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January 5

sky colors over a blue stars

This question tends to trick everyone, everyone is having a tough time deciding if the star is blue and the planet have earthlike atmosphere, would the sky still be blue or it would have color of something else. If star is any other color, then the sky is blue that easy if it have earthlike atmosphere , if no atmosphere the sky is black.--69.226.34.161 (talk) 01:36, 5 January 2010 (UTC)

Is there a specific question? -- kainaw™ 01:39, 5 January 2010 (UTC)

I meant if earth was orbiting a blue star what color will the sky be, because the blue star has blue light, people would wonder if a blue star will emit blue light, the sky wouldn't be black at this case.--69.226.34.161 (talk) 02:55, 5 January 2010 (UTC)

Of course a blue star emits blue light, that's what makes it blue... Despite your rather confused description of the problem, I think I understand. You want to know what colour the sky would be for an Earth-like atmosphere of a planet orbiting a blue star. That's simple enough - it would be blue. The colour of the sky is due to Rayleigh scattering. The particles in the air scatter blue light more than they scatter light of longer wavelengths, and it is that scattered light that we see when we look up but not towards the sun. The light from a blue star will be scattered the same way. Blue stars still emit over a wide range of wavelengths, just with the peak nearer the blue end of the spectrum (actually, probably in the UV part of spectrum). More interesting would be the sky of a planet orbiting a red star - red stars emit very little blue light (not none, though), so the sky would look very dark (but still blue - or, at least, bluer than the star itself looks). This is all assuming human eyes - life that evolved on those planets would have eyes that see in the range where their star emits most of its light (just as we do), so people on the blue star planet would actually see the sky as UV (which they would be able to see) and people on the red star planet would probably see the sky as green (since they wouldn't be able to see blue). --Tango (talk) 03:23, 5 January 2010 (UTC)

It's a bad idea to speculate on how life around some other star might evolve. Sure, humans have evolved vision that's a good 'fit' for the brightest part of our sun's spectrum - but plenty of other animals see in the infra-red (Owls and some kinds of snake, for example) while others have evolved to see in the ultra-violet (bees, for example). So we can't conclude that evolution would necessarily drive all life to seeing colors that match that of the peak output of their local star. We truly don't know how (and cannot meaningfully speculate) how these hypothetical aliens might see their sky. SteveBaker (talk) 17:40, 5 January 2010 (UTC)

"It's a bad idea to speculate on how life around some other star might evolve." No, it is not. Speculating about what could be is the driving force of science. Of course, it has to be accompanied with calculation, experimentation and observation (the later two being very difficult is this special case). What has gotten into you? I know you from previous years of posting and providing knowledge and help here but lately you tend to answer questions by something equivalent to "It is not, so it cannot be. Full stop." I am worried. 93.132.156.195 (talk) 17:25, 6 January 2010 (UTC)

As I understand it, animals that see into UV or IR only see very near UV or IR. An O-type main sequence star (which is described as being blue) has a minimum surface temperature of 30000K, which corresponds to a peak wavelength of 100nm - that is Extreme ultraviolet, a long way from the near UV that bees can see. (The upper end of O-type is 52000K, or 56nm peak.) I think it is fair to say that all animals on Earth (with the exception of blind cave dwellers, I suppose) are adapted to where the Sun emits most of its light, the differences are fairly minor. --Tango (talk) 21:09, 5 January 2010 (UTC)

You should also keep in mind that the atmosphere matters. An atmosphere with a large oxygen content, like ours, is fully opaque below about 280 nm. It doesn't matter what is emitted if the life forms can never see it. Dragons flight (talk) 21:23, 5 January 2010 (UTC)

That is an excellent point. --Tango (talk) 21:54, 5 January 2010 (UTC)

Bees see UV out to about 300nm - so that makes perfect sense. They can see all the way to the top of the UV spectrum - as transmitted by the atmosphere. SteveBaker (talk) 00:02, 6 January 2010 (UTC)

Anyone want to add information on bee eyesight to bee? Seems like a useful detail. Dragons flight (talk) 21:28, 5 January 2010 (UTC)

I did a little googling, but didn't find any useful reliable sources, just a few unreliable sources that were enough for me to make an educated guess from. I wouldn't be happy including educated guesses in an article. If someone can find better sources, it would be good to include it in the article. We also have Colour_vision#In_other_animals, that could do with expanding (there is more than one paragraph to say on the subject - it could probably have its own article). --Tango (talk) 21:54, 5 January 2010 (UTC)

It's described in detail in Chapter 8 of Richard Dawkins' Climbing Mount Improbable - which includes a pair of photos of a flower, one in normal light and the other in UV - showing how the flower has an ultraviolet 'target' on it, showing the bees the way to the nectar at the center. His bibliography references: "The Honey Bee" by Gould J.L and Gould C.G, "Bumblebee Economics" by Heinrich, B. Online, you can view Dawkin's lecture to the Royal Institution (you don't get much more prestigious than that!) entitled "The UltraViolet Garden" here. "The Natural History of Pollination" by Michael Proctor, Peter Yeo has a diagram at the top of page 131 that shows that Bee vision uses three color receptors - one in yellow, one in blue and the other in UV - going out to 300nm wavelengths. Also "The Pollination of Flowers" by Proctor and Yeo, Collins, 1973, ISBN 0 00 213178 1 has a section about this - and there is more online stuff here Hopefully, that's more than enough reference for such a well-known fact about bee vision. SteveBaker (talk) 23:51, 5 January 2010 (UTC)

UV stands for ultraviolet, looking at this article it actually means black light. Spectrum drawn shown UV end as more or less black.--69.226.34.161 (talk) 04:10, 5 January 2010 (UTC)

"Black light" is actually a casual non-scientific term used in limited applications for what is more formally called Ultraviolet, not the opposite as you seem to suggest. It's shown as black because we humans cannot see it directly (just as we cannot see Infrared) but many other creatures (for example, Bees) can, so it is not "black" to them and they presumably perceive the coloration of the sky and the rest of the world differently to us. 87.81.230.195 (talk) 15:11, 5 January 2010 (UTC)

It's interesting to note that humans actually can see UV, if you remove the cornea, which normally blocks it for health and safety reasons. We can also see x-rays, to a degree, fuzzily, dangerously, in a dark room, but I believe that's through a different mechanism to our normal vision. --Sean 16:31, 5 January 2010 (UTC)

Of course UV isn't a single color/frequency. It's a band of frequencies. People who have had their cornea(s) removed can see a little way into the 'near' ultraviolet - but not as far as (for example) bees can. My mother had hers removed during cataract surgery - it's important to note that you really don't see any 'new colors' - you still only have red, green and blue sensors - so UV light looks just like a very normal blueish violet color. What is interesting is that flowers that are pollinated by bees have evolved to present certain patterns in UV light that are not there in normal human vision. My mother (being an avid gardener) has noticed odd (and very feint) blue/violet stripes and splotches on some kinds of flowers that she couldn't see before - so there is not doubt that she's seeing some of what a bee sees. SteveBaker (talk) 17:40, 5 January 2010 (UTC)

Since this thread has wandered into speculation about superhuman forms of vision we might revisit the archaic idea that the eye sees by projecting instead of receiving rays. That means that what a colour would look like is defined before one sees it. (This is not nonsense, it is how ray tracing in CGI works. Superman's X-ray spectacles must work this way too.) X-rays have a 4-decade frequency range (3E16 to 3E19 Hz) but AFAIK all medical X-ray photographs are monochrome. What wondrous false-colour images they might show through us! I have read that a British local council once decreed a prohibition against use of X-ray spectacles. Cuddlyable3 (talk) 00:02, 6 January 2010 (UTC)

Would we get interesting false colour images? That would require different types of body tissue/bones to have different variations in their opacity to different frequencies of x-ray. Is that the case? --Tango (talk) 00:20, 6 January 2010 (UTC)

I suspect that is the case. Different target (anode) materials have different characteristic spectral emission and absorption frequencies. Charles Barkla received the 1917 Nobel Prize in Physics for his discovery of the characteristic X-ray line spectra of different elements. Furthermore any diffraction effects, such as from crystal structures, are wavelength dependent. One certainly gets differing X-ray medical images with and without injected radiopaque contrast masterial. Cuddlyable3 (talk) 01:55, 6 January 2010 (UTC)

I don't see what injecting a contrast material has to do with it - that increases the opacity at the one wavelength you are using. I have no idea what it does at other wavelengths. --Tango (talk) 02:30, 6 January 2010 (UTC)

In general, I suspect it wouldn't be very interesting. At low energies there is a lot variation in x-ray cross-sections for different elements (it's the operating principle for energy dispersive X-ray spectroscopy), but at the high energies typically needed for penetrating x-ray scans there isn't much variation. Specifically, the high energy x-rays pretty much just scatter/attenuate in relation to the electron densities they encounter. Electron rich elements (calcium in bones, iodine or barium in x-ray contrasts) are more visible because they have more electrons, but they aren't really fundamentally different colors they way one can distinguish them in light. As one may recall, colors come from exciting electronic transitions that are typically a few eV. Once you start firing penetrating x-rays at 40-50 keV there are no more discrete transitions to excite, since everything is ionizing. Dragons flight (talk) 04:03, 6 January 2010 (UTC)

french spiderman

have they ever commited him? here in the us if they feel u did crime but will get a light settence they commite u instread becausse they can keep u there for a long time. —Preceding unsigned comment added by 67.246.254.35 (talk) 02:17, 5 January 2010 (UTC)

Alain Robert mentions many arrests but no involuntary commitment. I'm not sure your US description is fair but the reference desk is not for such debates. PrimeHunter (talk) 03:22, 5 January 2010 (UTC)

Who is "they"? Psychiatrists commit people, not the justice system. --Tango (talk) 03:25, 5 January 2010 (UTC)

In the U.S., involuntary commitment is a legal procedure, not a medical one. But I would like to see evidence that "they" commit people they think are going to get light sentences. 75.41.110.200 (talk) 05:24, 5 January 2010 (UTC)

The Pacific Gull's huge beak...

As far as I am aware, the Pacific Gull of Australia has the largest beak of any gull (it's almost puffinesque) and looking from the front, the gull appears to have a rather wide and muscular jaw. Now, I recall someone mentioning on here (may not have been on this desk, per se) that this bird has a very powerful bite, as might be expected from any large gull. What I'm curious about here is whether the Pacific Gull has a more powerful bite than other gull species of a similar size (say the Great Black-backed Gull, for example) - can it, say crack bivalves with its jaws that other gulls might have to drop from a height onto rocks/concrete to open? Can it tear flesh more efficiently? Can it carry larger amounts of food in its bill? Or is the size of the thing mainly for 'show' (I'm thinking of how a toucan beaks, whilst enormous and impressive are actually much less powerful than they look like they should be)? Any ideas? I've never personally encountered this gull, nor am I likely to at any time in the foreseeable future. --Kurt Shaped Box (talk) 04:02, 5 January 2010 (UTC)

A larger, thicker beak may protect it from fracture when subjected to greater forces, but strength would derive from larger or more efficient muscles of mastication -- I am unaware, though, of the avian set-up of such muscles. As a frequent science-question-related editor, I'm sure you're aware of this, but for the record, it should be mentioned overtly in the text of the discussion on this point :) DRosenbach ^{(Talk | Contribs)} 14:21, 5 January 2010 (UTC)

Tangentially related - why is there a Journal of Hippocampus but not a Journal of Gull Science? With such specificity in scientific publication, I would think that there should be an authoritative reference periodical for Kurt Shaped Box's various gull-related questions. What is the authoritative gull science reference work? ...is it Wikipedia/the Science Reference Desk?Nimur (talk) 15:07, 5 January 2010 (UTC)

Well, ever since we deleted RD/Seagulls.... — Lomn 16:54, 5 January 2010 (UTC)

If nothing else, you've provoked me to create Hippocampus (journal) -- which I should have done long ago, since my dissertation paper is published there. Looie496 (talk) 17:03, 6 January 2010 (UTC)

Which is more important in the grand scheme of things, would you say - gulls or hippocampi? --Kurt Shaped Box (talk) 22:20, 6 January 2010 (UTC)

Yeah, I'm aware of that DR - though I probably didn't make it clear enough. From looking at pictures of the Pacific Gull, it would appear that it is in fact wider in the face/head than other species of gull, which might be indicative of larger jaw muscles - but it's quite difficult to determine with birds, considering how they can puff up and deflate at will (I wonder what doing that feels like? Goosebumps - but consciously controlled?), significantly changing their apparent size and volume. --Kurt Shaped Box (talk) 02:22, 6 January 2010 (UTC)

Hi! Does anybody know the approximate biting force of a gull? I need it for a science project.

Power Curtain

What is a power curtain. I think they have them as a feature on vehicles.174.3.123.13 (talk) 16:11, 5 January 2010 (UTC)

Interesting...I could not find a single google hit in the top 20 or so that discusses automotive power curtains. The only reference to 'curtain' is in curtain-style air bags, but I hope that comes powered as a standard. Wouldn't be much use if you had to crank it open like rolling a window. DRosenbach ^{(Talk | Contribs)} 17:17, 5 January 2010 (UTC)

I saw several auto-related references in foreign (i.e. not US/UK) classified ads. As such, I expect it's a rough translation or perhaps idiomatic. I don't see overlap between "power curtain" and "power windows", so my best guess is that the two are equivalent. Alternately, it might refer to the partition between driver and passengers on a limo. — Lomn 19:04, 5 January 2010 (UTC)

I believe it's a power-operated side window curtain like the one in this photo. You get them on MPVs in hot countries, but not on small cars. --Heron (talk) 10:18, 6 January 2010 (UTC)

It may be a powered window curtain (or shade) as seen on many luxury vehicles, located on the rear deck to shade the back seat from sun. They extend and retract via motor. From the Google results, it sounds like they are quite failure prone (being electro-mechanical in nature). --Jmeden2000 (talk) 16:44, 6 January 2010 (UTC)

Impreza

What is standard-edition trim?174.3.123.13 (talk) 16:15, 5 January 2010 (UTC)

Note that the WRX STI you've linked is far from what many would consider "standard-edition"; however, you can find the specs of that model (and all others available) at Subaru's website. — Lomn 16:51, 5 January 2010 (UTC)

It says in lede, doesn't it (or is it a "newer" version)?174.3.123.13 (talk) 17:32, 5 January 2010 (UTC)

I just googled it, I didn't click on the article, so it may just be a cached version.174.3.123.13 (talk) 17:33, 5 January 2010 (UTC)

I suppose it's "standard" in that it's a mass-produced model, but the STI is the most expensive trim available (out of about 7, by my count) for the Impreza -- thus, it's not what I think most people would consider a "standard" Impreza. — Lomn 19:01, 5 January 2010 (UTC)

From nothing to electricity

A question purely out of curiosity:

In order to generate current, most power plants rely on some form of heat-generation which drives a steam engine which drives a dynamo which generates the current.

In order to make a dynamo, you need a magnet.

In order to magnetize materials, you need another magnet or a current (to produce an electromagnet which can magnetize the material).

So how did people get from naturally-occurring and presumably rather weak magnets to today's strong magnets? Is it possible to produce a magnet which is stronger than the magnet used to magnetize it (or stronger than the magnet in the dynamo used to produce the current used to magnetize it)? (obviousely the answer is yes, but how was it done? Did it involve large transformer circuits to get a higher current or something?) —Preceding unsigned comment added by 83.134.170.251 (talk) 18:53, 5 January 2010 (UTC)

Spontaneous magnetization. Dauto (talk) 19:08, 5 January 2010 (UTC)

Electric current and more windings. Or do you mean before electromagnets? Percussion —Preceding unsigned comment added by 75.41.110.200 (talk) 19:40, 5 January 2010 (UTC)

There are Lodestones, which are natural magnetic rocks. But actually magnets are usually created by electric currents, not by other magnets. The original magnets (except for Lodestones) were also electromagnets. To get the electricity they used a chemical battery a Voltaic pile, not a dynamo. Also you don't need a strong magnet necessarily to make a lot of electricity - you can also use a larger magnet, or spin it faster. Which will give you enough electricity to make any strength magnet you like. Ariel. (talk) 21:51, 5 January 2010 (UTC)

Just out of interest, big power station generators tend not to contain large permanent magnets. See Excitation (magnetic). Tonywalton ^Talk 23:16, 5 January 2010 (UTC)

Lots of turns of insulated copper wire around an iron horseshoe or other form creates a very strong magnet when a small electric current flows through it, far stronger than any natural magnet. These date back to the 1820's, and the work of William Sturgeon and Joseph Henry. There is no paradox such as the OP described, where only a strong magnet could create another strong magnet. Such an electromagnet can be used to magnetize steel or some alloys of nickel, cobalt and aluminum, or Neodymium to create amazingly strong permanent magnets. The current to power the early strong magnets came from zinc and copper plates dipped in dilute acid. Unmagnetized iron, weighing 59.5 pounds, became a strong electromagnet, capable of lifting 2063 pounds [1], just from the passage of a small electric current through thousands of turns of insulated wire around it. From the work of Michael Faraday, a coil moving past the gap of such an electromagnet has a voltage induced in it, giving the basis of the dynamo. One dynamo can furnish the power for its own coils, with the small amount of residual magnetism left in the iron being sufficient to start up the process when the dynamo starts spinning. By the 1890's the electromagnets used in generators were about 30 times more powerful than Henry's magnet of the 1820's. Electromagnets or field coils in generators today can be made even stronger. The strength of any natural or permanent magnets was of no importance in the development of these powerful electromagnets, nor are powerful permanent magnets needed to make the strong neodymium magnets sold today. Edison (talk) 23:10, 5 January 2010 (UTC)

For example, O +ve, and A1 -ve are rare types.

hi

Human blood group systems#Rare blood types:

A blood type is classified as rare when more than 200 donors have to be screened to find one compatible donor with blood of that type. In the "ABO" system, all blood belongs to one of four major group: A, B, AB, or O. But there are more than two hundred minor blood groups that can complicate blood transfusions. These are known as rare blood types. About one person in 1,000 will inherit a rare blood type. Whereas common blood types are expressed in a letter or two, with maybe a plus or a minus, a fewer number of people express their blood type in an extensive series of letters in addition to their 'ABO' type designation. For example, O +ve, and A1 -ve are rare types.

o+ve is Rare Blood type??????? —Preceding unsigned comment added by 212.77.204.150 (talk) 19:49, 5 January 2010 (UTC)

Formatted the original post for greater clarity. I agree that O +ve seems unlikely to be classified as "rare". Dragons flight (talk) 20:30, 5 January 2010 (UTC)

This wouldn't have anything to do with genetic linkage, would it? John Riemann Soong (talk) 20:46, 5 January 2010 (UTC)

The article was recently changed - I've reverted it. O+ is not a rare blood type, about 30-40% of people have it, depending on country (Blood_type#ABO_and_Rh_distribution_by_country). --Tango (talk) 21:17, 5 January 2010 (UTC)

Why are some metals more conductive than others?

I understand why metals are good conductors (namely a decentralized 'sea' of electrons caused by metallic bonding) but why is Silver, for example, more conductive than Gold? I'm guessing that it's at least partially related to the atoms electron shell structure given that copper, gold and silver are all in the same group but exactly why are some metals more conductive than others? I have't been able to find the answer anywhere I look, any help is much appreciated. —Preceding unsigned comment added by 95.150.243.104 (talk) 21:26, 5 January 2010 (UTC)

The "sea of electrons" model is an idealized version of what happens. In reality, all elements will exist on a continuum between a perfect, ideal "sea of electrons" model, and a perfectly "localized" model, where each atom retains its own electrons. So, every metal features some "localization" character along with the "sea of electrons" character; the better conductors have more "sea of electrons" character. Does that help? --Jayron32 21:57, 5 January 2010 (UTC)

These articles should talk about this topic, but some are better, or more complete than others: Electrical conduction, Classical and quantum conductivity#Classical conductivity, Drude model, Free electron model. (Actually most of those articles are pretty bad, but maybe the terms mentioned will help your find your answer in other places.) Ariel. (talk) 21:59, 5 January 2010 (UTC)

Thank you both very much, that's very helpful! —Preceding unsigned comment added by 95.150.243.104 (talk) 22:48, 5 January 2010 (UTC)

January 6

How the hell do people get AIDS?

