Question for anyone: as solar wind travels long distances through space, does it cool down and radiate energy away as light, while slowing down enough to be captured by the outer planets? Plasmic Physics (talk) 10:15, 26 April 2012 (UTC)

It is not right to say that they cannot remain, it is not so black and white. You can say that statistically one molecule of hydrogen or helium is less likely to remain within the atmosphere for as long as a molecule of something heavier. Plasmic Physics (talk) 10:20, 26 April 2012 (UTC)

Plasmic Physics ! please see http://www.gsjournal.net/Science-Journals/Research%20Papers/View/4000 the solar wind particles generally remain in solar system and they are cooling by synchronious radiating . the archimedian spiral of particles movement model is shown in : [[http://www.gsjournal.net/Science-Journals/Research%20Papers/View/4029 ]] — Preceding unsigned comment added by 78.38.28.3 (talk) 10:30, 26 April 2012 (UTC)

. — Preceding unsigned comment added by 78.38.28.3 (talk) 10:26, 26 April 2012 (UTC)

I cannot, I have no access to your computer. Plasmic Physics (talk) 11:00, 26 April 2012 (UTC)

This link should work. Evanh2008 (talk) (contribs) 21:21, 26 April 2012 (UTC)

Akbar Mohammadzade your hypothesis has atmospheres growing over time as they accumulate gas from solar wind, how is this consistant with Mars having lost considerable atmospheric density since its volcanism, magnetic dynamo (and magnetic field) came to a halt? SkyMachine ⁽⁺⁺⁾ 21:47, 26 April 2012 (UTC)

If I may, I believe that at the pressure of the solar wind is too high at that distance from the Sun, so rather than bing absorbed, it blows away the preexisting atmosphere. For planets further out from the Sun, the solar wind pressure is low enough to be overcome by gravity. As an example: let a mug be called a planet, and a water tap be called the Sun, and the water be called the solar wind. Then open the tap to maximum, you'll notice that the high pressure of the water blows any water clear out of the mug. However, if you close the tap to a gentle flow, the water will fill the mug. Plasmic Physics (talk) 00:53, 27 April 2012 (UTC)

Electric Field & Electric Force

Whatis the difference between electric field and electric force ? — Preceding unsigned comment added by Temesgen Mengesha (talk • contribs) 07:07, 26 April 2012 (UTC)

One is a field one is a force experienced by an electrically charged object moving in that field. Plasmic Physics (talk) 07:09, 26 April 2012 (UTC)

What Plasmic said. An electric field is something that occupies a three dimensional space, but it does not do anything as long as no charged particles are within the field. In contrast, an electric force is something that acts, and is located on a particle. In an electric field E, a particle with charge q experiences a force in the direction of the field equal to q*E. - Lindert (talk) 08:14, 26 April 2012 (UTC)

Influence of electric field on chemical equilibrium

How is expressed in formulae the influence of the electric field on chemical equilibrium in cases where this influence occurs like the dissociation of hydrogen molecule and hydrogen atom ionization? (to name a few processes pertaining to gas phase ion chemistry and also electrolytes namely effects like Wien effect and Debye-Falkenhagen effect)--188.25.241.99 (talk) 15:59, 26 April 2012 (UTC)

You (simply) factor in the change in energy of the products and reactants due to the electric field and perform the usual maneouvers.

(note) In some cases the electric field will cause separation of chemical species - this is effectively the same as the field 'doing work' to the system - in these cases you also need to factor this in (eg if it affects the starting species). Clearly if the field is doing work in separating species then this affects the positional entropy of the reaction products - something to bear in mind... In extreme cases it can change the reaction or reaction mechanism or species..

First order effects of electric field are just that of the Electric potential energy of a charged particle in a field... The situation gets more complex as you try to be more accurate. (eg dipoles, polarisable molecules etc etc)Oranjblud (talk) 01:21, 27 April 2012 (UTC)

for how long duration of time the sun was T-tauri star

first solar system emberyo of star formed in our global cloud, was T-tauri mode of it , the question is the age of such star which changed to be modern sun?Akbar mohammadzade.

T Tauri star says they join the main sequence (which is the type of star the Sun currently is) after about 100 million years. --Tango (talk) 13:15, 26 April 2012 (UTC)

Blue glow when pulling apart a Band-Aid wrapper?

For a couple of nights, I've been putting a Band-Aid on my finger after turning off my lights for the night. I've noticed that when I pull the wrapper apart in a dark room, the wrapper glows electric blue where the adhesive that's sealing in the Band-Aid is separating. Why does it glow blue? - Purplewowies (talk) 17:19, 26 April 2012 (UTC)

Your description suggests triboluminescence. Dragons flight (talk) 17:27, 26 April 2012 (UTC)

The article for which mentions Band-Aid wrappers specifically. -- Finlay McWalterჷTalk 17:28, 26 April 2012 (UTC)

Here's an interesting article from Nature about producing X-rays with scotch tape using the same effect: Sticky tape generates X-rays. -RunningOnBrains^(talk) 21:01, 26 April 2012 (UTC)

Here is Nature's video version of the same article. Producing an X-ray image of a finger by unwinding sellotape is just extraordinary. SpinningSpark 00:27, 27 April 2012 (UTC)

There is a whole heap of videos on YouTube showing tribolumiescence in duct and scotch tapes.[7][8][9] SpinningSpark 00:42, 27 April 2012 (UTC)

The triboluminescence article says some kind of asymmetry might be needed, such as impurities, but does not say what that is. Do they mean polarity and if so any ideas on how would that happen with the tape? --Agentundertables (talk) 00:59, 27 April 2012 (UTC)

"...triboluminescent activity is usually assumed to be a consequence of crystal asymmetry, ie only piezoelectric (non-centrosymmetric) crystals may be triboluminescent since only such crystals can develop opposite charges on the opposing faces of a developing crack" from [10]. SpinningSpark 02:24, 27 April 2012 (UTC)

How do they make large, curved sheets of glass?

