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January 5

Jet engines

How do jet engines provide thrust? The mass of the hot air leaving the rear must be the same as the mass of the cold air entering the front, so its not throwing away mass apart from the small amount of fuel used. Thanks 92.28.251.68 (talk) 01:03, 5 January 2011 (UTC)

See Jet engine#General physical principles. It doesn't really have much to do with the mass of the air. Dismas| 01:05, 5 January 2011 (UTC)

Simply, here is what happens. Large amounts of air are sucked into the engine. It is then compressed. At this point, fuel is injected. It bursts into flames, causing a small explosion. It is pressure, not mass, that drives the engine. --T H F S W (T · C · E) 02:40, 5 January 2011 (UTC)

I disagree with THFSW. The rate at which the mass of air leaves the engine is almost the same as the rate at which it enters the engine. However, the rate at which momentum leaves the engine is many times greater than the rate at which momentum enters the engine. This is because the exhaust gases leave through a propelling nozzle specially sized so the speed of the exhaust is many times greater than the speed at which air enters the engine. Newton's 2nd Law of Motion can be expressed as the resultant force on a body is equal to the rate of change of the body's momentum. In the case of a jet engine, the rate of change of momentum of the air passing through the engine is very great and is equal to the thrust on the engine. See Turbojet#Net thrust.

If the propelling nozzle was inappropriately sized so that the exhaust left the engine at the same speed as air entered the engine there would be no surplus of momentum and no thrust on the engine. The pressure of the exhaust gas as it exits the propelling nozzle is usually about atmospheric, whereas the pressure of the air as it enters the engine is usually a bit higher than atmospheric so the pressure difference across the engine contributes drag, not thrust. That is why I disagree with THFSW. Dolphin (t) 02:57, 5 January 2011 (UTC)

(edit conflict) Our Airbreathing jet engine article says: "An airbreathing jet engine (or ducted jet engine) is a jet engine that has an inlet duct that admits air for the combustion of fuel in the air stream which forms a jet of hot gases used for propulsion. So thrust is provided by what is in effect a directionally controlled explosion (which our article says "is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases"). WikiDao ☯ 03:23, 5 January 2011 (UTC)

Yes, but if we view the entire engine as a black-box system (as the OP clearly does), the net effect that relatively slow air is ingested at the front of the engine and exits it at a much higher speed. The difference in speeds, times the mass of the air that streams through, is the thrust. The nozzle design serves to ensure that the exhaust jet is about at ambient pressure when it leaves the engine, such that as much as possible of the combustion energy contributes to thrust. –Henning Makholm (talk) 03:57, 5 January 2011 (UTC)

I'm sorry, but by "ambient pressure" do you mean to say that there is no jet blast? WikiDao ☯ 04:30, 5 January 2011 (UTC)

Jet blast is caused by the air's velocity. I think Makholm is saying that as much of the pressure is converted into velocity as possible before it leaves the engine. (After all, it doesn't help the airplane if the air expands 'sideways', which it could do if it were at high presure, but not constrained.) APL (talk) 05:27, 5 January 2011 (UTC)

Well, what I asked myself as a kid, and sometimes still do, is the following: A jet engine is basically a pipe with two sets of fans, one forcing air in at the front, one in the back, being driven by the exhaust and used to power the front fan. In between the two is the combustion chamber, where fuel is injected and burned, so that the gas rapidly heats and expands, causing an increase in pressure that escapes to the rear, providing thrust. Why is the pressurized hot gas not escaping both ways, front and back, thereby of course cutting off its own air supply and fizzle? I suspect it has something to do with both the shape of the "pipe", and the relative size and configuration of the fans, but I never found a satisfactory solution. It's even worse with ram jets, of course. Is is simply that the overpressure from the air speed is larger than the pressure in the burning chamber, and hence the hot gas has to escape to the back? --Stephan Schulz (talk) 13:53, 5 January 2011 (UTC)

Why is the pressurized hot gas not escaping both ways, front and back...? Before takeoff the fans have to start rotating in the right direction. This can be ensured by designing the intake and exhaust fans to have different efficiencies in competing as windmills. As long as they keep rotating, the jet engine produces thrust. Thrust is lost in the case of an abnormal Compressor stall. Ramjets are no good for takeoff because they don't work at all at zero air speed. Cuddlyable3 (talk) 16:29, 5 January 2011 (UTC)

I think the answer to Stephan's question is in the turbojet article: "As the mixture burns its temperature increases dramatically, but the pressure actually decreases a few percent. ... Some pressure drop is required, as it is the reason why the expanding gases travel out the rear of the engine rather than out the front." So the front of the turbine sees a slightly lower pressure than the rear of the compressor. But the temperature is higher at the turbine, so the volume of gas per time unit is larger through the turbine than through the compressor. Therefore the turbine does not need to extract all of the energy from the gas in order to drive the compressor; there is some left for thrust. –Henning Makholm (talk) 17:51, 5 January 2011 (UTC)

Chemical formulæ

What are the rules to identify how to properly write the chemical formula? — Preceding unsigned comment added by Sci-math-tech (talk • contribs) 08:46, 5 January 2011 (UTC)

title added by CS Miller (talk) 08:56, 5 January 2011 (UTC)

Revised title so as not to reflect one rule exclusively. Cuddlyable3 (talk) 15:59, 5 January 2011 (UTC)

Basically, there must be the same number of individual atoms on each side of the equation. If need be, you must have several of each molecule. For example

2 ( NH₃ ) + 3 ( O₂ ) → N₂ + 3 ( H₂O )

Here 2 molecules of ammonia, each containing 1 atom of nitrogen and 3 of hydrogen, react with 3 molecules of oxygen (each 2 atoms of oxygen) to form 1 molecule of nitrogen (2 atoms) and 3 molecules of water (each 2 hydrogen and 1 oxygen). CS Miller (talk) 08:56, 5 January 2011 (UTC)

How to write the formula of a given chemical? Or how to write the formula of a chemical reaction? Perhaps chemical formula or stoichiometry will be helpful to you. 206.116.252.164 (talk) 09:54, 5 January 2011 (UTC)

Formulae for chemical reactions should be in terms of element atoms using their standard abbreviations, as shown in the article Periodic table. Cuddlyable3 (talk) 16:01, 5 January 2011 (UTC)

How did the Big Bang escape its Schwartzschild radius?