While reading the article on AIDS I came across a chart the listed the chances of getting HIV based on a particular type of contact with an infected source. If the person I am having sex with has AIDS, I only have a 5 in 10,000 chance of getting it...and considering that the HIV infection rate in the US is less than 1 percent, it would mean statistically I could have sex with a random person 200,000 times before I get AIDS. I think there is a better way of saying this. Obviously I could get it after one time, but I think that statistically if I have unprotected sex 200 000 times, I would be just as likely to get HIV as not. So...how do people get AIDS??? Is everyone else just getting laid *way* more than I am? XM (talk) 06:50, 6 January 2010 (UTC)

The error in your assumption is that the distribution of HIV-positive people is uniform, when it clearly is not. Certain (cultural/ethnic/income/sexual orientation/age) subsets of any population have infection rates many times higher than the overall average. Conversely, certain subsets have rates many times lower. 218.25.32.210 (talk) 06:56, 6 January 2010 (UTC)

To make an extreme example - you could (probably) have all the unprotected sex you wanted with Mormon Octogenarians in Salt Lake City and never approach the likelihood of contracting HIV that someone in Sub-Saharan Africa has after one encounter. 218.25.32.210 (talk) 06:59, 6 January 2010 (UTC)

Look at it from the point of view of disease propagation. In order to spread HIV only needs to infect, on average, slightly more than one person for every person that it kills. Given that the median time to death for an untreated HIV infection is 10 years, most of which time is asymptomatic, it is not so crazy to think that an HIV+ person can manage to have enough sex to infect at least one other person. Add to that higher infection rates from the (mostly) historical problem of contaminated blood transfusions and the ongoing problem of sharing needles by drug users, and it it is not that hard to see why HIV continues to spread even though it does not do so very easily. There are about 40000 new HIV diagnoses per year in the US. There are also about 450000 Americans known to be living with HIV (according to the CDC). Given a ten-year prognosis, if they were all untreated, HIV/AIDS would have already come close to a standstill since about 1/10 of the known cases would be expected to die each year. So, we've made progress. Hopefully we'll eventually see new infection rates fall as well, but we aren't there yet. Dragons flight (talk) 09:20, 6 January 2010 (UTC)

why 5 in 10,000? Why not just say 1 in 2,000? (or is there some reason we can't reduce the fractions?) 194.221.133.226 (talk) 09:30, 6 January 2010 (UTC)

You can reduce it. It's just that the chart in HIV happened to scale everything in per 10000 event terms. Dragons flight (talk) 10:12, 6 January 2010 (UTC)

I would surmise that the robustness of your immune system has a lot to do with transmission probability. I mean, it's pretty obvious isn't it. :) Vranak (talk) 11:26, 6 January 2010 (UTC)

So this 5:10,000 (1:2,000) chance is per time you have 'normal' unprotected sex. If you do so at an 'average' rate of 2.5 times per week (I believe that's about the rate for humans in their sexually active years) then you're doing this 142 times per year. So your chance of getting the disease is now 1:14 per year. Over 14 years of sexual activity - you odds of getting the disease are close to a certainty. Do this experiment for me. Take two normal 6 sided dice. Roll them and add up the numbers. If it comes up '4' you just got AIDS...now roll them again - if it comes up '4' you get AIDS next year...keep rolling the dice. How many years did you get away with it? Of course, you could easily roll a 4 the first time...bad luck...you might get away your entire sexually active life without ever rolling a '4' but it's not really likely is it? SteveBaker (talk) 14:15, 6 January 2010 (UTC)

Also looking at the source quoted [2] 0.04% rises by a factor of ten-ish if your partner has started developing any symptoms, either of you had genital ulcers or it is male-male intercourse. I guess checking the gender of your partner is the onyl one of these you'll be sure of. The only friend I knew who was confident about the risks being small died in 1997 leaving a three year old daughter. --BozMo talk 14:30, 6 January 2010 (UTC)

To be specific, 1 in 2000 is the reported risk for a male to receive HIV from penis-to-vagina intercourse with an HIV positive woman. That last bit is highly relevant. If you limit your partners and have confidence in their disease-free status, then you can greatly reduce your odds of infection. Of course if you have sex three times a week with a different stranger each time, then your odds of infection go way up. Dragons flight (talk) 14:47, 6 January 2010 (UTC)

Additionally, circumcised males vastly reduce their chances of contracting HIV via sexual transmission because of the reduction of mucous membrane surface area. DRosenbach ^{(Talk | Contribs)} 23:49, 6 January 2010 (UTC)

I think it is important to emphasise that it reduces the chances, it doesn't eliminate them. (I know you didn't say otherwise, but I don't want anyone to misunderstand you.) --Tango (talk) 01:57, 7 January 2010 (UTC)

Properly using a condom of course reduces the chances even more Nil Einne (talk) 05:11, 8 January 2010 (UTC)

Climate Change and work done by Professor Cox at Princeton University USA

Perhaps Peter Robert Cox (apologies if I have the name wrong) of Princeton University USA could look at a global warming problem for me? It involves the spreading of the weight of the earth as we move around in space, our spinning, our magnetic field orbiting our sun. I put the question to Professor Cox, what happens to Earth, when our ice changes to liquid and the magnetic fields change? Where will the equator be? where will the 8 meters (i believe you mentioned as an estimate) of water level be? how many hundreds of millions of we humans will be effected? i.e. thats if we don't start to address the problem that many be no longer then a centry away from happening? When we go into the next iceage, where will the "new ice caps form? ...think thats enough for the moment haha.....have much more though.

Wouldn't the main problem facing the human race be the distribution of excess water as opposed to carbon emissions? first and foremost water distribution across the globe to dry but fertile areas of the land mass to enable the mass planting of forests and crops, that would not otherwise survive without the water. Wouldn't that be the first problem to tackle? By changing the effect of more water in our seas to a plus you then can tackle the continuing effects of carbon emittions through the use of the water? You could also address the sea level by redirecting rivers back inland, the mass closing off of rivers across the globe that flow into the sea (the greenies would hate me, but i'm one myself). Create inland canals, storage areas for water across the globe, redirect human population from the cities to the inland water storage areas. Create towns and cities where the water supply is. Also harvesting sea water from the oceans as the human water supply will lesson the impact of the melting of the icecaps. The more the icecaps melt the more the sun's heat will pentrate the earth,(less reflection) therefore the meltdown of the ice may occur faster then we estimate. I would appreciate it if you could let me know what you think. If you have time you may contact me at <email>. Regards I like you work todate. Barry Harrison <phone> —Preceding unsigned comment added by 203.51.38.97 (talk) 07:29, 6 January 2010 (UTC)

Phone and email removed from public post for the protection of privacy. Dragons flight (talk) 07:40, 6 January 2010 (UTC)

• Hello and welcome to the the Wikipedia Reference Desk. This is a free service intended to help answer visitor questions. Volunteer(s) will be along shortly to attempt to address the questions you asked. However, you should be aware that we do not have any special connection to Peter Cox of Princeton, and we do not generally forward questions to outside parties. In addition, answers to questions will be posted directly on this board and we do not generally provide answers by email or phone. Dragons flight (talk) 07:49, 6 January 2010 (UTC)

• The oceans cover about 70% of the surface of the Earth. If you want to reduce sea level by one meter, you would need to flood all the land to an average depth of more than 2 meters. The Greenland ice cap that will, if completely melted, cause about 7m of sea level rise, now is kilometers thick. What's more, all that extra water is unlikely to end up where you want it. There is no guarantee that now dry areas will receive more water (although some may). On the other hand, despite a higher sea level and likely higher overall precipitation, some areas may dry up further. --Stephan Schulz (talk) 12:26, 6 January 2010 (UTC)

Indeed - we have no connection to Princeton - if Mr Cox happens to be a Ref Desk volunteer (it's hard to tell with all of the psudonyms around here!) then he might answer - but the odds of that are pretty small! Let me break up your many questions to make them easier to address:

1. "what happens to Earth, when our ice changes to liquid and the magnetic fields change?" Firstly, the business of the magnetic field 'flip' is nothing to do with global warming. Many scientists believe we are due for such an event sometime soon because they have historically happened on average once every 300,000 years - and it's been 750,000 years since we last had one. However, the 300,000 years figure is only an average - sometimes the earth goes for millions of years without such a flip - so the probability of it flipping in our lifetimes is not very significant. So the two events are not correlated. However, when the magnetic field flips, it "briefly" (in geological time) turns off much of the earth's protection from solar radiation - which would be "A Bad Thing".
2. "Where will the equator be?" - right where it is now! Our compasses would all point in the opposite direction - but that doesn't affect the path of the earth around the sun or our axial tilt (which determines where the equator is). It's only the magnetic field direction that flips - not the entire planet. All of that water sloshing around also cannot make a difference - the earth is well over a million meters across and the sea level rise is "only" 5 to 20 meters - so this is a negligable change to the shape and balance of the earth - nowhere near enough to make an appreciable change to our orientation with respect to the sun.
3. "where will the 8 meters (i believe you mentioned as an estimate) of water level be?" - everywhere that is currently less than 8 meters above sea level. If you own ocean-front property...well, it's gonna be under 8 meters of water. If you live 100 meters above sea level - then the ocean will be closer - but you're not gonna get wet.
4. "how many hundreds of millions of we humans will be effected?" - That's hard to estimate. One problem is that we don't know the extent of the problem. The number "8 meters" that you are quoting is an estimate. Other estimates range from about 2 meters to about 20 meters. Clearly, the number of people who are affected will vary immensely between those two extremes. However, this word "affected" is a tricky one. When the climate changes, every human on the planet is "affected" somehow. So the answer is "All of us"...the real question is not "How many?" but rather: "To what extent?".
5. "i.e. thats if we don't start to address the problem that many be no longer then a centry away from happening?" - it's already happening. The polar ice is visibly reduced - polar bears are going extinct - glaciers around the world are vanishing. People living near large bodies of ice and snow are experiencing rapidly rising river levels - and will soon be witnessing dramatically reduced river levels when it's all melted. This is happening TODAY. Arguably the disaster that struck New Orleans with hurricane Katrina is at least in part due to global warming because the intensity of hurricanes is worsening.
6. "When we go into the next iceage, where will the "new ice caps form?" - Well, we might have been due for an ice age over the next few thousand years - but it's not gonna happen. Global Warming is not the kind of thing that causes ice ages!
7. "Wouldn't the main problem facing the human race be the distribution of excess water as opposed to carbon emissions?" - well, there are other effects too - that CO2 will dissolve in the oceans forming carbonic acid - so the acidity of the oceans will rise and that will have other deleterious effects. But certainly the most obviously apparent effect will be the rise in ocean levels. But the increased temperature is having other effects too - the migration of animals, the places where temperature-sensitive plants will grow is changing. There are many, many other effects that are not directly related to sea level rise. I very much doubt that we've explored all of the problems we're going to see - the world is just too complex for that.
8. "first and foremost water distribution across the globe to dry but fertile areas of the land mass to enable the mass planting of forests and crops, that would not otherwise survive without the water. Wouldn't that be the first problem to tackle?" - Sadly, no. The water is flowing out of the ice caps into the ocean. The ocean is very salty. When the ocean levels rise, that doesn't increase the amount of fresh water available for watering fertile areas of the world! To the contrary, the inundation by the sea kills off crops and makes it impossible to grow plants close to the water in flatter areas. There aren't many (if any) trees that grow well in salt water.
9. "By changing the effect of more water in our seas to a plus you then can tackle the continuing effects of carbon emittions through the use of the water?" - It's not a "plus" - it can't be changed into a plus. It's a gigantic minus! In fact, the rise in ocean levels results in lighter colored parts of the world being covered by darker colored water - that actually INCREASES the amount of absorption of heat from the sun and accelerates the entire process.
10. "You could also address the sea level by redirecting rivers back inland, the mass closing off of rivers across the globe that flow into the sea (the greenies would hate me, but i'm one myself). Create inland canals, storage areas for water across the globe, redirect human population from the cities to the inland water storage areas. Create towns and cities where the water supply is." - well, rivers flow downhill and empty into the ocean. When the oceans rise by (let's say) 10 meters - that's a lot like lowering the heights of all of the hills and mountains by 10 meters and making them shorter by whatever distance the ocean gets closer. That makes using rivers that much harder. But redirecting a long river is a matter of moving gargantuan amounts of dirt and rock...it's very difficult to do on a large scale. I don't think that's really a viable plan. Besides, the water has to go somewhere - even if humans use it, the waste water has to go somewhere. The amount of water produced by the melting of the ice caps is unbelievably huge - you couldn't remotely come close to digging enough lakes to hold it all!
11. "Also harvesting sea water from the oceans as the human water supply will lesson the impact of the melting of the icecaps." - not by any measurable amount. Again, even a modest 2 meter rise in ocean levels would require us to build (say) 12 meter lakes over half the surface of the land to hold it all - and dumping 12 meters of dirt and rock over the remaining half! It's a totally infeasible way to handle the problem. You have to get a grasp of just how huge the oceans are...they cover 70% of the earth's suface - when that much area increases in depth by even a few meters, the increase in volume is spectacular. The oceans cover 360,000,000 square kilometers - multiply that by 2 meters and you get 7,200,000,000,000,000 cubic meters of water. Seven million CUBIC KILOMETERS. Imagine a cube of water half a mile high by half a mile wide...that's a mind boggling thing...more water than a really REALLY large lake. Now imagine seven million of those. That's how much water we have to get rid of at a minimum. The worst-case estimate is for around a 20 meter rise - which is 70 million cubic kilometers. Digging 70 million vast lakes and redirecting our rivers to fill them is beyond crazy!
12. "The more the icecaps melt the more the sun's heat will pentrate the earth,(less reflection) therefore the meltdown of the ice may occur faster then we estimate." - yes, but scientists who are working on the problem are well aware of that issue. There are others that make matters worse too. Water (like most materials) expands when heated. As the planet warms up, the amount of expansion of the water in the oceans right now is enough to produce massive flooding - even if the ice caps didn't melt. Then there are a bunch of other effects - the possible melting of the deep ocean "methane clathrate" deposits - which would dump a bunch of methane into the atmosphere. Methane is an even worse greenhouse gas than CO2 - so that would make matters MUCH worse!

It's good that you're thinking about this - I wish everyone would do that - and ask questions about the bits they don't understand. SteveBaker (talk) 13:52, 6 January 2010 (UTC)

Regarding point 2, actually if you remove 20 m worth of sea level from Greenland and West Antarctica, the redistribution of mass is expected to shift the Earth's rotation axis about 500 m. Not much compared to the 40000 km circumference, but still very measurable and enough to have secondary effects on the distribution of meltwater. Dragons flight (talk) 14:25, 6 January 2010 (UTC)

Regarding number 6, one of the problems with many models of climate change and global warming is that they predict larger swings between climatic maxima and minima. In simpler terms, while on average the world may be getting warmer, there will likely also be greater variation between the hotter hots and colder colds; so that one symptom of global warming may be some "ice ages" of a few decades or a few centuries, followed in rapid succession by some very hot decades or centuries. Rather than gradual changes of slowly warming up or slowly cooling down, we may anticipate wild swings and unpredictable changes from year to year or decade to decade. The climate-change-deniers like to point at this sort of thing and say "See, you don't know what you are talking about, because you don't know whether its going to be warmer or cooler" Actually, that's kinda the point. In a world with stable atmospheric levels of greenhouse gases, then the system is more predictable. With the rapid changes in atmospheric chemistry we have been experiencing over the past century or so, the system becomes chaotic in ways that make it harder for us to prepare for it. See also Runaway climate change which touches on some of these issues, and also discusses some historical examples of periods in the past when we had wildly variable climate. --Jayron32 18:49, 6 January 2010 (UTC)

Regarding point 3: the extra increase in sea levels may well be uneven. You could have a semi-permanent sea surface height anomaly stretching from Jakobshavn Isbrae to Boston, for example. Changes in ocean currents would also affect local sea levels, as is the case in the Pacific where the sea levels are around half a meter higher in the west than in the east due to the Walker circulation and cold Humboldt Current. Global warming may well disrupt these ocean currents, causing more sea level rise than in others. Also, the effects of erosion from sea level rise, storm surges and tidal action could cause unstable cliffs to fall into the ocean, and the effects of subsidence in some areas will have an effect on this as well, while in other places isostatic rebound will negate most of the sea level rise. Seawater filling into large depressions will have the effect of temporarily displacing some of the rise in sea levels. Also, sea level rise estimates depend on the timescale on which the changes are forecast. Normally the forecast is for the next 100 years, and during this period sea level rise could be anywhere from half a meter to two meters, but "tipping points" could pass, for example the Greenland Ice Sheet (7 m) or the West Antarctic Ice sheet (6 m) collapsing that would result in higher sea levels in a relatively short amount of time.

Regarding point 4: if I recall correctly, a 10-metre rise in sea levels would displace roughly 640 million people based on present-day populations. Since much of the change will be occuring in developing nations, that number over 100 years could easily be far higher. Here is a map roughly showing the projected sea level rise innundation for units up to 14 meters, but "flooded" areas not connected to another flooded area that meets the present-day ocean will likely not be flooded at that sea level. Sea level rise is not the only threat, for there is also desertification, water/food shortages, and even resource wars that would displace more people. Billions of climate refugees is a distinct possiblity.

Regarding point 5: global warming is occuring now, and many thousands of species have already gone extinct. But we often don't hear about the human aspect of the damage, where in developing nations food and water shortages are already having an effect on populations. The Second Chadian Civil War and Darfur crisis, for example are sparked by water shortages. In Kenya, gunfights have broken out over evaporating waterholes and families have resorted to sending their daughters to prostitution as farming no longer produces enough food and charcoal doesn't make enough money. Right now, global ocean currents are slowing down due to a combination of climate oscillations likely stemming from global warming that have allowed cold Arctic air to flood deep into the interior of Northern Hemisphere continents. This situation is getting worse as the current state of El Nino progresses.

Regarding point 6: global warming is not likely by itself to trigger another ice age, but the shifting of ocean currents could easily plunge Western Europe into a much colder climate. However, another long ice age is likely inevitable, as Earth's orbit around the sun does not change, and we still undergo Milankovic cycles, and negative feedbacks are likely to take over once the driver of global warming, an increase in greenhouse gases, ceases to increse. Not to mention other possible effects like the eruption of the Yellowstone Caldera that would plunge the planet into a state of colder climate.

Regarding point 7: there will be on average more precipitation, but more of it will fall over the oceans and less over continental interiors. This threatens water supplies for many places around the world, for example around the Colorado River basin. The 2007 book Dry Spring (ISBN 1551928140) addresses this issue for a timeframe of within the next 25 years, mostly for North America.

Regarding point 8: see saltwater intrusion. ~AH1^(TCU) 00:08, 10 January 2010 (UTC)

Anti nuclear anti bodies

what is anti nuclear anti bodies? —Preceding unsigned comment added by 59.92.141.29 (talk) 07:52, 6 January 2010 (UTC)

See our article Antinuclear antibodies. --Thomprod (talk) 12:35, 6 January 2010 (UTC)

Rice type

Is there a rice or rices that will grow in salt marshes and moderate climate? 71.100.3.13 (talk) 08:06, 6 January 2010 (UTC)

Pokkali Rice grows in salt marshes, but I don't know how warm it needs the climate to be. --Sean 15:32, 6 January 2010 (UTC)

Rice also grows in Northern Ontario, I think. ~AH1^(TCU) 20:57, 9 January 2010 (UTC)

Physics and Chemistry

I'm in a joint physics and math undergraduate program now, but I'm thinking of switching into a joint physics and chemistry progam instead (this program is still primarily intended for physics students). I've done a quick googling of condensed matter physics (which the program intro lists as one of the areas falling within the intersection of physics and physical chemistry), and while it is apparently the most active area of research in physics, most of the work I've found seems to be experimental rather than theoretical, and I'm really only interested in doing theoretical work. But at the same time, it also appears that the same is true in other disciplines of physics, such as particle physics (although this may be due to the ineffectivness of my google-searching). Is it just me, or is there little important theoretical work left to be done in physics? If not, what fields of physics (other than string theory and the like) are active areas of theoretical research, and what sort of research could I look forward to if I went into physics and chemistry? Thanks. —Preceding unsigned comment added by 173.179.59.66 (talk) 09:29, 6 January 2010 (UTC)

From time to time it may seem that physics is pretty much all wrapped up and that "the great advances lie in the tenth decimal place" (anyone got a source for that quote?), but I think it's unlikely. The universe is bound to hit us with some big surprise some time soon. Quantum gravity still needs some work. — PhilHibbs | talk 14:51, 6 January 2010 (UTC)

A A Michelson, Light Waves and their Uses, University of Chicago, 1903. [3]. Michelson presented the quotation _as_ a quotation (that is, he appears to be quoting someone else), but there isn't a definitive source for an older version. "Sixth place of decimals", incidentally. Tevildo (talk) 18:00, 6 January 2010 (UTC)

There is theoretical work done in all areas of physics, and experimental work in nearly all areas. That said, a great deal of the theoretical work gets done by people that would generally be classified as experimentalists because their primary work is to collect new data and only a minor portion of their time goes towards developing the theoretical understanding of that data. True theorists, i.e. people who never manage experiments are relatively less common. My experience would suggest there are probably three or four experimentalists for every pure theorist. And its a distinction that has been muddied in recent years with the advent of computer technologies for theoretical modeling. Someone who designs computer models to predict the properties of new chemical compounds would probably be called a theorist though such a person might be closer to an experimentalist in many ways. There are several reasons that pure theorists are less common. For one it is harder. The easiest experimental projects are little more than exercises in applied technology, where one can produce useful science through the repeated application of straight-forward (though technically challenging) processes. That alone can be enough to justify a career if done well. By contrast, a theorist's career depends on developing a legacy of useful and novel insights. The path to doing that is far less obvious. Secondly, it tends to be easier to justify funding things than funding people (even though people can be considerably cheaper). For example, throwing a million dollars at the characterization of high temperature superconductors seems sure to produce something tangible at the end. By contrast, throwing $100k at a theorist to think about loop quantum gravity may or may not ever be useful. Even at the graduate student level it is much easier for experimental projects to offer financial support to students than for theorists to do so.

Because of such factors as those above, I would say that many students with theoretical leanings still end up getting involved in experimental work. And let's not kid ourselves, there is a lot of theory that can go into experiment design and data analysis if that is what one chooses to do. The kind of people that go into physics theory these days (with some exceptions) tend to be very talented mathematicians who coincidentally tend to be terrible at experimental work. There certainly still is a place for a people with a deep understanding of mathematics and birds-eye view of physics, but its not any easy field to get into or do well at. If you are dropping the math double out of a dislike for math (rather than say a love of chemistry) then you probably wouldn't much like modern theoretical physics anyway since it is extremely oriented towards mathematics.

You are right that condensed matter physics is an active area of research. In part this is because it has a relatively large number of near-term applications, far more so than more basic lines of research, and hence condensed matter can more easily attract funding from commercial interests looking for practical solutions in addition to the general funding available for basic research. Most theory done in condensed matter these days is probably of the computer modeling kind (i.e. predicting and explaining material properties through modeling). Deep theoretical insights, such as BCS theory still occur, but would be relatively rare.