Actually, I'm not even sure how they get normal windshield to the exact shape, but my question is inspired by those staircases you see at some Apple stores. They have pieces of glass that are quite a few square meters in a perfect cylinder section. I understand how they get glass really flat, by floating it on melted metal, but how do they get those perfect curves? I'd imagine they would bend it while still hot, but how do they then support it without causing dents or irregularities? 196.210.179.55 (talk) 20:56, 26 April 2012 (UTC)Eon

• "How Do They Do It? How Do They Make Curved Glass?" video. Clarityfiend (talk) 21:23, 26 April 2012 (UTC)

An example of a manufacturing facility involving curved glass. Bus stop (talk) 22:28, 26 April 2012 (UTC)

Another video showing aspects of a process manufacturing curved glass. Bus stop (talk) 22:35, 26 April 2012 (UTC)

This explanation says that curved glass is a 'pane' to produce. Bus stop (talk) 16:39, 27 April 2012 (UTC)

Color change

Hello, is there any way to change the color of you're semen? I need to for an experiment Astro Philip (talk) 23:41, 26 April 2012 (UTC)

Add some food coloring to it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:16, 27 April 2012 (UTC)

Lol, I'm guessing they mean "before" it comes out. You know, like eat lots of vitamin C to change the color of your pee. Otherwise it's trivial. I've heard you can change the smell, but not heard you can change the color by anything you eat... Vespine (talk) 00:23, 27 April 2012 (UTC)

There are also documented ways to change the taste. Anyway, I'm not aware of any research into the color. What are you trying to do? Make it more white, more clear, or something really weird, like turning it blue? If that's the case, would you mind if your entire body turned blue as well? Someguy1221 (talk) 01:30, 27 April 2012 (UTC)

Diet has no direct effect on semen color. Any effective method will be impractical, expensive, or hazardous. Drugs such as finasteride are known to cause green semen, but this is due to infection. If you want reddish semen, you could induce a mild case of hematospermia by undergoing a transrectal biopsy of the prostate, a procedure which usually causes bloody semen as a side effect. If you desire a more exotic color, you might persuade a urologist to inject some food coloring directly into your seminal vesicles. That would be benign, but I bet you'd have a hard time finding a doctor willing to do it. LANTZY^TALK 19:04, 27 April 2012 (UTC)

Please note that hematospermia increases the already high propensity of seminal fluid to act as a vector of disease. AlexTiefling (talk) 21:51, 27 April 2012 (UTC)

At point does this wander into "medical advice" territory? ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:04, 27 April 2012 (UTC)

My thoughts exactly, bugs. I'm aware of a former graduate student at MIT who managed to turn his entire body (and all bodily fluids) blue by injecting himself with "something". I don't feel right saying what per WP:BEANS. Then again, if anyone reading this has a habit of giving himself intravenous injections of random chemicals because someone on the internet said it was safe, he's probably hopeless. Someguy1221 (talk) 03:13, 28 April 2012 (UTC)

I assume you're talking about methylene blue. Note however that the decolorization of methylene blue is a routine test for semen quality. [11] though there are aspersions cast on its accuracy, and in any case I'm finding it hard to find a straight answer about how long it takes. I suppose I'd have to see it to believe it. Methylene blue was administered widely to troops in the second World War, being convenient for the purpose as it is a moderately effective antidepressant, with the added excuse of being a moderately effective antimalarial drug... despite reading various ditties about how "Even at the loo, we see, we pee, navy blue" I didn't see anything about blue ejaculate.

My first thought was that you might put a fluorescent label on fructose, and as asinine as that sounds, there's actually a publication about such a thing! (PMID 17444608). But I have no idea if this substance would be absorbed and concentrated by the seminal vesicle, indeed, whether seminal vesicles even accept outside fructose that is un-fooled-around-with. Wnt (talk) 04:59, 28 April 2012 (UTC)

April 27

Mean motion orbital resonances discrete?

I mean, for instance, is the Pluto-Neptune resonance really 2:3, as opposed (say) to 2:2.999999621739? Or perhaps the answer is "They are as nearly discrete as anything in Nature is"?—PaulTanenbaum (talk) 00:52, 27 April 2012 (UTC)

I don't think that it is discrete like that, since the planets are continually continually changing their momentum. They are very slowly moving further out from the Sun, just like the Moon is moving further away from the Earth. I think that most recent measurements indicated that we're losing the Moon at a rate of 5 cm per 370 days. Plasmic Physics (talk) 01:34, 27 April 2012 (UTC)

The resonance is exactly 2:3 when averaged over a long period of time. Over the short term, perturbations from many sources (ranging from other planets to the solar wind) will change the ratio of the orbital periods, while gravitational effects between the two work to eliminate those perturbations. --Carnildo (talk) 01:59, 27 April 2012 (UTC)

Most orbital resonances aren't stable, which implies that in those cases, the ratio of the orbital periods is only ever roughly close to a ratio of integers. Even when the orbital resonances are stable, in the short term the ratio of the orbital periods will oscillate a bit around the equilibrium ratio. And in the long term, if for example it takes about 2n and 3n orbits for the apsidal precession of the orbiting bodies to precess all the way around the central body once, the ratio of the number of orbits of the two bodies during that time will actually be around (2n+1)/(3n+1) for some large n instead of 2/3 during that time period. However, the ratio of orbital periods in a stable orbital resonance will in the long term approach an average that's an exact ratio of integers if you're counting anomalistic periods instead of sidereal periods. Red Act (talk) 04:35, 27 April 2012 (UTC)

Monk's hood oil feeling

After seeing Monks Hood from the series Brother Cadfael by Ellis Peters, I wondered how it actually felt to have my skin massaged by monk's hood oil. Being seemingly interested in being a herbalist, at my young age, I was really wondering if anyone knows. — Preceding unsigned comment added by 68.56.22.80 (talk) 01:11, 27 April 2012 (UTC)

Have you see Aconitum#Traditional_and_Modern_Medicinal_uses

Molecular sieves

Is it possible to use molecular sieves to precisely refractionate individual hot-fractions of crude oil? Plasmic Physics (talk) 01:42, 27 April 2012 (UTC)

I can't find species "Aphenops cronei" that was mentioned by Dobzhansky

For a 40th anniversary review, I'm trying to fact check a comment Theodosius Dobzhansky made in 1973 about this beetle species, Aphenops cronei. He said it is found only in some limestone caves in southern France. Fact-checking this has been difficult since the Internet appears to have no description of this particular species. A beetle genera Aphaenops (also perhaps Aphoenops) exists, but a cronei species is not listed anywhere online. I've searched the Encyclopedia of Life, Google Books, and Wikispecies, along with the entire Web. All I can see implies that the web only contains Dobzhansky's mention of this species, so I cannot verify his claim. Any thoughts? Bob Enyart, Denver radio host at KGOV (talk) 04:32, 27 April 2012 (UTC)

