Wikipedia:Reference desk/Archives/Science/2008 September 27

= September 27 =

Where does my power come from?
I know it comes from a power plant. I live in West Virginia, US. We have a coal fired power plant less than 50 miles from where I live. Someone told me that the energy produced there is sent the the western US and we get our power from somewhere else. Is there anyway to figure out what specific power plant provides the energy for my area? —Preceding unsigned comment added by 96.240.72.130 (talk) 01:35, 27 September 2008 (UTC)


 * See Electric power transmission. As I understand it, the power generated at your local station is put into "the grid," which can be seen as a collective pool that consumers draw power from.  So you don't actually get power from any particular power plant.  It's possible that the electricity produced at your coal plant is being sold to cities in the West, and that your town is buying power from some other source, but that doesn't mean these plants are literally shipping their electricity to the buyers.  It's all just going onto the grid.  --Allen (talk) 03:09, 27 September 2008 (UTC)
 * And looking at the US grid map, WV is all in the East Central region of the Eastern Interconnect, so it is indeed the same grid. It is quite possible that the wires coming from the coal plant run in a westerly direction, but it seems unlikely that the power is being marketed into the Western Interconnect. Franamax (talk) 16:11, 27 September 2008 (UTC)


 * The power systems analyze flows on the grid by instruments located at substations, generating stations and on trnsmission lines. The amount flowing from each source and to each load varies depending on contidions. Computer modelling can determine the effect of adding more or less power to the system at any one node. If the effect of turning your local power plant on or off were compared to the flow to a load in the western US, I expect that lettle effect would be seen, In other words, it would be more likely that your local plant is not literally supplying western load. For one thing, there would be considerable losses of power along the way due to resistance. Edison (talk) 20:04, 27 September 2008 (UTC)

would a free falling object hit with the same force from 40' vs. 20'
my sons cubs scouts is having a experiment with an egg wrapped in a package. it will be dropped from 40' to see if it breaks. My egg was ok at 20' but i have no way of testing it from 40'. I was just wondering if it would hit with the same force at 20' as it would 40'209.244.187.94 (talk) 04:17, 27 September 2008 (UTC) Thank you Ray B.


 * Depends on the package. See Terminal velocity.  If the package has a design that maximizes air resistance (like a parachute, for example), then it might hit with the same force at 20' or 40'.  Otherwise, it will hit with more force.  You might try testing by standing at 20' and throwing the package downward, trying to make it leave your hand at roughly the same speed it hits the ground at when dropped from 20'.  --Allen (talk) 04:26, 27 September 2008 (UTC)


 * Just throw the egg up 20' from where you were standing before and let it fall from there. — DanielLC 16:21, 27 September 2008 (UTC)


 * That would have no effective difference from droping it at 20'. If the egg is at the top of the throw at 20', it is at zero velocity.  From there, the downward flights are identical.  The idea behind the egg drop is to make something that will reach a relatively slow terminal velocity as soon as possible.  Thus, if it hits that terminal velocity at 15', it will drop at that same speed whether you drop it at 20', 50', or 1000'.  That's the idea behind terminal velocity.  --Jayron32. talk . contribs  20:40, 27 September 2008 (UTC)
 * I think you misunderstand. I believe DanielLC's plan was to stand 20' above the ground and then throw the egg 20' in the air, so it is momentarily at rest 40' above the ground, so it will follow the same path as if it were dropped from 40'. --Tango (talk) 20:51, 27 September 2008 (UTC)

Sounds like a cool experiment. What sort of package did you and your kid design?  Plasticup  T / C  05:05, 28 September 2008 (UTC)


 * The pedantic answer is that terminal velocity is asymptotic. So the egg will not ever hit at exactly the same force.--Fangz (talk) 12:53, 28 September 2008 (UTC)
 * I think random fluctuations probably have more of an effect than it not having quite reached terminal velocity. --Tango (talk) 20:57, 28 September 2008 (UTC)

Penrose Diagram
I have no idea how to interpret this. Could someone please help me out? Also, what is a "lightlike infinity"? Ζρς ι'β' ¡hábleme! 05:57, 27 September 2008 (UTC)


