Wikipedia:Reference desk/Science

Wikipedia:Reference desk/headercfg

May 8

Latest vaccines

How exactly does O157 work and what is polysaccharide? —The preceding unsigned comment was added by Sharvanir (talk • contribs) 05:28, 8 May 2007 (UTC).

Do you want to know how the vaccine works or how Escherichia coli O157:H7 works? A polysaccharide is a macromolecule constructed as a chain of sugar monomers. If you want to know how E-coli "works" look at the link I provided. A vaccine for it would work as most all vaccines do, artificially stimulating an immune response to an antigen naturally present on E-coli, resulting in the human body producing antibodies for it (as well as the various white blood cells that respond specifically to that antigen). This all results in resistance to the actual bacteria if you're infected, as the body responds more swiftly and more strongly to bugs it has seen before (or thinks it has seen, at least). I'm not sure what the exact mode of action is for the proposed O157 vaccines. For more information look at Immune system#Immunological memory, as well as Immunity (medical) for a thorough look at it. Someguy1221 05:52, 8 May 2007 (UTC)

Oh, and as for any possible connection between the two items you asked about, the antigen the body develops an immune response to is often a polysaccharide, or more specifically an oligosaccharide, although I don't know if that's the case with O157 or any of its proposed vaccines. Someguy1221 06:05, 8 May 2007 (UTC)

Need help with a citation regarding fitness

I'm looking for something to back up a stat I read in a running magazine about 10 years ago: that the optimal VO2 max improvements happen after 35 minutes of target rate exercise. I don't know if I'm just searching with the wrong search terms; the Wikipedia Google Queen needs a fair knight to rescue her. Thanks in advance. Anchoress 06:22, 8 May 2007 (UTC)

Did you see Training effect? I always thought that the greatest improvement came when the system was just at the edge of anaerobic excercise. I think it might take 35 minutes of typical excercise (i.e. 75% of capacity) to reach the anaerobic threshold but I htink that would vary by individual? Lance Armstrong isn't going to improve Vo2 max with just 35 minutes of excercise. Just a guess though. Might want to search "anaerobic VO2" for extra hits. Also, check on how long glycogen remains in the blood stream. it can provide oxygen for metabolism. it's lifetime in the blood may change how effective excecise is. again, this is a subjective guess. --Tbeatty 06:42, 8 May 2007 (UTC)

"glycogen vo2max" http://www.coolrunning.com/major/97/training/hampson.html not sure it has everything you need. --Tbeatty 06:48, 8 May 2007 (UTC)

Yeah thanks a lot, but I'm really not looking for anything that complex and subtle. For my current purpose (although the link you provided was very interesting and your other points were good too), I'm not going to be getting into anaerobic thresholds or glycogen; I'm really just interested in that particular point, if it exists somewhere on the web. It doesn't need to be a complex stat, and it doesn't have to relate to running. And this is for recreational fitness, absolutely not for hardcore competitive training stuff. But I DO appreciate the info and the links, tho. Anchoress 07:11, 8 May 2007 (UTC)

Iron (III) iodide

Why doen't thuis species exist together with iron (III) carbonate? Are there any other reasons except for steric hindrance?Bastard Soap 11:12, 8 May 2007 (UTC)

The ferric ion oxidises the iodide to iodine so that you end up with FeI₂ and I₂. It would not be due to steric hindrance. For ferric carbonate, carbon dioxide would be given off. GB 11:37, 8 May 2007 (UTC)

Redoxreactions happen if you combine Fe(III) which has the potential to oxidize other compounds with iodide wich has the potential to reduce other compounds. If you look at the redox potential you get out that a reaction is possible and exothermic and therfore it starts. The carbonate is a problem of Mass action law. The carbonate is in equilibrium with carbon dioxide over carbonic acid and if the equilibrium is shifted towards the acid the carbondioxide gets lost and you end up with a iron hydroxy carbonate.Stone 14:35, 8 May 2007 (UTC)

So for the carbonate it's something like this: [Fe(H20)6]3+ CO3 ----> [Fe(H2O)5(OH)] O + CO2 It's an acid base reaction not a redox right?Bastard Soap 15:35, 8 May 2007 (UTC)

• Carbonate is CO₃^2-, and needs to combine with 2 H⁺ in order to become carbonic-acid/carbon-dioxide. If you use H₂O as the source of H⁺, you get OH^- as a byproduct. Carbonate (or indeed any base) in water generates hydroxide. DMacks 18:28, 8 May 2007 (UTC)

Equations For A Gas Undergoing Adiabatic Process As it Obeys Van Der Waals Equation

I saw about the equations for an ideal fluid(or gas) undergoing an adiabatic process viz p(v ^g)=constant , T(V^(g-1)) =constant and T(P^(1-g)/g)= constant where g=specific heat for constant pressure/specific heat for constant volume.ref:[[1]]. I also saw about the derivation of van der waals equation ref: [[2]] According to which the van der Waals equation was devised based on a modification of the ideal gas law. The equation approximates the behavior of real fluids, taking into account the nonzero size of molecules and the attraction between them. The van der waals equation is $(p+a/v^{2})(v-b)=kT$. Are there equations for gas(or fluid) undergoing an adiabatic process if this van der waals more exact equation is taken into account? How to derive and solve them?. I searched web pages and didn't find any. Thank you 121.247.80.107 12:09, 8 May 2007 (UTC)

See van der Waals equation#Other thermodynamic parameters. Adiabatic process of the kind you are looking for is the process in which S=const and N=const. It is referred to, speaking more strictly, as an isentropic process with a fixed number of particles. Hope this helps. Dr_Dima.

What The Bleep Do We Know?

In the film What The Bleep Do We Know?, is it true that nothing touches another? What is your opinion of Masaru Emoto theory? Do our thoughts travel forever? If it does, please explain in layman's terms what that means......—The preceding unsigned comment was added by Juliet5935 (talk • contribs) 13:02, 8 May 2007 (UTC).

What the bleep?think that whole touching thing has to do with the atoms electrons and stuff Maverick423 Says Im in ur science steeling ur gravities 13:42, 8 May 2007 (UTC)

There's an article on What the Bleep Do We Know!? in Wiki, in case you wondered. Dr_Dima.

Let's take these one at a time:

1. Things touching: Well, at the level of atoms - the idea of 'touching' is a bit vague. The atom has a teeny-tiny neucleus and almost all of its "size" comes from a cloud of electrons - which themselves are not hard little points but fuzzy probability clouds. When two surfaces come close - the atoms start to repel each other - and this repulsive force is what stops the electron clouds of the atoms from overlapping. So in a sense, yes, nothing really touches anything else - but in another sense, the whole meaning of the word "touch" is kinda meaningless in a world where everything is made of fuzzy probability clouds.
2. Masaru Emoto: Nut job. A very simple double-blind experiment would certainly prove him wrong.
3. Do thoughts travel forever? Well, a thought is a series of electromagnetic pulses going through your neurons - electromagnetic waves travel outwards as photons - and whilst most of them are absorbed by your skull, skin, etc - some will probably shoot outwards into space...I guess some very tiny part of our brain waves travel "forever". But I'm sure that's not what was being suggested wherever you read that...asking: Does the impact of our thoughts last forever? Perhaps that's closer to the true issue here - and again the answer is a very cautious "Yes" - chaos theory says that a butterfly flapping it's wings in China can cause a Tornado in Texas 10 years later, everything is tangled up with everything else and the effect of a single thought is just as likely to cause some nearly random macroscopic event to happen a million years from now. But lest we get too self-important - the future effect of a small, irrelevent, unexpressed thought is likely to have a similar impact to shedding a skin cell and a vastly smaller effect compared to taking a really good shit. Let's not get too existentialist about these simple physical processes!

SteveBaker 13:49, 8 May 2007 (UTC)

Something it seems like some people just can't get over is that human thought, nor emotion directly affects reality. Only our physical actions can change the reality we know around us. This is what physics is about. To respond to SteveBaker's comments, I second him on 1 and 2. On 3, wave and field interference would pretty much eliminate any electromagnetic wave produced by, for instance, a synapse. As for taking a really good shit, well, I love how informal we are on the Desk here :) [Mac Δαvιs] ❖ 16:36, 8 May 2007 (UTC)

masaru emoto claims that ice crystals change shape if you are nice to them. But how do they know what is nice? And wouldn't it be much easier to just force them into nice patterns?

Indeed. It would be so easy to double-blind that experiment, and yet I can find no mention of a double-blind experiment that shows this result. For all the horrendous science though, the moment I actually walked out of the cinema was when they seemed to be suggesting that the woman could choose not to be deaf. Hey! It's all your fault! O_o Skittle 18:52, 8 May 2007 (UTC)

More than that - James Randi has offered the guy a cool million dollars if he can demonstrate this emotional water effect in a double-blind experiment. Surely he would not turn down such a deal if he was even remotely likely to pass it. SteveBaker 22:38, 8 May 2007 (UTC)

On the "touch" point, this is just another example of intuitive spatial metaphors not applying well at the atomic much less subatomic levels. If you had a rigorous definition of "touch" then yes, things touch. If you use an unrigorous definition then no, they don't, but all that really does is show why you need to be careful in defining such things if you want a common term to have meaning in a scientific context. --140.247.240.101 19:38, 8 May 2007 (UTC)

Exactly - but as is so often the case, this is just a problem of language and human perceptions - the underlying science is quite clear. SteveBaker 22:38, 8 May 2007 (UTC)

Emoto is not the nut job, JZ_Knight is the nut job! Vespine 23:03, 8 May 2007 (UTC)

Emoto is the nut job: "we have been wasting and ignoring [water]. If I was water, I think I would be mad too". Not the words of a scientist. Aaadddaaammm 02:28, 9 May 2007 (UTC)

I was part of a Jeung San Do meditation group (yes, chanting) a few years back. Its a very intriguing experience, and yes, even enlightening. I can't say I did it for the precise spiritual reasons that the chant leaders would have wanted for me, but I did it because I did perceive to get some benefit and clarity of mind. It's interesting all the thought experiments you can do while chanting!

I do seem to remember all kinds of odd beliefs that made little sense if analyzed from what I would consider to be a scientific viewpoint, accounting for all known forces, properties of objects, etc. One of the beliefs was that chanting could change physical characteristics of water, ice, or crystalline structures. (Of course, certain sounds may have some sort of effect if you hit an object's resonant frequency, but the belief system went far beyond that.) ... Hmmm... upon my first glance at Masaru Emoto, they may have in fact been showing his particular book. But, fact is, they ABSOLUTELY believed it, like there was little questioning of it, which I found a touch worrisome.

In terms of consistency, though, I think I can see why. They used chanting to cure all kinds of ailments, specific chants for specific things. I never questioned, knowing they had a particular faith in it. Chanting does something to the body, its a bit of a workout actually, so I could see that, say you had a headache, and you chanted for 20 minutes, your blood may become more oxygenated or somesuch, and the headache may "go away" because its become much less of a nuisance, or the possibly physical aspect that caused the pain has been nullified. Actively singing for a choir for 20-30 minutes may possibly do the same thing.

But the chant leaders, who where Korean, always seemed to extrapolate their beliefs much like, ah, its hard to describe. Imagine a world where the Scientific Method is not taught or has not been ingrained into people's minds. They don't question it because they don't know how or why. I didn't read the book. I wasn't really in the mood to read something my mind would quash as utter nonsense, so I don't know if he wrote the book as a quack would sell an elixir or if he actually believed it.

It might be right to call Masaru Emoto a nut job, but there seems to be a lot of people ready and willing to accept the nuttiness.

(random thoughts by Root⁴(one) 04:20, 9 May 2007 (UTC))

Can Stars in Foreign Galaxies Be Seen?

I read somewhere a long time ago that it was not possible to resolve individual stars located in galaxies other than the Milky Way (except in some cases when a star goes supernova). It is still the case today?--JLdesAlpins 15:50, 8 May 2007 (UTC)

No it is not the case today. In fact, it is not the case since at least 1925, see Andromeda Galaxy. Cheers, Dr_Dima.

Indeed, Looking at the galaxy article, it seems that Edwin Hubble was the first to resolve individual stars in a galaxy. Though Immanuel Kant had guessed that galaxies (then called nebulae) were groups of stars in the 1700s. -- Diletante 16:27, 8 May 2007 (UTC)

Are we mostly seeing stars in other galaxies?