I'm also finding no record of a sp. cronei, but this article, if you can get access to it, may be helpful—its abstract says that "other taxa are compared when necessary to eliminate the confusion accumulated by old records in the literature." Deor (talk) 11:39, 27 April 2012 (UTC)

Available also at Ingentaconnect if anyone has an account. SpinningSpark 14:19, 27 April 2012 (UTC)

Thank you! That link, and your search result matching mine, both are very helpful. This is my first visit to the Ref Desk. I appreciate you guys! Bob Enyart, Denver radio host at KGOV (talk) 18:04, 28 April 2012 (UTC)

Event horizon of universe

Our visible universe is roughly 26 billion ly's if the universe is infinite then there could be infinite matter/energy outside our visible universe. Could this be the explanation of dark matter/energy? Wouldn't the gravitational effects of infinite matter outside our event horizon affect us even though the light doesnt reach us?165.212.189.187 (talk) 14:12, 27 April 2012 (UTC)

No. Gravity travels at the same speed as light, so if its light hasn't reached us, then likely its gravity hasn't either (not necessarily true, but close.) Goodbye Galaxy (talk) 14:45, 27 April 2012 (UTC)

OK but if gravity of an object 20 bl ly away can affect us and gravity from another object 20 bl ly farther away from that can affect that then isnt the farther object vicariously affecting us too? please also clarify your statement in parentheses.165.212.189.187 (talk) 15:25, 27 April 2012 (UTC)

Well, an object 20 billion lightyears away has entirely negligible gravitational effects on us. The fact that the universe is expanding cannot be accounted for by the pull of hypothetical mass outside the edge of the observable horizon. The fact is that gravity makes things contract, not expand. As for the parenthetical statement, I was thinking of dark matter, which has gravitational effects but emits no light. Goodbye Galaxy (talk) 15:41, 27 April 2012 (UTC)

Yes ONE object probably does have negligible effect but infinite objects surely dont!165.212.189.187 (talk) 15:53, 27 April 2012 (UTC) When you say "hypothetical" mass youre automatically assuming that we are in the exact middle of the universe. Duh gravitation effects but emits no light kind of like my vicarious allusion.165.212.189.187 (talk) 15:51, 27 April 2012 (UTC)

Nope. It doesn't matter how much mass there is beyond the observable universe. Anything that's not within our observable universe CANNOT affect us (until it is within our observable universe, which may never happen, given the accelerated expansion of the universe), and we can't even see its effects on the most distant galaxies either, because light travels at the same speed. I probably should have made that more clear. - Goodbye Galaxy (talk) 16:26, 27 April 2012 (UTC)

You are ignorant to the fact that objects outside our observable universe are affecting objects inside our observable universe (at the far reaches).165.212.189.187 (talk) 16:38, 27 April 2012 (UTC) A affects B, B affects C, eg A affects C or B does not affect C?165.212.189.187 (talk) 16:40, 27 April 2012 (UTC)

You're ignoring the speed of light and gravity. If the sun were to magically vanish, we would both remain in orbit and see the sun shining for 8~ minutes until the light and gravity reach us at the same time. Likewise, if something is pulling on a distant galaxy, and we can measure it, then it is necessarily within our observable universe, otherwise we wouldn't see the effect. So because we can measure the effects of dark energy, it is necessarily within our observable universe. It cannot be outside it. See light cone. - Goodbye Galaxy (talk) 16:59, 27 April 2012 (UTC)

The objects we see are not only far away, but also far back in time since the light and gravity from them takes a long time to reach us. If something is far away from us, then the only things that can have affected it (up to the point at which we see it) must have been close to it. In very rough terms, if the universe is 13.7 billion years old, and we observe an object that is 13 billion years old, then only other objects within about 700 million light years could have impacted it up until the point at which it is currently affecting us. Transitivity doesn't allow you extend beyond the visible universe. (There are some caveats to this associated with inflationary epoch and the global geometry of the universe, but for the current discussion those are less important.) Dragons flight (talk) 17:05, 27 April 2012 (UTC)

(EC x 2) It's important to keep track of when one object has an effect on another object, because objects aren't affected by other objects instantaneously. How soon one object can affect another object is limited by the speed of light. It's also important to keep track of when one object is inside of another object's visible universe, because objects near the boundary of the visible universe wind up leaving the visible universe, due to the metric expansion of space. The boundary of the visible universe is defined by where and when the metric expansion of space has overtaken the speed of light. B may be currently being affected by what A was doing long ago, and C may be currently being affected by what B was doing long ago, but C will never be affected by what A was doing long ago indirectly via B, if what B is doing now will never affect C because B has left the future C's visible universe. Red Act (talk) 17:35, 27 April 2012 (UTC)

OK, but couldn't there still be a possibility of this happening with say a-z objects each within the 700 mi ly range in a long chain? — Preceding unsigned comment added by 165.212.189.187 (talk) 19:36, 27 April 2012 (UTC)

No. If a gravitational wave or burst of light from object a originating at time t can never have any effect on us directly due to the metric expansion of space expanding space faster than can be kept up with even by travelling at the speed of light, then that gravitational wave or burst of light isn't going to have any easier time affecting us by adding some extra links in the causal chain along the way to us. Causality, i.e. information, just can't travel faster than the speed of light; making intermediate stops along the way can only hurt. Red Act (talk) 22:28, 27 April 2012 (UTC)

I think your argument about transitive causality is reasonable and it's basically correct, except that you need to think fourth-dimensionally. If objects A and B are separated by 700 Mly, then A now is affected by B from 700 Myr ago and vice versa. You can continue this relationship transitively—(A now) and (B 700 Myr ago) are both affected by (C 1400 Myr ago), and so on—but as the times and distances get larger you have to take general relativity into account, and eventually (about 14 Gyr back) you reach the limit of current understanding of cosmology. What you can't do is construct a causal chain out to the edge of the present-day visible universe.