When all the mass of the universe was once concentrated in a very small space, why didn't it collapse into a black hole? 93.132.167.177 (talk) 12:02, 5 January 2011 (UTC)

The initial outward exapansion of the big bang must have overwhelmed gravitational collapse. -Plasmic Physics (talk) 13:04, 5 January 2011 (UTC)

Not really my field of expertise, but the nature of the Big Bang's singularity is that it's the point where the math -- specifically, the math of general relativity (and therefore gravity) -- breaks down. GR doesn't claim to explain the initial moments of the BB, and speculation is that the forces involved in the Planck epoch simply may not be the ones we recognize today. As such, it may be that gravity didn't exist (or function) then as we understand it now. — Lomn 14:30, 5 January 2011 (UTC)

To avoid singularities or effects near singularities, look at the time 1 second after the BB. The mass cannot have progressed more than 2 light seconds and that should be much smaller than the Schwartzschild radius. 93.132.167.177 (talk) 15:05, 5 January 2011 (UTC)

The term "Schwarzschild radius" doesn't mean an awful lot in that context. Matter had a very high density 1 sec after the "Big Bang", but it filled the entire space homogeneously. Hence every particle was attracted equally in all directions, so effectively, it wasn't attracted at all. Expressed differently, there was no centre toward which the matter could have collapsed. Still, the effect of gravitation was there, of course, it slowed down the expansion. With sufficient matter (and no dark energy) it could have slowed down the expansion and the Universe could have recollapsed. As we know it hasn't done so yet, and as far as we know, it will not in the future. As a general rule I suggest never to start reasoning at the Big Bang — that's a singularity, or in any case a condition that we know little to nothing about, you cannot derive anything from that. Always start your reasoning at the present time, then go backwards. --Wrongfilter (talk) 15:42, 5 January 2011 (UTC)

(edit conflict) The point is that, in the time arbitrarily close to the big bang, our physics breaks down. Things like the mathematics used to explain black holes and event horizons and Schwartzchild radius and all that stuff is based on how the universe works today. We don't have effective tools to look at the big bang itself, so attempting to extrapolate a concept like Schwartzchild radius to the big bang doesn't hold up. --Jayron32 15:44, 5 January 2011 (UTC)

Because it was the inside not the outside of a black hole expanding? Cuddlyable3 (talk) 15:50, 5 January 2011 (UTC)

So then are we to assume that the laws of science we have today are invalid at some point arbitrarily close to the big bang? How long after the BB do we have to wait for the laws of science to become valid? Googlemeister (talk) 16:36, 5 January 2011 (UTC)

No bright line cut off, but physics from the end of the inflationary epoch, at about 10 seconds after the Big Bang, and onwards is well understood. The details of cosmic inflation, from about 10 seconds aBB to 10 seconds aBB, are somewhat speculative, and to go back earlier than 10 seconds aBB you need a Grand Unified Theory, for which we don't currently have an agreed model. Gandalf61 (talk) 16:49, 5 January 2011 (UTC)

(edit conflict) See Lomn's post above; we really don't know since General Relativity literally doesn't work under the conditions present during the very short time periods after the Big Bang. See also Timeline_of_the_Big_Bang#Planck_epoch and Planck epoch. There's lots of propositions, many of the conflicting, about what this time might have worked like. But we have nothing firm or reliable to work from. So, your statement, which seems a bit sarcastic, is actually spot on. Particularly relevent is the statement at Big_Bang#Timeline_of_the_Big_Bang, which says "How closely we can extrapolate towards the singularity is debated—certainly not earlier than the Planck epoch." There is some stuff we are pretty sure about; say everything from the inflationary epoch onward. Some stuff, like the Planck epoch, we're confidently clueless, and the stuff in between is progressively fuzzier the further we go back. --Jayron32 16:56, 5 January 2011 (UTC)

I agree with Wrongfilter and Cuddlyable3. There is no mystery here at all. As our Schwarzschild metric article says: "The Schwarzschild metric is a solution of Einstein's field equations in empty space, meaning that it is valid only outside the gravitating body". But at (or soon after) the Big Bang there was no "outside" - the whole universe was very homogenous and at approximately the same density, hence the assumptions behind the Schwarzschild metric and Schwarzschild radius do not hold. Gandalf61 (talk) 16:41, 5 January 2011 (UTC)

So what you are saying is that there could be more of a structure inside a black hole but the commonly believed singularity within which all the mass is concentrated? Is this just an ad hoc assumption or do you have any reference? 93.132.167.177 (talk) 18:22, 5 January 2011 (UTC)

Actually the answer is we don't know. The singularity is the simplest explanation, and works with current theories, but it is literally impossible to do any experiments, tests, or anything else to study it or confirm it. See Cosmic censorship hypothesis. --Jayron32 19:32, 5 January 2011 (UTC)

Another way to look at this is to think about a black hole. Nothing can escape because even light is sucked back in, and nothing can exceed the speed of light. But in the Big Bang nothing escaped - it is all still inside the "hole". And in the sense in which the universe does "expand", it can expand faster than the speed of light. This is an expansion of space, rather than a motion of everything through space. Wnt (talk) 19:37, 5 January 2011 (UTC)

I feel many of you got me wrong. I'm not speculating about singularities or extreme and unknown physics around them. As from the article, one second after BB is pretty a lot of time for physics to adjust to what we see now. The other point is that we (the universe) might be inside of a black hole but from what I have heard about black holes, everything inside is attracted to the central singularity (or the very proximity in case of unknown effects) in a finite (and, as I remember, small) amount of proper time. So either there is something substantially wrong with my understanding of Big Bang, and/or with my understanding of black holes, or I am missing a clue to conciliate what looks like a contradiction. As my original question is a quite simple and obvious one and I never heard that anyone asked that before I can only guess that the answer is so simple that no one who knows it bothers to tell. 93.132.167.177 (talk) 21:45, 5 January 2011 (UTC)