When we look at a foreign galaxy, are we mostly seeing stars, or dust, or what? Thanks. --TotoBaggins 17:59, 8 May 2007 (UTC)

Could you please elaborate your question? We only see that which emits light. Dustclouds aren't as abundant in space as clouds of hydrogen, helium and whatnot in nebulae (where stars may be born). Still, these absorb light a lot, so the vast amount of what we see are stars. I have a feeling this doesn't quite answer your question. :) 81.93.102.185 18:49, 8 May 2007 (UTC)

Galaxy#Multi-wavelength observation and Dark matter shed some light, if I may use that expression. -- Diletante

Generally, when you look at the night sky, almost everything you see are stars in our own galaxy. If you know what to look for, you might make out the smudge of a distant galaxy, Andromeda if you are in the north and LMC and SMC if you are in the south, but you need a decent dark sky to see them with the naked eye. The faint glow that you see there is the combined light of all the stars in that galaxy. Vespine 23:00, 8 May 2007 (UTC)

OK, thanks to you both. I guess I had always assumed that the bright bits of galaxies were all stars, but then had read that dust could be heated up by various gravitational actions, and then you have nifty things like accretion disks and relativistic jets, and so on, and I was less sure that the diffuse bright areas in galaxies were all stars. Thanks for the answers. The whole business never ceases to astound me; it's just mind-boggling how big it is. --TotoBaggins 01:16, 9 May 2007 (UTC)

If you need any more evidence of that have a peek at Ultra Deep Field, if you haven't seen it already. This blew my mind completely. Vespine 04:45, 10 May 2007 (UTC)

Glass heating

Durring chemistry I was heating something in a test tube and after a while the blue bunsen flame turns yellowish and returns blue when you remove the test tube. Any body know why it does this?Bastard Soap 18:14, 8 May 2007 (UTC)

Perhaps you have effectively performed a flame test and proven that your test tube is made out of Soda-lime glass. DMacks 18:22, 8 May 2007 (UTC)

See Flame. It could also be the test tube interfering with the available oxygen flow and creating soot particles. --Tbeatty 06:36, 9 May 2007 (UTC)

Tbeatty I think that's highly improbable, I wasn't blocking the bunsen burner hole besides it should take the necessary air from the air hole not from the hole of the flame.Bastard Soap 12:58, 9 May 2007 (UTC)

Isn't the entire visible flame the location where combustion takes place? Therefore, if you place the tube in the flame, you disrupt the mixture and create soot. Soot is what makes it yellow. You only have to create a small amount of incompletely burned gas. I think you can force a pot to do the same thing on a gas stove. --Tbeatty 13:27, 9 May 2007 (UTC)

One interesting clue is that the color only appears "after a while" (thanks for being a bery careful observer, BS!). I would think that causing incomplete combustion would be more likely when the object is cool, i.e., right away, and become less of a factor as it got up to flame-temp. However, still could be the soot (observations of non-sodium-containing objects are good data points!) if the cool object keeps the soot from being hot enough to glow. DMacks 13:56, 9 May 2007 (UTC)

variable

what are the ttwo different types of variables in experiments. And why aren't they mentioned in the variable article?

Are you thinking of dependent and independent variables? As for the article, it discusses the use of variables in an experiment in the introduction, but if you'd like you can link the article I did somewhere in that sentence. --Tardis 19:05, 8 May 2007 (UTC)

Variable#In_applied_statistics does already have wiki links to the in/dependent variable article. I think what confued the OP is that the article says "causal models" instead of "experiment". -- Diletante 23:09, 8 May 2007 (UTC)

I've heard 'key variables' mentioned occasionally, is this what you want :) I suppose there must be a name for non-key variables, but I forget what :( Sorry :( HS7 19:17, 8 May 2007 (UTC)

really need science help

This is not homework. It is coursework. OK, so it's almost the same, but I am supposed to ask for help, look on the internet, read encyclopedias. So I am doing all three at the same time and coming here. And I need to finish it very soon. I need help for both biology and physics. I mostly just need a website where I can find information about βradiation and about starch. I have searched the internet and couldn't find anything, so I am hoping scientists who spend a lot of their time on the internet (you) will be able to point me in the right direction. Can you try to avoid telling me to do my own homework, or I will probably have to ask again in a different way. I suppose what I really want is a science website that can tell me a lot about these two subjects. Thanks in advance from your help (unless you don't help). The end. —The preceding unsigned comment was added by 172.142.10.221 (talk) 19:14, 8 May 2007 (UTC).

If you want to learn about a subject here on wikipedia, just look up its article, like Beta decay and starch, wikipedia is first and foremost an encyclopedia. If you have a specific question that is not answered by those articles you can post it here. -- Diletante 19:24, 8 May 2007 (UTC)

i also find that another good site is [3]howstuffworks however this one is more focused on explaining something and might leave some stuff out. the articles here are very informitave and combining these two sites can hook you up with awsome material!Maverick423 Says Im in ur science steeling ur gravities 22:20, 8 May 2007 (UTC)

I think that helps, but one last thing, where can I find a list of isotopes that produce beta particles?

You want an isotope table. We have one here, and many more, with different kinds of information, are available online (although a few are not free). Of course, here's a hint: normal beta decay turns a neutron into a proton, which changes the ratio of N to Z. In most stable isotopes that ratio is somewhere between 1:1 and 3:2 (with the exceptions of protium, 0:1, and helium 3, 1:2). So, which isotopes (that is, what ratios) would be likely to "benefit" from going to N-1:Z+1? --Tardis 13:17, 9 May 2007 (UTC)

Yes, but I only have a few days to do it in.

Cards

Apart from games, tricks and balancing them, what fun things are there that I can do with cards? Bear in mind that I have a very broad definition of what is fun. If nothing much comes up here, I will probably resort to sorting them into order, especially if someone can suggest an interesting order to sort them into, instead of the obvious way. HS7 19:41, 8 May 2007 (UTC)

Shuffling and probability are always good choices...start with them sorted by value (four-of-a-kind clusters) shuffle repeatedly, seeing how many pairs remain after each. DMacks 20:13, 8 May 2007 (UTC)

Chris Ferguson can slice a carrot in half from several feet with a card. Useful if you're ever attacked by unruly vegetables. Or you could practice origami. Clarityfiend 20:56, 8 May 2007 (UTC)

It all starts with an Angry Salad. DMacks 21:04, 8 May 2007 (UTC)

Yes card throwing is cool. -- Diletante 22:29, 8 May 2007 (UTC)

My journey into cards started with a double lift. If you have even a passing fancy with playing cards I highly recommend reading a book, like "The Expert at the Card Table" by Erdnase, one of the seminal texts on card magic. Vespine 22:43, 8 May 2007 (UTC)

Encryption! The Solitaire (cipher) - as used in the (most excellent) Neil Stephenson book Cryptonomicon. Building a house of cards of course (well - I guess that's 'balancing' them). SteveBaker 01:11, 9 May 2007 (UTC)

You could shuffle the deck of cards again and again until they eventually wind-up in the original order. Of course, the odds of this happening are 1 in 52!, or 1 in 80 million trillion trillion trillion trillion trillion, so you could be there a long time... Laïka 13:04, 9 May 2007 (UTC)

(Or it could happen the very first time you try! There is no telling.) SteveBaker 14:58, 9 May 2007 (UTC)

Fortune telling - Tarot cards and all that. I'm pretty sure there are fortune telling methods that "work" with a regular deck of cards - although I can't find a reference for that right now. SteveBaker 14:59, 9 May 2007 (UTC)

It wouldn't happen the very first time, as the cards have be in a different order before you can get them back into the right order.

hello

how can you tell where I am just by my IP number? (172.142.10.221) I have seen it done on here a few times, but can't work out how. And how does the internet know where I am?

Our articles on WHOIS or ARIN might answer your question. But in case they don't, the simple explanation is that they are able to find the location of the server that your IP is registered to, not your actual location, just the location of the server--VectorPotential^Talk 19:48, 8 May 2007 (UTC)

For instance, you're using AOL, and the server you're connected to is located in Reston, Virginia. The server is registered to AOL, and is loacted in Dulles, VA. It's important to note however, that AOL uses a unique server setup that randomly connects you to servers all over the country, so running a WHOIS on a normal IP usually yields more information --VectorPotential^Talk 19:50, 8 May 2007 (UTC)

We also have an article on Geolocation software. --LarryMac 19:54, 8 May 2007 (UTC)

So I am connected to a server the other side of the world? What is the point of knowing where that is, if it doesn't tell you anything?

Who said there was a point? --18.214.0.135 14:56, 9 May 2007 (UTC)

Hypothetically, a network engineer could use such information to manage or fix network issues. A marketing engineer could use it to track aggregate statistics about the demographics of content subscribers. I can think of many similar "points" - it all depends on what you're looking for. Nimur 08:01, 10 May 2007 (UTC)

Well, the server knows where *you* are, which is extremely important, since otherwise it would be unable to send you all that data you requested. SamSim 14:59, 11 May 2007 (UTC)

Taking the question far to literally, there are lots of points, on the ends of each letter :@ HS7 17:56, 10 May 2007 (UTC)

Or taking it even more literally, knowledge doesn't require words, so there are no letters to have points on, except in the statement of the fact of that knowledge :@ HS7 18:19, 10 May 2007 (UTC)

And one final point, since each point in my first comment is on a separate letter, the aforementioned statement of knowledge would have to broken down into individual letters to show them as separate points, and most letters would then have to be broken apart :] Separating it into letters destroys the entire meaning of the sentence, and breaking a letter in half creates two more points, so everything has an infinite amount of points, unless the letters are broken metaphorically or imaginarily c:) HS7 18:23, 10 May 2007 (UTC)

May 9

stress transfer theory

you do not talk about stress transfer theory in plate tectonics —The preceding unsigned comment was added by 68.72.3.2 (talk) 01:47, 9 May 2007 (UTC).

I encourage you to be bold and add information you feel is lacking from articles, keeping in mind the necessity of adding verifiable content. I see that the plate tectonics article is currently protected from editing by unregistered users (a measure to deal with repeated vandalism), so your best course of action would be to explain what is missing (in detail, preferably) on that article's talk page. That way an established editor can add the missing information to the article. -- mattb 02:01, 9 May 2007 (UTC)

Pulse

Why is the heart a double beat whereas the pulse is a single beat? What is the most prominent pulse in your body and does anyone know what chamber initiates the pulse?

-I choose to remain anonymous

Might want to take a look at our Cardiac cycle page. The first part of your question is an interesting one! Think about what part or parts of the whole "double beat" cycle actually involve moving blood through the vessels you're feeling. DMacks 04:38, 9 May 2007 (UTC)

My pulse is often a double beat, especially if I measure it from my chest :) You usually only feel one beat as the other sends blood just to the lungs :) And I am quite sure it is the left ventricle that creates your pulse :) And you don't have to say you are anonymous, noone here knows who you are anyway, and signing will give just a munber, from which almost nothing can be found out about you :) HS7 11:59, 9 May 2007 (UTC)

...and which is already given in the history anyway. Getting a username here actually makes you more anonymous in some senses. --Tardis 13:06, 9 May 2007 (UTC)

motion in universe

Is it possible to stop moving? Say I take my spaceship and go to the least occupied part of the universe. Is it possible to just not move? If so, would I recognize that I've stopped moving? —The preceding unsigned comment was added by 69.42.16.90 (talk) 04:58, 9 May 2007 (UTC).

What you could do is cease all acceleration. There is no such thing as "not moving" as all motion is relative per special relativity. As in, you can only measure your motion relative to other objects, there is no absolute reference frame to judge one's motion. Someguy1221 05:49, 9 May 2007 (UTC)

I'm sorry, but what do you (and others) mean by "cease all acceleration"? It's bugging me. BTW, I'm not a physicist, so that's partly why I ask. It would seem to me that acceleration is subject to the same provisions as motion in terms of its measurements. Root⁴(one) 19:26, 9 May 2007 (UTC)

And the question I should have been asking is, what does "all acceleration" mean? Root⁴(one) 19:29, 9 May 2007 (UTC)

As i understand it, there is no least occupied part of the universe. And what you will find at any point in the universe is that objects will tend to be moving away from you as the universe is expanding. --Tbeatty 06:39, 9 May 2007 (UTC)

It's a meaningless question. There is no such thing as absolute motion - you can only ever measure your speed with respect to something else. Einstein, relativity, all that stuff. If you aren't actually accelerating - you can consider yourself to be stationary at any time and in any place - it simply has no meaning to say that. SteveBaker 14:55, 9 May 2007 (UTC)

Note, acceleration != motion. In Newtonian physics, a = dv/dt. if a=0, v can be anything (including 0). The earth is not accelerating (much) with respect to distance to the the sun (hopefully!) but it is moving at quite a speed. The problem is the definition of motion and lack thereof. Motion can only be observed with (at least) two entities and is meaningless to describe it otherwise. I'm having trouble seeing that Relativity really has anything to do with the concept of motion discussed here. To make some definition where "motion" is observed in only one entity X of would require some sort of God's-eye-view coordinate system of the universe and the entity X moving with respect to it (which we cannot see, and even if we could see, if we only had that fact -- motion with respect to the God's eye view -- in mind, and not position or any other fact on the God's eye view, we couldn't derive anything about anything else in the universe, so for all practical purposes this is meaningless). I also have trouble seeing how motion could be defined for three entities, if I try to define it, it appears to become something other than motion, or it doesn't fully describe the situation with respect to how the three entities are interacting. So how could I describe it for motion relative to everything in the universe?

If I'm hurdling to a brick wall at 100 mph, I could just as well say the brick wall is hurdling to me at 100mph! But if I remain at an equal distance to that wall for some time period, I remain "motionless" to that wall (and likewise the wall to me). I think that's all that any concept of motion can tell you.