That said, we already know the distribution of dark matter and dark energy. It's the one thing that we do know about them. And they are distributed uniformly (at cosmological scales) throughout the visible universe, not concentrated at the edge. So your suggestion is a non-starter. -- BenRG (talk) 05:17, 28 April 2012 (UTC)

As I understand it, the question of whether the universe is open or closed is basically a question of whether it is within its own event horizon. Am I mistaken? Wnt (talk) 13:23, 28 April 2012 (UTC)

Unranked taxa

What does "unranked" mean in taxonomy, such as in wasabi or Tulipa gesneriana?--176.241.247.17 (talk) 14:28, 27 April 2012 (UTC)

It just means that the given group is not a taxonomic rank. For instance, the wasabi example indicates that "Angiosperm" is unranked. The reasoning and history behind this lack of rank is explained at Angiosperm#History_of_classification (probably in more detail than you want). Many unranked grouping were previously ranked, but lost that distinction due to later developments. We still use them though, because it is very handy to use "angiosperms" as a word for flowering plants. The fact that it isn't a ranked taxonomic term is only important if you happen to be a taxonomist, and/or researching plant systematics. SemanticMantis (talk) 14:38, 27 April 2012 (UTC)

The term is somewhat akin to a classification like Monkey. That is, there are some terms which have historical reasons for getting carried through common English, but which are not recognized by actual taxonomists as a valid classification, for various reasons. Taxonomists use the term monophyletic to describe a group that shares a single ancestor, and where all decendants of that group are decended from that single ancestor, in other words a complete branch of the "family tree". This is also called a clade. It is not certain that angiosperms are a true monophyletic grouping. It is certain that monkeys are not. --Jayron32 22:06, 27 April 2012 (UTC)

Suppose we have a Magic Mosquito Genocide Contraption

Flick a switch, and all blood-sucking mosquitoes on the planet are spontaneously killed. What effects would this have on the biosphere, and would it be of overall benefit or detriment to humanity? Goodbye Galaxy (talk) 14:49, 27 April 2012 (UTC)

You'd have a pretty drastic effect on pond ecosystems throughout any area where mosquitoes are endemic. Mosquito larvae happen to be important (sometimes the exclusive) food source for young fish in such ecosystems. Someguy1221 (talk) 15:01, 27 April 2012 (UTC)

I believe there are places where they were virtually wiped out, for a time, during health campaigns. I believe the building of the Panama Canal was one such case. It definitely seemed to benefit humanity. Any adverse effects on the biosphere didn't much make it up to humans. Considering that millions of people die each year from mosquito-borne illnesses, it's difficult to imagine how they could provide a bigger benefit. StuRat (talk) 21:56, 27 April 2012 (UTC)

Not exactly a scientific source, but Cracked claims that mosquitos are essential to the food chain: because they can carry large amounts blood, they are an invaluable source of protein for many species. This slightly more authoritative source agrees. -RunningOnBrains^(talk) 22:10, 27 April 2012 (UTC)

And according to Nature there are mixed opinions. Scientists agree that they are a vital part of the food chain, but some believe mosquitoes could easily be replaced by other (non-disease-spreading) species. -RunningOnBrains^(talk)

Decision-making - Can we actually make decisions?

Obviously there are some parts of human behavior which are uncontrollable, such as autonomic behavior. Is there a part of our behavior that we can control, and if so, what? This is important question to answer if we want to become competent decision makers - If we wish to figure out how to behave and live our lives, we must first find out what parts of our behavior, if any, we can actually control. Free will probably doesn't exist, but nonetheless Steven Pinker has pointed out that there is a useful distinction between controllable and uncontrollable behavior. Widener (talk) 16:17, 27 April 2012 (UTC)

Of course there are behaviors you can control. Unless you suffer from a disability like Tourette syndrome, you should be able to control what you say, for example. There are also other behaviors which are largely automatic, but which can also be controlled, to an extent, like blinking your eyes or breathing. StuRat (talk) 17:37, 27 April 2012 (UTC)

I believe that when you ask "Is there a part of our behavior that we can control", the word "we" hides an implicit dualism, and the most useful answer is to make the dualism explicit. Where you go from there depends on your attitude toward dualism. Looie496 (talk) 17:45, 27 April 2012 (UTC)

Or one could just accept that we're algorithms run on a machine (the brain). No pecisely specifed algorithm can have real free will (at most an illusion of free will. However, there are a huge number of algorithms that could represent you, given what you experience at some moment. Neural networks are involved in pattern recognition; the pattern that is recgnized contains far less information than the elements that form the pattern. A slightly different neural network could have led to the same pattern being recognized.

Then given the enormous amount of neurons in the brain, there must exist a huge number of different possible neural networks that are all slightly different, which would have led to the same subjective "you". If the fundamental nature of reality is purely mathematical, then all these algorithms really exist (and they all find themselves embeded in some physical world that looks identical to them). So, you should then identify yourself with an ensemble of algorithms that will start to evolve differently after some time and lead to different "you's". Count Iblis (talk) 19:57, 27 April 2012 (UTC)

I don't think we know enough about the brain to say that free will is an illusion. Of course, this also requires that one precisely define "free will"; obviously there is a difference between things I choose not to do and things I am unable to do (or, conversely, things I choose to do and things I can not stop myself from doing). And obviously there will be a gigantic gray area where those things overlap; I could choose not to bite my nails if I tried very hard but it's not worth the effort involved to break the habit. Heck, maybe the whole thing is gray area. We know that a sufficiently complex "program" can exhibit the illusion of free will, but as we have never built a computer even close to as complex as the human brain, so how can we say that free will is not genuine? -RunningOnBrains^(talk) 20:11, 27 April 2012 (UTC)

I agree with running on this. Certainly, if the entire functioning of the brain were determinable from an initial state, we might feel comfortable saying that there is no free will. But we don't know that that's true. We know that the basal rate of pre-synaptic vesicle release is a stochastic, rather than deterministic, event. But then, no one knows if such vesicular release has any actual impact on neuronal function. But the point is, it is a reasonable hypothesis that the output (thought) of the human brain, even given a known initial state and a controlled external environment, is not deterministic, but stochastic. Even if that were true, however, it's still a far cry from proving the existence of free will. Instead of saying someone's thoughts are pre-determined, you would be saying that their thoughts are random. Anyway, conclusion: we don't frickin' know. Someguy1221 (talk) 20:50, 27 April 2012 (UTC)

Re Sturat: That's not obvious at all. How do you know that I can control what I say? Widener (talk) 01:01, 29 April 2012 (UTC)

You may find Game theory sheds some light on decisions. I find it fascinating, personally, and it sheds light on decision making that comes from a mathematical perspective. --TammyMoet (talk) 09:15, 28 April 2012 (UTC)

(warning: fringe ideas ;) ) I think what people truly want when they talk about "free will" is neither predetermined will according to some computational algorithm, nor random will that is just a toss of the dice. What seems to me to be implied is will without causality, i.e. causality violation - will which is not determined by past events, even random events. So to me the origin of free will seems tied up with the notion of the time travel of information, i.e. precognition. Only the existence of a fixed, immutable future makes genuine free will possible in the present. See also [12]. Wnt (talk) 00:21, 29 April 2012 (UTC)

