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March 2

Solving a simplified 1-D time-independent Schrodinger-esque equation

I've been trying to solve the following equation numerically using a Python program that I've written. It works reasonably well, but not perfectly. I'm under the impression that it can be solved exactly using analytical methods and I was wondering if anybody would be able to point me in the right direction. Unfortunately, my maths and physics knowledge is very limited, so I can't guarantee I'll have a clue what you are talking about.
${\frac {d^{2}A}{dR^{2}}}={\frac {-8\pi ^{2}m}{h^{2}}}\left(E-\left(-{\frac {e^{2}}{4\pi \epsilon _{0}R}}\right)\right)A$, where m = mass of electron, h = Planck's constant, E = energy of first level in hydrogen atom, e = charge on an electron, $\epsilon _{0}$ = permittivity of free space, R = distance between nucleus and electron, A = amplitude of resulting wavefunction. Thanks --80.229.152.246 (talk) 00:04, 2 March 2010 (UTC)

See: Hydrogen_atom#Wavefunction, specifically the n = 1, j = 0, m = 0 case. Dragons flight (talk) 00:48, 2 March 2010 (UTC)

Yeah, I've looked at stuff like that before and I'm afraid it's slightly above my head. Any suggestions as to where I should start to try and learn some of the stuff? --80.229.152.246 (talk) 15:32, 3 March 2010 (UTC)

Long legged wasps

Over the last 15 years I've noticed the normal wasp being replaced by a longer legged more aggressive variety in the Pyrénées-Orientales in France. I can't seem to find it in the list of common wasp species on the wasp article, does anyone know what this wasp is? Is it another species or just a variant, it seems pretty different. As far as I can tell it's a paper wasp but the article says that they're less aggressive, not more, and also doesn't mention the fact that the yellow jackets are becoming less common compared to the paper wasps. 82.132.136.206 (talk) 00:31, 2 March 2010 (UTC)

Coreinae - Insect families/tribes

This page lists 10 tribes, Wikispecies lists a lot more than 10 tribes on it's Coreinae page ... which is correct? Should the extras from wikispecies be in the wikipedia article aswell? I'm asking because I was about to make a stub for Amorbini... Thanks. Benjamint 01:36, 2 March 2010 (UTC)

Coreinae page gives the tribes list from ITIS 2006 record, here. You can use it. However, those things tend to change every once in a while, as more studies are carried out; so don't be surprised if the tribe list changes in a couple of years. --Dr Dima (talk) 06:41, 2 March 2010 (UTC)

OK, so wikispecies is more up to date? Should I amend the wp page with the wikispecies list? I think I'm out of my depth so maybe I should just leave it. Benjamint 08:15, 2 March 2010 (UTC)

If the Wikispecies list is reliably sourced, by all means bring the WP page up to it; but you can't use Wikispecies as a reference in WP. --ColinFine (talk) 21:42, 2 March 2010 (UTC)

Speckled Bear vs. Spectacled Bear

Are the Speckled Bear and Spectacled Bear different species?

Searches on Google yield conflicting results; Wikipedia doesn't, have an article, or any reference to, a "Speckled Bear." Each name is used individually on multiple websites; but I haven't any one source that acknowledges the use of two similar, yet distinct names... let alone the resulting confusion/misinformation. Results from Google image searches are different enough that they could be of separate species, but similar enough that they could simply represent variation within one species. Aside from Wikipedia's "Spectacled Bear" article, none of the sources I've encountered offer much in the way of verification/credibility, so I figured I'd ask for feedback here.

Ajburket (talk) 02:21, 2 March 2010 (UTC)

There is no speckled bear. See our Bear article which lists all eight surviving species. Rmhermen (talk) 02:46, 2 March 2010 (UTC)

There are several videos[1] [2] [3] at YouTube with "speckled bear" in their titles. This seems to be just a misnaming of Spectacled bears by zoo visitors. Cuddlyable3 (talk) 19:11, 2 March 2010 (UTC)

magnetic field

Would a magnetic field generated around a space ship or space station protect it from radiation, particles or anything else or just make radio transmission more difficult. 71.100.5.197 (talk) 02:49, 2 March 2010 (UTC)

Yes, it is one option that has been considered. Here is one reference that discusses it: [4]. --Tango (talk) 03:57, 2 March 2010 (UTC)

The Maxwell equations are linear, therefore a static magnetic field does not make radio transmission more difficult. —Preceding unsigned comment added by 83.134.160.138 (talk) 06:41, 2 March 2010 (UTC)

It would protect the ship from alpha particles, beta particles and proton radiation, but not from neutrons or gamma rays. Clear skies to you 24.23.197.43 (talk) 07:04, 2 March 2010 (UTC)

Cosmic rays are almost all charged particles, so we're ok. --Tango (talk) 07:06, 2 March 2010 (UTC)

A magnetic field wouldn't have much affect on large particles unless thay were ferrous would it? And then wouldn't it tend to attract them? (I'm not thinking of sub-atomic here as above, tell me if I'm wrong!) These may be of interest Scientists Designing "Ion Shield" To Protect Astronauts From Solar Windsourced from Sun shield to let space crews boldly go to Mars and Spacecraft Shielding —220.101.28.25 (talk) 17:06, 2 March 2010 (UTC)

Ferrousness (is that a word?) applies only to lattices of atoms, we're talking about individual particles. The key concept here is whether they are charged or not. A charged particle (electrons, protons and alpha particles, primarily) travelling through a magnetic field will be deflected. --Tango (talk) 18:22, 2 March 2010 (UTC)

Ferocity ? :-) StuRat (talk) 18:42, 3 March 2010 (UTC)

I wonder how powerful a magnetic field should be to deflect protons coming at relativistic speeds. The LHC article says dipole magnets at the field strength of 8.3 teslas keep 7 TeV proton beams in their orbit. As some cosmic particles are much more energetic than man-made ones, is it feasible to maintain such a field for long durations, in a small spaceship? 88.242.228.248 (talk) 17:56, 2 March 2010 (UTC)

Change Simulink Algebric Loop Solver Props

I have a simulink model consisting of feedbacks. After a few iterations, simulink shows up a "cannot solve algebric loop" error for a block. I noticed that for that time instant (0.24), it had already found out converging values of the block (within my accuracy requirments). How do I modify its algebric loop solver configuration ? —Preceding unsigned comment added by 218.248.80.62 (talk) 08:01, 2 March 2010 (UTC)

I'm not familiar with that software, but I suspect it must have some setting for how many iterations to try before giving up. If not, you could manually copy the results from one run as the starting conditions for another run, and thus get a better result (assuming it is a converging case). Also, you might try the Math Desk. StuRat (talk) 18:39, 3 March 2010 (UTC)

plasma

does plasma take an indefinite article, (such as 'a lake') or not (such 'as water'). The article was inconclusive. —Preceding unsigned comment added by 129.67.116.170 (talk) 18:05, 2 March 2010 (UTC)

It depends on context. Is there a particular sentence you are wondering about? --Tango (talk) 18:25, 2 March 2010 (UTC)

... like soup! Dbfirs 19:02, 2 March 2010 (UTC)

Or, indeed, like "solid", "liquid", and "gas". ("The bottle contains 200 cc of liquid"; "The bottle contains a liquid") Probably a question that's better for the language desk; see mass noun. Tevildo (talk) 19:27, 2 March 2010 (UTC)

No it doesn't -- you can't say "a plasma", it would be wrong. The only exception is if you specify a particular type of plasma (e.g. you could say "a xenon plasma"). 24.23.197.43 (talk) 05:06, 3 March 2010 (UTC)

You (or at least I) might say "when heated, the material formed a plasma", or some other construction. I agree that it depends on the context, just as other states of matter do. Buddy431 (talk) 06:31, 3 March 2010 (UTC)

Yeah, 24.23.297.43 is wrong. There's nothing about plasma that forbids taking an indefinite article. In fact it's (much) easier to find correct, natural sentences that include a plasma than it is to find ones that include a water. But even a water is possible in the right context. --Trovatore (talk) 19:27, 3 March 2010 (UTC)

Male and female human voices

It's an easily observable, almost universal, fact that almost all female humans have higher-pitched voices than male humans. This is already noticeable with children, but even more so with adults. Most people accept this as natural and don't think twice about it. But what exactly causes it? JIP | Talk 20:04, 2 March 2010 (UTC)

Puberty#Voice change has some information about the mechanism of it. I don't know what, if any, evolutionary benefit it has. --Tango (talk) 20:16, 2 March 2010 (UTC)

Human voice may also be of interest to you. Vimescarrot (talk) 20:17, 2 March 2010 (UTC)

I imagine that sexual selection is at play here. Different pitches are a sexual characteristic magnified by puberty, I think. Imagine Reason (talk) 15:41, 3 March 2010 (UTC)

Super-fast spaceship

Wouldn't it be in practice impossible to have extremely fast space ships such as you'd need to get humans to other stars, because they would go so fast that the tiniest specks of space-dust would go through them like bullets and cause lots of damage? —Preceding unsigned comment added by 84.13.29.241 (talk) 21:41, 2 March 2010 (UTC)

Yes, relativistic effects can make the interstellar medium deadly. You'd need some sort of shielding mechanism to counteract it. — Lomn 21:50, 2 March 2010 (UTC)

Then there is also the practical problem of being able to accelerate your spacecraft at about 1g for a full year, and having a full year of fuel to decelerate once you arrive (well a year before). Googlemeister (talk) 21:55, 2 March 2010 (UTC)

There are possible methods. The acceleration can be done by pushing the ship along with a laser beam from Earth if you can't take enough fuel with you. There are ways of slowing a ship down the same way, but you would be so much further away that it would be hard - a laser could be sent in advance as part of an unmanned probe that can take decades to arrive without it being a problem. --Tango (talk) 00:09, 3 March 2010 (UTC)

The Bussard ramjet is an idea for using the interstellar medium as fusion fuel on your spaceship. In practice, "go slow" is our only recourse. --Sean 22:01, 2 March 2010 (UTC)

It is unclear if a Bussard ramjet could actually generate more thrust than drag. --Tango (talk) 00:09, 3 March 2010 (UTC)

Only as impossible as a deflector dish! TastyCakes (talk) 22:59, 2 March 2010 (UTC)

The shielding could be done, the real question is whether it can be done without adding so much weight that the ship is impossible to accelerate. --Tango (talk) 00:09, 3 March 2010 (UTC)

Here's my approach:

1) Start with a spaceship which is a massive linear particle accelerator, using matter/anti-matter engines with tanks full of anti-matter in a magnetic containment "bottle".

2) Go to the asteroid belt and clamp onto a huge asteroid.

3) The ship will then slowly mine the asteroid, which is positioned in front of the ship to act as a shield.

4) A particle stream (consisting of particles mined from the asteroid) zips out of the linear accelerator at the speed of light, driving the ship ("be careful where you point that thing !", the Sun might be a good choice).

5) When the ship nears it's destination, a hole is drilled through the asteroid, and the particle accelerator is reversed to send particles through the hole at the speed of light. Alternatively, the ship can be turned 180 degrees. The particle stream will act as a shield to prevent dust particles from getting to the ship during decel. There will be a short period of vulnerability while the reversal occurs. It may be possible to scan for approaching dust particles and time the reversal for a clear period, or they may just have to take their chances.

6) When the ship stops, discard whatever remains of the pitted and hollowed-out asteroid and pick up a new asteroid for the trip home (you might want to make sure the target system has asteroids before you set out). You should have a good 5 minute period before the kids return to asking "Are we there, yet ?".

Such a design might be able to do maybe 10% of the speed of light, so it might take some 45 years to reach the nearest stars. Unless you freeze the people, they likely would die during the return trip. So, I'd either have them stay there or do the whole thing robotically, and don't worry about a return trip. StuRat (talk) 15:49, 3 March 2010 (UTC)

That's all great except for the "matter/anti-matter engines" bit. We have absolutely no idea how to generate antimatter in such a way as to get positive net energy. Oh, and the dust is pretty constant (although very low density), so you aren't likely to find any gaps. If you put the sensitive stuff in the middle of the asteroid, it won't matter which way it is facing. I can't see how a particle stream would act as a shield, though, the density of the stream wouldn't be high enough to stand a good chance of intersecting much of the dust. --Tango (talk) 04:44, 4 March 2010 (UTC)

The antimatter wouldn't be generated on board, but would be created and placed on the ship prior to launch, similar to how rocket fuel is loaded now. The energy source used to produce the antimatter at the launch base might be a series of nuclear reactors (hopefully fusion). I like the idea of putting the ship completely inside the asteroid. I'm hopeful that the matter stream could be kept narrow and at a high density, at least a small distance ahead of the ship. Remember, it only has to protect the hole from which the matter stream flows, while the asteroid will protect the rest of the ship. StuRat (talk) 15:35, 4 March 2010 (UTC)

Are chickens intelligent enough to suffer?

This afternoon I was faced with the dilemma of buying six free-range eggs for £1 or ten battery-hen eggs for 78p. Are tiny-brained chickens intelligent enough to suffer in a battery cage, or realise that they are missing out on going free-range? Are they smart enough to have any conciousness at all, or have any sense of self? I did buy the free-range eggs. Thanks. 84.13.29.241 (talk) 22:02, 2 March 2010 (UTC)

There is, in principle, no way to know anything for sure about the qualia of chickens (or, for that matter, any being other than yourself). But to me it seems very likely that they are capable of suffering. I also prefer to buy cage-free eggs. --Trovatore (talk) 22:10, 2 March 2010 (UTC)

Unfortunately I think "cage-free" is likely to mean hens that spend all their lives in pernament darkness or almost-darkness in a large modern barn while packed in shoulder-to-shoulder with a sea of other chickens. 84.13.29.241 (talk) 22:18, 2 March 2010 (UTC)

Having raised chickens in my youth, being a free range chicken would not be all fun and games either. Chickens can be quite brutal to each other. Googlemeister (talk) 22:15, 2 March 2010 (UTC)

Though this may not answer your direct question, I'm sure you'd be interested to know that there is literally no (US) federally mandated standards with which a chicken/egg/ect. producer needs to meet in order to call their product "free range". In every meaningful sense it means nothing besides it being a fantastically effective marketing scheme. Chris M. (talk) 22:20, 2 March 2010 (UTC)

This is a very complex issue and my personal jury is still out on the subject. Unfortunately one of the main factors to consider is that "free range" is not very well regulated in the US or Australia, I'm not sure about the UK, but I'd be surprised if it was much different. This means that there is actually no "standard" that a producer has to follow to label their product "free range" and "some" free range labelled eggs come from very similar conditions to battery eggs, except maybe they have a "window" or something equally as superfluous. In Australia we have brands which are RSPCA certified free range eggs which I believe is well monitored and enforced but there are other eggs labelled "free range" which are not as enforced. That doesn't actually answer your question. Yes chickens are stupid but I just can't see how that gives us a right to exploit and abuse them to the fullest possible extent for our benefit. Chickens are easily the worst abused animals we farm, just google clips of battery hen condition, and don't do it with kids around, it's like a horror movie. Or maybe don't if you don't have a strong resolve and don't want to be a vegetarian. ;) Vespine (talk) 22:24, 2 March 2010 (UTC)

There are regulations for free-range in the EU, see Free-range eggs. Four square meters per hen for "free-range". ten square meters per hen for "organic free range". However the current photo in that article does not look like free-range to me, but barn-hens. The free-range commerical hens I've seen from the roadside here in the UK were similar to this http://www.youtube.com/watch?v=gS78WhX2ubY and could have been organic-free-range. 84.13.29.241 (talk) 22:37, 2 March 2010 (UTC)

Part of this requires a definition of suffering. They certainly feel pain. They certainly feel stress. They certainly have some type of consciousness, though they don't appear to be sentient. (I say "certainly" in these instances to mean, "within a reasonable physiological definition," not to indicate I know what chicken qualia is like.) They probably don't know they are "missing out" (but then again, a human raised exclusively in such conditions would probably not know they were "missing out" on a wide world of options, either). Is a sense of self required for suffering? --Mr.98 (talk) 22:29, 2 March 2010 (UTC)

I belive the term you're looking for is sapience (when you say a chicken doesn't have it). the sentience/sapience confusion is remarkably common. Chris M. (talk) 15:03, 3 March 2010 (UTC)

I would note here that sentient means "capable of feeling", not "capable of thinking". I don't know what you mean by saying they have consciousness but are not sentient. --Trovatore (talk) 00:52, 3 March 2010 (UTC)

Hmm, I meant in the sense used at Sentience: "the ability to feel or perceive subjectively". Apparently the term has a number of meanings depending on the field it is being used, though. The article itself brings up some useful points for thinking about it. --Mr.98 (talk) 00:57, 3 March 2010 (UTC)

If you don't have subjective experience, in what sense can you be said to be conscious? --Trovatore (talk) 01:11, 3 March 2010 (UTC)

I think you probably need a concept of emotion - do chickens feel happiness and sadness? I'm not sure we'll ever really know... --Tango (talk) 00:13, 3 March 2010 (UTC)

Here's an interesting quote from Cecil Adam's treatment[5] of the subject : "UK researchers studying commercial poultry farms say only 15 percent of chickens who have the opportunity ever leave the henhouse." APL (talk) 00:37, 3 March 2010 (UTC)

This video seems somewhat informative. Bus stop (talk) 00:54, 3 March 2010 (UTC)

Please understand that regulations and conventions are different in different parts of the world even in english speaking countries. The regulations for "free range" seem more hen-friendly in the EU than they are in the US - see above. 78.151.146.204 (talk) 01:09, 3 March 2010 (UTC)

Is opposition to suffering, as such, morally correct, and if so why? ...Is a question you might ask next. 213.122.45.10 (talk) 02:05, 3 March 2010 (UTC)

A chicken will undoubtably experience everything that you yourself would experience if you were put in its position. the only real difference between animals and humans (cognitively speaking) is that humans are capable of a high level of abstraction: You can sit in a cage and imagine all sorts of alternate situations (how you might escape, what you'll do if you get out, whether or not being stuck in a cage is justified, how you might pass the time each day). Chickens can't - they are simple stuck experiencing whatever it is they experience while stuck in the cage. I don't know if that's more misery or less misery, but I think you can judge by the fact that most chickens would run away from a cage if they could that it's probably not a lot of fun. --Ludwigs2 02:17, 3 March 2010 (UTC)

I've thought a lot about these sorts of issues, and in my opinion that only sensible approach is to look for signs of distress. Do the chickens fail to care for themselves, or peck at themselves, or make attempts at escaping, or squawk, or otherwise fail to thrive? I don't know the answer, but in my opinion any approach that isn't based on looking at behavior leads to answers that are purely based on preconceived beliefs. Looie496 (talk) 02:29, 3 March 2010 (UTC)

The assumption that brain size has anything to do with depth of feeling is a specious one. After all, Neanderthals had a much larger cranial capacity than extant humans. Did they have a richer experience of the world as a result? Who knows -- but I for one very much doubt it. SortedButter (talk) 03:09, 3 March 2010 (UTC)

Not sure what you mean by "depth" of feeling but, given that these feelings originate in the brain, I would expect that brain size is relevant. If a hypothetical animal had a tiny brain composed of 5 neurons, would you say that it is capable of suffering or feeling distressed at being locked up? Zain Ebrahim (talk) 08:10, 3 March 2010 (UTC)

Yes, but you cannot honestly say that a fly has a weak or negligible response to finding something sweet to eat, because it has only a tiny fraction of the 'brain cells' that a human has. Who knows how anything feels that is not you. SortedButter (talk) 13:34, 3 March 2010 (UTC)

• The field of animal cognition is a very interesting one and still a matter of considerable debate. It used to be that animals were considered automatons with no emotions, which reacted to stimuli. Some older scientists still hold onto this, but the depth of animal behaviour is slowly being explored. Alex (parrot) is a good place to start (although the article doesn't really examine the impact he had on the science in general... something I may have to rectify). While crows, parrots and tits are reckoned to be the brightest of birds, that doesn't mean that dumber birds are less capable of complexity and feeling. The extent to which humans can relate to the moods and lives of chickens is evident in how many chicken behaviours have influenced our own langauge. Sabine's Sunbird talk 03:43, 3 March 2010 (UTC)

You might also ask yourself whether you actually want to eat an egg that came from a chicken covered in feces, which breathes fecal dust its whole life, which must be fed antibiotics due to all the feces in its life, which in many cases is sharing a cage with a partially decayed hen that is left to rot through the wire floor, and on and on. I personally don't buy eggs unless they came from chickens I can actually see (friends with hens, etc.). The alternative is too repugnant, and not just morally. --Sean 16:38, 3 March 2010 (UTC)

In my youth we had hens who slept in a large henhouse, but ran around in a large fenced enclosure during the day, free to scratch for bugs, and free to flap their wings and fly a bit. Some of the birds could fly out and explore the woods, but came back for dinner. A pigeon also moved in and stayed for a couple of years, so that "free-range" setup was clearly preferable to some birds than "unlimited freedom." I cannot honestly say the eggs tasted any different from those I buy at the store which are "cage free" or eggs produced in typical abusive commercial operations. I just prefer to pay several times as much for the cage free ones. I certainly believe that birds can be happy or unhappy, calm or distressed, and that they can suffer. Edison (talk) 19:47, 3 March 2010 (UTC)

I have no direct experience, but from what I've been reading it seems that what is called "cage free" in the US is not the same as what we'd call "free range" in the UK. I fear that "cage free" in the US may simply mean that the chickens are kept all their lives in darkness in an enclosed barn packed with a huge crowd of other chickens, possibly de-beaked too. Nearly as bad as being in a cage. 89.243.73.49 (talk) 22:50, 3 March 2010 (UTC)

thermoelectric generators

It would seem like the relatively extreme difference in temperature of an object's surface that faces the sun and the surface that faces the stellar background would be ideal for generating electricity both from thermoelectric generators and closed system liquid/gas phase generators. Are they ever used in space or are solar panels that conver solar radiation the only choice? 71.100.5.197 (talk) 23:41, 2 March 2010 (UTC)

Solar heat is used on Earth (a rather extreme example). In space it may be used as well, but it isn't used because we don't have anyone that far out in space. I do not believe it is possible, at this time, to make an educated claim about what exactly will be used when manned spacecraft go well beyond the Moon and need plenty of methods of generating electricity and heat. -- kainaw™ 23:46, 2 March 2010 (UTC)

Actually I was thinking on a much smaller scale that the terrestrial based systems your link points to. I was thinking on the order of solar panels used to power the International Space Station for instance. I'm asking because such terrestrial systems used to heat and cool homes are far more limited in terms of efficiency due to the slight temperature differences between hot and cold whereas in space the very opposite is true. 71.100.5.197 (talk) 01:05, 3 March 2010 (UTC)

I would think that the issue is one of relative efficiency in terms of power generated per unit area and, more importantly, power generated per unit mass. I suspect that photovoltaics (given how thin they can be) come out on top over solar thermoelectric generation, but I don't know the numbers. 124.157.249.27 (talk) 01:03, 3 March 2010 (UTC)

For craft in a low orbit around a major body like a planet or a moon, the assertion that the plate would see the heat of the sun on one side and the cold of space on the other only applies for a small fraction of their orbit. When they are behind the body - then they are seeing only the temperature of the dark side of the planet on one side of the plate - and the temperature of space on the other. When they are between the planet and the sun, they'll see the temperature of the sun on one side and the temperature of the sun multiplied by the albedo of the planet on the other. That's much less effective than the ideal case. So it seems to me that this idea might be more useful for craft that either have very high orbits or are out in deeper space - than for the ISS - which orbits at only 300km or so above the earth and is only rarely in that ideal situation. Deep space missions tend to use radioactive heat sources to generate power if they are going far from the sun - and I presume the thermoelectric effect would be vastly less efficient out at the orbit of Jupiter and beyond - where the sun is a tiny dot in the sky and solar panels aren't a great deal of use. SteveBaker (talk) 13:38, 3 March 2010 (UTC)

March 3

salt peter

does eating potassium nitrate reduce testosterone? ( pilgrims did it to lower the sex drive ) how does it work —Preceding unsigned comment added by 67.246.254.35 (talk) 00:14, 3 March 2010 (UTC)

According to our article Potassium nitrate, "saltpetre is thought to decrease sex drive, but there is no scientific evidence to support that the substance causes such an effect". And the reference for that is Jones, Richard E.; Kristin H. López (2006). Human Reproductive Biology, Third Edition. Elsevier/Academic Press. p. 226. ISBN 0120884658, 9780120884650. --Tagishsimon (talk) 00:29, 3 March 2010 (UTC)

So, the myth that it causes impotence is just a big boner (def. 3) ? StuRat (talk) 18:30, 3 March 2010 (UTC)

Batman agrees. 86.177.121.239 (talk) 20:37, 3 March 2010 (UTC)

I had a teacher in school who hopefully was unaware of the more recent definition, and returned from the copy room with both sides of the test copied over the top of each other on the same side, only to say "I just pulled a giant boner". We never quite thought of that teacher the same way again. StuRat (talk) 19:18, 4 March 2010 (UTC)

brine shrimps

How long do brine shrimps live in enclosed containers? can they live longer if they break open the container and put them in a fish tank?? —Preceding unsigned comment added by Delvenore (talk • contribs) 02:10, 3 March 2010 (UTC)

Do you mean: “how long will their dormant cysts remain viable in a closed container?” The answer to this is easy: nobody is sure! anhydrobiotic animals are extreamy tollerant to harsh conditions when in this state. See: NASA article A Pothole in the Road of Life By: Leslie Mullen. This means that they will survive many years longer in this state than in a fish tank (year at most)-especially if the fish are hungry. --Aspro (talk) 14:56, 3 March 2010 (UTC)

Why would anyone use a pH meter instead of an indicator for acid-base titrations?

I've only used an indicator for acid-base titrations but I heard that some people use a pH meter instead. I don't really see much difference other than that indicator only works in certain pH range and pH indicator works in all pH. —Preceding unsigned comment added by 70.68.120.162 (talk) 03:57, 3 March 2010 (UTC)

A pH meter gives you a more precise value for your solution's acidity, which is why we use it whenever we have to make an acid-base buffer or otherwise adjust a solution's pH within a narrow range. Clear skies to you 24.23.197.43 (talk) 05:16, 3 March 2010 (UTC)

Rate of freezing vs temperature

Which would you say would freeze the fastest: Boiling hot water, room-temperature water, cold water? Explain. 198.188.150.134 (talk) 08:19, 3 March 2010 (UTC)

Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misevaluation, but it is our policy here to not do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn how to solve such problems. Please attempt to solve the problem yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. A hint, though: Mpemba effect -- Aeluwas (talk) 08:53, 3 March 2010 (UTC)

Nope, this is not a homework question! Just because I put the word "Explain" doesn't imply that at all. I was merely curious ever since I've read about the mpemba effect. I know hot water freezes quicker than cold water but what about room-temperature water vs cold water? Which freezes faster then? 198.188.150.134 (talk) 08:57, 3 March 2010 (UTC)

Why not try it and see for yourself? I'm sure it will be an interesting experiment. (A word of caution: Putting boiling water in the freezer may cause the container to shatter due to thermal shock.) 24.23.197.43 (talk) 09:28, 3 March 2010 (UTC)

There has to be some clarification and some care taken in defining our terms here. The Mpemba effect isn't magic. Boiling water has to become cold before it can freeze - so what this experiment says is that there are two kinds of "cold water" - the kind that has just come out of the cold tap of your sink - and the kind that was boiled and then cooled down to that same temperature. But we know that one container of chemically pure water at a specific, uniform temperature is no different than any other identical container of pure water at the same uniform temperature then the two must freeze at the same rate. Since the boiling water first has to reduce in temperature and then freeze - it can't possibly freeze faster than cold water if we control all of the bizarre side-effects relating to the nature of the container, the stuff that's dissolved in the water, evaporation during the experiment and inhomgeneities in the temperature.

But the Mpemba effect does work in the kinds of uncontrolled situations that come up in simple experiments. It clearly shows that in an uncontrolled situation, the boiling water freezes faster (at least for some definitions of "freezes"). So this can't strictly be about the temperature of pure water in an idealized container - it's about some other aspect of the situation. Given that, there will undoubtedly be some variations on the experiment that take more care over the purity of the water, the container it sits in, etc that will make the results come out the way common sense would make you expect them to.

Our article on the effect lists several causes that have been considered but all of them are about the nature of the container or some other aspect of the way in which the experiment is conducted. For example, it is far from clear whether boiling water will freeze sooner than cold water if both are stirred continually - or if the boiled water is kept in a gas-tight container that would prevent water from escaping - thereby reducing the overall volume that remains to be frozen. It's not clear whether the boiled water does indeed completely freeze before the cold water - it's suspected that a thin crust of ice may form on the top of the boiled water but the liquid beneath take much longer to freeze than the initially cold water. The Mpemba effect is therefore not so much to do with the properties of water - but more to do with the definition of the results and the way in which the experiment is conducted.

We know that when careful experiments are done, the anomalous results vanish and the system behaves as common sense says it should. However, having said that, we don't have a single, proven answer for why this happens in the uncontrolled case - and it would be nice if more studies could be done so that we can put this one to bed with a clear, logical explanation.

The bottom line here is that if you want to make some ice-cubes fast, you might well get them to freeze faster by boiling the water first...but on the other hand, maybe you won't - a lot will depend on the water quality and the shape and material of your ice-cube tray.

But you should not take away from that the idea that the laws of thermodynamics need to be repealed or that water has some kind of magical memory effect (such as, for example, the homeopathy nut-jobs would have us believe). It's simply that the physics and chemistry of the general situation are a lot more complex than the simple statement "hot water freezes faster than cold" implies. The Mpemba effect should probably state something like "Some mixture of hot water with other dissolved ingredients in an open container where convection currents are not inhibited will first produce some freezing before a similar mixture that starts off cold completely freezes." - which is a much less strong statement (and frankly, one that would not have surprised anyone). SteveBaker (talk) 13:14, 3 March 2010 (UTC)

Aristotle would have explained the Mpemba effect as a clear case of Antiperistasis and left it at that. This video demonstration was put on YouTube less than a month ago. Cuddlyable3 (talk) 16:49, 3 March 2010 (UTC)

Night Purge Ventilation

I was wondering if this was an effective method of cooling a building in a relatively mild climate. I can't find much reliable information. I think it relies on venting a building during the night when the air is naturally cooler and having the air cross a thermal mass, which will store the 'coolness' (release heat into air) and then cool the building during the day when it it occupied and warmer. Thanks.---- —Preceding unsigned comment added by 69.181.156.221 (talk) 08:22, 3 March 2010 (UTC)

From what I understand of your description of this method, it may amount to something as simple as leaving the windows open at night. Yeah, I normally do that (I live down south), and I tell you, it really works, 'specially on cool autumn nights (not so much in midsummer, unfortunately...) 24.23.197.43 (talk) 09:39, 3 March 2010 (UTC)

See passive cooling. 75.41.110.200 (talk) 14:20, 3 March 2010 (UTC)

I don't think simply leaving windows open is all that effective, for the following reasons:

1) The thermal capacity of air is quite low. This means that most of the heat stored in a building is in the floors, walls, furniture, etc., not just in the air. Therefore, you don't just need to exchange the air once, but several times, allowing some of the heat from the floors, walls, and furniture to bleed off into the air each time.

2) Strong winds are required to force the air out of the building. Unless you have consistently strong winds in the proper orientation and a clear path through the building that exchanges all the air, you need to use intake and exhaust fans. Fans can still use far less electricity than A/C, however.

3) Humidity and rain can be an issue. Rain is easier to deal with, as an overhang can prevent rain from spraying in. Humidity, on the other hand, can be a real problem. Even if you lower the temp of the building, raising the humidity can make it even more uncomfortable, and more expensive to remedy with A/C. Therefore, exchanging air only makes sense where and when there's dry air outside. A desert would be a good choice, for example, with cool, dry air at night.

4) Papers can be blown around. This can be fixed, of course, if people know to secure all papers before they leave at night.

5) Windows don't open in many modern office buildings. This is a serious limitation when it comes to being environmentally friendly, leading to using A/C inside even when it's nice and cool outside, due to solar heating of the building and heat generated from the people and machinery inside. Screens are also required to keep insects, bats and birds out, and most office buildings don't have those, either.

6) Overcompensation can be an issue. To keep it cool all day long, you need to make it quite cold in the morning, perhaps so cold people would need to wear jackets. StuRat (talk) 14:50, 3 March 2010 (UTC)

Original research here: it works just fine in a small building in a semi-desert climate. Rain is rare, and the roof overhang common in residental structures takes care of that when it does happen. Strong winds are not required: you can exchange ventilation area for air speed, so (for example) a single large sliding door, a few windows, and a wind speed of one mile per hour can exchange the air in my apartment once every three minutes. --Carnildo (talk) 01:48, 4 March 2010 (UTC)

I'm rather skeptical of the 3 minute claim. How have you measured it ? Here's a test you can do: Let an egg rot in a sealed container (like a mason jar), then expose it to the air in the apartment. Open the windows and see if the stink completely disappears in 3 minutes. StuRat (talk) 15:26, 4 March 2010 (UTC)

I've done something similar: cook something with a strong odor, then see how fast the smell goes away after I put away the leftovers. The kitchen circulation isn't as good as the rest of the apartment, but it's still gone within ten minutes. --Carnildo (talk) 01:23, 5 March 2010 (UTC)

general principles of pharmacy technician practice

What are the relationship between the pharmacy technician and other health workers in an hospital setting. —Preceding unsigned comment added by Enipez (talk • contribs) 08:57, 3 March 2010 (UTC)

Um, they ask him for drugs, and he gives them what they asked for ? I have a feeling this a homework Q, so look through the book and regurgitate whatever they say about it. StuRat (talk) 22:21, 3 March 2010 (UTC)

Why bring eggs to room temperature?

Cookbooks always tell you to bring eggs to room temperature before using them in a recipe, such as for cake or cookies, but they never tell you why. (I know that people in many countries don't refrigerate eggs in the first place, so this question really only applies to those who do usually refrigerate them.) What difference does it make to my cake or cookie recipe whether the eggs are cold or not when I beat the eggs in? The batter/dough stabilizes to approximately room temperature by the time it's all mixed ready for baking anyway, doesn't it? +Angr 10:46, 3 March 2010 (UTC)

I'm not really sure, but it could have something to do with them being more viscous below room temperature (and therefore more resistant to being mixed into the dough). Clear skies to you 24.23.197.43 (talk) 11:02, 3 March 2010 (UTC)

Yes, that's the idea. Colder eggs will tend to clump together and form lumps in the batter. It's not a huge difference, though, and you could probably just beat the batter a bit more to get the lumps out, if you don't have time to wait for eggs to warm to room temp. StuRat (talk) 14:31, 3 March 2010 (UTC)

(ec)There are a couple of different reasons, depending on the application. For example, in an omelet the eggs should be warm because the short(er) thermal trip from raw to cooked gives you a shorter cook time and therefore a more tender end product. In other cases, such as where the egg (specifically the yolk) is being added to create an emulsion the warmer temperature helps reduce viscosity and allow for more thorough mixing (and therefore a more even texture), as 24.23 says above. Matt Deres (talk) 14:40, 3 March 2010 (UTC)

Perhaps also for the same reason recipes often call for unsalted butter only to later add salt: so that everyone's starting on the same page, whether they refrigerate their eggs or not. --Sean 16:43, 3 March 2010 (UTC)

Page 208 of Shirley Corriher's Bakewise says that room-temperature eggs beat faster and separate more easily. Similarly, page 122 cites a source who says that cold eggs give less volume. -- Coneslayer (talk) 16:56, 3 March 2010 (UTC)

Sexuality of Hedgehogs

I have three questions:

1. Are there any recorded cases of gay / lesbian hedgehogs?
2. Can and do hedgehogs masturbate?
3. Do hedgehogs experience orgasms? —Preceding unsigned comment added by Delvenore (talk • contribs) 11:03, 3 March 2010 (UTC)

I refer you to "The Hedgehog Song".http://www.youtube.com/watch?v=wmPeX6syPPY (Warning: lyrics NSFW) --TammyMoet (talk) 13:00, 3 March 2010 (UTC)

The Wikipedia article Hedgehog has a section about the animal's reproduction that mentions that their physical difficulty of mating has a counterpart in human psychology. Cuddlyable3 (talk) 17:22, 3 March 2010 (UTC)

Not exactly Cuddlyable3. The article Hedgehog explains why it is not a problem for a hedgehog to have a sexual encounter with a female hedgehog.

