Wikipedia:Reference desk/Archives/Science/2012 December 28

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

December 28

Mr Edelweiss type of bird

In the film Nanny McPhee Returns, she has a bird named Mr. Edelweiss. What type of bird is he? — Preceding unsigned comment added by Donmust90 (talk • contribs) 02:05, 28 December 2012 (UTC)

he is a Jackdaw, from what I can ascertain via Google. AndyTheGrump (talk) 05:06, 28 December 2012 (UTC)

Name that fish (Halfbeak -- ballyhoo?)

Name that fish.

I was snorkelling in Cuba last week (near Playa Jibacoa, roughly halfway between Havana and Varadero). Lurking just under the water's surface near the reefs not far off shore, I saw a number of interesting fish, including the character pictured at right. My best guess is that it was roughly a foot long, including the 'beak'.

I'm pretty sure it's some sort of Halfbeak, and I think it might be a Ballyhoo. Is there anyone who knows their saltwater tropical fish who can confirm/narrow that identification? And is there an article that could use the picture? Thanks, KevinHadley (talk) 03:06, 28 December 2012 (UTC)

The ballyhoo article only contains a low-res drawing, so an actual pic would be a definite improvement. StuRat (talk) 05:40, 28 December 2012 (UTC)

It's a Ballyhoo. Darkness Shines (talk) 10:45, 28 December 2012 (UTC)

Can a tunnel flood?

Like a major one like the Lincoln Tunnel or the Channel Tunnel. ScienceApe (talk) 07:32, 28 December 2012 (UTC)

I fail to see why wouldn't it be possible. It must have a draining mechanism, which probably stops when everything is flooded. OsmanRF34 (talk) 13:17, 28 December 2012 (UTC)

The Holland Tunnel just flooded in Hurricane Sandy. You can even watch it [http://www.bloomberg.com/video/subway-tunnel-flooding-problems-in-new-york-K5yQpX6ARVKziYi~4HlRiQ.html. Rmhermen (talk) 18:24, 28 December 2012 (UTC)

Lincoln Tunnel was the only one that wasn't closed in NYC. --jpgordon^{::==( o )} 20:03, 28 December 2012 (UTC)

The Midtown Tunnel between Norfolk and Portsmouth, Virginia flooded in 2003 when maintenance crews were unable to completely close the floodgates in time due to (IIRC) a drainage grate or cover plate that had been welded in place. -- Tom N (tcncv) talk/contrib 00:23, 29 December 2012 (UTC)

I've often wondered, if the Transbay Tube were broken, how high the water could get in the Market Street stations; i.e., how much of each station is below sea level. —Tamfang (talk) 18:31, 28 June 2013 (UTC)

(YouTube link: How to Knit * Knitted Hat Top Down * How to increase)

The vid shows knitting with 3 or 4 needles. Is it possible to knit with say 7 needles?Curb Chain (talk) 08:18, 28 December 2012 (UTC)

See Circular knitting - no obvious reason why you couldn't use five or more double ended needles (they are sold in sets of four or five apparently), although these days you would most likely use circular needles. Mikenorton (talk) 09:06, 28 December 2012 (UTC)

As someone who always knits with circular needles, I can tell you they are not practical for smaller items such as socks, and 4 or 5 needles are the norm for knitting socks. No reason why 7 needles couldn't be used but it would be very complicated. I wouldn't want to try it. TammyMoet (talk) 09:52, 28 December 2012 (UTC)

Not without a knitting machine, anyway. --jpgordon^{::==( o )} 15:55, 28 December 2012 (UTC)

Those use hooks or latch hooks, not needles. Rmhermen (talk) 18:22, 28 December 2012 (UTC)

Or, as they commonly called, "latch hook needles". --jpgordon^{::==( o )} 19:50, 28 December 2012 (UTC)

Not by me. But they aren't knitting needles whatever their name. Rmhermen (talk) 20:08, 28 December 2012 (UTC)

Can curing of paints change tensile properties

We are painters doing powder and pvdf coatings on aluminum. Normally, aluminum alloy 6063 is used for door, window sections. However, in one specific case, we have got alloy 6082 T6 for pvdf coating job. PVDF coatings need to be cured at a temp of approx 230-240 degree C for 8 to 10 minutes, which, in general is specified by the paint manufacturers.