Steve is speaking about the Mind–body problem, he argues for monism/against dualism. You will also be interested in free will and determinism. While I do believe I was determined to write this as I know of nothing which has the ability to actively choose (for humans, all their actions are merely responses to stimuli, ergo they do not actively choose), there is no doubt I have the illusion of choice and that I am responsible for all my choices. Unique Ubiquitous (talk) 01:04, 29 April 2012 (UTC)

You may also be interested in randomness as if true randomness does exist as some quantum mechanics studiers believe, this could mean determinism is false. Though this would have no bearing on whether humans have control over themselves as humans have no control over the randomness of molecules, their actions would then simply be at the pleasure of both external stimuli and randomness. Unique Ubiquitous (talk) 01:19, 29 April 2012 (UTC)

I actually had a flash of insight last night, a realization that in essence yields a "Theory of Everything" (namely: every property in the universe, including conciousness, is a natural progression of patterns arising from subtraction over the integers) that finally, at least in my mind, answers that question once and for all. I won't bore you with the details, but in a nutshell: the universe is at once both completely deterministic and yet, due to it's infiniteness (and thus limitless in possibility), *entirely* guided by free will. Initially that may sound a little cliched, but with a bit of introspection it actually makes quite a bit of sense. No, really. :) Sebastian Garth (talk) 04:04, 29 April 2012 (UTC)

photoelectric effect - electron from K shell why?

i asked this question before on 24th April..well at that time i didnt had credible source to support my doubt...

Ques: isnt photoelectric effect in any way connected to Auger effect. In Wiki's article under Discovery section "High-energy X-rays were applied to ionize gas particles and observe PHOTOELECTRIC electrons." So it is true that electron in photoelectric effect is knocked out of K shell rather than OUTERMOST SHELL ( as written in Photoelectric effect article)....thanks--Myownid420 (talk) 17:12, 27 April 2012 (UTC)

The photoslectric effect can be caused by any photon with enough energy. Higher energy photons can dislodge the inner electrons, perhaps from the K shell, but the UV photon is more likely to only have enough energy to take out an outer electron. FOr high enough energy photons the inner electron will have a greater relative cross section. Graeme Bartlett (talk) 09:08, 28 April 2012 (UTC)

That's a novel one: photoseletric effect. Plasmic Physics (talk) 09:31, 28 April 2012 (UTC)

If you were to pick one decade that the telephone became 'mainstream'...

... what would it be? I had a look at a couple articles on the telephone and Timeline of the telephone but couldn't really find an answer. Thanks. Vranak (talk) 18:06, 27 April 2012 (UTC)

A good estimate for decade of widespread popularity/ market penetration will vary wildly by country and region. That is, long after most households had a phone in the USA, they were still a high luxury in other parts of the world. So, can you tell us what regions your are interested in? SemanticMantis (talk) 18:12, 27 April 2012 (UTC)

USA. Vranak (talk) 18:30, 27 April 2012 (UTC)

I found this graph of technology adoption on a blog, so it's not necessarily an authoritative source, and I'm not sure if it's referring to the US specifically. From a glance, it looks like it could reasonably describe the US. Certainly not the world--I wouldn't say half of the world had internet access in 2000. So according to the graph, I'd say the 50s, if you were to name a specific decade; that looks like when adoption broke the 50% mark. Perhaps the late 40s. By the 60s, it looks like it was reasonable to assume a given person had a phone. Short answer: the 50s, give or take a decade. --BDD (talk) 18:42, 27 April 2012 (UTC)

Thank you. Vranak (talk) 18:43, 27 April 2012 (UTC)

Resolved

The vertical axis label is slightly cut off, but it looks like it says "Percent of US households", so I'm pretty sure it is referring to the US specifically. --Tango (talk) 19:18, 27 April 2012 (UTC)

That depends a bit on how one defines 'mainstream', as well. Is it 'knows what a telephone is', or 'would be able to use a telephone if handed one', or 'has one in one's workplace', or 'has one in one's own home'? That last definition is probably the most restrictive, though one could certainly argue that the telephone became 'mainstream' once most businesses had one (something that likely happened long before they were in most homes). Historic U.S. census data says that in 1960, 21.5% of households did not have a telephone. (That falls to 13% in 1970, and all the way to just 2.4% in 2000.) On the other hand, the 1960 data also show significant state-to-state variation. Larger states with poorer or more remote populations tended to have vastly lower levels of home telephone ownership—55% of Mississipians and 41% of Alaskans were without telephones, whereas just 9% of Connecticuters were phoneless. Unfortunately, I haven't been able to find a source of similar numbers for pre-1960. TenOfAllTrades(talk) 19:33, 27 April 2012 (UTC)

Public perception may be more important than the actual statistics of ownership. A technology may be culturally normalized and 'mainstream' long before a majority of the population has access to it. By the 1930's, telephones were ubiquitous in films, and most people saw films. Hence, the idea of the telephone would have been more or less universally known and regarded as normal, even if it remained out of the hands of most people. Even while the majority were still phoneless, they might have begun to feel themselves unusual or behind the times in this regard. LANTZY^TALK 19:53, 27 April 2012 (UTC)

I'd go a couple decades before when the majority of homes had their own telephone, as there was a period when they were rather expensive, so people had party lines or shared phones, where maybe there was one phone in the hall of the apartment building, and everybody used it. You can see this from movies from this period (heck, even in college I shared a phone with the student next door). So, they were still using telephones, even if they didn't have one in their home. StuRat (talk) 20:28, 27 April 2012 (UTC)

I'd go with the 1930s too. There were payphones back then (the article states that by 1925, New York City alone had 25,000). Of course, that was advance preparation for the arrival of one special illegal immigrant. Clarityfiend (talk) 20:51, 27 April 2012 (UTC)

It was so very confidently predicted that Thomas E. Dewey would beat Harry S. Truman in the United States presidential election, 1948, that the Chicago-Tribune put out its edition without waiting for the actual results, with the now famous headline "Dewey Defeats Truman". The result, of course, was the reverse. Our article says:

• "Part of the reason Truman's victory came as such a shock was because of as-yet uncorrected flaws in the emerging craft of public opinion polling. A political theory supported by many pollsters (and largely discredited by the 1948 election) held that voters had already decided who they would support by the time the political conventions ended during the summer, and that few voters were swayed by the campaigning done during the autumn. As a result many pollsters were so confident of Dewey's victory that they simply stopped polling voters weeks before the election, and thus missed a last-minute surge of support for the Democrats."

