Wikipedia:Reference desk/Archives/Science/2012 December 25

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December 25

Acetone

I used Acetone in my car. The vapors are so strong that it has irritated my eyes. Is there a vapor suppressing foam I can buy. Do you know any retailers selling this? Is there anything else I can use. What else can I do. Thanks — Preceding unsigned comment added by 174.111.55.161 (talk) 02:45, 25 December 2012 (UTC)

Open doors and big fan for a day or two. --Jayron32 02:47, 25 December 2012 (UTC)

You didn't learn from when you had this problem last year? DMacks (talk) 05:55, 25 December 2012 (UTC)

Twice. --ColinFine (talk) 23:20, 28 December 2012 (UTC)

Or are you saying you can still smell it 16 months later ? StuRat (talk) 06:13, 25 December 2012 (UTC)

Nothing new under the sun, huh? Any chance Keeeeeeith is baaack? μηδείς (talk) 20:55, 25 December 2012 (UTC)

surface tension

why is there a colouring change when soap is reacted with milk? — Preceding unsigned comment added by 117.196.135.236 (talk) 16:40, 25 December 2012 (UTC)

What color does it change into? 76.23.194.179 (talk) 17:16, 25 December 2012 (UTC)

Ordinarily, milk is coloured white because of the Tyndall effect. When soap is added, the colloidal particles are fully dispersed. Plasmic Physics (talk) 20:37, 25 December 2012 (UTC)

balloons and fire

direct contact of a blowed balloon with fire can burst that balloon but when that balloon filled with water show to the fire it does not burst . why ? — Preceding unsigned comment added by 117.196.135.236 (talk) 16:48, 25 December 2012 (UTC)

Gases expand greatly when heated. For most situations, gases are governed by the ideal gas law: pressure(P) * volume(V) = number of gas particles (N) * boltzmann constant(k) * temperature(T). Or given a certain pressure (gas in a balloon will expand until internal pressure equals atmospheric pressure), V = N*k*T/P. If you heat a gas by flame, it will expand so much (the temperature will increase rapidly) that the balloon will burst. Water does not expand that much when heated, in fact it has a very high heat capacity. You have to convert the water into gas (i.e. by heating at 100C) to burst the balloon. 76.23.194.179 (talk) 17:15, 25 December 2012 (UTC)

I think what's more relevant is the heat capacity of the water inside the balloon which prevents the skin of the balloon from so quickly reaching melting point. I have never seen a balloon expand first before exploding due to a flame, which is what you are implying, IP 76, would happen. μηδείς (talk) 20:54, 25 December 2012 (UTC)

Once, my high school chemistry teacher filled a balloon with hydrogen gas and set the balloon on fire. It did not burst until the balloon burned through, igniting the hydrogen. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 07:22, 26 December 2012 (UTC)

Another example that illustrates the heat capacity explanation of μηδείς is a burning candle standing in cold water: you should be able to get it to burn down a little way below the water surface level protected by a thin-walled cylinder of unmelted wax. — Quondum 07:37, 26 December 2012 (UTC)

I agree with Medeis - another common demonstration is placing a paper cup over a candle or bunsen burner. The water absorbs heat from the paper quickly enough that the paper doesn't ignite. You can actually bring the water to a boil this way. This is clearly the same kind of effect you describe, and the expansion of the water or air has nothing to do with it. 209.131.76.183 (talk) 18:01, 26 December 2012 (UTC)

You can boil water over a camp fire in a plastic soda bottle. Vespine (talk) 22:05, 26 December 2012 (UTC)

In fact, with a little skill, you can even melt lead or tin in a paper crucible... 24.23.196.85 (talk) 01:11, 27 December 2012 (UTC)

Those are three interesting demonstrations none of which I have ever seen done. μηδείς (talk) 01:33, 27 December 2012 (UTC)

Interesting idea. I found [1] which makes no big deal of it. Indeed lead has melting point 621.43 F, which is greater than the legendary 451, but I haven't looked into the details. Wnt (talk) 15:47, 27 December 2012 (UTC)