From the article: "The hedgehog's dilemma is based upon the apparent danger of a male hedgehog being injured from a spine while mating with a female hedgehog. However, this is not a problem for hedgehogs as the male's penis is very near the center of its abdomen (often mistaken for a belly button) and the female has the ability to curl her tail upward to the point that her vulva protrudes behind the rest of her body. As such, the male doesn't have to get completely on top of the female when mating."--Quest09 (talk) 18:16, 5 March 2010 (UTC)--Quest09 (talk) 18:16, 5 March 2010 (UTC)

inhaling

I learned that when smoking marijuana it is more effective to "hold it in" for as long as possible after inhaling to maximize the amount of THC taken in. Is this tactic effective? —Preceding unsigned comment added by ShadowFire101001 (talk • contribs) 11:17, 3 March 2010 (UTC)

Probably, but it will also maximize the amount of tar that ends up in your lungs. Eating "special brownies" or taking THC capsules would be far more effective at getting the good stuff without the bad. StuRat (talk) 14:19, 3 March 2010 (UTC)

In USA Marihuana Tax Act of 1937 criminalised sale and use of Marihuana which is a preparation of the Cannabis plant. It is a Class B controlled drug in the UK. Smoking of cannabis is the most harmful method of consumption and brings the user into close or actual involovement with Drug abuse, illegality and drug peddlers.THC is only one of the active chemicals that a marihuana smoker ingests. Some research suggests THC may have some medicinal value besides its toxicity and negative mental effects. It is irresponsible to encourage anyone to self-medicate with THC derived by smoking, as might be inferred from StuRat's expression "the good stuff". Cuddlyable3 (talk) 14:52, 3 March 2010 (UTC)

Who is asking anyone to self-medicate? Is it more irresponsible than telling someone how to mix a good drink? What if the original poster is in a jurisdiction where marijuana is legal? Just pretend the poster asked: "Is the transference of THC to the bloodstream maximized by holding in the inhalation of marijuana smoke, or is that a myth?" A perfectly good science question. --Mr.98 (talk) 15:28, 3 March 2010 (UTC)

That's 3 supplementary questions. Answers in order: 1) Nobody asked. StuRat encouraged, see above. 2) Yes. 3) Legality does not make an action harmless. No, we don't rewrite an OP's question. Cuddlyable3 (talk) 17:04, 3 March 2010 (UTC)

1) No, I didn't.

2) Wrong. Alcohol is far more harmful, as numerous studies and statistics have shown.

3) It's absolutely true that being legal doesn't make something harmless, as in the cases of alcohol and tobacco. Conversely, being illegal, ostensibly for health reasons, in no way means that the substance is actually harmful. Unfortunately, lobbying by powerful interests has far more impact of what is legal or criminalized than science ever will. StuRat (talk) 17:44, 3 March 2010 (UTC)

So... let me get the right: we shouldn't tell someone about marijuana, because they might continue doing exactly what they already said they are doing. StuRat (and my) answer is actually one that encourages one to do the less harmful practice here—emphasizing the lung damage that comes from such activities (and such myths). Whether you think people should abstain from consuming THC in any form or not seems irrelevant here. Anyway, no one is encouraging anyone to do anything (other than not believe harmful myths!). In any case, this is a topic that has been researched by real-deal scientists, so I think that by itself should give us some clue that it's not an illegitimate question for the Science ref desk. (In any case, the post doesn't say that the poster actually smokes—just that they "learned" this myth from someone.) --Mr.98 (talk) 17:51, 3 March 2010 (UTC)

1) StuRat identified THC as "good stuff" and thereby endorses ingesting THC with no warning or qualification. That is not NPOV and a drug peddler's pitch would sound the same.

2) Good drinks are not necessarily alcohol drinks. StuRat's argument is to introduce a strawman because mixing alcohol drinks has nothing to do with self-medication with THC.

3) I answered the question "What if....legal" with a truth that StuRat agrees.

Cannabis has been judged by many to be so harmful that it must be controlled by laws. It is okay to debate the medical evidence for those judgements. But StuRat cannot dismiss such a weight of evidence and legal opinion merely by claiming that it "in no way means" anything. The rant about alcohol, tobacco and alleged "powerful interests" is OT. StuRat claims science will always be impotent in guiding legislation but that prediction is crystal ball gazing. Cuddlyable3 (talk) 03:04, 4 March 2010 (UTC)

1) There's plenty of medical evidence or the benefits of THC: [6], but that really isn't relevant the the Q, which was how to increase absorption of THC. Whether they should is not the Q (and would be a request for medical advice).

2) You know very well that the phrase "drinks" was used in this context to mean alcoholic drinks. Pretending otherwise is disingenuous.

Science should never be based on useless "legal opinion". When we do so we get really bad science, like Galileo being forced to say that the Sun revolves around the Earth, in order to comply with the law. I don't know what "OT" means, did you mean OR (Original Research) or OTT (Over The Top) ? The La Guardia Committee was an early scientific inquiry which determined that marijuana was not as harmful as politicians, specifically Harry J. Anslinger, claimed in their justification for criminalization. StuRat (talk) 15:05, 4 March 2010 (UTC)

1) StuRat you use the qualifier plenty to tell us that your opinion is that there is enough evidence to justify what you endorse. I say your endorsement of THC as "good stuff" is reckless and opinionated. Your alleged plentiful evidence hasn't overwhelmed the medical world yet.

2) Please use any English dictionary to help you comprehend the word "drinks". It is a word not a phrase. If you mean "alcoholic drinks", "carbonated drinks", "hot drinks", "cold drinks" or any other category of drinks then make the effort to write what you mean. Contrary to your false claim, I did not know that you meant "alcoholic" drinks because I don't read your mind.

OT stands for Off Topic. If you now imagine yourself as a champion of good science like Galileo Galilei and living in a world where legalities are mere useless opinions then you have detached yourself from reality as well as social responsibility. Cuddlyable3 (talk) 21:54, 4 March 2010 (UTC)

1) Since you are the one claiming THC does more harm than good, it's your responsibility to back that claim up with evidence, not mine.

2) You are either unaware that the meaning of words is dependent upon the context in which they are used, which would mean you suffer from a learning disability, or are just pretending to not know what the word meant in this context, to be difficult. Clearly (to everyone but you), the word "drinks", in the context of a discussion of another drug, THC, refers to drinks containing a drug, namely, alcohol. And that would be ethyl alcohol, just in case you are unable to determine this from the context, due to your learning disability. If you are really that incompetent to not understand what words mean in context, then you shouldn't be (trying to) contribute here. And you also seem to think that I used the word initially. I didn't, Mr. 98 did.

If you imagine that legal opinions carry any weight in the scientific world, it's you which have detached yourself from reality. More recent cases involve the teaching of evolution. But, I guarantee that scientists won't change their stance on evolution based of whether the law decides it can be taught or not. StuRat (talk) 23:24, 4 March 2010 (UTC)

1) False premise. I have made no such claim.

2) StuRat's response violates WP:NPA. Otherwise StuRat's retort is a collection of fallacies, still defending the notion that the qualifier "alcohol" must be assumed where it does not exist because that would be part of Mr. 98's pro-marihuana smoking rhetoric.

StuRat must be informed that:

• The Ref Desk is not the place for pursuing an opportunistic debate that is OT to the OP.
• StuRat may argue about marihuana in an apropriate forum. StuRat would be wise to avoid hand-waving claims of having plenty of evidence, denial of the function of Law in civilised society, personal insults, and ridiculous parallels to Galileo and Evolution.

I have identified in red the abuse by StuRat to help intervention stop this. Cuddlyable3 (talk) 13:51, 5 March 2010 (UTC)

As for answering the question... what you're asking about, in medical terms, is whether "breathhold duration" affects the absorption of THC or not. As far as I can tell from a few articles on Google Scholar, the answer seems to be, "probably not." On the contrast, they do seem to be associated (as StuRat said) with higher levels of tar, which is bad. My skimming of the literature seems to imply that volume of smoke matters (which makes sense), but breathhold duration does not. (This page has a lot of references to studies on it, along with summaries of their conclusions.) So, without wanting to give any kind of medical advice, I would tend to think that a marijuana smoker would be better off not holding their breath for a long time, as it does not seem to increase THC absorption, and does more lung harm that way. --Mr.98 (talk) 15:37, 3 March 2010 (UTC)

Bill didn't inhale. (video) Cuddlyable3 (talk) 17:08, 3 March 2010 (UTC)

And, based on some of W's statements, I'd have to say he's "still waiting to exhale". StuRat (talk) 22:12, 3 March 2010 (UTC)

No, you don't have to say anything. But anything you do say will be used to judge you. Cuddlyable3 (talk) 03:04, 4 March 2010 (UTC)

String theory

How many degrees of freedom does a string have ie the largest possible set of commuting observables? What are these degrees of freedom? 174.112.66.226 (talk) 13:13, 3 March 2010 (UTC)

I seem to recall that there are many variants on string theory, some of which have closed strings (loops) and others of which have open strings. I suspect that this would result in a variable number of degrees of freedom. StuRat (talk) 16:42, 3 March 2010 (UTC)

Yes, I was aware of this. In fact, many string theories have both closed and open strings. 174.112.66.226 (talk) 17:32, 3 March 2010 (UTC)

Would the number of degrees of freedom correspond with the number of dimensions, in each version of string theory ? StuRat (talk) 18:21, 3 March 2010 (UTC)

I doubt it; there should be more degrees of freedom than dimensions, since a string is not a point particle; it has substructure. I want to asking what degrees of freedom this substructure has, since I was already aware of the position/momentum/angular momentum degrees. 74.14.111.8 (talk) 21:52, 3 March 2010 (UTC)

But aren't there extra hidden dimensions associated with that internal structure ? I don't believe that string theory limits itself to the familiar 3 linear and one temporal dimension. StuRat (talk) 22:07, 3 March 2010 (UTC)

There are extra spatial degrees of freedom, but, even if all dimensions are treated as spatial rather than internal, there are still more degrees of freedom than a point particle in 10/11/26 dimensions would have. 70.27.196.12 (talk) 01:30, 4 March 2010 (UTC)

"Dimensions" in string theory is really code for the number of independent degrees of freedom, so there are 10 or 11 or 26 depending on the assumptions of the theory. The classical picture of a physical string with substructure that might be arbitrarily positioned really isn't helpful since the eigenstates of a quantum string are only allowed to be pure vibrations with an integer number of waves. Dragons flight (talk) 02:08, 4 March 2010 (UTC)

Thank you for your answer. Just to make sure I fully understand you, does that mean that a single string without interactions would behave identically to a point particle in however many dimensions with an extra quantum number representing the number of waves? Wouldn't a string's vibrations require a plane of polarization? 70.27.196.12 (talk) 03:24, 4 March 2010 (UTC)

Your question doesn't really make sense. If you imagine a physical string tied to a post, then you might shake it right-left and up-down. Those would be two dimensions. In string theory, the number of dimensions specifies the number of "ways" in which one can "shake" the string. For each dimension there would exist an integer specifying the number of waves in that direction (subject to various technical constraints). Once you specify all 10 (or 11 or 26) integers you have completely specified the properties of some possible particle. How those integers map onto conventional quantum numbers is not necessarily trivial however. Dragons flight (talk) 04:28, 4 March 2010 (UTC)

Oh, I get it now. 99.237.180.215 (talk) 17:07, 4 March 2010 (UTC)

mass/weight question

Does a Pokemon retain the same mass/weight when inside its Pokeball —Preceding unsigned comment added by Teltala (talk • contribs) 13:30, 3 March 2010 (UTC)

According to Gameplay of Pokémon#Poké Ball, the Pokémon is converted into energy when put into the Poké Ball. You may like to read mass–energy equivalence to see what happens when mass is "converted" to energy. +Angr 13:53, 3 March 2010 (UTC)

Also, I'd ask a fictional Q like this at the Entertainment Desk, not here. StuRat (talk) 14:16, 3 March 2010 (UTC)

Science for Dummies website

Any suggestions for websites for the scientifically challenged? What I would like to do is read about a certain topic then do my own research on Wiki. BTW, I am a fan of Neil deGrasse Tyson's approach to teaching astronomy, for instance. --Reticuli88 (talk) 13:47, 3 March 2010 (UTC)

Simple Wikipedia. Cuddlyable3 (talk) 14:21, 3 March 2010 (UTC)

Well, there's the PBS website. You might like the Discovery Channel, too. Also, you might want to get the book Cosmos by Carl Sagan or rent the series on DVD. StuRat (talk) 14:23, 3 March 2010 (UTC)

Thank you,thank you Cuddlyable! Did not know this existed! Thank you!--Reticuli88 (talk) 14:25, 3 March 2010 (UTC)

Simple Wikipedia is written in a simplified form of English. It uses a restricted set of words in its articles, but that doesn't mean it makes science topics easier to understand for non-scientists. I still find simple:Quantum mechanics very difficult to understand, for example. +Angr 16:13, 3 March 2010 (UTC)

It may be an unpleasant truth that some topics will be dificult to wrap your mind around regardless of how well it is explained.

There are two types of simplification, those which still present the full material, but in an easier to understand fashion, and those which actually present a simplified (and thus less technically accurate) model. For example, subatomic physics gets quite messy when electrons are thought of as a quantum probability function, but is far easier to picture when they are thought of as little balls orbiting the atomic nucleus in circular rings. Depending on the audience, this simplification may be entirely sufficient, as it is for most chemists, for example. StuRat (talk) 17:31, 3 March 2010 (UTC)

See lie-to-children for more on this kind of simplification. -- Coneslayer (talk) 19:06, 3 March 2010 (UTC)

There are many adults, even scientists, which use simplified models for the majority of their work, such as the atomic model used by most people in the chemistry industry. For another example, Newtonian physics is used for almost all real-world calculations, as time-dilation and other relativistic effects simply aren't significant when, say, designing a car bumper. StuRat (talk) 19:31, 3 March 2010 (UTC)

The article I linked to says The word "children" should not be taken literally and Such statements are not usually intended as deceptions, and may, in fact, be true to a first approximation or within certain contexts. (However, I would also point out that there's a difference between using a simplification in your work, and teaching that simplification as "the truth." Lies-to-children is specifically about pedagogy, not simplification/approximation as strategy in problem solving.) -- Coneslayer (talk) 19:51, 3 March 2010 (UTC)

Yes, and that's why it's not particularly relevant to what I was talking about. StuRat (talk) 20:02, 3 March 2010 (UTC)

Depending on the type of science question How Stuff Works might be OK. APL (talk) 16:23, 3 March 2010 (UTC)

Turbulent gas

I have a gas stove. When I turn it on low, it makes a steady hissing sound and each of the flame tips stays blue and at the same height. When I turn it up high, it makes a sound more like a windy day, and the flame tips flicker in and out and up and down with flecks of orange mixed in with the blue. I assume that the first case is laminar flow and the second case is turbulent flow. Is this correct ? Also, does turbulent flow lead to less complete combustion, and thus more unburnt gas and carbon monoxide released into the air ? StuRat (talk) 15:27, 3 March 2010 (UTC)

you should probably clean the burners - you shouldn't get turbulent flow like that, even under high pressure. It's difficult to say whether you are getting less complete combustion or more diffuse combustion - both would produce orange flame because the combusting elements are less concentrated. --Ludwigs2 16:08, 3 March 2010 (UTC)

Have a look at the illustration of flames at the article Bunsen burner. Cuddlyable3 (talk) 20:58, 3 March 2010 (UTC)

That seems to imply that the orange flame is a sign of insufficient air for the gas volume, and thus incomplete combustion. StuRat (talk) 21:19, 3 March 2010 (UTC)

Traffic

Is it legal to travel down a road in reverse, as long as your following the direction of the traffic? —Preceding unsigned comment added by Dendalonger (talk • contribs) 16:03, 3 March 2010 (UTC)

no. --Ludwigs2 16:09, 3 March 2010 (UTC)

Specific laws will apply in different jurisdictions. In the UK, if I recall correctly, the Highway Code says that one may reverse only as long as is necessary for the manoeuvre one is doing (turning, parking, backing out of a space or away from an obstacle); I don't think it specifies an actual distance. -- Finlay McWalter • Talk 16:11, 3 March 2010 (UTC)

Or there's the cover-all driving without due care and attention, a bucket designed to scoop up the many stupid things one can do with a car. FMcW is right: section 203 of the Highway Code says "You MUST NOT reverse your vehicle further than necessary."--Tagishsimon (talk) 16:12, 3 March 2010 (UTC)

every jurisdiction I know of has generalized laws against driving in a fashion that endangers other people. Trying to drive a car in reverse under normal traffic conditions will inevitably constitute endangerment - difficult body posture, poor visibility, poor steering control, and etc all add up to lessened control over the vehicle. ** --Ludwigs2 16:19, 3 March 2010 (UTC)

** = deleted part of post. Cuddlyable3 (talk) 16:53, 3 March 2010 (UTC)

On single-track roads it is legal and often necessary to reverse for a hundred yards or more to find a place wide enough when meeting a vehicle travelling in the opposite direction. Those who regularly drive on such roads become adept at reversing at speed. Such roads are perhaps rare in the USA. Dbfirs 02:07, 4 March 2010 (UTC)

Most such roads (in the UK, at least) have regular passing points, so 100 yards would be unusual. If one (or both) of the vehicles is particularly wide (I was once on a bus that met a horse-box on a narrow road) then much more reversing can be required. This is all consistent with what has already been said - you can reverse for as far as it necessary. Sometimes it is necessary to reverse 100 yards, so you are allowed to do so. --Tango (talk) 04:53, 4 March 2010 (UTC)

They aren't rare in the US, just rarely traveled. Most of them are logging roads or other limited-use roads. --Carnildo (talk) 01:32, 5 March 2010 (UTC)

Nothing but the tooth

Resolved

I hear a lot about how acidic drinks, like soda pop, dissolve the teeth, leading to cavities. How about alkaline drinks ? Are there any, and are they bad for the teeth ? StuRat (talk) 16:45, 3 March 2010 (UTC)

Unless you happen to drink them both at the same time (and in the same proportion, such that they balance each other out), conventional wisdom tells us that alkaline (caustic) liquids can be just as damaging, in similar ways, as acidic liquids. As far as their existence, there certainly isn't anything that rivals the prevalence of carbonation/phosphate additive in modern drinks. Probably thanks to the pretty bad reaction they have with the taste buds.--144.191.148.3 (talk) 17:00, 3 March 2010 (UTC)

There just aren't many alkali foods at all. Alkali foods have a very bitter taste; there are a few foods which are processed with alkali (like Dutch process chocolate and Hominy). However, in these foods, the alkali is often washed away, and the food itself is used in applications that returns them to a more neutral or slightly acidic state. The only food I can think of which is eaten in a strongly alkali state is lutefisk, the taste of which can most charitably be described as "soapy". Generally speaking, however, nearly all foods lie on the lower side of 7 on the pH scale. --Jayron32 17:07, 3 March 2010 (UTC)

So, basically, there are no alkaline foods or drinks. I don't think that's a lye, but what about sour balls ? StuRat (talk) 17:22, 3 March 2010 (UTC)

Sour tastes are generally associated with acid not alkali. Googlemeister (talk) 17:35, 3 March 2010 (UTC)

<Facepalm>... Sour flavor, when added artificially, is often from citric acid or ascorbic acid. The kind of sour that you experience when tasting alkalinity is a less desirable one, to say the least. --144.191.148.3 (talk) 17:46, 3 March 2010 (UTC)

Baking soda is alkaline, right, and people use it to clean their teeth, right? Looie496 (talk) 21:40, 3 March 2010 (UTC)

Indeed, but you don't generally ingest a dentifrice; you spit it out. Likewise, while the alkali baking soda is often used as part of cooking, the end product which you actually eat, like a bread or a cake, is not actually alkali, it is usually very close to neutral or slightly acidic. --Jayron32 21:50, 3 March 2010 (UTC)

Tooth structure demineralizes at an average pH of 5.5 (I say average because enamel, dentin and cementum are of different compositions and relative mineralization and will dissolve at different pHs). The general formula for hydroxyapatite (tooth mineral) is [Ca₅(OH)(PO₃)]₂ -- two molecules in a united pair. An acidic environment will draw the hydroxyl group out of the hydroxyapatite, causing it to dissociate. That's why F^- is provided to protect teeth from demineralization -- despite what our article on Hydrofluoric acid states, dental text books promote the idea that HF moves towards ionization with such power that a proton will virtually never be able to pull the F^- out of fluoroapatite as it would the OH from hydroxyapatite, and there you have acid-proof tooth structure. As a dentist, I never really thought about the effect of alkaline on teeth, but seeing how the theory promoted by the texts and professors is that the OH is pulled from the tooth by protons, alkaline would be able to accomplish no such similar thing. DRosenbach ^{(Talk | Contribs)} 02:58, 4 March 2010 (UTC)

Thanks. With that I'm marking this Q as resolved, as "alkaline foods and drinks are rare, and, even then, they don't cause tooth decay". StuRat (talk) 16:13, 5 March 2010 (UTC)

Another alkaline food would be Century egg a resonably common Chinese ingredient in East and South East Asian food. However unless the egg is eaten by itself (which it is) the prepared food may not be alkaline. We also have Food preservation#Lye albeit without much other then what's discussed here. Lye#Food uses has a bit more, although probably not all of those are alkaline after treatment, you'd have to check out the individual articles or whatever to find out. Nil Einne (talk) 06:00, 12 March 2010 (UTC)

Fire drills

I've often thought that fire drills might actually harm more people than they help, when people, especially kids, are forced to stand outside in the cold, without coats, for hours at a time. I'd also include over-reactions, like when a waste-paper basket catches fire and is immediately extinguished, but the entire building is evacuated anyway until the fire department comes out and gives the "all clear". So, my questions are as follows:

1) Is the potential harm done to people by having them stand out in the cold without coats considered when scheduling drills, or reacting to minor fires ?

2) Does any jurisdiction prescribe methods for handling this, such as having blankets available in a shed in the evacuation area or a plan to move evacuees to a warm building nearby ? StuRat (talk) 17:15, 3 March 2010 (UTC)

Can you cite a source for the claim that fire drills cause people to stand outside in the cold without coats "for hours at a time"? Can you cite a source that standing in the cold causes harm to people? I mean, it's uncomfortable and annoying, but people aren't dropping dead from hypothermia during a fire drill, and the common cold is not contracted via exposure to colder weather. Comet Tuttle (talk) 17:36, 3 March 2010 (UTC)

I just saw a case on TV where kids were outside for 2 hours, and shivering severely, until a bus came to take them someplace warmer. In this case it was a bomb threat, but I've personally seen fire drills and reactions to minor fire events that have involved similar-length evacuations. StuRat (talk) 18:00, 3 March 2010 (UTC)

Given that the fire, the smoke from fire, or the panic from being unprepared for said fire all account for many many tragic deaths each year, I am going to venture the argument that spending 5 to 10 minutes outside in 'uncomfortable' weather to instill good fire preparedness is well worth it. If you are really standing outside for hours on end for a drill, or are doing it during truly inclement weather, your safety coordinator probably needs to find a new outlet for his masochism. Where I am in the US, we do fire drills every so often, and it's not on a bad weather day (since there is discretion during planning for a drill) and it never takes more than about 5 minutes of my time. Were this a high-rise building of some sort, I could see it taking maybe 15 minutes to get everyone out, accounted for, and back in but if the process to conduct the drill takes hours on end, imagine the hassle of fleeing an *actual* fire! --144.191.148.3 (talk) 17:51, 3 March 2010 (UTC)

But keep in mind that people probably evacuate 1000 times for every actual life-threatening fire. So, if only a few kids get sick each time, it may end up worse than the many injuries and deaths in actual severe fires. StuRat (talk) 18:00, 3 March 2010 (UTC)

It's one thing to say a few kids get sick, and a whole 'nother thing to say they get sick enough to perish. --Sean 19:59, 3 March 2010 (UTC)

Not really. Anything that makes thousands of kids sick (like millions of kids forced outside in the cold without coats) will probably kill a few of them, either directly or indirectly, as when their immunity is still low when they get some other fatal condition, or when the doctors kill them via medical error. The problem, though, is that the death certificate won't say "killed by a fire drill", so no statistics will be kept or action taken to prevent further such deaths. StuRat (talk) 20:11, 3 March 2010 (UTC)

As for evacuating a building for minor fires...Personal experience: two peoples' work went up in flames when someone (I think) knocked over a Bunsen burner in a chemistry lesson. The teacher came long, tipped the flaming work into the sink, then continued with the lesson. (The sink was wet; the fire went out almost immediately). No alarms, no evacuations, no-one had to leave the room. But, I live in Britain; where are you writing from? And to add to what the others have said - our drills were 10-15 minutes, and our accidental alarms were about 20. Vimescarrot (talk) 17:57, 3 March 2010 (UTC)

Well, if it never triggers the alarm, that might happen here in the US, too. But once an alarm goes off, I think schools are obligated to do a full evacuation. There are places in the US where the temp goes down to -40 in winter, and even a few minutes at those temps without coats could cause medical problems, even death. StuRat (talk) 18:03, 3 March 2010 (UTC)

The problem with fire is how rapidly something that "looks" small can become a huge and threatening danger. The general public is terrible at recognizing that fact, and even in cases where someone recognizes the real extent of a developing disaster, how do you convince others that they need to react a certain way, now, without panicing? And children certainly don't have the the experience to recognize and react properly to emergencies or the urgency of "get out now" vs "if you're a few minutes late wandering out for recess, that's okay". So instead, we have a plan that works in all normal situations rather than relying on those who are maybe not capable of making the correct judgement (and finding that person, and having him/her examine/decide, which takes time, etc.). And drills are a rehearsal so that when the actual performance comes, you don't have to figure out and read the instructions for the very first time in a situation where there isn't time. It's easy: "fire? pull alarm." "fire alarm? get out."--the potential for harm (and harm to others not just self) if you make either of those optional/judgement is huge. Modern buildings often have fire-alarm zones, so pulling in one area doesn't dump other areas, but that requires more complicated wiring of the alarm system and (more importantly) that the areas are strongly firewalled from each other. Different wings of a sprawling complex are like this. Also, tall buildings are sometimes zoned "alarm floor and the one immediately above it". That latter is interesting...it recognizes that fire tends to go up and that stairwells are a often bottle-neck so best to get the most-threatened people out asap rather than clogging the exit with downstairs people. Getting back to the risk/trade-off, somehow we ("public policy in the US") lean heavily towards "better safe than sorry", even if there are health risks and real costs of that safety. We usually go to an extreme to prevent disasters or react properly to them, even if they are likely to be rare, because disasters are so disasterous and unpredictable.

One of the funniest (in a scary way) things I've seen is a lab-safety training session on using fire extenguishers. Now this is a place where fires are a real possibility, they are detected immediately, can be extinguished rapidly, and if so there is little risk of spreading (but if not, can easily take out the whole building). And everyone knows "read the instructions on the extinguisher" (and even most knew "PASS-- pull, aim, squeeze, sweep"). So everyone's given an extinguisher and told "now use it". Usually takes several minutes (!) before the first person actually gets it discharged, and this was not in a panic with real risks as time runs and where the situation itself isn't predictable. DMacks (talk) 19:14, 3 March 2010 (UTC)

It actually might go better in a real fire, as nobody would try reading the instructions, which are probably full of time-wasting advice like "never insert the hose into your anus". :-) I hope I didn't put beans up anybody's nose :-) StuRat (talk) 19:24, 3 March 2010 (UTC)

Schools in the U.S. always did the fire drill, but after the Our Lady of the Angels School fire in 1958 killed 92 children and three nuns, when a fire started in the old firetrap school, there was a delay sounding the alarm, the wrong address was given to the fire department, and there was a lack of fire escapes, school fire safety became a much greater concern, and the drills were taken seriously. Did all parts of the building hear the promptly sounded alarm, and did they line up and leave in an orderly fashion in an acceptably short time? In a 1954 fire referenced in the first article,860 students in "Gadsden" safely exited in 2 minutes. Strangely, in one 1956 school fire, the Principal told the students it was just a fire drill, "to prevent panic." At Our Lady, a teacher escorted her pupils out, then went to notify someone in authority, rather than someone seeing smoke minutes earlier and sounding a central alarm. That fire also resulted in physical safety improvements, like better fire alarms and the installation of lockers in hallways to prevent clothing on pegs feeding the fire. Schools in the U.S. and elsewhere were inspected and many old schools were promptly closed. The frequency of fire drill was increased. Millions were spent on alarms, sprinklers and improved fire escapes, including security doors which opened automatically in a fire, and automatic alarms to fire stations. [7]. Fireproofing was added to over 16000 schools in the U.S. as a result of the fire, and 68 % of U.S. communities adopted stricter fire codes for schools.[8] Edison (talk) 19:25, 3 March 2010 (UTC)

And I'd be in favor of most of those things, but that doesn't mean nothing should be done to protect kids from cold during drills and actual fires. As for modern risks, I bet many inner-city schools chain the doors shut during the day, to prevent unauthorized access to the school by drug pushers and such. Unfortunately, I doubt if a fire drill would address such an issue, as the staff would just unchain the doors before the drill, then chain them back up again after recording a successful evacuation. A kid pulling a fire alarm would actually be a better test of whether the staff can get the doors open in time. StuRat (talk) 19:56, 3 March 2010 (UTC)

I know of no school which does that (and I have friends who teach high school in the Bronx). Unless you have a source, that sounds incredibly unlikely, due to the safety implications you mention. It's much simpler to simply make doors that can only be opened from the inside (without a key), and doors like those are used on many, many schools, not just those in the "inner city". —ShadowRanger ^(talk|stalk) 20:07, 3 March 2010 (UTC)

Here's a source: [9]. Doors that open from the inside only can still be used for criminal acivity with an accomplice on the inside, such as the student who wants to buy the drugs. You probably need a guard (possibly armed) at each door to both keep criminals out and allow a quick exit in the case of a fire, and that would be expensive. StuRat (talk) 20:42, 3 March 2010 (UTC)

Or you just alarm the door so the fire alarm goes off if opened, that way someone can't use it to sneak drugs into the school and it still works as a fire door. 82.132.139.83 (talk) 22:48, 4 March 2010 (UTC)

That was mentioned elsewhere. Kid opens door and gets drugs, alarm goes off, kid runs like hell and gets away, guards get pissed and chain door shut. StuRat (talk) 01:17, 5 March 2010 (UTC)

See the article Fire drill. The regularity of fire drills may be set by local authority rules. Examples in US. The purpose of the drill is to assess how long it takes to confirm that everyone has evacuated which imposes a certain waiting time that may be uncomfortable, though real harm to anyone is unexpected. Fire protection equipment such as blankets, hoses, extinguishers and alarms in a building is for immediate emergency response and dealing with unharmed evacuees is not a priority. Cuddlyable3 (talk) 20:45, 3 March 2010 (UTC)

They should do a proper cost/benefit analysis of fire drills, which includes a proper evaluation of the down side of such drills. I would expect them still to be worthwhile, but some measures should probably be taken to limit risks to kids during drills. There's also the risk that fire alarms can be used by terrorists to get kids outside where they can be attacked and killed, as they were here: [10]. StuRat (talk) 21:38, 3 March 2010 (UTC)

As opposed to the cost of paying out multi-million dollar wrongful death settlements after an actual fire kills some of your students? Or any number of other issues that chaining the doors shut would cause? They hire the security anyway, because the students themselves can be drug dealers or become violent. The easy solution to the case you describe is to have most of the doors alarmed. Then you only need one or two guards to cover the doors without alarms that are used regularly. Since the schools already have metal detectors installed, they need one or two guards to man them in the morning. You're being intentionally obtuse; try and think about what you're saying for a second or two before posting drivel. —ShadowRanger ^(talk|stalk) 20:51, 3 March 2010 (UTC)

"The door is alarmed ? Why, did you threaten to chop it up with an axe ?" :-) StuRat (talk) 21:10, 3 March 2010 (UTC)

Please don't get abusive. A door with an alarm on it isn't necessarily effective, as the kid who opens the door can probably run and hide before anyone responds to the alarm and catches him. Adding a video camera would help, but the kid could always cover his face as he opens the door, gets some drugs from someone outside, then run and hide. After this happens several times, the guards might stop responding altogether. All those doors with alarms and video cameras would also start to get expensive. One or two guards won't stop this, you'd need one for every door. As for the cost of a multi-million dollar lawsuit, the administrator who orders the door locked won't pay any portion of that, and, if there isn't a fire, they aren't likely to be punished at all. StuRat (talk) 21:10, 3 March 2010 (UTC)

By law, there needs to be a certain number of exits available, well-signed and accessible, that can be nearly instantly operated by nearly anyone. Your local fire marshal would be happy to give the building manager the option of either unblocking them or else having their occupancy permit revoked for violation of building/life-safety code, and your local news media would love to do an investigative report of a school (especially one in New York) that didn't learn from the Triangle Shirtwaist Factory fire. One popular design is doors with have electronic locks that unlock automatically by fire-alarm system. DMacks (talk) 20:55, 3 March 2010 (UTC)

I don't trust "automatic" locks not to lock people in during a fire. Some fairly complex electronics needs to work properly for the fire to be detected and for the doors to open. StuRat (talk) 21:30, 3 March 2010 (UTC)

Trust (or not) is certainly your prerogative, but "cut power to electromagnet" doesn't seem more complex than "send power to bell-ringer". DMacks (talk) 21:33, 3 March 2010 (UTC)

It's how to determine when to cut that power that's the issue. Do you do it when a fire alarm is pulled ? Then the kid who wants his drugs will pull the alarm, open the door, and get his drugs. Do you open the doors when a smoke detector is triggered ? Then the kids smoking in the bathroom will trigger it. How many times does this happen before somebody disables the door release circuit ? And, unlike a chained door, a disabled automatic lock isn't apparent until the actual fire. Also, if the alarm bell fails, there are backups, like the PA system or even somebody running down the halls yelling "Fire !", but what backup is there for an automatic door that won't unlock ? StuRat (talk) 21:47, 3 March 2010 (UTC)

I'm sure it's illegal to chain the doors shut, but that won't stop people from doing so. There would need to be wide-scale random inspections and long prison sentences whenever a violator was found, to have any hope of actually stopping this. StuRat (talk) 21:01, 3 March 2010 (UTC)

Why precisely would they do it? You're assuming people are doing it without giving a legitimate reason for them to do so, particularly given the consequences of violation. You can't assume something bad is happening and then demand something be done. Prove your case. Give one example of a school currently using this practice. Myths like this about inner city schools are based in ignorance and racism. —ShadowRanger ^(talk|stalk) 21:05, 3 March 2010 (UTC)

I already gave a source, here: [11]. The consequences to the person who orders the door chained are probably nothing more than a slap on the wrist (unless they get caught in a fire, that is). They would do it to prevent criminal activity (with no money budgeted to hire guards), which is far more likely than a fire. It's hardly an ignorant, racist myth that criminal activity is a problem in inner city schools, do you really need me to find a source to support this, too ? Please stop being abusive. StuRat (talk) 21:15, 3 March 2010 (UTC)

The source you gave answers your question: there are random inspections, there are directives issued, there is public outcry for change, there are fines for non-compliance. I have to agree with others, you seem to have a preconceived idea of a problem and are asking us to either prove you wrong or somehow else argue about it and criticize public policy you disagree with. To answer your original question (again as others have) yes, fire-drills are scheduled to be somewhat convenient/minimize disruption/etc and yes, some places do not just dump the whole building outside for extended periods. Do you have any further science question about this topic? DMacks (talk) 04:35, 4 March 2010 (UTC)

Obviously, once it reaches the newspapers the problem will be addressed, at least for a while. The problem is all those cases that have so far avoided public scrutiny. The percentage of schools with illegally locked doors will reach an equilibrium in each area, with factors like widespread, truly random inspections and severe punishment for those who locked the doors (not a fine for the school) tending to move the percentage down. Also, kids who tell their parents and the press about it might help, too, but that only works if the locked doors are visually apparent. Automatic unlocking doors that would fail to open in a fire aren't visually apparent and thus such a method wouldn't work on them. Also, some time after a public outcry over locked doors, I'd expect the inspections to go down, and possibly be scheduled for specific dates, resulting in administrators illegally locking the doors again and only unlocking them on inspection days. Also, low safety and security budgets will lead to this cheap "quick fix". And yes, I do want more scientific info. What specific measures are taken to keep kids from the cold ? Where are these taken and at what times of the year ? I'd also like sources. StuRat (talk) 14:32, 4 March 2010 (UTC)

If kids were really standing for hours outside during a drill, then the folks running it are idiots incompetent. The purpose of a drill is not to make you stand outside in the cold, it's to get you familiar with the evacuation process. And if it's actually a fire, you're better off outside the building than inside it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:49, 4 March 2010 (UTC)

That would depend on the type of fire. In the example I gave earlier, of a waste-paper basket that caught fire when a ciggy was tossed in, was thoroughly extinguished, and is now sitting outside, filled with water; an evacuation could do more harm than good. Another example would be a pot of food that went dry and caught fire in the kitchen area, was immediately covered and extinguished, but set off the smoke detector anyway. I'd say that most fires are like this, with only a few escalating to life-threatening status. StuRat (talk) 14:39, 4 March 2010 (UTC)

The problem you seem to be missing is that by the time you've identified the cause, it's a bit late to evacuate if it's a serious fire. So that's why you don't do it. If the alarm goes off, you evacuate. Once you've identified the cause and determined it's safe, then you go back in. You don't wait until you know whether it's a serious fire before evacuating. Nil Einne (talk) 14:25, 5 March 2010 (UTC)

That's sometimes true, but a person is often present at the site of ignition, such as a cook at a kitchen fire. I was personally present at a "fire" where a waste-paper basket with a ciggy in it lit up, and saw the whole building being evacuated as a result (I was in the building, but somebody else was the witness to the start of the fire). StuRat (talk) 17:12, 5 March 2010 (UTC)