At the intersection of physics and chemistry, in addition to condensed matter (see also physical chemistry, materials science), you also have problems in designing new compounds and synthesis processes (a subset of so-called chemical physics), and also applications to areas like biophysics and medicine with the understanding of cellular processes (you'd need to get involved with biology to go those directions). Dragons flight (talk) 15:17, 6 January 2010 (UTC)

First off, thank you for the swift and detailed response.

Now, I don't have an aversion to math at all, but I found some of the math courses I was taking to be a bit tedious. For instance, I had a class in algebra, dealing with fields and rings and so on, and I really couldn't see how it would have any application in physics, so I decided to drop the math part of my program. Right now I'm either switching into pure physics or phys and chem, and I would appreciate any imput as to which one I should pursue. And at the same time, I'm not reluctant to do experimental work, I just don't want to end up just doing experiments, in a way that detaches me from the real physics. Ideally, I would like to spend most of my time thinking about physics in an armchair with some paper and a pen, rather than filling in experimental holes. I looked into this chemical physics business, and from the wikipedia article it appears that this remains a field with theoretical questions to be probed. But looking at some articles published in chemical physics journals, it seems most of the practitioners are chemists, rather than physicist. Are either of these assements correct? Finally, these pure theorists you mention; are they found in all subfields of physics, or just in string theory, loop quantum gravity, and so on? Much thanks. —Preceding unsigned comment added by 173.179.59.66 (talk) 23:09, 6 January 2010 (UTC)

Well, first the bad news, field theories in the mathematics sense are massively important for cutting edge particle physics and string theory, and to a lesser degree quantum mechanics in general. Take a look at Standard Model and gauge theory. Now, of course, there is a lot of ground in the advanced theory of algebras that physicists never use, but the parts that do get used are essential and can get quite deep. In fact, Edward Witten, a leading string theorist was awarded the Fields Medal (the highest prize in mathematics) for the development of new mathematical techniques and theorems needed to understand string theory.

There are theoretical positions in all areas, but far more in the areas of string theory, particle physics (and its cousin particle astrophysics), quantum mechanics, and general relativity. In large part this is because these are areas that are highly amenable to further advancement through mathematics alone. If you really want to be a paper and pen type of theoretical physicist, then the easiest path is to master the deep mathematics relevant to one or more of the highly theory-inclined specialties. By contrast, areas like biophysics, geophysics, chaotic dynamics, fluid dynamics, and ultra-low temperature physics tend to skew towards experimentalists (though you can find theorists in those areas too). Things like condensed matter, cosmology, and thermodynamics are more intermediate.

With respect to the chemistry, I think chemical physics probably is more chemists than physicists (though certainly not exclusively so), and yes there are avenues for theoretical work. In principle, the foundations of chemistry are entirely described with early twentieth century quantum mechanics. In practice, almost no system involving more than two components can be solved exactly, so there is a lot of computational modeling and theoretical approximations in the hope of making useful predictions. And of course condensed matter added a whole further level of complexity. Being able to predict the properties of substances not yet synthesized is both an art and a science.

Personally, I would recommend figuring out what it is about physics that you love and follow that direction as much as you can. Making a career as a theorist is hard and competitive. Unless you love what you do it is unlikely that you will manage to put in the time and dedication necessary to be really good at it. Maybe chemistry does that for you, and maybe not. Maybe it is the mystery of the universe stuff, and you really should pursue string theory, or cosmology, or something. Or maybe you just like having interesting problems to solve, but don't really care about the field they are in (a not uncommon condition for physicists). In that case, you might consider leaving academia entirely; industries like management consulting actively hire physicists (at BS, MS and PhD levels) as technical problem solvers. It's much more lucrative but still caters to the urge to solve problems. Dragons flight (talk) 03:06, 7 January 2010 (UTC)

So are most physicists required to know a computer language or not? Sagittarian Milky Way (talk) 17:27, 6 January 2010 (UTC)

"Most"? Absolutely. Not all professors do, but it would be quite unusual for a new physics PhD not to be able to program at least within a scripting language like Matlab if not also in a compiled language like C++. Dragons flight (talk) 19:00, 6 January 2010 (UTC)

The article Computer literacy gives a good general account of what is expected. Cuddlyable3 (talk) 21:17, 6 January 2010 (UTC)

Regarding the original question, I strongly recommend taking a graduate level introductory quantum mechanics course before making a final decision, if you can. It's needed for just about any advanced theoretical physics or chemistry, and after taking it you'll have a much better sense of where you want to go. Looie496 (talk) 21:55, 7 January 2010 (UTC)

LMC/SMC Not orbiting Milky Way?

http://www.astronomynow.com/news/n1001/06SMC/

This article claims that "Astronomers have recently discovered that the Magellanic Clouds don’t orbit the Milky Way, but are merely passing through our neighbourhood with an entourage of smaller dwarf galaxies in tow." Can someone point me at the evidence for this please? --TammyMoet (talk) 11:04, 6 January 2010 (UTC)

http://arxiv.org/abs/astro-ph/0703196 Dragons flight (talk) 11:13, 6 January 2010 (UTC)

Thanks for this. From the abstract, though, there seems to be no support for Astronomy Now's assertion. Is there anything else? --TammyMoet (talk) 12:33, 6 January 2010 (UTC)

Sure - it's right there in the very first sentence of the abstract: "Recent proper motion measurements of the Large and Small Magellanic Clouds (LMC and SMC, respectively) by Kallivayalil et al (2006a,b) suggest that the 3D velocities of the Clouds are substantially higher (~100 km/s) than previously estimated and now approach the escape velocity of the Milky Way (MW).". If the Magellanic clouds are moving at anything close to the escape velocity of the Milky Way, they cannot be in orbit around it. Hence they will pass through our Galaxy and causing who-knows-what devastation along the way. Obviously, individual stars in each group will be disrupted in different ways - it could easily be that some of "our" stars will be captured by one or other of the Magellanic clouds - and that some of their stars will be captured by us - and all of the galaxies involved will have their nice symmetrical shapes splattered in all directions - but for sure the Magellanic clouds can't simply be in a nice gentle orbit around the Milky Way if they are moving faster than the escape velocity. But even at close to the escape velocity, there is no chance of a nice, clean orbit. A more appropriate term would be "train wreck" ! SteveBaker (talk) 13:06, 6 January 2010 (UTC)

Thanks Steve, but I still don't see how this means they can't be in orbit around the MW - even if it's a messy, chaotic and rapid orbit, it's still an orbit! And what about these "smaller dwarf galaxies"? What are they? They're not mentioned. I've not managed to find any dwarf galaxies which are recognised as being part of the LMC/SMC system. The SEDS page [4] gives about 4 globulars which may have been associated with the Canis Major dwarf, but doesn't mention any around the Magellanic Clouds. --TammyMoet (talk) 14:46, 6 January 2010 (UTC)

Escape velocity, by definition, means they're not in a periodic (or even pseudo-periodic) orbit. --Tango (talk) 14:51, 6 January 2010 (UTC)

What makes you think they will collide with the Milky Way? While they could have escape velocity towards us and will go through us and escape in the other direction, the abstract doesn't say that's the case and I would have thought it would mention it if it were the case. --Tango (talk) 14:51, 6 January 2010 (UTC)

To clarify, that's the paper with the unexpected measurements showing the LMC/SMC to be near escape velocity for the Milky Way (so possibly unbound). Everything else is probably the consequence of filtering the science through press releases and underqualified science reporters. Dragons flight (talk) 15:00, 6 January 2010 (UTC)

(sighs) I guess you're right there - I've had a good look round and can't see anything giving the Magellanic Clouds any entourage! I'm still confused though. If something is moving greater than escape velocity, that means it will escape the gravitational field of the larger object right? If something is moving slower than escape velocity, that means it will not escape the gravitational field of the larger object right? OK so they may not be orbiting us, but the lower-than-escape-velocity speed should mean they will eventually fall towards us, and be captured? It's interesting to see that many websites still claim they are satellites of the MW. Perhaps they're waiting for measurements which show that the direction of movement is not around, but through. --TammyMoet (talk) 15:13, 6 January 2010 (UTC)

If the speed is lower than escape velocity then they will be in a roughly elliptical orbit. The statement about them not being in orbit is just in the event that the speed is greater than escape velocity. If they are in a (psuedo-)periodic orbit then they are captured, that's what the words means, that doesn't mean they will collide with us, though - that would only be the case if the orbit is so eccentric as to make the perigalacticon (closest approach) less than the sum of the radii of the two galaxies, and I see nothing in the abstract to suggest that is the case. --Tango (talk) 16:08, 6 January 2010 (UTC)

However, it is likely that the two Magellanic Clouds will not escape the Milky Way's gravity by the time the Andromeda Galaxy collides with ours, so the combined gravity will likely be greater and draw in the Magellanic Clouds. ~AH1^(TCU) 20:50, 9 January 2010 (UTC)

catalytic dehydrogenation

Suppose I have a starting reagent that when dehydrogenated, has thermodynamic stabilisation because of aromaticity or extended conjugation of the product. Are there any selective reagents to facilitate oxidation or hydride transfer? If selectivity isn't a requirement -- e.g. it's a hydrocarbon, will bleach or hydrogen peroxide work? John Riemann Soong (talk) 11:22, 6 January 2010 (UTC)

There are several dehydrogenation reactions (especially easy if product is aromatic, for example cyclohexadiene→benzene; "aromatization" reactions should give you lots of literature hits), but I don't know of good catalytic ones. DMacks (talk) 17:41, 6 January 2010 (UTC)

I'm trying to design a transfer hydrogenation reaction... only I need to work backwards from most literature reactions (most people want to hydrogenate, I want to dehydrogenate). Does catalytic dihydroxylation with osmium tetroxide work with aromatic rings? I was thinking of a cyclodiene-like intermediate, with the expulsion of H2... maybe into a hydride acceptor like cyclooctatetraene. John Riemann Soong (talk) 23:55, 6 January 2010 (UTC)

OsO₄ doesn't easily touch benzene; RuO₄ might (heck, that oxidizes diethyl ether → ethyl acetate quantitatively!). But your whole process is confused by mixing up different types of "oxidation". Inserting oxygen is quite different than removing hydrogen. Searching for "catalytic dehydrogenation" gives many hits, there are many proprietary ways of doing it, which should tell you something about the ease of a novice getting it to work using simple chemistry or reverse-engineering an easy forward reaction. DMacks (talk) 16:49, 7 January 2010 (UTC)

Cursus honorum

Moved to Wikipedia:Reference desk/Humanities. --Stephan Schulz (talk) 13:20, 6 January 2010 (UTC)
The following discussion has been closed. Please do not modify it.
I see in the article cursus honorum there are various sequential steps and positions of public offices. Would it be fair to say these are the following and in this order? Military Tribune Quaestor Aediles Praetor Consul Proconsul Governor Censor Tribune of the Plebs Princeps senatus Magister Equitum (Master of the Horse) - 2nd in command (like a Vice President) Dictator From approximately what time range did this apply?--Doug Coldwell talk 12:53, 6 January 2010 (UTC) In what way is this a science question? Can I suggest you take this to the Humanities reference desk - the people there are much more capable of answering questions of a historical nature. All we're able to tell you is that the people who held these offices evolved from small shrew-like mammals and while in office they fully obeyed ALL of the laws of thermodynamics! SteveBaker (talk) 12:59, 6 January 2010 (UTC) What we can also tell you is that you should read your sources. In particular, Governor: "Though not part of the Cursus Honorum...". Also, a governor is usually a proconsul or a propraetor at the same time - one being a rank, the other a position. Censor: "After a term as consul, the final step in the Cursus Honorum was the office of censor" - which implies that all the later positions are not part of the c.h. In particular, as long as (non-thermodynamic) laws mattered, the plebeian tribune had to be a plebeian, while for quite a while the cursus honorum was reserved to aristocrats. --Stephan Schulz (talk) 13:11, 6 January 2010 (UTC) Yikes!!! I thought I was on the Humanities Desk. My mistake.....--Doug Coldwell talk 13:19, 6 January 2010 (UTC)

Spots on Betelgeuse, or just an imaging artifact?

APOD today has a nice picture of Betelgeuse. The text mentions the two bright spots, but it seems to me that there are bands of brightness across the image, some bands are horizontal and the others are diagonal about 30 degrees clockwise from vertical. Where these two sets of lines overlap, there are the bright spots. So, could the bright spots just be an artifact of the imaging process used? — PhilHibbs | talk 13:21, 6 January 2010 (UTC)

Possible, but highly unlikely. You're talking about an image that's been in the hands of numerous professional astronomers, including those who originally decided to construct the image. I think they'd know to account for imaging artifacts before claiming and publishing results. — Lomn 13:29, 6 January 2010 (UTC)

I agree with Lomn. Optical interferometry is very tricky business and requires considerable processing to get an image. What's more likely is either that the bright bands are an imaging artifact due to the (real) bright spots, or the bright bands are related to a real, but unmodeled, structure of the star. If you look at the journal article, the bottom panel of Figure 8 shows the sorts of artifacts associated with this interferometric image; a single point source would be split up into at least 5 spots with some streaks. The researchers don't just look at the image and decide what's there; they model a bunch of things might be there, subject those models to the same observational artifacts, and compare that to the data... whatever model best reproduces the data is their "answer" for what's on the star. The authors found a 2-spot model to work well, but freely admit that "Although the 2-spot model catches most of Betelgeuse surface brightness complexity and can be considered a fair description of the object spatial brightness distribution, going further requires even smaller and fainter details (as images in Fig. 8 show) thus probably showing the complexity of the star surface." -- Coneslayer (talk) 13:51, 6 January 2010 (UTC)

I see, so it is more likely that the bands are an image artifact caused by the spots than vice versa. Thanks. — PhilHibbs | talk 14:45, 6 January 2010 (UTC)

By the way, recent observations also suggest that Betelgeuse's diameter has shrunk 15% in the past 15 years. This could be an indication that the stellar activity is increasing and that a supernova could possibly occur in the near future. ~AH1^(TCU) 20:34, 9 January 2010 (UTC)

Decay

How have elements with relatively low half lifes not all decayed by now, considering the earth is 4.5 billion years old and before that no telling how long the elements were floating around in space 98.20.192.49 (talk) 14:02, 6 January 2010 (UTC)

Well, for one thing, you can have an element with a very long half life that decays into an element that has a short half life. The decay of the first maintains a supply of the second. -- Coneslayer (talk) 14:12, 6 January 2010 (UTC)

Similarly, other sources produce radioactive (and non-radioactive) isotopes. Carbon-14, for instance, is primarily generated by cosmic rays entering the atmosphere. — Lomn 14:15, 6 January 2010 (UTC)

Same with tritium which can be created by cosmic rays knocking bits from nitrogen nuclei. Googlemeister (talk) 20:59, 6 January 2010 (UTC)

But he's right; this is the reason that there isn't a lot of Californium in the Earth's crust. Comet Tuttle (talk) 20:43, 6 January 2010 (UTC)

Indeed. There are no transuranic elements with half-lives of more than a few million years (ie. about 1000 less than the age of the Earth) so there is no long-lived isotope that can decay into the shorter-lived ones, which means the shorter-lived ones are simply not found in nature. (There are some very minor exceptions due to very small amounts of those elements with the few million years half-lives surviving and the possibility of atoms increasing their atomic numbers through beta decay, but those just give isotopes in trace amounts.) --Tango (talk) 01:52, 7 January 2010 (UTC)

Muonic matter armour?

Could a stable, super-dense material ever be made of muonic matter or any other exotic atoms? And even if they were unstable, what if the muons were constantly replaced in the material (possibly made of normal matter) by some sort of "muon generator?" Also, is there any other form of exotic matter which might be a candidate?Trevor Loughlin80.2.193.221 (talk) 14:38, 6 January 2010 (UTC)

In any meaningful, grounded-in-science sense, no. There's nothing in the question that doesn't require firkins of handwavium. We also note that muonium behaves quite like hydrogen. — Lomn 15:14, 6 January 2010 (UTC)

It would take about 4×10²² W to generate 1 kg of muons at a rate fast enough to match the decay rate. For those keeping track all of human civilization uses about 1×10¹³ W. Dragons flight (talk) 15:27, 6 January 2010 (UTC)

We might need to work on the efficiency of our muon generator then. Googlemeister (talk) 15:55, 6 January 2010 (UTC)

Dragons flight has calculated a lower limit which assumes 100% efficiency. The lifetime of a muon is about 2 microseconds, which means replacing all of your muons half a million tmies each and every second. The energy equivalent of 1 kg of mass is about 9×10¹⁶ joules. Multiplying those numbers gives you your energy input per second (in watts) — assuming that all of the energy you put in is converted directly to muon mass. If you had access to that kind of energy (equivalent to detonating ten million one-megaton nuclear bombs every second) you'd be far better off pointing it at whatever was attacking you.

Incidentally, if you were able to generate all those muons, the wearer of the armor would almost instantly be incinerated by the heat from their decay. TenOfAllTrades(talk) 23:32, 6 January 2010 (UTC)

What if we make the armour spin around you really fast so the time dilation extends the lifetime? Or find some way to turn existing matter into muons, rather than creating them from raw energy? Or have very short wars? You just aren't being imaginative enough! --Tango (talk) 23:40, 6 January 2010 (UTC)

The energy cost for accelerating the shield up to a speed where time dilation becomes relevant is comparable to the energy cost of constantly replacing the muons. Plus, you're going to bleed horrific amounts of energy through synchrotron radiation. Again, if you had a way of accelerating significant masses to relativistic speeds, you'd be better off pointing them at the enemy. If pigs could fly, we could make flying pigs — but they don't. TenOfAllTrades(talk) 03:46, 7 January 2010 (UTC)

I think the centrifugal force would rip the armour apart long before it it reached relativistic speeds, actually. I was joking - I thought the final idea of having short wars (by which I meant wars of less than a microsecond) made that clear. --Tango (talk) 18:01, 7 January 2010 (UTC)

Flesh covered android?

Whilst the human-like intelligence depicted in the "Terminator" movies is quite a long way off being achieved, would an android covered with tissue engineered living flesh be possible with present day technology? And would this be within the reach of an amateur scientists using home equipment?Trevor Loughlin80.2.193.221 (talk) 14:46, 6 January 2010 (UTC)

Apparantly you can cut a cactus in half and then fasten it back again with a piece of metal, and the cactus still lives. So you could see if you could cover a robot in cacti perhaps. I do not know if you could combine cacti flesh from different cacti. Another possibility would be mould. Or do I mean mold? 78.146.51.13 (talk) 15:38, 6 January 2010 (UTC)

Not possible with current technology. It will probably take another 20-50 years of advances in biotech to get to that stage--not that there is actually any good reason to do it, though. Looie496 (talk) 16:33, 6 January 2010 (UTC)

Covering an android with human flesh seems like it might stall in the institutional review board phase. You would have to provide a pretty convincing reason why this would be a good idea. (If you're working alone in a garage, you can circumvent that kind of bureaucracy, at the expense of the support and organizational expertise that a large research institution provides). Nimur (talk) 17:30, 6 January 2010 (UTC)

Would "I want to build the most realistic sexbot ever - and we can all make billions off of this!" be a good enough reason? :) --Kurt Shaped Box (talk) 22:16, 6 January 2010 (UTC)

Only in Japan. --Tango (talk) 23:42, 6 January 2010 (UTC)

Only? Clarityfiend (talk) 02:28, 7 January 2010 (UTC)

There has been a lot of work on trying to make robots that look "human"—always with plastic flesh, though. The results are impressive though they are well inside the uncanny valley yet. The uncanny alley article has some links to such projects. --Mr.98 (talk) 17:59, 6 January 2010 (UTC)

If you want to use animal or human flesh then you would need the internal organs to keep the flesh alive. Vegetable or fungal flesh would be much more practical, as suggested above. For a fungal-flesh covered android, all you would need to do would be to cover the android in damp bread and let nature take its course. 78.146.51.13 (talk) 19:48, 6 January 2010 (UTC)

Current technology to use animal flesh on an android is not currently possible for the reasons state above, but some of the current test models such as eveR-1 have a pretty decent synthetic flesh. Googlemeister (talk) 20:56, 6 January 2010 (UTC)

This kind of question comes up once in a while in conjunction with the X-men character "Wolvarine" (whose bones have supposedly been replaced with metal). This is essentially the same problem that you are contemplating. The biggest problem is that bones are not simply inert lumps of support structure. They also are the source of new blood cells. Without proper bones - there is no way for blood to work - and without that, no flesh. SteveBaker (talk) 23:37, 6 January 2010 (UTC)

"Wolverine" and his bones weren't replaced, but rather partially coated, with the adamantium. How are we ever going to develop razor wielding super soldiers if we can't even cover the basics??? Of course, the question really is - where do the claws go when they retract? Having them sit on top of the bones of his forearm is ju-u-u-st this side of believable (for a superhero), but how they get through all his wrist bones is a bit tricky (or else his wrists should be about twice as thick as normal). Matt Deres (talk) 17:55, 7 January 2010 (UTC)

Special dreams

While dreaming, it is difficult to impossible to read. I heard rumours that some people can not even see colours in dreams. Mostly, it is difficult to recognize visual details. But then, there are dreams when reading is easy, when you can see and recognise every stroke of each letter. All details are (or seem to be) visible, colours are bright even exalting the waking state. Is there a name for that? 93.132.156.195 (talk) 16:36, 6 January 2010 (UTC)

Maybe Lucid dreaming or dreaming may have info for you. --Jayron32 18:35, 6 January 2010 (UTC)