Would curing at this temperature and time bring some difference in the Fy or elongation/ tensile properties of the metal 6082? If so, to what extend. The mill finished extruded material received by us has a Fy 255 mPa.

Your opinion is awaited.

Regards, Sanjay — Preceding unsigned comment added by 122.161.52.208 (talk) 13:14, 28 December 2012 (UTC)

If you have a look at Steel#Material properties, you can see that heating may cause Recrystallization (metallurgy) of the alloy. Whether or not that will happen at that temperature is entirely dependent on the particular alloy's thermal behaviour. Considering the relatively low melting point of the alloy (555 °C), that does not seem unlikely to me.

For those who are looking for more information on the alloy: [1]. Plasmic Physics (talk) 19:08, 28 December 2012 (UTC)

telling if we are in a Virtual Machine

Suppose the universe might be emulated, just as we might emulate a few atoms of it once we have all the laws figured out. Propose strategies that we can follow to determine whether the physical universe is in fact being emulated in this sense or not. This is not homework. 91.120.48.242 (talk) 14:50, 28 December 2012 (UTC)

Similar questions have been asked here several times before, I recommend a search of the archives. Our most relevant article on the concept is Simulation hypothesis, which gives an overview of the problem and its history. From there you can jump to articles that seem relevant to you or follow the references. I notice that there is an original research tag at the top of the article, so you should be aware that some portions may be user speculation instead of being based entirely on reliable sources. 209.131.76.183 (talk) 15:54, 28 December 2012 (UTC)

If this is not a homework question, why is it worded like one? Propose strategies that we can follow to determine whether you are doing your own work. However, for the record, we can help with your homework, so long as it is in the manner of a library reference desk, ie. pointing you in the right direction. From the link by 209, you want reference 28, which I suppose is obvious since it is under the section "testing the hypothesis". The article is quite advanced, so try to pick up the gist. You may be interested in chaos theory, in particular Chaos theory#Distinguishing random from chaotic data. If the universe were a numerical simulation, there would presumably be limits on chaotic behaviour, since it involves intractable complexity. So your answer could propose ways of testing the universe based on subjecting chaotic processes to tests that determine if they are, in fact, truly chaotic. You will have to do this bit yourself. IBE (talk) 17:53, 28 December 2012 (UTC)

I'm curious what you think of these contributions (left-hand side) - http://en.wikipedia.org/w/index.php?title=Wikipedia:Reference_desk/Science&diff=prev&oldid=530148333 - the part that has been removed from the question. is it the same as what you propose? 178.48.114.143 (talk) 21:33, 28 December 2012 (UTC)

Very interesting, but I'll wait to see what someone smarter suggests. I think it's clear that we are dealing with a fairly bright person who hasn't got his ideas sorted out very clearly, or at least doesn't know how to express them. It is certainly along the same lines, however. IBE (talk) 21:43, 28 December 2012 (UTC)

I would also add that there are many possible configurations of the question itself - does it allow quantum computers, for example? It seems clear from the post you linked that the OP is not considering such possibilities, because quantum computers could definitely generate random numbers. If pseudorandom processes occurred in reality where science expects random ones, then yes, you have some hard evidence of a VM reality. Absence of them could indicate a quantum computer VM, however. I don't know how quantum computers might influence chaos calculations, but I would have thought not on a fundamental level. Please anyone who knows this stuff well, tell us about it. IBE (talk) 21:48, 28 December 2012 (UTC)

OP, have you read Stephen Wolfram's A New Kind of Science? It proposes that the universe is a just a very, very big cellular automaton. To tell if the universe is such a system could prove problematic of course, because if it's true then we are all part of it.. --hydrox (talk) 06:47, 29 December 2012 (UTC)

This question is very similar as the test for reality above. When I see such repetitions I get a feeling of deja-vu that let me thinking if the simulation we are immerse is saving in computational power by repeating stuff. OsmanRF34 (talk) 11:13, 29 December 2012 (UTC)