Root⁴(one) 18:39, 9 May 2007 (UTC)

Acceleration means a change in direction or velocity. You can feel a real force when doing that (though it is equivalent to a fictional gravitational field, but let's not get into that!), unlike with inertial motion (i.e. motion at a constant speed/direction). So you can definitely not be accelerating (not changing in direction or speed) but you can always be said to have inertial motion. In any case the relevant article is principle of relativity (the reason why it matters in the article that the physical laws are the same in all frames is because if that can be shown to be the case then there is no physical way to tell who is moving and who is not. you can, however, tell who is accelerating and who is not) --24.147.86.187 01:24, 11 May 2007 (UTC)

Thank you! That was a much more eloquent explanation than I gave. SteveBaker 03:32, 11 May 2007 (UTC)

Thank you 187. That article's quite useful. Root⁴(one) 03:45, 11 May 2007 (UTC)

Questions about birthmarks

I have an area of abnormal pigmentation covering most of the back of my left hand. I have always described it as a birthmark. It's red and blotchy and much warmer than the surrounding skin; it looks a lot like the burst blood vessels you get with love bites. It is much lighter than a port wine stain. I read the Wikipedia article on birthmarks and mine doesn't seem to belong to any of the types of birthmarks listed. Are there other categories? Also, it appeared one day when I was six years old, but the doctor said it is still a birthmark, and they sometimes do appear that late. However, I can't find any information about this phenomenon online. I'm interested to know why a birthmark would suddenly appear, and how common it is. --Grace 06:11, 9 May 2007 (UTC)

From your description, it sounds like the blood vessels are closer to the surface of the skin than normal, causing the color change and the increased heat. Does this sound correct ? StuRat 06:41, 9 May 2007 (UTC)

Yes, that does sound right. Does that mean something? --Grace 12:18, 9 May 2007 (UTC)

It sounds most like a Macular stain (about which we don't have a specific article), but the timing of its appearance isn't really consistent with that. Birthmarks, by definition, don't just appear in children aged six. However, a doctor may have described it as being like a birthmark (in that it is essentially harmless). If you want to know for sure, a dermatologist would be likely be able to tell you. Rockpocket 06:54, 9 May 2007 (UTC)

I asked about this a few months ago. I was told it is a mongolian spot. --Kainaw ^(talk) 13:47, 9 May 2007 (UTC)

But Mongolian spots are very uncommon in white people (I'm white) and almost always disappear before puberty (I'm 23 and it has not faded). Also, those are blue to brown, and this is red, and the texture is different (based on google image search). It is not raised, but looks more like a rash than a solid area of color. I'm still confused... --Grace 23:51, 9 May 2007 (UTC)

Mine are (and have always been) red. They look like bruises and are not raised. I had them from the back of my head all the way down my spine as a child. Now, they are just on the back of my neck. My son has them also - just red. His are only on the back of his head. I'm mostly white, 1/4 Blackfoot (hence, the use of the nick that sounds like Kainah). --Kainaw ^(talk) 00:26, 10 May 2007 (UTC)

1/4 Blackfoot, does that make you a Lightgreyfoot ? :-) Could either of you have rosacea ? StuRat 07:22, 10 May 2007 (UTC)

Actually, I think I do have rosacea. I'm not sure if the birthmark could be related because my rosacea symptoms are confined to my face and I have only had them for a year or so. I suppose a dermatologist appointment is in order! --Grace 12:06, 10 May 2007 (UTC)

Yes, the dermatologist can tell you if both conditions are related. StuRat 14:51, 10 May 2007 (UTC)

I know that mine (and my son's) is not rosacea. First, it is on the back of the neck and down the spine - not on the face. Also, it does not come and go from one day to the next. It is a constant red splotch. --Kainaw ^(talk) 19:43, 10 May 2007 (UTC)

What's the L in L-ascorbic acid?

If you buy plain ascorbic acid (vitamin C) in the store, is that the same thing as l-ascorbic acid? Sorry for being dumb - I can't find anything in the vitamin C article that addresses the meaning of the L. --Grace 06:29, 9 May 2007 (UTC)

I believe that means levorotary (as opposed to dextrorotary). StuRat 06:35, 9 May 2007 (UTC)

The fairly comprehensive Enantiomers article where StuRat was is a good source, as is the "Naming conventions" section of our Chirality (chemistry) article. Need to be very careful here—are we talking about a lower-case letter "l" (levorotary, a physical property involving how the molecule interacts with light) or the unrelated capital "L" (a structural geometry, not a physical one)? The "L" form of ascorbic acid—the biologically active one—has a positive optical rotation, therefore it's "d" not "l". Assuming you're buying "plain ascorbic acid" in the context of a vitamin supplement or nutrient, it's probably almost certainly that L one. DMacks 06:50, 9 May 2007 (UTC)

Thanks for the clarification. StuRat 07:15, 10 May 2007 (UTC)

Life on(to) Mars

What sort of precautions, if any, are taken to make sure that bacteria and other small organisms aren't carried to Mars on the probes and rovers and such that we send there? Dismas|^(talk) 08:43, 9 May 2007 (UTC)

They bake the spacecraft to sterilize them prior to launch. It's never perfect though.[4][5] And Mars and Earth exchange rocks anyway; some bacteria may have taken a natural ride during the last 4.5 billion years. We could all be one big happy family, Martians, us, and the rest of the universe. Weregerbil 12:29, 9 May 2007 (UTC)

I can see how Mars rocks get to Earth, but wouldn't any Earth rock dislodged from Earth be vaporized in the process and burn up before it escaped from Earth's atmosphere ? StuRat 23:15, 9 May 2007 (UTC)

Here is an interesting article on space.com relating to this question. --LarryMac 18:12, 9 May 2007 (UTC)

See also planetary protection. Icek 10:54, 13 May 2007 (UTC)

Mobile phones

Can mobile phones damage your brain. I have one and use it quite alot. —The preceding unsigned comment was added by HappyEater (talk • contribs) 09:03, 9 May 2007 (UTC).

See Mobile phone radiation and health. --Shantavira 11:52, 9 May 2007 (UTC)

Executive summary: we don't have a lot of reason to believe that it does, but we don't really know. -- mattb 05:27, 10 May 2007 (UTC)

Hot air balloon speed

Settling a dispute between a buddy of mine and I. In a hot air balloon, in say, 25 mph of wind, how fast would you be traveling? My understanding of it is, since any energy transfer (kinetic energy of the wind -> kinetic energy of the balloon) includes loss due to entropy, drag, all that, you'd never attain the same speed as the wind, while he contends that the balloon travels at the exact same speed as the wind (or effectively the exact same, the difference would be minimal). Thoughts? Especially with links to back it up? -M^ask? 10:52, 9 May 2007 (UTC)

Thought: Balloons are less dense than the air surrounding them (or in approximate equillibrium) and have immense surface area. They would be very responsive to changes in the wind.--138.29.51.251 12:16, 9 May 2007 (UTC)

Any drag the balloon experienced would tend to raise or lower the balloon's speed to exactly match the wind speed (at which point there would be no more drag). The experience on the ballon in a steady wind is "dead calm".

This is slightly different than for a sailboat running downwind; the sailboat contacts the water (which imposes a different drag force vector on the boat than does the air) so a sailboat typically approaches but does not quite match the wind speed.

Atlant 12:53, 9 May 2007 (UTC)

Yeah - I agree. At the point you launch the balloon, it's moving at 0mph relative to the ground - but 25mph relative to the air. It'll very rapidly gain speed (relative to the ground) and lose it relative to the air - until it's going very close to 25mph relative to the ground and is almost stationary relative to the wind. In a sense you are both right. As your buddy says: If you measure the speed of the balloon after it's been up there for 10 minutes, it'll be so close to 25mph that there is no instrument you'd be likely to have that would tell you any different - especially given that the air is a little turbulent and will vary depending on the terrain you are crossing so in reality this isn't an exact science. However, you are also technically correct - in an idealised perfect world with perfectly smooth airflow - the balloon would never quite reach 25mph - it'll be 24.999999999999 mph or something. Let your buddy win this one - you are being ridiculously pedantic! SteveBaker 14:50, 9 May 2007 (UTC)

If it's in a steady wind for an extended period of time, it's speed relative to the ground will be the exact same as the speed of the air relative to the ground, for all practical purposes.  Adam2288  T  C  17:59, 9 May 2007 (UTC)

if, however your talking about convayences in general, it is easy to go above the wind speed in a sailboat.--Hacky 20:41, 9 May 2007 (UTC)

Dead downwind?

Atlant 23:21, 9 May 2007 (UTC)

Yes - dead downwind. We should be rigorous and replace every instance of the word "speed" in the previous answers with "velocity" - which expresses "speed and direction". SteveBaker 11:03, 10 May 2007 (UTC)

Steve, I couldn't understand the "polarity" of your answer. AFAIK, a sailboat can only approach and never even equal the velocity of the wind when the sailboat is sailing dead downwind. There's no way it can exceed the velocity of the wind.

Atlant 12:32, 10 May 2007 (UTC)

(Sorry - I missed the 'topic switch' to sailboats - I was still talking about balloons). SteveBaker 21:18, 10 May 2007 (UTC)

Yes, but at an angle of about 100° to the wind, it can easy go faster see sailing "Some extreme design boats are capable of traveling faster than the true windspeed." --204.234.208.164 16:45, 10 May 2007 (UTC)

Right. If you represent the sailing ship by a ball sitting in a groove that it can roll up and down and represent the wind by a long straight-edge at 45 degrees to the groove. As you move the straight-edge forwards, the ball (because it's constrained to roll along at 45 degrees to "the wind") moves about 1.4 times faster than "the wind". The trouble for sailboats is that there is no "groove" for them to sit in. But the long, deep keel sticking down under the boat effectively forces it to move through the water in whatever direction it's facing instead of sliding sideways parallel to the direction of the wind. So if the keel works well enough - the boat can theoretically move at almost any speed. However, in reality, the keel doesn't keep the boat "in the groove" very well at all - so you can only beat the wind speed if you get the angle just right and everything is set up optimally. But our balloon can't do that - unless it has something dangling down and fixed on the ground somehow - there is no way for it to stay "in the groove" - so it just moves parallel to the wind and at the same speed. SteveBaker 21:18, 10 May 2007 (UTC)

See Leeway for a discussion of the problem that sailboats face in trying to stay "in the groove".

Atlant 22:18, 10 May 2007 (UTC)

Meh - that's a pretty terrible article. SteveBaker 23:55, 10 May 2007 (UTC)

Many article improvements have arisen from Reference Desk discussions... (hint, hint)

Atlant 13:29, 11 May 2007 (UTC)

Converting alcohol to alkene

There was an exam question that asked for a way to convert an alcohol to an alkene without using dehydration or elimination. Does any body know any other methods with which such a conversion can take place?Bastard Soap 12:16, 9 May 2007 (UTC)

Apparently not. 209.53.181.172 21:35, 9 May 2007 (UTC)

I don't know, but I'd bet that nature has found a way using [enzymes]... Aaadddaaammm 01:27, 10 May 2007 (UTC)

What level of academia are we talking here—isn't "dehydration" just a specific type of "elimination"? How about oxidize to a ketone/aldehyde, then Wittig or Julia coupling? Or convert that carbonyl to an enol triflate and reduce off the oxygen functionality? Or cheat: convert the alcohol to a tosylate and displace with allyl Grignard:) DMacks 02:26, 10 May 2007 (UTC)

I have no idea of what you just said... so I guess you are at a much higher level than I am. What would happend if you passed a current through the alcohol? Bastard Soap 11:14, 11 May 2007 (UTC)

Own sweat smells nice.?

Okay weird question. As my understanding goes, we find other people's smells attractive because their genes are different to ours. The more genetically different they are, the better they smell. However, I tend to find my own smell attractive... or at least not offensive. Where by my logic I would assume that my own smell should be the least attractive to me, as I have the exact same genes to me, and so I should be attracted to someone who is the same as myself, as this offers no advantage from the point of view of genetic mixing. More worrying, does this mean that i will find someone with similar genes to me more attractive in this sense? Or, is it just the case that I am familiar with my own smell? Or is it that the gene-smell test only works in the case of early encounters - but you can get used to an offensive smell and find it comforting?? Will be glad to hear your thoughts.. Or even if we have an article on the topic. 213.48.15.234 13:18, 9 May 2007 (UTC)

Your assumption is flawed. It is just as common for a person to find another person's smell attractive as it is to find the other person's smell offensive. Much of a person's odor comes from what they eat. Use of deoderants and perfumes also have a huge effect. I work in a highly mixed group of people. I have heard many complaints of the "stink" of others because they eat too much fish, or they don't use deoderant, or they use too much hair straightener, or they wear too much flowery perfume... --Kainaw ^(talk) 13:45, 9 May 2007 (UTC)

I saw a program once where they got a group of men, halve very attractive and have very unattractive, to do vigorous excercise. They then wrapped dolls in the mens t shirts and got 4 female models to come and smell the dolls, choosing which ones they prefered the smell of. every model chose the smell from the unattractive men. So your theory sounds right to me. And of course from an evolutionary point of view things like perfume and hair spray have been around a lot shorter time than we have been smelling each other. Anya Fox89.241.20.220 14:11, 9 May 2007 (UTC)

I think the pheromones in sweat have nothing to do with genetic difference. [Mac Δαvιs] ❖ 17:01, 9 May 2007 (UTC)

Buzzer word : think. As for myself perhaps their is an influence from the genome of someone on the pheromone emitted in sweat, but that's entirely an personal opinion on my side and I don't have any scientific paper on the subject to show you. -- Esurnir 17:51, 9 May 2007 (UTC)

The facts are that the situation in humans are not fully understood. Seperating the innate response to odors from the associative response is extrememly different. Also, most human societies have strong pressures to mask natural odors with sweet smelling perfumes or deodorants, therefore we have been socially conditioned from a very young age. Nevertheless, there are some studies that suggest humans do (or once did) use odors as social cues. For example, the Yanomami people will rub the body of someone they have encountered and then sniff their fingers (Schaal & Porter 1991).