But another reason I’ve been told is that the polling was done mainly by phone, and this led to skewed results since a statistically significant number of Americans still did not have their own phone at that time. -- ♬ Jack of Oz ♬ ^{[your turn]} 22:47, 27 April 2012 (UTC)

This wouldn't be a problem if phone owners and non-owners were evenly distributed. However, those without phones were more likely to be poor and vote for the Democratic Party, so that does skew the results towards predicting a Republican Party victory. StuRat (talk) 23:17, 27 April 2012 (UTC)

A magazine called The Literary Digest made an even worse assessment of one of FDR's campaigns. Their survey, thanks to flawed polling techniques, indicated FDR would lose big in 1936. Instead, FDR won in a landslide, and the magazine went bust. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:02, 27 April 2012 (UTC)

~ Health-Related Questions: For Only Knowledge & Experienced People of Excellence Only ~ [NOT SLOVED]

1) what is the most reputable rankings for Maternity Hospitals?

2) what are the 1-2 most reputable ranking for each section on mastersinhospitaladministration.com/2011/hospital-rankings-in-the-usa-the-ultimate-list/ -- include one sentence as to why

3) what is the average adult hip size, or average range of hip sizes?

4) what is the average adult waist size, or average range of waist sizes?

Thingstofollow (talk) 20:59, 27 April 2012 (UTC)

collapsing off-topic digression — Lomn
The following discussion has been closed. Please do not modify it.
Pardon me. You've no right to demand that only persons of specific (but unstated) ability or knowledge respond to your query. You've no right to require that our answers should be of a particular length. And in three of your four questions, you have failed to give us enough information about the area you are interested in. You are not entitled to any sort of answer whatever. And you can't spell "solved". AlexTiefling (talk) 21:48, 27 April 2012 (UTC) Wow, you really need to strike that and apologize. 65.95.23.172 (talk) 22:13, 27 April 2012 (UTC) I consider myself a "Knowledge & Experienced People of Excellence". But would you rather trust a random stranger on the internet or these people who have done extensive research on the topic? Statistics for USA Statistics for Japan -RunningOnBrains(talk) 22:24, 27 April 2012 (UTC) I really need no such thing. The OP has been peremptory and demanding, and gave us an incomplete question. I don't expect an apology from them, and they needn't expect one from me. AlexTiefling (talk) 22:33, 27 April 2012 (UTC) Your response was reasonable. No need to strike. ←Baseball Bugs What's up, Doc? carrots→ 22:51, 27 April 2012 (UTC) Thanks - I have no intention of striking. AlexTiefling (talk) 23:06, 27 April 2012 (UTC) Insulting an IP for a spelling mistake, how pathetic. 65.95.23.172 (talk) 22:52, 27 April 2012 (UTC) The OP isn't an IP user; they're registered. And I picked on the spelling mistake because of its position, the rudeness of the query, and the juxtaposition of the error with the demand for answers only from the learned. I generally try to be civil here, but there's no absolute reason why being a schmuck should earn you immunity from being called a schmuck. AlexTiefling (talk) 23:06, 27 April 2012 (UTC) Particularly when there's no question that we all understand the OP's intent, there's no need for this sort of discussion on the RD proper. Feel free to ignore questions you find insulting, demanding, childish, malformed, or otherwise bad -- I do it all the time. It's remarkably effective. — Lomn 23:28, 27 April 2012 (UTC) Feel free to stop being a nanny. ←Baseball Bugs What's up, Doc? carrots→ 04:10, 28 April 2012 (UTC)

For those with eyes to see, look at Q.2 and tell me if this isn't a classic homework question. -- ♬ Jack of Oz ♬ ^{[your turn]} 22:28, 27 April 2012 (UTC)

I thought so, but the whole thing is so asinine I'm trying to work out what educational institution would set such an exercise. AlexTiefling (talk) 22:33, 27 April 2012 (UTC)

I numbered the questions, but won't answer, because I might not be a "person of excellence". StuRat (talk) 22:41, 27 April 2012 (UTC)

You're obviously not a person of excellence because you inserted spaces at the start of your lines, rendering the text mainly unreadable. I've corrected your shocking errors. -- ♬ Jack of Oz ♬ ^{[your turn]} 22:44, 27 April 2012 (UTC)

I'm trying to figure out what "sloved" means. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:51, 27 April 2012 (UTC)

It will have to remain an unsloved mystery. AlexTiefling (talk) 23:06, 27 April 2012 (UTC)

Maybe a slove is a portmanteau of a "slithy tove". ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:10, 28 April 2012 (UTC)

only if it 'twas brillig... --Jayron32 04:18, 28 April 2012 (UTC)

For the last, here is a CDC page from 2008 with waist sizes, and many other physical dimensions, broken down by gender, age, and ethnicity, with the average, standard deviations, and various percentiles provided. Hip sizes could be pretty well estimated by multiplying waist sizes by around 1.1 for men and around 1.3 for women. — Lomn 23:41, 27 April 2012 (UTC)

Since my constructive (if slightly snarky) response was archived with the above, I'm going to repeat it here:

I consider myself a "Knowledge & Experienced People of Excellence". But would you rather trust a random stranger on the internet or these people who have done extensive research on the topic? Statistics for USA Statistics for Japan -RunningOnBrains^(talk) 02:26, 28 April 2012 (UTC)

Apologies, Running, I somehow missed those links when archiving the rest of that digression, and did not mean to hide useful answers. — Lomn 20:02, 28 April 2012 (UTC)

April 28

The new "Xi_b^*" baryon

Is http://www.sciencedaily.com/releases/2012/04/120427095621.htm trying to write "$\Xi _{b}^{*}$"? Whose fault was it that the TeX got put into a press release?