Yes but how do you relay this information in time to prevent an evacuation? And cancelling an evacuation that's in progress is likely to lead to confusion and may be even chaos and could easily cause injury. Also how do you establish a level of trust to ensure this information is reliable. E.g. what happens if someone maliciosly says the fire was only a minor thing? Or if two fires happen simultaneously (again particularly possible if it's malicious)? Or if someone misidentifies the cause of the alarm OR thinks it's out but isn't? No as I said before, the evacuation should start as soon as the alarm goes off, waiting until you find out whether it's a serious fire or not just doesn't work. Once a person entrused with the responsibility has verified there's no risk you can return to the building. Nil Einne (talk) 09:33, 6 March 2010 (UTC)

In some cases no smoke detector triggers, but they just follow a policy of fully evacuating the building when there is any fire. This is what happened in the waste-paper basket fire I've talked about elsewhere. The person who witnessed it fully extinguished it, and called the fire department, since we are required to report all fires. The FD then responded with 2 full ladder trucks, 2 ambulances, and two cars, and pulled an alarm to fully evacuate the building. I have to question whether this massive response was really the best use of resources, considering the risk of insufficient manpower and equipment if a real fire happened at the same time, elsewhere. StuRat (talk) 14:16, 6 March 2010 (UTC)

I don't know how things work in the US, but here in NZ if the fire alarm goes off (usually due to a smoke alarm) in any commercial building and I presume schools as well, you always evacuate, I presume it's mandatory. The fire service will come (an automatoic signal being sent went the alarm goes off) and checks out the alarm, if it's a false alarm they'll disable it. Most/all? buildings get one free call out per year, any further callouts will cost usually I believe NZ$1000 (although it may vary depending one the circumstances and I'm not sure if this applies to schools). This may not seem like much, but I'm pretty sure it's enough to ensure most buildings avoid false fire alarms. Of course I'm not saying it doesn't happen, you do see it resonably often (fire trucks and people standing outside) most commonly I assume it's mostly a false alarm (e.g. someone in the eatery burnt fish). Nil Einne (talk) 08:09, 4 March 2010 (UTC)

Fines for false alarms would tend to lower fire safety, by causing the building managers to disable the alarms to avoid further fines. StuRat (talk) 14:35, 4 March 2010 (UTC)

I don't think disabling the alarms is easy (remember these things automatically warn the fire station, if you try to fool around with them, there's probably a fair chance you'll end up sending off a warning) and it would likely carry a severe penalty (when caught by spot checks etc) and I've seen no evidence it's a regular occurance or a real problem. There's also the issue of mentality I guess. Perhaps in the US, the mentality is such that many managers would do such a thing and it wouldn't surprise me if you saw similar behaviour in Malaysia for example, but I suspect the mentality here in NZ is such that it doesn't happen that often. Also, I suspect the person who owns the building doesn't pay the cost in many cases anyway. If a restaurant sets off the smoke alarm due to burning fish, the restaurant pays. The owner isn't going to turn off the alarm, which other then the penalties involved, would likely affect their insurance because some tenant keeps setting off the alarm. Yes this may not apply to schools, but they aren't really a typical business in particular for any public school, there's likely a risk to the principals job if they pull off crap like that and in any case, there are likely plenty of people in the school who would be aware if this went on and they'll generally have the ability to get something done about it if they find out. Of course, this probably occurs with many commercial properties anyway in many cases the owner may be at arm's length from the management and if there are problems, with frequent false alarms, they'll expect the management to deal with it but if they deal with it by disabling the alarm, there's a far chance the owner isn't going to be pleased. Also it's not primairly intended to be a fine but a cost recovery exercise. Nil Einne (talk) 14:14, 5 March 2010 (UTC)

I think, rather than just giving them a fine, the fire department should work with the building owners, managers, and occupants to come up with a plan to keep the alarms functional, but also prevent further false alarms. I have an aunt who had an alarm go off every time she cooked, and I just moved the smoke detector further away from the kitchen, and the problem was solved. Of course, one could argue that this won't provide as quick of a warning of a fire that starts in the kitchen, but she was at the point of pulling the batteries out to disable it altogether, so my solution is certainly preferable to that. In a commercial setting, another option might be upgrading the ventilation system in a commercial kitchen to get smoke out of there before it builds to a point that triggers an alarm. StuRat (talk) 16:09, 5 March 2010 (UTC)

I'm sure they do, I never said they didn't. Even more so if they ask for this sort of help or there's an obvious reason/solution for the false alarms that can be avoided. For a related example [12] [13] [14] ([15]) mention reducing false or unnecessary callouts from a general standpoint. (Where is my building's nearest Communication Center?) & [16] suggest people contact them before doing trial evacuations and controlled fires to reduce the risk of unnecessary call outs. However it is ultimately the building owner's resonability and it's entirely resonable if you are incurring additional costs by causing frequent call-outs you should pay for it and this does provide an incentive for the people to actually fix the problem rather then ignoring it. Note that the New Zealand Fire Service is funded solely by insurance levies so it isn't even taxpayer money we're talking about here (not that I consider that matters). Nil Einne (talk) 09:33, 6 March 2010 (UTC)

Some of those links are a bit off topic, such as the policy on intentionally setting outdoor fires. I think resolving false alarms should be thought of as everyone's responsibility, not just the building owner, as they are more likely to just disable the alarm system than the occupants or fire department are. StuRat (talk) 14:03, 6 March 2010 (UTC)

You've still not cited a source that standing outside in the cold during a fire drill has made anyone sick. Comet Tuttle (talk) 17:29, 4 March 2010 (UTC)

Here's a chart showing that frostbite can occur in 15 minutes or less at -10F with only a 5 mph wind: [17]. I'd expect that even a fast fire drill takes about that long. Hopefully they avoid fire drills when it's that cold (although I'd still like a source with a policy on that), but that still leaves open the other part of my Q, how they deal with false alarms (and real fires) in cold temps to reduce this possibility. StuRat (talk) 18:05, 4 March 2010 (UTC)

Nice chart, but, again, you have not cited a source that standing outside in the cold during a fire drill has made anyone sick. I think it's laudable that you think that cost-benefit analyses are worthwhile, but I don't see a lot of evidence here demanding a reaction. Comet Tuttle (talk) 18:40, 4 March 2010 (UTC)

Well, it's circular logic to say that we shouldn't study hypothermia from fire drills unless we have proof that it exists from existing studies on hypothermia from fire drills. But what part of the logic chain do you doubt, exactly ? That fire evacuations happen when it's that cold or windy ? That they can last for 15 minutes ? Or that, as the chart states, this can cause frostbite ? Lacking any actual studies on hypothermia from fire drills/evacuations, the best we can do is to look at the components that would lead to hypothermia. StuRat (talk) 19:13, 4 March 2010 (UTC)

The part I doubt is your repeated implication that the adults supervising the kids are so clueless as to not use their common sense to deal with a cold day. If it is so cold as to actually cause frostbite in a few minutes' exposure, then any adult will find a way to deal with the situation. The kids are not being ordered to stand outside by some computer algorithm that hasn't the capability to deal with corner cases. I think your inability to cite sources for fire-drill injuries may be demonstrating that, yes, because of the presence of humans in the loop, there is no problem to solve here. Comet Tuttle (talk) 07:08, 6 March 2010 (UTC)

Many of the methods which could be used to prevent exposure would require pre-planning, such as blankets in a shed or having access to a building they can use for warming up (you can't just jam 1000 students into the nearest McDonalds). If there are no blankets, or the shed/building in question is locked and nobody has a key handy, it would be difficult to resolve these issues in the 15 minutes before kids start to suffer from the effects of the cold. That's why I asked for some indication that this is planned for, in advance, and wanted to know what type of planning they do for such a situation. There's also obviously a difference between drills, which can be skipped on bad weather days, and actual alarms, which can't, so different plans may be needed for each (such as "avoid drills when the wind chill factor is below X, and evacuate to the community center when an actual alarm goes off on days with a wind chill factor below Y"). Here's a letter from a parent pissed off at a cold weather fire drill: [18]. StuRat (talk) 13:47, 6 March 2010 (UTC)

When I was in high school, we did fire drills (and one actual fire) under cold-weather conditions: instead of evacuating outside, everyone evacuated to the semi-detached cafeteria. The building had been designed for exactly that purpose, with two firewalls rated for half an hour each between the cafeteria and the main school building. I expect that most schools in cold-weather areas have similar plans. --Carnildo (talk) 01:40, 5 March 2010 (UTC)

Thanks for that. You know, you're the first person to actually provide an answer to part of my question, rather than ask me to prove the assumptions in it ? Well done. StuRat (talk) 12:56, 5 March 2010 (UTC)

Of course it's not that hard to find actual references. For example a very quick search finds [19] says that a fire drill was delayed because of cold weather and [20] says students are allowed to pick up coats etc provided it doesn't take extra time. Of course there's also [21] and [22] which are complaints about fire drills in cold weather Nil Einne (talk) 14:33, 5 March 2010 (UTC)

Thanks for those. I still get the impression that they look at it solely from the POV of making students uncomfortable, though, and not an actual risk to their health. That part about only being able to get coats "if it doesn't take any time" seems a bit silly, as other fire regulations require that coats be stowed in lockers, which, of course, require time to open. The last two sources are also from students and a parent, but I'm still looking for some official policy saying "fire drills will not be conducted when the wind chill factor is below X". StuRat (talk) 15:56, 5 March 2010 (UTC)

Can you show the regulations relevant to Vineland that require coats be stowed in lockers? It's possible that other jurisdictions have such requirements, but it's not really relevant to Vineland if they don't. You can debate whether they should but that really seems to be getting OT. (In other words, they have these regulations which work for them, they may not work for everyone but of course there may never be a universal solution.) Of course the regulations on firedrills are from 1997 so it's possible they never bothered to update them if the regulations on coats in lockers are new. Nil Einne (talk) 09:16, 6 March 2010 (UTC)

A short, simple answer: Not from a school, because I'm a chief fire warden (house warden/building warden) in a high rise building housing a couple of thousand people - rather than a low rise school.

The process:

• Someone sets a kitchen microwave to two hours instead of two minutes
• Fire alarm goes off. Evacuation tone sounds on the affected area, on the floor above and the floor below. Three people on the affected floor know why the alarm is going off, but staff are very well trained to leave immediately in case of a fire alarm.
• Fire alarm goes off on the the next floor up and next floor down.
• Chief fire warden and team arrive at the fire control panel, attempt to contact the affected floor. Too bad, they've evacuated. Alarm panel shows three smoke alarms triggered, and five floors evacuated or evacuating. It's a very easy decision to evacuate the rest of the building.
• Everyone (except the chief warden team) gets to stand around in the cold waiting to be let back in, word filters around that the evac was caused by some overcooked chicken - smoke but no fire.
• Someone on the chief warden team gets to escort the fire fighters to the alarm floor (wondering whether there is a fire, and noting that s/he is the only person present not wearing fire proof clothing), they find a lot of smoke, but no fire, the microwave is warped and dead and is the obvious cause.
• the all clear is declared.

Sure there were people who knew what was happening, but IF YOU HEAR THE EVAC TONE YOU LEAVE BY THE NEAREST FIRE EXIT IMMEDIATELY, and happily break the glass on the break-glass-to-exit if the door isn't already open. Because building fires get very dangerous, very quickly. There was absolutely no chance of anyone being on the alarm floor by the time there is someone in the control room to ask what the problem is. It is very difficult for an evacuated person to get a message to the chief warden team before evacuation is ordered for the whole building.

Now if you scale that down to a single or double story building, alarms will generally trigger immediately in the entire building and people are able to evacuate out of several doors very quickly. There is absolutely no hope of someone checking and silencing an alarm before the automatic systems have gotten everyone out.

Would you want to slow the whole thing down so a human could get into the control loop sooner? I personally would prefer 100 unnecessary evacuations for each necessary one over no unnecessary evacuations and any real ones to happen only after a fire is well established.

And outside, freezing in a trial evacuation? I doubt it. I know we conduct our trials evacuations in late spring or early autumn.

Bomb threat? I personally would much rather be half a kilometre away from the building with the rest of the staff rather than being in the control room under the building in the case of a real bombing.

--Polysylabic Pseudonym (talk) 16:24, 7 March 2010 (UTC)

On the 2-hour cold weather bomb threat, I absolutely agree with the evacuation, but would argue that more of an effort should have been made to keep the evacuated students warm, and this probably requires planning in advance, which didn't appear to have happened, in this case. I disagree that 100 unnecessary evacs are fine, though, as human nature is such that when you "cry wolf" so many times, people start to ignore it. In this case it could either lead to people disabling the alarms/detectors or to them ignoring them when they go off. Now, as for how to avoid unnecessary alarms, that may need to be approached on a case-by-case basis. I was in a building that had a microwave catch fire in just about the exact same scenario as you described. Perhaps microwaves which only have a 5 minute timer are the answer (the person could always cook it a bit more if it's not done by then). (You could also ban microwaves entirely, but that would probably just result in people hiding them, possibly in closets full of flammable material.) StuRat (talk) 20:57, 7 March 2010 (UTC)

Is there a type of Bee/Wasp/Hornet that doesn't have a stinger?

A friend of mine mentioned this. He said it doesn't have a stinger, but it drops something on you that burns. And if you swat it on your skin, it leaves behind a residue that also burns. Does such a thing exist? ScienceApe (talk) 17:19, 3 March 2010 (UTC)

I've never heard of the burning substance part, but there are flies (no stinger) that mimic bees as a defensive measure. StuRat (talk) 17:25, 3 March 2010 (UTC)

The drones of many bee species lack a stinger, and other bee species (e.g. the mason bee) possess stingers but generally don't use them except when directly attacked (squeezed, stepped on, etc.), as they lack the territorial instincts of the honeybee. I don't know of any species with a contact venom. —ShadowRanger ^(talk|stalk) 19:07, 3 March 2010 (UTC)

Not a hornet, but see bombardier beetle (which is probably what your friend is thinking of) and perhaps assassin bug. Matt Deres (talk) 21:25, 3 March 2010 (UTC)

Perhaps your friend lived in ancient Canaan -- see here. DRosenbach ^{(Talk | Contribs)} 03:01, 4 March 2010 (UTC)

See stingless bee for stingless bees, but as MD says, your friend is likely talking about a non-bee. --Sean 20:58, 4 March 2010 (UTC)

anti-gravaton beam

In a surprisingly large number of Star Trek episodes the use of an "anti-gravaton beam" is employed to solve various problems; collapsing wormholes, disabling shields and deactivating mines to name but a few. What exactly is an "anti-gravaton beam"? Does such technology currently exist? —Preceding unsigned comment added by ShadowFire101001 (talk • contribs) 17:57, 3 March 2010 (UTC)

What is it? Nothing, it's completely fictional. The idea would be that a graviton would be a gravity-producing particle, so an anti-graviton would produce anti-gravity (a general repulsive force). You could use it to push things. Vimescarrot (talk) 18:00, 3 March 2010 (UTC)

Which in fact would clash with general relativity. The whole theory is hypothetical and has not even reached any mathematical formulation yet. _noisy jinx ^huh? 18:07, 3 March 2010 (UTC)

From Memory Alpha [23]

Anti-gravity refers to the state in which an object defies the laws of gravity.

I take this to mean that an anti-graviton beam is something of a MacGuffin. Subryonic compound (talk) 18:16, 3 March 2010 (UTC)

I personally like the idea of anti-gravity, emanating from galactic voids, pushing the galaxies apart from each other and also compacting each one together. This would explain both the observations that the universe is expanding at an ever-increasing rate and that galaxies seem to have insufficient mass to hold themselves together by gravity alone. This also relates to the topics of dark matter and/or dark energy. StuRat (talk) 18:16, 3 March 2010 (UTC)

I believe that in current theory, the graviton's antiparticle is also the graviton. So an anti-graviton would be sort of like "unobtainium". It's completely fictional, and so transparently so that you can ascribe any properties you like to it. APL (talk) 20:19, 3 March 2010 (UTC)

As transparent as transparent aluminum ? :-) StuRat (talk) 20:36, 3 March 2010 (UTC)

It can not be as useful as ejecting the warp core Googlemeister (talk) 21:50, 3 March 2010 (UTC)

When Dr. McCoy used one of his instruments to scan a person's body, the instrument he was using was actually a salt shaker. A subliminal message to take any preposterous-sounding technology with a few grains of salt. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:53, 4 March 2010 (UTC)

theory of relativity

Apparently Albert Einstine didn't invent the theory of realitivy he just modified an early theory. Is this true? Who was the original author? —Preceding unsigned comment added by Delvenore (talk • contribs) 18:09, 3 March 2010 (UTC)

Since you are the one claiming that such a theory existed, may be you should be telling us who did it. As far as I know there was not such a theory. Dauto (talk) 18:16, 3 March 2010 (UTC)

Perhaps you are thinking of the work of Lorentz? -- Coneslayer (talk) 18:17, 3 March 2010 (UTC)

Maybe these articles will help. History of special relativity / History of general relativity. --Mark PEA (talk) 18:19, 3 March 2010 (UTC)

I think Minkowski did some work on this stuff. —Preceding unsigned comment added by RubberBeaver (talk • contribs) 20:59, 3 March 2010 (UTC)

Einstein's work was indeed based (like all scientific theories) on the work of others. The general ideas that are contained in the theory special relativity are very similar to lines of thought being pursued by Hendrik Lorentz, Henri Poincaré, and others at the time. However, Einstein's work was in many ways quite different than both Lorentz's and Poincaré's. In retrospect, people go, "oh, it's the same thing!" mostly because they don't know how to distinguish them (e.g. why the Lorentz contraction is doing something different in special relativity than it is in Lorentz's ether theory), and because they have been sold a myth about how Einstein and science works, whereby a lone genius magically came up with a totally new way of seeing the world. Einstein had some really key insights, which he both derived from and merged with a lot of previous work. --Mr.98 (talk) 00:01, 4 March 2010 (UTC)

You might be talking about Galilean relativity. --Tango (talk) 04:57, 4 March 2010 (UTC)

The quote, which is attributed sometimes to Isaac Newton (its likely an old aphorism) applicable here is "If we have seen farther, it is because we have stood on the shoulders of giants." In other words, no scientist works in a vacuum. Every scientist, even the REALLY REALLY IMPORTANT ones, like Einstein and Linus Pauling and the like, makes incrimental progress towards increasing human knowledge. It may be helpful to think of each scientist adding some small % towards aligning our working models of the universe with the actual way the universe works. If the average physicist contributed like 0.01% towards improving the model, and Einstein was say 1000x more important towards that model than the average phycisist, he'd still only be contributing 10% of the total picture. So, he can still both one of the most important physicists in history, and STILL working extensively with the works of others. --Jayron32 16:37, 4 March 2010 (UTC)

"If I have seen a little further it is by standing on the shoulders of Giants." Buddy431 (talk) 06:50, 5 March 2010 (UTC)

Antimatter

Since regular matter emits regular gravity (in the form of gravitons), does antimatter, the opposite of regular matter, emit antigravity/negative gravity? --J4\/4 <talk> 18:18, 3 March 2010 (UTC)

The graviton is still a hypothetical theory, nothing more. _noisy jinx ^huh? 18:21, 3 March 2010 (UTC)

(ec) This might be better joined with the Q 2 questions back. Also note that the graviton is only a theoretical particle. StuRat (talk) 18:24, 3 March 2010 (UTC)

(ec)Antimatter has mass equivalent to the mass of its matter counterpart; an anti-proton weighs the same as a proton. As such, it has the same gravitational attraction as matter; it doesn't cause a repulsive effect. This has not been directly observed to date (we don't have enough stable anti-matter to make any such observations), but it is the overwhelming consensus of physicists. Handily enough, we have an article on it: Gravitational interaction of antimatter —ShadowRanger ^(talk|stalk) 18:28, 3 March 2010 (UTC)

Sunlight

Why does the sun make your skin dark but your hair light? —Preceding unsigned comment added by Transfigurations (talk • contribs) 18:45, 3 March 2010 (UTC)

The reaction with skin is with living cells whereas the reaction with hair is with non-living cells. 71.100.11.118 (talk) 18:56, 3 March 2010 (UTC)

Sunlight makes photopaper dark (even without chemical development). By your reasoning, does that imply it is living? Edison (talk) 18:59, 3 March 2010 (UTC)

Edson, I think if you look carefully you might spot the fallacy of your statement above. Dauto (talk) 22:12, 3 March 2010 (UTC)

The fallacy is in the explanation by 71.100.11.118, which I pointed out. Edison (talk) 19:57, 4 March 2010 (UTC)

This is not relevant to the OP but, since the question has been answered below, I'll post. 71.100 said that skin cells are living and hair cells are not therefore sunlight darkens skin while it lightens hair. Your post above implies that 71.100 said that sunlight darkens skin therefore skin cells are living. Note: 71's post was incomplete and unhelpful and inappropriate, but not fallacious. Zain Ebrahim (talk) 22:08, 4 March 2010 (UTC)

Sunbleaching (what, no article ?) has an effect on many objects with pigment, living and inorganic, by breaking down the pigmentation molecules, where the light stops, doing damage in the process. A suntan is a reaction to sunlight's UV damage to the skin, which causes the release of melanin, to prevent further damage. This is a protective measure more common in people with light skin, which allows them to get the sunlight they need to produce vitamin D when sunlight exposure is low (as in winter), and yet not develop burns and skin cancer when sunlight levels are high (as in summer). Those whose ancestors lived closer to the equator tend to have more melanin, and hence darker skin, since sunlight exposure is high there year-round. Why doesn't hair have such a protective measure ? It's dead (except for the follicle), so isn't susceptible to cancer or sunburn. StuRat (talk) 18:58, 3 March 2010 (UTC)

cause of exponential expansion of the universe

My studies have come to the conclusion that the Big Bang is the result of the polar force of gravity I call anti-gravity. This force is also the cause of the expansion of the universe and explanation why the universe is expanding exponentially in the presence of less gravity to slow it. However, I think this is original research and can not add it to an article. Could the reference desk please inform me if this is original research of if others have reached the same conclusion? 71.100.11.118 (talk) 18:48, 3 March 2010 (UTC)

If you can link us to your studies published in a peer-reviewed journal, and preferably to some secondary sources discussing the importance of your findings and how meaningful they are considered, then we can add it to an article. If you have none of these things, it is original research and cannot be added. If you have those things, I'd be surprised that you are trying to get it published in an encyclopedia: I'd have thought you have more research to do, papers to write, conferences to speak at, etc. 86.177.121.239 (talk) 18:57, 3 March 2010 (UTC)

Note that Wikiversity lacks Wikipedia's ban on OR, so your thoughts (which happen to be quite similar to mine) would be quite welcome there. StuRat (talk) 19:11, 3 March 2010 (UTC)

Done, thanks. Exponential expansion of the Universe 71.100.11.118 (talk) 21:05, 3 March 2010 (UTC)

Please don't add your ideas to Wikiversity. One can't usefully teach a subject that one doesn't understand, and you don't know the first thing about cosmology. I mean no offense. If you'd like to learn cosmology, I recommend Introduction to Cosmology by Barbara Ryden (ISBN 0805389121). -- BenRG (talk) 23:27, 3 March 2010 (UTC)

artificial intelligence

Have artificial intelligence reached the point where they are self aware yet? I've tried the current AIs and they always just seem to regurgitate random parts of conversations you had previously with them, they don't seem to think —Preceding unsigned comment added by Aject8886 (talk • contribs) 19:31, 3 March 2010 (UTC)

Definitely not. We don't even know how to do that in theory, as simply adding more processing power just leads to a more powerful calculator. And, if we could make a self-aware computer; should we ? There are many moral concerns, leading all the way up to the world of the Terminator movies.

Also note that we may someday be able to create a computer which passes the Turing test, meaning we can't tell if it's following a program or actually thinking. But, to me, this just means it's able to simulate intelligence, not that it's actually intelligent. Is it just a new and improved Magic 8-ball ? The answer is unclear at this time. StuRat (talk) 19:40, 3 March 2010 (UTC)

"Sentience" is an abstract like "Art". I don't see that there's a difference between a perfect simulation and the genuine article. APL (talk) 19:51, 3 March 2010 (UTC)

Or maybe it's more like stage magic. It's only real if you don't know how it works. APL (talk) 19:53, 3 March 2010 (UTC)

That seems to be a popular opinion. Personally I think it's nonsense. I know very well that I am sentient, though I can't prove it to you. Showing that a simulacrum had the same electrical patterns would not address the question at all. --Trovatore (talk) 22:30, 3 March 2010 (UTC)

I didn't address electrical patterns at all.

I'm saying that as an abstract concept I'm not convinced that there's a difference between "real" and "exactly like real, but not".

If Leonardo De Vinci jumped out from behind a curtain and said "Haha! Fooled you! All of my paintings were based on mathematical equations and tedious computations and no creativity at all!" would that immediately move them from the realm of "Art" to some new realm of "Fake Art"? Of course not. There's no such thing as "Fake Art", it's a meaningless concept. I'm no philosopher, but I honestly don't understand the difference between "Sentience" and "Fake Sentience".

(Note : I do, of course, understand the concept of a "soul" as some immaterial, but necessary, prerequisite for intelligence. But I do not believe this theory. ) APL (talk) 23:13, 3 March 2010 (UTC)

(After E/C with StuRat)

You're probably thinking of things like Megahal, and yes. Those are specifically designed to regurgitate past conversations in a vaguely believable manner. Done properly they can be very convincing for short conversations. To my knowledge there is no "Full AI" that even comes close to fictional AI's like HAL 9000. I don't think there's even a good chatter-bot that can keep up a long conversation in a logical way.

Most of the research into AI nowadays goes into either AIs designed to complete some specific task, or to autonomous AIs with much 'smaller' minds than you'd get in Science Fiction. The idea being to duplicate, say, an ant's mind before trying to simulator a human.

"Self aware" and "Sentient" are difficult terms to quantify. A more objective standard is the Turing Test. Many people argue that a computer that consistently passes the Turing test would only be "pretending", and using a complex set of rules to create its intelligence. (Personally, I'm not at all convinced that those of us with squishy brains aren't doing the same thing. The laws of chemistry are just as immutable as a computer's instruction set.) A more serious argument is that a computer that is smarter than a human would also fail the Turing test.

The Artificial Intelligence article is a bit of a mess, but there's still good information there, worth reading. APL (talk) 19:51, 3 March 2010 (UTC)

(ec)The "AI"s you've communicated with are likely variants on the ELIZA bot, which was never even intended as an AI, but rather as a limited natural language processor. Natural language processing would be required to create an AI humans could interact with a la Star Trek, and true natural language processing might require AI, but they aren't the same field. Mimicking the processing power of even a fraction of the human brain would require substantially more processing power than we are likely to be able to produce in the next few decades (at least without introducing communications delays between the components). We have no other model for AI besides the human brain, so unless there is a major leap in AI theory, we're not going to see a self-aware machine for a long time. —ShadowRanger ^(talk|stalk) 19:53, 3 March 2010 (UTC)

Computers have been self-aware for ages. Every time you ask how much disk space is available, the computer is telling you about its internal state. Self-awareness is by no means the hardest part of artificial intelligence, in fact it's one of the easiest. And it definitely isn't the same thing as "thinking". Looie496 (talk) 21:32, 3 March 2010 (UTC)

I don't think that counts. Even the simplest animals can respond to internal state. When you're hungry - you go and eat. Knowing whether you are hungry or not is a very basic thing. We could probably show that plants are self-aware in that sense. Self-aware means being able to perform introspection on one's own thought processes. The tangled mess that is the first paragraph of Self-awareness attempts to say something like that! SteveBaker (talk) 02:05, 4 March 2010 (UTC)

The problem here is that there isn't a test for "self-awareness" - how can you tell whether any person you bump into in the street is self aware? You can ask them "Are you self aware?" - but then the following one-line C program would pass that test:

   int main () { printf ( "Yes!  I am self-aware.\n" ) ; return 0 ; }

...so that's not going to work. We have no idea whether small children, dolphins, dogs, or ants are self-aware. It's possible that I'm the only entity in the universe that is self aware...and everyone else has a mindless ability to claim to be self-aware when I ask them...but you may have a different outlook than me!

As for AI, well, the business of building a truly intelligent system has really gotten nowhere since the 1960's. The AI community are attacking more tractable problems - things like linguistics, speech, visual recognition, knowledge representation - things that hover around the edge of actual intelligence. The Turing test will undoubtedly be passed - and probably not long from now - but serious AI researchers don't regard that test as anything particularly meaningful these days and the thing that passes it would seem remotely intelligent to careful investigators.

SteveBaker (talk) 21:50, 3 March 2010 (UTC)

Steve, may I lend you an "n", an aposthrophe, and a "t", so you can change your "would" to a "wouldn't" ? StuRat (talk) 21:58, 3 March 2010 (UTC)

As long as I'm picking Steve's nits -- that one-line C program won't compile. (Don't believe me? Try it.) --Trovatore (talk) 22:22, 3 March 2010 (UTC)

I did and it does. There's a warning about printf being implicitly redefined, but it works fine. Gcc version is i686-apple-darwin8-gcc-4.0.1. --Stephan Schulz (talk) 23:21, 3 March 2010 (UTC)

Whoops, you caught me speeding — I didn't try it. I assumed you had to #include "stdio.h" in order to use printf(). --Trovatore (talk) 23:46, 3 March 2010 (UTC)

GAh! I just ran this code (It compiled without warning here.) and now my machine claims to be self-aware! SteveBaker, WHAT HAVE YOU DONE?!? APL (talk) 00:06, 4 March 2010 (UTC)

But despite all this nit-picking, we don't think Steve's post was lousy, right ? StuRat (talk) 22:33, 3 March 2010 (UTC)

Interesting choice of words. Would you expect your letters and punctuation to be returned to you at some point in the future?

Yes, and I'll provide a stamped, self-addressed envelope for just that purpose. :-) StuRat (talk) 22:33, 3 March 2010 (UTC)

Testing a computer for self awareness is easy! It involves two colors of paint and a mirror. APL (talk) 22:28, 3 March 2010 (UTC)

The mirror test is an interesting experiment - but it's really meaningless when it comes to AI. I can't write a computer program that will pass the test in one line of code - but given a camera and a robot arm, I could probably do it in a few thousands of lines of code. Definitely not something that requires intelligence or sentience. SteveBaker (talk) 02:00, 4 March 2010 (UTC)

Yea, I know, I was joking. Similarly, animals that can be trained to pass the mirror test are not generally thought of as having passed it. APL (talk) 02:39, 4 March 2010 (UTC)

Actually, that'd be an interesting program. The "Mirror test" has many variants, a general solution that could not be fooled by non-mirror images wouldn't be entirely trivial. Adding in all the usual computer-vision headaches like lighting issues and shadows, could make it a real challenge. The end result still wouldn't be "intelligent" in any general sense, of course. APL (talk) 07:11, 4 March 2010 (UTC)

My own opinion, the problem of artificial intelligence is constructing a computer that has intent (or even the minor form of intent called desire). It's very natural for a living creature to form an intent - even the lowest life forms seek out food, light, and other necessities of life, and humans can form complicated intentions without batting an eye, but so far the best we can accomplish with computers is programming them to make choices based on human intentions we can't yet get a computer to have an intent of its own. it will be a bit scary when we can, I think: with other humans, and even with animals, we can assume that their intents are reasonably similar to our own, but god knows what a computer would want if it had the capacity to want something. --Ludwigs2 02:55, 4 March 2010 (UTC)

A Roomba has the intelligence of a grazing animal (without its sex drive) and makes less mess. Cuddlyable3 (talk) 03:25, 4 March 2010 (UTC)

not in the least. a roomba doesn't differentiate between what it does and doesn't suck up, it doesn't make decisions about where to go next, it doesn't choose when to vacuum and when to rest (except as it has been programmed to have logic forks, or as it is turned on or off). your average Amoeba has greater intelligence than a roomba. --Ludwigs2 03:34, 4 March 2010 (UTC)

What makes you think I posess an amoeba? A Roomba and its cousin the Trilobite navigate around obstacles in a previously unknown area. As the article notes, a Roomba decides when to seek out its energy supply. It can wail for your help if it gets stuck. Is your amoeba intelligent enough to help with the housework? Cuddlyable3 (talk) 04:57, 4 March 2010 (UTC)

I have to say, when I think of "Grazing animal" I think of a relatively intelligent mammal. I suppose you're thinking of some tiny and stupid invertebrate?

Even so, From the Roomba article "Roombas do not map out the rooms they are cleaning. Instead, they rely on a few simple algorithms such as spiral cleaning, wall-following and random walk angle-changing after bumping into an object or wall. " APL (talk) 07:11, 4 March 2010 (UTC)

The kind of "AI" that computer games give to life-forms in the virtual world is very crude compared to "real" AI - and I wish we could give it another name - but it can pass a kind of 'reduced' Turing test. It's perfectly possible in some of the better networked games to be confused by who is a human-controlled player and who is a computer controlled drone. Obviously, that fails miserably when you can talk to them - but for non-verbal stuff in a game world, it's sometimes hard to tell.

Anyway - one strategy for implementing this kind of thing is called "Goal Oriented Behavior" (GOB for short) - and this approach uses a hierarchy of goals and means to achieve those goals - with weightings that force some goals to be more important than others. For a typical first person shooter, the primary goal might be to obey some game-designer-issued "order", the secondary goal might be self-preservation and the tertiary goal might be to kill human players - balanced by another goal to keep the ammunition level in his gun above zero by reloading. So it's never going to leave the precarious catwalk you placed him on - even if he's gonna get shot if he doesn't - but if he's getting shot at then he'll prefer to go and hide behind the inevitable nearby crate than to stand there like some damned idiot shooting back at you with his super-inaccurate gun at a guy with 5 lives remaining and a couple of health-packs nearby! When he has ammo left, shooting you is more important than reloading - but when he's fired his last shot, he'll reload.

Seeking weighted goals is a good way to do "intelligence" on the cheap - and it's not surprising that Computer games, Amoeba and Roomba's all use it. However, it says nothing at all about sentience or self-awareness. SteveBaker (talk) 15:59, 4 March 2010 (UTC)

The flaw with the "mirror test" is that it sets up a test that's based on human concepts of what self-awareness is, and then concludes that anything that fails the test lacks self-awareness. That's a little like setting up an IQ test and if someone scores poorly they're assumed to be of low intelligence. All such a test really demonstrates is the ability of the subject to take that particular test. And individuals can react differently. Consider television. Some dogs and cats ignore it. Some react to the sounds of animals (their ears twitch or whatever). Others will watch the images. It occurs to me that the ones that watch the images would be the most likely to pass the mirror test, as they recognize there's something there. Animals that fail the mirror test might just not comprehend what they're seeing, or as someone pointed out earlier, since the "other" creature has no scent, the dog or cat doesn't concern itself with it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:52, 4 March 2010 (UTC)

I suspect that most cats and dogs see a series of flickering still images on the TV, similar to what I see when I turn the refresh rate down on my computer screen. Why would they be able to resolve faster refresh rates than us ? It was probably more important to them, in their evolutionary past, since they tended to hunt smaller animals that can change direction rapidly, and even a fraction of a second delay in detecting that change could cause them to lose their lunch and maybe their life. So, those cats and dogs that do see a moving image instead of a series of still images probably just have a slower visual processing speed, not more intelligence. Interlaced images might look even worse to pets, looking like a blurry double image. StuRat (talk) 14:10, 4 March 2010 (UTC)?

Dogs rarely get interested in TV's because they live in a world of smells. It doesn't matter that what they see looks like a dog and sounds like a dog - if it doesn't smell like one, it's not a dog. Period. SteveBaker (talk) 15:59, 4 March 2010 (UTC)

I disagree. They most definitely use sights and sounds, as they work on a longer range. They tend to use smells to "verify identity" at close range. Some dogs will react to a barking dog on the TV, by going up to smell it. Then, once they smell it, they determine that it's not really a dog after all, and ignore it. StuRat (talk) 16:13, 4 March 2010 (UTC)

The editor who talked about "intent" is onto it. A machine does what it's programmed to do, and nothing more, regardless of how sophisticated it is. We have only a smidgen of understanding of how the brain works. If or when we figure that out, then we'll have a clue of how to build a truly intelligent creature - a cyborg, or whatever you want to call it. But beware of the "intent" factor. If you leave out morals and conscience, you could end up with a creature that has ambitions to rule the world, or at least to kill its creator. This is a familiar theme, somehow. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:59, 4 March 2010 (UTC)

So would a self aware AI attempt to rewrite its own program? Googlemeister (talk) 14:15, 4 March 2010 (UTC)

Not necessarily. Do we try to rewrite our own ? I suppose learning might qualify as rewriting your own program. If so, how about an O/S that downloads new drivers to "learn" how to use new devices ? StuRat (talk) 16:01, 4 March 2010 (UTC)

You can train a Neural net program, which is kind of like that.20.137.18.50 (talk) 19:59, 4 March 2010 (UTC)

Some people do. See drug abuse, Gene therapy, immunization, Plastic surgery etc... Googlemeister (talk) 16:17, 4 March 2010 (UTC)

It might want to (just as some humans would wish to) - but that's not to say that it would be able to without doing something suicidally dangerous. The authors of a 'real' AI program would certainly want to defend against that possibility (unless they were doing some kind of strange experiment or other).