Where do people get the idea from that there might be a connection between the Big Bang and black holes? From what I know there is none. What is that even supposed to mean, "the universe might be inside of a black hole"? Mind, I don't blame you, this comes up in forums (from laypersons) again and again. --Wrongfilter (talk) 22:38, 5 January 2011 (UTC)

Well, that's easy enough: big mass concentrated in a small volume. But, ok, if you people here feel that everything outside your encyclopaedic universe is a crackpots thought ... well thank you all for your contributions so far but don't waste your time on that any more. 93.132.167.177 (talk) 23:24, 5 January 2011 (UTC)

There have been some pretty bad answers above. There is nothing mysterious about Big Bang plus one second. All the normal rules of physics apply. The problem is actually with the understanding of how black holes form. If you have an isolated mass that is more compact than a Schwarzschild radius then it will inevitably collapse into a black hole. However the "isolated" part is important. If you view gravity in terms of the "rubber sheet" analogy, then the isolated mass creates a depression so deep that nothing (not even light) has enough energy to climb out of. But what happens if you sprinkle mass uniformly across the sheet? Every part of the sheet is pressed down but no part forms a localized depression. Nothing has to expend energy climbing out of a hole, because there is nothing to identify a "hole" or an "outside", everything is the same. If you assume that the universe was uniformly filled with mass and has no boundary, then the Schwarzschild solution just doesn't apply. Predicting a collapse from the Schwarzschild radius relies on the ability to distinguish between a very massive region and an approximately massless region around it. In a homogeneous universe that contrast just doesn't exist. (The universe actually could still collapse into a singularity. This is the possible future that we refer to as the Big Crunch, but the mechanics of how this occurs are more nuanced than the simple Schwarzschild considerations.) Dragons flight (talk) 06:08, 6 January 2011 (UTC)

The rubber sheet model isn't a good model of GR, but yes, it's important to understand that the early expansion of the universe (including inflation!) is modeled by general relativity and not by some unknown pre-GR theory of gravity. There are theorems establishing certain conditions under which a black hole singularity must form, and the big bang doesn't satisfy those conditions. The conditions are more complicated than just a lot of mass concentrated in a small volume. A big bang universe that's above the cosmological "critical density" does satisfy the conditions for black hole collapse, and does (re)collapse (the big crunch).

There is a close connection between the big bang and black holes. The big bang resembles a time-reversed version of a (highly symmetric) black hole collapse. You can surround the whole visible universe by a Schwarzschild vacuum, putting everything "inside a black hole", without contradicting observations. -- BenRG (talk) 00:18, 8 January 2011 (UTC)

The point of the original question is that during the very early universe you can identify quite small volumes (even smaller than the size of the visible universe at that time) such that if taken in isolation they have sufficient mass to individually form black holes. Yes, the universe as a whole might be viewed as living inside a black hole, but that doesn't answer the original question of why primordial massive regions didn't collapse. The answer is that if the mass is homogeneous rather than isolated then the total implied curvature is insufficient to form an event horizon around those local massive regions. Dragons flight (talk) 14:43, 9 January 2011 (UTC)

The above discussion confuses me in one respect: it was my understanding that there was no matter up to and including the inflationary epoch (and a bit beyond) -- i.e., that the universe was "space" and only space. Did I mistakenly believe that I'd repeatedly read that? 63.17.67.25 (talk) 03:59, 8 January 2011 (UTC)

It's not what the what the inflationary hypothesis ordinarily says. During the inflationary period, space was certainly not empty. What you may have read is that the elementary particles of our current universe could not exist during inflation. But there would have been something else there instead -- weird and wonderful high-energy stuff that nobody can explain in detail given today's knowledge. The inflationary epoch ended when the weird stuff eventually "crystallized" into our current set of quarks, leptons and so forth. –Henning Makholm (talk) 04:14, 8 January 2011 (UTC)

I don't have all or even most of what I've read on hand. But here's one example (similar to others) from what I do have: "During this brief but critical period the universe was but a vacuum.... he cosmic vacuum remain empty even after falling below the temperature at which particle production ordinarily would take place." -- "Coming of Age in the Milky Way" by T. Ferris, pp. 358-59. 63.17.67.25 (talk) 04:35, 8 January 2011 (UTC)

The universe during the inflationary epoch is often modeled as a "Lambda vacuum". This has the word "vacuum" in it, and it's perfectly fine to think of it as a vacuum, and many physicists do think of it as a vacuum; but that doesn't mean quite what you might think. The GR field equation (ignoring some uninteresting constants) looks like G + Λg = T, where G is the "Einstein tensor" describing spacetime curvature, Λ is the "cosmological constant", g is the "metric tensor" describing... well... spacetime curvature again, I suppose, and T is the "stress-energy tensor" describing everything else (the other forces and the fermions). Inflation is described by a model with T zero and Λ nonzero. T=0 makes it a vacuum, by definition. However, you could just as well define T' = T − Λg and write the equation as G = T', with T' nonzero. T' includes the stuff that was in T plus something else represented by −Λg, and the extra thing turns out to behave like a spin-0 particle (=field) with a nonzero value everywhere (like the Higgs field). In point of fact, you need a particle with some kind of time-varying behavior in order for inflation to eventually end (Λ can't really be a constant), so this view is more accurate that the cosmological-constant view. Inflation ends when the background field decays into a mess of weird and wonderful high-energy stuff, which eventually turns into the low-energy particles that we're made of. -- BenRG (talk) 05:57, 8 January 2011 (UTC)

63.17.67.25 - I think you are confusing "matter" and "mass". There was no matter before the inflationary epoch (in the sense that the elementary particles that make up what we currently think of as matter did not exist) but there was certainly plenty of mass (or, if you prefer, plenty of energy). Gandalf61 (talk) 06:49, 8 January 2011 (UTC)

grueblers equation

relation between number of pairs and number of links as given by the L=2P-4.is it also named as the grueblers equation ..? there is one equation for degrees of freedom by gruebler.. is this also ... please help me .. —Preceding unsigned comment added by 59.93.130.246 (talk) 14:23, 5 January 2011 (UTC)