 * I resized the image, hope you don't mind. It was a bit... overwhelming before. Anyway, this diagram just shows ordinary flat spacetime in an unusual coordinate system given by tan (u±v) = x±t, or more explicitly by
 * u = (tan−1 (t+x) − tan−1 (t−x)) / 2
 * v = (tan−1 (t+x) + tan−1 (t−x)) / 2
 * The axes marked "space" and "time" are actually u and v respectively. This coordinate transformation maps the whole of spacetime into the diamond. The roughly horizontal and vertical curves are curves of constant t and x. Lines of constant x±t map to lines of constant u±v, so light still travels along 45° diagonal lines in this diagram. Its most useful property is that worldlines which diverge to infinity in the usual coordinates converge to the boundary of the diamond in (u,v) coordinates, so this diagram shows you the mathematical structure of spacetime at infinity. Timelike geodesics extend from the bottom point of the diamond (called "past timelike infinity") to the point marked "timelike infinity" (normally "future timelike infinity"). Lightlike/null worldlines extend from past to future lightlike/null infinity (lower and upper edges of the diamond). You can extend this to n+1 dimensions by using polar coordinates and transforming (t,r) as above while leaving the angles alone. The diamond generalizes to two (hyper)cones with apexes at past and future timelike infinity (which are still points) and glued together at spacelike infinity (which is a (hyper)sphere) . (edit to add: Sorry, I think that's wrong; that mapping isn't conformal. The correct generalization, if I'm not still confused, is to imagine wrapping the diamond around a cylinder so that the left and right vertices (spatial infinity) coincide, roughly as shown here, and then generalize that to a higher-dimensional cylinder Sn × R. Spatial infinity is a point, not a hypersphere.) -- BenRG (talk) 12:00, 27 September 2008 (UTC)


 * That sounds good. They're like those Escher Circle Limit pictures but putting the whole of a 2D space-time in a small diagram. I must admit I always though Penrose diagrams was the name of a much more useful thing which in wiki is called Penrose graphical notation. Dmcq (talk) 12:11, 27 September 2008 (UTC)
 * Yes, Escher's Circle Limit pictures are based on the Poincaré disk model of hyperbolic space, which is a very similar idea. Also very similar is the Riemann sphere. They're all conformal maps. -- BenRG (talk) 15:16, 27 September 2008 (UTC)

Changes in mental processes due to multitasking
I posted this a couple of days ago on the Misc desk as sex differences in internet use and it was suggested I post here. I rewrite slightly:

It is a commonplace observation that women are able to multitask and men cannot. (I should clarify that "multitasking" can involve more than paying attention to electronic information. A sympathetic female journalist was commenting on the recent resignation of Ruth Kelly from the British Cabinet, "to spend more time with her family".  The journalist said that once she had interviewed Kelly by phone, and after a few minutes had figured out -- and the politician had admitted -- that the splashing sounds in the background were of the two year old being bathed.  Good thing the phone didn't drop in the water.)

It is a commonplace observation that those individuals most immersed in computers and the internet are male. Obviously these are both generalisations. One social change commented upon over the last ten years or so is the impact of prolonged and submersive internet use on our thinking and interaction patterns. (See for example the recent Financial Times anecdotal article and interviews here.) One theme is that our attention is being fractured; some observers see this as wholy negative, while others see more positive possibilities.

So we have two conflicting ideas: that the so-called male brain can only cope with one information stream at a time, and that many men and boys thrive in an atmosphere of information bombardment (multiple screens on computers, phones, TVs simultaneously). My question is, is there any serious research on this? And how are these conflicting tendencies reconciled? BrainyBabe (talk) 12:14, 27 September 2008 (UTC)


 * Whatever about commonplace observance the latest statistics as best as such things can be done for this say that more women than men use the internet and use it if anything a bit longer. Just google on 'percenage male female internet usage' and look for 2007 or later. As to multitasking it is something to be avoided if possible even for simple tasks with little overlap if you want to do them properly. Anybody driving round talking on their mobile is a menace. Dmcq (talk) 13:02, 27 September 2008 (UTC)
 * Or driving around while fixing their makeup. :) Zain Ebrahim (talk) 13:04, 27 September 2008 (UTC)
 * Yes, I think it's the assumption that multitasking is an amazing skill that is the problem with the whole thing. People assume that being able to do 5 things at once means you get 5 times as many thing done (and done just as well). You don't. Totally my own opinion here, but I suspect an evolutionary reasoning for the multitasking/singletasking divide. Men were hunters. Attempting to hunt a wild animal while also reading the paper=dead. Remaining focused on the task without distraction=alive. Fribbler (talk) 13:48, 27 September 2008 (UTC)

Thank you for your opinions, but can anyone point me to any research on the subjects under discussion? BrainyBabe (talk) 13:53, 27 September 2008 (UTC)


 * Hmm, this ones a bit old (2001) and relates to multitasking, but not the internet etc. From the American Psychological Association: . And heres another paper, this time on gender differences and multitasking: Fribbler (talk) 13:58, 27 September 2008 (UTC)