However, at some level, "rewriting" is the same thing as "learning" - and any AI would certainly need to be able to learn. Humans can rewire their neurons just by memorizing a new telephone number - but that doesn't give us the conscious ability to demand that neuron number 123,456 connect to neuron number 987,654 on demand. Similarly, the AI computer software would be able to add lines of Cyc code to it's database by memorizing a phone number - but would be unable to specifically compose a rule "(#$genls #$1-800-1234 #$PhoneNumber)". That's rather important because you wouldn't want some stray thought to cause it to write something like "((#$capitalCity #$France #$WibbleWibbleI'mATeapot)" and thereby firmly believe this to be a true fact from that point onwards. There is good reason why conscious thought can't do things like that. SteveBaker (talk) 17:00, 4 March 2010 (UTC)

anti-gravity and any violent explosion

Might not any violent explosion be a form of anti-gravity incantation or creation; a violent dismissal of gravity if you will? 71.100.11.118 (talk) 22:44, 3 March 2010 (UTC)

No. Explosions create force that can counteract gravity, but gravity is still in effect. Gravity is a relatively weak force though, so it may not assert itself noticeably (at a human scale of perception) at the moment of the explosion. —ShadowRanger ^(talk|stalk) 22:52, 3 March 2010 (UTC)

To cover my bases: Technically, I believe whatever just exploded will no longer have the same gravitational attraction to anything within the cloud of debris. Anything outside the cloud will still be attracted in roughly the direction of the center of the debris cloud's mass, but anything inside the debris cloud would experience a weaker pull, since the debris that was blown past them will attract in a direction opposite that of the remaining debris's center of mass. Of course, unless you're blowing up planetoids, the gravitational effects from the debris would be negligible; my explanation is just being pedantic. —ShadowRanger ^(talk|stalk) 22:57, 3 March 2010 (UTC)

Really technically ShadowRangerRIT you're assuming a spherically symmetric explosion which would be subject to Birkhoff's theorem (relativity), however if your explosion was large enough and wasn't spherically symmetric you would feel a gravitational effect outside of the radius of the explosion. ;)

But tbh your first answer was completely correct. Looked at in another way, if I throw a ball straight into the air, I'm not using anti-gravity, but giving the ball a momentum away from the centre of gravitational attraction. Likewise when I blow up a pack of C4, anti-gravity isn't manifesting, instead chemical (potential) energy is converting into kinetic energy which gives the particles a velocity great enough to overcome not just their gravitational attraction but also their electromagnetic attraction which in this case is stronger. To the OP check out Explosive material 82.132.248.99 (talk) 00:12, 4 March 2010 (UTC)

More or less why I used the term "...form of..." since the consequence appears to be more or less the same. In other words in an environment where gravity does not exist exterior to the explosion. Another situation where gravity is present exterior to the explosion for instance might be the center of a too massive Black Hole; the explosion resulting from an intolerable presence and resulting imbalance of gravity and its counterpart. 71.100.11.118 (talk) 00:56, 4 March 2010 (UTC)

As you wrote above, you're excited about this idea of an "opposite" of gravity, but there is no such force. See our Gravitation article. Comet Tuttle (talk) 01:30, 4 March 2010 (UTC)

LOLFDL... The chasm between the realm of what might be and the realm that is assumed to be based on Wikipedia article is profoundly demonstrated by your statement. 71.100.11.118 (talk) 01:41, 4 March 2010 (UTC)

What might be has nothing to do with fact or science or truth - if we wrote articles about what might be, this would be an incredibly useless web site. There might be pink piano playing Aardvarks hiding in caves on the dark side of the moon - but we're not going to write articles about that. SteveBaker (talk) 01:55, 4 March 2010 (UTC)

oooh, another bleak assumption that anything written about here is 100% certain and without err. 71.100.11.118 (talk) 01:58, 4 March 2010 (UTC)

No, but read scientific method. A hypothesis is only interesting if you have some evidence to show that it might be correct. Comet Tuttle (talk) 05:14, 4 March 2010 (UTC)

Is the aardvark really pink if it is not reflecting any light? Googlemeister (talk) 14:11, 4 March 2010 (UTC)

Yes. Definitely. It's axiomatic that pink aarvarks are pink. SteveBaker (talk) 15:42, 4 March 2010 (UTC)

I don't know why you'd consider a 100% correct Wikipedia to be a "bleak" outcome - perhaps you don't understand what an "encyclopedia" is all about. Certainly it's not the case that everything here is 100% correct - like any major piece of writing, it contains errors and important omissions. However, it most certainly is our goal that everything here be both 100% correct and 100% referenced back to reliable sources so that people can satisfy themselves that we are 100% correct - and so that they can spot things which might not be because they aren't properly referenced, and fix them. Hence, excluding things for which are false and those for which there are no reliable sources is important. That's not to say that we can't write about patently false things like Time Cube or Perpetual motion - so long as we provide reliable sources that explain that they do not exist. We can't write about pink piano-playing aardvarks because we have no reliable sources that say whether they do or do not exist. Whether they actually do exist is unimportant to an encyclopedia - if there is no evidence, we can't write about it. SteveBaker (talk) 15:42, 4 March 2010 (UTC)

But you can speculate and write about things for which there is no evidence simply by qualifying your comment or writing as such. Any encyclopedia which fails to recognize this obligation is indeed one that is bleak. 71.100.11.118 (talk) 02:48, 6 March 2010 (UTC)

Not in this encyclopedia you can't! We have very strict rules to prevent you from doing that very thing! No original research, No patent nonsense, No complete bollocks, There has to be evidence for everything you write here, Everything has to be notable, Speculation isn't allowed and Wikipedia is not...anything other than an encyclopedia - to name but a few! Specifically, our "five pillars" document says: "Editors' personal experiences, interpretations, or opinions do not belong here. Everything you write here is required to be referenced - meaning that it has to meet certain standards of evidence. If there is no evidence for what you are writing about then you most certainly don't get to write it - no matter what qualifications you use. This is an encyclopedia - not a work of fiction or a place to find random flights of fancy. If you find that 'bleak' then I pity your poor sense of the joy of having most of human knowledge at your fingertips. SteveBaker (talk) 04:03, 6 March 2010 (UTC)

What is leaching?

Please look at this. I put a link in the article which currently goes to a disambiguation page. None of the articles seem appropriate for the use since it's a process of nature rather than intentional.Vchimpanzee · talk · contributions · 22:48, 3 March 2010 (UTC)

I'd drop the link. It's a definition, not an encyclopedic topic per se. Maybe a link to wiktionary, but the term is relatively simple standard English and doesn't need to be linked. —ShadowRanger ^(talk|stalk) 22:50, 3 March 2010 (UTC)

Leachate is probably the closest article on the dab page, but it's about leaching from waste sites. The idea is the same, though. -- Flyguy649 ^talk 22:56, 3 March 2010 (UTC)

I see you fixed it. Thanks.Vchimpanzee · talk · contributions · 14:12, 4 March 2010 (UTC)

Reversing entropy

At the current level of technological advancement of human society in 21st century, is there the possibility that entropy could be reversed? —Preceding unsigned comment added by Crockadoc (talk • contribs) 22:52, 3 March 2010 (UTC)

With our current level of technological development? No. And in theory, never. It's the topic of a short story, The Last Question, but even the story is indulging in hand-waving speculation. —ShadowRanger ^(talk|stalk) 22:59, 3 March 2010 (UTC)

I added the title to the OP's question. Cuddlyable3 (talk) 01:42, 4 March 2010 (UTC)

Short answer: wait long enough. Long answer: it's equivalent to saying "is there a possibility that we could flip a fair coin x times and get heads every time?", where x is the amount of entropy you want to reverse (measured in the right units). If you try long enough, it will happen eventually, but there is no way of causing it. The concept of entropy really isn't part of science in the sense of the scientific method; it's a mathematical concept, with properties that can be proven by the H-theorem. This theorem basically says that lowering entropy is impossible unless whatever thing you want to lower the entropy of has been prepared in a very specific way beforehand (think of this as flipping a biased coin). Note that any process that prepares a system in such a way will inevitably increase the entropy of another system by at least as much as you are lowering the entropy of the first system. Also, if you're planning on "waiting long enough", you might want to see Boltzmann brain. 70.27.196.12 (talk) 03:40, 4 March 2010 (UTC)

This may be off the track a bit, but if you had a coin-tossing machine that would toss the coin in the identical way each time, wouldn't the outcome be predictable? Or are you assuming a human tossing it? ←Baseball Bugs ^{What's up, Doc?} carrots→ 07:25, 4 March 2010 (UTC)

I would assume he is assuming a theoretical Laplace coin of infinitesimal thickness , thrown by a spherical cow in a vaccum. --Stephan Schulz (talk) 09:59, 4 March 2010 (UTC)

... and locked in a box with a cat that is both dead and alive. Gandalf61 (talk) 11:16, 4 March 2010 (UTC)

Coin tossing is a chaotic process - tiny changes in initial conditions can make big changes to the outcome. But it's almost certainly possible to control the situation enough to get a reliable answer. There was a documentary on TV a while back about people who have trained themselves to beat the game of craps by learning how to roll specific numbers on a pair of dice with much higher than usual reliability - it's entirely possible that someone could learn to toss a coin reliably too. However, in conversations of this sort, we're definitely talking about an idealized, utterly random binary outcome. Coin tossing is the spherical cow in a frictionless vacuum of the world of statistics. SteveBaker (talk) 15:17, 4 March 2010 (UTC)

It was a metaphor. I said fair coin for a reason. I guess I should have made it a link the first time, but a fair coin is no more a real coin than a cow is spherical and frictionless. 76.67.78.86 (talk) 02:52, 5 March 2010 (UTC)

You can easily reverse entropy locally. Take a box full of kiddies building blocks - carefully sort them by color and size and pack them neatly away in their box - and the entropy of the box has been reduced. However, it took energy to do that - or to state that scientifically: the low-entropy cornflakes that you ate for breakfast this morning got turned into higher entropy poop + high entropy heat. The overall entropy of the universe got a bit higher, the entropy of your breakfast got a lot higher and the entropy of the bricks in the box was lowered. We don't have any idea how to reduce the entropy of the entire universe - or any "closed system" for that matter (and it's very likely that this is totally impossible) - but we reverse entropy locally on a daily basis. SteveBaker (talk) 15:10, 4 March 2010 (UTC)

I once saw a video on youtube exemplifying laminar flow, but instead of linking that here, here's a description of it: http://www.fas.harvard.edu/~scidemos/NewtonianMechanics/ReversibleFluidMixing/ReversibleFluidMixing.html That isn't at all a counterexample of any law of thermodynamics, but it's a pretty neat and counterintuitive thing to see. 20.137.18.50 (talk) 20:08, 4 March 2010 (UTC)

There are several youtube videos showing this, this one is probably the best. It's truly an amazing thing. Strongly counter to daily experience! SteveBaker (talk) 04:14, 5 March 2010 (UTC)

Warp Drive

Is warp power in Star Trek based on actual technology or is it all made up? Does such warp drives theoretically exist? —Preceding unsigned comment added by Velderon4 (talk • contribs) 23:05, 3 March 2010 (UTC)

I'd suggest reading the article on the Warp drive. Short answer: No, there is no existing technology like that, but there are certain theories that might allow for something like it, but it's purely theoretical. —ShadowRanger ^(talk|stalk) 23:16, 3 March 2010 (UTC)

( After e/c with ShadowRanger)

Warp Drive is not really based on any real theory.

The closest I've ever heard of is the theoretical Alcubierre drive. Needless to say it has a variety of practical problems. APL (talk) 23:18, 3 March 2010 (UTC)

The warp drive is a very useful device for telling stories in outer space, and after having read the Alcubierre drive article, it sounds like that's about all it is. Vranak (talk) 23:33, 3 March 2010 (UTC)

Warp drive is as real as backwards time travel, using salt shakers as medical equipment, and experiencing deja vu. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:59, 4 March 2010 (UTC)

Are you suggesting that deja vu doesn't exist? Because I've certainly experienced it, and the article accepts it as a real phenomenon (although one hard to induce under laboratory conditions) Buddy431 (talk) 05:40, 4 March 2010 (UTC)

That was a subtle hint that this question is similar to another one on the ref desk, asking if some fictional technology is for real. And all three things are "real", just not in the same way. ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:47, 4 March 2010 (UTC)

These[24][25] to name two. There's a discussion on the ref desk talk page about these questions from what could ba a series of socks or maybe just some kids fooling around. ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:51, 4 March 2010 (UTC)

... But it's not deja vu if you've literally read the same thing twice! Deja vu is when you have (Or feel that you have) two memories of an event that you know only happened once! And I'm sure that this question hasn't only happened once. APL (talk) 05:57, 4 March 2010 (UTC)

In any case, there's a group of users that are asking similar questions, basically whether Star Trek is "real". ←Baseball Bugs ^{What's up, Doc?} carrots→ 06:02, 4 March 2010 (UTC)

An antimatter powerplant on the other hand would probably work great, the big problem is getting the fuel. Rather the biggest problem. Isolating your fuel would also be difficult. Googlemeister (talk) 14:09, 4 March 2010 (UTC)

March 4

In-text and Reference Citation for websites and textbooks

I'm aware of how to do in-text and reference citations for papers. But what is the format for websites and textbooks? —Preceding unsigned comment added by 142.58.132.87 (talk) 00:14, 4 March 2010 (UTC)

Usually questions about how to use Wikipedia belong at Wikipedia:Help desk rather than the Reference Desk, but I'm going to backstab us by answering: See Template:Cite web and Template:Cite book. In general the Template:Citation template is going to be flexible enough for anything at all, if you choose to read through the bazillion options. Comet Tuttle (talk) 00:28, 4 March 2010 (UTC)

If you are asking about how to cite things in your own papers (not on Wikipedia), it depends on the citation style you are using. (And for some styles, there simply is no official way to do it.) --Mr.98 (talk) 01:10, 4 March 2010 (UTC)

It's the same format as on paper. Why would it be any different just because the pages are digitized. —Preceding unsigned comment added by Telijelly (talk • contribs) 13:55, 4 March 2010 (UTC)

There are LOTS of reasons why it would be different in a digital world - for one thing you can have active links. You don't really need all that stuff about authorship, publishers, dates and page numbers when a single mouse click on the reference will magically teleport you to the actual document being cited. SteveBaker (talk) 14:45, 4 March 2010 (UTC)

That's fine until the target document moves or is deleted, which happens a lot online: then detailed bibliographical data becomes essential. --Normansmithy (talk) 14:51, 4 March 2010 (UTC)

That's why the DOI system was introduced - theoretically, as long as the document exists somewhere the DOI should resolve to the URL. —Preceding unsigned comment added by 131.111.185.68 (talk) 16:42, 4 March 2010 (UTC)

euthanasia

• Though several people have commented in good faith on this discussion, it appears that the original poster is more interested in either starting a debate or promoting a particular belief. Neither is appropriate for the reference desks. I am proactively closing this discussion down. If anyone is interested in the topic, we have articles on Euthanasia and assisted suicide for further reading. Other discussion should happen at some other website. Just not here. --Jayron32 21:21, 4 March 2010 (UTC)

This discussion has been closed. Please do not modify it.
The following discussion has been closed. Please do not modify it.
If it were an animal suffering from a severe illness people would say to put it to sleep because it was the humane thing to do. However, why must a human suffer because people are unwilling to do the “humane” thing and let them die with dignity so their suffering may end. —Preceding unsigned comment added by Thekiller35789 (talk • contribs) 00:42, 4 March 2010 (UTC) See our articles euthanasia and voluntary euthanasia. The latter says, "As of 2009, some forms of voluntary euthanasia are legal in Belgium, Luxembourg, the Netherlands, Switzerland, and the U.S. states of Oregon and Washington." The article has links to more specific articles, like Euthanasia in the Netherlands, Euthanasia in the United States, etc. Comet Tuttle (talk) 00:58, 4 March 2010 (UTC) The real meat-and-potatoes can be found in Voluntary euthanasia#Reasons given against voluntary euthanasia. Vranak (talk) 01:15, 4 March 2010 (UTC) was it by any chance a video of a blind dog that made you ask this? I thought exactly the same thing. All the comments were "do the right thing" and it struk me too how if that was a person, no one would say that. Vespine (talk) 05:05, 4 March 2010 (UTC) There are many excellent arguments in favour of voluntary euthanasia and assisted suicide, but I don't think the claim that it would place humans on the same eithical footing as animals is going to be one of the most persuasive. After all, we eat animals, but that is hardly an good argument for cannibalism, is it ? Gandalf61 (talk) 09:37, 4 March 2010 (UTC) Well, we don't generally claim that we're eating the animals for their own good. We do make that claim for euthanasia. -- Coneslayer (talk) 13:54, 4 March 2010 (UTC) We are not really killing the blind dog for his own good, we are doing it for our own convenience, and just deluding ourselves so we feel better. Googlemeister (talk) 14:06, 4 March 2010 (UTC) I'm not familiar with the "blind dog" video referenced above, and the OP didn't ask about blindness specifically. I was thinking of illnesses that cause pain, inability to eat, etc. -- Coneslayer (talk) 14:13, 4 March 2010 (UTC) We recently had to euthanise ("kill") our dog because at 12 years old, she developed a lump and started to be very slow and lethargic. She turned out to be riddled with cancer. With no way to complain, she'd probably been in considerable pain for six months or more - but as our vet said "Dogs are amazingly tough - they soldier on gracefully under the most crippling pain - but when they give up, they give up entirely." A serious effort to treat her would have cost $10,000 which we simply don't have and couldn't borrow - and would probably have only maybe a one in ten chance of working anyway. Unlike human hospitals, vetenarians don't work for free - even in emergency, life-threatening cases - and the government doesn't provide ultimate fallback health care for dogs. Because neither us nor our vet speak fluent dog - it would have been completely impossible to know whether "end of life care" (painkillers) were sufficient to provide a comfortable (albeit lingering) end. So after some debate, we paid the vet extra to come to our house, we carried the dog to her favorite spot in the back yard (she really couldn't walk anymore), settled her on her comfy dog-bed, gave her some of her favorite tit-bits (which she didn't eat) and then the vet shot her full of a strong sedative. When she fell asleep, an overdose of muscle relaxant killed her within maybe 30 seconds by stopping her heart and breathing. After we'd shed some tears, the vet took the body away for disposal. Not a bad way to go, all things considered. After a few months, we grabbed a 7 week old puppy from the animal rescue center. The old dog died after a good life and one less puppy had to be euthanised at the rescue center - a net win for dog-kind in general. It's amazing how much the act of repeatedly cleaning dog poop off your living room carpet and finding your best leather shoes reduced to 3cm x 3cm pieces all over the bedroom floor helps you get over the loss of an old friend. However, for humans who are suffering like that we have the financial support to at least make an effort to cure serious diseases and failing that, we can generally interact with the patient to give them at least some measure of relief from pain in a hospice-like setting. There is still a case for euthanasia ("killing") people who have had enough and are able to clearly say so - but there are certainly legal and ethical hurdles - as our articles indicate. It is unlikely that the loss of an adult due to some terminal disease will result in a family adopting a child as a replacement...and children that are not adopted are not routinely executed by the government. So there is zero comparison between the two circumstances. SteveBaker (talk) 14:42, 4 March 2010 (UTC) there certainly is comparison, its not all about what the family wants either. if a person lives alone and has no family. if they are blind, paralyzed , in severe pain and allergic to opiates. they should have the right to be killed. —Preceding unsigned comment added by Thekiller35789 (talk • contribs) 15:01, 4 March 2010 (UTC) Euthanasia is less the right to take your own-life than it is the right to allow someone else to take your life for you. Be that the state, a relative, a doctor or whoever. Allowing it introduces risks. Risks of systematic abuse, risks of misunderstandings, risks of coercion. On the face of it the idea of allowing euthanasia feels reasonable, feels like a good idea. Thinking through the logical and potential reality is where I (just my opinion) find it gets much more 'grey' and difficult. The key obstacle I believe is whether any party involved will be able to make a fair judgement. Relatives might want to put someone out of their misery because from the outside looking it that sort of a 'non existence' looks miserable, but what if that person doesn't want it but cannot say? What if the person said 10 years ago "if i'm in this position kill me" but once they're in the position they realise they want to live but cannot say? It's really not anything like as simple as you (thekiller35789) are seemingly making it. It's an incredibly complex issue with (for me) compelling arguments on both sides. ny156uk (talk) 17:11, 4 March 2010 (UTC) The OP persists in using this Ref. Desk to argue their support for euthanasia viz. "a person..should have the right to be killed". The question "Why must a human suffer?" finds varying answers within various belief systems and is therefore unanswerable neutrally. The OP uses a rhetoric device to fill the vacuum of that unavailable answer with their loaded contention "because people are unwilling to kill them". The underlined action is what is meant but the OP does not admit that. Instead the OP substitutes the weasel worded advocacy "do the "humane" thing and let them die with dignity". That prevarication assumes meanings of humane and dignity that only advocates of euthanasia apply in this context. "Let them die" is a transparent euphemism for kill which by definition is to prevent a life running its natural course. Claiming a justification for the killing to be "so their suffering may end" is direct advocacy of euthanasia. The OP's tendentious question is already handled by the Wikipedia reference that Vranak provided. This section should not be held open for the on-going debate that the OP seeks. Cuddlyable3 (talk) 21:07, 4 March 2010 (UTC)

Vectors

It's my understanding that, in order to prove that some quantity with direction is a vector, one must show that it is commutative and rotationally invariant. First question: are these the only two criteria? Second question: I've been able to show that the angular velocity vector is commutative, but how would I be able to show that it's rotationally invariant. Finally, how would one show that torque is a vector. Since torque is just a cross product of two other vectors, I quess this would reduce to proving that the cross product of two vectors produces a third vector, but I haven't been able to find a proof of this online. Thanks! —Preceding unsigned comment added by 173.179.59.66 (talk) 04:32, 4 March 2010 (UTC)

I'm sorry, but nothing that you wrote there makes any sense. Vectors are neither commutative (only operations can be commutative) nor rotationally invariant. The fact that the cross product of two vectors produces a vector is obvious from the definition of the cross product. I'm afraid that you're so far from understanding what you're doing that you might have to go back and relearn the basics of what a vector is. Looie496 (talk) 08:07, 4 March 2010 (UTC)

1) Sorry, I meant commutative under addition. 2) How can a vector not be rotationally invariant? That would mean an equation like F = ma would depend on the choice of axis. 3) To my knowledge, the cross product is defined as a determinant of some sort. The result of this computation produces something of the form ai + bj + ck, but that doesn't mean it's a vector.173.179.59.66 (talk) 08:35, 4 March 2010 (UTC)

Looie is right. What you are talking about is usually refered to by physicists as covariant under rotations. The Vectors are covariant under rotations and the vectorial equations are invariant under rotations. Dauto (talk) 19:42, 4 March 2010 (UTC)

That's funny, because this entire time I was mixing covariant and invariant, really sorry about that! —Preceding unsigned comment added by 173.179.59.66 (talk) 20:25, 4 March 2010 (UTC)

Have a look at http://en.wikipedia.org/wiki/Vector_%28geometry%29#Vectors.2C_pseudovectors.2C_and_transformations . The components of vectors should transform like coordinates under rotations. It is my understanding that a cross product is actually a pseudovector but don't quote me on that. —Preceding unsigned comment added by 157.193.173.205 (talk) 08:31, 4 March 2010 (UTC)

I think you should close this question and ask it again on the math reference desk. Those guys will nail this one very quickly. SteveBaker (talk) 14:12, 4 March 2010 (UTC)

Something doesn't need to have direction to be a vector. The definition of a linear vector space is http://en.wikipedia.org/wiki/Vector_space#Definition Basically the space must have closure, it must be distributive in the scalars, scalar multiplication must be associative, Addition must be commutative and associative, there is a null vector and an inverse under addition for each vector. For instance operators can be treated as vectors.

On another point vectors can be commutative, in a space of Real vectors all vectors are commutative because < A | B > = < B | A > * = < B | A >

82.132.248.82 (talk) 23:13, 4 March 2010 (UTC)

Who can make the definition of "Space" understandable to users with a high-school education?

I have chased down every (blue) referenced term in both the Space page and across numerous pages in a vain attempt to gain an understanding of the true understanding of the nature of 'space'. I accept the mathematical assumptions made in much the same way as a theoretically dimensionless point is defined for the purposes of function and equation. However, the original "Space" page left me with no descernable improvement in my understanding of both the existential nature of 'space' nor the efficacy of the many clumsy analogies that are proffered in support of meaning. I have read much of the arguements regarding the nature of 'expansion' with reference to space and the balloon analogy is a case in point: To declare that the balloon represents the expanding Universe and then stick an ant on the outside to argue that its corporal structure is unaffected by the expansion of the balloon universe is not helpful. The balloon analogy only works when assuming that the Universe is represented by the balloon; to add an ant (on the outside) is to break the very conventions of the analogy itself by introducing an ant (presumably) outside the Universe!

What would help users like me (and there are many - I assure you) is a comprehensive AND comprehensible explanation of the fundamental nature and function of space in both its physical and theoretical applications. For instance:

1. If space is a vacuum, or a volume in which nothing exists; how does gravity bend it?
2. If space is truely a state of non-existence, a vacuum within which nothing exists; surely this definition is based upon the attribute of 'existence' being the sole property of matter, as theories abound of zero-point quantum energy fields and some empirical evidence to support the idea that the Universe is filled with energy in all manner of modes and quantities, etc.
3. If space is merely a mathematical species of frames or matrixes that provide quantative relevence to various behaviors and transformations at macro, micro and quantum scales - what really causes space lensing??
4. The elevated circles within which the aether was argued and eventually discarded were not successful in transmitting a truely understandable analogy of this conclusion to the satisfaction of those of us that work with the real Universe. Such ideas may be erroneous but they are also intuitive - to existing generations as well as to our venerable ancestors. Wikipedia is at its best when it conveys to the masses a wholesome and digestible explanation of these endemic misunderstandings.

Finally, quantum physics has introduced us to the concepts of granularity and "forbidden states" that lie between manifest energy levels at sub-atomic scale; however, (in my clumsy attempts to consolidate their analogies and explanations) space appears to be devoid of any such constriction. We are left to ponder such (intuitive) conundrums as:

1. Is space confined to a resolution that must obey quantum rules?
2. Can string-theorists simply magnify the dimensions of particle physics by a billion and claim to have discovered a true and final base for the smallness of things?
3. Does matter really move; or does it simply emerge, first in a quantum spacepoint (A), then sink back into the quantum sea only to manifest again in Spacepoint (B) - that just happens to be the adjacent location closest to (A) - thereby giving the illusion of motion yet simply being a series of manifest existences bounded by the granularity of space; time; and energy/matter?

Scientists have done a wonderful job of improving upon the once clumsy definitions provided for the concept of "Energy" in this Wikipedia; I hope that a comparable attempt will be made to de-mystify the nature of "Space".

GPCViriya (talk) 09:46, 4 March 2010 (UTC)

Wow, that's a lot to take on. Let me just answer one small part of it by saying that space is not a pure vacuum. It certainly contains small densities of ordinary matter, and quite possibly other forms of matter such as dark matter. StuRat (talk) 13:53, 4 March 2010 (UTC)

OK - well, let me try to answer some of these:

1. If space is a vacuum, or a volume in which nothing exists; how does gravity bend it? - In general relativity, matter bends space and bent space produces the illusion of gravity. That's only one view, but it's the prevailing one. Why matter bends space is probably an unanswerable question. It just does.
2. If space is truely a state of non-existence, a vacuum within which nothing exists; surely this definition is based upon the attribute of 'existence' being the sole property of matter, as theories abound of zero-point quantum energy fields and some empirical evidence to support the idea that the Universe is filled with energy in all manner of modes and quantities, etc. - Space (as described by physicists and cosmologists isn't the same thing as 'vacuum'. It's kinda like the sheet of paper on which a diagram is drawn. The diagram is matter and energy - the paper is "space". It's the underpinning of what we perceive as "distance" or "position". The physicists concept of "space" is present even inside solid bodies. Now, if we're talking about "space" as (say) an astronaut might talk about it (the gaps between solid things that's mostly vacuum) then that's really something different. The "vacuum" of deep space isn't really empty - there are a few atoms per cubic meter, also lots of photons and all sorts of other exotic things like virtual particles.
3. If space is merely a mathematical species of frames or matrixes that provide quantative relevence to various behaviors and transformations at macro, micro and quantum scales - what really causes space lensing?? - Gravitational lensing can be thought of as the consequences of bent space (see question (1), above). Space is bent - light takes the shortest path through it and the shortest path across a bent surface isn't a straight line (kinda like aircraft flying long distances across the Earth travel along "great circle" routes because they are less distance than "straight lines"). To our senses - which can't directly comprehend the curvature of space, the light appears to bend.
4. The elevated circles within which the aether was argued and eventually discarded were not successful in transmitting a truely understandable analogy of this conclusion to the satisfaction of those of us that work with the real Universe. Such ideas may be erroneous but they are also intuitive - to existing generations as well as to our venerable ancestors. Wikipedia is at its best when it conveys to the masses a wholesome and digestible explanation of these endemic misunderstandings. - The aether theory was just wrong. It's a discarded hypothesis because it simply doesn't fit the facts. It may be intuitive - but it's a useless explanation because it doesn't explain the behavior of light.

Quantum physics questions:

1. Is space confined to a resolution that must obey quantum rules? - There is a minimum unit of distance which (I suppose) you could think of as the "resolution" of space.
2. Can string-theorists simply magnify the dimensions of particle physics by a billion and claim to have discovered a true and final base for the smallness of things? - No. String theory is much more complicated and radically different from the 'normal' view of particle physics.
3. Does matter really move; or does it simply emerge, first in a quantum spacepoint (A), then sink back into the quantum sea only to manifest again in Spacepoint (B) - that just happens to be the adjacent location closest to (A) - thereby giving the illusion of motion yet simply being a series of manifest existences bounded by the granularity of space; time; and energy/matter? - No, matter moves.

SteveBaker (talk) 14:08, 4 March 2010 (UTC)

Regarding the balloon analogy: the surface of the balloon is analogous to space. As the balloon inflates, the surface expands. The ant represents a point (or a set of points near each other) on the surface of the balloon. Zain Ebrahim (talk) 14:17, 4 March 2010 (UTC)

It may be easier if you don't think of matter as something that's "in" a vacuum, but rather think of it as part of the nature of the vacuum. If you look at general relativity by itself, without any matter, it's still a highly nontrivial theory—you have gravitational waves that propagate around and interact with each other, just like any other kind of wave might do, even though there's nothing "in" the space. In the Standard Model of particle physics, which is the best current theory of everything other than gravity, everything other than gravity is like this too. The "particles" are various kinds of oscillations of the vacuum. This is enshrined in the Standard Model in a fairly deep way, through the concept of spontaneous symmetry breaking. The nicely symmetric fundamental vacuum state of the Standard Model is unstable, so, at low enough energies, the vacuum ends up in a different, stable state at some "distance" (in the landscape of possibilities) from the center of symmetry. The particles of everyday life are small oscillations around that state, and they're only indirectly related to oscillations around the unstable center. When particle physicists say "vacuum", they mean a small neighborhood of an equilibrium state, or, in other words, the vacuum proper and all of the low-energy particles and their interactions. For example, when they talk about a "landscape of string vacua" and trying to find a vacuum that corresponds to our world, that's what they mean.

At least this means we don't have to understand space as a container for matter; we only have to understand it as a thing unto itself. Unfortunately, that's the best you're going to get right now. Space behaves like a multidimensional continuum that can be deformed in various ways, and nobody knows anything more than that. There have been many extremely speculative attempts to give it another structure, which go by the name of pregeometry. Probably the best developed of those ideas is spin foam, about which I know nothing beyond what's in the Wikipedia article. -- BenRG (talk) 02:37, 5 March 2010 (UTC)

Thank you,
(StuRat): You are saying that space is seldom (or ever) found in a pure state of vacuum; however, I understand that matter - ordinary, dark or exotic is not included in the definition of the nature of space, it simply exists at a certain point in space, manifesting its own family of characteristics and behaviors. Therefore, you are describing vacuum as a condition relating to the ratio of matter to the volume of space - not describing the fundamental nature of space (in itself).

Thank you, (SteveBaker):

1. The unanswerable question, (as how matter bends space) does not eliminate the underlying arguement of my question. My premise was; presuming that space (in its own nature) has no attributes, how can any thing bend it? When one refers to the change in shape (from flat to bent), under the influence of gravity; it is assumed that space (itself) has been influenced by the proximity of matter, which possesses an attribute of mass, which manifests a force called gravity, and has deformed space to reflect the influence of this force upon the very fabric of space.
2. Your comments (in 2) address my question in point 3. I assume that by paper, you mean physicists rely upon the paper to illustrate the positions and/or co-ordinates occupied by particles within a certain arrangement in space? This accords with my own understanding - that space is used as a foundation for the deliniation of such properties as; position, motion, etc. These properties are not ascribed to space, but to the particles, etc,. that are included in the diagram. Your extra comments regarding the condition of inter-stellar space returns to your earlier comments regarding the nature of a vacuum and do not directly address the nature of space.
3. In 3, you return to the point, that space is bent and light takes "the shortest path through it" thereby attributing some characteristic to space that is both bent and exerts an influence upon light to respond to this condition by following a bent path. However, this characteristic of space is left undefined albeit your contention that, whatever it is - it is bendable.
4. I presume that you are referring to the particle/wave characteristics of light when you mention that the aether hypothesis has been proved wrong. I have no arguement with this; however, it does help to illustrate my point regarding the unintended confusions created by using analogies that do not eliminate the underlying inference for just such a medium. By this, I mean; any and all mention of bent-space has the immediate effect of creating the idea of space as a thing, or medium within which the behavior of particles, under certain conditions, can only be explained by pertubations or deformations in the fabric of that space, medium or thing. Creating a vacumm to demonstrate the passage of light without the support of a medium does not eliminate the possibility that space, itself, has the characteristics of a medium. Simply removing all other particles from a region in space does not change the nature of the space itself. A vacuum is not devoid of space any more than the volume contained within the body of a sub-atomic particle is devoid of space, regardless of its mass.
5. To my quantum physics questions, you peaked my interest when you mentioned the existence of a theoretical minimum distance; then you simply discounted any significance to this assertion when you stated that "matter moves". Clearly both cannot be right. If matter was required to move only a fraction of the "minimum distance", it could not - then we would have to deal with all the potential and/or kinetic energies that may still require transition. If the matter was to move only 1 unit of the minimum distance; it could only achieve this (not by an analogue re-positioning) but by a cessation of existence in one location and a subsequent manifestation at the next, or nearest location (as any smaller movement would be prohibited).
6. String theory may appear to be more elaborate and complex than particle theory, but it still must address the fundamental characteristics that have been thus far observed. In essence, (to the ear of a layman like myself); string theory has replaced the elementary particle with a field of strings, at a greatly reduced magnitude in both scale, momentum and inertia, and used the more numerous unique characteristics of a string (as opposed to a particle) in their analogies - to ascribe the various configurations and resonant conditions in the stings to represent the observed momentums and behaviors of higher species of elementary units.

I am in no position to question the verasity of the science, experimentation, and theoretical conjecture that is contained in either the Standard Model nor the fledgling String Hypotheses; however, neither side has provided the general population with any working analogies that withstand even the most precursory analysis. Although such examples are not meant to explain the complete picture; they actually pollute the mind of the thinker when these analagies are pushed too far.

Zain Ebrahim's opening comment is a case in point: Given that the analogy of the balloon is representative of the fabric of space and its inflation indicative of the effects of expansion: the ant may represent either a point, or several points in the aforementioned space. Assumed to be a point - the ant experiences no change; as a point is considered to be dimensionless and therefore immune to any change in scale happening around it. Assumed to be a collection of points where the feet touch the surface of the balloon - the ant will find its feet becoming ever more widely spread the longer the expansion of the balloon continues. These are necessary considerations that require the layman to first accept that an ant, outside the balloon, is still in the Universe that has been defined as the surface of the balloon. In fact, we need to discount both the volume of air within the balloon AND the volume of air outside the balloon to focus upon the real efficacy of using the balloon surface as an analogy for an expanding Universe. Introducing the ant invalidates the analogy completely and all subsequent arguements regarding the state of the ant serve only to obfuscate the intended meaning of the exercise. I think the original arguement was concerned with applying a fixed, scalar reference inside an expanding universe. What changes are observed to the space, matter and the arrangement of matter within that space and the influence that the expansion of the universe was having upon both the nature of the matter AND the measurements of their locations and dimensions relative to each other. I presume that the balloon analogy will not be helpful in resolving that one.

Finally, BenRG brings in a veritable plethora of ideas that both illustrate and clarify the nature of my arguement and afford me the chance to zoom in on the specific point that bothers me and is keeping me from appreciating the work that theoretical physics is doing:

1. The dicotomy between vacuum and matter is not the crux of my questions regarding the nature of space. Any and all descriptions of the interaction between particles (both mass-carrying and force-carrying) may be conceived of as occurring in space without the need to interact with the space in any way. For example; the number of particles, the ratio between their energy levels and their freedom to move within a defined space can be used to calculate their density and even their pressure within a confined space and this can be simply illustrated by analogy without referring to the nature of space - apart from the volume included in the observation. Such a description treats space as a mathematical matrix or yard-stick by which to measure and subsequently observe inherent characteristics of both quantity and quality or behavior. Such observations and calculation do not ascribe any qualitative characteristics to space, only volume is used to provide scale and quantity.
2. BenRG goes on to provide a whole list of potential waves and particles with which to describe phenomena that do not rely upon the presence of space to contribute to their behavior at all. Regardless of our choice to refer to gravity as a wave, a particle, or a wavefunction; any choice is valid and is all that is required to describe the effect it will have upon another particle. The trajectory of a photon is effected by its interaction with a graviton, gravity wave, or the mass of an attendant atomic or sub-atomic particle, which is included in the observation, and can be predicted, tested and described without the use of space as anything other than a location in which to observe and measure the interation. The Standard Model contains sufficient species of particles to carry any and all of the fundamental material and force-characteristics that exist in the Universe bounded by space, without having to assign any of these behaviors to space itself.
3. In essence, we do have to think of space as a "container"; with no unique characteristics nor interactions with matter or force, and useful only as a field of observation, manifestation and quantification of all other species of behavior and existence. Any distortions to this "multidimensional continuum" are by inference alone, they can be explained by interations between particles and/or wavefunctions that describe the inherent characteristics and behaviors of specific modes of energy, manifesting on any level, from the quantum sea of virtual-quarks up to the distribution of galaxies within the Universe.