Your question is not at all clear to me, but you might find the information at Linkage_(mechanical)#Theory useful. AndrewWTaylor (talk) 14:45, 5 January 2011 (UTC)

I am asking that besides popularly known(F=3(n-1)-2f) can we name (l=2p-4,applies to kinematic chains) also as gruebler's equation. very simply can we call L=2p-4 as gruebler's equation. —Preceding unsigned comment added by 59.93.130.246 (talk) 14:59, 5 January 2011 (UTC)

Your popularly known equation is Kutzbach-Gruebler's equation. Misplaced Pages doesn't have an article about Arnulf Grübler but his Curriculum Vitae is online with an e-mail address so you could try asking his opinion. Cuddlyable3 (talk) 15:46, 5 January 2011 (UTC)

Color of food and nutritional value

Is the color of food related to its nutritional value? A certain Gillian_McKeith claims it is, however, she is a mixture of crackpot theories and common sense advice, so I don't know if she's right on this point.Quest09 (talk) 15:23, 5 January 2011 (UTC)

Certainly not in the modern world. Many foods have colors added to them that don't effect the nutritional value. Even some fruits and veggies have been selectively bred so that they don't have the same colors as their wild counterparts! (Carrots weren't originally orange, for example.) APL (talk) 15:34, 5 January 2011 (UTC)

It depends a bit on what you mean by "color". There's a rough rule of thumb that "white foods" tend to have less nutritional value (that is, they have less vitamins and minerals and fiber per calorie) than more colored foods; so one can consider "white bread" to be less nutritional on that metric than whole-grain bread, and "white rice" as less nutritional than brown rice. Also, some nutrients are known for bright colors; lycopene is associated with tomatoes and other red foods, beta carotene with orange carrots, the so-called "green-leafy vegetables" like spinach and collards carry more nutritional value than the less strongly colored ones like iceberg lettuce. However, it only goes so far; white-meat chicken is lower in fat than say, more brightly colored steak. Using color as a metric to help remember which foods are more nutritious and healthier for you may be helpful, but it probably isn't the color itself which is the key factor. After all, if it were, wouldn't artificially colored foods be just as healthy as brightly colored vegetables? --Jayron32 15:39, 5 January 2011 (UTC)

I suppose that she meant raw food. Processed food can certainly have (almost?) any color you want.Quest09 (talk) 15:44, 5 January 2011 (UTC)

Well in the same vein as APL above, with modern biotechnology raw food probably can almost as well if you really want to. Nil Einne (talk) 16:10, 5 January 2011 (UTC)

Yes, you both are right on this. Food color can be manipulated. Salmon from fish-factories, for example, has its color due to what it was feed to. It's appealing salmon color is not that prevalent in nature. Quest09 (talk) 17:21, 5 January 2011 (UTC)

I'd never heard of the food-colour strategy in such a broad sense as that. I've only heard that rule of thumb applied to fruits, particularly berries. Our article on berries touches on this, but notes that the effect may not be that great. That being said, it's hard to argue with any rule of thumb that encourages eating a diversity of foods; that will almost always turn out to be more nutritious than eating a more limited diet. Matt Deres (talk) 16:06, 6 January 2011 (UTC)

Keep in mind that Gillian McKeith has a really poor understanding of science. She claims ... (quote) Chlorophyll is "high in oxygen". And the darker leaves on plants are good for you, she explains, because they contain "chlorophyll - the 'blood' of the plant - which will really oxygenate your blood." ] -- JSBillings 20:12, 6 January 2011 (UTC)

Nutritional doesn't necessarly mean beneficial. Foods like ice cream, deep fried nacho-cheese flavored tortilla chips, and butter are all very nutrient-dense foods; the problem is the nutrients they are almost exclusively comprised of are fat and carbohydrates.

A six month old orange.

This is a bit of an odd question, but here goes. I keep dried fruit on my desk. Well, sometimes I don't eat an orange, and instead of rotting, it goes hard and shrivels. I have a three year old satsuma that is like a ping-pong ball now.

I had an orange. I let it dry for six months (the secret is to keep turning it, otherwise it rots). I colleague wanted to see what it was like, cut in half. So, I cut it in half, and to my surprise it was still juicy inside.

Here's the question. I was dared to drink the juice, and I did. It tasted a bit funky, but it didn't kill me. What has happened to the juice in the six months? Is it toxic? Is it safe to drink?

Thanks in advance,

Zzubnik (talk) 15:46, 5 January 2011 (UTC)

Just hazarding a guess based on the funky taste, but it might be possible that the juice inside the orange fermented. Note, though, that this is sheer speculation, and I'm not claiming that this is necessarily the correct answer to what happened. Ks0stm 16:01, 5 January 2011 (UTC)

(edit conflict)If the juice inside was protected by the peel (which I suspect it would have been) so that nothing could get inside to ferment it, I suspect it wouldn't be all that bad for you. Without yeasts or bacteria to turn the juice into alcohol or vinegar, I don't see that much could happen. There may be internal reactions within the juice that slowly change it, but keeping out air completely is a common method of preservation. Well-sealed and properly handled bottles of wine can last decades and still be drinkable. They do change over time, but they remain perfectly fine. Wine that is exposed to air goes rotten to the point of inedibility in much shorter time periods. The trick is, keeping it so the peel remains intact; even microscopic holes in the peel could let in cultures which could spoil the orange. So, I would probably count yourself "lucky" it wasn't bad; you could run the exact same experiment again and get a very different result. --Jayron32 16:03, 5 January 2011 (UTC)

We seem to be thinking the same means with opposite ends...I was thinking the sealing of the peel would block oxygen from getting in, creating the anaerobic environment needed for fermentation...but given my lack of knowledge in the area, I'll defer to your answer. Ks0stm 16:06, 5 January 2011 (UTC)