T-shirt tests (as described above) seem to suggest that we can distinguish between those who have a similar or dissimilar Major Histocompatibility Complex class (MHC) to ourselves, a mechanism that would permit us to find a mate that is genetically distinct based on their odour. Interestingly, females on the contraceptive pill appear to find those with a similar MHC class attractive while those not on the pill find those with a dissimilar MHC class attractive (Wedekind, 1995). The classification of what is considered visually "attractive or unnattractive" in men (as described by anon above) was linked to facial symmetry. Woman only preferred the odour of "attractive" (symmetrical) men in the period of fertility during ovulation. During periods of low fertility, they showed no preference. However, between a quarter and a third of people can repeately identify their own body odour from a choice of 10. A similar proportion can detect their sexual paterner's odor in a similar test. Women tend to be better at this than men (Schleidt, 1980). So seperating a previous association with an odor which results in a conditioned preference, from an innate preference, is near impossible in humans, which is why scientists use animal models.

There is so much data on animal pheromones in the literature, most of it crappy, but some reputable studies have shown that mice do distinguish between MHC class peptides in an innate, non-learned manner. They do so via a specific receptor expressed in their vomeronasal organ (VNO). The problem with interpreting this data with regards to humans, is that humans do not have a functional VNO, and thus this mechanism seems unlikely to be conserved. The Holy Grail of olfaction research is to demonstrate that humans do have a mechanism for pheromone detection and then to find the pheromone compound that activates it. If you wish to learn more about this, a really nice overview can be found in Pheromones and Animal Behaviour by Tristram D. Wyatt. Rockpocket 18:20, 9 May 2007 (UTC)

yeast

how can you tell whether yeast cells are dead? Basically I need to conduct an experiment in which I will need to know whether any cells in a sample of yeast are still alive. I thougt just putting them underwater and waiting for the bubbles to stop, but I suppose they would produce ethanol then, and all get drunk and die. Are there any other reasonably easy and feasible ways to see if the cells are alive?

See [6]Wikibooks Cookbook: Yeast. If you add yeast to warm (110 degree F) water with sugar added, it will foam in a few minutes if the yeast cells are alive. The process is described better at Ochef.com.[7]. The temperature is critical, so if you are doing an experiment, this is an independent variable you should control accurately. Guessing whether the water is warm versus hot is not as easy as one might assume. Edison 15:13, 9 May 2007 (UTC)

Expanding on what Edison said, this process is called proofing (or maybe proving) the yeast. Bakers who aren't certain their yeast is still fresh routinely do this.

Atlant 16:18, 9 May 2007 (UTC)

actually temperature is the variable I am measuring.

You could use a stain that only stains dead yeast cells. And look at it under a microscope. 62.194.90.107 16:10, 9 May 2007 (UTC)

If you happen to have access to a fluorescence microscope, there are several yeast-specific Live/Dead staining kits available. A couple of those are listed on this page. --mglg_(talk) 18:55, 9 May 2007 (UTC)

Really what I wanted was something that would show whether the yeast was alive or not. I have to cook them until they are all dead, and have no idea how to tell. I expect looking at them under a microscope will be too complicated and take too long.

What grade are you in? I think people are being a bit too tricky here. It's easy to massively overheat the yeast, and then prove that they don't 'proof'. --Zeizmic 20:03, 9 May 2007 (UTC)

I agree. Boil them for 5 minutes, and they'll be dead as Dillinger, guaranteed. --TotoBaggins 20:14, 9 May 2007 (UTC)

How about using the yeast to make bread ? If it's alive, you have a nice loaf of bread. It it's dead, you have matzo bread. StuRat 22:18, 9 May 2007 (UTC)

Are therre any chemicals I can pour into the yeast that will make them look different if they are alive than if they are dead?

I've given up on this and gone for the easy option of using a respirometer.

Zip line speed

I need to make a zip line for a show I'm doing and I need to know A) pythagorus theorum so I can work out the height from the ground to the zip line, at any given point on the zip line, so that things can pass under it. and B) the equation to work out the speed that an 8 stone person will travel over a given distance and height. My two towers are roughly 7 metres and 5 metres tall across a 50 metre distance thank you Anya Fox89.241.20.220 14:05, 9 May 2007 (UTC)

The formula you asked for is simply a²+b²=c². However, that will not help you. You will likely only have the distance of an object from one of the towers. So, you only know one of the variables. Instead, you know that the ratio of the height to run is 2/50. So, to calculate the height at another run (distance from the 5 meter tower), you use H/D = 2/50 or H = (2D)/50 where D is the distance from the 5 meter tower and H is the height from the top of the 5 meter tower to the line. Add 5 to H and you have the height from the floor to the line.

Keep in mind that this will not be accurate. 50 meters is a long run for a zip line. It will sag a lot. Add a person to it, and it will likely drop below 5 meters a good 2/3 way from the 7 meter to the 5 meter tower. Of course, that means that the speed of the person will be zero since he will only drag about 30 meters across the line and then stop. --Kainaw ^(talk) 14:14, 9 May 2007 (UTC)

Assuming a completely rigid zip-line (ie; that it won't sag: not exactly true, but I can't find any more accurate models of the situation), the acceleration of a person zipping down the wire would be $a=sin({\frac {2}{\sqrt {{2}^{2}+{50}^{2}}}})\times g$, where g is the acceleration due to gravity, roughly equal to 9.8 and the ${\sqrt {{2}^{2}+{50}^{2}}}$ comes from Pythagoras theorem (given above). It looks ugly, but as the angle in your zip wire will be only very slight, so only the acceleration of the object will only be slight, and can be worked out at 0.39 ms^-2. However, the speed can then be calculated by $v={\sqrt {2as}}$, where s is the distance travelled by the person in metres (the angle in the wire is so slight, you can simply assume that s is the distance from the bigger pillar). This eventually works out that, when the person reaches the end of the wire, their speed is 6.24 metres per second, or 13.95 miles per hour; that's still pretty fast! Laïka 16:01, 9 May 2007 (UTC)

For the idealized expression above, a simpler equivalent is $a=tan(2/50)\times g$. However, this will not be useful in practice for the reasons given below. --Anonymous, May 10, 06:06 (UTC).

You are neglecting both air resistance and friction. Air resistance would be pretty negligable at those speeds - but friction in a zipline isn't. Te effect of a slightly saggy cable ought to be beneficial since it'll make the cable steeper to start with (more accelleration - more speed to start with - hence more excitement) - and will then make it level out and perhaps even head uphill slightly at the end - which will help to decelerate the rider before the big "kersmack!" at the end. That being the case, if the zipline does seem to fast at the end, it may be worth slackening off the cable a bit to simultaneously make the ride more exciting - and slow it down where you need it to be slower. SteveBaker 19:20, 9 May 2007 (UTC)

The hang of cables without any additional weight follows that of a Catenary. As far as how a a cable hangs with something hanging from it, that sounds a little bit like one method to draw an Ellipse (see figure drawing on article). Root⁴(one) 20:04, 9 May 2007 (UTC)

I wonder how heavy the cable is? If it's nothing compared to the rider - then you're right - a section of an ellipse would be a better model than a catenery. But if this is a heavy steel cable, it might easily be much heavier than the rider - which would make the catenary curve a better model. SteveBaker 22:42, 9 May 2007 (UTC)

Olive plants

Just curious: can I grow an olive tree from the core of an olive? From green olive in brine that are sold as food? Does it require some dormace breaking? 84.160.229.65 15:20, 9 May 2007 (UTC)

Since salt is toxic to land plants not accustomed to it, like olives, I would very much doubt if you could get it to germinate once it has been soaked in brine. StuRat 22:11, 9 May 2007 (UTC)

I doubt that salt affects seeds, at least not in general. The olives are not supposed to germinate while in the brine. Some other seeds have to endure bush fire or the inside digestation of varius animals to break dormancy. After all the olives have not been put with pizza in the oven. 84.160.220.235 19:15, 10 May 2007 (UTC)

Anti missile defense in Europe and Booster phase ICBM interception

I was wondering, reading an article about the freezing relation between Europe and Russia that it was mainly based on the decision of eastern country to accept base of ABM.

While I see the use of those interceptor for intercepting (official reason) nuclear ballistic missile from Iran heading toward Europe. I was wondering if abm placed at the most eastern part of Europe (think baltic country, Poland, Ukraine) could intercept ICBM during their booster phase ?

Note the booster phase of an icbm is the phase where the icbm is still a "rocket" and is the easiest (due to the low speed of the icbm during that stage) place to intercept it.

I was asking this question as I'm a total noob in the icbm ballistic trajectory. If the trajectory is like "firing a shell" a nice parabolic curve, then it would be "doable" to intercept the icbm during the booster phase. But perhaps the trajectory would be more "square" like with a missile going nearly straight up to make it toward space then the warheads go ballistic during a flat trajectory before rentering the athmosphere and drop like a thermonuclear anvil

I assume the trajectory of an icbm is on middle ground between those two projection. So intercepting an icbm during booster phase with abm in eastern europe "doable ? Or not doable ?" -- Esurnir 17:47, 9 May 2007 (UTC)

As far as I know about the trajectory, the ballistic missiles follow an elliptic path having the center of the Earth as a focus. This [8] site seems to have some interesting infos about missile defence. --V. Szabolcs 18:27, 9 May 2007 (UTC)

Shells don't really follow a parabolic path; that's a simplification based on (1) ignoring air friction and (2) treating the Earth as flat. If you continue to ignore air friction, but allow for the curvature of the Earth (so that the direction of gravity changes over the flight of the shell), then the path is really an ellipse. And the same applies to a rocket once it stops thrusting, i.e. when it is "ballistic".

The problems with intercepting a missile during boost are, first, that's when it's farthest away, so you would need a really powerful launcher on your ABM to cover the distance to the launch site in a short enough time; and second, whatever you use to detect it has to be able to detect it that much faster. Having said that, I have no idea of the capabilities of military systems in these areas today. --Anonymous, May 10, 06:15, copyedited 08:15 (UTC).

But during launch, the target missile is going at its slowest - that gives you the best chance to hit it - and it can't deploy multiple independent re-entry vehicles and decoy balloons as it can on the way back down again - so the risk of you shooting down a bunch of decoys is eliminated. Also, your anti-missile missile ought to be a lot lighter than the target vehicle - it doesn't have to have enough fuel for a long range trip - and it can have a vastly smaller payload - this ought to give it much better accelleration than the target - and hence in a race, the anti-missile ought to be able catch up with the target fairly swiftly. Best of all, if you blow a nuclear weapon apart on the way DOWN, you shower the target area with radioactive junk - but if you smash it to bits on the way UP, it's the launch site that gets showered with radioactive debris - and I suspect you'd greatly prefer that scenario! If I were designing such a system to counter threats from relatively low-tech places such as North Korea, I'd mount my anti-missiles on high altitude helium balloons or on satellite-based launchers (although the latter would be illegal under international law). SteveBaker 23:02, 13 May 2007 (UTC)

The best place to learn, of course, is The Missile Defense Agency, since they will be overseeing any such construction. In general, different types of interceptors are effective for each of the phases of ICBM flight - boost, mid-flight, and re-entry/detonation. So in the most practical sense, the engineers will tell you that a mid-course interceptor is "not designed" for boost interception. This may mean that the radar can not track the target fast enough, or that the interceptor kill vehicle can only destroy the ICBM in certain configurations (many are kinetic kill vehicles which do not use explosive, and this puts some limitations on where it will be effective). Any numerous other engineering issues could naturally come up; you will get a better perspective if you learn about the basics of ballistic missile defense. This site gives a pretty decent introduction to the technology in use today. Nimur 08:12, 10 May 2007 (UTC)

Last night's episode of House - medical question

Last night's episode of House featured a particularly gory scene where an 'infection' (never actually specified) caused the back of a young woman's skull to spontaneously split open, exposing the brain - following only a very brief period of agony with no related symptoms beforehand. As I understood it, the back of her head just 'popped'.

So, is this just an example of medical/body horror - or is there really an infection out there that can do this?

I'm aware that there are infections that consume flesh and bone - but surely they cause *pain*, or have other symptoms (that would be noticed in a patient in a large, well-equipped hospital under the care of The World's Greatest Doctor(tm)) before it gets to the stage of cracking open heads?