Not really. Lucid dreaming is something different (being aware that so. is dreaming). While I myself, the most parts I can remember from those dreams, am aware that I am dreaming, the dreaming I described above holds elements especially uncommon to dreams that could mislead to take it for reality even more than common dreaming. 93.132.156.195 (talk) 20:19, 6 January 2010 (UTC)

Not sure of the term, but I have found that I can read in most of my dreams, but the part of the brain that is able to recall what I have read does not seem to work right when dreaming, so is it really considered reading if you can not remember it 15 seconds later? In any case, if a term for this has not yet been coined, perhaps you could write a paper and name the phenomenon after yourself? Googlemeister (talk) 20:53, 6 January 2010 (UTC)

I'd just call it a vivid dream. I used to meditate and visualise a lot when I was groing up and sometimes I used to have such vivid dreams I would remember details from them when trying to recall things that really happened. I sometimes actually found it difficult to say for certain whether a particular memory I had was of a dream or of reality!! This was mostly when I was groing up, it hasn't happened to me for a long time now. Vespine (talk) 23:06, 6 January 2010 (UTC)

Vivid dreams often occur in lucid dreams, and REM sleep may produce this type of vividity. However, I remember in some of my dreams that if I look away from the text, the text changes thereby making it difficult to read properly or recall what I'm reading. ~AH1^(TCU) 20:30, 9 January 2010 (UTC)

• Once I had a lucid dream that had the same vividity of reality. Obviously, take this as just a personal experience.--Mparu (talk) 16:18, 10 January 2010 (UTC)

Exploding olive oil

Earlier tonight, we finished a glass bottle of olive oil. Because it's prettier, we then refilled it from another, plastic bottle (of olive oil). An hour or two later there was a loud bang, and I went through to discover that the bottle had exploded, blowing the bottom clean off, and with a crack running along one of its corners (it's roughly cuboid-shaped). It wasn't near any sources of heat, and wasn't especially warm to the touch when I checked. What happened?! 94.168.184.16 (talk) 21:06, 6 January 2010 (UTC)

Well that certainly sounds pretty bizarre. About the only thing that I can think of is that the bottle had a knock when it was nearly empty, causing a small crack to develop and that when the bottle was refilled this caused the crack to propagate until failure occurred. You could look at the surface of one of the pieces of the bottle to see if there is any sign of an initial crack. Mikenorton (talk) 21:13, 6 January 2010 (UTC)

The culprit will most likely be either overpressure inside the bottle, or a temperature gradient that the bottle could not handle. From what I understand, olive oil has a high heat required to turn into vapor, so unless you were storing your bottle somewhere hot, like near a fire (you said this was not so), this would not seem likely unless your oil had a significant amount of some contaminant like dry ice (highly unlikely unless you regularly keep your plastic bottle of oil in deep freeze). That leaves a temperature gradient, which seems equally unlikely as that would also most likely involve a source or high (or perhaps low) heat. Only other idea I have is that there was some kind of slow chemical reaction between the oil residue, and the new oil. Honestly, I would hope not, because if I chose to eat both of those oil brands, I would not want that reaction to occur within my stomach. Googlemeister (talk) 21:34, 6 January 2010 (UTC)

Could a mouse have knocked it over? 67.243.1.21 (talk) 22:14, 6 January 2010 (UTC)

This doesn't answer your question but I regularly refill glass oil bottles (not because they are pretty but because I often by large quantitities in plastic bottles or cans and the smaller glass bottles are easier to use) including at least once IIRC an olive oil bottle with olive oil but have never had an explosion yet. I do usually clean and rinse the bottle and then let it dry properly first. Nil Einne (talk) 23:25, 6 January 2010 (UTC)

You said "wasn't especially warm". Does that mean it was warmed (or cooled) by something? Because that could do it. A square bottle might have some stress in it from the way it was manufactured, and maybe you hit it or something which released the stress. Check out Prince Rupert's Drops for a spectacular example of that. Ariel. (talk) 00:32, 7 January 2010 (UTC)

All I can say is that olive trees are revered in Greece and perhaps they and their fruits have some interesting properties as a result of being adapted to rather harsh, arid conditions. Vranak (talk) 11:38, 7 January 2010 (UTC)

It may have been due to temperature differences between the old and new oil, particularly if you kept the old bottle in the fridge and the plastic bottle not in the fridge. It may have been the air in the bottle warming up and expanding. (I do not know if oil changes volume with temperature). Or it may have been due to the glass equivalent of metal fatigue perhaps. See also Thermal shock and Liberty bell. 78.151.131.82 (talk) 21:06, 7 January 2010 (UTC)

• I agree; if you use cold oil to refill bottles, than you tap them and keep them at room temperature you will have an expansion causing an increment of internal pressure, wich may result in an explosion. Olive oil it is known to explode.--Mparu (talk) 17:30, 10 January 2010 (UTC)
  • By the way, here (in Tuscany) paesants use to sell olive oil using kilos instead of liters; this indicates that oil tends to vary its volume.--Mparu (talk) 17:34, 10 January 2010 (UTC)

Experiments in making ginger beer found that square cross-section bottles break easily from internal pressure. Polypipe Wrangler (talk) 02:52, 9 January 2010 (UTC)

butter churning

I watched "Catch me if you can" and was intrigued by the story about a mouse who fell into a pail of creme and churned it into butter so it could escape. It occurred to me, is it possible for a mouse to do that? In other words, what energy input is required to convert 2 liters of creme into butter, and is a mouse capable of supplying sufficient energy to do this before it drowned? For the purpose of this, we can assume a temperature of creme most charitable for the mouse provided it is between 5C and 25C. If this question is too complicated for a decent answer, what would be a good way to determine this experimentally without killing the mouse? Googlemeister (talk) 21:23, 6 January 2010 (UTC)

This isn't a particularly scientific answer but having whipped cream before (IIRC never by hand thankfully) and nearly churned it to butter too I highly doubt it. Particularly since it's likely to get harder as it churns it as the viscosity increases. In fact, I'm not even sure how it will work, all that will happen even if the mouse could do it would likely be a mouse stuck in butter (or more likely nearly butter) since I somewhat doubt the mouse could escape the butter once it is churned. More charitably, the mouse may not need to make butter. The surface tension of whipped cream may be enough for the mouse to escape so it won't have to churn it to butter, although I still doubt it would be possible.Nil Einne (talk) 23:19, 6 January 2010 (UTC)

My recollection of churning butter myself (I only did it once with a hand-cranked rotating barrel contraption - and that was a long time ago) is that its a long and exhausting process - I'm 100% sure a mouse couldn't do it. But there is another major hole in the story. When you churn milk into butter - you don't turn the entire volume of milk into solid butter - rather you separate the fat as butter from the water leaving a rather watery milk called "buttermilk". The butter forms little blobs that you have to skim out of the churn and squeeze to get rid of the remaining liquid. So the mouse (at best) dumps a lump of butter into the bottom of the churn and drowns in the remaining liquid. SteveBaker (talk) 23:26, 6 January 2010 (UTC)

Um, the butter will float not drop to the bottom. Ariel. (talk) 00:28, 7 January 2010 (UTC)

Yeah - just about...it's not very different in density than the buttermilk. But still - it's not one solid lump - you get bunch of loose curds that have to be scooped, drained and squished into a patty. Even a little mouse couldn't climb on it. SteveBaker (talk) 01:29, 7 January 2010 (UTC)

Actually, in many circumstances, you'll eventually get a single largish blob of butter rather than individual curds; they all agglomerate together, although the single lump will still contain entrained buttermilk that needs to be pressed out. The trick for the mouse, though, would be to manage to get to the top of the buttery island without the island capsizing and dumping the mouse back into the drink. I think the mouse would do better if it tried to climb out while it was all still very stiff whipped cream. ;-) Atlant (talk) 01:08, 12 January 2010 (UTC)

It did sound like one of those happy stories with a moral that has no scientific basis, but not having made butter (or whipped creme) I did not realize how difficult it was. Googlemeister (talk) 14:47, 8 January 2010 (UTC)

Palm Trees in Eastern Coast, USA

Where do palm trees start naturally growing on the US Eastern coast? --Reticuli88 (talk) 21:30, 6 January 2010 (UTC)

OR here, but I have seen them as far north as Norfolk/Virginia Beach, but those could have been planted and not natural, and the ones I saw did not look terribly healthy. Googlemeister (talk) 21:36, 6 January 2010 (UTC)

Palmetto trees grow as far north as Southeastern North Carolina. I'd guess that's about the northern limit. --Jayron32 21:37, 6 January 2010 (UTC)

It could be warmer temperatures due to the Gulf stream. 78.146.51.13 (talk) 23:16, 6 January 2010 (UTC)

Sound of sloshing water in home heating system

A week ago, the outside temperature fell to around 20-30 °F from being 30-40 °F the previous week. The heating system, which works through vents at the bottom of the walls, for my apartment stopped working in the middle of the night. I called my apartment manager, and I used a portable electric heater until the next day, when a repairman came and fixed the heating system. I have no idea what he did exactly since the heating unit is down in the basement, to which I have no access.

Everything seemed to be working fine -- the apartment is warm again -- except now whenever the heating system starts up (that is, when the temperature falls below the thermostat's setpoint), I hear the sound of sloshing water in the walls. The sound of sloshing water stops after a few seconds, but while the heater is running, I occasionally hear sounds that I would describe as perhaps a small brook or stream. I am sure I never used to hear these sounds of water before the heating system failed and was repaired.

Also, this I am not so certain about, but I think that the vents may take longer to get hot than they used to, and that when I touch the vents, the metal does not get as hot as it used to. But unlike the case with the sounds of water, I am not totally sure that the metal is less hot (I think it might be, but I am not sure) (even if the metal is less hot, the apartment is still being heated to the setpoint of the thermostat).

I don't see any water leaking anywhere. What do these sounds of water, which I never used to hear previously, mean? Do I need to be worried that something is wrong?

—Lowellian (reply) 21:34, 6 January 2010 (UTC)

If one has central heating with radiators (where water is pumped around a circuit to radiators in each room) then it's common for the plumber to introduce air to the system when working on it, which produces just the sound you describe. One can easily remove this by bleeding radiators with a special key. But it sounds like you have one of those naff blown-air heating systems popular in north america, so I guess it's air in the heat-exchanger pipes instead (and again it should have a bleed valve). Or it's ghosts. -- Finlay McWalter • Talk 22:33, 6 January 2010 (UTC)

If it's air, is this bad? —Lowellian (reply) 22:36, 6 January 2010 (UTC)

Not in moderation, it's just annoying. At least for the radiator-kind (and surely the other kind) there's a feed from the water main that tops off the water if any escapes (from leaks or plumbing-works), which fills the system up. Here is a page about bleeding radiators and here for here for system valves. But if it's an apartment then you might as well get the apartment complex handyman to do it (it shouldn't need a plumber). -- Finlay McWalter • Talk 22:47, 6 January 2010 (UTC)

You were not clear if you have radiators, or air heat. I'll assume radiators. Air is kinda bad because it can cause a slight amount of rust. But also air prevents the hot water from flowing properly, so the radiators would not be as hot. After service which opens the pipes (I'm going to guess he replaced the water pump) you will need to bleed all the radiators. Then after the system runs for a while (and the dissolved air comes out) you will need to bleed the radiators on the top floors. You need a special radiator key to bleed them, it has a square hole in it, and they are not hard to find, any hardware store should have it. Be aware after you bleed the radiators it takes a while for the pressure to build up again - usually you need a full off/on cycle. You might only be able to bleed half a radiator at a time. I'm very very surprised the service man did not say, or do, anything about it. BTW, if this is a multi-unit apartment, you will have to bleed all the radiators in the whole building to get rid of the noise, also if you don't your apartment will always be hotter than the others. Ariel. (talk) 00:00, 7 January 2010 (UTC)

When you bleed the air out of a radiator with the special key mentioned, air hisses out, then a little stream of water squirts out until you shut the flow off with the key. The system should automatically replenish the water in the room where the furnace is. A radiator that is not full of hot water obviously puts out less heat than one full to the top. Edison (talk) 20:12, 7 January 2010 (UTC)

Two more questions:

1. Will the presence of air pockets raise my heating bills?
2. Will this problem go away by itself (will the air escape on its own)?

—Lowellian (reply) 21:00, 8 January 2010 (UTC)

It might because the heating will be less even, so you might overheat one area because a different area is not getting the correct amount. Also heat transfer from the radiators will be worse. I would not expect much impact though, I'd be more worried about not having enough heat for the coldest days. Note: this is only if you have a lot of air, like half a radiator, a tiny amount at the top won't hurt (but probably also doesn't make noise). If the water level is really low, you'll have no heat at all.

The air will never escape. If it did it means you have a leak, and water would escape too.

That said, some systems have air removal devices. But they are installed near the boiler (in the basement), and since air rises, it will never get to the device. Those devices are meant for tiny bubbles carried along with the water. The don't help for large amounts. If they could have removed the air they would have by now.

Bleeding radiators is very easy. Just hold a paper cup, or paper towel (the water is black and metallic sometimes when it comes out) under the spout and open the key, listen (or feel) for the hiss of air, wait for water to spurt out, then close it, pause for a bit and do it again. It's easiest (most pressure) when the system is hot (but don't burn yourself). Ariel. (talk) 21:38, 8 January 2010 (UTC)

Well, the thing is, as I stated earlier, I don't have access to the basement. And my apartment manager would probably insist on anything being done having to be done by a repairman, so I don't want to insist on calling a repairman back if there's no real problem.

And here's the other strange thing: after the heater was repaired, for three or four days, I would definitely hear the sloshing every time the heater started, and I would also occasionally hear those brook/stream sounds I described earlier. And then, today or yesterday, those sounds stopped for the most part (the sounds do still occur from time to time, but much less than before). That's why I'm asking if the problem could have somehow fixed itself.

—Lowellian (reply) 00:31, 9 January 2010 (UTC)

You don't need access to the basement. The radiators are in your apartment. The water (air) levels in the various radiators has probably leveled out, so you don't hear the water moving around so much. And yes, some bubbles probably were removed by the air removal device I mentioned. I would still bleed them though, if you are willing to buy one of those keys (it's probably just a few dollars), it's very easy, and you don't need a repairman or anything. Ariel. (talk) 00:04, 10 January 2010 (UTC)

Possibly (assuming that it is a sophisticated system without normal radiators) there is some form of automatic air trap (at the highest point, up near the roof) to eliminate air, and this has now done its job, though there is still the risk of pockets of air being trapped unless the pipework is very carefully designed. Dbfirs 02:42, 10 January 2010 (UTC)

If there was such a device it would have removed the air by now. They work fast, and air rises immediately. Ariel. (talk) 06:09, 10 January 2010 (UTC)

... provided that the pipework is very carefully designed. Dbfirs 10:26, 11 January 2010 (UTC)

Life sensors

In Star Trek, the sensors can somehow detect the locations and numbers of living organisms. It can't be by heat or electric fields, because those can both be generated by natural phenomena. Is there any scientific plausibility to this? I'm aware that Star Trek is fiction, but many of the other concepts (phasers, antimatter fuel, etc.) have at least some scientific basis. --75.50.48.130 (talk) 22:13, 6 January 2010 (UTC)

Pheromones? CO2 emissions? The above in conjunction with either of these two? --Kurt Shaped Box (talk) 22:22, 6 January 2010 (UTC)

Real scientists look for the signatures of chemicals associated with life, such as methane on Mars. All that tells you is that there is (probably) life, and maybe how much, but not where, and not what. -- Finlay McWalter • Talk 22:36, 6 January 2010 (UTC)

(ec)These sensors are ridiculously inconsistent, even in-universe. The number of times that sensors detect life on a planet before the Enterprise or Voyager even reach orbit are too numerous to count. Yet, they seem to be totally unable to detect intruders, stow-aways, or others on board the same ship in numerous episodes. Rack it up to poetic license, grab a copy of the Nitpicker's Guide to `Trek, and forget about the details. Nimur (talk) 22:38, 6 January 2010 (UTC)

Telepathy and such work in Star Trek, so maybe the life signs detector is based on the same concept. Ariel. (talk) 23:54, 6 January 2010 (UTC)

StarTrek is about story, plot and characters. The technology is quite blatantly allowed to do whatever the story needs with little regard for science. If it's inconvenient for a character to return to the ship - there will be a transporter interference problem from some randomly named mineral deposits on the planet. If it's convenient to be able to transport someone aboard an enemy vessel, it works - if you wanted to beam a large nuclear weapon onto the enemy ship then you can't because you can't beam through shields or you can't beam at warp speeds...except when you can. Hence it's inconsistent, impractical and frequently impossible. Even the simple stuff like the communicator badges they all wear. Sometimes they have to tap the badge in order to place a call - other times they just speak. Ditto with answering calls. When they speak commands to the computer - it's not always clear that they are definitely talking to it. A system like that would result in a computer that picked up random orders from unintended bits of conversation all the time! But none of this matters because it's not that kind of a SciFi show. SteveBaker (talk) 01:24, 7 January 2010 (UTC)

The weirdest thing with the combadges is that they know who you are about to open a channel to before you say it, since the channel is already open and the intended recipient can hear you say "Picard to Riker" (or whatever). Now, that in itself isn't too strange - we know combadges can read minds otherwise the universal translator could never work - but why bother saying it if the combadge already knows? --Tango (talk) 01:43, 7 January 2010 (UTC)

That's actually not too big of a problem. See Buffer (telecommunication). The combadge could keep a 5-10 second recording, and when it hears a "connect" command, simply replays the recording of "Picard to Riker" over the com channel. Ambiguous commands to the computer are slightly more difficult to explain, but remember that Star Trek computers have highly advanced artificial intelligence systems. If you as an intelligent audience member can tell that the command was intended for the computer, then the AI probably would be able to too. That said, most of the Enterprise is usually run by highly powerful plot devices. -- 128.104.50.40 (talk) 23:16, 7 January 2010 (UTC)

I thought of a buffer but it seems to me that there is no buffer at least over long periods since they seem to respond very fast. In fact sometimes even over small intervals it seems there is no buffer. For example, if you say "Picard to Riker", Riker often seems to respond instantly (Riker here), this wouldn't work if the AI only plays back the message to Riker after you finish saying the Riker. Over longer intervals , I guess perhaps the computer slowly reduces the buffer. I don't know if the artificial intelligence in Star Trek is that great. Sometimes it shows some great ability, but for example it often needs to ask dumb stuff it should be able to guess or know or otherwise asks or specifies too much detail. E.g. if you want a glass of water it needs to ask what temperature and e.g. Data, one of the smartest AIs of all doesn't seem to be able to learn not to overspecify detail. There are better examples but it's been a while since I watched Star Trek. Nil Einne (talk) 00:43, 8 January 2010 (UTC)

There are real life life sign detectors. They are used to detect illegal immigrants hiding in the backs of lorries and work by detecting heartbeats (Google will find you details if you ask nicely). --Tango (talk) 01:43, 7 January 2010 (UTC)

Right, but they are looking for a different kind of aliens on Star Trek, most of the time. The device that the Enterprise is equipped with is called Everything_Sensor :) --Dr Dima (talk) 05:58, 7 January 2010 (UTC)

Why not just use visual cues? You can go with infrared, that's probably the most straightforward. Vranak (talk) 11:35, 7 January 2010 (UTC)

I read somewhere that if you could look closely at them one of the health indicators that move up and down in star trek is labelled 'Blue Cross'. :) Dmcq (talk) 14:07, 7 January 2010 (UTC)

[found it at imdb], it said 'medical insurance remaining. :) Dmcq (talk) 17:53, 7 January 2010 (UTC)

"Life sensors" did not detect life on Mars, but they didn't detect any in the deserts on Earth, either.[5] ~AH1^(TCU) 20:20, 9 January 2010 (UTC)

Reacting vicinal diols with formaldehyde hydrate (methanediol)

Or better yet ... methylene chloride ... can I count on the rapidity of intramolecular reactions and the driving force of distilling water to get a dioxy five-membered ring? John Riemann Soong (talk) 23:31, 6 January 2010 (UTC)

Also, all solutions I've seen of formaldehyde have been aqueous... essentially since the diol is acting like a protecting agent, how would side reactions be minimised? Is a solution of formaldehyde in methylene chloride viable, or do you have to use a protic solvent to prevent the formaldehyde from evaporating? John Riemann Soong (talk) 23:38, 6 January 2010 (UTC)

The 40% aqueous solution works. Or also you can use paraformaldehyde (no water, so you do not have as much equilibrium problem). If you really want water-free formaldehyde (either as the gas or dissolved in some other solvent, the usual way is by thermal cracking of paraformaldehyde—heat the solid in a still-pot, the gas comes out and you can bubble it into a cooled solvent, or even directly through your reaction mixture. A more efficient way is to start with dimethyoxymethane. A non-acidic way is to use dibromomethane with a base (S_N2 reactions). Beware, the methylene-acetal protecting group is very hard to remove. DMacks (talk) 16:43, 7 January 2010 (UTC)

January 7

what does antimatter look like?