More importantly, what will the Wikipedia article on the new particle be named? 70.58.10.111 (talk) 04:24, 28 April 2012 (UTC)

See Xi baryon for more information and further reading on this class of particles. --Jayron32 04:49, 28 April 2012 (UTC)

The new particle is not yet included in our article. The quark content of the new particle is said to be up/strange/bottom. With the naming convention described in our article, this should be called $\Xi _{b}^{0}$, but this is already a known particle. I don't know what the asterix is supposed to indicate, high energy unstable state perhaps? SpinningSpark 11:18, 28 April 2012 (UTC)

To quote the original reference's abstract (arXiv:1204.5955v1), "the $\Xi _{b}^{*0}$ baryon, the J^P = 3/2⁺ excitation of the $\Xi _{b}^{0}$." DMacks (talk) 16:56, 28 April 2012 (UTC)

What is this black substance ?

http://img804.imageshack.us/img804/7756/image1os.jpg and http://img4.imageshack.us/img4/9763/size2k.jpg what is black substance in these photos ? — Preceding unsigned comment added by 182.185.194.68 (talk) 10:44, 28 April 2012 (UTC)

I'm guessing from context that it's cannabis resin, but these photos are awful, and you need to give us better context. AlexTiefling (talk) 11:08, 28 April 2012 (UTC)

I can't convince myself the black object in the first picture is the same as the brown one in the second. The first one looks like it might be wrapped in black plastic - maybe the pictures didn't specify it was unwrapped between shots? From context I'm thinking the second one is a brownie, but that's just my stomach talking. ;) Wnt (talk) 13:05, 28 April 2012 (UTC)

I think you are right these seems to be two separate objects. I have added more images, http://imm.io/nvhd, http://imm.io/nvj3, http://imm.io/nvk7, http://imm.io/nvkV, http://imm.io/nvlG, http://imm.io/nvoM, http://imm.io/nvpx, http://imm.io/nvpU, http://imm.io/nvqu. Some have been cropped and some are in original size. Hopefully these will be of help. — Preceding unsigned comment added by 182.185.194.68 (talk) 14:35, 28 April 2012 (UTC)

I don't know if any of these things is the same as any other. There are certainly more than two or three different objects. There might be a second one of the same "brownie" as the second original image ([13]). I still keep picturing brownies, also brownie batter [14] - if these pictures are from a medical marijuana user I'd believe it, since many of them prefer to avoid smoking for health reasons. Wnt (talk) 16:45, 28 April 2012 (UTC)

Never heard of hash brownies? --TammyMoet (talk) 17:30, 28 April 2012 (UTC)

Well this is certainly not marijuana for medical use, as too many cigarettes can be seen in the photos. Can it be Charas, where taken in Pakistan. — Preceding unsigned comment added by 182.185.194.68 (talk) 19:37, 28 April 2012 (UTC)

Sure, it could be. It could also be many other things. These photos are not enough for a positive identification of any sort. Perhaps if you could touch it, smell it, taste it, or burn it, you could narrow down the possibilities. Charas should behave rather differently than e.g pitch under a few of these basic tests. 96.235.227.66 (talk) 00:50, 29 April 2012 (UTC)

Presence of Joint (cannabis) confirm marijuana smoking, is charas quite plastic ? I mean it's shape can easily changed ? — Preceding unsigned comment added by 182.185.194.68 (talk) 01:59, 29 April 2012 (UTC)

Freezing

Why does hot water freeze faster than cold water? --108.206.4.199 (talk) 13:54, 28 April 2012 (UTC)

Mpemba effect#Causes has some explanations - which pertain depends on the specific experimental setup. -- Finlay McWalterჷTalk 14:01, 28 April 2012 (UTC)

... and, of course, the statement, as given, is false in many circumstances. Dbfirs 15:36, 28 April 2012 (UTC)

As with several other of the OP's ref desk questions. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:10, 29 April 2012 (UTC)

This is User:Tango's favorite subject. :) Count Iblis (talk) 15:38, 28 April 2012 (UTC)

Fortunately, the photos didn't come out very well! --Tango (talk) 02:21, 29 April 2012 (UTC)

Permanent marking of stolen clothing

IMHO there is a red color, which marks stolen clothing permanently. --84.61.181.19 (talk) 17:00, 28 April 2012 (UTC)

Could you phrase that as a question? SpinningSpark 17:26, 28 April 2012 (UTC)

Who says there is a red color, which marks stolen clothing permanently? —Tamfang (talk) 17:36, 28 April 2012 (UTC)

Someone with kleptomania and chromatopsia ? Sean.hoyland - talk 18:02, 28 April 2012 (UTC)

What is the name of the red color, which marks stolen clothing permanently? --84.61.181.19 (talk) 18:55, 28 April 2012 (UTC)

Dye pack, which is mostly about banks, lists Disperse Red 9 as commonly used in money packs. But I don't know about clothes. --Mr.98 (talk) 20:30, 28 April 2012 (UTC)

Do we truly not have an article on dye tags, as described in this HOWTO on removal of the tags (should the clerk fail to do so)? I thought that we had an article on everything. -- ToE 03:37, 29 April 2012 (UTC)

There are a couple article sections on the topic, but neither of them say anything about the type of ink or dye that's used: Retail loss prevention#Ink tags and Electronic article surveillance#Occasional vs. informed shoplifters. Ink tag just redirects to the latter article. Red Act (talk) 04:10, 29 April 2012 (UTC)

I just changed the redirect target to the former which seems more relevant. SpinningSpark 10:13, 29 April 2012 (UTC)

It doesn't answer the question, but this book has a lot of interesting information. The first ink tags were made by Colour Tag and were quite vicious, using a toxic dye and a tendency to explode when removed due to being filled under pressure. Modern versions use a non-toxic and non-flammable dye but the book does not name the chemicals. I imagine that each manufacturer has their own recipe - note that they come in a variety of colours, not just red. SpinningSpark 10:28, 29 April 2012 (UTC)

What a strangely crude device! Every retailer must have a tool to get the tags off, so any serious organized shoplifting gang must have them. And as shown in the "howto" site it apparently isn't rocket science even for the random person to defeat them. I haven't seen anything I recognize as similar to that in the U.S. Wnt (talk) 11:25, 29 April 2012 (UTC)

Sensormatic is/was another major vendor. I remember seeing various sorts of these things all over the US even within the past few years, usually looking like a large opaque off-white clothes-pin or 2-inch square. DMacks (talk) 11:43, 29 April 2012 (UTC)

Aquifer drawdown and cloud cover.

I was about to mark a statement in the groundwater article as dubious, but then I noticed that the same statement can be found in a lot of related articles. The statement conflicts with my understanding of phase equilibrium. Here are the articles I checked:

Groundwater

Aquifer drawdown or overdrafting and the pumping of fossil water increases the total amount of water within the hydrosphere subject to transpiration and evaporation processes, thereby causing accretion in water vapour and cloud cover, the primary absorbers of infrared radiation in the Earth's atmosphere. Adding water to the system has a forcing effect on the whole Earth system, an accurate estimate of which hydrogeological fact is yet to be quantified.