I am also aware that the writers of House have not always strictly been 'medically accurate' with their scripts - but AFAIK, they've never actually gone as far as 'making shit up because it looks cool/gross'. --Kurt Shaped Box 20:45, 9 May 2007 (UTC)

Not an explosion, but a massive and disgusting insult to the brain that the patient was unaware of: a man ... suffering from an unusual form of cancer which had eaten away at the upper portion of his skull and scalp but who had not sought any medical treatment because the condition was not causing him pain. Link. --TotoBaggins 21:45, 9 May 2007 (UTC)

Hmmm - "No pain, no brain" eh?! Well, you don't actually feel pain from trauma in the brain - so the "no pain leading up to it" makes a certain kind of sense. SteveBaker 22:37, 9 May 2007 (UTC)

I don't think that there was actually any brain trauma. They patched her up (metal plate?) and she was physically fine eventually, once the underlying condition been correctly diagnosed and treated - it didn't seem to actually come from the brain, rather the skull itself. --Kurt Shaped Box 22:48, 9 May 2007 (UTC)

It wasn't an infection, it was cleaning fluid, remember? [Mac Δαvιs] ❖ 00:05, 10 May 2007 (UTC)

Na, it was downing the cleaning fluid in a gel-cap that caused the infections - the scar tissue in her stomach made a bridge between a vein and an artery, allowing various bacteria to go where they shouldn't in her body. --Kurt Shaped Box 00:10, 10 May 2007 (UTC)

Suger on paper

Im a clutz and I dropped a beaker full of a .1 Molar souluton of sucrose in water all over some papers. it was boiling on a hot plate. The papers are very important, and I would like to know if anyone knows of a solvent that can be used to take the glossy/sticky resedue off them, without damaging the paper itself. the paper is standerd lined notebook paper, written in pencil. I have acsess to many chemicals. —The preceding unsigned comment was added by Hacky (talk • contribs) 20:51, 9 May 2007 (UTC).

Er, boiling water got it on, how about boiling (or at least warm) water to get it off? Pencil-writing isn't usually water-soluble. DMacks 20:55, 9 May 2007 (UTC)

Note that boiling water has a nasty habit of turning paper into pulp, however. TenOfAllTrades(talk) 21:07, 9 May 2007 (UTC)

Glucose is apparently soluble in 2-methyl-2-butanol at 30°C,[9] which should allow a quick washing of the sheets without them being damaged (adding Dimethyl sulfoxide makes the solvent even more effective, but be warned that it has the odd effect of triggering a taste reaction of oysters on skin contact, and it may also strip the graphite off the page!). I'd recommend if possible making up some fake sheets, just with some scribble, and testing the solutions on these before using them on the real thing. Laïka 21:54, 9 May 2007 (UTC)

How about if you enclose each page in two sheets of clear plastic (overhead projection floppies should work), so they don't stick to anything else. You can then keep the papers like that, or, if you prefer, you can photocopy them and toss the originals. (This might be a good idea, as sugar-coated pages could attract vermin and varmints.) StuRat 21:59, 9 May 2007 (UTC)

Photocopy the papers and use the copies, notarized if necessary?

Atlant 23:27, 9 May 2007 (UTC)

Encyclopedia of Life

The Encyclopedia of Life is up and running for anyone who does not know. 71.100.2.43 21:37, 9 May 2007 (UTC)

Well, it is and it isn't. There isn't actually an encyclopedia there in any shape or form yet. Skittle 21:46, 9 May 2007 (UTC)

No it's not, and even if it was, this reference desk isn't the place to advertise such projects, even cool ones. --TotoBaggins 21:48, 9 May 2007 (UTC)

I just hope it has a Wikipedia-compatible license. —Pengo 23:48, 9 May 2007 (UTC)

So much for wikispecies. --Russoc4 03:22, 10 May 2007 (UTC)

.... or is it? Apparently "The Wikimedia Foundation is a member of the Encyclopedia’s Institutional Council." [10] Perhaps there will be a merger... Nimur 08:16, 10 May 2007 (UTC)

Liver Cleansing/Detox Foods???

Is anyone familiar with changes that can be made to your diet to help cleanse the liver? So far the only things that I can come up with that seem credible are 1. lots of water 2. lots of 'whole foods' like fruit and veggies and 3. have a low fat diet. Any insight would be great! Thanks ~ Ashley604 ~

Um, I'm not sure why the liver needs "cleansing", or how changing your diet will do that. Talk to a medical practitioner for medical advice. Splintercellguy 23:54, 9 May 2007 (UTC)

Actually, yeah, I used to think the detox thing was a good idea and made sense, but I've been reading more and more that it's just a big commercial scam. There is no such thing as cleansing or detox, toxins don't build up and doing a detox doesn't get rid of them and doesn't mean you start from scratch. If you go back to your old eating habits you will be exactly where you started before your detox. Generally, a healthy diet is healthy for your liver too, I don't know of any specific diets to target the liver, but I do know it's definitely NOT Atkins diet. :) Vespine 00:28, 10 May 2007 (UTC)

Still, for completeness you may want to see the article on Sandra Cabot, which includes some details of her version of the liver cleansing diet. Confusing Manifestation 01:07, 10 May 2007 (UTC)

Do not talk to a "medical practitioner" about this. Talk to a "folk medicine practitioner". What you are asking about has nothing to do with what doctors and scientists mean when they use the word "liver". You don't expect an MD to adjust your chakras, do you? Most of us wish the quacks would make up their own words instead of using ours for entirely different concepts. alteripse 02:53, 10 May 2007 (UTC)

Next you'll be telling me I don't have 40 year old cornflakes in my colon! - Nunh-huh 03:55, 10 May 2007 (UTC)

Any of these "cleansing" diets will all have one thing in common: they tell you to drink large, large quantities of water. Guess what actually wicks toxins out of your body? That's right! Most toxins are exuded through sweat or passed out of the body through urine. Thus, drinking the FDA recommended amount of water every day is the best "cleansing" technique. Any of these fads that proscribe this food or that pill are just taking money from you in exchange for a placebo. -- Kesh 05:31, 10 May 2007 (UTC)

I like to cleanse it under running water and fry it with some onions. A nice chianti and some fava beans finishes it off.

It isn't normally necessary to "cleanse the liver", just eat a healthy diet and you will be fine. There are exceptions, however, requiring emergency medical care, such as the chelation therapy used if you ingest poisonous heavy metals. StuRat 07:12, 10 May 2007 (UTC)

As several people have said lots of water is the universal body cleanser. That being said, is certainly possible to cleanse the gallbladder and indirectly the liver. Clearing the gallbladder allows anything that is backed up in the liver to come out into the gallbladder. You can find several procedures here. The prodecures mostly boil down to this:

1. Eat extremly low fat for a couple of days in order to have bile build up in the liver / gallbladder.

2. Drink nothing but juice the day of the cleanse.

2.5 You may like to flush with epsom salts a couple of hours before the next step. (1 tablespoon mixed with 1/2 cup water + drink about a quart of water extra.) Tastes nasty, but will flush through your system

3. Evening of Cleanse drink 1/2 - 1 cup of olive oil (you may mix with fresh lemon juice). Lay down on your right side so the oil can penetrate the gallbladder. The oil will stimulate the bile and lubricate gallstones so that they will be expelled.

4. The morning after you should pass gallstones. If you flushed with epsom salts then you shoould have very little stoolo, and the stones will float on the water in the toilet. They may be rice to bean sized or larger, colored vivid green to yellow or black.

There are more detailed procedures listed on the site referenced above. I can tell you from personal experience that this does really work, you should pass gallstones, unless your gallbladder is seriously blocked. Also, I had no pain involved, although I didn't like the taste of the epsom salt flush. Personally all of the stones I passed were rice to pea sized, but I would rather pass them now than have to have my gallbladder removed when they are the size of eggs.-Czmtzc 12:36, 10 May 2007 (UTC)

Wow, never heard of that. But wouldn't drinking a cup of olive oil give you pancreatitis? Anchoress 12:53, 10 May 2007 (UTC)

I would want to be sure I actually had gallstones before putting myself through that, and would also check with a doctor before drinking large quantities of olive oil and/or Epsom salts. This treatment may also give you temporary diarrhea. StuRat 14:46, 10 May 2007 (UTC)

Crap. Just crap. Drinking olive oil results in formation of fecal globules by a process of saponification. It comes on through, and is vastly interesting to fools who are taken in by this nonsense. I am sure if you ask, czmtzc will offer you a cure for the evil eye as well. alteripse 23:52, 11 May 2007 (UTC)

Question on Humanities Desk

I asked a question on the humanities desk, here. However, while the question fits the humanities desk, I think most of the people who are likely to know the answer frequent the science desk. So I hope it's okay to link like this :-) Skittle 23:01, 9 May 2007 (UTC)

Darwin's Domestic Pigeons

The first chapter of Charles Darwin's hugely significant book The Origin of Species discusses Darwin's hobby of pigeon breeding and domestic pigeon breeds such as the English carrier and the short-faced tumbler. I recently came across a drawing of just a few pigeon breeds (1.8 MB jpeg) and found, like Darwin, "The diversity of the breeds is something astonishing".

Wikipedia is sorely lacking in images (or articles) on the vast majority of pigeon breeds, and it's a pity that we don't even have the breeds mentioned specifically by Darwin as articles, photos or drawings. I suspect that the drawings in the book linked to above have fallen into the public domain, but the book lacked a source. However, there must be a large number of public domain drawings, at the least, of the breeds around in Darwin's day, and I'm sure there must be some pigeon fanciers around today?

This is a call for photos, drawings, etchings, etc, and for anyone interested in writing articles on the animals which launched Darwin's thesis on natural selection, which has become the cornerstone of biology today.

And finally the question: are these breeds still around today? —Pengo 23:46, 9 May 2007 (UTC)

There are still pigeon fanciers today though I'm not sure it is as popular as it was in Darwin's day. There are a number of pictures of specific breeds of pigeons in Darwin's The Variation of Animals and Plants under Domestication which is now wholly in the public domain. --24.147.86.187 00:30, 10 May 2007 (UTC)

And available from Project Gutenberg: http://www.gutenberg.org/etext/3332 Rmhermen 03:05, 12 May 2007 (UTC)

Gutenberg's scans really aren't that brilliant, but it's a start: —Pengo 16:40, 12 May 2007 (UTC)

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May 10

Constellations of stars

where to look for it : the Big Dipper, the Little Dipper, the Orion and the Andromeda? —The preceding unsigned comment was added by 72.187.17.165 (talk) 00:08, 10 May 2007 (UTC).

I'm not sure what it is that you're looking for: we have articles on the Big Dipper, the Little Dipper, Orion, and Andromeda. We also have an article on star chart that will link you to a useful star map. Let us know if you were looking for something else. - Nunh-huh 00:19, 10 May 2007 (UTC)

Stellarium is my favourite way to locate things in the sky. It's the easiest star software for beginners because it very closely mimics what you actually see with your eyes. Vespine 00:21, 10 May 2007 (UTC)

Where to look for these in the sky depends totally on where you are on earth, and the time of year. Orion, in particular, is not visible all year from most places, though it is unmistakable. Get yourself a cheap pocket planisphere from anywhere that sells telescopes.--Shantavira 08:50, 10 May 2007 (UTC)

Measuring Potential Difference

File:Reduction-potentials2.PNG

When in doubt, use electrochemistry!

Hello. If electrons are not flowing into the circuit, is it possible to measure the potential difference across the terminals of the dry cell? Thanks. --Mayfare 00:31, 10 May 2007 (UTC)

In theory: no. In practice: no. Please see voltmeter. To measure a voltage, one needs a current. With an exceptionally good insturment, the current can be exceptionally small, but some electrons must flow. -Arch dude 01:41, 10 May 2007 (UTC)

An electrostatic voltmeter draws no current (not even a little bit). Also see potentiometer for measuring voltage: no current is drawn at balance. —The preceding unsigned comment was added by 88.110.183.42 (talk) 02:03, 10 May 2007 (UTC).

Well, no continuous current. There's still a transient, and probably a very small leakage current. -- mattb 05:20, 10 May 2007 (UTC)

The link is at electrometer. And in principle, a virating-reed electrometer could draw no current, not even a charging current (if the vibrating reed were placed near but not in contact with the already-charged object). Electrons would flow on the charged object but none would "leave".