Having just watched Angels and Demons, I was curious to know what antimatter would actually look like. In the film, CGI effects are used to show antimatter as a shiny, glittery substance. Is this in any way possible, as common sense suggests to me that it would either be black, colourless or invisible? If we could produce enough to be 'visible', what would we see? Also, could strong magnets as used in the film be used to hold it in place so as not to come into contact with matter? —Preceding unsigned comment added by 86.180.35.161 (talk) 01:21, 7 January 2010 (UTC)

I believe antimatter looks identical to ordinary matter. Appearance is determined by the charged particles in a substance and, apart from having all the signs reversed, the charged particles in antimatter are the same as those in ordinary matter, and changing the signs doesn't make any difference. It is certainly true that magnetic (and electric) fields are used to contain antimatter. See Antimatter#Preservation. --Tango (talk) 01:33, 7 January 2010 (UTC)

So put another way, antihydrogen would look like hydrogen. --Mr.98 (talk) 02:29, 7 January 2010 (UTC)

Antimatter looks identical to matter. And magnets will not affect antimatter any more (or any less) than they affect matter. (Magnets will affect a plasma.) Ariel. (talk) 02:44, 7 January 2010 (UTC)

However, the north pole of a matter magnet will attract the north pole of an antimatter magnet because the charges are opposite. --The High Fin Sperm Whale (Talk • Contribs) 04:34, 7 January 2010 (UTC)

That kind of depends on how you define north and south, but you're right on an atomic level the poles are reversed. But it would have no visible effect at a macro scale (unless someone manages to find a monopole). Ariel. (talk) 05:07, 7 January 2010 (UTC)

The charge carriers (positrons rather than electrons) in any electrical currents would have to flow the opposite way to get current in the same direction and therefore magnetic field in the same direction. For example if you had an electromagnet hooked up to a chemical battery, the antimatter version of that setup would cause the opposite magnetic field compared to the identical normal matter version. You would be able to tell that they were opposites if they were allowed to interact with each other. Rckrone (talk) 20:43, 7 January 2010 (UTC)

I think the point Ariel is trying to make is that the "north" and "south" poles are generally identified based on the macroscopic properties of the field. Hence anyone studying an anti-matter magnet is likely to label its north pole as the one that attracts south magnetic poles in other magnets. Such macroscopic labeling would require that the microscopic structure of an anti-matter magnet be spatially inverted relative to a normal magnet, but the microscopic details are generally invisible and need not affect which end of the magnet gets labeled north or south. Dragons flight (talk) 22:18, 7 January 2010 (UTC)

What about nuclear magnetic resonance? Will a photon that will excite an electron to a 40 kcal/mol orbital excite a positron the same way? John Riemann Soong (talk) 17:29, 9 January 2010 (UTC)

Antimatter in the presence of regular matter would look unusual in that stuff would be annihilating and putting out a huge amount of energy. But if it were contained so that that didn't happen and you were only interacting with it by seeing light reflected off it, it would look like normal matter. Rckrone (talk) 20:51, 7 January 2010 (UTC)

Reminds me of something from, i think, The Feynman Lectures. If you meet an alien who looks just like you and holds out his left hand in greeting—don't shake. He is probably made out of antimatter.—eric 23:32, 7 January 2010 (UTC)

Or your long-lost twin that's in the scouts... --Tango (talk) 02:58, 8 January 2010 (UTC)

Unless you are in a vacuum, that danger is pretty low. Googlemeister (talk) 20:38, 8 January 2010 (UTC)

duphaston tablet

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis or prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the talk page discussion (if a link has been provided). --Dragons flight (talk) 05:19, 7 January 2010 (UTC)

Virtual Reality?

will that ever exist?Accdude92 (talk to me!) (sign) 14:32, 7 January 2010 (UTC)

Have you read our article on virtual reality? It exists now. The degree to which SF-style VR will be implemented (and the timetable on which it will be implemented) will vary, naturally. — Lomn 14:41, 7 January 2010 (UTC)

The Holodeck article will be relevant, and it has a section of links to "similar technologies". I find it odd that the virtual reality article seems to be all about goggles and gloves, and I haven't found any article whose topic is the type of virtual reality that was hypothesized as "cyberspace" in Neuromancer. (The cyberspace article is about something else.) There's a Virtual retinal display article which is relevant to the Metaverse from Snow Crash. Comet Tuttle (talk) 18:00, 7 January 2010 (UTC)

It does exist - it's just a matter of degree. For example - in an advanced commercial flight simulator (especially at night) - it's very hard indeed to tell that you aren't "really there" - absolutely everything you can do, see, feel or hear inside an airliner's cockpit during more or less normal flight is simulated with close to perfect fidelity. However, the "free roaming" variety of VR where you're not strapped into a virtual vehicle of some kind imposes some extremely hard technical issues. The "goggles and gloves" issues can mostly be resolved. But the inability to be impeded by obstacles and the inability to walk around freely in the virtual world with the correct amount of inertia being applied to your body are both exceedingly tough problems to crack. SteveBaker (talk) 18:04, 7 January 2010 (UTC)

I would expect the walking anywhere problem but I would have guessed that the brain would have adapted to overlook the lack of inertia part. The brain is good at selectively ignoring part of its inputs. I thought that was part of the explanation of the flight simulator's limited motion appearing so real. 75.41.110.200 (talk) 22:03, 7 January 2010 (UTC)

Steve, I absolutely agree that the inability to be obstructed by objects is a huge problem. Less so on a walking around scale (People don't go around banging their heads against walls to check if they're solid, vision is enough.), but very much so on the "handling things with your hands" level. Some extremely elaborate and scary-looking force-feedback gloves have been invented, but they only solve the "squeezing" part of the problem. The larger part of being able to place your hand through a table is still unsolved, and causes no end of usability issues. APL (talk) 20:21, 8 January 2010 (UTC)

I don't know whether the brain would adapt - but certainly it certainly does not do so quickly. Our learned ability to balance when walking in a circle or stopping suddenly when running gets totally screwed up. I've tried both the "giant hamster ball" and "two-dimensional treadmill" kinds of machine - and they both sucked big time over 10 minutes of use. It just doesn't feel like walking (and in both cases, I was told in no uncertain terms not to even attempt to run!)...when you stop walking - you expect your body to lurch forwards due to inertia - so you unconsciously apply a backwards force to prevent that - but because you were never really moving, all that does is push you backwards. It feels just like walking along inside a bus or a train as it's accelerating or slowing down. Without handles to hold onto, you can't keep your balance. SteveBaker (talk) 23:01, 8 January 2010 (UTC)

I hope so, or I'm out of a job. "Goggles and Gloves" virtual reality absolutely exists. It's very expensive but is often used for military training, Maintenance training for expensive pieces of equipment and other things. Just recently I was at the I/ITSEC conference that had a variety of Virtual Reality systems. Including a very cool system where soldiers were running around a virtual building killing bad guys. (In reality they were running around in a large rectangle of motion tracking cameras.)

On the other hand, if killing bad guys isn't your thing, perhaps you could learn to weld. APL (talk) 20:17, 8 January 2010 (UTC)

I missed I/ITSEC this year (although my software was on show at the Total Immersion stand) - but from what I can see of the footage our guys brought back with them, there is a huge push to do more of this kind of thing. SteveBaker (talk) 23:01, 8 January 2010 (UTC)

Fronts

Why do fronts usher windy weather? How (without using a tv or anything, just by being outside) do you know when a front is on top of you? and why is it not windy when it is over you?Accdude92 (talk to me!) (sign) 18:01, 7 January 2010 (UTC)

As I understand it: A weather front is the boundary between two air masses of different densities. When you have two gases (or liquids) of different densities next to each other and are either moving or pushing each other, you get lots of instabilities (e.g. like Rayleigh–Taylor instability, or Kelvin–Helmholtz instability, or lots of other types), which produce all sorts of turbulence. That's your wind, in part. When you are no longer on the boundary line, you are no longer on that border line that is producing all of those instabilities (winds). As for how you would know if one is on top of you... I'm not sure you can do that without having some knowledge of the weather system as a whole. That is, you'd need to know the air pressure/temperature of a number of different sites, in order to say, "oh, there are two different bodies coming through here." Systemic weather knowledge as a whole generally relies on having more than just local weather information. That being said, some types of fronts are fairly obvious by the weird cloud patterns they produce, like a Derecho. --Mr.98 (talk) 18:25, 7 January 2010 (UTC)

(EC with above). Read Weather front for more information, but to distill it down to the basics, a weather front is the interface between two dissimilar bodies of air, usually a warm airmass meeting a cold airmass in some fashion. When airmasses of two different temperatures colide, several things happen:

• They generate convection currents, as the warm air rises over the cold air, and the cold air sinks below the warm air. The sinking, cold air generates high pressure at the surface (pressing down) and the rising warm air generates low pressure at the surface ("sucking" away). If you have two areas at a different air pressure, the air will move along the ground between the two of them, from the high towards the low, in an attempt to equalize the pressure. Hence "wind".
• Warm air has a higher dew point than cold air does; thus it has a higher "carrying capacity" with regards to water vapor. Just like when you breath hot breath on a cold glass, and you get little water droplets, when the hot moist air meets the cold, dry air, lots of little water drops form. Hence "clouds" and "rain"

These two effects happen any time you have warm and cold air meeting. The difference between a "warm front" and "cold front" and "stationary front" comes down to which air mass is doing the "pushing" and which airmass is being "pushed". If the warm is moving into the cold, it's a "warm front". If the cold moves into the warm, its a "cold front". Some more reading along these lines can be found at Surface weather analysis and, depending on how advanced you want to get, Synoptic scale meteorology. --Jayron32 18:29, 7 January 2010 (UTC)

There are several things you can look for that will tell you a front is passing you

• The Pressure drops and then rises again
• The wind shifts direction
• The wind becomes gusty and then turns calmer again
• The temperature changes
• Humidity changes
• Usually there is some precipitation

Dauto (talk) 19:19, 7 January 2010 (UTC)

The barometer was once the most important weather diagnostic and predictive tool, because it detected pressure changes associated with incident fronts and changing airmasses. In today's technological world of interconnected weather stations, NEXRAD doppler RADAR, and GOES weather satellites, we have other ways to predict and map weather changes and front systems; but you can still do a pretty good job predicting short-term weather with nothing but a barometer. Nimur (talk) 21:42, 7 January 2010 (UTC)

Look out your window. If you live in the plains you will often have a good long view of the approaching clouds associated with the front. 75.41.110.200 (talk) 22:00, 7 January 2010 (UTC)

A major process for why fronts cause precipitation is adiabatic cooling. Whether you have a warm front or a cold front, you basically get warm air rising over the cold air (no matter which air mass is stationary). If the warm air has a lot of moisture (especially on a hot summer day), that air has a LOT of energy. Think about it -- evaporation is an endothermic process. As that warm air rises, the pressure drops, the solubility of water in air falls, and the water condenses -- condensation is an exothermic process. But that makes the air parcel warmer than the surrounding air, and causes it to rise, and lose more water, which encourages it to be warmer than the surrounding air, so it rises, and loses more water ... wheee, positive feedback. When that air parcel eventually comes back down (often due to convection currents), the air mass will be much hotter and dryer than it started out. (This hot dry air might in turn encourage more evaporation at the surface....ooh look this strengthens the storm system and sustains the driving force for the accumulation of giant winds and big stormclouds! Wheeeee)

Another major thing that happens at fronts are convection currents. Different air masses at different temperatures will have differing pressures and densities. The cold air will be denser ... but that means its geopotential height for any given pressure will be shorter. The effect is that you get a high pressure area at the surface but a relative low pressure area in the upper atmosphere. So air flows from the cold air to the warm air at the surface, but from warm air to cold air in the upper atmosphere (e.g. at 500mb or 300 mb pressure). Think a big lake breeze (see the diagrams at sea breeze -- the thermodynamic forces at play are similar, just on a much larger scale). Now toss in concepts like the Earth rotating and other dynamics and you get sustained storm systems... John Riemann Soong (talk) 17:45, 9 January 2010 (UTC)

Think of fronts as the collision of two air masses: warm and cold, moist and dry. At the actual front, the warm air masses rise and the cold air mass sinks, creating an imbalance of temperatures, cloud formation, and wind. Also, sometimes instabilities within fronts may be enough for a section of the front to undergo cyclogenesis, as we have seen this winter. Since fronts are associated with low pressure systems, you have lower-level convergence of air masses that are separated by fronts. ~AH1^(TCU) 20:16, 9 January 2010 (UTC)

How do I change my ocular dominance?

Subject. HitmanNumber86 (talk) 18:04, 7 January 2010 (UTC)

Answer: Training. --Jayron32 18:18, 7 January 2010 (UTC)

Are there exercises I can do, or chemicals I can use? By the way, cite your sources, please. —Preceding unsigned comment added by HitmanNumber86 (talk • contribs) 18:27, 7 January 2010 (UTC)

Wear an eyepatch? 78.151.131.82 (talk) 20:50, 7 January 2010 (UTC)

Poke out your dominant eye? I'm not an expert but I'd say it's not possible to change it, unless maybe you are younger then 5. The visual cortex is one of the best studied areas of the brain so there probably is a good answer somewhere. I don't think the eye patch will work either. One thing I heard recently is that when a baby is discovered to have a lazy eye (Amblyopia), they put a patch on the strong eye. Unsurprisingly the weak eye's development gets strengthened and after some time it can be made to catch up and become pretty much "normal". However, surprisingly, to me at least, patching the strong eye does NOT weaken its development, even if the patch is worn for extended periods, like months, during early development. Vespine (talk) 21:18, 7 January 2010 (UTC)

This actually falls into the category of medical advice (intentionally or not), and we shouldn't be giving answers. Looie496 (talk) 21:40, 7 January 2010 (UTC)

I disagree. I wouldn't consider not liking your eye dominance to be a medical condition. --Tango (talk) 22:40, 7 January 2010 (UTC)

I wonder whether this might be similar to changing your hand dominess or Handedness which may be possible, but is problematic [6]. If you believe the " Consulting and Information Center for Left-handers and Converted Left-handers" extremely so [7] Nil Einne (talk) 00:25, 8 January 2010 (UTC)

Large Hadron Collider question

I just read some of Eric Johnson's document, The Black Hole Case: The Injunction Against the End of the World, and it is quite an insightful text, but I'm left wondering, if this machine is deemed unsafe somehow or another, who's got the power to shut it down? –Juliancolton | ^Talk 19:35, 7 January 2010 (UTC)

The chances of that happening is somewhere between zip and nill. Dauto (talk) 20:25, 7 January 2010 (UTC)

Still, the question of jurisdiction is an interesting one. --Mr.98 (talk) 23:11, 7 January 2010 (UTC)

Since the Large Hadron Collider is astride the French-Swiss border, part is within the jurisdiction of France and part within Switzerland, so I'm going to say "the authorities" in either country. Comet Tuttle (talk) 20:29, 7 January 2010 (UTC)

The CERN article says "As an international facility, the CERN sites are officially under neither Swiss nor French jurisdiction". It doesn't really explain what is the pertinent jurisdiction both for spectacular-death-by-physics matters, but also more humdrum stuff like office punchups and accidents in the workplace. -- Finlay McWalter • Talk 20:44, 7 January 2010 (UTC)

Thanks all. –Juliancolton | ^Talk 20:55, 7 January 2010 (UTC)

Here is a relevant quote from 2007, regarding the protocols that make CERN exist, by the CERN legal council:

The Protocol also grants us [CERN] immunity from jurisdiction of the national courts, to ensure our independence from individual Member States. Mind you, this doesn't mean we operate in some kind of legal vacuum: the Protocol requires that CERN settle its disputes by other means. This is why claims by the members of our personnel against the Organization should be submitted to the Administrative Tribunal of the International Labour Organization, and why conflicts between CERN and its contractors are decided not by the national courts but by independent experts appointed by the disputing parties.

...which seems like quite a legal tangle. --Mr.98 (talk) 23:11, 7 January 2010 (UTC)

At a political level, rather than a judicial one, I assume the member states have the authority to withdraw their financial support which would effectively shut it down. I imagine one could also play some legal chicanery such as the host nations asserting jurisdiction over the power lines that feed the site even if they don't have jurisdiction over the site itself. But to the legal question of what external party has the authority to order a work stoppage? I think the answer might be none. Dragons flight (talk) 23:26, 7 January 2010 (UTC)

Nice find, Mr.98. Since they have been set up as accountable to nobody, they are a sovereign; so I think the way to settle this matter is going to have to be an invasion by force, though of course the scientists have a supercollider as the main weapon on their side. Comet Tuttle (talk) 23:47, 7 January 2010 (UTC)

Actually Mr.98's note about lack of jurisdiction is already mentioned in the PDF that the OP cited in the first place. Comet Tuttle (talk) 23:52, 7 January 2010 (UTC)

Yes, looking at it closer, it goes over the jurisdictional issues pretty clearly. Page 49 of the PDF. --Mr.98 (talk) 00:07, 8 January 2010 (UTC)

I presume if another country is convinced it would destroy the world, they would also consider they are entilted to destroy it if diplomatic efforts fail. This technically means any soveign country but it seems likely only those who have a resonably chance of attacking and destroying it like the US, China, Russia, probably India and perhaps Pakistan, Israel and Japan (if they decide to remove their inability to launch a war and perhaps develop nuclear weapon) should be considered. Do note I've purposely excluded those from the EU who likely have an ability to shut it down without resorting to war. Presuming they are accurate in their belief, it seems likely such an attack would be considered justified under international law although this may not be enough to stop a counter attack. In reality, it seems rather unlikely any country would have to resort to such actions although the threat of war may or not be a useful part of their response Nil Einne (talk) 00:34, 8 January 2010 (UTC)

Did you say unlikely? I think that's an understatement. As I said above the chances are somewhere between zip and nill. Dauto (talk) 01:28, 8 January 2010 (UTC)

I think Nil Einne meaned it is unlikely a country would have to take military action in order to stop the LHC (because there are better ways to do it), not that it is unlikely the LHC needs to be stopped (which is, indeed, an understatement). --Tango (talk) 03:01, 8 January 2010 (UTC)

Well I think the chance a country will need to take military action even if it is necessary to stop the LHC is probably close to zip and nill too (it's not as if we're talking about North Korea here) which may have been what Dauto was saying. However it does illustrate a point. These countries by having the ability to take military action do have the power to shut it down since however they do it, they will be able to shut it down if they really feel it's necessary Nil Einne (talk) 05:07, 8 January 2010 (UTC)

Plastic bowl used in microwave

A nervous friend placed an old plastic bowl in a microwave and heated food.

When removed, the bowl was found to be entirely unaffected. Nonetheless, it was thrown away as a precaution.

She's worried that the bowl may have released harmful fumes that could continue to be dangerous in the future. Assuming the microwave is carefully wiped out, is there really any ongoing danger from future cooking? --Dweller (talk) 20:02, 7 January 2010 (UTC)

Your friend may have heard about the potential long term risk (a pretty low risk) of using plastics with certain carcinogenic plasticisers in contact with food. For this reason it's a good idea to use either pyrex or microwave safe cookware in the microwave. But the "danger" associated with a single use is negligible (and entirely taken by whomever ate the food) and there's no deadly cloud of killer gas lurking anywhere. If your friend had set the plastic bowl on fire and sat in the room while it burned down, that'd maybe carry the risk of smoking a few cigarettes. So no. -- Finlay McWalter • Talk 20:26, 7 January 2010 (UTC)

Could a knowledgeable editor add a discussion about this to our article section Microwave oven#Hazards? I hear a lot about this sort of concern — specifically, that molecules of some sort of biologically harmful plastic will leach into the food — but the only mention in our article is a concern that the plastic will melt. Comet Tuttle (talk) 20:43, 7 January 2010 (UTC)

Let me supply a link, instead of just jabbering: a Harvard Medical School article that discusses "microwave-safe" containers, and advises us against microwaving plastic wrap, water bottles, and several other plastic containers, because of concern about leaching the plastic into the food. Comet Tuttle (talk) 20:50, 7 January 2010 (UTC)

See Bisphenol A for a related plastic compound that is hazardous to health. ~AH1^(TCU) 20:08, 9 January 2010 (UTC)

Aqua Amino: "An energised vortex implosion" | Clean up your amino acid loading bays | Restore water to its original crystal structure

Today I bought this bottle of water at a leading chain-store here in South Africa, but I'm highly suspicious of quackery here, so much so that I think our regulatory bodies should maybe take this product down. It's called "Aqua Amino" [8] and appears as a bottle of mineral water, but on the bottle it makes several extremely interesting claims:

• How the process works:

Your DNA provides "loading bays" in your cells where nutrition is 'offloaded' to feed the cell.
The problem is, these loading bays get clogged up until they simply shut down.
Aqua Amino works at DNA level thereby providing your DNA with an optimal blue print to clean up your amino acid loading bays and enable effective amino acid delivery.

The result is a vast improvement to your daily health and renewed levels of vitality.
By allowing your nutrition system to be more efficient, your natural immune system operates at a higher level, providing near-perfect defense against impurities, viruses and bacteria.

• Before and After photo of the water

Aqua Amino is bottled at source in the Magaliesberg Mountains. Its purity is absolute but what sets it apart from other mineral waters is the gara system, a molecular mechanism that creates an energised vortex implosion. This implosion restores water to its original crystal structure, creating 'forgotten water'. The difference is clear, as shown in these pictuers that were taken at the E.F. Braun Wasserkristalle laboratory in Switzerland.

Does any of this sound legit? Rfwoolf (talk) 21:24, 7 January 2010 (UTC)

Not a drop of it. -- Finlay McWalter • Talk 21:29, 7 January 2010 (UTC)

Amazing stuff. Cuddlyable3 (talk) 21:47, 7 January 2010 (UTC)

Sounds like they're on about water memory, sorta. -- Finlay McWalter • Talk 22:04, 7 January 2010 (UTC)

To expand: water isn't a crystal, if you couldn't metabolise amino acids you'd die, if you drank something and it could interact with your (carefully husbanded) DNA you'd die, drinking water won't vastly improve your health unless you're dying of thirst, your immune system isn't materially helped by drinking anything (bar fixing obvious clinically-significant deficiencies), and drinking water won't give you "near-perfect defense" against anything. And this stuff is somehow "pure" yet also contains this impossible nanotechnological wonderstuff. -- Finlay McWalter • Talk 21:55, 7 January 2010 (UTC)

I can't find anything about a "gara treatment", so it's likely that they made it up on the spot. However, searching for "energized vortex implosion" returns this and several other quack products, leading me to belive that "vortex" and "implosion" are pretty common pseudoscientific words, that may have some specific meaning. (anyone who knows more care to elaborate?). The site linked above does reference what is undeniebly water memory. This is decidedly NOT spam. You should not by any of these products, from this or any other site. Buddy431 (talk) 22:32, 7 January 2010 (UTC)

Of those claims, only two are even potentially correct:

1. Aqua Amino is bottled at source in the Magaliesberg Mountains.
2. these pictures...were taken at the E.F. Braun Wasserkristalle laboratory in Switzerland.