Actually, Bradbury was wrong -- paper burns at 451 Celsius, not Fahrenheit. (Which doesn't negate his main point about the negative effects of censorship.) 24.23.196.85 (talk) 00:53, 28 December 2012 (UTC)

tests for reality

What are some philosophical and scientific tests to help verify that reality is real, i.e. what we perceive is not an illusion? I know a recent one mentioned in the news is some big particle physics experiment or something. 76.23.194.179 (talk) 17:19, 25 December 2012 (UTC)

There are no scientific tests to prove to yourself that you are real. It's one of those things you need to take on faith. Philosophically, it's a question almost as old as philosophy itself. Different philosophers have approached the question in many different ways. Plato had the Allegory of the Cave for example. Rene Descartes took the rather pragmatic "cogito ergo sum" as his approach. If you want the philosophical end of being and existence, you'll want to look into the well-mined field of Ontology which deals with the question in some detail. --Jayron32 17:53, 25 December 2012 (UTC)

Claiming that we are in a simulation can exclude all arguments "pro-reality." Everything that you perceive, feel or think is simply part of this simulation. It's like the belief in god, everything that point towards a materialistic universe without a god is simply the wish of god. OsmanRF34 (talk) 20:35, 25 December 2012 (UTC)

Email me next time you're in New York. I'll come slap you up the head. You can tell me whether it's real or not. (Hopefully you aren't upset by not really being slapped upside the head.) μηδείς (talk) 20:51, 25 December 2012 (UTC)

This is the classic Johnsonian argumentum ad lapidem - the slapping may _feel_ real, but how can the slappee know that it _is_ real? Tevildo (talk) 21:17, 25 December 2012 (UTC)

Ask yourself how a brain in the vat, receiving the same inputs as your brain, would perceive the world any differently. (Answer: it wouldn't.) Contrary to what Jayron says, you don't "take on faith" the assumption that reality is real; you admit that you don't know. That may be hard for people who usually make up what they don't know, but if you don't know, then you don't assume anything.

That said, people have tried to make various arguments about why it's unlikely that we're brains in vats. Most of them reduce to Occam's razor. If we're brains in vats, there must be an external reality in addition to the reality that we experience, with intelligent beings who have the motivation to put brains in vats. Since this scenario is far more complicated and has no more explanatory power, we assume we're experiencing reality. --140.180.249.194 (talk) 21:48, 25 December 2012 (UTC)

There is no difference between taking something on faith and admitting that you don't know. They are two perfect synonyms for the same concept. In either case, you still need to operate as though what you perceive is reality. Either you admit you don't know, but you behave as though it were real, or you accept on faith that it is real. It amounts to the same thing. --Jayron32 23:06, 25 December 2012 (UTC)

The solution is simple. Define what is real by setting some simple parameters and conditions. If something passes those tests, it's real for the purposes of the definition. If it doesn't, it's not.

Now, whether these supposedly real things are really real ... well, who gets to say? It's all subjective. There isn't any such thing as objective reality. If you don't believe me, please provide one counter-example. That's all it would take. Nobody's ever succeeded, and they're never going to, because whatever we know of anything in the universe is what our senses tell us. Those senses are essential for us to perceive or know anything, but they also act as a barrier between us and those things. We can never know those things directly, extra-sensorily. Those things include everything about ourselves that we assume to be real. Descartes might have had a point with his "cogito ergo sum", because it's hard for a non-existent entity to think. But how do we know we're thinking? How do we know a rock or a tree don't think? What is thought, anyway? Do we get to decide what thoughts we have, or are we victims of "some vast eternal plan"? Does the universe really exist? Who could ever provide definitive and incontrovertible answers to these questions? Nobody. Doesn't stop us asking the questions, though. We're left with what we can perceive, and we try and work with that. It seems to be enough for most people. -- Jack of Oz ^[Talk] 22:38, 25 December 2012 (UTC)

I don't know which "big particle physics experiment" you're referring to - but it doesn't matter what it said because it can't possibly prove the existence of "reality" for any individual because you can't know whether the report of it that you thought that you read is "real". It's only your senses that report that this is what it said - and you know that you can't trust those senses. Truly, the only thing that gives you even a hint of a solution is something vague like Occam's Razor. The simplest and most practical and useful thing you can do is to assume that your senses are telling you the truth - until such time as it's proven that they are not.

