Wikipedia:Reference desk/Archives/Science/2011 May 30

= May 30 =

Underwater vehicles
If I have sapients who live underwater, would a water-powered vehicle with a driver, looking sort of like a submarine but filled with water, be of any use in getting the passengers places without requiring them to move about consciously? Would they be able to swim just by sitting pasively in the water, or does an underwater creature have to use energy to swim? I want to know if my underwater people could have any use for a plastic vehicle. Subliminable (talk) 00:17, 30 May 2011 (UTC)
 * Yes, an underwater creature does have to use energy to swim - the alternative is to fasten yourself to a rock and wait for your food to float towards you (sessile is the technical term), or float where the currents or tides take you, neither of which is a good start for developing intelligence. _Powering_ the underwater car might be a bit tricky - it can't be water-powered, it'll need some other energy source, and your people won't have fire.  Clockwork, perhaps? Tevildo (talk) 00:40, 30 May 2011 (UTC)
 * I'm not sure that the idea of an enclosed car is all that useful underwater, given the amount of added resistance from any large vehicle. On the other hand, I'd think that for underwater dwellers, any method of creating a smooth, slippery tube should be quite useful - a simple device to raise water level higher at one end and release it abruptly should produce a means of propulsion at speeds unattainable in the ocean proper.  Or a cable set in an area crossing a strong current might allow people to quickly cross at an angle to it by holding onto something akin to a zipline.  I'd think that a civilization armed with a method to create plastic-like biopolymers, a good set of tidal power technologies, and a good map of the ocean currents should be able to come up with very useful transportation technologies even in the absence of fire and metal.  Supplementing plastic scaffolds with robust constructions from stone, clay, or other minerals, geothermal power from mid-ocean ridges and black smokers (perhaps, in time, even some low temperature metal smelting) might add useful tools to this. Wnt (talk) 03:56, 30 May 2011 (UTC)
 * I'm not sure what "Water powered" means in this context. For a variety of reasons, no society will ever use water as fuel. "Water powered" usually refers to water-wheels on dams and stuff.  I'm not sure how a vehicle could be "Water powered" unless you just mean a boat that drifts downstream.
 * If your merpeople have the technology to build engines, then a DPV would probably be the equivalent of a motorcycle, to them. It might even be possible to make one out of clockwork.
 * If you're imagining a modern sport submarine accidentally being lost to the depths and salvaged by merpeople, I'm not sure how useful they'd find it. Very few sport submarines could travel faster than one would reasonably expect a mermaid to swim, perhaps none.  They're not good for long-distance either, though I suppose if you took out the air-tanks and put in larger batteries maybe they'd be useful for that.
 * If I were a merperson who needed to get somewhere quickly, and had access to a plastic craft. I would consider making a surface boat that could be filled with enough water for me to breath. A surface sailboat would certainly be useful for a merperson. On a windy day it would go much faster and farther anything can swim. APL (talk) 05:53, 30 May 2011 (UTC)
 * Where do baby merpersons come from? What's the difference between a merman and a mermaid, and why? Cuddlyable3 (talk) 11:10, 30 May 2011 (UTC)
 * Mermen have smaller breasts and never were bikini tops Nil Einne (talk) 13:40, 30 May 2011 (UTC)
 * ...nor wear them. Cuddlyable3 (talk) 20:22, 30 May 2011 (UTC)

Actually your vehicle designed to deliver occupants who are themselves submerged in water already exists. A sort of open topped submarine so to speak. cf: SEAL Delivery Vehicle Hcobb (talk) 18:20, 30 May 2011 (UTC)
 * Human torpedoes have been in use since at least WW2. 92.24.191.98 (talk) 23:13, 30 May 2011 (UTC)
 * If nothing else, a vehicle would be useful to merpeople as a way of hauling cargo. Even if it went slower than they could swim on their own. If you needed to haul a load of clam-shells to the bikini factory, a sub would be a heck of a lot easier than trying to drag them around in giant sacks. APL (talk) 20:45, 30 May 2011 (UTC)

You might want to read Surface Tension by James Blish Greglocock (talk) 05:03, 31 May 2011 (UTC)
 * Yes. That is a tremendous story. APL (talk) 06:08, 31 May 2011 (UTC)

combination of solar wind
which elements and particles are there in combination of solar wind?--78.38.28.3 (talk) 09:07, 30 May 2011 (UTC) iran may 2011
 * Our article Solar wind may be useful. It says mainly electrons and protons. --Colapeninsula (talk) 09:22, 30 May 2011 (UTC)

If some particles such as alpha ray and electron accelerate in solarmagnetic field that might other particles such as carbon and nitrogen and oxygen be accelerated too. my main aim of this question is this :is there any other particles observed in combination of solar wind? a. mohammadzade--78.38.28.3 (talk) 05:25, 31 May 2011 (UTC)  — Preceding unsigned comment added by 78.38.28.3 (talk) 05:22, 31 May 2011 (UTC)