Everything else is clear nonsense. (And the ice pictures don't demonstrate anything; they're just pictures of different-sized ice crystals.) TenOfAllTrades(talk) 22:37, 7 January 2010 (UTC)

E.F.Braun appears simply to be someone who takes rather nice microphotographs of ice crystals - http://www.wasserkristall.ch/ -- Finlay McWalter • Talk 22:41, 7 January 2010 (UTC)

I remember seeing a product with concentrated distilled water in it. Ariel. (talk) 23:13, 7 January 2010 (UTC)

I'm darned if I know what this paper is using? -- Finlay McWalter • Talk 23:17, 7 January 2010 (UTC)

Similar pseudoscience to Penta Water. Fences&Windows 23:55, 7 January 2010 (UTC)

Crystal water at room temperature? sounds like Ice-nine to me :) Dmcq (talk) 10:44, 8 January 2010 (UTC)

If I could make water that "worked at a DNA level" providing the DNA with "new blueprints" I would be a super-villain. APL (talk) 02:52, 9 January 2010 (UTC)

There are, however, many different phases of ice and crystal structures in water. Thesetwo articles may be of interest. ~AH1^(TCU) 20:05, 9 January 2010 (UTC)

Why do cold fingers get pruney?

I notice that when it's very cold outside, my hands look as if I've taken a very long bath. Why do fingers get pruney skin from cold exposure? --70.167.58.6 (talk) 23:09, 7 January 2010 (UTC)

There is a myth that pruney fingers after a bath is due to water being absorbed into the skin. This is not so, see: Wrinkle_(skin)#Pruney_fingers. So maybe cold is causing the same reaction in your fingers. Ariel. (talk) 23:29, 7 January 2010 (UTC)

That section talks about vasoconstriction, which does, indeed, happen in the cold, so that makes sense. --Tango (talk) 01:23, 8 January 2010 (UTC)

in vitro use of enzymes

I'm trying to see whether I can use tyrosine hydroxylase in vitro. I've looked up some of the literature and apparently I need to activate it with phosphorylating agents like various MAP proteins -- but apparently they're talking about E. coli transfection, and not like, running your enzyme on reflux in a test tube or something? John Riemann Soong (talk) 23:49, 7 January 2010 (UTC)

January 8

californium

The section Californium#Characteristics says: "One microgram spontaneously emits 2,314 million neutrons per second"

Is that 2.314 million per second, or 2.314 billion (Short scale) per second? (Comma is such a strange symbol to use for a decimal point.) And incidentally the ref it points to does not say. Ariel. (talk) 00:37, 8 January 2010 (UTC)

It should be 2.314 million per the ref on the top of page 3. Fixed in the article. Dragons flight (talk) 00:42, 8 January 2010 (UTC)

Chewing medicine capsules

Bottles of medicine capsules always say not to chew the capsules, but to swallow them whole. What would happen if one were chewed: would it be useless? Don't take this as a request for medical advice; I can't imagine why I wouldn't follow the directions and swallow them, even if everyone here says that it would help to chew them. Nyttend (talk) 00:56, 8 January 2010 (UTC)

I think the main problem is that you would get the medicine into your bloodstream too quickly. The capsules are designed to release the drug at a certain rate. If you increase that rate, you may be risk of overdose, but you'll also be at risk of the drug level in your blood dropping too low - when you take a pill every 4 hours that should maintain the level in your system within certain bounds, if you chew it you'll get a big spike when you take it and then it will drop really low until you take the next one. --Tango (talk) 01:04, 8 January 2010 (UTC)

Because of the Enteric coating. Ariel. (talk) 01:16, 8 January 2010 (UTC)

They may also release the drug too early, which could render it useless (eg. a drug that is inactivated by hydrochloric acid needs to be protected as it passes through the stomach). --Carnildo (talk)

Ah, yeah; at one time I was taking two medicines, and the doctor told me that I could take one (which came in capsule form) at virtually any time in a day because it released slowly, while I had to take the other one (a tablet) at specific times to ensure that I had proper levels. Nyttend (talk) 02:10, 8 January 2010 (UTC)

When you say you could take it at any time, did it need to be the same time every day? If you take it significantly less than 24 hours after the last one (assuming it was one a day) you would still have too much in your system even if it was releasing slowly, and vice versa if it significantly more than 24 hours after the last one. Issues with when you a take a drug are usually to do with whether or not you need food in your stomach when you take it. --Tango (talk) 03:24, 8 January 2010 (UTC)

I am sure most capsules will have bad taste. You tend to throw up weird testing substances before you can chew and swallow completely. manya (talk) 04:18, 8 January 2010 (UTC)

(OR) I once chewed a Tylenol Extra Strength Geltab and my mouth went numb with a horrible taste for about an hour and a half. It seemed as though the gel from the capsule couldn't be washed from the skin in my mouth. —Preceding unsigned comment added by 99.226.164.154 (talk) 14:59, 8 January 2010 (UTC)

Bacteria and Human feces

Does human feces have bacteria in it when push-out? Or is it still fresh when going to the sewage? And could you die/get sick if you ate it? —Preceding unsigned comment added by RadioActive697 (talk • contribs) 05:00, 8 January 2010 (UTC)

See coprophagia. Dismas|^(talk) 05:29, 8 January 2010 (UTC)

And as for the bacteria... see gut flora. Feces is nearly 60% bacteria. Eww. And it's of note that even if the bacteria weren't dangerous to eat (which it is), feces is a major vector for a number of diseases, like hepatitis, cholera, etc. Generally speaking, you don't want to be consuming feces.--Mr.98 (talk) 14:59, 8 January 2010 (UTC)

Although a couple of times I've suggested doing so to somebody. Looie496 (talk) 17:07, 8 January 2010 (UTC)

MythBusters did a test on the idea that flushing the toilet causes fecal coliform bacteria to disperse and land as droplets on your toothbrush. When they smeared both the used toothbrushes and the ones kept in a chamber away from use then smeared the samples with agar, all the toothbrushes had the bacteria...the myth was confirmed. ~AH1^(TCU) 19:56, 9 January 2010 (UTC)

Water/Hydroxylic acid

Why water is also called hydroxylic acid? Is water acid? --Qoklp (talk) 06:46, 8 January 2010 (UTC)

It isn't. It's called water. Sometimes you see bullshit/joke references to water as either "dihydrogen monoxide" (it's proper systematic name, but no one ever uses this name seriously) or hydroxylic acid. If named under the standard rules of acid nonmenclature, the name "oxylic acid" or possibly "hydroxylic acid" may apply as well, but no one seriously ever uses these names. Under acid nomenclature, the acid is named based on the anion in the acid; the cation of all acids is H⁺. So, if you consider water to H⁺ and OH^- (hydroxide ion), you could kinda-sorta consider it as "hydroxylic acid". Except that nobody, ever, not even the most pedantic of chemists, would ever call it anything except water. --Jayron32 06:51, 8 January 2010 (UTC)

Besides everyone knows dihydrogen monoxide and hydroxylic acid is simply greenie scare mongering and the proper name should be Hydrogen hydroxide] Nil Einne (talk) 12:32, 8 January 2010 (UTC)

Actually, Qoklp is right. Water is amphoteric (can act as both a base and an acid), and the auto-ionization of water is a very important concept in acid-base chemistry. Hydroxylic acid is technically a correct name, as is hydrogen hydroxide. ~ Amory (u • t • c) 15:40, 8 January 2010 (UTC)

Oh, they are all "technically correct" names for Water. It doesn't mean anyone at all actually uses those names. --Jayron32 19:10, 8 January 2010 (UTC)

Except in a joking context: see Dihydrogen monoxide hoax. Nyttend (talk) 00:33, 9 January 2010 (UTC)

Rainwater, for example, usually has a pH number slightly higher than 5, where 7 is neutral. ~AH1^(TCU) 19:52, 9 January 2010 (UTC)

Question related to Carbon-Capture and Sequestration

Resolved

The following question occurs to me as being one that could be used as an illustration. It probably has appeared before.

What would the entire atmosphere's thickness be if all of its component molecules were liquified?

Perhaps more difficult is to ask for the thickness if the atoms were rearranged ideally in solids, but maybe someone wants to take a shot at that as well.Julzes (talk) 08:17, 8 January 2010 (UTC)

About 10 meters. Dragons flight (talk) 08:21, 8 January 2010 (UTC)

(ec) The questions are actually easy. As you probably know, atmospheric pressure at sea level is approximately equivalent to the pressure of a 10-meter layer of water. If you could liquefy the atmosphere, the entire atmosphere thickness would therefore be 10 meters if the density of the liquid is 1 g/cm3. I don't remember what the liquid air density is, but I'll look it up now. The general result is: thickness = 10 m * 1 g/cm3 / rho [g/cm3] where rho is the density of liquid or solid air. --Dr Dima (talk) 08:22, 8 January 2010 (UTC)

OK, density of liquid air at 1 atm pressure is about 0.87 g/cm3, so the thickness of the atmosphere would then be 10 m * 1/0.87 = 11.5 m . --Dr Dima (talk) 08:25, 8 January 2010 (UTC)

(Edit conflict) Well, Earth's atmosphere weighs 5x10¹⁸ kg[9]. It's mainly 78% nitrogen and 21% oxygen. Liquid oxygen has a density of 1146 kg/m^3 [10], liquid nitrogen has a density of 811.6 kg/m^3 [11] put that together and you get: ((5x10^18 kg) * 0.78)/(811.6 kg/m^3)+((5x10^18 kg) * 0.21)/(1146 kg/m^3) = 5.722x10^15 m^3 [12]. Now you have a volume, and you need to convert it to a height above the earth.

You know, wolfram alpha has all these constants, but I can't quite get it to do the math for me without copy/pasting the numbers into a new formula. Ariel. (talk) 08:35, 8 January 2010 (UTC)

I see it's a bit simple. How about the question of changing all excess (anthropogenic) Carbon to diamond. How thick would that be?Julzes (talk) 09:38, 8 January 2010 (UTC) I'll ask the question I was about to ask at the mathematics desk.Julzes (talk) 09:47, 8 January 2010 (UTC)

Distributed globally? A layer 4 microns thick per year. Concentrated in one place that's 2 cubic km per year, that would be far more diamonds than have been collected in the entire history of the human race. (Of course it takes even more energy to convert the carbon into diamond, so no one would actually want to use diamond as a storage medium.) Dragons flight (talk) 10:07, 8 January 2010 (UTC)

There is no excess carbon. It's carbon dioxide. They are not the same thing, despite media and others being lazy and calling it carbon. It's not carbon offsets, it's carbon dioxide offsets, etc. Carbon dioxide can not be turned into diamond, although carbon can be. And BTW, there is a very very small amount of it in the air - about four hundredths of a percent, and the excess carbon dioxide amounts to 8 or 9 thousandths of a percent. Ariel. (talk) 10:25, 8 January 2010 (UTC)

Essentially less than a millimeter thick for the whole history? I see the math on localising it looks correct. It helps to actually do the math. Ariel, I think I and Dragons Flight understand what you're saying.Julzes (talk) 10:35, 8 January 2010 (UTC)

And, strictly speaking, it is excess Carbon I was thinking of. Since it accumulated due to the burning of hydrocarbons, that entailed some (I know) small decline in Oxygen in not only relative but also absolute terms. Dragons flight is almost certainly correct that the ideal method of precipitating out the Carbon from the atmosphere does not entail separating the Carbon and Oxygen atoms from each other (or Carbon and Hydrogen, concerning methane) and turning the Carbon into diamond, but it's a thought if clean energy were sufficiently cheap at the point in time at which geoengineering were to take place (probably a bad thought, but this was just an abstract curiosity exercise).Julzes (talk) 11:06, 8 January 2010 (UTC)

Actually we already have very cheap and plentiful devices that can remove CO2, there is no need for geoengineering. They are called plants :) And clean energy already exists too - it's called nuclear power (especially a thorium cycle, or a cycle using nuclear reprocessing, both methods leave almost no waste behind). The only reason we use hydrocarbon fuel is that it's cheaper. Ariel. (talk) 11:22, 8 January 2010 (UTC)

You don't sound like you understand the whole situation, but I don't feel like arguing. I got the answer to the question I was asking.Julzes (talk) 11:47, 8 January 2010 (UTC)

Whether it reflects understanding of the whole situation or not, I think that summary by Ariel was pretty much nail-on-the-head. As I've mentioned numerous times, the only obstacle we face with regard to climate change is socio-economic, not technological. There's a big bubble brewing around these parts with every upstart kid trying to sell some kind of new clean technology... but we already have industrial-scale, extremely clean alternatives to hydrocarbon. They are simply undesirable for economic and social reasons. There's no requirement to develop new technologies. Nimur (talk) 15:36, 8 January 2010 (UTC)

There is truth in that, and I think I understand your standpoint and what you're saying. Basically, I agree with the idea that we could probably get along quite well without developing fusion and some of the less ambitious energy technologies that are basically now in their adolescence. 'Could probably' is a key part of the last sentence, though. Global warming catastrophism is a perspective that shouldn't be taken as extreme, but rather as being within reasonable risk assessments. My own personal belief is that we should set the Carbon balance of the atmosphere precisely where it was when the industrial revolution took off. Since we can, and it probably would not really be that expensive relative to what we absolutely need to do; it would be a nice legacy to leave the future. Obviously, that's the future one step removed (the future of the future, one could say).Julzes (talk) 23:49, 8 January 2010 (UTC)

When I'm talking about risk assessment, I would consider not acting like a catastrophe could happen as being analogous to betting one's life for a million pounds on 2:1 odds in one's favor.Julzes (talk) 00:00, 9 January 2010 (UTC)

powering a stepper motor

Hello, I've disassembled an old DVD drive and have removed the motor that rotates the disc. It has three wires. I've figured out (with the help of an elementary cell) that they need to get pulses that are each out of phase by 120° (this is but a guess). In other words, each of the three wires must be pulsed one after the other, while the other two are connected to the ground.

Is there a simple circuit I could build in order to have the motor rotate? I'd rather build a circuit from discrete elements (individual transistors) than take an IC. I presume the circuit will be similar to that of a runnning light or something like that.

On a second thought, could I also use inductors?

—Preceding unsigned comment added by 88.70.81.101 (talk) 11:21, 8 January 2010 (UTC)

A three phase system is likely a servo motor not a stepper motor. In industry, such things are generally driven with three out-of-phase alternating currents with the phase velocity determining the rate of rotation. For hobby applications it probably is possible to drive it with a sequence of pulses (which would mimic the way stepper motors generally work). Analog circuit design is not really my forte, but hopefully someone else will be along to help. Dragons flight (talk) 13:36, 8 January 2010 (UTC)

PS. This page [13] gives a somewhat clearer idea of difference than our article does. Dragons flight (talk) 13:39, 8 January 2010 (UTC)

I basically need three "outputs" out of which, at any given moment, one is at a high potential and the other two have are at a low one, and they, like, take turns as to who's got to be "high" in this instant (like I said, running lights.) My question basically was, how to accomplish this... 92.226.94.41 (talk) —Preceding undated comment added 15:47, 8 January 2010 (UTC).

88.xx was me, btw. 92.226.94.41 (talk) 15:58, 8 January 2010 (UTC) The waveform doesn't matter, I think whether it's square or contiguous sine waves, both will do.

I think my two options are either a transistor circuit (which, for simplicity, would be effectively digital), kind of like a multivibrator with three, rather than two, cascades (stages) (is there even such a thing?), or something analog that uses inductors to make the the two other phases from one-phase AC. —Preceding unsigned comment added by 92.226.94.41 (talk) 16:16, 8 January 2010 (UTC)

Hi, it's me again. This is what I had had in mind: [14] Thanks anyone anyway. —Preceding unsigned comment added by 92.226.95.35 (talk) 19:26, 9 January 2010 (UTC)

Well water smell

What are some possible causes for a house's well water smelling like rotten eggs when it comes out of just one faucet in the house? Dismas|^(talk) 13:15, 8 January 2010 (UTC)

That whatever functional molecular group emits the smell of rotten eggs has been produced by bacteria that exist in the well water. DRosenbach ^{(Talk | Contribs)} 13:21, 8 January 2010 (UTC)

Rotten eggs is usually sulfur, in this case sulfur/sulfites are reduced to hydrogen sulfide. ~ Amory (u • t • c)

If the smell is really isolated to a single faucet, you can track the plumbing back to see where that plumbing line diverges from the rest of the supply. Presumably, the source of the contamination should be somewhere along that branch. I'd use caution if this is your potable water supply, as contamination could spread, with or without the smell, to other parts of your water supply. Nimur (talk) 15:31, 8 January 2010 (UTC)

According to your user page, you reside in Vermont. I believe the state health department offices located around the state offer very reasonably priced water testing. --Jc3s5h (talk) 17:33, 8 January 2010 (UTC)

On a tangent, the hot water in Iceland all smells of eggs due to geothermal heating. Fences&Windows 18:11, 8 January 2010 (UTC)

This link may be very relevent here. Many water softeners have sulfates in them, and often water systems have "sulfur-reducing bacteria" in the water, which turn the sulfates into sulfides, which stink like rotten eggs. Perhaps your softening system or pipes need some sort of treatment to get rid of these bacteria? --Jayron32 19:07, 8 January 2010 (UTC)

Here is the rest of the google search I used to find the above. There are dozens of links which say about the same thing. --Jayron32 19:09, 8 January 2010 (UTC)

Thanks, all! Dismas|^(talk) 03:29, 9 January 2010 (UTC)

Spectrophotometer operating manual?

Does anyone know where I can find an operating manual for a Varian AA-1275 atomic absorption spectrophotometer? I've already tried the manufacturer. The book's called “Atomic Absorption Spectrophotometers AA-1275 & AA-1475 Installation Instructions & Operation Manual”, but amazon doesn't have it. Nikkimaria (talk) 14:28, 8 January 2010 (UTC)

You may try posting your question over here. Have you tried ebay.com or craigslist.com? Perhaps there's a similar site for other physics-related devices and books, too? ···日本穣^? · 投稿 · Talk to Nihonjoe 06:29, 9 January 2010 (UTC)

Books about the creation of new breeds

Hi all, I would like to know if you could suggest me a book about the creation of new breeds; specific texts about breeding of dogs and fishes, and about interspecific hybridization procedures in general, are welcome, althought not strictly required. Thanks. --87.3.120.61 (talk) 14:48, 8 January 2010 (UTC)

Trabant automobiles and Umweltzonen

Why are Trabant automobiles not allowed in Umweltzonen? --84.61.151.145 (talk) 17:23, 8 January 2010 (UTC)

Likely because of their emissions by the looks of things. This site (http://www.motorhomefacts.com/ftopic-43830.html) has some info that might be of interest. I suspect the Trabant is in the red/yellow category and thus restricted in some zones. ny156uk (talk) 17:26, 8 January 2010 (UTC)

"Smoky two-stroke engine" according to our Trabant article. To my understanding that's an understatement. Looie496 (talk) 17:31, 8 January 2010 (UTC)

What is a "tail bridge"?

I just finished an article on Slauerhoffbrug ‘Flying’ Drawbridge which is described as being a tail bridge. I suspect that means that it is a drawbridge that only lifts from one side of the river or that it is a bridge that rests on only one side of the river. I've gone through countless Yahoo and Google links and checked several online dictionaries. In the whole scheme of things, this is not important, except for the challenge. Thanks for any help! GloverEpp (talk) 17:43, 8 January 2010 (UTC)

There is a type of swing bridge, known as a 'bob-tail' that is hinged off-centre, see [15]. The bob-tail refers to the concrete counter-balance weight that's required on the shorter end. Mikenorton (talk) 18:19, 8 January 2010 (UTC)

This link suggests that drawbridges with a counterbalanced tail (a 'tail bridge') are a relatively new development, taking up less space than more traditional designs. Mikenorton (talk) 18:28, 8 January 2010 (UTC)

Tris(pentafluorophenyl)boron + reducing silanes

AFAIK this mixture will reduce aliphatic alcohols into alkanes. Will it reduce phenols or catechols? John Riemann Soong (talk) 21:20, 8 January 2010 (UTC)

Ohm's Law

I was looking at the article on the drude model for the derivation of Ohm's Law, and I was a little confused about something. In the article, it says that the change in the average momentum = qEt, where t is the average time between collisions. But I would have thought that the change in momentum = qEt, and therefore the change in average momentum is half that, but apparently this is wrong. Can someone explain why? —Preceding unsigned comment added by 76.68.246.210 (talk) 21:26, 8 January 2010 (UTC)

The average in question is over electrons (really over "instances of electron acceleration between collisions"), not time, so there is no halving. --Tardis (talk) 21:46, 8 January 2010 (UTC)

If that's the case, then p represents the electron's momentum just before a collision, correct? In the article, the current density is expressed as J=qnv, where v is the electron's drift (ie average) velocity. Then it says that p=mv, but if p isn't the average (time-wise) momentum of the electron, then why should this relationship hold?