Well, if it is so sealed that oxygen cannot get in, then bacteria and yeast, many orders of larger than oxygen molecules, would ALSO not be able to get in. Furthermore, if there were bacteria present in an oxygen-poor environment, it would be REALLY bad, anaerobic bacteria are particularly nasty, bacteria that cause botulism are anaerobic. Fermentation is also an anaerobic process, see Fermentation (biochemistry), but it too usually requires cultures to be carefully controlled; you want the right yeasts and bacteria to be present, random stuff from the environment can be a hit-or-miss prospect when it comes to getting "good" fermentation versus a nasty mess. But in general, fermentation cannot go on without some little bacteria or yeast to do it. --Jayron32 16:12, 5 January 2011 (UTC)

But plants have an innate immune system. This (probably) stops the Clostridium botulinum from entering the orange whilst it is developing; after that, as long as the skin is intact, the bacterium can't enter it. CS Miller (talk) 18:46, 5 January 2011 (UTC)

That's kinda, exactly, my point. --Jayron32 19:25, 5 January 2011 (UTC)

Indeed it was. I should have read your earlier reply better before posting. CS Miller (talk) 23:51, 5 January 2011 (UTC)

An important factor here is that the oranges you buy in the store are invariably coated with wax. Unwaxed citrus fruit will dry out within a few days. The peel itself has strong antibiotic properties, unless it is punctured, and the wax helps even more. Looie496 (talk) 18:48, 5 January 2011 (UTC)

I don't think they are coated with wax, at least not here, in Detroit. I know the feel of wax on my hands, which I get when touching waxed fruit, and I don't get that feeling when peeling an orange. StuRat (talk) 19:27, 5 January 2011 (UTC)

Also, I'd expect the orange to be dessicated, so that the juice is rather concentrated. Did it taste like that ? StuRat (talk) 19:28, 5 January 2011 (UTC)

Hi guys, and thanks for all the replies! To answer the question, it did taste concentrated, but it also had a different taste that I didn't recognize. I presume this is just what happens to orange juice over time if it doesn't spill. Like with wine, the flavour changes over time. Zzubnik (talk) 08:43, 6 January 2011 (UTC)

Interesting. And I suddenly feel much better after having just eaten a two week old Clementine! 10draftsdeep (talk) 14:41, 6 January 2011 (UTC)

Dog Knot

What is the puprose of the knot at the base of a dogs erect penis?

See here. --Sean 17:47, 5 January 2011 (UTC)

I think you mean see here. Cuddlyable3 (talk) 22:01, 5 January 2011 (UTC)

Nope. --Sean 22:34, 5 January 2011 (UTC)

Dark side

Does Uranus ahave a dark side? — Preceding unsigned comment added by BenYorkie (talk • contribs) 17:17, 5 January 2011 (UTC)

Yes, the one where the sun don't shine. See night. --Sean 17:44, 5 January 2011 (UTC)

No. All parts of Uranus receive direct sunlight at some point, so there is no permanent "dark side". However, due to Uranus's unusual axial tilt and 84-year orbit, some parts of the planet can spend extended periods in the dark. See Uranus#Orbit and rotation, where it states: "Each pole gets around 42 years of continuous sunlight, followed by 42 years of darkness". Karenjc 18:03, 5 January 2011 (UTC)

It's exactly analogous to the Midnight sun in the polar regions on Earth. The only difference is that Uranus has much larger polar regions (due to the extreme tilt), comprising nearly the entire planet, and that the Uranian year is much longer than a terrestrial year. Buddy431 (talk) 01:45, 6 January 2011 (UTC)

Okay, we've had "yes" and "no"; I'll add that the sunlight at that distance is so weak — under 1/300 of the amount we get here — that you could say it's all dark. --Anonymous, 19:01 UTC, January 5, 2010.

Eh, that'd be plenty of light for reading (it's substantially more than a full moon on Earth), so I don't think "all dark" holds up. — Lomn 19:34, 5 January 2011 (UTC)

Depends on how many clouds you have above you, since as a gas giant there really isn't a surface you can stand on, thus the point chosen is pretty arbitrary. Googlemeister (talk) 19:36, 5 January 2011 (UTC)

Wine Grape variety abreviations

Is there a universal Vitis vinifera grape variety abreviation list? —Preceding unsigned comment added by 200.6.100.224 (talk) 19:13, 5 January 2011 (UTC)

See List of grape varieties. --Jayron32 19:23, 5 January 2011 (UTC)

The OP is asking for a list of abbreviations - which are not in our article. Some of them are in this list, but it is not exhaustive. SpinningSpark 02:50, 6 January 2011 (UTC)

Soap making

I have been making my own bar soap .what chemicals can i add to the soap to improve the quality ? —Preceding unsigned comment added by 41.221.209.6 (talk) 19:57, 5 January 2011 (UTC)

Soap#Traditional_soap_making has an overview of homebrew soap making, as well as some ingredients and methods to alter the finished product. --Jayron32 20:00, 5 January 2011 (UTC)

I would like to recommend you look at glycerine soap which can be made by unskilled children without toxic or corrosive chemicals. But you should really ask Lisa Chouinard here because she does more fantastic stuff with soap than anyone I know. 71.198.176.22 (talk) 16:55, 8 January 2011 (UTC)

Miracle Mineral Supplement

Where can I get this? --98.221.179.18 (talk) 21:13, 5 January 2011 (UTC)

You don't want to. Seriously. Read the article. You have no use for it. --Jayron32 21:17, 5 January 2011 (UTC)

The claims made on the "official website" clearly fall within the realm of jurisdiction of the FDA - and in fact, has drawn legal and regulatory attention. The product is being illegally marketed as a drug without passing regulatory and safety requirements, according to the F.D.A. - so not only this substance highly toxic and hazardous, it is also against the law to sell or purchase it for medical use in the United States. Nimur (talk) 21:30, 5 January 2011 (UTC)

It's a total fraud, i did a lot of investigating into this because a close relative of mine got their hands on some about a year ago. This is a site which has some good information about this fraud.Vespine (talk) 21:48, 5 January 2011 (UTC)

(edit conflict)I was looking forward to getting some chlorine dioxide and/or sodium chlorite (for chemistry experiments). At least to get some pictures for Misplaced Pages. Of course I wouldn't drink it any more than I would drink bleach! --98.221.179.18 (talk) 21:49, 5 January 2011 (UTC)