 * I'm still not convinced that Media multitasking is always the same as Human multitasking. Your question assumes so, right? For example, I'm currently doing several things that put me into an "atmosphere of information bombardment" but at this moment, I'm fully focused on typing this post. This is not the same as driving while talking on a phone. Zain Ebrahim (talk) 14:28, 27 September 2008 (UTC)


 * I've read the research articles (thanks Fribbler) and they seem to find no significant gender difference. I take the point about different sorts of multitasking; looking after children, in particular, has throughout history been combined with other activities.  And boring or silent tasks may well be enhanced by another "information stream" -- like oganised reading aloud to monks and nuns at refectory, or  those early communists in quiet factories. But these modern shifts in patterns of attention -- the inability to settle down with a book, for example -- and at another level the very existence of the vulgar dismissive phrase TLDR -- these are subjects under discussion, anecdotally, as I said.  I suppose it will all come out in the wash (as long as the Blackbery didn't get inadvetently left in the pocket). BrainyBabe (talk) 16:42, 28 September 2008 (UTC)

an idle speculation about songbirds


Thinking about the raucous squawks of rosellas and peacocks, I suddenly wondered if there's a general rule there: Do beautiful birds have ugly calls and vice versa?

Adambrowne666 (talk) 12:52, 27 September 2008 (UTC)


 * You're probably right in general. If the girl is attracted by one thing why invest much trouble in anything else? That's all evolution will do? Dmcq (talk) 13:05, 27 September 2008 (UTC)


 * Presumably all birds find some members of their own species attractive. As for what humans find beautiful, most people don't find crows particularly handsome (although I do), and most people would not describe the crow's call as beautiful.  I don't know what sound a Marabou stork makes, but I find it hard to imagine it twittering mellifluously.  --Sean 15:26, 27 September 2008 (UTC)


 * As a general rule (AFAIK) - small birds sing, larger birds squawk. --Kurt Shaped Box (talk) 16:44, 27 September 2008 (UTC)


 * Small birds tend to have to hide. Big birds can strut around and be butch, they don't have to sing to get a mate. As to the maribou stork mom thinking its chick is pretty, whilst we're being anthropomorphic perhaps it thinks that's my boy, no nancies in this nest, you'll beat up the neighours in any fight. Dmcq (talk) 23:31, 27 September 2008 (UTC)
 * Different birds cue into different things in song depending on the species. Lady prions are able to assess the quality of a male through the call. In smaller songbirds, which have more complex syrnixes, it is song complexity a dn melody that females like, which is why we like them too, but in other species, like bitterns or Kakapos, it is volume or depth. The srceaches of parrots are not mating calls but contact calls to keep in touch with others of the species by the way, and the contact calls (as opposed to mating calls) of songbirds are simpler and less beautiful even in great singers. Sabine's Sunbird  talk  22:17, 28 September 2008 (UTC)


 * Fair point, SS - but even the mating calls of parrots are (in every species I've ever heard - aside from the Budgerigar, which is melodic in a twittery way) still loud, harsh and screechy/squawky, albeit less so than the ear-splitting contact calls. --Kurt Shaped Box (talk) 22:37, 28 September 2008 (UTC)

Thanks, all; I should have guessed it wouldn't be so simple. I'm with you, Toto, I find crows handsome too - their feathers make me think of a phrase used by Lord Dunsany to describe one of his pirates: 'bright black'. Adambrowne666 (talk) 02:27, 30 September 2008 (UTC)

Uranium nitrate in medicine?
My father went to a homeopath and he prescribed my father a liquid medicine(I presume it is a solution) which had the label "uranium nitrate" on it. Could it be this? Is this compound used in medicine? How risky could it be?Leif edling (talk) 15:19, 27 September 2008 (UTC)
 * From homeopathy:
 * Common homeopathic preparations are diluted beyond the point where there is any likelihood that molecules from the original solution are present in the final product; the claim that these treatments still have any pharmacological effect is thus scientifically implausible
 * The stuff is probably just water, but on the other hand, why drink water from a quack with a uranium supply? --Sean 15:29, 27 September 2008 (UTC)