Sorry, I was quite a bit unclear, and saying "instances" was flat-out wrong. First, a general point: the average over time for one electron is the same as the average over all electrons at any one time (because the electrons are equivalent and so we can suppose the various electrons in a snapshot to be representative of the life experience of any one of them), and thus is also the same as the average over all electrons and all time. The average we are talking about is this common value (so it is fair, albeit unnecessary, to call it an average over time), and is perversely also the average of the momenta of electrons that are just about to collide. This last equivalence is not a universal truth but arises from the dispersion in intercollision times: if each electron always traveled for exactly τ time and then lost its momentum, it would have qEτ momentum at the end of each arc (and so the average would be that!) and the average over all electrons at any moment would be half that. But, at the moment you look, some electrons are in the middle of short arcs between collisions (so their non-noise momenta are very small) and others are in the middle of long arcs (so their momenta are large, possibly even larger than qEτ — even though, on average, you are seeing them mid-arc and so are only seeing half their "final" momenta). If we follow one electron around, the lengths of these arcs average to τ, but the electron spends more of its time in the long arcs (because they're longer!) and so skews the average in time/etc. upwards.

It just so happens that, with an exponential distribution of arc lengths (which is implied in the article, and should perhaps be stated explicitly), this effect doubles the average length of arc when you average over time/etc. (rather than collisions), and precisly cancels the (still-true!) fact that the average momentum we observe is only half of that that every electron will achieve at the end of the arc in which we observe it. This peculiar result is known as the inspection paradox or bus paradox. It lets us (for exponential distributions only!) say convenient things like "the average momentum is equal to the average time multiplied by the force" (which is where I drew the point that it wasn't an average over time, exactly). Put another way, and relying on the exponential distribution's famous memoryless property, we can look backward in time and say that the electrons in a snapshot have been flying free for an average of τ time, and so have on average the (unhalved)amount of momentum acquired during such a flight. --Tardis (talk) 23:09, 8 January 2010 (UTC)

Ahhh, okay I think I understand. Just a few things to clarify:

1) Is it easy to prove this property of exponential functions?

2) In the last sentence, what did you mean by "looking backward in time"...and why can we say that the electrons have been flying freely for an average of τ time? Is this because of the aforementioned property of the exponential function?

And by property, I'm refering to the arc length business. Thanks! —Preceding unsigned comment added by 173.179.59.66 (talk) 01:15, 9 January 2010 (UTC)

name of a littoral creature - nasty looking phallic thing

Hi - trying to remember the name of a creature that I think people dig up from the sand in the US/Canada? Maybe a foot long, or longer - looks like a brownish penis or tentacle - squirts sea water from one end - I think brave people eat them...

Thanks Adambrowne666 (talk) 22:08, 8 January 2010 (UTC)

Geoduck, kinda like a clam on steroids. It's pronounced "goo-ee-duck". --Jayron32 22:14, 8 January 2010 (UTC)

I love you guys. Adambrowne666 (talk) 02:36, 9 January 2010 (UTC)

Color preference vs. gender

Is there any particular reason why females like pink while males like blue or green more? Why is pink a feminine color? Every female in my family's favorite color is pink while the males are blue. 198.188.150.134 (talk) 22:43, 8 January 2010 (UTC)

It's genetic. Or it's cultural. -- Finlay McWalter • Talk 22:59, 8 January 2010 (UTC)

The evidence for it being "genetic" given in that article is either very poorly articulated, or extremely unconvincing. The sample sizes are blindingly small for such giant conclusions (37 people born in China get to stand in for "everybody who is not British"?). --Mr.98 (talk) 23:05, 8 January 2010 (UTC)

It's just what they've been acculturated to. Go into a store that sells clothing for babies — all of the boy stuff is blue and about dogs and trucks and all of the girl stuff is pink and about princesses. From day one—literally—kids in the U.S. (and probably elsewhere) are taught that pink is girls and blue is boys. Even if they don't get it at home, they will get it in their toys, their commercials, their friends. It has not been like this forever—our article on pink points out that the current practice dates only from the 1940s—which is a sure sign that it is not actually related to anything physical, any more than green means "go" and red means "stop". --Mr.98 (talk) 23:02, 8 January 2010 (UTC)

Up until the first bit of the 1900s, it was the other way around. Blue was seen as dainty, and associated with the Virgin Mary, while pink was a strong color, reminiscent of the very powerful red and hence appropriate for boys. ~ Amory (u • t • c) 04:13, 9 January 2010 (UTC)

Yes I'm pretty sure that's discussed in one or more of our articles, seems to be mentioned in one of the links above and has also been discussed here before and I would say that throws a spanner in the claim it's genetic. I haven't looked for a scientific article which the above researchers may have published but I too am dubious, particular about the part which attempts to use some people in China to represent different cultures which is problematic since the current cultural phenomon has AFAIK spread rather widely. For example, I know it's quite common in Malaysia. I doubt it would be very different in China. This could indicate some genetic basis or it could just indicate are very strong and wide ranging cultural phenomen. As with many things attempt to tell cultural phenomen from genetic, I would be much more interested in tests using people who have lived in some African or whatever tribe with little or no outside contact all their lives sadly such people by their nature are difficult come by and extensive testing on them likely raises many ethically issues. Nil Einne (talk) 06:49, 9 January 2010 (UTC)

Unfortunately I can't remember where, but I remember I read that pink became associated with girls because it resembled menstruations; so it's just a cultural issue. --82.61.166.182 (talk) 18:17, 9 January 2010 (UTC)

I think I read somewhere that blue (clothing? bibs? bedsheets?) was chosen for boys because it was a protective colour, and girls were thought to require less protection so a non-blue colour was chosen, therefore pink (but if this is a cultural thing then there would likely be variations). I also read somewhere years ago that pink in a room is a colour suited for sleep, and blue promotes more activity, but I'm not sure if that information is reliable. ~AH1^(TCU) 18:35, 9 January 2010 (UTC)

January 9

Instruments to track plate motions

Is GPS and satellites the only tool they use to track plate motions. I though GPS only does things perfectly accurate if the signal connection is good, to see things this far in blue ocean which things looks almost black, GPS will do more of a sketchy job. Do satellites do a perfect or a lusy job in low signal light block place? Is the tracking of plate motionperfectly accurates. Because all books I have all cites things differently.--69.226.34.161 (talk) 00:11, 9 January 2010 (UTC)

Nothing is perfect. Are you asking about Plate tectonics?

Also, GPS satellites work well both in the light and the dark, but they don't do well if the receiver is covered by a forest canopy. --Jc3s5h (talk) 00:17, 9 January 2010 (UTC)

I think that the OP is asking about tracking oceanic plates, where a sensor would be miles underwater (in the dark bit of the ocean). Indeed, GPS doesn't work down there. I'm sure geologists place markers on the seabed, but as there isn't a general deep-water positioning system, they'll have to revisit those with a surveying ship periodically and determine their position individually (with reference to the ship, and from there they can express that position in a general system like the GPS datum). -- Finlay McWalter • Talk 00:24, 9 January 2010 (UTC)

Ummm, if you want to know how an oceanic plate is moving, then you just track the islands. Dragons flight (talk) 04:05, 9 January 2010 (UTC)

Also the rate and direction of spreading at mid ocean ridges can be derived by using the magnetic reversal records contained within the ocean floor, which gives a pretty good idea of how the plates on either side have been moving over time. Continents are actually the hard ones, in some ways. Eve Hall (talk) 15:31, 9 January 2010 (UTC)

At a first approximation, tectonic plates are perfectly rigid, islands fixedly attached to them, and plates move only normally to the geoid. But if we're doing real science we can't rely on those assumptions, and need to actually measure the intraplate flexion (which this paper puts at up to 2mm/yr). The utility of island measurements is confounded also by the clustering of islands along the margins of oceanic plates, the least representative and least stable locus on the plate. -- Finlay McWalter • Talk 15:59, 9 January 2010 (UTC)

Talking about placing a yellow ball point object into the ocean. Then they have to use something so they will memorize where the ball point object was and years later they have to know where the object is traveling. This might be the best way to do a experiment, but I wonder if they can they can cause error bars.--69.226.34.161 (talk) 00:42, 9 January 2010 (UTC)

Laser ranging can also be used to identify precise locations. Graeme Bartlett (talk) 04:50, 9 January 2010 (UTC)

Also, when scientists measured the average ocean surface height after smoothing for waves and inter-annual changes, they found that sea levels were lower in places that were above oceanic trenches. Other movements such as isostatic rebound from climatic changes (even [[global warming) as well as large earthquakes, oceanic landslides and volcanic eruptions may have slight effects on the movement of crustal plates. ~AH1^(TCU) 18:31, 9 January 2010 (UTC)

putting Pluto back to planet status

Some rumors when I surf on internet said about putting Pluto back to being a planet. Have they plan to put Eris into being a 10th planet, since Eris is a bit bigger than Pluto What about Makemake will they ever qualify it as a planet?--69.226.34.161 (talk) 00:37, 9 January 2010 (UTC)

Planet status is arbitrary nonsense. Don't let they determine it for you if you disagree. Personally, I don't even consider Jupiter a planet. I find its immense size, strength of pull, and unavoidable presence more aptly described by the term mother-in-law. 61.189.63.173 (talk) 00:52, 9 January 2010 (UTC)

The IAU didn't get around to formally defining "planet" until 2006; see IAU definition of planet. Dwarf planet#Current members lists the five objects in our solar system currently considered to be "dwarf planets", including Pluto, Eris, and Makemake. Comet Tuttle (talk) 00:57, 9 January 2010 (UTC)

And the most likely time for them to reverse the 2006 decision would have been at the next general assembly in 2009, and the issue doesn't even appear on the agenda [16]. I don't think the IAU is going to change their minds about Pluto. --Tango (talk) 01:01, 9 January 2010 (UTC)

The thing to keep in mind is that the word planet does not belong to the IAU. Pluto is not an IAU planet. It's still a planet simpliciter. --Trovatore (talk) 01:04, 9 January 2010 (UTC)

Right, the IAU only regulated the technical usage of the terminology. As with any use of technical words, a term can have different meanings between being used technically and just colloquially (for example, bug). —Akrabbim^talk 01:13, 9 January 2010 (UTC)

You can still call it a planet in a technical sense, just not the IAU sense. They have no authority to regulate technical usage in general. --Trovatore (talk) 01:16, 9 January 2010 (UTC)

It is worth noting though that the major scientific and astronomical journals all require that IAU nomenclature be followed. So, you can do what you want in private (or even in public) but it would be virtually impossible to call Pluto a planet within the peer-reviewed scientific literature. Dragons flight (talk) 01:32, 9 January 2010 (UTC)

"The Sun orbiting object formerly known as ?" Would that pass? --220.101.28.25 (talk) 06:25, 9 January 2010 (UTC)

Besides that, the IAU does have the authority in so much as while people are free to do what they want, most people and most sources choose to follow them, i.e. they have de facto authority, whether Trovatore likes it or not. This of course follows many other areas of science, again whether Trovatore likes it or not. For example Trovatore is free to call element 105 hahnium if he so desires, it doesn't change the fact that most people have chosen to accept the IUPAC name despite the Transfermium Wars and call it dubnium of course. Similarly, Trovatore is free to call Callicebus aureipalatii as Callicebus madidii or if he wants to be controversial Callicebus wallacii (not sure if this would be the correct way to name it after Robert Wallace) or heck Callicebus robertwallaceisanidiot or Callicebus trovatoreissocool, but again it doesn't change the fact most people accept the International Commission on Zoological Nomenclature naming conventions which allow discoverer to choose the scienctific name within reason and following certain conventions which doesn't currently perclude them naming it after someone who won an auction and in this particular case, I doubt anyone would even know what the heck he is referring to. Nil Einne (talk) 06:38, 9 January 2010 (UTC)

In mathematics we get along just fine without any central authority deciding nomenclature. Other sciences should do the same thing. --Trovatore (talk) 06:43, 9 January 2010 (UTC)

Mathematicians also don't run around giving a unique and unintuitive name to every bug and space rock they see. The existence of recognized authorities for resolving naming disputes is highly beneficial to fostering clear communication in the stamp-collecting sciences. Dragons flight (talk) 09:15, 9 January 2010 (UTC)

In maths, we rarely refer to things solely by name unless they have been around long enough that everyone knows what you mean. You wouldn't just refer to a fairly new theorem by name, you would state the result in full. That is more practical in maths than in astronomy or biology (although it's far more practical in chemistry - every element already has a unique identifier, its atomic number). --Tango (talk) 16:37, 9 January 2010 (UTC)

Trovatore, I'm at a loss here trying to understand what's the point you are trying to make. You certainly don't mean to say that a math journal would accept a paper where someone tries to rename someone else's theorem to their own liking. The referees wouldn't accept that would they? Dauto (talk) 17:33, 9 January 2010 (UTC)

I don't know the details of the process, but I doubt the referees would care what the author calls the theorem. It's just a name, it doesn't make any difference to the maths. --Tango (talk) 17:34, 9 January 2010 (UTC)

I'm sure the referee's wouldn't let somebody rename a famous theorem. would they accept if somebody called fermat's last theorem by any other name? Dauto (talk) 19:35, 9 January 2010 (UTC)

Why not? Their job is to make sure the maths is valid, nothing else. With your example, I can certainly imagine people calling it Wiles' Theorem. Plagiarism obviously isn't allowed, but you credit people by referencing their work, not by naming theorems after them (see List of misnamed theorems). --Tango (talk) 19:47, 9 January 2010 (UTC)

The current definition for a dwarf planet is also very arbitrary, and should probably include far more than five members. Why doesn't it include the whole list, for example including Pluto, Eris, Quaoar, Ixion, Sedna, Orcus, Makemake, Haumea, Ceres, Vesta, Pallas, Juno, and even Chiron, not to mention the countless undiscovered planetoids, plutoids, plutinos, Trans-Neptunian objects, Cis-Neptunian objects, Kuiper belt objects (KBOs), detached objects and large, spherical members of the Inner and Outer Oort cloud? When you get to a small enough size, the definition of a dwarf planet tends to overlap with those of traditional asteroids and comets, or when you get far enough from the Sun the objects are too faraway to observe and may even fly off to the gravitational fields of other nearby stars and have too eccentric an orbit to be considered a planet. ~AH1^(TCU) 18:20, 9 January 2010 (UTC)

The definition of a dwarf planet includes the requirement that is be roughly spherical ("in hydrostatic equilibrium"). It is very difficult to know the shape of a distant object. If it is big enough we can be pretty sure it will be spherical, but for smaller objects it is hard to tell. That is why there are so many objects that might be dwarf planets but haven't been official designated as such. That could be considered a flaw in the definition, I suppose... --Tango (talk) 19:00, 9 January 2010 (UTC)

As with most words used in the sciences - we have different meanings from colloquial English. People talk about spiders as insects - and lots of people[17][18] don't think that birds and fish are animals. Almost everyone thinks that mushrooms are plants. People say that a car stops accelerating when you put on the brakes. You cannot regulate colloquial English - it changes over time - "Gay" used to mean "Happy" - it was once impossible for someone to be simultaneously "Cool" and "Hot" - but now, that's actually very possible. However, science needs precise, long-lived definitions for words. If you are writing a learned scientific paper about the genetics of plants - you absolutely don't want anyone assuming that you were including mushrooms in your work. So if you are speaking formally and in a scientific context then spiders aren't insects, birds are animals, mushrooms aren't plants and your car does indeed accelerate when you push on the brakes. Similarly, Pluto isn't a planet. However, a word is just a word. It doesn't mean that Pluto changed in any way - it just means that we took a vague, fuzzy term and made it more definite - and having done that, scientists started calling Pluto something different. Since we need exacting language, it is entirely appropriate that the leading body of some branch of science should issue a firm statement of what a word means in the context of their branch of science. However, in colloquial English, we can call it whatever we want. I bet that when NASA does it's next Pluto fly-by, you'll hear people there saying things like "We'll take a photo of such-and-such as we go behind the planet." - because in an informal context, that kind of sloppyiness is perfectly OK. But when you publish a formal scientific paper - expect the editors and peer-reviewers to complain like hell if you call Pluto a planet in that context. If you dug your heels in and INSISTED that that wording of your paper were not changed, then the odds are very good indeed that your paper would be rejected by the prestigious journals and conferences. But why should you give a damn? It's just a word. SteveBaker (talk) 19:55, 9 January 2010 (UTC)

I give a damn because I don't like organizations that arrogate to themselves the authority to specify how to use language. Language is supposed to evolve. It doesn't get decided by votes. In a scientific context, it gets decided by one contributor establishing a usage, and then others following that contributor, or else not. Doesn't have to be centralized, and shouldn't be.

IAU and IUPAC are particularly irritating on this score. IUPAC makes up silly names like ethene that no one has ever used, and took the plainly a-historical route on aluminium, a spelling that was invented not by its discoverer, but by a letter-writer to a journal, based on flawed reasoning. Not of course that any of that would matter if chemists in general chose to spell it that way; it just particularly sticks in my craw that this body decides to specify it that way.

My impression is that chemists in general don't take the IUPAC nomenclature too seriously. I don't think we should, either, at WP. In particular alumin[i]um ought to follow the usual WP:ENGVAR rules, even in chemistry articles.

That's what I think, anyway. I guess the chemists at WP have decided otherwise; not being a chemist, I won't stick my nose in it. But I think it's too bad. --Trovatore (talk) 20:53, 9 January 2010 (UTC)

"And the most likely time for them to reverse the 2006 decision would have been at the next general assembly in 2009, and the issue doesn't even appear on the agenda [16]. I don't think the IAU is going to change their minds about Pluto."

The other possibility is that the IAU simply doesn't care what name is given to what so long as the nomenclature is unambiguous (or at least, not as ambiguous as the word "planet" was prior to 2006).

In what way is that an "other possibility"? It doesn't seem to contradict what I said. --Tango (talk) 22:28, 9 January 2010 (UTC)

Unknown animals

I made this section once before, but no one answered before it was in the archives. What kind of owl is in File:Screech owl.jpg? I know it is a screech-owl (Megascops). --The High Fin Sperm Whale (Talk • Contribs) 02:39, 9 January 2010 (UTC)

The information with the picture says it was taken at "Seattle Zoo". If this means Woodland Park Zoo, Seattle, that Zoo's website [19] currently identifies their (only) Screech Owl [20] as a (one-winged) Western Screech Owl (Otus kennicoti). Obviously several assumptions here (identity of zoo, recency of photo, currency and accuracy of website) may be in error. 87.81.230.195 (talk) 07:00, 9 January 2010 (UTC)

Well, I know the zoo it was at has an aquarium built in too. And you could see Mount Rainier from it, as you can see in this shot. But it does look somewhat like a Western Screech Owl (Otus kennicoti). It wasn't missing a wing, but it was blind in one eye. --The High Fin Sperm Whale (Talk • Contribs) 23:36, 9 January 2010 (UTC)

exploding halo planets

Let's say hypothetically there was a dense halo of packed soil rotating around a sun, like a "band planet." Let's say it's radius was equal to the distance from the Earth to the sun, so gravity and whatnot is the same. Let's say it was concave so that water and stuff didn't run off into space. Let's also say that it had an atmosphere and everything.

Now let's say there were numerous explosions in one arc of the band, causing the destruction of a large amount of the band, leaving what was left only part of a band. Would the remaining part continue to rotate around the sun, and would it still maintain atmosphere? 169.231.9.45 (talk) 03:25, 9 January 2010 (UTC)

I would say that if the band (or Halo or Ring) was stable in one piece, it would now be very unstable. The piece could continue to orbit the sun, except if it was spinning fast enough in the first place to reach solar 'escape velocity'. Unless it was big enough for gravity to have an effect (seems unlikely) it would lose it's atmosphere. This type of 'band' is the subject of the Ringworld series of Sci Fi novels by Larry Niven. He covers these sorts of issues (and IMHO it's a good read). It's in Halo the video game too!