I'd also like to suggest that it quite literally doesn't matter. So long as it's all consistent and your actions produce results in this seeming reality that seem correct, what do you care if we're really just brains in jars or a part of some alien intelligence's computer game? You still need to do the same things to avoid unpleasant feelings of hunger or thirst - your drives are still "real" to you and need to be attended to.

Conversely - we might find some strong pointers showing that the universe might truly be a simulation running in some mega-computer in the "real" universe. I'm spent my career as both a game programmer and a simulation programmer. It seems quite striking to me that there are a number of things that we observe about our universe that make it seem to have properties very much like the restrictions that a simulation might have:

1. Quantum theory. When you look at the very smallest things - their behavior is random and quantized. In a finite precision computer, that's exactly what you'd expect. There would be randomness due to things like roundoff error and because of that finite precision, you'd see quantised behavior in all sorts of very small system. Old flight simulators from the 1980's used to have a precision of 1/256th of a foot - if you lived in that simulation, you'd say that the laws of physics quantised all distances to a "plank length" of 1/256th of a foot and invent complicated 'laws of physics' to explain that.
2. Relativity. It's very convenient for the simulation for there to be a finite speed of light and a universal speed limit. It constrains the amount of the universe that you'd have to simulate with great precision and covers up the effects of latency between computers simulating different parts of the universe - and it also prevents humans from spreading outwards beyond the region which is simulated at high fidelity into further reaches of the universe where the computer could do a more sketchy simulation and not have to track ever single fundamental particle.
3. The Big Bang. That's a very convenient way to hide the finite nature of time. You can't have the simulation running forever - it has to have a fixed start time. It has to be impossible to see what happened before that time - and starting things off as a singularity makes a lot of sense. This also imposes a limit on the size of the observable universe - which, again, is handy if your computer has finite memory.
4. Why there is so little matter in all of this vacuum. Building your simulated universe like that allows you to have a vast universe with much less computational effort than if it were mostly full of matter.
5. Entropy. Highly organized systems take a lot of simulation time - allowing things to degenerate into low grade thermal 'noise' keeps the simulation within reasonable bounds. If the system became more organized as time passed, the simulation computer would start to run more and more slowly.

SteveBaker (talk) 04:01, 26 December 2012 (UTC)

Steve, none of this makes any sense. Quantum mechanics is not cheaper to simulate; it seems to be impossible to simulate a quantum system on a classical computer without exponential slowdown. Even accurately simulating a single proton is far beyond the ability of any supercomputer. The enormous cosmos we find ourselves in could be eliminated without any practical effect on our lives. Those vast reaches of space are not empty, but filled with CMBR photons, which are not quite randomly distributed but show a slight anisotropy, first seen with COBE, which has been faithfully preserved for billions of years. The universe was not made on a budget. -- BenRG (talk) 17:19, 26 December 2012 (UTC)

I'm not saying that quantum mechanics is simpler to simulate - I'm suggesting that it's an artifact of any simulation on a finite precision computer that you'll see quantisation and other bizarre behaviors if you look on a small enough scale. Of course simulating even a tiny piece of our universe (like one gram of water) is insanely far beyond what any technology we can imagine could to - but remember that the laws of physics out there in the "real" universe could (and almost certainly would) be very different from our own - perhaps there is no speed of light limitation? That would perhaps allow computers to be very much faster than they are in our universe and (conceivably) make simulating vast numbers of fundamental particles - even with quantum mechanics - a fairly simple business. I don't know (obviously) - but it seems to me that some of the stranger things that we find when we look hard enough could be revealing "bugs" or "artifacts" that might reveal the likelyhood that we're being simulated. SteveBaker (talk) 04:07, 27 December 2012 (UTC)

I think that makes a lot of sense, Steve. Actually the real universe could have supercomputers more vast in power than we could comprehend. Their laws of physics... Everything there could be different. We cannot compare what we can do here with what the "real" God-like simulators could. This would explain a lot about our random and mysterious universe. See simulation hypothesis. But even if we were really being simulated, what can we do? Life, whether simulated or not, will still continue. The universe is an enigma, indeed. Bonkers The Clown (Nonsensical Babble) 06:17, 27 December 2012 (UTC)