In conclusion; I see no need to include space as a discreet entity of existence, replete with unique characteristics that are essential to the orderly interaction of all other entities contained in the Standard Model. It appears simply to act as an inert background for manifest existence and only makes an appearance (as the 4 dimensions) when observations and measurements are required. So far, science has failed to convince me (an uneducated but rational humanbeing) that space is a term that describes anything other than the mind's ability to differentiate both scale and distance in reference to an observation of discreet objects.

Respectfully,

GPCViriya (talk) 09:33, 5 March 2010 (UTC)

GPCViriya, you have not sufficiently educated yourself to apply "common sense" arguments to the definition of space. Much of what you say is easily contradicted by referring to any rudimentary cosmology text. For example, you seem to think that space has no attributes; while many would argue that TIME has no attributes (and is, as you said about space, merely a form of measurement), space has attributes, as demonstrated e.g. in the moments between the Big Bang and the completion of the inflationary epoch. Space expanded by something like 10 to the 50th power in a fraction of a second, even though it was a vaccuum at the time. So, at least according to all reputable cosmologists, space indeed has attributes regardless of what it "contains." Seriously: read a book rather than applying "common sense." 63.17.82.123 (talk) 03:25, 6 March 2010 (UTC)

Inverted crater on Mars

I came across this image from the Mars Reconnaissance Orbiter. The image description calls it an inverted crater. What is an inverted crater? Is it just a round-shaped plateau that just happens to look like a crater? According to inverted relief, natural processes on Mars can cause features like river beds that were once depressions to end up above the surface. Is this another example of that? —Preceding unsigned comment added by 72.94.164.21 (talk) 12:33, 4 March 2010 (UTC)

[26] (the official NASA version of the Yahoo story with actual facts and stuff) says that the crater was originally a regular crater that filled up with sediment which compacted and became harder rock than the landscape from which the crater was formed - then erosion eroded away the softer crater walls and the surrounding land to leave the compacted sediment as this "inverted crater". A similar kind of thing happens on earth when a volcano erupts in soft material - then the lava hardens into a really solid rock like basalt - and then the soft ground around it erodes leaving a column of harder basalt. The name for those things escapes me for the moment - but I'm sure someone here will tell us. SteveBaker (talk) 13:33, 4 March 2010 (UTC)

Were you possibly seeking Intrusion or Volcanic plug? -- 124.157.247.225 (talk) 14:53, 4 March 2010 (UTC)

Inverted relief —Preceding unsigned comment added by Telijelly (talk • contribs) 13:52, 4 March 2010 (UTC)

American Cat Scans

Because of the sterotype that americans are fat, there was always this joke going around that amerians would get stuck on cat scan machines. Is it true than quite the contrary, the manufacturers made the machines large to accommodate fat people, but in doing so really thin and small people were unable to use the machines because it was scanning air around them and giving false resulte? —Preceding unsigned comment added by Gordanginton (talk • contribs) 13:26, 4 March 2010 (UTC)

No. First, I doubt the premise of your question. Second, the machines can scan whatever is within their circumference irrespective of whether that happens to be air or flesh. --Tagishsimon (talk) 13:32, 4 March 2010 (UTC)

My wife used to work as a nurse in the radiography department of a large hospital - she said that they had on occasion cat-scanned premature new-born babies - which are about the smallest thing you'd ever consider trying to scan - and that worked perfectly. So no - this is flat out not true. SteveBaker (talk) 13:36, 4 March 2010 (UTC)

does she still work as a nurse, just not in radiography anymore? What department is she working in now? I'm asking because I know someone in a similar situation and wonder what a good switch is from the radiography department. Thanks. —Preceding unsigned comment added by 84.153.250.71 (talk) 14:49, 4 March 2010 (UTC)

I work for a medical device company whose name doubles for a type of screwdriver, and in recent years our marketing materials have been completely written to emphasize the usefulness of our new products in handling "difficult patients" -- this is marketing-speak for fat/overweight/obese however you choose to describe it. Simply put, for something like an ultrasound it just takes more juice to get a good picture when there's more "material" between the sensor and the object you wish to image. 61.189.63.188 (talk) 14:37, 4 March 2010 (UTC)

You work for Flathead?? ike9898 (talk) 14:45, 4 March 2010 (UTC)

Or maybe Stanley ? StuRat (talk) 15:58, 4 March 2010 (UTC)

But there must be limitations on that method. Specifically, doesn't the near flesh get an increased exposure level ? StuRat (talk) 15:55, 4 March 2010 (UTC)

Patient size is a bigger factor for an MRI machine than for a CAT scanner, because the device benefits a lot more from having the sources and sensors close to the subject. MRI machines are notorious for causing claustrophobia. Looie496 (talk) 17:09, 4 March 2010 (UTC)

I was going to ask about that. When I was in grad school, the neuroscience/cognition folks had 3 sizes of MRI machines. I think they had one for humans, one for smaller primates, and one that was smaller yet (dogs? rodents?). I was wondering if the smaller machines worked better on the smaller animals, or if they were just less expensive. -- Coneslayer (talk) 17:13, 4 March 2010 (UTC)

I would think that 1 human sized MRI device would be cheaper then 3, regardless of the size of the others, but if there was a low % of machine downtime, it makes more sense. Googlemeister (talk) 17:30, 4 March 2010 (UTC)

A rodent-scale MRI can get resolution down to a tenth of a millimeter, as I recall, which is 10 times better than you get with an ordinary human MRI, so there are definite advantages to having a separate machine if there is money to buy it. Looie496 (talk) 17:52, 4 March 2010 (UTC)

The logical conclusion, then, is that to do a first rate job of analyzing a foot problem, they should saw it off, run it through a rodent MRI machine, then sew it back on. Among other benefits, this approach would likely reduce the number of people requesting scans for brain tumors. :-) StuRat (talk) 19:01, 4 March 2010 (UTC)

Side issue: Was that a correct use of the word steriotype? Americans have afterall really become on average quite overweight. Dauto (talk) 20:59, 4 March 2010 (UTC)

I've heard stereotype used to mean "any characteristic ascribed to a group of people, whether true or not", so it sounds correct here, to me. StuRat (talk) 22:40, 4 March 2010 (UTC)

The only limits are upper limits. Throughout the 1980s and 90s, most US CAT scan machines had an upper limit capacity of 300 lbs: many radiology depts or imaging centers would refuse to image someone who was heavier. Partly it was fitting in the cylinder and partly it was the warranty limit on the moving parts of the machine. There are no lower limits to size except resolution limits. alteripse (talk) 21:11, 4 March 2010 (UTC)

Compressing Water

Can water be compressed? How much of a space saving will be achieved from compressing water to it's maximum —Preceding unsigned comment added by Harodeuam (talk • contribs) 14:05, 4 March 2010 (UTC)

Yes, but not to any significant degree. See our article on the properties of water for details, but note that at a pressure of 400 atmospheres, water retains over 98% of its original volume. — Lomn 14:13, 4 March 2010 (UTC)

The article mentions oceans at 4 KM. I wonder if there is any info about the compression at around 11 KM, the approximate depth of the Mariana Trench? As I recall from physics class, the reason objects can be crushed at great depths is not so much that the water is "denser", but that there's a column of water several miles high crushing it. But I would think that weight would also impact the density of the water itself - even if only to a small extent? ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:40, 4 March 2010 (UTC)

The article also says that the compressibility decreases as the pressure increases. So if you get 1.8% compression at 4 km depth, the compression at 11 km must be more than that, but less than 5%. --Anonymous, 01:21 UTC, March 5, 2010.

Assuming that doesn't push you past a phase transition to one of water's many allotropes, I think you mean. Not that I've checked whether any of those are much denser, or whether the pressure at 11 km is even close to enough. --Trovatore (talk) 01:26, 5 March 2010 (UTC)

I don't think water has more than one liquid phase; if it did at oceanic pressures I'm sure I would've heard about it somewhere. --Anonymous, 05:15 UTC, March 6, 2010.

I got a related quesiton guys. If you don't store water, but only the hydrogen and the oxygen that you could combust together to produce it, then can you compress THOSE gasses in a way that is equivalent to compressing water? e.g. if you have an x cubic meter room, can you get x + y cubic meters of water to flow out of it, for an appreciable amount of y, not because you had tanks of compressed water in it (which would be very difficult, and the y would be tiny) but because you had tanks of compressed hydrogen and oxygen in it, and combined them to produce your water flow? 84.153.250.71 (talk) 14:44, 4 March 2010 (UTC)

Water has 2 grams of hydrogen per 18 grams of water, which is 18 millilitres, (See molecular formula and atomic weight). By Avogadro's Law, 2 grams of hydrogen under standard pressure and temperature would occupy 22.4 litres, which is 1,244 times the volume of the water it would form when burnt with atmospheric oxygen. The oxygen required would take up 11.2 litres, if it is not available locally. The burning of hydrogen will also produce very high temperature steam, which would then need to be cooled down. So in answer, no, it is not practicable to carry just the hydrogen. CS Miller (talk) 15:15, 4 March 2010 (UTC)

Let's see... at standard temp and pressure, it would take 33.6 liters to store 18 grams of water-equivalent. Assuming that we didn't vary temperature, then, you've got to crunch 33600 milliliters to 18 milliliters to get to water volume equivalence. That would be storing the gases at over 1860 atmospheres. Clearly, this is less practical than just storing water. — Lomn 15:04, 4 March 2010 (UTC)

I'm sorry, I don't get the "upshot". If I have an x cubic meter room underwater (no ambient oxygen source) and I want to store MORE than x cubic liters of water in it, is it better to try to compress water (maybe also cooling it as much as possible short having it freeze and expand) or to try to store it separated, as compressed, cooled gases hydrogen and oxygen? Assume you can just take the heat from combustion and boil the outside water with it... 84.153.250.71 (talk) 15:23, 4 March 2010 (UTC)

p.s. obviously there is no need to store water in a room underwater. I'm just askin'.. 84.153.250.71 (talk) 15:23, 4 March 2010 (UTC)

I doubt it. Reacting 29.5 litres (2kg) of liquid hydrogen with 14 litres (16kg) of liquid oxygen will produce 18 litres of water. I don't have the density of frozen hydrogen or oxygen handy. CS Miller (talk) 16:05, 4 March 2010 (UTC)

There could be a reason. If you want drinking water and you're under the ocean, you'd need to desalinate it and sterilize it before drinking. Whether the apparatus to do this takes up more space than the stored water depends on the duration of the stay as well as the technology used. This is a similar trade-off to space ships either carrying water or recycling water from breath, urine, and poo (when the water comes out brown, it's time to change the filter). StuRat (talk) 15:51, 4 March 2010 (UTC)

(ec)If you read Lomn's response, he is saying that in order to get the hydrogen content of water down to the same volume as the water (before even thinking about the oxygen), you'd need to produce an ungodly amount of pressure. So yes, if you can produce, say 3000-some atmospheres of pressure, you might be able to store it in a smaller volume as independent gasses (though the water itself would likely have compressed a bit more at that point). At a certain point, hydrogen would enter its metallic phase which is basically as a compressible as it gets without triggering fusion. Since you're not going to produce that amount of pressure just to store water, we can safely say you're better off just storing the water. —ShadowRanger ^(talk|stalk) 15:52, 4 March 2010 (UTC)

Oxygen condenses at room temperature under sufficient pressure, doesn't it? It will become essentially incompressible at that point too. I have no idea what that point is, though. --Tango (talk) 04:45, 5 March 2010 (UTC)

No. According to our article, the critical temperature of oxygen is about −118 Celsius. Above that temperature, no amount of pressure can liquefy it. Still, sure, you can compress it to the point where the atoms are more or less touching, and even though it's not a liquid, it will still be almost incompressible at that point. --Trovatore (talk) 06:25, 5 March 2010 (UTC)

If you put oxygen under great pressure, it would behave like a liquid, but you could not get a surface on it. So the resistance to pressure would climb. If you just compress water enough you will get a form of ice, at about 2000 atmospheres. Forming metal by compressing hydrogen or oxygen is much more difficult needing millions of atmospheres of pressure. Ice III has a density of 1.16. So 15% above water. Graeme Bartlett (talk) 09:02, 5 March 2010 (UTC)

What type of medical specialist does this?

This might seem like a request for medical advice, but really it isn't...

The type of medical insurance I have allows me go directly to a specialist without first going to a primary care physician to get a referral. I have an injury which I suspect is something along the lines of a injured upper back muscle (either a small tear or separation from the bone). So, what sort of physician specializes in this sort of problem?

ike9898 (talk) 14:43, 4 March 2010 (UTC)

Orthopedic surgery --Normansmithy (talk) 15:08, 4 March 2010 (UTC)

It's really impossible to decide yourself what the actual cause of a given sensation is. I had a similar shoulder problem, which felt like a joint or tendon malfunction. My doctor diagnosed it, however, as muscular adhesions, and sent me to the physiotherapist. The physio cleared it right up. Figuring out which specialist is appropriate is exactly the job of a primary care physician. -- Finlay McWalter • Talk 21:00, 4 March 2010 (UTC)

No argument, but I'm sure you can see the appeal of possibly reducing the number of doctor appointments you have to go to. Of course, if I initially go to the wrong specialist, that won't save anybody any trouble! ike9898 (talk) 21:46, 4 March 2010 (UTC)

Well, that's the point of visiting a primary care physician. -RobertMel (talk) 19:45, 5 March 2010 (UTC)

Plasma

How is Plasma made? —Preceding unsigned comment added by Harodeuam (talk • contribs) 14:45, 4 March 2010 (UTC)

Are you referring to blood plasma or Plasma (physics), a state of matter comprising partly ionized gas? Blood plasma is made up of lots of different components from different sources: proteins, hormones, glucose, water, etc. Plasma (physics)#Common artificial plasma has information on making the other sort. --Normansmithy (talk) 15:14, 4 March 2010 (UTC)

(EC)Plasma (gas) or Blood plasma (the non-cell part of blood)? (there are other plasmas on the diambiguation page, but these two are the most likely). I suggest looking at those articles. -- Flyguy649 ^talk 15:16, 4 March 2010 (UTC)

Sun size

Daft question i'm sure but...is the sun noticeably 'larger' with the naked eye when you're closer to the equator? The moon obviously varies in how far away it is and it's very noticeable when it's larger, but sitting here in sunny (for today) England fully aware that those near the equator are 'closer' to the sun I was wondering whether that effect is noticeable. I'd recommend some people try but staring at the sun isn't that great for your eyes. ny156uk (talk) 17:22, 4 March 2010 (UTC)

Well, let's think about the scales involved. The sun is somewhere between 90 and 100 million miles away. How much larger do you think it would look if you were 4,000 miles closer (.004%)? This would not be a large enough difference to be noticeable to your average human. Also, the distance from the sun varies by much more then that amount throughout the year because the orbit is not a perfect circle. The moon on the other hand is only about 250,000, so 4,000 miles is around 2%, and might be noticeable. Googlemeister (talk) 17:26, 4 March 2010 (UTC)

(EC) There would be no difference detectable. The earth's mean radius is 6371 km. The mean distance of the earth to the sun is 149.6 million kilometres. Ignoring the 23° tilt of the earth's axis, someone at the pole is one earth radius farther from the sun than someone at the equator. That's 0.004 percent. I doubt there is a noticeable difference in the size of the sun from perihelion to aphelion. -- Flyguy649 ^talk 17:32, 4 March 2010 (UTC)

Also, the width of the Earth may vary by 4000 miles from the poles to the equator, but would vary far less between the equator and England. I'd guess maybe 1500 miles (or 0.0015%), but invite others to do the math. Note that the variation isn't linear, meaning the width of the Earth varies far less from the equator to 45 degrees than from 45 degrees to the poles. StuRat (talk) 17:37, 4 March 2010 (UTC)

File:Lunar libration with phase2.gif Image removed to reduce page load size. Franamax (talk) 21:21, 5 March 2010 (UTC)

Note also that the eccentricity of the Moon's orbit (some 42 000 km variation) dwarfs the equator-to-pole variation and the horizon-to-overhead variation (6 300 km). Between that and the Moon illusion (note that said illusion also holds for the sun, which has no appreciable difference in observable size, so there really is a psychological component), I'm not sure the naked eye would actually observe the difference in an equatorial versus England-based viewing. — Lomn 17:47, 4 March 2010 (UTC)

I posted an gif file that shows the aparent movement of the moon throughout a month (libration) that shows clearly how large is the change in aparent size of the moon due to the eccenticity of its orbit. Dauto (talk) 18:23, 4 March 2010 (UTC)

Interesting animation. It appears to show the Moon rolling slightly upward over the course of the month, which confuses me since one side of the Moon always faces the Earth. Is this just part of a little wobble, or is this an illusion, too ? StuRat (talk) 18:57, 4 March 2010 (UTC)

Libration should have all the details, but it's quite real. The Moon rotates on its axis at an even rate, but it orbits the Earth at a varying rate (due to the orbital eccentricity). The net effect is that the Moon alternately lags and leads, showing nearly 60% of its surface over the course of a sidereal month, even though only the same 50% is visible at any given point in a sidereal month. — Lomn 19:03, 4 March 2010 (UTC)

Is that additional 10% entirely due to libration, or is a small portion also due to having a slightly different view of the Moon from different locations on Earth ? StuRat (talk) 19:26, 4 March 2010 (UTC)

Some very small fraction is gained by moving around the Earth (or by waiting for the Earth to revolve; same effect), but the vast majority is due to the libration. I'd guess it's a difference of three orders of magnitude, though I haven't tried to work the math. — Lomn 21:53, 4 March 2010 (UTC)

Great pace - 3 answers in less than 15 minutes! Yeah figured it wasn't likely but wasn't sure of the numbers. Thanks everyone for their input - just came to me on the way home and figured what the hell i'll ask. ny156uk (talk) 17:44, 4 March 2010 (UTC)

Follow-up question for any who might know: My intuition would be that the size wouldn't change at all due to relative distance (as noted, the delta in the distance is minuscule compared to the total distance), but that it might vary a bit based on changes in the atmospheric lensing. I'm not a physics guy, so I'm probably wrong, but wouldn't the appearance be distorted the further you are from the equator, depending on the season? Perhaps slightly larger in the Northern hemisphere's winter and with a slight disturbance to its shape? Probably not all that observable on a human scale (particularly given the problems with looking directly at the sun), but more measurable than the effect already addressed? Similarly, the shape would change somewhat over the course of the day, since at sunrise and sunset it would be passing through a greater volume of the atmosphere than it does at solar noon? Anyone know if that has an effect greater than, say, a couple millimeters in observed size? —ShadowRanger ^(talk|stalk) 18:14, 4 March 2010 (UTC)

Atmospheric effects ca definately deform the observed shape of the sun. Look at that picture from the green flash article. Dauto (talk) 19:37, 4 March 2010 (UTC)

So presumably for some seasons and latitudes you'll get a visible effect even at midday. After all, above the Arctic circle the sun spends some time effectively permanently rising (or setting, however you want to view it). Still curious if places like London or Manhattan see any such effects (outside of sunrise and sunset), but that at least partially satisfies my curiosity. —ShadowRanger ^(talk|stalk) 19:52, 4 March 2010 (UTC)

I've taken the liberty of thumbnailing the images posted in this thread; the rest of the reference desk should be have to be subjected to such large and distracting images. User:Curious Cactus 20:43, 4 March 2010 (UTC)

Would you believe "should not"? --Anonymous, 01:30 UTC, March 5, 2010.

One further point. Do you notice that the Sun looks smaller in July than in January when it is 3,000,000 miles (5,000,000 km) closer? Then why would you expect to notice when it is 4,000 miles closer due to being seen from a different place on the Earth? --Anonymous, 01:32 UTC, March 3, 2010.

Highway-side notches

There's these weird notches in the pavement that alert a driver to if they are drifting too far to the left or right side of the highway. I want to know how they work, and if we have an article about them. Mac Davis (talk) 17:47, 4 March 2010 (UTC)

Rumble strips. -- Coneslayer (talk) 17:48, 4 March 2010 (UTC)

Thanks. I've noticed that if you drive backwards on them no noise is made, while if you drive forward on them, noise is loud. How could they be designed that way? Mac Davis (talk) 17:57, 4 March 2010 (UTC)

I believe (not 100%) that this is due to the way in which some strips are cut at an angle. If you drive forward, the wheel slowly (relatively speaking) descends the slope, then hits the sharp cut at the far side with the full force of your forward momentum, which jolts both the wheel itself and the attached suspension, creating a louder sound. In reverse, the only impact is the fall off that same ledge onto the slope, so the primary impact is only as strong as the momentum produced by gravity in a fall of an inch or so; your reverse momentum continues with minimal impact.

Of course, when you're going forward, you're usually going faster, so you're going to get more noise in any event, since you rarely go fast in reverse. But for some rumble strips, the slope-and-wall design would account for your experience. —ShadowRanger ^(talk|stalk) 18:04, 4 March 2010 (UTC)

Ah, that makes perfect sense. I should have thought of that. It seems like the notches are not very wide compared to the tire circumference though. I don't know if the tire would really go "up" or "down" a slope. Mac Davis (talk) 18:29, 4 March 2010 (UTC)

Parts of the tire would. They're flexible. So no, usually the tire never reaches the bottom (unless you're really low on air), but it still descends enough to trigger the effect mentioned. —ShadowRanger ^(talk|stalk) 18:30, 4 March 2010 (UTC)

Popcorn

My bag of Boston's Lite Popcorn advertised that it was "whole grain" -- what does that even mean? That they don't remove that brown chaff, because it doesn't seem like anyone removed it (other than corn pops, but that's not popcorn). DRosenbach ^{(Talk | Contribs)} 18:27, 4 March 2010 (UTC)

Whole grain means the bran, endosperm and germ of a plant are found in the product. Mac Davis (talk) 18:31, 4 March 2010 (UTC)

I wasn't asking for the definition of "whole grain" in general, but for its application to corn. DRosenbach ^{(Talk | Contribs)} 18:34, 4 March 2010 (UTC)

It probably means someone in the marketing department had a clever idea. You need the kernel intact in order to trap the moisture to enable popping in the first place. Whole grain is big, so they decided to cash in by mentioning it (despite the fact that it was already the case). At best a "non-whole grain" popcorn might be able to trim a tiny part off the "point" of each kernel (where it connected to the cob) without compromising structural integrity, but I doubt any effort is made to keep or remove it, they just do whatever is most efficient to strip the kernels. —ShadowRanger ^(talk|stalk) 18:34, 4 March 2010 (UTC)

So it's a scam -- just as I thought. Thanx! DRosenbach ^{(Talk | Contribs)} 18:36, 4 March 2010 (UTC)

Well, it's a scam if they are trying to imply that their product is any healthier than other popcorn. On the other hand, it might be useful to remind people that popcorn is a whole grain snack, when comparing with other snacks, like pretzels, where some may be whole grain and others may not be. Of course, the good the extra fiber does you probably pales in comparison with the harm all that salt and grease does. StuRat (talk) 18:49, 4 March 2010 (UTC)

As a good friend of mine says: popcorn is merely a vehicle for butter and salt. Vespine (talk) 23:26, 4 March 2010 (UTC)

You can get hot-air popcorn poppers that add no fat, and you can refrain from adding salt, and then you have a healthy snack that's as tasty as Styrofoam packing peanuts. +Angr 23:49, 4 March 2010 (UTC)

Plus, it's cariostatic (and that was a nice take on it, StuRat...never considered that). DRosenbach ^{(Talk | Contribs)} 04:54, 5 March 2010 (UTC)

How intelligent are beavers

Moved from Talk -- Coneslayer (talk) 18:26, 4 March 2010 (UTC)

How intelligent are beavers? Has anyone done comparative tests? The article on Beaver dams suggests that their dam building is hardwired in but I guess that still makes them the second most intelligent species on the plnet when it comes to building dams, but how do they do in more general things? KTo288 (talk) 18:25, 4 March 2010 (UTC)

I think your premise is based on a skewed view of the definition of intelligence. Bees and other wasps are able to construct virtually perfect three dimensional hexagonal hive structures, but I don't think that makes them smart. Weaver birds construct ridiculously cool nests...but really, all bird nests are cool. It would probably take you a long time to make one, and if likely wouldn't be as neat and sturdy, and you are using two hands with 5 fingers each, while birds generally do it with a beak. Intelligence has nothing to do with this. DRosenbach ^{(Talk | Contribs)} 18:30, 4 March 2010 (UTC)

Intelligence has more to do with pattern recognition and creation based on learned patterns than following instinctive behavior. Mac Davis (talk) 18:32, 4 March 2010 (UTC)

It's not hard to see that a certain amount of very simple but 'logical' thought has to go into the logistics of harvesting trees and building a dam. But,what makes you think that other rodents don't have similar cognitive abilities? Just because squirrels don't have an instinctive ability and need to build damns doesn't mean that they couldn't solve very simple problems. Squirrels often come up with clever ways of defeating anti-squirrel bird feeders. Chipmunks store a surprising amount food for the winter.

A lot of that is trial and error, and not planning things out ahead of time, but it's not like beavers don't make mistakes.

Sometimes beavers fell trees and then later realize they can't get them to the dam site. (I wonder if they're capable of feeling frustration.) Sometimes they start a dam in one place and then abandon the site and build in a slightly different place on the same stream. Sometimes they use a rock or tree as a major structural piece that isn't really tied down well at all.

What makes beavers seem so outstandingly intelligent is their determination and hard work. They make lots of screw-ups, but they keep at it until they get it right. Then you come along in the morning and see their completed dam and imagine that they built it right the first time. APL (talk) 19:37, 4 March 2010 (UTC)

Our article North American Beaver unfortunately does not refer to the intelligence of the species, but does note that in one experiment, researchers placed a cassette tape player, playing the sound of running water, in a field, and the beavers ran over and covered up the tape player with mud and wood to try to make a dam. I believe the editor who introduced this information may have held the view that beavers are idiots. Comet Tuttle (talk) 18:34, 4 March 2010 (UTC)

It is sometimes difficult for us to distinguish between intelligence and instinct. Spider webs also seem amazing, but they are apparently made via a complex set of instinctual actions, as opposed to higher thought and problem solving ability. A more obvious case is birds that "talk". At first it might seem that they are intelligent and holding a conversation, but in short order you realize they just repeat sounds they hear without any knowledge of what they mean. StuRat (talk) 18:43, 4 March 2010 (UTC)

Intelligence is task-specific, so your inquiry cannot really produce any useful results. Suffice to say that beavers can respond to varying conditions fairly well. My dad works as a civil engineer, and there are often issues with beavers causing problems in his municipality. They can make do in a semi-urban landscape, until wildlife control steps in. Vranak (talk) 18:51, 4 March 2010 (UTC)

Thanks for the responses (sorry for asking in the wrong place). From the responses above I guess I'm concentrating too much on the results of what they do rather than how they do it.KTo288 (talk) 21:46, 4 March 2010 (UTC)

PAD vs PADI (peptidylarginine deiminase)

Reading some papers on peptidylarginine deimmanses has gotten me into a fluster! The enzyme citrullinates arginine to citrulline with some interesting consequences, in most the literature the enzymes are abbreviated to PAD, a few refer to them as PADI. However a few papers imply that the PADI is the gene sequence that encodes for PAD.

Some clarity on the matter would be appreciated as I don't want to be refering to genes as if they were proteins...

129.31.206.253 (talk) 19:22, 4 March 2010 (UTC)

I should add the wiki pages aren't helpful, titles refer them as PADIs whereas references refer to them as PAD MedicRoo (talk) 19:26, 4 March 2010 (UTC)

Usually gene names and protein names are the same, with the gene name in italics and the protein Capitalized. However, sometimes there are nomenclature differences between species, e.g. human and rodent. Searching at the Entrez database, shows Padi3 in rats and PADI3 in humans. Pad3/PAD3 are listed as synonyms. I suggest that the PADI vs PAD is probably due to either some minor disagreement amongst researchers or different names in different species. Also, HUGO is the human gene nomenclature database. Similar results can be found there. -- Flyguy649 ^talk 19:38, 4 March 2010 (UTC)

PAD doesn't seem like a good abbrev, to me, since it's also an abbreviation for so many other things, including at least one item in the medical field: Peripheral artery disease. So, if a medical journal has a title "New research on PAD", which do they mean ? StuRat (talk) 19:57, 4 March 2010 (UTC)

If you think that's bad you should check out APC, specifically the four distinct meanings in molecular biology/biochemistry.131.111.185.68 (talk) 23:32, 4 March 2010 (UTC)

StuRat, it is a minor problem since identifying which protein is the subject of the article is usually apparent from other words in the title. If that doesn't make it clear, the abstract will. Clicking on an article found in Pubmed goes to a page with the abstract and a link to the article. Also using an advanced search can help limit results. For example, I used to read papers discussing AP2. The one I was interested in is involved in vesicular trafficking; the other is a transcription factor. I could usually tell by the title which it was. (Both those articles are terrible, by the way). -- Flyguy649 ^talk 16:30, 5 March 2010 (UTC)

But isn't the cost of that extra character worth not having to add more search parameters or read the abstract to tell if you have the right one ? StuRat (talk) 17:57, 5 March 2010 (UTC)

I know what you mean, but it's hard to do in practice. Which one retains the old shortform? I think these problems are less likely to happen with new genes, since every gene now has a unique nomenclature and journals generally require the use of official nomenclature. But genes and proteins that predate genome sequencing are somewhat "grandfathered". Scientists are very resistant to change... traditionally, naming rights go to the earliest publication. But if two labs come up with different names at the roughly the same time, it can become a bit of a pissing contest and it may take years for one form to become dominant. Also, it happens on occasion that scientists don't realize that they are studying the same protein or gene, so there are multiple names for that reason. Or independent nomenclature develops in different species. Sometimes unification works -- e.g. smad proteins is an amalgamation of mad (Drosophila melanogaster) and Sma (Caenorhabitis elegans). Then there are no real rules preventing a gene name from being the same as a short form for a disease or other acronym/short form. Reviewers will likely discourage authors from coining an acronym/shortform if there's an existing well-known use of the same. I guess the short answer is that logic doesn't really prevail in reality! -- Flyguy649 ^talk 21:25, 5 March 2010 (UTC)

I take it that biochemistry lacks something equivalent to the International Astronomical Union, which resolves such naming and classification issues in astronomy. I'm glad astronomers are better organized, or we might still call the planet Uranus by it's original name, George. StuRat (talk) 22:12, 5 March 2010 (UTC)

Unknown beetle that looks like a large ladybug

I found a beetle on my wall today, and am trying to determine what it is. Unfortunately I don't have a picture because, as I was watching it, it attempted to fly away but had a fail and fell down behind something. Now I can't get to it. It looked just like a ladybug, however, except larger. It appeared to be about 1 cm in diameter, shaped like a half-sphere(ie, not a flat insect). It had the second pair of flight wings like ladybugs and many other beetles do. I didn't get a good look at what its head looked like due to the angle it was at and how large the round "shell" wings were, and when I tried to walk closer it fell down, but I believe there may have been long antennae present. Does anybody know of any beetles that resemble this? —Preceding unsigned comment added by 69.243.51.81 (talk) 20:24, 4 March 2010 (UTC)

You'd have to give your physical location to get a useful answer. There are millions of insect species, most of which are confined to extremely limited ranges. —ShadowRanger ^(talk|stalk) 20:37, 4 March 2010 (UTC)

If it looked like a large ladybug, it probably was. It's size just means it's engorged on aphids, a normal part of the ladybugs life cycle at this time of year. User:Curious Cactus 20:40, 4 March 2010 (UTC)

Ladybugs -- Coccinellidae -- are beetles. 1 cm in size is at the upper end of their size range, but there are species that reach 1 cm size. There are also other beetles with approximately "half sphere" body shape; for example, some Chrysomelidae and a number of water beetle species/genera from several families. --Dr Dima (talk) 21:27, 4 March 2010 (UTC)

The OP never denied that ladybugs are beetles. In fact, he confirmed it when he wrote "ladybugs and many other beetles". +Angr 21:32, 4 March 2010 (UTC)

I'm from maryland, so about halfway up the eastern coast of the usa. When I looked up ladybugs, most of the sources I found said that they didn't usually grow past 5mm, so finding one twice that size was what made me think it must be a different species. 69.243.51.81 (talk) 22:31, 4 March 2010 (UTC)

There are very many different species of 'ladybugs' or Coccinellidae beetles (5,000+ worldwide, 450+ in North America), and some are indeed up to 10mm in diameter. It's probably impossible for us to be sure what this one was without a good picture, but Harmonia axyridis (aka the Asian lady beetle, Japanese ladybug or Harlequin Ladybird) seems like a good candidate. 87.81.230.195 (talk) 14:19, 5 March 2010 (UTC)

This is the conclusion my friend and I came to last night. She has those kind in her house, and she routinely sees them as large as I saw the one yesterday, so we think it may have come home in my bag from her house. Thanks for your help. 69.243.51.81 (talk) 16:55, 5 March 2010 (UTC)

Is there any life on the planet Earth?

If we were looking at Earth orbiting a star, is there anything about it which would indicate that it had life? How close would you have to get to detect life? 92.29.76.62 (talk) 20:52, 4 March 2010 (UTC)

You could detect radio signals from earth that would show there was people with that technology. User:Curious Cactus 20:58, 4 March 2010 (UTC)

There's also an argument that the mere presence of abundant atmospheric oxygen would indicate life. The lack of oxygen wouldn't make life impossible, but according to Neil deGrasse Tyson on the Colbert Report a few days ago, oxygen is too prone to reacting with other elements to remain stable without living things to produce it (e.g. cyanobacteria). I doubt this theory is universally accepted, but it's another opinion on the matter.

Your question does require some parameters though. How close are the observers? Martians could see the light from cities on our night side and deduce it was artificial. How technologically advanced are they? We're improving our ability to examine distant stars all the time; as recently as a few years ago we couldn't actually detect planets outside our solar system, now we can detect particularly large ones and even divine some of their properties (mass, distance from their star, certain facts about their atmosphere, etc.). —ShadowRanger ^(talk|stalk) 21:13, 4 March 2010 (UTC)

It's tough to guess how the Martians would think. If the Martians don't know about aerobic life, and instead regard oxygen as a deadly poison, it might not immediately occur to them that high oxygen levels were an indicator for life. Their scientists might spend years debating what sort of unusual geologic process is causing our high oxygen levels. APL (talk) 22:07, 4 March 2010 (UTC)

Martians could also see the greening of each hemisphere's temperate region when it's spring occurs. They might not immediately think of photosynthesis and chlorophyll, but maybe they would. StuRat (talk) 22:32, 4 March 2010 (UTC)

I won't say it is impossible, but I think it is unlikely one could see terrestrial city lights from Mars. The total luminosity of civilization, as viewed from Mars, would be less than 1/1000th of a bright star, and you'd have separate that from reflected sunlight and moonlight. That would be a technically challenging thing to resolve directly. Dragons flight (talk) 06:28, 5 March 2010 (UTC)

1/1000 corresponds to about 7.5 magnitudes. I'm not sure what you mean by "a bright star" exactly, but you must mean at least magnitude 1, I sure, so we're talking no dimmer than magnitude 8.5. That's easily visible with a human eye looking through binoculars. If you look when Mars is at opposition and it's a new moon, the Earth's disc should be completely dark (except near the limbs where some light will be refracted by the atmosphere) and seeing down to mag 8.5 through binoculars shouldn't be at all hard. With a decent telescope, you would have no difficulty at all. --Tango (talk) 06:39, 5 March 2010 (UTC)

In response to Cactus: Intelligent life is different from "life". Radio signals might give the game away, but the question of how to detect low complexity life is quite different. —ShadowRanger ^(talk|stalk) 21:24, 4 March 2010 (UTC)

Of course detection of intelligent life is one indication of "life". My understanding of the state of SETI technology is that it is unlikely that even the most advanced receivers we use today could pick up our own transmissions, with the possible exception of our highest powered military radars, were they being emitted from as far away as the next to nearest star. This was mentioned in a Google Tech Talk on SETI, but I would like to find a better reference and add it to the SETI article. The article currently says: Furthermore, the earth emits considerable radio radiation as a byproduct of communications such as TV and radio, and these radiations would be easy to recognize as artificial due to their repetitive nature and narrow bandwidths. If this is typical, one way of discovering an extraterrestrial civilization might be to detect non-natural radio emissions from a location outside our solar system. I think most people believe it would easy to pick up Earth's television emissions from anywhere within a 73.5 light year radius. 124.157.247.225 (talk) 00:42, 5 March 2010 (UTC)

With regards to people asking about the observers; the OP is specifying if we could detect that life. So, I think we can assume the observes are oxygen-breathing, and at a technology level equal to ours. The question of distance is still unanswered, though. Vimescarrot (talk) 22:29, 4 March 2010 (UTC)

If we were looking at a duplicate Earth, the basic answer is that we could identify intelligent transmitting life from within a radius of a few dozen light years(maybe even a few hundred, depending on the power and directionality of the broadcast) if we were looking in the right direction, but we probably couldn't detect the planet itself if it wasn't in our solar system. If the life isn't using electricity, we'd be blind to anything outside the solar system.