Ok, but this is much more empirical than the one above - just look at the difference in length of the discussions. Longer discussions here are usually traceable to unanswerable questions. Not that my own contribution here is any kind of exact answer - rather I was hoping to get someone to clarify/ refute my suggestions. IBE (talk) 15:06, 29 December 2012 (UTC)

I should note that if someone specifically wanted to rule out that that we are living in The Matrix, that is relatively straightforward. The rules of 'The Matrix' specify that the laws of physics and so on only apply as long as you expect them to, and that firm belief that (for example) you can jump really far or run really fast will allow you to do so. Put your hand up if you've ever 'missed a step' or taken an extra step when going up or down stairs. You were absolutely certain that your foot was going to move in a certain way, even support your weight where there was no step, and yet reality asserted itself and did not warp to match your expectations. Therefore, we cannot be in The Matrix.

All of which simply goes to show, as others have said, that in order to properly assess anything like this, you need to narrow down and be specific. Take and develop a theory of reality and work out how you would expect it to behave. Don't just go with vague general ideas. 86.129.14.69 (talk) 23:55, 29 December 2012 (UTC)

But "The Matrix" isn't quite what most "simulated universe" proponents are describing. In the movie, the human minds aren't "simulated" - they are actual humans. What I think we're discussing here is where our brains are also being simulated. You could test for being in a "Matrix" by looking carefully at (for example) brain scanners. You could perhaps make a sound in someone's ear - and look on the brain scanner to see when the neural pathways "lit up" in response to the sound. There would have to be a substantial delay between sound and response if the simulated sound had to travel along miles of wiring into the real human's brain and back again to the simulation computer. Other tests like deliberately destroying a part of a living brain and seeing how it affected the victim would also exhibit strange resuls in the matrix that would be completely different compared to (for example) animal brains. When you think about the level of scientific research amongst people in the matrix - it's rather surprising that they wouldn't have figured it out yet! However, in a "fully simulated" universe, there would be no such artifacts visible...so you couldn't prove a thing. SteveBaker (talk) 04:18, 31 December 2012 (UTC)

See this and this. Shadowjams (talk) 00:46, 30 December 2012 (UTC)

The trouble with both of those links is that they both assume that simulation has to happen in fixed time steps in a regular lattice. That's a naive view of how computer simulations work. We can do event-driven simulation where there are no fixed time steps - and we can do simulation in a continuum rather than a lattice and easily bypass the mechanisms that those articles rely on for their testing. Certainly most simulations aren't done that way for efficiency reasons - but there is no proof possible by showing the lack of a "grid" or a "time step" in our universe. SteveBaker (talk) 04:03, 31 December 2012 (UTC)

The point that most people who think about this forget is that the laws of physics in the "parent" universe (where the computer that's simulating us resides) don't have to be identical (or even remotely similar) to the laws of physics inside the simulation. Our computers are limited in speed by the speed of light - in power by the ability to dissipate heat - in size by the sizes of atoms and the nature of quantum mechanics - and the scale of a gigantic computer is limited by resources of the planet earth and our human ability to mass-produce parts.

Consider this: If our "parent" universe had no speed of light limitation, didn't even have things like atoms as fundamental particles - then computers could be made of logic elements billions of times smaller and trillions of times faster than ours - and be assembled into vast computers that could be trillions of lightyears across (remember - no speed of light limitations in the parent universe!)...in such a crazy place, it might easily be possible to simulate every last detail of every particle in our universe to precisions far higher than we can (even fundamentally) measure - and it could do it on a machine as commonplace (to them) as laptop is to us. Once you unshackle your thinking from the parent universe being in any way like ours - then all bets are off.

The "universes" that we make simulations of (computer games, for example) have plenty of restrictions that our universe doesn't have - in computer games, there are no full-spectrum colors - an inhabitant of the "Grand Theft Auto" universe (assuming his AI software would permit such a thing) would be able to take a spectrogram of the color of any object in his universe and discover that color is made up of a mixture of three distinct frequencies - Red, Green and Blue. He might formulate a complicate "physics" to explain this - and he'd imagine that anyone who was simulating him would have the same restriction. Well, guess what, the "parent" universe of the Grand Theft Auto universe has full-spectrum colors. Ha! SteveBaker (talk) 04:03, 31 December 2012 (UTC)

A drug meant specifically to induce pain

There are plenty of drugs to create a recreational experience, but are there any drugs that cause acute pain after injecting, swallowing or inhaling them?