 * Solar wind contains tiny, tiny, incredibly trace quantities of heavy elements. Stellar nucleosynthesis explains how heavy elements are created in the sun; our coronal mass ejection hints that in such eruptions (where the density and quantity of ejecta is much larger than the steady-state solar wind), scientists can see spectra from heavier elements.  This paper from Solar Physics in 1993, Material Ejection, reviews several standard techniques for measuring the contents and the types of particles emitted from our Sun in various different types of ejections.  Nimur (talk) 16:18, 31 May 2011 (UTC)

Brains of superorganisms
Does a colony of ants considered as a superorganism have a brain? Count Iblis (talk) 16:18, 30 May 2011 (UTC)


 * Yes, thousands of them. If you aren't satisfied with that answer, please clarify what you are trying to figure out.  It seems likely that you already know all of the relevant facts. Looie496 (talk) 16:31, 30 May 2011 (UTC)


 * Yes; if you understand that the language of the 'superorganism' is patently metaphorical, then the 'decision-making' functions of a brain are handled via emergent behaviors of the colony, which arise from each ant's local interactions with their peers and environment. (e.g temperature and humidity regulation in a colony of leaf-cutter ants). SemanticMantis (talk) 17:55, 30 May 2011 (UTC)


 * The language of the superorganism is really not much more metaphorical than the language of the organism. An organism is a collection of closely cooperating cells that share a common genome; a superorganism is a collection of closely cooperating organisms that share strongly related (but usually not identical) genomes. Looie496 (talk) 18:01, 30 May 2011 (UTC)


 * There is a theory out there that says a superorganism has a superbrain, where each individual member acts like a pseudoneuron. Plasmic Physics (talk) 22:49, 30 May 2011 (UTC)


 * Yes, that is what I mean. So, how sophisticated would such a superbrain of an ant nest be? Count Iblis (talk) 01:20, 31 May 2011 (UTC)


 * I'm not sure that I understand this notion of a superbrain in social insects. If it is more than a metaphor, what is it in fact ? I share my living space with a mature weaver ant (Oecophylla smaragdina) colony that is probably well on its way to reaching the upper limits of colony size for this species. It certainly has several hundred thousand major and minor workers spread over hundreds of nests. Other than an apparent intent to make life quite difficult for almost everything near it, what evidence would demonstrate the existence of an actual non-metaphorical "superbrain" ?  Sean.hoyland  - talk 03:12, 31 May 2011 (UTC)


 * I think ants lack some prerequisites for such a "super-brain":


 * 1) There needs to be a method to record individual thoughts, determine which are important to the colony, prioritize them, and then convey them only to the relevant members of the colony.


 * 2) There needs to be a way to convey such thoughts to subsequent generations.


 * As far as I can tell, the only animal to achieve this is humans, due to the invention of writing and, more recently, the Internet and globalization, and thus only we have a super-brain (meaning that collectively humanity knows far more than any individual alone knows). StuRat (talk) 04:53, 31 May 2011 (UTC)


 * An ant mill may be of interest when considering the intelligence of ants. I think it shows that there is no great overriding intelligence, but just culture with the same propensity for self-destructive trends as human culture.  But probably someone else would disagree.  Historically though, the idea of ants as a "super-organism" comes from their mode of reproduction, not their mode of thinking.  If the Nazis had won the war and started having designated genetically pure Mothers inseminated by a tiny number of Aryan Heroes, before long humans would be a "super-organism".  Not exactly a step forward though. Wnt (talk) 19:22, 31 May 2011 (UTC)

Any garden flower with leaves that look like a thistle?
Is there any garden flower whose leaves look like a thistle? I have a thistle-like plant two or three feet high that has appeared in an old flower bed in the UK. It has dark green leaves, and has not flowerd yet, whatever it is. It might be some flower seed that has germinated, or it may be just a large thistle. 92.24.133.185 (talk) 16:40, 30 May 2011 (UTC)


 * Take a look at this poppy. Argemone mexicana. I don't know what size it gets but it looks like thistle to me.  Wanderer57 (talk) 17:06, 30 May 2011 (UTC)


 * another picture of the same species
 * http://www.natureproducts.net/Forest_Products/Ornamentals/Argemone%20mexicana%201.300.jpg Wanderer57 (talk) 17:08, 30 May 2011 (UTC)


 * There's a chance it could be an ornamental, but I think better odds are on thistle. Thistles are amazingly aggressive plants. Several European species are highly invasive in the rest of the word, such as Carduus acanthoides and Carduus nutans. Even though native to the UK, the Cursed_Thistle is listed as an "injurious weed" in the United Kingdom under the Weeds Act 1959. Many (most?) thistles could quickly swamp the entire bed and become very painful/tedious to remove. SemanticMantis (talk) 17:46, 30 May 2011 (UTC)


 * It might be one of the many varieties of Eryngium, for example, a fairly common garden plant that readily self-seeds. Richard Avery (talk) 07:11, 31 May 2011 (UTC)


 * There has been a fashion in the UK amongst garden designers to include thistles, mainly of the Cirsium variety, in their designs. I would say, unless you can upload a picture of the plant when it flowers, we're not going to be able to really help you. --TammyMoet (talk) 09:32, 31 May 2011 (UTC)