Overdrafting

Aquifer drawdown or overdrafting and the pumping of fossil water increases the total amount of water within the hydrosphere subject to transpiration and evaporation processes, thereby causing accretion in water vapour and cloud cover, the primary absorbers of infrared radiation in the earth's atmosphere[citation needed]. Adding water to the system has a forcing effect on the whole earth system, an accurate estimate of which hydrogeological fact is yet to be quantified.

Water crisis

Aquifer drawdown or overdrafting and the pumping of fossil water increases the total amount of water within the hydrosphere subject to transpiration and evaporation processes, thereby causing accretion in water vapour and cloud cover, the primary absorbers of infrared radiation in the earth's atmosphere. Adding water to the system has a forcing effect on the whole earth system, an accurate estimate of which hydrogeological fact is yet to be quantified.

Water cycle

Aquifer drawdown or overdrafting and the pumping of fossil water increases the total amount of water in the hydrosphere[18] that is subject to transpiration and evaporation thereby causing accretion in water vapour and cloud cover which are the primary absorbers of infrared radiation in the Earth's atmosphere. Adding water to the system has a forcing effect on the whole earth system, an accurate estimate of which hydrogeological fact is yet to be quantified.

Hydrosphere

Aquifer draw down or over drafting and the pumping of fossil water increases the total amount of water in the hydrosphere[4] that is subject to transpiration and evaporation thereby causing accretion in water vapor and cloud cover which are the primary absorbers of infrared radiation in the Earth's atmosphere.
I could add a dubious template to all of them, but how many more are there? And is my doubt justified? Ssscienccce (talk) 17:34, 28 April 2012 (UTC)

Not only dubious, but poor English. This is a pretty serious problem you've stumbled on, as it appears to be on many pages for over a year, I'm gonna see how deep the rabbit hole goes... -RunningOnBrains^(talk) 19:15, 28 April 2012 (UTC)

Just another four I think, Fossil water, Drawdown (hydrology), Water table & Aquifer. Mikenorton (talk) 19:22, 28 April 2012 (UTC)

I was able to track it down to a single IP in February 2011, using this article as a source on some pages. Seems pretty dubious to me, but it has been postulated by some scientists (now that I actually know what the IP was TRYING to say). Still, per WP:UNDUE, it doesn't belong in most if not all of these articles, so I'm going to remove it. -RunningOnBrains^(talk) 19:23, 28 April 2012 (UTC)

Just a note, I did end up leaving a sentence about sea-level rise in most of the articles, as that part is backed up by the cited study. All that stuff about extra water vapor/etc. is pure original research, and was removed. -RunningOnBrains^(talk) 19:41, 28 April 2012 (UTC)

sodium metasilicate

my understanding is when sodium metasilicate comes into contact with water it becomes especially caustic kind of like calcium oxide does. My question is when it contacts with water does it react to produce a less caustic chemical kind of like calcium oxide becomes calcium hydroxide? Or does it stay as sodium metasilicate. If it does react how long does it take?--64.38.226.88 (talk) 19:38, 28 April 2012 (UTC)

No, sodium silicate readily dissolves into 2 Na⁺ + SiO₃^-2 and the evaporation residue will mostly be the Na₂SiO₃·9H₂O hydrate. It's a very strong caustic base when saturated, and dangerous as such. 70.58.10.111 (talk) 01:36, 29 April 2012 (UTC)

SiO²⁻
₃ + H
₂O ←→ SiH
₂O²⁻
₄

SiH
₂O²⁻
₄ ←→ SiO
₂ + 2HO⁻

Plasmic Physics (talk) 08:42, 29 April 2012 (UTC)

April 29

How do I mimic static over the cellphone?

In some situations, I feel the need to mimic increasing static on a phone before disconnecting. It needs to sound convincing, so what are the best methods? Thanks. --68.102.29.129 (talk) 02:26, 29 April 2012 (UTC)

Stand outside, hold phone into wind. --Mr.98 (talk) 02:53, 29 April 2012 (UTC)

This isn't always convenient when the day is calm, and when I'm in a bad position to go outside and hold the phone into the wind. Are there other methods just as good? --68.102.29.129 (talk) 03:36, 29 April 2012 (UTC)

Modern digital communication rarely injects Gaussian noise into the audio channel. A dropped call often occurs without warning, and the call simply disconnects. If you're seeking to realistically simulate a call interrupted by poor reception, simply disconnect at a random time. If you actually want to play "static" over the microphone for some other reason, consider recording some white noise and playing it in the background using an audio player. Nimur (talk) 04:10, 29 April 2012 (UTC)

Well, there is comfort noise. DMacks (talk) 09:01, 29 April 2012 (UTC)

I don't know about cell phones in particular, but in general simply blowing directly onto a microphone tends to produce a surprising amount of noise, unless you're using a dead cat or something. Red Act (talk) 04:40, 29 April 2012 (UTC)

The best trick might be to hang up while you yourself are talking, reducing the possibility that the other party will think you hung up on them. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:52, 29 April 2012 (UTC)

I agree - digital cellphones don't often get noisy before dropping out, but what they often do is chop up / interrupt your voice a few times before disconnecting. You could simulate this by rapidly placing and removing your finger over the microphone hole while continuing your talking. On most modern phones, it's only a single hole 0.5 to 1 mm diameter. If you do this more than once or twice to the same caller, they'll will catch on to what you are doing though. Wickwack121.221.228.248 (talk) 05:34, 29 April 2012 (UTC)

A Fibres in Frog Sciatic Nerve

Hello. Are the A-alpha fibres of the frog sciatic nerve the only component of A fibres that are myelinated? Thanks in advance. --Mayfare (talk) 18:20, 29 April 2012 (UTC)

Gravity

Physicists variously talk about gravity as an element of space-time, as gravity waves, and as gravitons. Are these related in some way or are they three different views of gravity? — Preceding unsigned comment added by Gstrom47 (talk • contribs) 20:19, 29 April 2012 (UTC)

Gravitational waves and viewing gravity as the curvature of spacetime are part of the same model of gravity, general relativity. Gravitons are an attempt to extend quantum field theory to gravity, which is a different approach in that general relativity doesn't deal with quantum mechanics at all. Red Act (talk) 21:02, 29 April 2012 (UTC)

Why were the X-15 rocket-powered aircrafts retired?

Why were the X-15 rocket-powered aircrafts retired? 82.31.133.165 (talk) 21:09, 29 April 2012 (UTC)