In the next few years (once our interstellar planet detection technology improves a bit so we can detect Earth-sized planets and determine the composition of their atmosphere accurately), we could probably identify the presence of an Earth-sized world with an oxygen atmosphere in a our immediate stellar neighborhood (a few dozen light years in any direction) which would indicate, but not prove the existence of life. —ShadowRanger ^(talk|stalk) 23:00, 4 March 2010 (UTC)

Life was detected on earth with the Galileo and LCROSS probes, but of course these probes were quite close (well within our own solar system). -- Coneslayer (talk) 12:40, 5 March 2010 (UTC)

It is worth mentioning that the most sensitive radio telescope in the world is not sensitive enough to detect a broadcast transmission from the most powerful radio transmitter in the world at the distance of the nearest star (4 light years). Unless a radio signal is being beamed in a very tight beam, it's unlikely to be detectable across interstellar distances assuming the people doing the listening and transmitting are at roughly the same level of technological development as humans. SteveBaker (talk) 20:11, 5 March 2010 (UTC)

Well, but here you're talking about a single transmission, rather than the whole sea of radio emissions from the whole planet, right? I don't know whether he was correct, but I recall a claim by Larry Niven that the Earth emits as much (artificial, I think) radio flux as a small star, and I think we do see small stars in the radio sky. So on the (admittedly shaky) basis that both these statements are correct, we might hope to detect that there is intelligent life via radio observation, even if we can't resolve a particular message. --Trovatore (talk) 20:26, 5 March 2010 (UTC)

See our article Extraterrestrial_life. --Kvasir (talk) 20:36, 5 March 2010 (UTC)

Council house with air conditioning

A council house near me has what looks like air-conditioning. The house is still owned by the council. The climate in the UK does not require air-conditioning. What could explain this? Thanks 92.29.76.62 (talk) 20:56, 4 March 2010 (UTC

Isn't it obvious? The previous residents must have had it installed. Maybe they just had spare money and decided they wanted to try it. Also, the UK does have a climate that would warrant air conditioning in the summer. Especially since global warming it getting worse and worse. User:Curious Cactus 21:02, 4 March 2010 (UTC)

Methinks you do not know what a council house is. It was installed quite recently. 92.29.76.62 (talk) 22:04, 4 March 2010 (UTC)

What kind of air conditioning? Window units or central air? If window units, are they present in every single flat? If they're only present in some, then I'd guess the tenants had them installed at their own expense. I agree it's unlikely a city government would pay for air conditioning for all council house tenants in a climate like the UK's. On the other hand, you only said it looks like air conditioning. Is there anything else it could be? +Angr 22:15, 4 March 2010 (UTC)

A/C doesn't only lower temperatures, it also lowers humidity, and you do sometimes get high humidity there, as on a foggy day. (There are also dehumidifiers, which only lower humidity.) While I doubt if anyone in the UK would die from a lack of A/C, they could certainly be more comfortable at certain times of year with it. Now the question is whether they should pay, at taxpayer expense, to make poor people more comfortable. Some would say yes, others would say no. I would tend to answer differently depending on why they are poor. If they are a drug addict who can't hold a job, then hell no. If they are a paralyzed veteran who was wounded in combat, then yes. StuRat (talk) 22:21, 4 March 2010 (UTC)

Re people dying from lack of A/C: Newspapers do report old people dying of heat in un-air-conditioned homes during hot summers, actually. I don't know if they specified exactly what the cause of death was. Vimescarrot (talk) 22:26, 4 March 2010 (UTC)

Vimescarrot: Heatstroke. Ks0stm ^(T•C•G) 22:37, 4 March 2010 (UTC)

You only get fog on about two or three days in winter - it is clear that you are uniformed about the matter that you are taking about. 92.29.76.62 (talk) 23:21, 4 March 2010 (UTC)

Well, if you can't specify the location any more precisely than "UK", you can't expect us to know the weather very precisely, either, now can you ? StuRat (talk) 03:09, 5 March 2010 (UTC)

The above applies to all of England and Wales, and probably most or all of Scotland. 78.151.93.38 (talk) 14:26, 5 March 2010 (UTC)

So, no place in the UK gets fog more than 3 days a year, and always in winter ? I don't believe that. StuRat (talk) 15:01, 5 March 2010 (UTC)

Great! Now my question is completely ruined and I will never get a sensible answer but several paragraphs of inevitable bickering and worse-than-useless uninformed speculation! 92.29.76.62 (talk) 22:47, 4 March 2010 (UTC)

Welcome to every day on the Wikipedia Reference Desk. Enjoy your stay. User:Curious Cactus 22:52, 4 March 2010 (UTC)

In your question, you basically asked us to speculate on something we have no experience of. We haven't seen the house you're talking about, nor are we in charge of what appliances are installed in it. Unless you provide more information (like answering the questions I asked above, or taking a photograph of the building and posting it here), uninformed speculation is all you can hope for, because quite frankly, it's all your question in its current state can possibly be answered by. +Angr 23:27, 4 March 2010 (UTC)

It is customary and normal etiquette to only answer questions you have knowledge of, rather than just guessing from several thousand miles away. 84.13.22.99 (talk) 00:57, 5 March 2010 (UTC)

Yes but clearly most of the respondents did feel they have sufficient knowledge to be able to offer informed speculation. There's no requirement you actually live in the UK to answer a question concerning the UK. As it stands, the OP still hasn't provided any information to ascertain whether it's possible the tenant installed these airconditioning units which is surely a key point. It's customary and normal etiquette to accept it when people are trying to help regardless of whether you agree with the answer particularly when the question calls for extensive speculation because of the nature of the question and the failure of the questioner to provide any real information even when asked. I would add that I believe VimeCarrot lives somewhere in the UK & Angr lives in Germany, so not 'several thousand miles away'; and I have no idea where User:Curious Cactus lives, do you? Also for all the complaints of pointless bickering, part of the reason this question has gotten offtrack is because of the OP's complaint. Nil Einne (talk) 01:57, 5 March 2010 (UTC)

Are you talking about a window A/C, or a central A/C?. I'm not from the UK, but if it's a window unit, I don't see what's wrong with Cactus's answer. They're cheap and easily installed, someone could have done so on a whim, or because they're fussy or medically sensitive to temperatures or air quality, or whatever.

Central A/C might be more of a mystery, if you're sure that's what it is. In a commercial building I would just assume that there was some technology in the building, like a server-room, that needed A/C, but that doesn't work in a residence. APL (talk) 02:24, 5 March 2010 (UTC)

I was reluctant to say this given the OP's complaints but screw it. It's perhaps worth remembering that many A/Cs can function as heatpumps and would probably be the most efficient form of electrical heating. Here in NZ, they're extensively promoted as such given that many of our houses have extremely shit insulation and many places lack gas heating it probably makes sense. Of course many may use them in the summer as well and this is useful in quite a few parts of the country like Auckland. I appreciate things are different in the UK, but it seems easily possible that the same thing would be an added incentive for some people to have them installed. This ref [27] says they're starting to become standard in new urban developments for example. Nil Einne (talk) 02:41, 5 March 2010 (UTC)

How sure are you that it is a council house and not an ex-council house? The right to buy scheme has resulted in a very large number of council houses now being in private hands. --Tango (talk) 04:49, 5 March 2010 (UTC)

Its absurd that people from the other side of the Atlantic who may never even have set foot in the UK in their lives or even know what a council house is should believe that they can and should answer a question about a UK council house. 89.242.242.77 (talk) 10:04, 5 March 2010 (UTC)

I don't understand why you are so bemused by this. Occupants of council houses have great flexibility in making improvements to them, although the council can insist that it they are kept in good order, and that changes are reversed when the occupants leave. If the current occupants plan on staying for the long-term, they might well decide it is worth installing air conditioning (depending on the system, it may also be possible to take it with them if they move). While most occupants of council houses are on low incomes, it isn't essential; they can stay on if their income increases, and in the few areas where there is a surplus of council housing, they are readily available to anyone. Warofdreams talk 11:50, 5 March 2010 (UTC)

Oh no! Government-owned, subsidized housing is completely unknown out here in the Rest Of The World, How will we ever answer your question about why a residential unit might need a piece of equipment that looks like HVAC unit??!?!?!?

Ok, I think I've figured out the answer you're fishing for, Here you go : "Because the [Political Party] is pandering to the lazy and shiftless poor, and needlessly wasting your tax dollars providing unnecessary luxuries to the [ethnic group] poor!" Does that help? APL (talk) 15:25, 5 March 2010 (UTC)

A tangental query, but what areas have a surplus of council houses please? I thought there were long waiting lists for them. Thanks 78.151.93.38 (talk) 14:07, 5 March 2010 (UTC)

Certain deprived areas in the north and Scotland, which have a lack of demand for housing in general, have surplus council housing. Here, for instance, is a recent document from West Dunbartonshire Council noting that they have around 350 council properties with no demand, while here is something similar from Salford. Of course, it may be that these houses are run down, and with a little investment would be in demand - describing them as "surplus" might well be a way to justify selling them or demolishing them and selling the land, to make the council some quick cash. Warofdreams talk 15:00, 5 March 2010 (UTC)

The what-looks-like air conditioning is a large metal box on the ground within a few inches of the wall of the house containing a large fan, with pipes from it going into the house. It is painted exactly the same colour as the walls of the house, suggesting it was installed at the expense of the local government who own the house. I wonder if it might be required for something like a kidney dialysis machine, but in the past they required an extra room to be built on to the house to contain the machine, and there is no extension on that small house. Perhaps those machines have got smaller in recent years. Council houses are lived in by people who are poor, particularly in that part of the country, and I am sure they would not buy air conditioning on a whim as they are not needed here. The house is still definately owned by the local government. I think its practically impossible that its some sort of cooling equipement for computer servers, as the local council would not give permission, and the people are very likely to be poor, uneducated, and irresponsible. 78.151.93.38 (talk) 14:24, 5 March 2010 (UTC)

Wow, lots of stereotypes there. There are many legitimate reasons why responsible, educated people can find themselves to be poor, such as divorce (and thus needing to support two households on an income that formerly only supported one), illness (making work impossible), etc. And perhaps the people in that house have slightly improved their financial situation, enough to afford A/C, but perhaps not enough to afford better housing. If they needed to get permission from the council to install the A/C, one of the requirements might well have been that they make it blend in as well as possible, including matching the paint color.

Modern dialysis machines are completely self contained and require no external cooling. There could also be a medical necessity for A/C, such as if the person is morbidly obese and thus more prone to heatstroke. Or, they could have severe allergies which prevent them from cooling the house by opening windows. I suggest you contact the council directly, and ask them for the details. StuRat (talk) 15:18, 5 March 2010 (UTC)

Air_source_heat_pumps would be a possibility - these are being promoted as a more efficient replacement for existing electric storage heater or oil heating systems (typically when mains gas is not available). As such the local council could easily have installed the system (grants are also available from central government under energy efficiency programmes). From a UK resident. 94.197.138.254 (talk) 18:28, 5 March 2010 (UTC)

energy from earth's rotation

i'm sure it must be unfeasable, but can't see exactly: why can't we derive power from the angular momentum of the earth? 109.246.247.147 (talk) 20:58, 4 March 2010 (UTC)

See? Do you mean Sea? User:Curious Cactus 20:59, 4 March 2010 (UTC)

corrected to we 109.246.247.147 (talk) 21:17, 4 March 2010 (UTC)

We can derive power from the rotation of the Earth, that's what tidal energy is. Tides are produced by the rotation of the Earth relative to the Moon and, to a lesser extent, the Sun. StuRat (talk) 21:01, 4 March 2010 (UTC)

this is correct, but doesn't quite answer the question i had in mind, which is why is it not possible to transfer momentum from the earth's rotation directly into torque or some other means of driving a earth-based engine? 109.246.247.147 (talk) 21:17, 4 March 2010 (UTC)

Virtually all power generation is based on energy level differentials. In order to derive power *directly* from the angular momentum of the Earth (as opposed to indirectly through the tides), you'd need to find a way to connect it to something not experiencing that momentum. And anything you attached it to would be giving up its kinetic energy to provide the power; deriving energy from the Moon for instance would cause a gradual orbital decay (and/or reduce the rotational speed of the Earth). The tides (and tidal power) are doing basically the same thing, it's just on a scale so low that it has minimal effect on our own rotation and the Moon's orbit. Of course, I'm not a physicist, so I'm sure I made some minor errors in my explanation, but I believe the basic point is sound. —ShadowRanger ^(talk|stalk) 21:20, 4 March 2010 (UTC)

The real reason is angular momentum conservation. BTW the moon's orbit is actually rising, not decaying. Dauto (talk) 21:30, 4 March 2010 (UTC)

I always thought that an orbit can "decay" either upwards, until the object leaves orbit, or downward, until it crashes. StuRat (talk) 22:24, 4 March 2010 (UTC)

Obviously, since the Earth is slowing down. The moon takes up much of that energy (another part is dissipated as heat, and yet another part should actually lift the Earth into a higher orbit around the sun...). --Stephan Schulz (talk) 21:34, 4 March 2010 (UTC)

I would say true, but not obvious.Dauto (talk) 21:38, 4 March 2010 (UTC)

Hmm. If the moon's orbit decays and the Earth slows down, you need a really big energy sink somewhere. --Stephan Schulz (talk) 21:42, 4 March 2010 (UTC)

Heat?Dauto (talk) 21:45, 4 March 2010 (UTC)

Yep. The tidal energy pretty much all turns into heat eventually, either in the water or in the Earth's core, mantle, and crust. StuRat (talk) 22:05, 4 March 2010 (UTC)

It was a rhetoric question but thanks for answering anyways.Dauto (talk) 03:10, 5 March 2010 (UTC)

We had pretty much the same question recently about attaching a gear to the earth Earth GearVespine (talk) 21:43, 4 March 2010 (UTC)

What you want is a 'Gyrogenerator' as seen here in the Museum Of Unworkable Devices. (Second one down on that page.)

Perhaps someone better at crunching the numbers could tell us if this would actually work. (Assuming sufficiently frictionless equipment, of course.) APL (talk) 22:28, 4 March 2010 (UTC)

I think you are confusing energy and momentum. Steve will be along soon to explain it. --Tango (talk) 05:04, 5 March 2010 (UTC)

acidosis

what is the treatment for urinary acidosis other than iv bicarbonate which is just a temporary fix. no other problems can be found to cause this. the person is not diabetic. (this is a hypothetical question.. im not asking for the cause but the treatment. —Preceding unsigned comment added by Thekiller35789 (talk • contribs) 21:36, 4 March 2010 (UTC)

Unfortunately, we cannot recommend treatment options, even in the hypothetical. Please read the Wikipedia:Medical disclaimer. Instead, you should seek, or advise your friend to seek, the advice of a qualified medical professional who can see and treat your friend in person. --Jayron32 22:18, 4 March 2010 (UTC)

contribs) 22:39, 4 March 2010 (UTC)

Also see the reference desk guidelines on the matter, which explains what we do and don't answer here specifically. Acidosis is a particularily good example of why we have these guidelines, because there are different possible causes, and the best treatment is often to eliminate the underlying cause. We cannot hope to diagnose the underlying cause of a specific instance in a specific person, and then proscribe the best form of treatment. If someone you know does have acidosis, they should discuss it with a medical professional who has the access and training to evaluate and treat the condition, rather than asking a random group of people on the internet.Buddy431 (talk) 22:28, 4 March 2010 (UTC)

no one i know has acidosis and neither do i . im just interested in it. it sounds to me like their is no real treatment if no underlying cause can be found ?

This looks like a homework question to me. The answer will be in your text book —Preceding unsigned comment added by 79.68.242.68 (talk) 00:46, 5 March 2010 (UTC)

There is no disease called urinary acidosis. You may be mixing up renal tubular acidosis, which comes in several varieties caused by many different underlying conditions. Treatments also vary according to the underlying condition. alteripse (talk) 02:03, 5 March 2010 (UTC)

im 45 years old and not in school, lol. the acidosis im taking about is when your urine has a low ph. —Preceding unsigned comment added by Thekiller35789 (talk • contribs) 02:39, 5 March 2010 (UTC)

There are uncountable reasons why a person's urine would have an abnormally low pH, and without a proper medical examination to determine the underlying cause, it would be absolutely impossible to recommend a course of treatment for it. That's why we don't answer questions like this; if its idle curiosity Urine#pH contains a very brief discussion of the issue, and articles like Acid-base homeostasis discusses the physiological pH levels in general. You could follow links from there to see what you find. If you have specific concerns about your own urine or the urine of people whom you know, seek a doctor. --Jayron32 06:27, 5 March 2010 (UTC)

zoonoses from dogs

Besides rabies, are there other zoonoses that humans can get from dogs and v v ? Googlemeister (talk) 21:58, 4 March 2010 (UTC)

Kennel cough User:Curious Cactus 22:53, 4 March 2010 (UTC)

The kennel cough article says nothing about transmission between dogs and people. Deor (talk) 23:05, 4 March 2010 (UTC)

Who said that Wikipedia articles are necessarily comprehensive? DRosenbach ^{(Talk | Contribs)} 05:01, 5 March 2010 (UTC)

Wikipedia did! It doesn't say anything about Wikipedia being accurate, though... --Tango (talk) 05:39, 5 March 2010 (UTC)

What about a barking cough? —Preceding unsigned comment added by 79.68.242.68 (talk) 00:48, 5 March 2010 (UTC)

A few come to mind:

• Capnocytophaga canimorsus (one of my favorite bacterial names)
• Pasteurellosis (esp Pasteurella multocida, another great name)
• Ringworm (e.g. Microsporum canis)
• Toxocariasis (esp Toxocara canis as a cause of visceral or ocular larva migrans)
• Cutaneous larva migrans

I'm sure there are others. -- Scray (talk) 06:13, 5 March 2010 (UTC)

There is at least one other, mange. Dismas|^(talk) 16:23, 5 March 2010 (UTC)

Queen bee naughty bits

Resolved

I can't seem to find a good diagram of queen honey bee anatomy to answer this question for myself. Apparently the stinger in most stinging insects is a modified ovipositor. A queen bee has a stinger, and she posits ova (I don't know if she has an ovipositor as such), so how does that work? Thanks. --Sean 22:12, 4 March 2010 (UTC)

It does seem odd and I can't find an explanation. Our article, Bee sting says: "In worker bees, the sting is a modified ovipositor. The queen bee has a smooth sting and can, if need be, sting skin-bearing creatures multiple times, but the queen does not leave the hive under normal conditions." This seems to confirm your statement, but does not really explain it. --Tango (talk) 05:12, 5 March 2010 (UTC)

Why can't it do double duty ? That is, deliver poison, when needed, and eggs when needed. The urethra in mammal males does double duty and the cloaca of many birds, reptiles, etc., does triple duty or more. StuRat (talk) 12:41, 5 March 2010 (UTC)

Perhaps it does, but the sizes seem wrong. A honeybee egg looks like a 1/2 scale grain of rice, and all the stingers I've ever seen are tiny in diameter, like a stout dog hair. I'm going to try a more specialized forum and will report back here. --Sean 13:57, 5 March 2010 (UTC)

I bet a queen bee's stinger is significantly larger, and probably also stretches dramatically when producing young, as a vagina does. StuRat (talk) 14:57, 5 March 2010 (UTC)

Self-answered by following up a ref in Hymenoptera (p. 49 of Introduction to Insect Biology and Diversity): "In the stinging Hymenoptera, the ovipositor no longer functions to deposit eggs; instead, eggs are released from the vaginal opening on the eighth segment." --Sean 21:33, 5 March 2010 (UTC)

Cool. I've put the resolved tag on this Q. StuRat (talk) 13:25, 6 March 2010 (UTC)

March 5

Water for Hydrogen Fuel in Deserts (cont.)

I am continuing from my last question.

Who has proposed using an energy store in deserts? I have recently read a book called Solar Hydrogen Energy: The POWER to save the Earth which proposed that hydrogen be used to transport solar energy from deserts to other places. It also proposed that most production of solar energy be in deserts so they won't take up farmland.

The water in oceans is saltwater. Could we extract the hydrogen used to transport energy from saltwater?

Most combustion of hydrogen as fuel would be in places outside deserts, places all over the world. They would be very far away from deserts. Alot of the combustion of hydrogen would be in transports and not in producing electricity so they wouldn't be transported back to deserts.

An Unknown Person (talk) 04:44, 5 March 2010 (UTC)

There have been lots of proposals to use hydrogen as a storehouse for excess energy production from solar, wind, hydroelectric, etc. It will likely eventually become a common fuel source, however there is an utter lack of hydrogen-fuel infrastructure (basically, no fuel stations exist to sell the stuff; no distribution network exists to get it to the stations, etc.) the way there is with gasoline. So you get a catch-22 with hydrogen as a fuel: No one owns hydrogen-fueled cars because you can't get hydrogen anywhere to fill the tank with, and you can't find hydrogen stations anywhere because there are no customers with hydrogen cars to buy them from. This barrier is what has kept fuel cell vehicles off the road, despite being a feasible means of fueling a car for, oh, 50 years or so. --Jayron32 04:56, 5 March 2010 (UTC)

That doesn't mean it's impossible. I imagine you could start with solar hydrogen production facilities near desert cities, like Las Vegas and Phoenix, and provide refueling stations in those cities and maybe a fleet of rental cars that use hydrogen. You could eventually expand the network with hydrogen pipelines to cities near the desert, like Los Angeles. It might never be feasible to ship hydrogen all the way across the country to places like New York, however, depending on the prices of other fuels. StuRat (talk) 12:32, 5 March 2010 (UTC)

The idea isn't to "ship" hydrogen - it's to use it as a storage medium. The cheapest way to "ship" hydrogen is to burn it to make electricity, send the electricity over wires to the destination and use that electricity to make hydrogen at the other end. Sure, it's inefficient - but it's a LOT easier and safer than building hydrogen pipelines or having trucks or trains carry the stuff. SteveBaker (talk) 20:08, 5 March 2010 (UTC)

You may be right about the advantages of each approach, but the Q was clearly: could "hydrogen be used to transport solar energy from deserts to other places" ? So, that's what I answered. StuRat (talk) 21:24, 5 March 2010 (UTC)

What does the integral of the position function represent?

That is, suppose we have velocity v'. If we integrate (with respect to time), we get position v + c. What do we get if we integrate again?--70.122.117.52 (talk) 05:06, 5 March 2010 (UTC)

The integral of the velocity is displacement, not position. That is, if we integrate a velocity function between any two arbitrary points in time, you get the distance traveled over that time. I'm not sure that integrating the displacement function gets you any meaningful physical quality. Mathematically (especially if you have a complicated velocity function) you could repeatedly integrate any function until you get only a constant left, but that doesn't mean that the operation produces a meaningful physical result. --Jayron32 05:18, 5 March 2010 (UTC)

(ec)The definite integral of velocity is displacement. The OP is talking about the indefinite integral, which would be position if you take the constant as being the starting position. Also, if you repeatedly integrate you don't end up with a constant - that's repeated differentiation. If you repeatedly integrate you end up with some function plus a polynomial (of ever increasing degree). --Tango (talk) 05:32, 5 March 2010 (UTC)

I don't think the integral of position wrt time has any physical significance. It would have units of length times time (eg. metre seconds), which doesn't correspond to anything useful that I can think of (an angular momentum divided by a force, I suppose, but I can't think why you would ever do that). --Tango (talk) 05:32, 5 March 2010 (UTC)

It could have a meaning if there is some other property dependent on the position (∫f(x)⋅dt rather than just ∫x⋅dt). Two ideas:

• A compressed spring. Force is based on displacement, so k⋅distance⋅time is the impulse or momentum-change of the object against which the spring is pushing.
• Some other sort of energy transfer where the transfer/flux falls off linearly over distance. Total transfer is like k⋅(1-distance)⋅time. Hrm, actually all the specific ones I can think of are squared relationships not linear:( Something involving a dashpot/damper or other particle motion through viscous material I guess.

DMacks (talk) 21:39, 5 March 2010 (UTC)

Why would you only end up with a constant through iterated integration? Wouldn't that be what happens through iterated differentiation? —Preceding unsigned comment added by 70.122.117.52 (talk) 05:31, 5 March 2010 (UTC)

Yeah yeah yeah. Stop piling on. --Jayron32 05:34, 5 March 2010 (UTC)

Two people edit conflicting does not a pile make! --Tango (talk) 05:38, 5 March 2010 (UTC)

That depends on the size of the people. I have met people who constitute a pile all by themselves. --Jayron32 06:19, 5 March 2010 (UTC)

Fair point. I don't know about the OP, but I'm pretty skinny - I think you would need at least 3 or 4 of me to constitute a pile. --Tango (talk) 06:24, 5 March 2010 (UTC)

Neither iterated integration, nor iterated differentiation guarantee that you'll end up with a constant. Even with iterated differentiation, that only happens for polynomials. —Preceding unsigned comment added by 157.193.173.205 (talk) 08:22, 5 March 2010 (UTC)

Sun

Could a star like the earths sun just collapse in on itself, like due to chaos theory or something? —Preceding unsigned comment added by Jetterindi (talk • contribs) 09:27, 5 March 2010 (UTC)

No. The sun is not massive enough to become a neutron star or a black hole. In about 5 or 6 billion years it will become a red giant, and then finally a white dwarf surrounded by a planetary nebula. See stellar evolution for more details. Gandalf61 (talk) 09:39, 5 March 2010 (UTC)

I heard this same thing in grade school about thirty years ago. Don't you mean "4,999,999,970 - 5,999,999,970 years"? Kingsfold (talk) 14:19, 5 March 2010 (UTC)

Also, "chaos theory" doesn't mean any crazy thing you can think of might happen. It just means that tiny variations in the beginning of an event can have large and unpredictable effects on the outcome. --Sean 14:19, 5 March 2010 (UTC)

Perhaps the OP is asking whether all the particles in the Sun could move inwards due to random chance (although this could apply to any bunch of matter at >0K). The probability is unfathomably low. --Mark PEA (talk) 11:53, 6 March 2010 (UTC)

Thinking brain?

The idea that our thinking activity is located inside the head seems very natural, but is it something we have learned, or do we know it because we feel the brain thinking? (like e.g. we feel our belly digesting the food). If we have learned it, when did men first have this intuition, and how did they came to it? --pma 10:07, 5 March 2010 (UTC)

comment removed. -- kainaw™ 21:36, 5 March 2010 (UTC)

You obviously saw it in a fictional movie (if your memory is correct), since a head transplant is totally beyond the abilities of science men. 82.113.121.110 (talk) 11:25, 5 March 2010 (UTC)

According to the Head transplant article, the procedure has been Performed with limited success on dogs, monkeys and rats.... Mitch Ames (talk) 11:34, 5 March 2010 (UTC)

even worse, if that was the end of the "experiment", it only proved: a thinking activity was either in the first monkey's head, or in the second monkey's body was thinking, and nowhere in the "scientist". But my question is more on the psychological side: how is that we feel that our thinking activity happens inside our head: is it cultural, that is we learn it when we are kids, or is it physiological, that is, we know what part of our body is thinking much the same way that e.g. we know which part of our body is eating or defecating. --pma 11:45, 5 March 2010 (UTC)

Scientists probably first knew this from people with head injuries, causing brain damage, which led to abnormal thought processes (speech problems, etc.). But people might have thought this intuitively because our perception is associated with our senses, and 4 out of 5 are located on the head alone. This is a rare case where the intuition was right on. One exception seems to be emotion, which instinct told people was in the heart, since it beats faster or slower based on our emotional state. However, emotion, just like logic, actually comes from the brain. StuRat (talk) 12:18, 5 March 2010 (UTC)

History of neuroscience has some useful information. The ancient Egyptians believed intelligence was situated in the heart; Alcmaeon of Croton (c. 500 BC) is claimed to be the first person to suggest the brain was used for thinking. Galen (AD 129 – 199/217) also did work on brain structure. Although little is known about him, Alcmaeon probably used vivisection and dissection to make his discoveries, e.g. cutting the optic nerve of live animals. --Normansmithy (talk) 12:24, 5 March 2010 (UTC)

if thez thought intelligence was situated in the heart, what did they think the material in the skull was for? Also, presumably they knew what some of the other organs did because people injured in those organs all suffered in the same way as a result. Didn't a single person in ancient times suffer traumatic head injury that caused brain damage, so it became obvious to everyone that intelligence and cognitive functions are done there? I seriously can't imagine how they could have thought brain-stuff was for anything else than thinking... what did they think it was? 82.113.121.110 (talk) 13:06, 5 March 2010 (UTC)

The first article linked by Normansmithy above answers your questions directly. Remember that for much of the times under discussion, there were almost no means of communication other than face-to-face, few libraries or other centres of learning existed, and very few people were literate anyway: consequently, most people's opinions could only be based on their own direct experiences. While some did deduce that the brain was the seat of thinking, some thought instead that the brain was merely packing material, and some (following Aristotle's opinion) that its function was to cool the blood which, since the brain does indeed have a very generous blood supply and does indeed create and radiate a significant proportion of the body's heat was, though wrong, not at all unreasonable. 87.81.230.195 (talk) 13:52, 5 March 2010 (UTC)

The best discussion of this issue that I've seen is in The Mind's I, in two essays called "Where am I?" (by Daniel Dennett) and "Where was I?" (by David Hawley Sanford). I think the basic answer is that we feel ourselves to be located in our heads because that's where our eyes are -- we are vision-dominated creatures. By using remote-vision equipment it is possible to create a very strong sense of being located outside your body in various ways. Looie496 (talk) 17:11, 5 March 2010 (UTC)

Thany you all! very interesting information. --pma 08:35, 6 March 2010 (UTC)

Goedel and Wikipedia

Does the Goedel incompleteness theorem imply that insofar as Wikipedia is comprehensive, it cannot be accurate, and insofar as it is accurate, it cannot be comprehensive? 82.113.121.110 (talk) 11:30, 5 March 2010 (UTC)

Gödel's incompleteness theorems deals with questions about the fundamental definitions of maths. It is quite a stretch to apply it to wikipedia, without taking more poetic licence than is normally allocated to pure maths. I think it is nonsense to suppose that wikipedia will ever be complete (even if we knew what that meant in wikipedia terms) not completely accurate. We can duduce all of that without the need to appeal to Gödel. --Tagishsimon (talk) 11:43, 5 March 2010 (UTC)

Wikipedia will not be complete until it contains an article that is about itself. Looie496 (talk) 17:02, 5 March 2010 (UTC)

Please see our article Wikipedia, which is both (IMHO) accurate and comprehensive. So there you go - Goedel disproved, once and for all. Phew! --NorwegianBlue ^talk 19:15, 5 March 2010 (UTC)

Gah, lexical scope ambiguity! I didn't mean an article about Wikipedia, I meant an article with a title something like This article. Looie496 (talk) 19:40, 5 March 2010 (UTC)

Gödel's theorem relates to provability in a formal axiomatic system. It has nothing whatever to tell us about completeness (or truth) in the phenomenal world. --ColinFine (talk) 17:32, 5 March 2010 (UTC)

The problem is the definition of "comprehensive".

1. To truly contain all knowledge (and thereby to be complete) we would have to carefully document (for example) the precise position of every object in the universe and keep that information up to date on a moment-by-moment basis. For truly comprehensive information, we'd require to provide the location of every fundamental particle. The required data storage for such a system would be larger by far than the universe itself - and is therefore quite impossible. This is a kind of "diagonal" argument that Godel and Cantor would have been happy to provide...but it's unrelated to Godel's famous theorem. Hence, true "completeness" is indeed impossible...not just impractical.
2. Fortunately, Wikipedia's own definition of "comprehensive" requires us only to describe things that are "notable" and "referenceable". It probably is theoretically possible to be fully comprehensive within that definition. If every human on earth were to sit down and write articles about every single notable thing that happened to them personally, or which they had written about in a document that Wikipedia would accept as a reference - then they could easily do it within their lifetimes. Most people would be done with it very quickly...and those people would have plenty of time to fill in the notable/referenceable information from past generations...especially since the world population is much larger than it was in previous generations. Doing that would result in a complete, "comprehensive" encyclopedia (within our own definition of that word) in rather a short period of time.

SteveBaker (talk) 19:42, 5 March 2010 (UTC)

First, Wikipedia isn't written in a formal language, so Godel's Incompleteness Theorem doesn't apply. If it were, it would be more like a big list of facts ("1+54 = 55" "7 is prime" "65=65") than a small set of axioms (like the nine Peano axioms, that start "for all x, x=x"). Incompleteness is about the limits of derivable facts. Any list of facts (about an interesting system) is trivially incomplete by virtue of not being infinitely long (but an infinitely long list of facts totally could be complete.) Paul Stansifer 23:08, 5 March 2010 (UTC)

Exactly. For example true arithmetic is complete. True arithmetic satisfies all the stipulations for incompleteness, except the one saying that it can be axiomatized by a computably enumerable set of axioms.

Basically the whole endeavor of trying to apply incompleteness outside of mathematics is fraught with pitfalls. That's not to say it can never be done, but it is to say that some very smart people have wound up making unsound arguments of this sort. Torkel Franzén has a whole book on the subject. --Trovatore (talk) 23:15, 5 March 2010 (UTC)

do we benefit in any way from c?