You might not have realized this but homeopathy is a popular method of treatment here in India. So is homeopathy totally pseudoscience?Leif edling (talk) 17:21, 27 September 2008 (UTC)
 * Yes. The proposed mechanisms are pure bunk. Homeopathy may have some successes via the placebo effect, or simply by providing generally useful suggestions (go for a walk, drink more fluids, prefer natural to processed foods...), but drinking expensive labeled water with no substance in it is no different from drinking plain water with no substance in it. --Stephan Schulz (talk) 17:38, 27 September 2008 (UTC)
 * Additionally, I doubt they would be able to treat your father with uranyl nitrate, it's highly toxic, is a hidious onslaught to your kidneys and is likely to be highly regulated, despite the "dilution" that the above quote states. Stick to real, evidence-based medicine, in my opinion. —Cyclonenim (talk · contribs · email) 17:40, 27 September 2008 (UTC)
 * If it's homeopathetic then it is statistically highly unlikely to be even one molecule of the "active" ingredient in the treatment...so it's not going to harm you - it's just not going to do you any good either. That's why they can sell the stuff without going through FDA trials, proving efficacy, etc.  What you have there is a $100 bottle of water. SteveBaker (talk) 22:03, 27 September 2008 (UTC)

Perhaps we can put it this way. If it is not diluted to the point of being just water, it is potentially toxic. If it is diluted to the point of being just water, it's just water. --98.217.8.46 (talk) 18:21, 27 September 2008 (UTC)
 * I think the point is though that it seems unlikely that any old quack could get ahold of uranyl nitrate. Given this, it seems likely that the quack is a worse quack then your average quack because the quack didn't even follow the rules of quacks Nil Einne (talk) 19:00, 27 September 2008 (UTC)


 * The doc test: If it looks like a quack, swims like a quack and ducks like a quack, then it probably isn´t a doc.  --Cookatoo.ergo.ZooM (talk) 19:47, 27 September 2008 (UTC)

Some homeopathic remedies are not completely diluted. But if any of those are actually helpful, it's by pure freakish chance, and not because the homeopaths have any idea what they're doing. Someguy1221 (talk) 22:47, 27 September 2008 (UTC)


 * I agree with the general condemnation of homeopathy, but the logic that all poisons are bad is guilty of the same non-scientific over-simplification of which you accuse homeopaths. My mom started her first round of chemotherapy on Friday.  Plasticup  T / C  05:12, 28 September 2008 (UTC)


 * Well, I'm sorry to hear about your mother. I hope she does well. But I don't see where anyone here was arguing at all that all poisons lack medical usage. There is a big difference between saying that homeopathic dilutions are worthless and saying that all "poisons" are medically useless. --98.217.8.46 (talk) 05:27, 28 September 2008 (UTC)


 * While you and your mum have my sympathies and I hope it goes well for her, I would say chemotherapy does actually exemplify the point. There's no doubt all chemotherapies are bad for the human body. The only reason we use them is because cancer is often worse and if used effectively, chemotherapy can help to kill the cancerous cells without killing the person who has cancer. In other words, you need a pretty extreme case where administring such a highly toxic compound as uraynl nitrate is worth it unless the uranyl is so dilute to be mostly worthless. Nil Einne (talk) 17:23, 28 September 2008 (UTC)


 * My sympathies as well. Alas, I know nothing about the uranium nitrate the original poster asked about. I agree with Plasticup (and apparently disagree with 98.217.8.46) that "all poisons are bad ... [until] diluted to the point of being just water" is not always true. Perhaps a better example of an exception is hypervitaminosis A and oxygen toxicity -- while overdosing on Vitamin A or oxygen is bad, a deficiency of Vitamin A or oxygen is also bad. --68.0.124.33 (talk) 02:28, 2 October 2008 (UTC)

hydrogen storage
im trying to find out if i can store hydrogen with low psi for intake injection on my scooter? because i can produce it in house easier. the model h2 toy rocket kit holds at 3 psi before ingnition. would a small compress still heat it to much? could a modifacation be made to the toy rocket generator? —Preceding unsigned comment added by Fearlss69 (talk • contribs) 18:03, 27 September 2008 (UTC)
 * If you have a gasoline-powered scooter, it is not advised that you use other fuels, such as hydrogen gas, to operate it. In the first case, the engine will not run very efficiently, if at all.  Secondly, gases, like hydrogen, make poor fuels for internal combustion engines.  Hydrogen power is FAR more effective and useful in chemical/electrical engines powered by fuel cells.  Hydrogen gas works fine for a single ignition rocket engine, which is basically a single controlled burn.  For a gasoline-powered internal combustion engine, which depends on carefully timed repeated explosions, changing to a different fuel will mess with that timing, again, if it works at all.  If you are asking if it would be a good idea to strap a hydrogen-powered rocket to your scooter, well, via con dios and have a friend with a cell phone who can dial emergency services when you need it.  --Jayron32. talk . contribs  20:22, 27 September 2008 (UTC)
 * Also, you might just fry your engine due to hydrogen embrittlement. --Stephan Schulz (talk) 20:32, 27 September 2008 (UTC)