(ec)(ec) The book by Miracle Mineral Solution's promoter Jim Humble states "I have provided complete details on how to make the solution in your kitchen, and to buy most of the ingredients off the shelf". Sale of the MMS concoction for any medical purpose whatever is judged illegal and dangerous. Its ingredient Sodium chlorite is a toxic oxidant of which 1 gram causes sickness and 10-15 grams death. The only positive medical advice we can give is that it is healthy to take reasonable doses of the compound dihydrogen monoxide in pure form. Cuddlyable3 (talk) 21:51, 5 January 2011 (UTC)

The book's author also links to this excellent example of a Medicare scam - a phony "cancer screening test kit." "While we do not work directly with private insurers, HMOs, or PPO plans, we can provide you with a receipt which you may be able to use to get reimbursement from your provider." Sadly, they probably have been successfully billing the Government for numerous sham tests. Let's hope the Feds swoop in on the whole operation quickly. Nimur (talk) 21:53, 5 January 2011 (UTC)

If you are after sodium chlorite fir experiments, just get some water purification tablets from a camping store. Vespine (talk) 22:08, 5 January 2011 (UTC)

Searching "Miracle Mineral Solution" in Google will net many places willing to ship the solution to you for a hefty price. Some of the places even appear to have brick and mortar stores as well. As a random example, "Moon's Light Magic" appears willing to ship you the stuff, and also appears to have a physical store in Roselle, Illinois. If you could be more specific in where you are, we could help you find a store that's closer. Buddy431 (talk) 23:40, 5 January 2011 (UTC)

Under 3 dollars, of course, or I wouldn't want it. That would probably rule out everything. --Chemicalinterest (talk) 23:44, 5 January 2011 (UTC)

I think Buddy431's reply is inappropriate for the science ref desk! Regardless of what the op claims he wants it for, this IS a question of medical claims and dangerously false ones at that. I strongly disagree with promoting or even linking to sites which sell this snake oil. Vespine (talk) 00:27, 6 January 2011 (UTC)

Why do you have a prejudice against a sodium chlorite solution? --Chemicalinterest (talk) 11:42, 6 January 2011 (UTC)

It's in deciding what is and isn't appropriate treatment that we are dispensing medical advice. Providing a link to a specific treatment that is asked for, whatever we think about the appropriateness of it, is not medical advice. Buddy431 (talk) 01:42, 6 January 2011 (UTC)

I've looked too deeply into this fraud to agree, spend a few minutes googling Jim Humble and if you are not flabbergasted by the blatant fraud and disinformation this guy spreads I'll be very surprised. Have a look at the google site i linked above. If you had said: "you can get homeopathy from here" you could argue that you're just giving information and leaving the choice to the individual, we could have an argument about scientific proof and what harm it can do and whatever, but MMS is a FRAUD, full stop, and it has been proven to be dangerous and is now illegal in several countries. It's definitely not just harmless woo woo. What you are doing is not just "giving information"; by linking sites involved in this scam you are in effect promoting for them, whether you do it inadvertently or not is beside the point IMHO. I still believe it's still inappropriate for the science ref desk. Vespine (talk) 02:05, 6 January 2011 (UTC)

The OP clearly says he wants it for chemical experiments, not as medicine. If he's lying, and takes the "supplement" as medicine despite all the warnings here, then he's an idiot and deserves whatever consequences result. --140.180.26.37 (talk) 07:48, 6 January 2011 (UTC)

Please note that User:Chemicalinterest is the same as User:98.221.179.18 (I memorized my IP). The only reason I am interested in this product is because it contains sodium chlorite; if I can find out how to make sodium chlorite from sodium chlorate without the explosive chlorine dioxide intermediate, then I will not ask for this product. --Chemicalinterest (talk) 11:43, 6 January 2011 (UTC)

Formula pronunciation

This formula appears in our proton-proton chain reaction article:

1H

+

1H

→

1D

+

e

+

ν e

+

0.42 MeV

Can someone tell me how that would be pronounced in English? Thanks. --Sean 22:33, 5 January 2011 (UTC)

One hydrogen atom fuses with another hydrogen atom, resulting in an atom of deuterium, a positron, an electron neutrino, and some extra energy. I mean, that's one way to do it. You could get more or less technical about it if you wanted to, e.g. describing the hydrogen as "hydrogen-one" and making clear how much energy there is (.42 million electron volts). You don't have to call deuterium anything other than deuterium (there is only one kind, by definition—I don't know why the formula links to "Deuterium-2", because deuterium has, by definition, a mass of 2). --Mr.98 (talk) 22:49, 5 January 2011 (UTC)

I think it is a priori ambiguous whether the notation
₁H
stands for neutral atoms or just the nuclei. Your suggestion picks the wrong interpretation (because then charge is not conserved across the reaction). –Henning Makholm (talk) 22:56, 5 January 2011 (UTC)

OK, that makes sense. I think specifying it as a bare proton probably is indeed most straightforward. --Mr.98 (talk) 23:24, 5 January 2011 (UTC)

(ec) "A proton and a proton become a deuterium nucleus, plus a positron, plus an electron neutrino, plus zero point four two megaelectronvolts"? –Henning Makholm (talk) 22:51, 5 January 2011 (UTC)

Going fully wordy: Hydrogen having 1 proton and one nucleon combines with hydrogen having 1 proton and one nucleon resulting in hydrogen having 1 proton and 2 nucleons (aka deuterium) plus a positively charged electron (aka positron) plus a neutrino of the electron type (aka electron neutrino) plus point four two Mega electron volts of energy. A lot of the more common particles have shorthand names, and
₁H
and
₁D
are the same thing - so you can write and say it either way. Ariel. (talk) 23:22, 5 January 2011 (UTC)

But that's not how you would actually pronounce the notation, is it? –Henning Makholm (talk) 00:20, 6 January 2011 (UTC)

Not for this, but by listing all the parameters it can help the OP generalize to other chains. Ariel. (talk) 00:53, 6 January 2011 (UTC)