Is there any benefit for anyone from having a current universal speed limit of c? ie, if the Universe were a democracy, and its lawmaker obeyed the will of the people in it, is there any reason we would do well to have the lawmaker keep c? At least two good reasons for abolishing c from the laws of the universe would be: 1) easier intergalactic space travel, easier communication with probes on mars, etc, 2) smaller ping times to China, and faster processing within a single piece of electronics. In fact, in today's 3 GHz processors, I heard that electrons only have enough time between clock ticks to travel a few centimeters (you can verify this for yourself with a simple Google calculation). Now this means we can't possibly make processors much bigger than that, with logic that has electrons travelling far more than that distance, depending on what path they take. So, this might be a simplification, but abolishing c could also bring better computation power. But as I asked above, my question is now: is there ANY benefit at all from actually having c? 82.113.121.110 (talk) 12:41, 5 March 2010 (UTC)

Your question is nonsense. c is a fundamental constant. Okay, technically there are some limited theoretical circumstances where it bends (shortly after the Big Bang), but we have no control over it. Nature's laws are not up for a vote. —ShadowRanger ^(talk|stalk) 13:13, 5 March 2010 (UTC)

In English, when you say "if the Universe were", the were means that the speaker knows he or she is asking about an imaginary case that is contrary to actual reality. (Otherwise he or she would say "if the Universe turns out to be" or even "if the Universe really is"). So, your point is totally invalid, instead please answer my question: is there any benefit to c, and even though we can't, if we could petition to have this law abolished, would there be any practical benefit to us if we could and we did and it were? —Preceding unsigned comment added by 82.113.106.97 (talk) 13:22, 5 March 2010 (UTC)

There are obvious benefits, as you listed. The question is whether the universe could still exist (in any way still somewhat pleasant to us) if we raised c. After all, it's not a speed limit in isolation of the rest of physics. Fine-tuned universe addresses variations on the question. --Sean 14:32, 5 March 2010 (UTC)

Thanks. Unfortunately your benefit to c in that without it perhaps the Universe "couldn't exist in a way still pleasant to us" is so very broad. Could you, or anyone else, possibly give a more direct, narrow benefit to having c as a speed limit? Does this actually help in a practical, specific (rather than an overarching universal) way? Thanks. 82.113.121.103 (talk) 14:44, 5 March 2010 (UTC)

The slow speed of light has so far prevented the evil Zorn empire from invading from their galaxy and eating our brains. :-) StuRat (talk) 14:42, 5 March 2010 (UTC)

But, seriously, there may well be (or have been) other intelligent species out there which would, at some point, have colonized the Earth if they could only get here, meaning we may never have existed. We don't need to attribute evil motives to them, as they might not have found any intelligent life if they arrived long ago, but maybe they wondered what that slime was in those volcanically heated ponds. StuRat (talk) 14:48, 5 March 2010 (UTC)

This is exactly the type of answer I'm looking for. Do you know of any other answers of this specific nature? 82.113.121.103 (talk) 14:44, 5 March 2010 (UTC)

Perhaps next time, you could specify which type of answer you are looking in front, and save us and yourself some time? :-) DVdm (talk) 14:53, 5 March 2010 (UTC)

um, I didn't have any idea of this answer. I like it because it is specific, and OBVIOUSLY a benefit. I would easily pay any amount of my money not to have my brain eaten by Zorns. Are there any other, specific benefits like this you can list? 82.113.121.103 (talk) 14:58, 5 March 2010 (UTC)

George Gamow wrote a little book "Mr. Tompkins in Wonderlandwherein the Mr. Tompkins dreams about a world where the speed of light was 30 miles per hour. Relativistic effects are seen when someone rides a bicycle. Surely someone has written a similar work where c was orders of magnitude higher. Radio antennas would get bigger, at least for the same frequency. Optics might have to change their size, at least to focus the wavelengths used presently in vision and photography. I wonder if electron orbitals would have to change, along with the the size of atoms and molecules? Edison (talk) 15:03, 5 March 2010 (UTC)

Changing c would change the fine structure constant, and Fine-structure_constant#Anthropic_explanation suggests that that would result in a very different, and probably inhospitable, universe. Also, if you are talking about an infinite c (instead of just a larger c), I'm not sure you would have electromagnetic waves at all anymore. -- Coneslayer (talk) 15:11, 5 March 2010 (UTC)

Okay, the above is a real benefit: smaller radio antennas than if C were larger. Then Cones Layer says the same thing others have been saying, that it's a general requirement for our whole universe. Guys, I got this part. Are there any other specific benefits to the current c, as the bit about smaller antennas is? Thanks. 82.113.121.103 (talk) 15:38, 5 March 2010 (UTC)

I can think of a couple of Japanese cities that would not have suffered as much if the value of c in E=mc² were not so large. TimBuck2 (talk) 17:07, 5 March 2010 (UTC)

Awesome answer. We have all benefited, since if c were larger we may have destroyed all of Japan, or even the entire earth with the first atomic test. Also, if c were a lot smaller, I imagine that we wouldn't be able to generate much electricity through nuclear reactors.24.150.18.30 (talk) 17:44, 6 March 2010 (UTC)

new Best answer (so far) as chosen by OP:

As you increase c, I think it would get harder to implement the Global Positioning System with the same accuracy. Obviously it wouldn't work at all with infinite c. If you must split my name in two, it should be Cone Slayer, not Cones Layer. -- Coneslayer (talk) 15:43, 5 March 2010 (UTC)

Along the same lines, it would be more difficult for us to precisely measure the distance to the moon. —Bkell (talk) 15:54, 5 March 2010 (UTC)

the GPS is the best practical answer anyone here has given so far, and it is spot on, since it relies on specific timing of distances that are travelled at or nearly at c. Therefore, with an infinite or much larger c, this would become difficult. Can anyone come up with other practical aspects of our life that could not work but for c on the scale it currently is? Thank you. 82.113.121.103 (talk) 16:52, 5 March 2010 (UTC)

You're pretty insistent, aren't you? —Bkell (talk) 18:00, 5 March 2010 (UTC)

This is a meaningless question. If 'c' were even slightly different (either more or less) than it actually is, then humans would not exist...but radically different life-forms might. If it were significantly different then probably galaxies and stars wouldn't exist. One of the things you learn after enough years answering questions on the reference desks is that once one utter impossibility has been injected into a question, all else falls to the ground. We can't meaningfully list trivia like GPS being more or less accurate when the elephant in the room is that the existence of all things pretty much depends on 'c' being precisely what it is. GPS could not possibly function in any way whatever if 'c' were more than a percent or two different than it actually is because nobody would have been here to invent it...and in all likelyhood, there wouldn't even be a "here". Sorry - but you don't get to pick between answers you like and answers you don't. You get answers...hopefully true ones. SteveBaker (talk) 19:30, 5 March 2010 (UTC)

I thought he showed outstanding judgment and discernment with his choice of answer. -- Coneslayer (talk) 19:35, 5 March 2010 (UTC)

“

does it really, really look to you like I'm asking "what were to happen if c had never been different from its current value" instead of my actual question about whether there is any benefit to the current state of affairs that would stay our hand if we could choose for c suddenly to change (to increase substantially). Because I tried hard, even introducing the hypothetical idea of a God and of universal suffrage (ahahahaha) into my thought experiment to give a mechanism for the sudden change...

now, having reminded the reader that I am asking about the benefits of c as they pertain to evaluating whether we should request a change in c, the question is: is it meaningless to talk about a sudden change in the value of c, is this simply misunderstanding basic logic. I would agree with you that it is is a misunderstanding of basic logic to ask about a change in conclusions that follow from underlying facts or laws (thus it is meaningless to ask "what if there were only finite primes under ZFC, since the opposite logically follows from ZFC, and so the question would be about finite "primes" under a different, totally unrecognizable system for which the very word 'prime' is arguably not applicable.) Now the question is: is it "meaningless" to even think about the effects of c suddenly changing: is this a meaningless question, as it is meaningless to ask "what if there were suddenly only finite primes starting tomorrow". Well, that would be true if c were a DERIVED value. Unfortunately for your argument, it isn't: it's a basic "magic variable" in the laws of the universe, and NOT a derived or implied figure. Thus our Fundamental Physical Constant article lists c along with vacuum permittivity, Planck's constant, and the gravitational constant G. By the very fact that they are FUNDAMENTAL physical constants, it simply follows that they could be different, or even become different. Who is to say the Universe is not following a program wherein after a certain number of cycles under the starting value, one of the values will suddenly change. The fact that these are FUNDAMENTAL units means that it is not a meaningless thought experiment to ask 'what would happen then.'

Now, having established that it is not out of the question, a priori, that c could suddenly change, I might also ask: is it meaningless and out of the question, a posteriori, that c could suddenly change. What would happen? To read your comment, I should assume every one of my cells would explode, and so would everyone else's, and the Sun would turn from a fusion body to a big dark rock, while our moon became a black hole. Or something equally dire. But why should I assume that? Can anyone here tell me what would suddenly stop working if the speed of light became different suddenly? If c doubled, would my cells explode? Would I stop being able to think?

If someone can explain to me any of the following I will be very happy:

• if c is a fundamental physical constant, then isn't it meaningful to talk of its suddenly changing?
• if it is meaningful to talk of its suddenly changing, then what other physical manifestations (facts that depend on or are derived in part or in whole from c) would change along with it
• would life for me as it exists on Earth instantly disappear if c were to, say, suddenly double at a specific time ie in my personal inertial frame?\

Thanks for any answers to these questions. Note: if you cannot even imagine that the Universe is destined to continue, at some point in the future, from its then current state using the same rules, but with slightly different fundamental constants, then I will respect your viewpoint so long as you admit that if I am able to make a simulation that does behave in this way, then I am, in your world view, more powerful than the Almighty Creator of the Universe, who was not even hypothetically able to do that. I will settle for this admission as well. 82.113.121.94 (talk) 20:28, 5 March 2010 (UTC)

”

If c were infinite, and the universe were also spatially infinite, then the sky would be blindingly bright 24/7, would it not? Vranak (talk) 21:44, 5 March 2010 (UTC)

thank you for the response, can you explain your thinking in more detail, specifically what causes the sky to be brighter than it is now? thank you. 82.113.121.94 (talk) 21:57, 5 March 2010 (UTC)

Olbers' paradox --ColinFine (talk) 00:24, 6 March 2010 (UTC)

If you look up in the sky there is a giant thermonuclear furnace that relies on E=mc2. If you start playing with that c you could either turn off or explode the sun. Even a ~5% change in solar luminosity would change the temperature on Earth about 10 C, so that isn't a balance to be trifled with. Dragons flight (talk) 02:09, 6 March 2010 (UTC)

OK, I'll bite. Your question presumes that a "benefit" must be a "benefit" to "us," i.e., people. We have existed only a fraction of a million years, whereas the universe is 13.8 billion years old. So obviously nothing in the universe exists for "our" benefit. Perhaps you mean "life in general" -- does c benefit life? If light had no speed limit, then light would be infinitely fast. If so, every form of life in the universe would be blind, because all the light in the universe would endlessly travel around the universe; nothing could evolve "eyes," because no organic organ (developing from a primitive predecessor) could adjust to infinite stimulation. So, yes, the speed of light helps "us" because "we" like to be able to see things, which "we" couldn't if "we" were incapable of evolving optical organs. 63.17.82.123 (talk) 04:06, 6 March 2010 (UTC)

Just for kicks, Wikipedia has a page on the variable speed of light (http://en.wikipedia.org/wiki/Variable_speed_of_light) which has some information on cosmologists investigating the possibility of c not always being what it is known as today.24.150.18.30 (talk) 17:52, 6 March 2010 (UTC)

Entropy

Is the Moon a higher or lower entropy environment then the Earth? What caused it? TheFutureAwaits (talk) 12:59, 5 March 2010 (UTC)

Our article on entropy suggests the definition "entropy is as such a function of a system's tendency towards spontaneous change." As such, the Earth is a lower entropy system than the Moon, as it is more prone to spontaneous change, and it is such primarily because it is larger -- large enough to retain an atmosphere and an active volcanic system. — Lomn 14:06, 5 March 2010 (UTC)

I think it's the opposite way : low entropy means highly ordered, for example instead of a moon, a perfect sphere made entirely of a single element and uniformly a single temperature would be highly ordered: you could basically describe it entirely in half a sentence, giving the diameter, the element it is made of, and the temperature (maybe I'm leaving out one or two things). Because you can describe it in very few words, it therefore has a very low entropy. Now the moon has much higher entropy than a perfect sphere made of a single element. You would need far more space to describe it fully. But the earth has a higher entropy still: it is much more complex. So, I would say that the Earth is a higher-entropy environment. To put it another way, as a percentage, you increase entropy far more when you put an American flag into the low-entropy conditions on the moon than when you place on in the high-entropy conditions on an Earthly mountain. Can someone better versed in math and science confirm my interpretation? Thanks. 82.113.121.103 (talk) 14:30, 5 March 2010 (UTC)

That's completely wrong. Entropy is not a measure of how many words it takes to give a macroscopic description of an object. It is measure of how many microscopic states are consistent with the macroscopic description. To labor on your example, if you were to melt the moon, mix if thoroughly and find a way to cool it fast enough to keep the mix uniform the final sphere would have a higher entropy. Read entropy of mixing. Dauto (talk) 15:42, 5 March 2010 (UTC)

I find this extremely hard to believe. You are telling me if we took the universe, melted it all together, and made a black hole out of it, with precisely 0 information in the black hole other than maybe it's total mass (a single real number, in grams) and MAYBE one or two more variables such as it's spin and charge (maybe) then there would be MORE entropy in Universe (even though you can just describe it as "1 black hole, in the "center" (ha ha) of nothing else, having mass x, charge y, and angular momentum z". Even if you give all of these to an obscenely unrealistic level of exactness, you still will use maybe a paragraph of digits. A paragraph, even using the best theoretically possible compression, is not enough to accurately describe (ie represent a compressed version of) even a single book (say, a collection of Shakespeare plays). So it seems to me that a SINGLE book would have more entropy than all of the universe, if you reduced the universe to a black hole. Likewise, it seems to me that a SINGLE city on Earth would have more entropy than the Moon, if the moon were a uniform substance you can perfectly describe in a few words. If I really am wrong, maybe it's because I'm conflating physical entropy with information entropy? For me, the fewer words you can use to give a second God in a different Universe enough information to fully reproduce an exact copy of something, the lower entropy it has. Our God would need to give a LOT of information to a second God in a different Universe to reproduce the Earth, but considerably less if the Earth were a uniform ball that is an exact geometrical sphere, of fixed temperature, density, etc. Don't you think? Can someone confirm whether I'm right, or whether Dauto above is right? Thank you. 82.113.121.103 (talk) 17:13, 5 March 2010 (UTC)

Yes, that's what I'm telling you. In fact for any given mass a black hole will be the state of maximum entropy. See black hole thermodynamics.Dauto (talk) 01:31, 6 March 2010 (UTC)

A small correction: I meant to say that for any given volume a black hole will be the state of maximum entropy. Dauto (talk) 04:20, 6 March 2010 (UTC)

These answers are just leading to more confusion. Dauto, is the Moon higher or lower entropy than the Earth? Why? TheFutureAwaits (talk) 15:56, 5 March 2010 (UTC)

If you take the planet as a whole I would venture that earth's mean specific entropy (entropy per unit volume if you will) will be higher simply because earth's core temperature is higher. Dauto (talk) 16:05, 5 March 2010 (UTC)

My wording may be off, what I'm getting at is which way is the energy exchange moving? So for example in the Sun-Earth system the Sun is increasing in entropy while the Earth is decreasing. How does this work in the Earth-Moon system? TheFutureAwaits (talk) 16:20, 5 March 2010 (UTC)

I doubt there's any meaningful give-and-take between the two. Entropy increases. — Lomn 16:36, 5 March 2010 (UTC)

I don't think the sun's entropy is increasing since the most important factor here is likely the fact that it is losing a massive amount of heat through radiation so its entropy is actually decreasing. The radiation exchange between the earth and the moon is not a very important factor since they are a similar temperatures which means radiation is moving in both directions. Dauto (talk) 16:40, 5 March 2010 (UTC)

Correct me if I'm wrong, but it seems relevant to highlight the increase in entropy of the system, e.g. as the sun radiates energy and mass. The mass that we call the sun one moment becomes a geometrically larger object the next, and the entropy of that system increases (while the entropy of the circumscribed orb we call "the Sun" may decrease). -- Scray (talk) 17:29, 5 March 2010 (UTC)

Probably the most important point is that theoretical thermodynamics shows that entropy per se is not very important -- what matters for understanding interactions is the dependence of entropy on energy, which is measured by a quantity we call the temperature. Looie496 (talk) 16:58, 5 March 2010 (UTC)

panda

Where can you find a giant panda in the United States? —Preceding unsigned comment added by Yelopiclle (talk • contribs) 14:02, 5 March 2010 (UTC)

From the Giant Panda article...

As of 2007, five major North American zoos have Giant Pandas:

• Chapultepec Zoo, Mexico City – home of Xi Hua, born on June 25, 1985, Shuan Shuan, born on June 15, 1987, and Xin Xin, born on July 1, 1990 from Tohui (Tohui born on Chapultepec Zoo on July 21, 1981 and died on November 16, 1993), all females
• San Diego Zoo, San Diego, California – home of Bai Yun (F), Gao Gao (M), Su Lin (F), Zhen Zhen (F), and Yun Zi (M).
• US National Zoo, Washington, D.C. – home of Mei Xiang (F) and Tian Tian (M).
• Zoo Atlanta, Atlanta, Georgia – home of Lun Lun (F), Yang Yang (M) and Xi Lan (M)
• Memphis Zoo, Memphis, Tennessee – home of Ya Ya (F) and Le Le (M)

Googlemeister (talk) 14:18, 5 March 2010 (UTC)

Who's the best when nature calls?

Hi

1.I've often wondered when you have to go, (pee) but sometimes in a situation where you can't (whatever the reason might be). Who's better at holding it, males or females? -However I don't think females can hold it that long.

2. What are the complications of holding a number 2 for too long?

3. I'm sure most guys have had this happen to them somewhere along their lives. However if you've still somehow managed to elude this experience you're in for a treat. I've been hit a couple of times in the groin, but on one or two occations it hurt so bad that I felt I was going to need a new pair of undergarments.

3.1 Is this normal and what are the complications when the injury is serious?

Thanks, NirocFX

41.193.16.234 (talk) 14:05, 5 March 2010 (UTC)

Women can hold for slightly longer in tests, but it's negligible. There are no adverse affects to health of holing a poo in too long, you'll simply lose control of the bowls and crap your pants. And it's very normal to experience massive pain for both men and women when impacted on the genitalia area. They risks include hemorrhaging and sterility. R12IIIeloip (talk) —Preceding undated comment added 14:47, 5 March 2010 (UTC).

I disagree on "holding in poo". The large intestine removes water, and poo held in too long (several days) will thus be dried out and cause constipation. StuRat (talk) 15:37, 5 March 2010 (UTC)

Cecil Adams covered the potential hazards of holding in "Number 1" for too long here. Doesn't mention the other, though. APL (talk) 15:43, 5 March 2010 (UTC)

It's possible to get so constipated it comes out the wrong end. So you might want to hold your tongue too . . . or at least your breath. —Preceding unsigned comment added by 71.108.171.138 (talk) 23:32, 5 March 2010 (UTC)

Was that comment necessary? It is not pertinent to the discussion.--79.68.242.68 (talk) 01:24, 6 March 2010 (UTC)

Microbial locomotion time

If I am trimming the fat from some chicken thighs with a 5" chef's knife, how long could I expect it to take for the potentially harmful bacteria from the blade to make their way to the handle such that my right hand (holding the knife) should be reasonably assumed to be contaminated? I ask because I usually tend to perceive my right hand to be totally clean and use it without much discretion in terms of touching other things in the kitchen while preparing raw meat, such getting a pot from the cabinet, taking things from the fridge, etc. DRosenbach ^{(Talk | Contribs)} 16:40, 5 March 2010 (UTC)

Our Swarming motility article describes this as "rapid (2–10 μm/s) and coordinated translocation of a bacterial population across solid or semi-solid surfaces". If we take the upper end of that range (10 μm/s), then even if the bacteria were to move directly toward your hand, it would take more than 40 minutes for them to move an inch (or a couple of hours for a few inches). Add to that the less-directed nature of bacterial movement, the less-than-ideal culture conditions of a knife surface, and the fact that I assumed the upper end of the range of rates. For most users (perhaps not a trained health professional like yourself), it seems extremely unlikely that this mechanism would account for more contamination of your kitchen than a slip in technique (such as setting the knife down in a "clean" versus "dirty" area). -- Scray (talk) 17:13, 5 March 2010 (UTC)

I dislike that answer. By far the most likely way bacteria would get from something you're cutting onto your hand would be as a fine aerosol of particles sprayed from the object being cut. The mere act of cutting something is going to first stretch - then break and release fibers in the material. As they elastically return to their former shape, they could easily flick microscopic droplets from within the meat or whatever onto your hand. Also air currents and other things could easily be involved. Just measuring the speed a bacterium can move under its' own steam is not going to give you anything but a low-end estimate. I'd guess that the high end is probably 100 mph or something. SteveBaker (talk) 19:18, 5 March 2010 (UTC)

Not sure why you "dislike" that answer enough to make a point of saying so (twice). It's a direct answer to the OP, who asked whether the hand with which he holds the cutting knife is likely to get contaminated by direct spread of the bacteria. The question was not, "how do bacteria spread in the kitchen". I do like your conjectures - they seem plausible (except for the bit about bacterial coming from within intact meat). -- Scray (talk) 20:05, 5 March 2010 (UTC)

120 volt equipment

Hello, Q-what happens to 120 volt 60 hz equipment when it is plugged in to 120 volt 400hz power source? my theory is that it will run for awhile, but eventually it would overheat, example such as an electric motor that's 120 volt hz? —Preceding unsigned comment added by 205.200.77.222 (talk) 16:48, 5 March 2010 (UTC)

It's a difficult question because it depends entirely on the appliance. Somethings will die instantly, others will run perfectly happily, others will be somewhere inbetween. I live in the USA (60Hz, 120v) but have some things I brought with me from the UK (50Hz, 240v) - the cheaper kinds of converters convert to the correct voltage but put out the wrong frequency (ie 60Hz, 240v) and I have several gadgets that don't like that - one overheats, two others just don't work - and that's with just a 10Hz difference! A more expensive converter that I found corrects the frequency too - and that allows those gadgets to work OK. SteveBaker (talk) 19:12, 5 March 2010 (UTC)

In general, using electronics designed for low-frequency power on a high-frequency power input is safer than the other way around -- you don't need to worry about transformer cores saturating and overheating. Electric motors are one of the exceptions: if the input frequency is faster than the motor can spin, the motor won't move at all, and will act as a short circuit. --Carnildo (talk) 02:07, 6 March 2010 (UTC)

Matter

I know matter can be converted to energy, but can it be converted to anything else? Dark matter perhaps?

Its not that matter can be converted into energy, like a magic trick. Its that matter and energy are different expressions of the same fundemental concept. Matter is merely energy which has been confined by the limits of a set of quantum numbers, but fundementally matter is energy and energy is matter. See Mass–energy equivalence for more information. --Jayron32 17:43, 5 March 2010 (UTC)

Ant

Which species of any has a stinger AND bites to inject formic acid into the wounds? —Preceding unsigned comment added by 518c&e (talk • contribs) 17:04, 5 March 2010 (UTC)

Species upper limit?

Have scientists discovered almost all species that exist? —Preceding unsigned comment added by SpiderLighting (talk • contribs) 17:09, 5 March 2010 (UTC)

As surprising as it might seem, only a minority of species have been identified. -RobertMel (talk) 17:15, 5 March 2010 (UTC)

Obviously we have not identified them all, but without knowing how many there are, how do we know we have more then 50% to go? Googlemeister (talk) 17:29, 5 March 2010 (UTC)

And in order to know if we've discovered them all, we'd first have to know how many there are. Which we don't. The species article has some things to say about this. Dismas|^(talk) 17:18, 5 March 2010 (UTC)

Certainly not. Researchers have detected over 700 species of periodontal pathogens in the diseased gum tissue but have characterized and positively identified and marked less than 300 of them -- and that's just bacteria of the gums, let alone of the entire mouth and let alone the entire body and let alone the entire world. But in case you were referring to animal species, the answer would still be no. DRosenbach ^{(Talk | Contribs)} 17:21, 5 March 2010 (UTC)

Likewise, I have heard it speculated that if we counted up all of the discrete animal species we have identified, it would still be less than the number of beetle species yet unidentied. We are no where near ending the catalogueing of species. Furthermore, depending on how you define species, there are some life (bacteria) or pseudolife (virus) forms which speciate at a rate which means that we can get new ones within a human lifespan, meaning that we will never be done. Even if we confine ourselves to macrolife (plants & animals) we aren't even close to being done catalogueing them. --Jayron32 17:41, 5 March 2010 (UTC)

To add that many species will just vanish before we identity them. -RobertMel (talk) 18:04, 5 March 2010 (UTC)

The question of how to estimate the total number of species is interesting. One approach might be sampling. For example, if you take one small island and study it to death to hopefully identify every species, and find that there are 10 times as many as you knew initially, that might be some indication that we know less than 50% of the species worldwide. StuRat (talk) 17:51, 5 March 2010 (UTC)

I suppose you might also plot a graph of the number of newly discovered species per year (adjusted for the number of people hunting them and the amount of effort they put into it) and see if the graph was showing any signs of asymptoting out - which would be a clue that we were close to finding them all. However, (as others have pointed out) there is no way that we're 50% of the way through the process if you include microscopic stuff like bacteria and algea. That 50% number could only possibly be for things the size of insects and above. SteveBaker (talk) 19:06, 5 March 2010 (UTC)

Plus, the definition of the word "species" is far from settled, so you have to argue about that for another few hundred years before you even start counting beetles. --Sean 21:28, 5 March 2010 (UTC)

We've mapped maybe 3% of the floors of the oceans. It is unilkely that this is the coolest 3% out there. There are lots and lots of species in the oceans alone that we have not ever seen. Comet Tuttle (talk) 22:33, 5 March 2010 (UTC)

There are also likely millions of species of microorganisms in soil that we have not yet identified. Do those count? ~AH1^(TCU) 04:01, 6 March 2010 (UTC)

relationship between entropy in physics and entropy in information science?

if you look at my above edit, you will see that I might be very confused indeed. Can someone help explain to me in simple terms what the relationship, if any, is between entropy as understood in physics and entropy as understood in information science? If there is no relationship, why is it the same word? Thank you. —Preceding unsigned comment added by 82.113.121.103 (talk) 17:19, 5 March 2010 (UTC)

We have an article about this. See Entropy in thermodynamics and information theory. In simple terms, entropy is used in both cases to refer to a loss of usability. In thermodynamics, it refers to the loss of Free energy in the universe, or in any closed system. In information theory, it refers to the loss of predictability or understandability in some bit of information. Its sort of like how both biology and chemistry use the word "nucleus" to mean "the bit in the center" (either a cell nucleus or an atomic nucleus.) However, the two entropies are far closer related than that. The mathematics of both is still controlled by the Boltzmann equation, which in information theory takes the slightly different form known as the Hartley function. There are also some gedanken experiments in physics which tie the two fields together nicely. Schroedinger's cat is essentially about information entropy (uncertainty in knowing the state of decay of a single particle is a form of information entropy, as is the fate of our poor cat). The paradox of Maxwell's demon, which conceives of an energy-less way of reducing entropy (and thus SHOULD be a violation of the second law of thermodynamics) can be resolved if we consider information to be negative entropy. I have a nice little "physics for laypeople" primer I should dig up which discusses the connections between information entropy and thermodynamic entropy. --Jayron32 17:37, 5 March 2010 (UTC)

Thank you. Again looking at my above edit, as I referenced at the start of this thread, could you try to understand the way in which I was trying to see black holes, planet-sized highly ordered/uniform/geometrically perfect and easily described objects, and the actual Earth, in terms of "entropy" (which I was using in more the informational sense) and tell me why it doesn't apply (if it doesn't) in a physical sense. ie someone in the linked thread said that I was wrong, and I wonder why (if it's true). Contrary to the implications you make above, physical and information entropy seems to me would have to be opposites in direction/sense in order for me to be wrong above... 82.113.121.103 (talk) 17:49, 5 March 2010 (UTC)

Well, the deal is that entropy is often a slightly misused term in the physical sciences (thermodynamics). Entropy is really just a mathematical concept, after all Ludwig Boltzmann was basically a mathematician. Entropy is just the relationship between the number of possible states of a closed system and the uncertainty of knowing which of those states you are in at any given moment. In thermodynamics, the term is used to basically mean the disorder in a system; it is expressed as negative free energy, or in other terms, entropy is expressed as "the energy needed to return a system to a state of perfect order, where all variables are eliminated and the location of all particles is known with perfect precision". Entropy as a concept is still the mathematical thing, but in thermodynamics we discuss it in terms of the free energy lost in reordering a system. In information theory, the entropy is the same idea; it is based on the number of possible states of a system and the uncertainty of knowing which state the system is in. Information theory actually uses a more pure form of entropy, in that it doesn't use a concept like energy as a surrogate for entropy; it uses a unitless value to express "pure" entropy. But the sign and directionality of the two are the same; the more disordered the system, the higher the value the entropy is. --Jayron32 01:26, 6 March 2010 (UTC)

Jayron, your final conclusion is essentially correct but your argument is stuffed with a potpourri of misconceptions. I won't go into all of them. Let me just point out that entropy and Free energy are not even measured with the same units so your explanation makes no sense. BTW your rant abount physical sciences misusing entropy is also a gem of nonsense. Dauto (talk) 03:20, 6 March 2010 (UTC)

Well, its not that they misuse the term entropy really. Just use it a bit differently than does information theory. And entropy is essentially negative free energy (for any given temperature). At a conceptual level, the two are basically opposite concepts. Entropy is merely disorder, the thermodynamic definition expresses this disorder as a unit of energy per temperature. Free energy is energy availible to do work; we can consider the theoretical "free energy of the universe" to have been at a maximum at the Big Bang, and it has been consitantly decreasing over time. Thus, the for the universe, spontaneousness is represented by a decreasing free energy, or ΔG < 0. The early physical chemists and mathematicians working in this area recognized that this was essentially the functional opposite of entropy; the entropy of the entire universe tends towards a maximum as the free energy tends towards a minimum. When we look at a chemical process, by Helmholtz's and Gibbs's conventions, we tend to take the perspective of "free energy". But removing the math for a second, and looking at the conceptual nature of it. Every process has two contributions to make towards affecting the entropy of the universe. Entropy is temperature dependant (warmer things have faster moving particles, so their position is less certain than cooler things), so any process that tends to heat its surroundings tends to increase the entropy at the universe level. However, most chemical processes also involve a change in organization of the particles, which is a direct effect on the entropy itself. So, if we want to look at a process, there are two things going on: Release or absorbtion of heat, which affects the entropy of the surroundings and reorganization of the substances involved, which affects the entropy of the system. Conceptually, entropy and free energy are basically the same thing in the opposite direction, and in thermodynamics, we tend to express everything in terms of energy, so by convention, the entire thing is expressed in terms of energy values, the classic G = H - TS (Or A = U - TS for the Helmholtzally inclined) which contains the expression of entropy as an energy value (J/K). But this is a convention to give us a number we can find meaning with (usually looking at the "spontanaity" or "extensiveness" of a chemical process) to compare different processes. --Jayron32 04:42, 6 March 2010 (UTC)

You spend a whole paragraph explaining how entropy and free energy are supposed to be the same concept and then write a (correct) equation that shows that they are related but are definitely different concepts and then conclude by saying that the equation is just a convention? Are you a Chemist? Dauto (talk) 15:45, 6 March 2010 (UTC)

Any known planets with satellites with satellites?

Are there any known cases in astronomy of a planet which has a moon orbiting it and that moon has another smaller moon orbiting it?20.137.18.50 (talk) 17:39, 5 March 2010 (UTC)

This question was answered a few years ago - the short answer is "No". The longer answer is that the nature of gravitational and tidal interactions between planet and moon would make a moon-of-a-moon orbitally unstable - so if one ever did somehow come into existence, it would either smack into the planet, the parent moon - or spin off into space within a relatively short period of time. The only exception to that are the various artificial satellites that humans put in orbit around various moons within the solar system - which were there only for short periods of time. SteveBaker (talk) 18:55, 5 March 2010 (UTC)

Thanks, Steve. When Lomm said in that original question "The key consideration (discussed at n-body problem) is that the smallest body must have a mass insignificant with regards to the largest body." with respect to the word "insignificant" are we talking 1/10, 1/100, 1/1000? I followed the link to the n-body problem and didn't see any elaboration of significance of mass difference there, though I have a little more idea of how crazily complex things get with moon-on-moon action. 20.137.18.50 (talk) 19:08, 5 March 2010 (UTC)

A close possibility is the tiny moon Nix and Hydra. They are orbiting a double body system, so in a sense, the satellite is orbiting a pair of satellites where Pluto is orbiting Charon while Charon is simultaneously orbiting Pluto. I suppose someone will come by soon and point out that none of these are technically planets. Googlemeister (talk) 19:16, 5 March 2010 (UTC)

Drat, I was just going to say that. I also wonder if Mercury and maybe Venus lack moons for the same reason, basically that the nearby Sun would knock the moons out of orbit. StuRat (talk) 21:17, 5 March 2010 (UTC)

The Lunar Reconnaissance Orbiter now orbiting the moon is a small artificial 'moon' of the Moon. You may be familiar with the planet. Cuddlyable3 (talk) 03:07, 6 March 2010 (UTC)

The LRO has the mass of a large automobile. Astronomical definitions are notoriously sketchy, but it's doubtful anything the size of a Lincoln Continental would ever be defined as a "moon," artificial or otherwise. 63.17.82.123 (talk) 04:25, 6 March 2010 (UTC)

Well clearly, the sun-earth-moon system has been stable for quite a while, so mass_moon/mass_sun = 3.69e-8 is "insignificant". —Preceding unsigned comment added by 83.134.176.244 (talk) 08:37, 6 March 2010 (UTC)

Doesn't distance play a role ? That might explain why Mercury (and maybe Venus) doesn't have any moons, while Pluto has at least 3. StuRat (talk) 13:22, 6 March 2010 (UTC)

Telescopes

Is there a functional limit on the level of magnification a telescope can achieve? So for example, how big would the lens have to be to read a car's license plate on Earth from Alpha Centauri?

Are there any technologies would could implement that would reduce that size or is it a hard limit? TheFutureAwaits (talk) 18:06, 5 March 2010 (UTC)

Generally speaking, the main purpose of a telescope is not to magnify to a great extent, but to collect as much light as possible, to study faint objects. That said, the angular resolution of a telescope depends primarily on its diameter. The larger the diameter of the telescope, the finer the detail it can resolve. On the surface of the earth, however, atmospheric seeing spoils the resolution of optical telescopes larger than ~10 cm, so you either need advanced technologies like adaptive optics or interferometry, or you need to put the telescope in orbit. -- Coneslayer (talk) 18:13, 5 March 2010 (UTC)

To address your question quantitatively, to read a license plate on Alpha Centauri, you need an angular resolution of roughly θ = (1 cm) / (1 pc) = 3e-19 radians. Using θ = 1.22 λ/D (as explained in angular resolution), and assuming λ = 500 nm (visible light), you need a space telescope with diameter D = 2e12 meters, or 2 billion kilometers, or 13 astronomical units. That's bigger than the orbit of Jupiter. -- Coneslayer (talk) 18:21, 5 March 2010 (UTC)

see http://en.wikipedia.org/wiki/Diffraction_limit —Preceding unsigned comment added by 83.134.176.244 (talk) 18:14, 5 March 2010 (UTC)

(ec) Even ignoring such things as atmospheric distortion and nearby bright things such as the Sun, one important question to consider (I don't know the answer) is how many photons you would need reflected from a license plate in order to be able to read it, and the rate at which these photons would reach Alpha Centauri. Probably you don't even have the remotest chance of being able to read a license plate, because at Alpha Centauri you'd receive one photon reflected from the license plate every 300 years (totally out-of-my-ass guess, but you get the idea). —Bkell (talk) 18:15, 5 March 2010 (UTC)

You could (in theory) solve the issue of the rare appearance of a photon reflected from that license place by integrating the incoming light over a very long period - but now we have a mirror the size of the orbit of Jupiter that's got to stay pointing in the right direction for (perhaps) tens of thousands of years - getting that kind of stability would be really tough - and in any case, that gigantic mirror would have to be moved to track the motion of the license plate relative to the telescope. If it has to point accurately to within 3x10^-19 radians yet move by enough to track the motion of the license plate parent planet rotation - and that planets' orbit around the parent star - and the relative motion of that star with respect to the telescope (not negligable over the amount of time you'd need to be gathering light over)...then the mechanism that moves the mirror would be a horror to construct! This is so far from being a practical possiblity that we're going to have to say that the answer is "No" - you can't do that. SteveBaker (talk) 18:49, 5 March 2010 (UTC)

I wouldn't hold the mirror still, I would just measure its movements and have a computer compensate for them in the final image. --Tango (talk) 19:46, 5 March 2010 (UTC)

Interesting, so then how big of a diameter lens would be required to achieve sufficient angular resolution to read a license plate of a car on Earth assuming there was no atmosphere? TheFutureAwaits (talk) 18:17, 5 March 2010 (UTC)

Hmmm. I read license plates on earth without any lens all the time ;-). --Stephan Schulz (talk) 18:48, 5 March 2010 (UTC)

As Coneslayer already calculated...about the size of the orbit of Jupiter. SteveBaker (talk) 18:49, 5 March 2010 (UTC)

I was still drafting my calculation when TheFutureAwaits asked above. Given the "on Earth" part of this question, I'm not sure if it's meant to be a restatement of the Alpha Centauri question, or a different question. -- Coneslayer (talk) 19:01, 5 March 2010 (UTC)

The mirror does not need to be a disc 13 AU in diameter. You can have a series of smaller telescopes, all coordinated together. This already happens with radio telescopes and I think more rarely with optical telescopes. I cannot recall what this is called - I'm sure there must be an article on it. Edit: see Cambridge Optical Aperture Synthesis Telescope and http://www.mrao.cam.ac.uk/telescopes/coast/handout.html Very Long Baseline Interferometry Perhaps you could just have one telescope at Jupiter and put together what it sees with what it sees six "Jupiter months" later. 89.243.198.135 (talk) 19:13, 5 March 2010 (UTC)

That would be interferometry (or aperture synthesis), which I linked to in my original response. -- Coneslayer (talk) 19:14, 5 March 2010 (UTC)

In regards to Perhaps you could just have one telescope at Jupiter and put together what it sees with what it sees six "Jupiter months" later, no. Interferometric observations must be combined coherently. Without a direct way to measure optical phase, I do not believe there is any way to interferometrically combine optical observations taken at different times. -- Coneslayer (talk) 20:42, 5 March 2010 (UTC)

The Aperture synthesis article says that one telescope with the rotation of the earth is used. What stops a one-year rotation being used instead of a twenty-four hour rotation, at least for radio waves? 89.243.198.135 (talk) 20:53, 5 March 2010 (UTC)

Can you point me to where you're seeing "one telescope"? With a single baseline (two telescopes), you use the rotation of the earth to change the orientation of the baseline relative to the target, which lets you achieve high resolution along different axes at different times. But in any case, that's radio interferometry, not optical interferometry. It's possible to directly record phase of radio signals, which lets you do the interferometry in post-processing. You can't do that in the optical. -- Coneslayer (talk) 20:57, 5 March 2010 (UTC)

The alphacentaurians(?) could at best see only the license plate you had over 4 years ago. Cuddlyable3 (talk) 02:59, 6 March 2010 (UTC)

Even from earth orbit it is very hard to read license plates. I'm wondering why the alphacentaurians stick their license plates on the top of their cars instead of at the ends. Dmcq (talk) 08:44, 6 March 2010 (UTC)

Of course you don't look for license plates in the center of the Earth's disk, but at the very corner, when they are just driving over the horizon. You can even use head and tail lamps for targeting. Duh! --Stephan Schulz (talk) 09:10, 6 March 2010 (UTC)

OTC Cryogenics to treat warts or moles

Are OTC Cryogenics to treat warts or moles? Are they effective? What if a person would apply it on something else? For example, it is for moles and he applies it on a wart or the other way round? Quest09 (talk) 18:38, 5 March 2010 (UTC)

They are to treat warts (and are effective) and their instructions specifically state that they are not to be used on moles. I'll think on the rest of your question, but I think it's bordering on medical advice. -- Flyguy649 ^talk 18:56, 5 March 2010 (UTC)

(edit conflict)I have heard of warts being treated with liquid nitrogen which, amongst other things, stimulates the immune system into responding to the hpv virus that causes the wart. The effectiveness probably depends on the person and type of wart. I'm not sure about moles. — Ƶ§œš¹ _{[aɪm ˈfɹ̠ˤʷɛ̃ɾ̃ˡi]} 18:59, 5 March 2010 (UTC)

I think in general it's a bad idea to think of warts and moles as having anything to do with each other. Warts are viral infections; they need to be gotten rid of, so the virus doesn't spread. Most moles, on the other hand, require no treatment at all; you can just leave them be unless they're bothering you in some way. There are of course exceptions — see malignant melanoma for the worst-case scenario. --Trovatore (talk) 19:01, 5 March 2010 (UTC)

120v v. 240v

How much power could you safely continuously draw through an ordinary domestic 120 volt American electricity socket versus an ordinary domestic British 240 volt (or possibly 220 volts) socket? British electric sockets are installed on a ring main which I think also allows more power to be drawn. Thanks 89.243.198.135 (talk) 20:30, 5 March 2010 (UTC)

I can't speak for UK circuits, but a North American 15 amp circuit is good for about 1800 watts, assuming no other loads. At that rate the circuit breaker may eventually trip if load is continuous. Acroterion _(talk) 20:55, 5 March 2010 (UTC)

UK must be more than that because I had a 2000 watt electric fire plugged into the mains. —Preceding unsigned comment added by Dataport676 (talk • contribs) 21:25, 5 March 2010 (UTC)

The maximum current you can get from a UK socket is 13A - the nominal UK mains voltage is 230V ± 10% (see Mains power around the world). This means that 3kW (13A @ 230.8V) _might_ blow the fuse if the voltage is a bit high (or with a constant-power device and the voltage a bit low). 2kW and 2.5kW devices are common, though. Tevildo (talk) 21:26, 5 March 2010 (UTC)

You can also still get the old BS 546 unfused 15A round-pin plugs (giving you 3.6kW @ 240V), but that's not really an _ordinary_ domestic socket these days. Tevildo (talk) 21:35, 5 March 2010 (UTC)

In Britain the 13A limit mentioned by Tevildo is imposed by a fuse in the standard plug, not the socket. Modern UK houses are wired with a ring main that is capable of delivering 13A to multiple sockets. Therefore by bypassing or up-rating the 13A plug fuse one can draw more current from a British socket, limited by the main fuse. This is not a safe procedure for an amateur but it is possible. Cuddlyable3 (talk) 21:53, 5 March 2010 (UTC)

I would advise very, very strongly _indeed_ against this (unless one wants to burn one's house down). If you need more than 3kW from a socket, replace it with a proper BS 546 15A one. You _can_ get more than 13A out of an ordinary socket by shorting out the fuse. You _can_ get a higher steam pressure in a boiler by welding down the safety valve. The OP, however, included (quite rightly) the word "safely" in the question. This solution does not satisfy that criterion. Tevildo (talk) 22:15, 5 March 2010 (UTC)

As long as you only do it on one device, you should be fine, but if you do it too much you'll trip the circuit. The mains breaker would normally take more effort to trip. --Tango (talk) 22:05, 5 March 2010 (UTC)

Concern for safety is admirable if it is based on facts. BS546 is an outdated British standard for round-pin plugs and sockets that are incompatible with modern 13A BS1363 sockets and lack safety features of BS1363: shuttered socket, finger shrouds, fuse in plug and flat-wiping contacts. If recommending someone install new sockets for high current supply the Europe wide IEC 60309 standard family is preferable because of its modern design. Connectors are colour coded yellow 100-130V, blue 200-250V. Versions for 16 A, 32 A, 63 A and higher are available. Cuddlyable3 (talk) 02:52, 6 March 2010 (UTC)

Similarly in North America, while the standard 120 V socket is intended for circuits fused at 15 A or 20 A, there are higher-current sockets available (yes, for 120 V as well as for 240 V); but in any country such higher-current sockets are meant only for use on a special circuit with heavier wiring than usual. --Anonymous, 05:23 UTC, March 6, 2010.