You still seem to be missing the fact that it's enormously harder to simulate a quantum world than a classical world. Quantization in quantum mechanics has no resemblance to the sort of discreteness you find in a computer. The state of a quantum computer is represented not by integers but by a vector in a complex vector space whose dimension is exponential in the number of qubits. Roundoff error loses data, and data loss at a fundamental physical level would violate the principle of unitarity which is an indispensable part of quantum mechanics. The idea that our world was designed for ease of simulation is idiotic. All evidence suggests exactly the opposite. -- BenRG (talk) 08:12, 27 December 2012 (UTC)

Go easy there. Both sides are making unjustified assumptions, presumably drawn from empirical experience. The so-called probabilistic nature of quantum mechanics does not suggest round-off error at all, but any observation of "glitches" (never observed) would indeed be interesting evidence in this direction. On the other side, to assume that the quantum world is inherently "too complex" for simulation, or that that the "parent reality" even has a time dimension is not justified. A simulation would only need to process the amount of information required to describe a quantum system, which rather counterintuitively does not grow by volume but rather by the surface area of a volume, thus making large systems more efficient to "simulate". — Quondum 09:53, 27 December 2012 (UTC)

@ Tevildo, it's called not the argumentum ad lapidem but the corollary argumentum I'd've slappèd 'im. And it;s hardly a fallacy. μηδείς (talk) 06:41, 26 December 2012 (UTC)

It is a fallacy, as you're not addressing the question, merely making the assertion "It's obvious that reality is real." If we define truth as "Whatever is obvious to Medeis" (or Dr Johnson), then our work here would be a lot easier, if a lot less useful. SteveBaker, as always, has provided an excellent answer - science can't address the general metaphysical question (our article noumenon covers it reasonably well) , but science can address the question "Is the world we percieve a simulation running on a computer in a world with the same characteristics as ours?" Tevildo (talk) 22:45, 26 December 2012 (UTC)

No, it's not a fallacy (not necessarily) unless one assumes that statements are only ever grounded in other statements, not physical/perceptual evidence. It's actually the request to prove reality which is fallacious, since an independent proof would have to be based on something outside reality. Aristotle recognized the futility of such questions, and I have long had the quote of him saying so at the top of my talk page. μηδείς (talk) 01:31, 27 December 2012 (UTC)

• (Not an answer, just a verbose and speculative exploration of the question; note that some of the first part follows on The Mind's I which is the most useful reference work I can think of and spoke of replacing neurons in the brain in a vat by a computer, a choose-your-own-adventure type book, etc.) It occurs to me that if the underlying algorithm of a "brain in a vat" were understood, i.e. that the actual data being "sensed" by "consciousness" could be defined as bits of information, then you could collect all the possible sequences of bits that could be sent to it and lay them out in a numerical table of all the experiences - not just sensory information but memory and belief as well - which any conscious being could ever possibly have. If so, you have a one-to-one mapping between every possible conscious experience and a number, and the laws of physics, any physics, in any possible parallel universe we can imagine (i.e. our method of consciousness, whatever that is) can be laid out as functions which successively map a series of numbers. In this way it would appear that all experiences are real in that they are all mathematical functions which eternally and immutably exist in the sense of any mathematical function. And yet ... we have the sense that not only is there one present but one past, i.e. that one possible physics is more important than the other. Is that merely the sensation of memory and specifically memory of rules, part of the premise for a given moment? What is the difference between such a number as it exists as any number, or when it is written down, or when it is encoded in flesh? Why is the experience of neurons as they fire a kind of 'consciousness' but not the experience of water as it reaches a rolling boil? (or is it?) I suspect that that our religion of causality is not actually based on any fact, that precognition is an important and dangerous phenomenon, and that its carefully regulated expression in the brain permits the effective creation of information via paradoxes, and its time inverse permits the destruction of information, and that these processes define the one and only consciousness, which is shared between all and only seen as distinct from one person to another due to the limitations of the input data. Wnt (talk) 05:19, 27 December 2012 (UTC)

• In case anyone here finds themselves a bit lost, this is a science reference board, not the whatever unlikely fantasy dreamland might exist board. Proofs of reality are far more than just subjective claims, otherwise some smart rocks might be deluded and still be insisting that other rocks have thoughts and that the world is flat and perched atop some animal's back despite some rather adequate evidence against these intriguing notions regarding the existence of even larger flat rocks. Thus, sometimes even sacred cows get burnt occasionally and, like marshmallows, can taste rather bittersweet when done. Yet despite how exceedingly difficult it might be at times to comprehend reality though, there is from within the unvarnished bowels of our esteemed wiki the article on scientific realism. Also, the OP eluded to a recent notable science experiment, which is probably the discovery of a particle believed to be the Higgs boson. --Modocc (talk) 14:37, 27 December 2012 (UTC)

Is the ability to fart in a controlled manner a rare talent or a mundane skill?