Atlant 12:30, 10 May 2007 (UTC)

So many electrical engineers and so few chemists! You could calculate the electric potential based on the concentrations of the chemical in the battery. See dry cell for the OP's question, and electrochemical cell for a brief discussion of how to do this. Nimur 08:19, 10 May 2007 (UTC)

There are quantitative details at Standard electrode potential, with examples, and this handy chart. Nimur 08:21, 10 May 2007 (UTC)

A potentiometer in the older sense was a bridge device with a standard cell, a slidewire and a galvanometer. The standard cell furnisshed a relativly constant voltage with a correction for temperature. Certainly tiny currents flowed from the standard cell and the external source of EMF to be measured as the slidewire was adjusted to null the current, but it was likely microamperes or less. At the instant when the voltage was said to be "measured," i.e. determined, no measurable current would be flowing, as shown by the non-deflection of the galvanometer. A modern digital voltmeter such as the Fluke 87V has a 10 megohm input impedance, so is if is measuring say a 1.5 volt emf, it would draw 0.15 microamperes. If it were measuring the max allowable voltage of 1000 volts, it would draw 100 microamperes. In a potentiometer bridge circuit, this could be reduced to a fraction of a microampere.Vacuum tube voltmeters from the 1940's on had this high or higher input impedances. Edison 16:05, 10 May 2007 (UTC)

Shouldn't it be 'yes', it is possible to measure the potential difference, but it will be 0 :] HS7 17:54, 10 May 2007 (UTC)

HS7: No, it is not zero. The potential difference is unquestionably there when there is no current flowing; the question was whether it can be measured without drawing current. --169.230.94.28 00:58, 11 May 2007 (UTC)

Principle,law,hypothesis,theory.theorm

What is the difference between principle, theory, theorm, law and hypothesis? —The preceding unsigned comment was added by Invisiblebug590 (talk • contribs) 08:04, 10 May 2007 (UTC).

Principle, theory, theorem, physical law, and hypothesis? Laws of science seems to be a good introduction as well. Nimur 08:25, 10 May 2007 (UTC)

Embalming and eyes question?

This is a bit morbid but I just want to know whether the eyeballs are removed for embalming and are the eyelids sewn or closed shut in some way like the mouth? I remember hearing somewhere that the eyelids are sewn shut to stop them 'popping' open during the viewing and that many years ago a penny would be placed on each eyelid for this reason. I don't know whether this was ever really done or whether it was instead a cultural/tradition thing but have always wondered about it and thought more about it recently when thinking about organ donation and the eyes were on the list. I'd appreciate any relevant answers or info, particularly from morticians/embalmers. Jocee 13:18, 10 May 2007 (UTC)

There are two methods that are widely used for keeping the eyes shut. The most common is the "eye cap", which is a bit like a contact lens with "grippers". It's placed under the eyelids, over the eyeballs, and keeps the lids in position. Another less-used technique is to glue the lids together. Eyeballs are not removed. Even if the corneas have been donated, it's just the corneas that are removed, not the entire eyeball. Coins on the eyes is a very old tradition, but usually explained religiously (e.g. payment for Charon's ferry) rather than practically. - Nunh-huh 13:36, 10 May 2007 (UTC)

I always assumed that the coins were placed on the eyes to assure that as rigor mortis set in, the eyelids were closed; if they were open at that time, it'd be impossible to fix until after the rigor had passed. ("He's not dead, he's just starin' at Wikipedia! Honest -- hold a mirror to his mouth!")

Atlant 16:34, 10 May 2007 (UTC)

The timing of rigor mortis makes it unlikely that this would be the reason unless the coins are placed there as soon as death occurs and would only be useful if the body is being displayed fairly shortly thereafter. Many people forget that rigor mortis is only a transient state. DMacks 16:54, 10 May 2007 (UTC)

According to our article, you've got 3-4 hours to get the coins on, else Aunt Bertha will be staring at you for the next 36 hours. And lots of people don't die by surprise, so application time often wasn't a factor.

Atlant 22:25, 10 May 2007 (UTC)

Freezing Points

Hello, My question is: What is the freezing point of a 25mM sodium bicarbonate solution? —The preceding unsigned comment was added by 208.38.54.242 (talk) 15:28, 10 May 2007 (UTC).

See our article about freezing point depression to learn how to calculate this. DMacks 16:15, 10 May 2007 (UTC)

Why elliptical orbits?

This is not an assignment, it is simply a discussion. My teacher suggested that I post it here. We were wondering why planets travel in an elliptical orbit? Why not just a circle? What is the other focal point? We haven't found it anywhere, but we're looking. Thanks for any insight you can give us! Someone999456 17:43, 10 May 2007 (UTC)

Hmm, tough one. I can't answer your question outright, but I suggest you take a look at Kepler's laws of planetary motion Aiyda 18:26, 10 May 2007 (UTC)

Our orbit article says that there is "nothing present at the other focus." --LarryMac | Talk 18:27, 10 May 2007 (UTC)

Orbits can be perfectly (or very nearly) circular, but it takes some very precise starting conditions - given the immense number of "non-circular" orbits compared with the (technically one) truly circular orbit, its no surprise that most orbits seen are elliptical, as a matter of probability. As for what is present at the other focus of the ellipse - as far as I'm aware, this has no real physical meaning, and is just an artifact of the mathematical description - someone please, correct me if I'm wrong. Of course you could say it's the point at which the orbit would be unchanged if the orbitted body was moved to it... Icthyos 18:30, 10 May 2007 (UTC)

The fish's last sentence is wrong because the speeds would be wrong. —Tamfang 02:00, 11 May 2007 (UTC)

(eC) Kepler's laws of planetary motion are just applications of the usual laws of nature involving moving objects (force, inertia, gravity, etc). In addition to that Kepler page, see also Orbit equation and Orbital mechanics for various levels of related mathematical and physics discussions. The simple answer for "why not a circle" is because as the Earth (for example) swings past the Sun (for example), it's moving too fast for gravity to slow it down and pull it back around in a circle (note that there are cases of circular orbits, but they are relatively rare; you can think of a circle as just a special case of an ellipse, one where the two focci are at the same point). There's nothing really "at" the other focal point per se. DMacks 18:31, 10 May 2007 (UTC)

A circle is a type of ellipse (where the minor axis equals the major axis and the two focus points coincide). Consider what would happen if all orbits started as circular. After that, any impact or gravitational tug from nearby planets or objects would perturb it into a non-circular elliptical orbit. StuRat 20:25, 10 May 2007 (UTC)

Another way to look at it is that an ellipse forms a perfectly stable orbit - with all of the forces on the planet in perfect balance the whole way around. There is simply no left-over force to pull the orbit into a circle...so from an energy perspective - it makes no difference whether your orbit is elliptical or perfectly circular. SteveBaker 21:06, 10 May 2007 (UTC)

This question seems somewhat similar to the oft-asked question "Why do the vast majority of planets spin on an axis?". There's absolutely no reason for them to not spin, or orbit elliptically, considering the effectively random conditions that they formed under. Circular orbits and no rotation are such incredibly precise conditions for a planet to have that it's almost impossible. 213.48.15.234 09:00, 11 May 2007 (UTC)

SteveBaker's suggestion that the forces are balanced in an elliptical orbit cannot be true - negating perturbations from other planets, there is only one force acting on the planet - from the Sun. It's all basically down to how much angular momentum the planet has. Angular momentum is constant throughout time for a planet - neglecting perturbations from other objects.

In an ellipse, near to perihelion, the planet has more angular momentum than a planet orbiting in a circle at that distance (so will begin to draw away from the sun). Near to aphelion, the planet has less angular momentum than a planet orbiting in a circle at that distance (so will begin to fall inwards towards the sun). Angular momentum increases with distance from the sun for planets in a circular orbit, i.e. Earth has much more angular momentum than Venus, despite similar mass and Venus travelling faster.

So it will not orbit in a perfect circle, unless it had the required angular momentum to match that for a circular orbit at that distance from the sun. As angular momentum for a circular orbit rises as distance from the Sun increases, an object which is getting further from the Sun soon falls behind on the required angular momentum (because its individual angular momentum is constant through time), so it falls back inwards into the solar system, where it suddenly gets ahead of its angular momentum requirement, so it rises back outwards from the Sun. It might have enough speed in the first place to escape completely, but that is another question.Richard B 13:49, 11 May 2007 (UTC)

life question

If the sun were to switch off instead of exploding and destroying the earth, would the bacteria that live in volcanoes and use sulpur as a source of energy, or the creatures that eat them, ever evolved into an inteligent, human-like specis? And would they be able to live outside of the volcanoes, somehow extracting sulphur from rocks? Apart from these, are there any other possible sources of energy that living organisms can use if there wasn't a star nearby? HS7 17:50, 10 May 2007 (UTC).

First of all, assuming that the outward pressure supplied by the sun's nuclear fusion is replaced in equal quantity (ie preventing the sun from collapsing on itself), then on a simplistic level, we wouldn't actually notice any difference - since the mean free path of the photon within the sun is so small (typically a few mm according to [[Sun#Core|the article]) the photons' "travel time" between being produced and reaching Earth is around a million years or so, though the lower limit given in the article is 17,000 years - we certainly wouldn't notice a lack of sunlight without our generation - Just an aside.

As for life continuing on without the light of the sun - I'm skeptical. Perhaps some xenobiologists could help out? Icthyos 18:25, 10 May 2007 (UTC)

I see no reason why life in, say, deep oceans wouldn't continue to exist for quite some time, as the sun has little to no energy input in those systems. Ecosystems surrounding black smokers would be one such example. However, evolving from that state to one of human-level intelligence is quite a stretch. — Lomn 20:03, 10 May 2007 (UTC)

Yeah - it's not that life up here on the surface is somehow preventing those creatures from evolving - it's that in their ecological niche - they are better off being how they are right now. Whilst there is energy to be had in those weird setups - it's pretty pathetic compared to sunlight - my guess is that they are using all the energy they can get just to be what they are now. It's a commonly held myth that all creatures evolve towards the pinnacle of intelligence and everything is moving steadily "up the evolutionary ladder". Evolution doesn't work that way - it works to provide the best match between the creature and it's environment. That can also mean evolving to be less sophisticated - smaller, weaker, slower or more stupid. When ordinary land creatures get stuck in a deep dark cave (where their eyes are useless) - they gradually evolve so as not to have eyes anymore. Whilst that seems like a setback for them - it's quite the opposite. By not spending the energy required to make and maintain eyes - and all of the brain to make use of them - the creature has more energy left over for reproduction - and that's all evolution "cares about". SteveBaker 21:03, 10 May 2007 (UTC)

Steve, are you sure that life up here couldn't, at least in principle, be impeding the evolution of those creatures? Sidestepping the practical question of survival of life without sunlight... if most life on earth were magically destroyed, wouldn't we expect to see adaptive radiation among the survivors? --Allen 03:12, 11 May 2007 (UTC)

I don't see how - they use completely different resources to creatures at the top of the water column and on land - it's hard to imagine what we could be doing to prevent them from evolving - they are trapped by their very weird life-styles. But you are certainly correct in saying that if we all magically disappeared one day, they would evolve to fill our niche - but that wasn't the question. The questioner specifies that all of the resources in the 'upper world' have vanished due to the abrupt loss of sunlight - so there is no resource for these creatures to evolve to take advantage of. Heat from the earth's core is the only remaining source of energy for them to extract. SteveBaker 03:30, 11 May 2007 (UTC)

You're right; I think I misunderstood the emphasis of what you had said. --Allen 03:49, 11 May 2007 (UTC)

There is evidence that there are no organisms or groups of organisms living on earth which are independent of the sun's energy for life, including the above-mentioned deep-sea vent communities. This was discussed (though consensus was not reached) on this reference desk in an article entitled "when the sun goes red giant" which was at least partially edited on September 27, 2006, I don't know how to link this conversation personally, but perhaps someone else could help me out. ^tucker/_rekcut 22:40, 10 May 2007 (UTC)

[I provided your link.] --Tardis 23:09, 10 May 2007 (UTC)

Shouldn't all life on the top of the planet cease to exist in such a contest? Wouldn't it be just a giant ice cube? Bastard Soap 13:26, 11 May 2007 (UTC)

old books

can anyone reccomend any places (in england) where I can find old books. I am looking for both books that were written a few decades ago and aren't available in bookshops any more, and for books written a few centuries ago. In particular I am interested in classical greek and roman books (translated into english).HS7 18:02, 10 May 2007 (UTC)

Try Book collecting. Some folks on the Talk page there may have an interest in the subject and can speak more for where to look for these things. You're probably going to be looking at eBay or finding small book collecting shops to do this. -- Kesh 18:44, 10 May 2007 (UTC)

As places, Hay-on-Wye or the Charing Cross Road in London are certainly the ones to go for. Johnbod 20:00, 10 May 2007 (UTC)

I suppose we need to know your location a bit more precisely if we are to recommend particular brick and mortar stores. For online bookstores, I believe Amazon.com also sells used, recent books. StuRat 20:06, 10 May 2007 (UTC)

I found Totnes almost as interesting as Hay-on-Wye. —Tamfang 01:58, 11 May 2007 (UTC)

Pollination

What types of bees did most of the pollinating in the Western Hemisphere before the importation of the European honeybee? Corvus cornix 18:06, 10 May 2007 (UTC)

In my little garden I see lots of different insects visiting the flowers. If you look close, there are manny different types of flies among them. 84.160.220.235 19:37, 10 May 2007 (UTC)

That's right, it's not just bees that pollinate flowers, and not just insects, either. Hummingbirds do their share, as well. StuRat 19:58, 10 May 2007 (UTC)

paper cut

After getting a papercut, how long should I expect it to take before I can't see it any more. I've had a cut on my finger for hours and there is still a faint orange line. And is paper cut one word or two? HS7 18:06, 10 May 2007 (UTC)

You shouldn't be worried!! If all there is after a couple of hours is a faint orange line, there is no problem what so ever. I would expect it to take 1-4 days to heal, but other factors can affect it. Someone999456 21:47, 10 May 2007 (UTC)

There are many factors in healing, including your age, the location and severity of the cut, whether it gets infected, whether it's wet or dry (cuts kept moist heal much faster), and so on. I once was reading in bed and when I turned the page, got a nasty paper cut on my eyeball. I thought I'd be suffering for a while, but by the next day it had totally healed, probably due to being kept moist. You may have noticed that small injuries in your mouth heal very quickly, too. Paper cuts on fingers usually take me 2-4 days to repair. Wound healing might have more information for you. --TotoBaggins 19:01, 10 May 2007 (UTC)

Seriously, on your eyeball? Ouch! Aiyda 19:43, 10 May 2007 (UTC)

One of my friends, the same thing happened to him, but he said not to worry about it because the eye is the fastest healing of all body tissues. Is that right? [Mac Δαvιs] ❖ 01:04, 11 May 2007 (UTC)

I once cut my finger about 3mm deep with a simple sheet of paper. It took weeks to heal. I suppose, with enough bad luck, a paper can cut all the flesh right to the bone. 84.160.220.235 19:05, 10 May 2007 (UTC)

One important factor is that the two sides of the cut should be held together. Normally this isn't an issue, but if the cut is on your hands and you are using them, the cut can be stretched apart from time to time, slowing the healing process. A bandage can help with this, but also can keep oxygen out, and oxygen promotes wound healing. StuRat 19:45, 10 May 2007 (UTC)

The cut I had was clean and smooth and nearly painless. A surgeon would have been proud of it. 84.160.220.235 20:53, 10 May 2007 (UTC)

Wound glue can be helpful with these "surgical-grade" paper cuts. ;-)

Atlant 12:17, 11 May 2007 (UTC)

I once cut my foot open on the disc draw of my DVD player. It hurt like all hell and was quite deep and long. Moral of the story? Don't operate your DVD player with your toes...