In UK,ring mains are normally fused at 30 Amps.--79.68.242.68 (talk) 00:17, 6 March 2010 (UTC)

This means that, in the UK, 3kW appliances are common. (The 13a fuse allows up to 3.12 kW at the standard UK voltage of 240v (yes, I know that 220 is quoted, but 240 is standard)). For anything larger than this, it would (in theory) be possible to use multiple plugs and cables, but this would be very dangerous for obvious reasons (live plugs!), so any appliance that draws more than 3 kW must be permanently wired with a high current switch. Instant showers up to 9.8kW are available, fused at 40 amps. Drawing more than 3kW by shorting out the fuse will result in a dangerously hot plug and socket because the connectors are not designed to carry more than 13a. Dbfirs 11:30, 6 March 2010 (UTC)

Genus name

From where did the Genus Zyzzyx derive it's name? Googlemeister (talk) 20:34, 5 March 2010 (UTC)

First paragraph of that article you linked to, emphasis added:

Zyzzyx is a monospecific genus of sand wasp, containing a brightly-colored, medium-sized species, Z. chilensis, named after the sound they make while flying. They were first studied in detail by H. Janvier (a.k.a. Claude-Joseph) in 1928, more than 100 years after they were first described. The unusual name is onomatopoeia for the buzzing sound they make.

Hope that answers your question. —Bkell (talk) 20:36, 5 March 2010 (UTC)

I read that but suspected it was maybe vandalism. Googlemeister (talk) 20:42, 5 March 2010 (UTC)

Ah, okay, that's possible. —Bkell (talk) 20:48, 5 March 2010 (UTC)

This source says Alan Solem named Zyzzyxdonta and Aaadonta "with the idea of being the first and the last entries in any list of endodontoid snails." Not sure if the sand wasp is related. Gobonobo ^{T C} 21:28, 5 March 2010 (UTC)

I've fact-tagged the claims that it's supposed to represent the sound made while flying. There's no citation. Of interest of course is that there is a "Zyzzyx Road" in California, found on Interstate 15 between Los Angeles and Las Vegas. Two films are named after the road, according to our articles; the film Zyzzyx Road is said to have earned a US box office total of US$30, and an international take of over 10,000 times that amount. Comet Tuttle (talk) 23:58, 5 March 2010 (UTC)

The real road is actually Zzyzx Road. —Bkell (talk) 03:57, 6 March 2010 (UTC)

A little confusion concerning E=mc^2

I've been told that the E in E=mc^2 stands for energy in general. But, the equation itself is derived from solving the work integral (with m(v) = γ*m_o), and so I would assume that it is only applicable for kinetic energy. When an object is heated, I can see why its mass would increase: the increased temperature means the atoms are vibrating faster, implying their individual masses are higher (by m(v) = γ*m_o), and thus the object has a higher mass. But for something like binding energy, I'm at a loss as to how the equation E=mc^2 can predict that CO2 would have a lower mass than a carbon atom and two oxygen atoms at the same temperature, or that an object at a higher altitude would have more mass. —Preceding unsigned comment added by 173.179.59.66 (talk) 21:02, 5 March 2010 (UTC)

You might like to ask the maths desk to help with this one

I don't see why. It is clearly a science question. --Tango (talk) 21:27, 5 March 2010 (UTC)

Yes, but it's also maths. I just felt the OP could benefit from a wider insight into his question, for example making a thread at the maths desk directing them here. —Preceding unsigned comment added by Dataport676 (talk • contribs) 21:29, 5 March 2010 (UTC)

It's only maths to the extent that all quantitative science uses maths. We don't notify the maths desk every time a science question is asked on the science desk. --Tango (talk) 21:54, 5 March 2010 (UTC)

E=mc^2 doesn't predict anything about energy, it just tells you the relationship between energy and mass. CO2 will have a lower energy than the atoms separately and E=mc^2 tells us that that means it will have a lower mass. To realise that it has a lower mass you need some results from physical chemistry, not relativity. --Tango (talk) 21:27, 5 March 2010 (UTC)

Right, but the derivation of E=mc^2 seems to be only applicable to kinetic energy. My question is how it can encompass potential energy too. 173.179.59.66 (talk) 21:45, 5 March 2010 (UTC)

There are more complicated derivations which are more general, I think. --Tango (talk) 21:54, 5 March 2010 (UTC)

E=mc^2 is applicable to all energy and mass, not just "kinetic". So potential energy stored between the bonds of a compound makes that compound slightly heavier than the atoms would be seperately. A hydrogen atom is a slightly lower mass than the sum of the mass of a proton and an electron because of the energy released because of the force of attraction between a positive and negative charge, etc. etc. Concepts like "kinetic energy" and "potential energy" aren't relevent to mass-energy equivalence. It's all just energy. So objects moving faster are heavier because of the higher kinetic energy, AND stored-up energy also generates more mass. --Jayron32 01:14, 6 March 2010 (UTC)

As you said, the derivation usually given in introductory books seems to be applicable only to kinetic energy but in fact is is applicable to all forms of energy. Please do the following gedanken experiment: Put some carbon and oxygen inside a box and burn the carbon. During the burning potential energy gets converted into kinetic energy leading to a higher final temperature. Now assume that an observer was passing by with a speed v. From the point of view of that observer the box was moving at constant speed. Since momentum is also conserved, the mass of the box must have remained constant throughout the process. That means that the mass-(kinetic energy) equivalence at the end must have come froma mass-(potential energy) equivalence at the start. Dauto (talk) 01:16, 6 March 2010 (UTC)

Interesting, I never thought of that! Out of curiosity, is this the official derivation, or is there a more "mathematical" method of coming to this conclusion (like through 4-vectors or something of the sort)? —Preceding unsigned comment added by 173.179.59.66 (talk) 07:06, 6 March 2010 (UTC)

Protein architecture, motif, domain, fold, topology.

I'm taking a 4th level biochemistry class titled Protein structure and function and, though I already learned them intro biochem courses, the way the materials are covered is much more detailed. I don't really understand the following: architecture, motif, domain, fold, topology (used in a different sense instead of the more common definition of how the transmembrane protein is embedded). Many of these terms are used interchangeable and I don't have a clear idea of the true definition of each. For example, I saw Alpha/Beta/Alpha domain being also referred to as Alpha/Beta/Alpha architecture. Also, it seems that Greek key motif is also called a Greek key domain, which can also be said to be an architecture. Also, fold and motif seem to be complete synonyms. I'm really confused. Please clarify with clear examples. (PLEASE DON'T JUST REDIRECT ME TO LINKS HAVING GENERAL DEFINITIONS OF EACH, BECAUSE I ALREADY CHECKED MANY OF THEM OUT) —Preceding unsigned comment added by 142.58.129.94 (talk) 21:43, 5 March 2010 (UTC)

Some of these terms are broader or narrower. Architecture is the most broad covering the construction from small to big. The architecture can be made up of those other components. Motif is a pattern that you can see over and over again in different places. domain is a piece of the protein that has a stable shape in itself, so if you chop it off te part will retain this shape. Domain is narrower term or architecture, and may include folds and motifs as components. Fold is pretty clear that it is a bend or change in direction, I would count it as a narrower term of motif, but some think otherwise. The term topology seems to be abused in biochemistry, referring to where parts of the protein chain is, whether embedded in the membrane or poking out. Toploogy in maths will refer more to how it is connected, loops, or multiple elements. Is that 4th year at a uni? I have never studied biochemistry in a class. Graeme Bartlett (talk) 23:31, 5 March 2010 (UTC)

First off, I'm a cell biologist, not a structural biochemist. However, I've seen and used these terms thus:

1. Architecture - the general design of a protein, consisting of perhaps one or more domains or motifs. The architecture of the Src protein consists of an SH2 domain and an SH3 domain
2. motif - a short, often linear, amino acid sequence that can be a target recognition sequence, e.g. LLDLD clathrin interaction motif or PxxP, SH3 binding motif where x = unimportant. These can have different possible amino acids at certain positions, e.g [D/E][G/A]_(0-1)F[G/A][D/E]F binds gamma ear domains of AP-1.
3. domain - usually a larger part of a protein with a specific function and usually a certain fold/folds (i.e. its own 3D structure). e.g. SH3 domains have a consensus sequence and bind certain protein sequences containing a PxxP motif. ENTH domains are large (145 aa) domains at the N-terminus that bind membranes containing specific PIPs. BUT some people use "domain" for motif
4. fold - usually a change in direction in the secondary structure of a protein, but it can mean a fold in the 3D shape of a protein, context dependent
5. topology - the specific 3D shape of a protein either overall or locally, e.g. folds and pockets in a globular region.

Perhaps a structural biologist/protein biochemist can come around and weigh in. -- Flyguy649 ^talk 00:53, 6 March 2010 (UTC)

I dabble in structural biology, though it's not the central focus of my work. I'd like to emphasize that 'fold' in the context of structural biology usually doesn't mean the same thing as it would in a nontechnical context — it's not just a bend or a change in direction. A 'fold' in structural biology generally refers to a particular tertiary structure (at least, an arrangement of secondary structures) which may or may not have a common underlying primary amino acid sequence. For example, the ubiquitin-like proteins (including ubiquitin, NEDD8, and SUMO, among others) all share a 'beta-grasp' fold, in which a beta sheet snuggles up adjacent to (and partially around) an alpha helix. Despite having a very similar tertiary structure, the ubiquitin-like proteins have a relatively limited similarity in sequence. A 'fold' may describe the structure of an entire protein, or a common structure shared by parts of several proteins. (The beta-grasp fold, for instance, shows up in a lot of places.) TenOfAllTrades(talk) 03:34, 6 March 2010 (UTC)

Positive and negative features of CATH and SCOP

They both offer similar services, but how are they different? Can you say which is better? I checked out the tutorial manuals for CATH and SCOP but they aren't very user-friendly. —Preceding unsigned comment added by 142.58.129.94 (talk) 22:22, 5 March 2010 (UTC)

You want the article Systematic Comparison of SCOP and CATH: A new Gold Standard for Protein Structure Analysis, full text here. Cuddlyable3 (talk) 02:15, 6 March 2010 (UTC)

Atoms

Without using a microscope, would it actually be possible to see an atom using just normal magnifying glasses, perhaps using lots of them lined up to increase the zoom? —Preceding unsigned comment added by Firemansam490 (talk • contribs) 22:52, 5 March 2010 (UTC)

No. The most powerful microscopes are scanning electron microscopes. By comparison, optical microscopes have much poorer resolution. Dolphin51 (talk) 23:17, 5 March 2010 (UTC)

Uh, no. We can't even really "see" atoms with a microscope - we need a special kind of microscope (scanning electron microscope) that interprets the image for us, rather than just using lenses to make things look bigger than they are. By the time you lined up enough lenses to hope to see atoms through them, what you saw would just be a big blur anyway - you'd be magnifying the imperfections of the lenses over and over again and the image would be distorted beyond recognition far before you got to the atomic level. - AJ —Preceding unsigned comment added by 71.108.171.138 (talk) 23:22, 5 March 2010 (UTC)

If you line up good magnifying glasses in the right way you will make a microscope, but dont expect much magnification or clear view. Your best chance will be to see gazillions of atoms together making up a visible object. The wavelength of light is about 5000 times bigger than ab atom, so it is like trying to feel a grain of sand with a truck. Graeme Bartlett (talk) 23:37, 5 March 2010 (UTC)

Although it's not optical microscopy, atomic force microscopy lets people image individual molecules and even atoms. Brammers (talk) 00:34, 6 March 2010 (UTC)

Another part of this problem is that it's not at all clear what we mean by a "picture" of an atom. These scanning electron and atomic force microscopes are measuring the field surrounding the atom and turning that into a picture - but that doesn't mean that this is what an atom "looks like" any more than a blind-from-birth person can imagine what someone's face "looks like" by feeling it with their hands. With quantum uncertainty and wave-particle duality effects, it's really meaningless to ask what an atom looks like anyway - even in principle. SteveBaker (talk) 03:22, 6 March 2010 (UTC)

Anthropophobia?

I'm wondering if the following would fall under the diagnosis of anthropophobia or some other term. . . . It's a fear of people, but's it's not "phobic" in the sense of being intense or causing panic symptoms, except occasionally in crowds (at the mall or in line at the grocery store, for example). It's more of an acute discomfort in the presence of human beings in general. It's not sociopathy, because conscience and sympathy aren't lacking. It's not an inability to love or care for others as individuals - quite the contrary. It's just that the presence of even someone very well loved causes a kind of elemental discomfort, and as much as the dear one may be missed in his or her absence, there is a relief and a comfort in solitude that has NEVER been experienced in the presence of any human being under any circumstances. This is so to the point that anticipation of seeing the loved one, even after a long absence or in circumstances such as the loved one's coming home from the hospital which are otherwise incontestably a good thing, prompts mixed feelings. A person in this condition would thrive when left in solitude, but struggle to explain why simply living in close proximity to others induced a sort of emotional paralysis that made it hard to be helpful and productive, since it's hard to be taken seriously when the message they're conveying is "It's not you, really, it's just that you're human," especially when everyone's trying to convince them that what they really need is to get out and socialize more.

Is there a name for this?

It's called Social anxiety disorder.

Wouldn't social anxiety disorder be more about inability to deal with what are conventionally thought of as "social" situations (school, the workplace, gatherings of friends), rather than desiring to hide out from your own mother or spouse?

From our Schizoid personality disorder article: Schizoid personality disorder (SPD) is a personality disorder characterized by a lack of interest in social relationships, a tendency towards a solitary lifestyle, secretiveness, and emotional coldness. Is that close? Googling "schizoid" even yields message boards populated by people who claim they have this order, and discuss their behavior and feelings. (By the way, please type ~~~~ after each post, to sign it, so we can keep track of who is saying what.) Comet Tuttle (talk) 23:53, 5 March 2010 (UTC)

In the movie Men in Black the morgue doctor Laurel Weaver (Linda Fiorentino) has this line "I hate the living." Cuddlyable3 (talk) 01:48, 6 March 2010 (UTC)

Almost all of these 'phobia' words are made up and used indiscriminantly (check out reference 2 in List of phobias for example!). Basically, almost all phobias are basically anxiety disorders - but with different triggers for that anxiety that are probably as varied as the people who suffer from the disorder. SteveBaker (talk) 03:15, 6 March 2010 (UTC)

Changed the earth's axis??

This week's TIME magazine reports that earth's day has been shortened by 1.26 microseconds as one result of Chile's earthquake, and the reason is because the earth's axis got shifted about 3 inches.

Could someone expand on this, provide a little more detail on how one caused the other? The only explanation I can imagine -- that the diameter of the earth is now slightly smaller due to subduction -- doesn't make ANY sense at all! DaHorsesMouth (talk) 23:16, 5 March 2010 (UTC)

You are basically correct, the Earth's moment of inertia was reduced by about 15 parts per trillion as dense rock subducted deeper into the earth and displaced less dense rock (and/or changed the shape of the sea floor). Along 700 km of the fault, the Earth jumped up to 10 m, which is enough to have a tiny but perceptible effect of the Earth as a whole. Dragons flight (talk) 01:38, 6 March 2010 (UTC)

And, when you move the mass inward on a spinning body, it spins faster, resulting in a shorter day, due to conservation of (angular) momentum. StuRat (talk) 02:51, 6 March 2010 (UTC)

But how would that shift the earth's axis? 95.112.175.41 (talk) 09:02, 6 March 2010 (UTC)

The stuff about the Earth's "axis" is a bit of a red herring, and not surprisingly most of the newspapers have got the story confused. The BBC's version is particularly bad, showing a completely irrelevant diagram of the precession of the axis. If Richard Gross of NASA JPL is to believed, this is what happened: the Earth's mass distribution shifted, as Dragons flight correctly said. This shift had two effects. 1: the Earth's "figure axis" (the one that passes through its centre of mass) shifted by a few metres; 2: the rotation sped up due to the reduction in the moment of inertia. Effect 1 is not related to the length of the day, although I guess it might cause a few places on Earth to shift time zones by a few nanoseconds. Effect 2 is what (is predicted to have) shortened the day by a microsecond. --Heron (talk) 10:28, 6 March 2010 (UTC)

Sorry, can't find anything about shifted axis in Richard Gross article. Wouldn't that be even violating momentum conservation? 95.112.175.41 (talk) 11:51, 6 March 2010 (UTC)

I can't remember exactly where I got that claim from, but there are plenty of other examples on the web. For example, this similar article by National Geographic attributes the figure axis shift to Gross. --Heron (talk) 15:36, 6 March 2010 (UTC)

voltage

what is the maximum voltage that can be artificially generated within the limitations of current technology? —Preceding unsigned comment added by 129.67.118.243 (talk) 23:59, 5 March 2010 (UTC)

I aksed my science teacher this once, they said that voltage is infinite it's current that matters. You could have a balizzion volts with no current and it wouldn't kill you, or you could have 1 volt with a balizzion currents and it'd fry you like a deep fried mars bar. —Preceding unsigned comment added by Zonic4 (talk • contribs) 00:03, 6 March 2010 (UTC)

Some modern Van de Graaff generators can create a potential difference of up to 5 megavolts (that's 5 000 000 volts), Our high voltage article says that lightning can have a potential difference of up to 1 gigavolt (1 000 000 000 volts) (though I don't see a reference, and that isn't artificial). Buddy431 (talk) 01:03, 6 March 2010 (UTC)

According to our Van de Graaff generator article, the record is 25.5 million volts at Oak Ridge, although that particular statistic is uncited. The limiting factor is the breakdown voltage of the insulation between the collector dome and the rest of the structure - the Oak Ridge machine (and others like it) use sulphur hexafluoride. Tevildo (talk) 01:14, 6 March 2010 (UTC)

(edit conflict)Voltage merely means that you have two points in space with electrons at different levels of potential energy. When the potential energy difference becomes great enough, the electrons are "forced" to move from the higher energy state to the lower one (i.e. generate a current). Once the current starts to flow, the voltage will lower slightly, until the current reaches a steady state, and the system reaches equilibrium according to Ohm's Law. However, back to the main question, there is no theoretical upper limit to voltage, this article at google news: [28] shows that 5,000,000 volts was attained in 1923. We can only assume the number to be orders of magnitude higher today. I can't find anything else using google, but if you play around with search terms, you may be able to find something. --Jayron32 01:09, 6 March 2010 (UTC)

I would say tens of megavolts for a short period: but thats just my gut feeling. No evidence Im afraid.--79.68.242.68 (talk) 01:12, 6 March 2010 (UTC)

Plasma acceleration has shown a transient electron acceleration equivalent to 40 billion volts, but the process is not really the same as the way we usually think about voltage, and field only exists for about a nanosecond. Dragons flight (talk) 01:25, 6 March 2010 (UTC)

An Electron microscope built[29] at Osaka University uses a 3 000 000V supply from a Cockcroft–Walton generator. Cuddlyable3 (talk) 02:01, 6 March 2010 (UTC)

I was hoping to find answers in Orders of magnitude (voltage) - but the article didn't exist, so I had to write it - which means that there is nothing there that hasn't already been said. SteveBaker (talk) 03:08, 6 March 2010 (UTC)

March 6

Genetics and cousins

If a man marries a woman then his brother marries the woman's sister and both couples have children, how many genes do the children share with their cousins compared to regular cousins? --124.254.77.148 (talk) 02:21, 6 March 2010 (UTC)

They would be double cousins. That article says "Genetically, they are as related as half-siblings, sharing 25% of their DNA (a coefficient of relationship of 1/4)." --Tango (talk) 02:26, 6 March 2010 (UTC)

But, of course, that's just an average. They could actually share anywhere from 0% of their chromosomes (unless they are both male, in which case the cousins must share a Y chromosome) to 100%, which would also require that their two sets of parents were 100% genetically identical. Of course, the extremes are extremely unlikely, but exactly 25% is unlikely, too. (Or should I say impossible, since 46 chromosomes aren't divisible by 4.) StuRat (talk) 02:45, 6 March 2010 (UTC)

It is more complicated than that since chromosomes don't stay intact - genes can move around when the chromosomes are splitting. See Chromosomal crossover. --Tango (talk) 02:55, 6 March 2010 (UTC)

Please note that there is absolutely nothing tabboo about this arrangement (two siblings marrying, respectively, two other siblings), it is not incestuous or dangerous or anything like that. 82.113.121.104 (talk) 10:07, 6 March 2010 (UTC)

Except, apparently, in West Virginia and North Carolina. --80.177.170.180 (talk) 11:15, 6 March 2010 (UTC)

:Each of my grandfathers had some double cousins, and I've turned out orl write normal. --80.177.170.180 (talk) 11:14, 6 March 2010 (UTC)

red shift versus blue shift

Redshift and blue shift

In considering red shift and blue shift would not it make more accurate or reliable not to think in terms of eyes or ears as being stationary and the object moving as denoted by oneway pointers but rather as both observer and object being subject to motion using dual pointers such as <<<<<<>>>>>> and >>>>>>><<<<<<<? 71.100.11.118 (talk) 03:03, 6 March 2010 (UTC)

If you are talking about redshift of light in vacuum than it makes no difference. Dauto (talk) 03:12, 6 March 2010 (UTC)

I'm including a moving siren in air that passes me while riding down the highway. 71.100.11.118 (talk) 03:16, 6 March 2010 (UTC)

Than yes, you are right. It makes some difference whether the source, the observer, or both are moving.Dauto (talk) 04:05, 6 March 2010 (UTC)

For sound...yes...because the medium that it's passing through is "stationary" so the symmetry between moving observer and moving source is broken. But the redshift in light doesn't do that because in a vacuum, there is no stationary 'reference'. Light is weird. SteveBaker (talk) 06:53, 6 March 2010 (UTC)

red shift and blue shift for objects in the Universe

Is the average amount of red shift the same in opposite directions when observing from Earth or slightly less or more in any particular direction? 71.100.11.118 (talk) 03:14, 6 March 2010 (UTC)

I'm not really sure what you mean by the average amount of redshift - what are you averaging over? The Cosmic Microwave Background radiation is redshifted more in one direction than the other (see Cosmic Microwave Background#CMBR dipole anisotropy), if that helps. --Tango (talk) 04:42, 6 March 2010 (UTC)

For instance perhaps in a binary star system where the red shift will vary in degree and possible to the extent of going int the blue (assuming the system were close enough, the orbital speed high enough, etc.) 71.100.11.118 (talk) 05:24, 6 March 2010 (UTC)

Freeze data outside U.S.

Is it possible to find information on the dates for the first freeze in the fall and the last freeze in the spring for places outside the U.S.A.? All my effort so far has yielded no fruit - all the information I can find (online at least) seems to be limited to the U.S.A. which seems very strange - don't gardeners in, say, Romania or Korea need to know just as well?

69.140.13.88 (talk) 03:45, 6 March 2010 (UTC)Nightvid

Even the data available for the USA might not be reliable during the oncoming of global warming. For instance I've lived in Florida since 1951 and I've never experienced more than two weeks of temperatures below 40 Deg F. This year we still have temperature down to freezing in early March. 71.100.11.118 (talk) 04:03, 6 March 2010 (UTC)

Here's a very specific example for a small city in Germany [30]. Aaadddaaammm (talk) 11:09, 6 March 2010 (UTC)

Northern England (UK): earliest autumn freeze in the last fifty years was September 1st when a whole row of my still-flowering hydrangeas turned a surreal black! Night-frosts occur well into June (summer here), but I don't have exact dates. Parts of Scotland will fare worse. This site [31] might be of interest. Dbfirs 12:15, 6 March 2010 (UTC)

Static electricity damage

I recently discharged static electricity accidentally on a stereo. It's not a very high tech one but ever since i was unable to power it on. When plugged in, the 12:00 keeps flashing, that's about it. Any way an electronic device like this can be repaired? What component is likely damaged? Maybe there is something I can replace inside? Thx.

Our article has only one line about this topic. --Kvasir (talk) 05:02, 6 March 2010 (UTC)

You'd have to take it to an electronic repair shop. Once static electricity "sparks" or discharges, it becomes an electric current (and thus no longer static). Sending a pulse of unregulated electrical current through a device with hundreds of tiny electronic devices and hundreds of more little connections and wires means the current could have literally "fried" anything. There are hundreds of options as to what you fried, and there is no way, without carefully analyzing the device, to identify which little connection or tidbit or doofulator you fried. It would only take one. So, you'll need to find someone that speciallizes in repairing these devices, though theres a better than 50/50 chance that the stereo is unfixable even by an expert. --Jayron32 05:07, 6 March 2010 (UTC)

Beyond the 50/50 chance of being unrepairable, there is a much higher chance that a brand new one will be cheaper than the cost of repairing the old one. Electronics keep getting better and cheaper. Many electronic devices are now considered nearly disposable, like cell phones and mp3 players. -- kainaw™ 05:12, 6 March 2010 (UTC)

Static damage is very insidious. It can cause chips to fail intermittently - or not fail at all for weeks after the event and then suddenly die. You could easily pay a stack of money to repair it - only to find that it fails again soon after. Also, diagnosing these faults is pretty tough so unless they do a "repair-by-replacement", swapping out all of the electronics in the unit - the cost of figuring out which chips died would be very hard. Electrostatic discharge may be of some interest. The most likely components to fail are the chips - knobs, buttons, wires, connectors, circuit board tracks, discrete transistors, resistors, capacitors, diodes and coils are unlikely to fail - and the fact that the display is flashing says it's not the display or the power supply. So probably there are a couple of chips in there - and one or more of them is 'fried'. Replacing the chips one at a time would be the most likely approach to succeed - but honestly, I agree with the others...much as it pains me to say so: forget it - buy a new one - contribute more nasty electronics waste to your local landfill. :-( SteveBaker (talk) 06:43, 6 March 2010 (UTC)

Most electrical devices have gold film to conduct the static to the sites of the device and way from the chips. This sometimes results in a slight shock when touching them, but protects the internal operations. —Preceding unsigned comment added by VCRVLC1010 (talk • contribs) 17:22, 6 March 2010 (UTC)

Relativity

To my understanding, Einstein said that, in order for the laws of physics to remain consistent with the principle of relativity and the universality of the speed of light, a moving object must undergo length contraction, time dialation, and mass increase. If we were to view an object as consisting of a collection of charges, would it be possible to also derive the same results via electromagnetic theory? I saw the article on electromagnetic mass, which said that the velocity dependancy of the electron's mass was predicted before relativity using E&M, so I was wondering if the same was possible with time dialation and such, or whether they are considered to be beyond the perview of E&M theory. —Preceding unsigned comment added by 173.179.59.66 (talk) 07:15, 6 March 2010 (UTC)

None of the effects that you claim (length contraction, time dialation, and mass increase) actually occur in the reference frame of the moving object. An observer on the moving object would find everything normal, but would observe that the rest of the universe appeared distorted. (Sorry I don't know enough about E&M to answer your question, but Steve or some other expert will give a better answer.) Dbfirs 12:28, 6 March 2010 (UTC)

Let me try. You could solve the Maxwell equations for an electromagnetically bound system, say a low-mass negative charge orbiting a stationary high-mass positive charge (note: such orbits are not stable but that isn't important here). Then, you solve the Maxwell equations again for the same system, only now it's moving at a constant speed in a constant direction. Obviously, you don't get to use the Lorentz transformation to simplify your problem (that would be assuming your answer), no, you must solve it in the original frame of reference by using, among other things, a current rather than a stationary central charge. Since you solved it in the original frame of reference, you will find that your solution is length-contracted relative to your original non-moving solution. —Preceding unsigned comment added by 83.134.176.244 (talk) 12:52, 6 March 2010 (UTC)

Yes, and even Einstein himself derives "time dilation" from an argument based on a "light clock" (i.e. light bouncing back and forth between mirrors) which can be seen as a system comprised of an EM field obeying Maxwell's Equations with reflecting boundary conditions. If you want, those boundary conditions can be derived from microscopic physics based upon the Lorentz force of the light's EM fields on the charges in the conductor/mirror, which in turn reradiate. All of this could have been done with pre-1905 electromagnetic theory which is nonetheless fully relativistic! 69.140.13.88 (talk) 16:09, 6 March 2010 (UTC)Nightvid

Cool, thanks! —Preceding unsigned comment added by 173.179.59.66 (talk) 16:45, 6 March 2010 (UTC)

Circular DNA

In published sequences of circular DNA molecules (I'm thinking chloroplast DNA specifically), how do they determine the numbering system? Ie. who/what decides which nucleotide is the first? Aaadddaaammm (talk) 11:07, 6 March 2010 (UTC)

it would make sense for the first one to be the first one that was created while the strand of DNA was being copied. 82.113.121.104 (talk) 13:18, 6 March 2010 (UTC)

That would make sense, but I seriously doubt that's the case - often which nucleotide is copied first is not known exactly. I imagine the choice is somewhat arbitrary, and made by the team who initially sequenced the DNA. They may choose a prominent feature (like the start of a gene), or they may not. For example, the start position of the E. coli genome is about a million base pairs away from the origin of replication. In the footnote to the E. coli sequencing paper (Blattner et al. Science, 277(5331) page 1453) they note that the zero position was originally defined as the first residue of the thrA gene, which had been previously used in mapping the chromosome, but that they decided to move the start position for the complete genome 189 nucleotides upstream, to include the thrA promoter with the gene. I do know that once a choice has been made for one piece of DNA (say the pBR322 plasmid), derivatives/related DNA (like the pET vector series) tend to use the same numbering system. I'll also note that even for linear DNA like nuclear chromosomes, the numbering system is arbitrary, as telomeres, centromeres, and other unsequenced/unsequencable repeat systems make a global numbering system unwieldy/impractical. -- 174.21.226.184 (talk) 16:51, 6 March 2010 (UTC)

This is more of a question than an answer: Doesn't the loop have to detach into a more conventional linear sequence in order to reproduce? With 'normal' DNA, the two sides of the helix are unzipped and replicated - that doesn't seem reasonable for circular DNA (unless it doesn't do the "double helix" thing) because you'd end up with an inextricable tangle. If my guess is right then the circle has to break somewhere when being copied - and maybe there is a special place where that has to happen? If THAT is true - then that would be the logical place to start the numbering. But I have no clue whether any of that is true - I'd like to hear the answer. SteveBaker (talk) 17:35, 6 March 2010 (UTC)

For general unknotting of DNA, there are a whole group of specialized proteins: the topoisomerases. (See also this link.) TenOfAllTrades(talk) 17:49, 6 March 2010 (UTC)

Surviving in a Vacuum

Last nights episode of QI said that a person can survive for a short time in a vacuum, basically until they can't hold their breath anymore and die from suffocation. Is this actually true? I would have thought they'd be exploded by the lack of pressure and boil alive because the boiling point in a vacuum is much lower. Also, Stephen Fry said someone in a vacuum would simultaneously defecate, urinate and vomit because of the pressure. Is that also true?

This has been discussed many times before (well not sure about the defecate, urinate and vomit bit), you may want to search to read the previous answers. But basically Space exposure covers it well. In particular note that it's estimate people could survive about 90 seconds but holding your breath is a bad idea Nil Einne (talk) 11:14, 6 March 2010 (UTC)

And the pee, poo and puke is from Decompression sickness, linked to in the Space exposure article. Nanonic (talk) 12:44, 6 March 2010 (UTC)

Space question

I'm trying to understand the concept of space but I just doesn't make sense to me. Space has nothing in it right? Except for planets and moons and bits of rock floating about. So why aren't those things sucked towards each other to fill the emptiness? How can there be an area with absolutely nothing in it? On earth we have air to fill the gap, but in outter space there's nothing? Please help me to understand. How can something exist when it's nothing? —Preceding unsigned comment added by W359 (talk • contribs) 16:50, 6 March 2010 (UTC)

Space (even the space between galaxies) does have very small amounts of 'stuff' in it - odd stray molecules of gas. The "air" that we breathe is also "mostly vacuum" - there are big gaps between the molecules. It's only when you get a liquid or a solid that the molecules come close to touching - and even then, the individual atoms have nuclei that are an unimaginably tiny fraction of the size of the atom - so even something as solid as a rock or a table is almost all empty space. The difference between what we call "air" and what we call "vacuum" is just a matter of degree. The reason the air stays in our atmosphere is the same as the reason we stay stuck on the ground - gravity. The reason that gravity doesn't suck all of the planets into the sun is because the are orbiting and as they whirl round in their orbits, the centrifugal force of that motion exactly counters the gravity of the sun. The sun and other stars don't get sucked into the giant black hole in the middle of our galaxy is because they too are orbiting. Galaxies sometimes do collide with each other and get pulled apart by each other's gravity. That's believed to be happening to our galaxy right now. But what (in general) stops galaxies from just being smooshed together by their own gravity is because space itself is stretching as the universe expands after the Big Bang. That expansion is enough to overcome the mutual gravitation between distant galaxies simply because gravity gets so weak over such enormous distances. SteveBaker (talk) 17:26, 6 March 2010 (UTC)

Orders of magnitude (voltage) help.

Last night, I started the Orders of magnitude (voltage) article (I love the 'orders of magnitude' series of articles - they are really handy for answering Ref.Desk questions!). I've found good examples for every order of magnitude from 10⁰V (a AA battery) up to 10⁸V (typical lightning bolts) which is probably about the largest voltage out there. So we're good for the positive orders of magnitude. But what I'm missing is good examples (preferably common/not-obscure) of voltages of 0.1V downwards (preferably with something I can reference). Help! SteveBaker (talk) 17:49, 6 March 2010 (UTC)