 * The problem is that if you store raw hydrogen gas at low pressure, you won't have enough of the stuff to go very far. You need to compress the heck out of it to get enough into your tank to be worthwhile.  The answer for storing hydrogen is to store it in the form of metal hydrides and react it in a fuel cell to make electricity.  Internal combustion simply isn't a smart way to deal with the difficulties of hydrogen.  There are other gasses (propane is certainly one) that internal combustion engines handle rather well - but you still need a high pressure feed. SteveBaker (talk) 21:57, 27 September 2008 (UTC)


 * The problem with propane is that our atmosphere doesn't seem to like it.  Plasticup  T / C  05:14, 28 September 2008 (UTC)


 * Yep - indeed. But the amount of atmosphere you can make happy by converting an already rather efficient mode of transport to run on hydrogen is pretty limited...and the effort involved with production of said hydrogen in the world as it is today is pretty much guaranteed to cause greater amounts of atmospheric unhappiness than leaving well alone! SteveBaker (talk) 02:42, 29 September 2008 (UTC)

Recipe for Life
Hydrogen + Ammonia + Methane + Water + Source of Energy + 4 Billion Years = Me!

Is this more or less correct? Sappysap (talk) 18:35, 27 September 2008 (UTC)


 * Well you left out a few molecules. See Abiogenesis. --98.217.8.46 (talk) 19:53, 27 September 2008 (UTC)


 * You should probably include free oxygen - and stipulate 'liquid' water. There are also a bunch of things you should probably specifically exclude (high acidity environment), etc. SteveBaker (talk) 21:52, 27 September 2008 (UTC)


 * Electronic Arts + Spore (game) + a few hours = Me!  Plasticup  T / C  05:16, 28 September 2008 (UTC)


 * I don't think this is very correct. Me is more than just base chemicals - you need billions of years of selectional pressures and environmental factors to get humans. Otherwise, well, you might as well say neutrons + protons + electrons + billions of years = Me.--Fangz (talk) 12:51, 28 September 2008 (UTC)


 * 23/3 (I should probably offer a prize to the first person to correctly explain this answer) SteveBaker (talk) 02:39, 29 September 2008 (UTC)
 * You owe me a beer. DMacks (talk) 04:54, 29 September 2008 (UTC)
 * Oooh! You're good!  I do indeed owe you a beer...I thought I was going to be safe - but no.  Anyway - "Conway's Game of Life" is a computer "game" (well, "Mathematical Recreation" might be a better term) in which things that seem somewhat like life are simulated in the computer.  There are actually a whole family of games that use different variations on the rules that Conway wrote.  Some of these variations are boring - others are more interesting than the original game.  The rules for these myriad variations are encapsulated in just a pair of numbers which is the "recipe" for the game.  The recipe for life is therefore 23/3. SteveBaker (talk) 19:18, 29 September 2008 (UTC)

Plant species
Could someone help me identify this small plant species? Grows on sandy dunes by the sea. Picture was taken in the summer, in southern Portugal. Very common there. Thanks. Hús ö  nd  21:01, 27 September 2008 (UTC)


 * Well, it looks like a succulent, so I will guess it belongs to the Crassulaceae. Although without flowers, I can't really tell for sure what family it belongs to. It grows more like a Sedum than anything else, so it might be Sedum sediforme .--Eriastrum (talk) 17:25, 28 September 2008 (UTC)


 * Hmm, nope, definitely not the species on the flickr photo. The plants growing on the background of the picture I provided are the same as the one being closed up. It is clear that they're not the same kind as the one appearing on flickr. Yet, they do appear to be Sedum. Hús  ö  nd  18:41, 28 September 2008 (UTC)
 * Does sea spurge, Euphorbia paralias, seem a possibility (photos here and elsewhere on the Web if you Google for "sea spurge")? Deor (talk) 16:06, 29 September 2008 (UTC)
 * The more I poke around, the more convinced I become that E. paralias is what it is. Compare your photo with this one, for instance. The plant is native to the Mediterranean region, though it seems to have been spread widely to other areas, where it's often regarded, I gather, as an invasive pest. Deor (talk) 22:20, 29 September 2008 (UTC)


 * Yes!!! It's definitely E. paralias! Thank you so much for your help, Deor. :-) Hús  ö  nd  18:53, 1 October 2008 (UTC)