Nebuchandezzar 08:10, 11 May 2007 (UTC)

What's the difference between a pathogen and an antigen?

What's the difference between a pathogen and an antigen? Anchoress 19:01, 10 May 2007 (UTC)

A pathogen is a whole infecting organism alive that causes pathology and disease, whereas an antigen is merely a molecule that triggers an immune recognition and reaction. An antigen is never the whole infecting organism (virus or bacteria) but a molecule on the organism's surface that is recognised (a protein or glucoprotein). Hence one infecting bacteria may be recognised by several antigens on its surface, and a purified antigen may be given on its own as a non-infectious non-pathogenic vaccination to teach the immune system to recognise and deal with the real pathogen if ever encountered. David Ruben ^Talk 19:10, 10 May 2007 (UTC)

Cool, thank you very much for that answer. Anchoress 19:57, 10 May 2007 (UTC)

I wonder if a prion could be called both an antigen and a pathogen. --JWSchmidt 19:20, 10 May 2007 (UTC)

A protein based antigen is typically only a small piece of protein, and not the whole protein, so probably not. Someguy1221 21:53, 10 May 2007 (UTC)

Also, is there any evidence that prions provoke an immune response? Anchoress 15:00, 11 May 2007 (UTC)

According to Clearance and prevention of prion infection in cell culture by anti-PrP antibodies, antibodies to prion protein can be made by mice. see also. --JWSchmidt 19:54, 11 May 2007 (UTC)

Leaf (species) identification for Commons images

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I just uploaded two images to Commons, photos I took a while back at the Montreal Botanical Gardens. They're of some leaves of a particular plant which was either a small tree or a large bush. I'd like to name the species of the plant on the description page, but I have no idea what it is. If someone would identify it for me, I would be grateful, although this is low priority. Above are the two images in question (don't worry, they're GDFL/CC:SA-AT licensed). I would appreciate a reply through my user talk page if possible (use the t in my signature). Nihiltres^(t.c.s) 20:28, 10 May 2007 (UTC)

A Pawpaw trees perhaps? I would guess that it would be some member of the Annonaceae family. S.dedalus 01:29, 11 May 2007 (UTC)

Onion milk?

I just peeled away the first layer of two onions and both leaked some kind of white, watery liquid from the ends. Any idea what this might be? --84.137.28.204 20:43, 10 May 2007 (UTC)

The natural juices of the onion. Mmmm... Onion juice. Tasty! Dismas|^(talk) 20:47, 10 May 2007 (UTC)

Are you sure? I've never seen onions do this and I am kinda scared it might be poisonous. --84.137.28.204 20:53, 10 May 2007 (UTC)

Some varieties, or some ripenesses, do it; some don't. But yes, Dismas is right, it's perfectly normal, and not at all hazardous (other than to your eyes, of course! :-) ). --Steve Summit (talk) 21:11, 10 May 2007 (UTC)

Onions spoil fairly quickly, and when they do the liquid coming out is milky rather than clear. Granted, there may be onions for which the fluid is cloudier than others. Edison 23:53, 10 May 2007 (UTC)

I've cooked with such onions with no problem. Its actually rather common with the yellow onions I've bought, even the ones freshly bought from the store. I didn't even know that they were supposedly "spoiled". (Though I tend to cook them even if I see green stalks growing out.... if the bulb is brown though, it'd obviously be time to throw them out or maybe even replant.) Root⁴(one) 03:59, 11 May 2007 (UTC)

The liquid I've seen in the center of onions is clear. StuRat 03:36, 11 May 2007 (UTC)

Titration Question !

Is a titration in the lab a good way to determine the concentration of an acid or base? Thanks for any help! —The preceding unsigned comment was added by 76.188.176.32 (talk) 21:59, 10 May 2007 (UTC).

Yes. That one was easy :-) Someguy1221 22:00, 10 May 2007 (UTC)

Mhmm.. any reasons why???

Well, the point of an acid-bade titration is to determine what relative quantities of an acid and a base (one of known concentration, one of unknown concentration) achieve a certain pH (indicated by a change in color of the indicator chemical you're using, usually phenolphthalein). Practically, it's the easiest and most error free way to directly measure the concentration of an acid/base without using an actual pH meter (that I know of). Someguy1221 22:10, 10 May 2007 (UTC)

Technically, titration could even be seen as more accurate than using a pH/ion electrode since electrochemical measuring devices actually quantify the ionic activity—which can be affected by temperature, concentration, etc. -- MarcoTolo 23:17, 10 May 2007 (UTC)

Climate /United States/lowest rainfall

What is the place and amount of the lowest average rainfall? —The preceding unsigned comment was added by 71.143.16.157 (talk) 23:02, 10 May 2007 (UTC).

The nation’s driest area is the Desert Southwest, specifically southwestern Arizona, southern Nevada and southeastern California. The average annual rainfall across most of the region is less than 5 inches per year. This area includes the driest large city in the USA – Yuma, Ariz., which receives just less than 3 inches annually. — Preceding unsigned comment added by 76.188.176.32 (talk • contribs) 23:31, 10 May 2007 (UTC)

And Death Valley gets less than 2 inches of rain per year. StuRat 03:34, 11 May 2007 (UTC)

Titration

This is a continuation of a previous asked question ..

Are there any limitations to the titration method? What are they? —The preceding unsigned comment was added by 76.188.176.32 (talk) 23:25, 10 May 2007 (UTC).

Yes. The titration method cannot readily be used to make a planet-eating robot, to name but one. Can you be a little more specific about what kinds of limitations you're looking for? Algebraist 11:17, 11 May 2007 (UTC)

Going back to my high school and college chem classes many years ago, an obvious limitation is that the user must make a subjective determination of whe he has dripped enough of a reagant into the solution to cause a color change, which has an inherent subjectivity. The process is repeated with the two sources and the amounts noted, to use statistical averaging to achieve a more precise number. Edison 13:18, 11 May 2007 (UTC)

May 11

Vascular bundles

I understood from the monocotyledon article that vascular bundles are randomly interspersed in monocotyledons and annularly arranged in dicotyledons, but how are they arranged in the stems of woody plants? Thanks, anon. —The preceding unsigned comment was added by 162.83.152.149 (talk) 01:38, 11 May 2007 (UTC).

Try vascular cambium and cork cambium as a starting point. David D. (Talk) 03:56, 11 May 2007 (UTC)

drug names

Where do drug names come from? One expects brand names to be arbitrary, but the generic names also seem to have very little in the way of etymology, as if the syllables were chosen like Bingo numbers. —Tamfang 02:04, 11 May 2007 (UTC)

See the International Nonproprietary Name page. DMacks 02:26, 11 May 2007 (UTC)

That article tells me only that an authority exists; nothing about its principles or its procedures. (Compare planetary nomenclature.) Is a name proposed by the developer, or does the developer ask the INN authority to pull some syllables out of a hat? Does the IUPAC name (which has less apparent freedom) come first, and if so does the INN tend to reflect it somehow? —Tamfang 04:46, 11 May 2007 (UTC)

It uses syllables from the "INN stems and modifiers from the WHO" document listed in the External links. That thing is almost 200 pages of fairly detailed and specific meanings for each syllable, not really amenable to a short list in the wiki article. DMacks 05:43, 11 May 2007 (UTC)

Bioethics and astrobiology

From what I understand, most people think it's perfectly ethical to use animals for academic purposes-- capture the animals, study their behaviour in a controlled environment, disect them, other expirements that may involved killing the animal, etc, so long as you don't cause unnecessary suffering or do really cruel things (definions of that vary greatly, but anyway). Ok what my question is, would it be the same for life on other planets? Obviously it would be okay for microbial life, and plant-like things if we find any. What about animals (or animal-like beings, aliens whatever)? On earth, we kinda think we're superior to animals, and human life much is more precious probably because of the enormous intelligence gap between us and the next most intelligent animals (apes, monkeys, dogs?). What about on other planets. Let's say we found a planet that resembles ours: millions of different species with one intelligent, dominant (perhaps civilized) one. Would we treat that one as an equall to us or just like any animal? Afterall, if aliens landed on earth and decided to study organisms, we would expect them to treat us different than the rest of the animals, right? (For example, we would be outraged if they rounded up a village of people and took them back home to study, but maybe not so much if they took a school of fish or something.) 209.53.181.150 03:17, 11 May 2007 (UTC)

I would think the same rules for deciding which animals get which protections would apply. It might be a bit more difficult to decide which alien animals are intelligent, though, if they are very different from us. For example, a creature which lives for a million years and has one thought a year might appear to us to be unintelligent. StuRat 03:31, 11 May 2007 (UTC)

"Perhaps, on alien worlds, we will be the ones bringing the anal probes." StuRat 03:31, 11 May 2007 (UTC)

Are you asking for an ethical principle or for a prediction of what's likely to happen? Either one is, I think, inappropriate here. —Tamfang 04:38, 11 May 2007 (UTC)

H Tristram Engelhardt has a book called "The Foundations of Bioethics" out there. He writes about creating a distinction between "person" and "human" for ethical purposes. He discusses criteria for persons, those who ethically cannot be experimented upon, and nonpersons, those that can. Check it out, I'll scan a few pages in for you or type in some quotes if you're interested. It's pretty heavy reading. [Mac Δαvιs] ❖ 07:19, 11 May 2007 (UTC)

Google Books has it here. --TotoBaggins 13:59, 11 May 2007 (UTC)

Nice find; I don't remember "Christian" being in it though. [Mac Δαvιs] ❖ 18:53, 11 May 2007 (UTC)

Dang, you're right, they're totally separate books. You can browse the, er, secular one here. --TotoBaggins 20:32, 11 May 2007 (UTC)

If aliens smarter than us by the same amount as we are smarter than chimps landed here and rounded us up by the village-load for dissection, our opinions on the topic would matter about as much as the opinions of the chimps matter when we do such things to them. --TotoBaggins 13:59, 11 May 2007 (UTC)

Alzeimer's Disease

I read in an article that Insulin can spur Alzeimers Disease. What if the patient is a diabetic??? Would it effect them neurologicaly? Would it effect thier motor skills???

TamaraDissa 05:01, 11 May 2007 (UTC)

A quick google search seems to say that Alzheimer's disease causes a drop in insulin or something, I am not a medical practitioner. Splintercellguy 06:37, 11 May 2007 (UTC)

EyeBrow Growth

Hypothetically speaking, If removed by using a blade, Will they grow back but to a slightly shorter length, slightly longer length, or no discernable difference in length? Its just i lost half an eyebrow in an accident and i really liked them incase you were wondering about such a bizzare question.