I'm not a rocket scientist so my answers are just based on general science knowledge, if I'm way off some nice editor (who is a rocket scientist Hi Nimur! ) will likely correct me. :) --220.101.28.25 (talk) 03:56, 9 January 2010 (UTC)

The closest sci-fi 'world' to this is Larry Niven's lesser known books: "The Smoke Ring" and it's sequel "The Integral Trees". The math to make these worlds work is complex and requires some really contrived set of circumstances to make them stable. Good books though...better than RingWorld, IMHO. SteveBaker (talk) 04:49, 9 January 2010 (UTC)

(edit conflict)
Having re-read your query & thought about this a bit more, I notice you don't specify how big the 'remaining part' is. If it was say half the entire band I believe it would have no stability and be likely to break up into many smaller segments, or even into rubble and dust. According to Ringworld it, hypothetically, "..rotates, providing an artificial gravity that is 99.2% as strong as Earth's gravity through the action of centrifugal force" at 770 miles/second. As one piece it may be a stable structue, but break it, imagine an aircraft propeller wih a broken blade. Dangerously unstable & Ringworld is made of a mythical material called scrith that is far stronger than "packed soil" or any know substance!
A 'small' piece thrown away from the broken band may survive intact, but would be likely to have a very elliptical orbit.
Thank you SteveBaker, I'll look those books up.--220.101.28.25 (talk) 05:07, 9 January 2010 (UTC)

I'm on a ski holiday in Truckee, California and I have limited internet access, but I can't leave a good question unanswered... In truth, band planets would probably be impossible if they were intended to be built as a solid material. The closest thing would be a planetary ring system - but those rings are made of individual particles whose orbits resonate with each other and with the planet they surround. When large chunks break off, they form shepherd moons, and through the magic of resonance, the ring re-equilibrates to a steady-state, lowest energy configuration. Any particles that begin to shear off, out of the ring system, get pushed back in by gravitational and tidal interactions to their original positions. Now, if your hypothetical band planet were not made of individual granules, but was actually a "solid" contiguous layer, then there would be a whole host of other problems. Such a configuration would be highly unlikely because it is both unstable and is not in the lowest energy configuration; it places huge hoop stress and other deforming shears and strains. Solving out the orbit equations quantitatively, we can calculate what stresses these would be - and invariably, it would require material properties that do not exist, in order to prevent being broken up (take a look at Roche limit). So to answer the OP's question, the band would already be broken up into individual particles; it could never sustain itself as a single contiguous piece of material ringing the sun, (despite the numerous instances in science fiction). Nimur (talk) 13:32, 9 January 2010 (UTC)

I think if the band was rotating at orbital velocity for its distance from the sun, and that distance was outside the Roche limit (which the Earth's orbit is), then it would be fine (over short time scales, anyway). To have gravity holding in air and water as the OP seems to want, though, would require having it rotating far faster. If you have Earth-like gravity, then it is basically the same as having a simple single-span bridge spanning 10¹²m - no realistic material is strong enough not to collapse under its own weight in those circumstances. --Tango (talk) 16:47, 9 January 2010 (UTC)

If the "halo planet" is solid material and the same mass as the Earth, you might end up with a band so narrow and thin that it probably would not support its own structure under the tidal forces it would create from its own rotation around the sun, and an atmosphere under such circumstances would be difficult to imagine because any single stretch of the "halo" or "band" would probably not have enough mass to hold on to air. Also, without an actual core, the "planet" would lack a magnetosphere, and the incoming solar wind would likely fry any atmosphere, water or life that was on it. ~AH1^(TCU) 18:06, 9 January 2010 (UTC)

The lack of gravity from mass is why you need to spin it really fast. If it is really narrow and thin and an almost perfect circle then there wouldn't be any tidal forces, although it would be in unstable equilibrium. --Tango (talk) 18:19, 9 January 2010 (UTC)

hybrid wind water turbine

atleast how much of energy can we approximately generate from a hybrid wind water turbine? —Preceding unsigned comment added by 121.52.146.85 (talk) 03:44, 9 January 2010 (UTC)

I think you're going to have to refine your question. Are you asking about a windmill used to pump water, which is then used to generate electricity (as proposed here)? Or perhaps you mean a turbine that can be used in either water or wind, like this one. Or do you just mean a windpump used to pump water out of a well? In any case, I imaging that the amount of energy produced depends on a variety of factors, including size of the turbine, and the conditions in which it is used.Buddy431 (talk) 04:34, 9 January 2010 (UTC)

Radon in milwaukee

Hey, its mee again. I have a projec t i need to do, and I need to know: Where are radon test samples sent to be tested in Wisconsin? THX —Preceding unsigned comment added by 76.230.208.196 (talk) 03:46, 9 January 2010 (UTC)

If it's in your water supply - then the Wisconsin Department of National Resources Radium FAQ (http://www.dnr.state.wi.us/org/water/dwg/radium.htm) says that you should contact the Wisconsin State Laboratory of Hygiene (http://www.slh.wisc.edu/) who point you to their testing department (http://www.slh.wisc.edu/ehd/testfee.dot) - who are going to charge you $68 for doing the test. SteveBaker (talk) 04:32, 9 January 2010 (UTC)

That's for radium, not radon. Information about radon testing in Wisconsin is available at http://dhs.wisconsin.gov/dph_beh/RadonProt/ —Bkell (talk) 21:38, 9 January 2010 (UTC)

Dark skies

Is there a name for the effect where the sky gets darker at very high altitudes? Astronaut (talk) 04:58, 9 January 2010 (UTC)

I believe it's called "atmospheric transparency". As there is more air between you and "outer space" when you are closer to sea level, there are more particles which can refract and amplify the effects of any light source, causing "light contamination" which causes the sky to appear brighter. As you go higher in elevation, there are fewer of these particles, as well as far fewer light sources (such as cities) which contribute to the distortion effect of the atmosphere, so the sky becomes more transparent and allows you to see the blackness of space more easily. It's similar to the difference between being at the bottom of a murky lake and being near the surface of the same lake: some of the light still gets through at the bottom of the lake, but the closer you get to the surface of the lake, the more clear the water becomes. ···日本穣^? · 投稿 · Talk to Nihonjoe 06:20, 9 January 2010 (UTC)

See Sky#Sky luminance and colors and Rayleigh scattering#Reason for the blue color of the sky. Dolphin51 (talk) 12:14, 9 January 2010 (UTC)

The electronic structure of anhydrous oxide crystals

A long long time ago, a professor told me there was no such as an O^2- anion (that is, an oxygen anion with a -2 charge) - it would spontaneously decompose into an anion radical with -1 charge and a free electron, and this was reflected in the electron affinity equations. If oxygen doesn't have a second electron affinity, then prolly no other atom would.

So then what does the electronic structure of compounds like zinc oxide, magnesium oxide, calcium oxide, strontium oxide actually look like? The crystal lattices aren't showing me things like electron density. I'm thinking actually magnesium forms a polar covalent donor bond with oxygen, so rather than (for a unit cell) Mg2+ O2-, it's actually Mg+ --- O- . Carbonyl'ish to the extent that maybe Mg=O is a contributing resonance structure? And then the unit cells would "link up" in this dipole fashion to delocalise some of this concentrated charge.

I'm thinking that the further down you move the periodic table, the less strong this polar covalent bond is, and basically the more radical-like the component ions (since it's impossible for oxygen to be a dianion all by itself), so basically why MgO reacts less violently with water than say ... strontium oxide, and why magnesium hydroxide is a weaker base than strontium hydroxide is? John Riemann Soong (talk) 05:16, 9 January 2010 (UTC)

dissolving sodium in water ... a pentuple enthalpy whammy?

• The redox reactions of sodium with hydrogen and oxygen are exothermic, e.g. the formation of H2 or Na2O.
• The combustion of the liberated H2 in oxygen (dissolved or in the air) to form H2O is exothermic.
• The conversion of NaH and Na2O into NaOH and H2O (of varying stochiometric amounts) is exothermic.
• The solvation of NaOH in water -- without any other acid-base reactions occurring, is exothermic. (As well as the re-condensation of the formed water-vapour...)

Then we also have the fact that there's an entropy of solvation contribution involved .... but is this insignificant compared with all this exothermicness?

If the NaOH actually reacts with something, like say, HCl ... then this is a fifth enthalpy contribution. (Say, that makes me curious... what happens when you dissolve sodium in an acyl chloride?? Or even just an aldehyde, ketone or an ester?)

Has anyone ever done a sort of "separated itemised accounting" for all of these contributions...? I'm just curious what the figures are. John Riemann Soong (talk) 05:25, 9 January 2010 (UTC)

Vitamin E

What is the difference in bioavailability between tocopherol acetates (i.e., from the solubility) and natural tocopherols? 99.62.185.39 (talk) 06:29, 9 January 2010 (UTC)

I don't have any empirical or quantitative data, but since it basically makes it more fat-soluble (the alpha-tocopherol is the most-fat soluble), I would expect bioavailability would increase? John Riemann Soong (talk) 07:31, 9 January 2010 (UTC)

The molecular species (alpha, etc.) may affect solubility much less than the anion. I suspect, also without empirical or other data, that the acetate form is less expensive than natural tocopherol oils because it is more stable, with a longer shelf-life, but also with substantially(?) reduced bioavailability. Dual Use (talk) 09:14, 9 January 2010 (UTC)

He's talking about the esters of tocopherols with acetic acid, right? What anions are we talking about? :S AFAIK the phenol should be protonated at physiological pH and the hydrogen-bonding would be more significant than any acid-base chemistry. John Riemann Soong (talk) 09:28, 9 January 2010 (UTC)

Shut eye

1. What's the difference between being asleep and being unconscious?

Being asleep is one of the different ways to be unconscious. It is a form of unconsciousness.

2. Is the one state of mind different compared to the other?

I'm not sure, but I remember there were some related answers from imaging working brains (with positron emission tomography?)

3. Is being asleep laying down different to sleepwalking?

Yes, sleepwalking is an altered form of (very impaired) consciousness, not an unconscious state in the medical sense, although it probably is in the legal sense.

4. Are dreams possible when you're unconscious?

Maybe. There is some evidence that people under anesthesia suffer unpleasant dreams, but most of the time they don't remember those.

Thanks, NirocFX (talk) 10:11, 9 January 2010 (UTC)

You're welcome. GandM (talk) 10:39, 9 January 2010 (UTC)

Links added and fixed. ~AH1^(TCU) 17:55, 9 January 2010 (UTC)

I disagree that sleep is necessarily a form of unconsciousness. For example you are quite plainly conscious when dreaming (though not conscious of external stimuli). I can sometimes remember thinking about stuff while asleep, even while not dreaming. (I wouldn't know how to tell you how I knew I was asleep, which I suppose would be your next question. I just knew.) --Trovatore (talk) 21:15, 9 January 2010 (UTC)

How is this possible?

Hi,

Please help me understand how it is possible for us human beings to operate ourselves.

Take for instance a toy action figure or a car, those things have power sources. Where are our power sources? We're all flesh, fat, blood, bones and water basically.

How are we able to move our eyes, hands, legs; go to sleep and wake up when we want to without someone pushing a button? I'm even scared to ask how and where dreams fit in.

Thanks, NirocFX (talk) 10:33, 9 January 2010 (UTC)

1. Our power source can be understand by checking out the metabolism article.

2. We move because our brain sends signals to our muscles, which then use that metabolic energy to get to work.

3. Dreams are best understood in a psychological context. I would direct you to the article on subconscious for an overview, but it is of alarmingly poor quality. Dreams looks a little more up to snuff though it lacks confidence as to what the purpose of dreams are. Oh well. Vranak (talk) 10:52, 9 January 2010 (UTC)

I would dispute that dreams are best understood in a psychological context. The most compelling theories of why we dream and what they do are neurological—they are the brain's way of reorganizing information at the end of the day, and should not be deeply read into for content. Psychological theories of dreaming have led people down a number of paths that have absolutely no scientific rigor to them. --Mr.98 (talk) 15:15, 9 January 2010 (UTC)

This is probably because you don't understand or appreciate psychology. Vranak (talk) 18:52, 9 January 2010 (UTC)

The tricky conceptual point is that we operate ourselves as ourselves. It isn't that human beings are little creatures riding around in a human body—though it can certainly feel that way, especially when we realize, as we all do, how much our body is limited compared to what we would imagine it being able to do in our minds. But the mind is part of the body, a product of the brain, and the entire apparatus is connected quite inextricably.

Our cells generate power from the food that we eat, to put it simply. How they do that involves chemistry, and is complicated, but is definitely known.

In the end, the tough question is how consciousness works—how we are anything more than machines-made-of-guts, if we are. For that, we as of yet have no compelling scientific answer. --Mr.98 (talk) 15:15, 9 January 2010 (UTC)

It is magnetic. It's covered all over in little magnetic twitches and electrical signals. Although your question seems to be "What is my soul?" the most they know is that each movement and probably each thought is accompanied by a little electrical signal like a robot or a computer with wires and resistors. The fuel is sugar and oxygen which is probably well described on the metabolism article. ~ R.T.G 17:24, 9 January 2010 (UTC)

(No, it's not magnetic) SteveBaker (talk) 19:18, 9 January 2010 (UTC)

The oxygen is carried around the blood by iron magnetising with it. That's just part of the fuel but it is one of the amazing little technical things the body does to let you move around the place, carries fuel for burning one atom at a time. You've enough tiny little bits of iron in the blood to make a handful of small nails and without it you'd be some sort of plant. That's why foods are often "fortified with iron". ~ R.T.G 20:52, 9 January 2010 (UTC)

To clarify, humans have abour 3-4 g of iron in their body, of which about 2.5 g is in hemoglobin in the blood. That's about one 2" nail. And the iron isn't "magnetising" with oxygen, but rather forming a coordinate covalent bond. Additionally, while many animals use iron to transport oxygen, there are some, such as octopuses that use a copper based molecule, Hemocyanin. You wouldn't necessarily be a plant if you didn't have iron in your blood; you might just be a squid. Buddy431 (talk) 22:13, 9 January 2010 (UTC)

The nervous system directs the bodily movements, and the heart and brain, among other parts of the body are "co-dependant". As for dreams, I would guess that it is the subconscious brain producing "images" that are experienced by the person's "mind" while the conscious mind is at rest. Dreams often occur during different sleep phases, for example REM sleep rather than deep sleep. ~AH1^(TCU) 17:54, 9 January 2010 (UTC)

The energy to power the human body comes from the food we eat - combined with the oxygen we breathe. Just like a car burns gasoline with oxygen - so we burn carbohydrates and fats. The "burning" is slower and gentler than for a car - but the chemical reactions produce similar results. The sugars are stored in our blood - longer term storage as fats. These are broken down as needed to produce the chemical energy to make muscle fibres contract and body parts move. The controls for all of this is our brains - which are a lot like computers - but immensely more complex. When something in our environment causes us to need to do something, it can either be entirely automatic (such as when your hand jerks away after touching a hot stove) or consciously driven. Signals are passed from brain-cell to brain-cell just like they travel from transistor to transistor in a computer. Eventually, commands to move a muscle travel down nerve fibres to the appropriate place and cause the chemical change that results in sugars being converted to energy to contract or relax a muscle. All of this is fairly easy and well-proven stuff - except for the fact that we feel like we're somehow "in command". It doesn't seem to us like we're all just a bunch of computer software running in a biological computer - even though that is undoubtedly the truth of what's going on. The experience of conscious behavior is hard to explain - and science has a long way to go to pin that part of the explanation down. If we knew that our computers had consciousness - we'd understand what was going on inside our own heads - but we don't. SteveBaker (talk) 19:18, 9 January 2010 (UTC)

Hot spots in cold water

(moved from article space) FOR A WHILE NOW I'VE WONDERED WHY WHEN I SWIM AT A PLACE CALLED DROMANA IN THE SAME BODY OF WATER THERE ARE WARM AND COLD PATCHES ESSENTIALLY COEXISTING. I GUESS MY QUESTION IS HOW IS THIS POSSIBLE WITHOUT IT SEEMS MIXING AND BECOMING A UNIFIED TEMPERATURE?Gazzasifu (talk) 10:50, 9 January 2010 (UTC)

See thermocline for something like this. --76.182.94.172 (talk) 13:39, 9 January 2010 (UTC)

This report (beware 2GB pdf!) gives some figures for thermal stratification at Dromana (assuming that this is the right location), with one example from December (Figure A3.6) showing a decrease of nearly 1.5° from 19.5 to 18 at about 2m depth, I guess you might notice that. Mikenorton (talk) 17:32, 9 January 2010 (UTC)

Also, some ocean currents such as the Gulf Stream can periodically fluctuate and produce warm and cool eddies more than 10C different in temperature less than a few hundred km apart. ~AH1^(TCU) 17:44, 9 January 2010 (UTC)

Data mining, data is doubling every three years

Hi, on Data mining is says on the first sentence "...the amount of data is doubling every three years." The source is locked for subscription. Does someone have access to that source or can someone know offhand what data is doubling every three years? I assume it is about online data but who knows. Happy new year to you. ~ R.T.G 17:08, 9 January 2010 (UTC)

This report (which may be referring to the same thing) talks about "the amount of data storage required" as doubling every three years. Mikenorton (talk) 17:37, 9 January 2010 (UTC)

That would be less than the rate of Moore's law for hard drives - so such a rate of increase may well be just a matter of what businesses and/or government can afford to store for a given price. SteveBaker (talk) 19:06, 9 January 2010 (UTC)

So should I quote dictionary.com and change the article accordingly? I am thinking yes. This is the sort of data that data mining is all about right? ~ R.T.G 20:17, 9 January 2010 (UTC)

You lost me. What does dictionary.com have to do with this? Comet Tuttle (talk) 20:30, 9 January 2010 (UTC)

The ref Mike Norton showed us, encyclopedia.com sorry. ~ R.T.G 20:54, 9 January 2010 (UTC)

About Sinkiang, phillippine sea and Noha’s flood

Hi,

I believe that once the world was struck by a broken star/something in China’s Sinkiang area and then fall into the phillippine sea. This event may be related with the Noha’s flood. Do you know anything about this event?

Regards --Mohsin —Preceding unsigned comment added by MohsinRaz (talk • contribs) 17:47, 9 January 2010 (UTC)

No. Can you tell us what makes you believe that? --TammyMoet (talk) 17:57, 9 January 2010 (UTC)

It struck China's Xinjiang area (North-Western China), then fell into the Phillippine Sea (South West Pacific Ocean)? You mean it bounced and the water from the Pacific Ocean ended up in the Middle East? Where did you get this information from, because it's news to me? --KageTora - (影虎) (Talk?) 18:34, 9 January 2010 (UTC)

(ec) Searching Wikipedia for "Xinjiang meteorite" came up with Fukang (meteorite). Couldn't find anything related to the Philippine Sea (which seems like it would be an awful long way away). When meteors fall into the Earth's atmosphere they're often called "shooting stars" but they aren't actually pieces of stars. Typically they're chunks of rock.

I think any connection to Noah's Ark is going to be purely speculative. Rckrone (talk) 18:41, 9 January 2010 (UTC)

You might be interested to see List of impact craters on Earth and Deluge (prehistoric). China and the Philippines seem to have got off very lightly.--Shantavira|^{feed me} 18:45, 9 January 2010 (UTC)

what's a a broken star/something? Dauto (talk) 18:50, 9 January 2010 (UTC)

I think we can assume it's a meteor or something. It's possible that our OP is not a native English speaker. If "Sinkiang" is really "Xinjiangm" in Urumqi, China (which is what Google-Maps says) - then I think that location is far too far inland (over 2000 miles inland) to have been struck by something that ended up in any ocean. While there may be some truth in that it was struck by a meteor, the details must have somehow been confused or exaggerated along the way. SteveBaker (talk) 19:04, 9 January 2010 (UTC)

Continental drift. Comet Tuttle (talk) 20:28, 9 January 2010 (UTC)

Disrupted food chains

What are some famous examples/consequences of food chains being disrupted i.e. one key species dying out/growing in number dramatically? No points for smartass "humans" answer. Pic related, it's a cane toad.  Skomorokh  19:45, 9 January 2010 (UTC)

Such as when someone introduced a pregnant cat to Stephens Island in New Zealand, which (along with it's kittens) proceeded to quickly wipe out the Stephens Island Wren?

The article on Keystone species gives a few examples. The canonical examples that come to my mind are the reef-building corals (see coral bleaching) and the Easter Island Paschalococos palm. --Dr Dima (talk) 20:07, 9 January 2010 (UTC)

The Dodo of course ~ R.T.G 20:56, 9 January 2010 (UTC)

Lythrum salicaria can destroy the food chain when introduced to wetlands --Digrpat (talk) 21:02, 9 January 2010 (UTC)

Try also Invasive species and related articles ~ R.T.G 21:04, 9 January 2010 (UTC)

Gulf stream collapse & European winter storms of 2009–2010

In this article for The Times, Giles Coren has a bit of a rant about all the "where's global warming now?" remarks that are occurring due to the current weather in the UK. If you don't want to click the link, he basically claims that this weather is due to the Gulf Stream collapsing (which — spookily — was predicted to happen by the Observer just over a month ago). I'd like to know if this is plausible (not that the Gulf Stream will collapse, but that it has collapsed). Although I know next to nothing about climatology, there is no need to dumb down answers if it's a complex matter. --Mark PEA (talk) 20:06, 9 January 2010 (UTC)

I'm no expert, but I live in Norway, which is heavily heated up by the Gulf Stream, and climate would certainly be worse than the slightly heavy winter we've been having over the last weeks if this was the case. I checked ice sheet coverage, and from this image (from this page) it clearly seems that, as usual, there is no sea ice where the Gulf Stream goes. Jørgen (talk) 20:33, 9 January 2010 (UTC)

I live in Ireland. A lot of countries at our latitude are covered in snow most of the year but we usually have snow only in some areas and only for a few weeks. Around 4 or 5 years ago we had two hottest years on record. We always have a few heatwaves but these were full summer and autumn heatwaves and the heat had been increasing for a decade. Then all of a sudden we had the wettest and one of the darkest years on record. Now we are getting -8 degrees at night and snow and frost on the ground even if the sun is shining. But, the record in the last 50 or 60 years is -10 so can't just say it has collapsed yet by that info alone but it did get very hot then very cold. ~ R.T.G 21:12, 9 January 2010 (UTC)

Whilst I find anecdotes interesting, I'm hoping a climate expert can confirm/falsify this hypothesis. --Mark PEA (talk) 22:24, 9 January 2010 (UTC)

If the Gulf Stream had collapsed it would be in all the mainstream news, which it isn't. It isn't even in the article you link to - he says: "I am not saying that the snow we are having now is because of global warming. It is not." He just says this is the kind of weather we can expect if the stream collapses. --Tango (talk) 22:34, 9 January 2010 (UTC)

Structure of guanosine

I stumbled across File:Guanosine.jpg while wasting time with the random image feature, and I noticed that it shows a hydrogen atom that isn't present in File:G chemical structure.png, the image currently used in the guanosine article. I don't know much about chemistry; is there an error in one of the diagrams? (Perhaps this is what the discussion at Talk:Guanosine is about.) —Bkell (talk) 21:09, 9 January 2010 (UTC)

Yes this File:Guanosine.jpg is incorrect, you will also notice a Nitrogen atom with a valence of 4. instead of 3. COnfiemed with one of my biochemistry text books. Graeme Bartlett (talk) 22:22, 9 January 2010 (UTC)

Solar exploration

Will it ever be possible to send a craft to explore the inner workings of Uranus? IF so, could there be a black hole lurking beneath the gaseous emanations?