Both Flatulist and Flatulence remain silent on the matter. Is the ability to control one's abdominal muscles like this really incredibly rare, or is it a skill which can be achieved through experimentation and practice (at least in principle) by any average person – just like, say, belcanto technique (which doesn't require extraordinary talent to master, as far as I've been told, unless you wish to pursue it on a professional level; it's just really tricky because the muscles involved are so small and numerous and your teacher can't show you directly the way they move them or guide you, the same reason why it's relatively easy to teach a chimp hand gestures/signs since you can shape their hands the way you intend them to move, but talking, no way: same problem with the muscles in your abdomen) –, but that simply hardly anyone bothers to try to learn? Perhaps the real reason why flatulists are so rare is that people believe that you "just can't learn that", you've got to be a freak of nature? --Florian Blaschke (talk) 21:50, 25 December 2012 (UTC)

Le Pétomane indicates that he had some innate ability that was developed through practice. That is, his ability to take up and expel both air and fluids through his anus was something that was inborn, and over time he developed the inate ability into an entertainment act. --Jayron32 23:03, 25 December 2012 (UTC)

So it's like being able to wiggle your ears, except much, much rarer? And you are saying that the overwhelming majority of humanity are just innately completely unable to control these anal muscles (the sphincter?) consciously (at least this precisely)? Making Le Pétomane a genuine freak of nature? OK, but how about the medieval flatulists? The quote from Piers Plowman sounds as if the level of ability a medieval flatulist needed was not all that rare, at least. So perhaps Le Pétomane is not the best example of a flatulist because his case is too extreme/unique.

By the way, Le Pétomane is already halfway there compared to the freak which Knorkator describe in their song Ich bin ein ganz besond'rer Mann, because that man is not only able to suck liquids and other objects into his anus, but even drink and eat with it. Hilarious and brilliant. --Florian Blaschke (talk) 04:11, 26 December 2012 (UTC)

I would not conclude that it innately unachievable in general. There are numerous examples of potential coordination skills that are never practised by the vast majority of people and thus seem unattainable. Those that are never practised tend to atrophy (both the neural and muscular aspects). Like squinting, winking, raising an eyebrow, moving your eyes independently (cameleonlike), riding a bicycle, concious heart rate control etc. – with dedicated effort many of these skills can be acquired later in life, and would probably be acquired naturally if taught/observed from birth or early childhood. I have heard anecdotally of a a sect/group that learns rectal cleansing using this kind of control, which would suggest that this is just another skill that can in principle be acquired by a majority given sufficient effort. — Quondum 07:05, 26 December 2012 (UTC)

Thank you for confirming my suspicion. That's exactly what I was thinking. --Florian Blaschke (talk) 16:31, 28 December 2012 (UTC)

You can't teach a chimp to speak because they lack the equipment to do so. StuRat (talk) 06:57, 26 December 2012 (UTC)

Citation needed. They do not lack the necessary organs or neural pathways, so their inability is not a matter of principle; if anything, they lack the dexterity, which was exactly my point. See Viki (chimpanzee). --Florian Blaschke (talk) 16:37, 28 December 2012 (UTC)

I took the StuRat's comment to refer to the physiological equipment: "chimpanzees are not able to produce the sounds that make up human speech" as it says in the article you cited. This is not just a matter of dexterity, but also the shape of their vocal tract, which cannot produce many of the vowels (and disctinctions of vowels) found in Human language. IIRC Eve Spoke, by Philip Lieberman goes into this in some detail. --ColinFine (talk) 23:42, 28 December 2012 (UTC)

Exactly. Humans seem to have evolved different equipment specifically to support speech. StuRat (talk) 04:16, 29 December 2012 (UTC)