I would be cautious about a potential ambiguity in that phrasing — the statement "hydrogen having 1 proton and one nucleon" can be readily and incorrectly misread as meaning that hydrogen nuclei contain one proton and one (other) nucleon. It might be clearer to go with something like "hydrogen, having 1 nucleon (a proton)..." or something in that vein. TenOfAllTrades(talk) 16:41, 6 January 2011 (UTC)

I'm not a physicist, so this is not an answer, but I think what the OP wants is a literal reading, as you would say when reading off the equation. Something like "one-hydrogen-one plus one-hydrogen-one yields one-deuterium-two plus electron-positive plus electron-neutrino plus zero-point-four-two em ee vee". But that's almost surely wrong - for example, I'm not sure exactly what order a physicist should read off the numbers or whether anyone would really say "electron-positive" rather than "positron" even when writing it on a blackboard. Wnt (talk) 18:51, 6 January 2011 (UTC)

Thanks to all. I was interested in both the minimal-ambiguity and colloquial readings, and they've been covered well, I think. --Sean 21:54, 6 January 2011 (UTC)

Plant food

I boil water on the stove as a method of humidifying my home. After a while of adding water and having it boil down, I end up with mineral-rich water that I need to dump to prevent it from depositing minerals on the pot. I was wondering, if, after I let it cool, of course, this would make good plant food. That is, would the mix of minerals in tap water be appropriate for your typical house plant ? StuRat (talk) 23:31, 5 January 2011 (UTC)

It's mostly calcium and magnesium (hard water), and they are listed as secondary macronutrients for plants. This and this don't mention any upper limit for them, but I didn't check any other sources. Ariel. (talk) 23:41, 5 January 2011 (UTC)

Edit: If you have a water softener then it's actually sodium and would be pretty bad for plants. Ariel. (talk) 00:04, 6 January 2011 (UTC)

Tap water composition depends a great deal on where you live. If your water company or municipality provides information about the tap water quality and composition, then you have a pretty good idea about what's left in your pot after boiling the water down. It is unlikely there will be a lot of potassium, phosphorus, and nitrogen, which is what plants need most; more likely you'll find a lot of calcium, magnesium, sodium, iron, chloride, and (bi)carbonate. Calcium carbonate is used to make soil more alkaline, but many houseplants actually prefer acidic soil. Sodium chloride is table salt, you definitely don't want that in your plants (see Soil salinity and salting the earth). --Dr Dima (talk) 00:11, 6 January 2011 (UTC)

You know, I don't think I've ever really thought about this before, but wouldn't it take kind of a lot of salt to make a large plot of land infertile? And salt used to be fairly expensive. The salting the earth article doesn't seem to provide any account of whether the method was actually effective, as opposed to symbolic. --Trovatore (talk) 06:06, 6 January 2011 (UTC)

I've long wondered if there was a chance that such stories didn't refer to NaCl but something else like copper sulfate that might have been available to the ancients from mining, or borax from desert evaporite deposits. But I've never seen the possibility mentioned let alone evaluated skeptically. Wnt (talk) 10:53, 6 January 2011 (UTC)

Salinity tolerance varies greatly among plants. For some orchids, a regular (not boiled-down) tap-water is often too salty. At the other extreme, there are quite a few plants that can tolerate ocean-water salinity level. Also, it matters a lot how you water the plants. If you remove the excess water from the saucer under the flowerpot every time, some of the salt is washed out. If, on the other hand, you let the plant "drink" all of its water every time, and never empty the saucer under the flowerpot, then the salt accumulates in the soil, and may kill the plant eventually. There are tables on the internet (e.g. here and here that quantify the salt tolerance of various plants. The tables use either units of concentration (ppm) or units of specific conductance (dS/m). A rule of thumb -- not exact! -- is 1 dS/m = 600 ppm. This roughly equals 0.6 gram of table salt per one liter water. In other words, if a quarter-gallon flowerpot has 6 grams of salt in it, you will have soil salinity of about 10 dS/m, which would kill some plants and stunt the growth of most others. --Dr Dima (talk) 21:01, 6 January 2011 (UTC)

January 6

Dragonfruit question

What are those things that look like artichoke leaves on the outside of the fruit of a dragonfruit, or pitaya? Wiwaxia (talk) 00:06, 6 January 2011 (UTC)

Bracts. Vespine (talk) 00:54, 6 January 2011 (UTC)

Oscar (fish) question

I've had a single Oscar for about 2 months and now I've just added 2 more. When I approach the tank, all 3 now come right to the top, and when I drop the food in, they all but attack the pellets, etc. But the single Oscar didn't do that when he was alone -- is this how they usually act when in groups? DRosenbach 04:20, 6 January 2011 (UTC)

I know really know, but I can only assume that they are running to the food to make sure to get it before it's all eaten. With just one there is no urgency. I assume that in the wild there usually isn't a concentrated source of food, and they just each search on their own for what they can find. (Again, this is just conjecture on my part.) It does remind me of something I read a while ago where someone was trying to breed an animal (some type of deer or gazelle) with no success - the male showed no interest in any of the females. Then one day males from other pens broke loose and the all ended up together - the competition from the other males stirred all of them, and all the females ended up pregnant. (The original author was rather more dramatic in how he described it, it's too bad I don't remember where it's from.) It seems that competition is not just for capitalism. Ariel. (talk) 06:32, 6 January 2011 (UTC)

Absolutely. The impulse towards competition can be absent when potential competitors are absent. 71.198.176.22 (talk) 14:07, 7 January 2011 (UTC)

evolution propaganda

Does anyone know of any evolution propaganda in the same format as the creationist pamphlets that you get from Jehovah's witnesses et al? I'm thinking of making my own but wondering if someone has done it already, I haven't really been able to find anything my self. Searching for "evolution pamphlet" predominantly gives results for the creationist ones. Vespine (talk) 05:38, 6 January 2011 (UTC)

What would be the need for such propaganda? Evolution has the weight of evidence on its side, it doesn't really need loud, garishly colored pamplets with words in all caps announcing that EVOLUTION IS THE DEVIL'S HANDIWORK or something like that. Science is generally publicized via peer reviewed journals and the popular scientific press; something the creationists lack access to, being that what they do isn't really "science". Hence the garish, badly made pamphlets. --Jayron32 05:54, 6 January 2011 (UTC)