Why is quantum mechanics so packed with relativistic corrections?
Why have things like Thomas precession glued onto the side of quantum mechanics? Why not drop string theory etc. and focus on getting a model of the atom that actually works from first principles? Do we still not have enough computing power to solve these basic problems? The nanotech payoff from understanding how atoms really interact would be huge. Hcobb (talk) 18:29, 30 May 2011 (UTC)
 * These aren't the kind of problems that can be solved by just throwing lots of computer power at them. String theory is an attempt at coming up with a theory that, among other things, accurately explains atoms. The problem we have at the moment is that neither quantum mechanics or general relativity correctly explain atoms. It seems we need both of them, but they are difficult to combine which is why we end up with rather unconvincing corrections instead of a single set of first principles from which the behaviour of atoms can be derived. String theory is the current favourite such set of first principles, although it's far from fully worked out. --Tango (talk) 21:00, 30 May 2011 (UTC)
 * I don't think that's right. A working theory of quantum gravity would be needed for dealing with extremely high energies (at the Planck scale), or for dealing with spacetime right near the Big Bang or near the singularity at the center of a black hole, and it would be good for dealing with Hawking radiation with more confidence, but it isn't needed for a normal quantum mechanical treatment of atoms.  Special relativity is needed, because the inner electrons of large atoms move at relativistic speeds (as do the nucleons, if you want to include a detailed modeling of the nucleus), but general relativity isn't needed, because gravity is normally negligible compared to the other forces when dealing with atoms, i.e., in most cases of interest, atoms normally exist within a spacetime that's so close to flat that any general relativistic corrections would be negligible compared to other errors that occur in computational quantum mechanics.  Red Act (talk) 22:56, 30 May 2011 (UTC)
 * It's not clear to me what you are complaining about. Thomas precession is a real effect and we already have a model for it that works. There are already, as we "speak", people working on developing accurate computer models that calculate energy levels of atoms including relativistic effects. It's also not clear how dropping string theory would help solve such problems. Dauto (talk) 21:14, 30 May 2011 (UTC)


 * Some thoughts:
 * Undergraduate quantum mechanics is nonrelativistic, but quantum field theory is (special-)relativistic; Thomas precession is built into it, not added on.
 * We don't have enough computing power to solve these problems, and we never will. Quantum theories as presently defined can't be solved by brute force even in principle, because they model spacetime as a continuum. Better approximation techniques are the only way forward. Even if the standard model is supplanted by a completely finite model, doing interesting exact calculations in that model would be harder than brute-forcing an AES-256 key, which is to say that it would be impossible. It's not the case that with Moore's law all things are possible.
 * We don't know the real laws of physics, so it's debatable whether the "exact" theories we're approximating are any more accurate than the "approximations". In fact, the "exact" standard model has never been given a rigorous mathematical formulation and probably doesn't exist as a mathematical object. The standard model apparently resembles the correct theory inasmuch as it's a useful guide to the development of approximate calculational methods, but the calculations work because they approximate the real physics, not because they approximate the standard model, which doesn't even exist.
 * String theory research has led to useful new methods of doing (approximate) calculations in quantum field theory in cases where traditional perturbation theory (Feynman diagrams) is useless.
 * We would benefit from a better understanding of atomic-scale physics (we would benefit from a faster way of solving the protein folding problem, for example), but this is not at all the same as modeling the atom from first principles—just as understanding turbulent flow is not the same as deriving the Navier–Stokes equations.
 * -- BenRG (talk) 23:20, 30 May 2011 (UTC)


 * I think an underlying motivation may be the belief that the right theory may be intrinsically beautiful. This idea dates back at least to the radio term in Maxwell's equations.  If relativistic quantum theory is the true theory, one may expect it to be "elegant" in form.  Of course, that is not really a scientific argument - nonetheless, an interesting one. Wnt (talk) 23:07, 31 May 2011 (UTC)

how to say "brain" (brain of the skull) in greek \ latin? and should we say BRAINOLOGY?

 * cerebrum -i n. the brain; the understanding; hot temper. Cuddlyable3 (talk) 20:11, 30 May 2011 (UTC)
 * The study of the brain and nervous system is called neuroscience. "BRAINOLOGY" is not an English word. Cuddlyable3 (talk) 20:14, 30 May 2011 (UTC)
 * εγκέφαλος, μυαλό Cuddlyable3 (talk) 20:17, 30 May 2011 (UTC)
 * And the greek version, that Cuddlyable3 provided, would in the latin alphabet be rendered "encephalos" (alternatively "encephalon"), used in words such as encephalitis, electroencephalogram etc. The study of diseases of the brain and nervous system is called neurology. --NorwegianBluetalk 21:29, 30 May 2011 (UTC)

Hello, is there another literaturic word for the Brain of the skull?,

thanks. — Preceding unsigned comment added by 79.183.27.165 (talk) 08:29, 31 May 2011 (UTC)

Skeletal System    ..
Hi everybody

Bones covered with special tissue  is  called ? 184.163.238.18 (talk) 20:39, 30 May 2011 (UTC)_ __
 * Periosteum? What do you mean by "special"? Tevildo (talk) 20:51, 30 May 2011 (UTC)