I was wondering if such drugs could be used to turn recreational drug use into a painful experience via classical conditioning, by mixing the original drug with the pain-inducing one and giving it to the users. (Just to be clear, I didn't ignore the serious disadvantages, and possibly illegality, of this method, and don't expect to see it being applied to rehabilitate drug addicts.)

Thanks, 82.166.216.211 (talk) 23:49, 28 December 2012 (UTC)

Well, there are lots of drugs that cause pain upon being injected; I'm thinking that the vast majority of things you could possibly push into your bloodstream would probably hurt quite a bit. The problem is that drug dealers don't typically try to rehabilitate their users. I also doubt it would work, even if you got by the staggering legal and logistical hurdles. If watching yourself waste away, spitting out all your teeth, and slipping into the occasional coma don't do smarten people up, I'm not sure what will. :( Matt Deres (talk) 00:27, 29 December 2012 (UTC)

Because acute pain is more persuasive than those other things. That's why torture became so popular. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 06:57, 29 December 2012 (UTC)

That's pretty much the way Disulfiram (Antabuse) works in the treatment of chronic alcoholism. Tonywalton ^Talk 00:35, 29 December 2012 (UTC)

(e/c)You may find this interesting. Not quite what you were looking for, but very similar. Matt Deres (talk) 00:37, 29 December 2012 (UTC)

Ooh! Spooky! Tonywalton ^Talk 00:38, 29 December 2012 (UTC)

Platypus venom would be a wonderful candidate for the drug you seek.--Digrpat (talk) 00:46, 29 December 2012 (UTC)

This has been in the news, see the sadistic suggestions made about oxycontin and capsaicin. μηδείς (talk) 03:54, 29 December 2012 (UTC)

See poison. If they cause pain, they never get as far as being called drugs, which by definition are intended to have a beneficial or enjoyable effect. Most household chemicals don't get to be called drugs for that reason, but many of them will cause pain.--Shantavira|^{feed me} 12:20, 29 December 2012 (UTC)

Actually, a drug can be something that primarily or as a side effect causes an adverse effect. A common lay use is to indicate an adverse effect, as in "He gave the victim a stupifying drug and then raped her". As far as scientific or medical use goes, we were taught in 1st year university the following: A nutrient is a substance that enables body metabolism; the effect of nutrients is made apparent when they are absent. In contrast, a drug is a substance that affects body metabolism; the effect of drugs is seen in their addition. In other words, you can't do without nutrients - but you can do without drugs.

In the hospital/asylum treatment of severe mental disease, various forms of treatment have been used over the years to stimulate correct behaviour by "treatments" that cause pain or distress. In general, such treatments may be dressed up or genuinely thought to have some beneficial effect. A well known (non drug) example is electro-convulsive shock therapy (now discredited but replaced by magnetic induction therapy - the same thing slightly disguised). Clozapine and similar drugs, which are thought to reduce schizophenia symptoms, get used by the less ethical practitioners to cause pain or distress which may cause patients (not necessarily schizo patients) to suppress their undesirable, difficult, or non-co-operative behavior in order to avoid getting it again. In strong enough doses it causes pain, from intestinal and heart infarction, which is pretty scary, and distress from uncontrolled slobering and other problems.

When I was working (as avolunteer) at a drug adict support center, we would sometimes get folk presenting themselves and claiming they were addicted to heroin when they were not (it was one way to get methodone for a friend or to sell - there were other more bizare reasons). What the doctor did was give them an injectable narcotic agonist. If the person had not been on the claimed drug, the agonist would have little or no observable effect, and they would be told to nick off. But if the person was actually consuming heroin (or whichever), they would go into immediate full on withdrawal symptoms - pain, shakes, shock, etc, for a short time. Then we knew they were genuine, and needed our help.

It would be very difficult to cure hard addicts of their addiction by classical conditioning. Severe pain may be the least of their problems (Whoop Whoop is quite incorrect in this); you can be as high as kite while in severe pain and not mind the pain; in any case narcotics suppress pain.

Floda 58.170.169.255 (talk) 16:15, 29 December 2012 (UTC)