Thankyou. Weoyreb321 07:20, 11 May 2007 (UTC)

Assuming they were just cut, and there was no damage to the follicles, your eyebrows should grow back good as new same as before eventually. Just remember, not all follicles are growing at any given time, so it will be slightly thinner until all come back. Czmtzc 13:53, 11 May 2007 (UTC)

Note also that it's a myth that shaving causes hair to grow back coarser or thicker than it was previously. It can just seem like it since short hairs are stubby and stiff. --TotoBaggins 14:04, 11 May 2007 (UTC)

Vaporisation of Sweat

I was asked an interesting question in a heating and cooling test, and I'd like to be able to either justify my answer or understand why it was wrong by the time I talk to my teacher next. If a person's body gains 300J of heat every second while running a marathon, how much sweat must be produced in order for the body to remain at a constant temperature, ignoring heat loss by means other than perspiration? The question also gives a value for the latent heat of vaporisation of sweat, although I forgot what it was. I assumed that the average body temperature is 310K (although it is probably closer to 309.6K) and that the specific heat capacity of sweat is very close to that of water. Given this, should my formula for the amount of sweat needed to absorb 300J of heat contain the energy required for the water to heat from 310K to 373K, or should it just contain the energy required to vaporise the unkown mass of sweat? Or is there something else I'm forgetting entirely? Any help in understanding this question would be appreciated :) Vvitor 08:22, 11 May 2007 (UTC)

You know how when you're running a marathon, you don't writhe in agony? That's because the sweat on your body does not get heated to 373K before it evaporates. I would guess you're expected to assume that sweat evaporates at body temperature (don't know how true this is, but it's probably pretty close). So you're presumably meant to only count the latent heat of evaporation of sweat, which is probably close to that of water, giving about 0.13g of sweat a second. However, none of this matters much, since the energy required to evaporate is so much greater than that required to heat (about 260J to heat 1g by 63K). Algebraist 11:11, 11 May 2007 (UTC)

Bah! I feel like such an idiot! That makes sense, many thanks. If you have the time, though, could you please tell me if the question was correct in listing the "specific heat of vaporisation of sweat" and if a similar formula to boiling (mass x latent heat) would be used? This concept of a latent heat of evaporation is new to me. Thanks again! Vvitor 11:37, 11 May 2007 (UTC)

According to Standard enthalpy change of vaporization (latent heat is out of fashion, it seems), the energy involved depends on temperature but the dependence is so small it's generally ignored. Thus using the standard value and the standard formula seems good enough. Algebraist 15:01, 11 May 2007 (UTC)

Intelligent Dinosaurs

Human beings have been around for thousands of years and we evolved to intelligent beings. Dinosaurs had been around for millions of years. Is it possible (or any evidence) that an intelligent race evolved from the dinosaurs? If so, do you think that they probably left the planet? --Juliet 13:01, 11 May 2007 (UTC)

Well, scorpions and dragonflies have been around for a longer time yet, and still they never built a decent spacecraft ;) . Seriously, being around for a longer time impoves neither intelligence nor dexterity of a species, generally speaking. As for having left the Earth - I wouldn't subscribe to that point of view, unless presented with a very, very compelling piece of evidence. Cheers, Dr_Dima.

If our current thinking is correct, it's likely that modern birds are evolved from dinosaurs. African Grey Parrots haven't left the planet yet, but once they acquire a complete, developed system of language from humans, I'd watch out...

Atlant 13:28, 11 May 2007 (UTC)

I read about intelligent dinos somewhere but I don't remember where. Does anyone have a link to it? --Juliet 13:28, 11 May 2007 (UTC)

Evolution isn't teleological — it doesn't necessarily lead towards big brains at all, in fact most species do not require them and never even began to evolve them (think about how successful insects are even though they are pretty dumb). Dinosaurs evolved into thousands if not millions of species, all working within their evolutinary niches. They evolved flight, they evolved great size and small size, they evolved all manners of spikes and armor and the like. They, nor too many other species, evolved much intelligence. Most of them never bothered to evolve much of a forebrain, a necessary prerequisite. So there's no reason to think an intelligent race would have evolved from dinosaurs. Additionally any intelligent race with the abiilty for space travel would have left behind ample signs of this ability, if not in intelligently built structures, then likely in the record of their resource consumption (we'd find empty oil wells, evidence of ancient uranium mines, etc.). So no. --24.147.86.187 13:32, 11 May 2007 (UTC)

Evolution ... doesn't necessarily lead towards big brains at all. Indeed, our big brains will likely cause us to be selected against as a species. Does anyone really think humanity will fail to kill itself for as long as the scorpions and dragonflies have been around? So long as we don't do it by something like creating a laboratory black hole that doesn't immediately evaporate, I think big brains will just be an interesting evolutionary dead-end, not nearly as successful as a great set of wings or a really rad stinger. --TotoBaggins 14:17, 11 May 2007 (UTC)

Even so, 24, wouldn't all of that evidence rotted or decayed away? Also, I thought that Velociraptors and other types of raptors were intelligent? Isn't possible that they could have evolved into something greater?

Sure, and maybe they still will, if the aforementioned grey parrots ever get their act together, but there is no evidence that dinosaurs lived in cities or had nuclear reactors or aircraft carriers or even manhole covers. All of these things would be preserved at least as well as simple bones. FWIW, here's a paleontologist's *very* speculative view of what an intelligent saurian might look like: Troodon#The "Dinosauroid" --TotoBaggins 14:31, 11 May 2007 (UTC)

I think you're right that the most intelligent dinosaurs were Deinonychus and its relatives (judging from brain and body masses).

An interesting thought experiment: What would a fossilized car look like? The steel would oxidize, but the glass would probably only lose its organic components (AFAIK car windows are made of layers of glass and some synthetic material between them). Would the platinum catalyst survive?

I think from an intelligent species with an industrial civilization one would expect to find at least some durable metal alloys.

A thought about intelligence: Intelligence is hard to define. If you come up with a rigorous definition of intelligence - or if you say that IQ tests measure intelligence - most people will probably disagree and say that your definition does not include all aspects of intelligence. So to a certain degree we don't even know what we are talking about. What would constitute a "superhuman" intelligence?

That Dinosauroid looks like an alien that everyone describes as one should look like. Perhaps all aliens that are visiting/probing humans are Dinosauroids! --Juliet 14:36, 11 May 2007 (UTC)

Even if the dinos had an incredibly advanced civilization, more advanced than our own, all evidence would have been wiped out millions of years ago when Xenu dropped H-bombs all over the earth. Don't you guys pay any attention to L. Ron Hubbard? Someguy1221 16:04, 11 May 2007 (UTC)

Kidney donor?

Is it legal in Canada or other countries for a person to sell their kidney to somebody who needs it? Kidney_transplantation didn't have much.--Sonjaaa 13:39, 11 May 2007 (UTC)

In the UK the Human Tissue Act (and specifically this section) makes it an offence to "[offer] to supply any controlled material for reward", as this man just found out. — Matt Eason ^{(Talk • Contribs)} 14:31, 11 May 2007 (UTC)

It's not legal in the US either, although there are some doctors who want it to be in order to prevent a black market developing. You might find this New York Times article interesting. --TotoBaggins 14:33, 11 May 2007 (UTC)

In the US, selling of your (or anyone else's) organs is illegal, as TotoBaggins noted, per the Uniform Anatomical Gift Act. It does appear to be legal in Iran, according to the Transplant#Compensated_donation article (with sources, even). -- MarcoTolo 20:09, 11 May 2007 (UTC)

artificial symbiosis

how can we induce artificial symbiotic relationship between two microorganisms,knowing their genome.can you please tell me the actual sceintific process. —The preceding unsigned comment was added by 220.225.77.230 (talk) 14:39, 11 May 2007 (UTC).

I'm sorry, but what kind of symbiosis are you referring to? There are quite a few different ways for organisms to be in symbiosis. Have you looked at its article by chance? Someguy1221 15:59, 11 May 2007 (UTC)

Well, you could knock out the ability of one microorganism to make an amino acid, say Alanine. In another organism you knock out the ability to make a different amino acid say Lysine. Now neither of the organisms can survive independently with out a source of the protein that it is unable to synthesize itself, but together they could live symbiotically off of each other. --Czmtzc 19:45, 11 May 2007 (UTC)

I will give you a million dollars if you can get two bacterial colonies to sign a trade agreement ;-) Someguy1221 20:49, 11 May 2007 (UTC)

Body acts as a wireless radio antenna

I've got a little shower radio whose coated wire antenna snapped off a while ago. Now when I turn it on the output is mostly noise, but when I put my hand within about four inches of it the signal becomes crystal-clear - I don't even have to be touching the metal where the antenna snapped. Why? — Matt Eason ^{(Talk • Contribs)} 14:59, 11 May 2007 (UTC)

I guess (emphasis on "guess") that your hand and some conducting parts inside the radio form a capacitor which allows the high-frequency current to flow without you touching the radio. Then your body works as an antenna. Cheers, Dr_Dima.

Your body definitely interacts with and somewhat channels EM radiation. I don't know if there's a very simple mechanism for explaining what you observed, though. -- mattb 15:59, 11 May 2007 (UTC)

Compact fluorescent lamps

According to compact fluorescent lamp, the length of their life is dependent upon, among other factors, "frequency of cycling on and off". I am trying to find out just how significant this is. I know it is significant in old style fluorescent tubes that use a starter. Does this mean I should leave, say, a CFL in a hallway on for most of the evening to maximize its life? Obviously I don't want to leave it on for too long, otherwise I don't save any energy.--Shantavira 15:23, 11 May 2007 (UTC)

No, you shouldn't leave it on. here is the best source I can find on this. --Allen 15:58, 11 May 2007 (UTC)

"...so if you turn your fluorescent lamp off and on more frequently than every 5 seconds, you will use more power than normal." Very interesting. A myth exploded. Thank you.--Shantavira 18:06, 11 May 2007 (UTC)

Gaslighting

What is the evolutionary purpose behind gaslighting? I just got gaslighted at work (very successfully, btw), and after reading the article, I recall several times I have gaslighted friends or have been the victum of gaslighting, in particuar I've always felt a *strong* compelling desire to gaslight people. Is there some reason we seek to test/improve our ablity to manipulate others, or is it perhaps a way of putting someone in a position of uncertanity? XM 15:42, 11 May 2007 (UTC)

I would differentiate between cases where the perpetrator admits to the deception ("I was just playing with you"), which seems to be a type of joke, versus cases where no admission ever comes, which seems to be more a type of abuse aimed at increasing the perps power relative to the victim, by making the victim unsure of himself/herself. StuRat 18:36, 11 May 2007 (UTC)

Eggplant IQ

I heard a rumor that the eggplant has an IQ of 3, and since I am a vegetarian that really freaks me out. What is the real IQ of an eggplant? —The preceding unsigned comment was added by 66.92.72.238 (talk) 18:22, 11 May 2007 (UTC).

Eggplants do not have IQs - as they would not be able to take an IQ test to obtain a score. --Ali 18:27, 11 May 2007 (UTC)

Yes, it is most likely just a rumor. Once I asked from a professor studying the human brain what the meaning of the IQ associated to plants, animals, computers is (as found on some nice graphics in some newspapers). He replied that it is all nonsense. The IQ is calculated specifically based on the average human intelligence, so not only is it impossible to calculate on, for example, animals; it gets very inaccurate in the case of outstandingly intelligent/unintelligent people. --V. Szabolcs 18:41, 11 May 2007 (UTC)

I suppose it means that plants are, actually alive and actually do have some small bit of intelligence. Vegetarians seem to treat them as almost, unalive. They seem to treat eating live plants as different from dead animals, yet eating animals is barbaric and plants is intelligent. [Mac Δαvιs] ❖ 18:51, 11 May 2007 (UTC)

I take it that was sarcasm. Plants do some things, like repositioning themselves in the sunlight, that, in animals, is often accomplished by intelligence (a cat finding a sunny patch to warm up, fur example). However, in plants, this type of thing is accomplished by different mechanism. StuRat 19:57, 11 May 2007 (UTC)

Plant behaviour follows similar basic mechanisms to animals with respect to interacting with the environment, sense, signal, respond. These mechanisms do not require intelligence although intelligence might improve the response. David D. (Talk) 20:16, 11 May 2007 (UTC)

Soap Bubbles

Can anybody tell me the effect of water temperature on soap bubble forming? As surface tension is a function of temperature and the higher the temperature the lower the surface tension. So, are the soap bubbles less stablized in hot water as the surface tension is lower? —The preceding unsigned comment was added by Lucia12321 (talk • contribs) 18:35, 11 May 2007 (UTC).

Another factor is that soap bubbles tend to evaporate and pop rapidly in dry air, and temperature affects humidity. I'm not sure what the net effect is, however. StuRat 18:40, 11 May 2007 (UTC)

Astronomy : Black dwarf stars

It seems from information already in Wikipedia that white dwarfs take an exceptionally long time to cool into hypothetical black dwarfs. They cool more slowly as time progresses, and the coolest known white dwarfs are about 3900 K. It also seems that not enough time has passed for any stars in the universe to have cooled enough to become black dwarfs. Therefore my question is: Exactly how many Gyr will it take for a white dwarf currently at 3900 K to reach thermal equilibrium with the space in which it sits (presumably single digits of K), and become a black dwarf? I know this can vary with the mass and elemental content, so if necessary just assume common values.

This is not homework, just personal curiosity. 70.171.11.122 21:32, 11 May 2007 (UTC)

According to NASA it takes tens to hundreds of billions of years. Someguy1221 21:40, 11 May 2007 (UTC)

I believe there was a mistaken assumption in your question, however, that temps must fall to below 10°K for it to stop emitting light. I believe dwarf stars will stop emitting significant amounts of light at much higher temps than that. StuRat 21:49, 11 May 2007 (UTC)