Anyways, giving out pamphlets would only further expose the fact that evolution is desperately looking for support and evidence. --T H F S W (T · C · E) 07:04, 6 January 2011 (UTC)

Evolution can not look for support and evidence, it does not have a mind. Scientists have found a lot of evidence for evolution. I think THFSW is correct in the fact that evolution could loose credibility in the public if pro evolution propaganda pamphlets are distributed widely.--Gr8xoz (talk) 10:10, 6 January 2011 (UTC)

I would find such mock-tracts amusing. WikiDao ☯ 10:28, 6 January 2011 (UTC)

Does something that can be observed and there is no doubt about need propaganda?Zzubnik (talk) 10:34, 6 January 2011 (UTC)

In the USA, "no doubt" is the minority view, presumably because more people read Chick Tracts than Nature. --Sean 14:28, 6 January 2011 (UTC)

While those who reject evolution may be stronger in their beliefs for example show it about even with about 20% not sure. Level of support for evolution#Support for evolution in medicine and industry mentions something from 2007 where 49% believe in evolution although only 14% of the total don't believe god had a part. (This may seem to be a minority but I presume there are some 'not sure' there in particular while the citation seems dead the title suggestions it's 45% who believe in creationism.)Nil Einne (talk) 16:19, 6 January 2011 (UTC)

Your first link says, "In the U.S., only 14 percent of adults thought that evolution was "definitely true,"...". "Definitely true" is not a bad synonym for "no doubt", and 14 percent is certainly a minority, so I stand by my statement. --Sean 16:47, 6 January 2011 (UTC)

Apologies, I missed the 'no doubt' part. However I still have strong doubts about your statement. It seems unlikely the reason for the entirety of the 86% of the population who don't have 'no doubts' read or have had much influence from Chick tracts. Perhaps the 45% or whatever who believe in creationism at most. It's also questionable if reading Nature is needed. For starters, understanding journal articles can be difficult for those without much experience in the field. Also the evidence for overwhelming evidence for evolution has existed for so long it's well covered in far more accessible publications and in fact what is in Nature nowadays is often going to be limited and written without any consideration of the possibility of dispute of evolution. Nil Einne (talk) 21:57, 6 January 2011 (UTC)

There's also the question of where exactly 'no doubt' isn't in a minority. Not the UK for example . The survey referred in the earlier link appears to be from the supplementary material it appears in 2002-2003 only Denmark of the 10 countries surveyed had a majority with 'no doubt'. (United States), Poland, Netherlands, Italy, Spain, (Britain), Austria, Germany, France, had a minority having 'no doubt'. In fact France the highest after Denmark didn't even have 40%. So while it may be true the US lags behind most of the developed world in acceptance of evolution and from the ref, also differ in a number of ways, having only a minority with 'no doubt' isn't one aspect that differentiates them. BTW if you look at the main article, it has more countries but without the 'definitely true' part, interesting France is the 4th highest in this list of acceptance, and the UK is 6. Denmark is 2. Of course that doesn't mean at most 3 of the surveyed countries would have no doubt, it's 2-3 years in the future so attitudes would have changed and the different positions of countries tells us not surprisingly that potentially there's greater acceptance in some countries among the population even if fewer who think it's 'definitely true'. Nil Einne (talk) 22:07, 6 January 2011 (UTC)

You could always set up a new religion like L Ron Hubbard did. How about 'The Church of the Evolved Christ' where we have to evolve to get better, give Christ a blue skin too - that looks good. With a few million followers donating a tithe you could easily get them to produce pamphlets just like the creationists' ones and distribute them all around the world translated into a hundred and fifty different languages. How else would you distribute such pamphlets? How else would you get people to do anything with them except put them with the other paper for recycling? Dmcq (talk) 13:50, 6 January 2011 (UTC)

It could be fun to just change the words on Chick Tracts, like this one where Chick demonstrates to his own satisfaction that Jesus -- not gluons -- mediates the strong interaction. --Sean 14:28, 6 January 2011 (UTC)

I'm not sure how possible it is to mock something which is so inherently risible already. (It's not just physics, Chick even fails theology. Here he claims that Jesus's blood was not human blood, which is not exactly mainstream Christian thinking.) Marnanel (talk) 15:54, 6 January 2011 (UTC)

You make it sound like Chick Tracks are the supreme authority for anyone who doesn't believe evolution. The're not. --T H F S W (T · C · E) 17:17, 6 January 2011 (UTC)

Well, that first tract (the one with the irritable douchebag teacher and the tranquil babyfaced student) is a pretty good showcase of most arguments used against evolution. Ok, the gluon thing isn't exactly omnipresent, but open up any anti-evolution site and you'll find things like the ridiculous "six stages of evolution", the "carbon dating is inaccurate" silliness or the endless masturbation over the Piltdown man. TomorrowTime (talk) 18:47, 6 January 2011 (UTC)

Not terribly sure how you got that out of my words, or Sean's. I am sure even such people can see the foolishness of Chick tracts. Marnanel (talk) 18:32, 6 January 2011 (UTC)

I think you're looking to use your creativity to compose a novel joke, and that's not something that a science refdesk can really help you with much. You already have evolutionary theory - what you need is a mock religion to make it funny. Existing groups like the Church of the Subgenius might give you some ideas.

There is not actually any need for a conflict between religious creationism, which occurs in the dimension of time in which God authors and edits the universe, and scientific evolution, which occurs in the dimension of time in the universe as created. Just because the Foundation Trilogy covers many centuries doesn't mean that Asimov took that long to write it, or wrote it all in the order you read it. Wnt (talk) 18:44, 6 January 2011 (UTC)

I'm not trying to compose a joke. The fact that most of North America thinks people magically changed from lower animals is funny enough to me. --T H F S W (T · C · E) 19:10, 6 January 2011 (UTC)

As opposed to being magically created from dust (or ribs)? AndrewWTaylor (talk) 20:59, 6 January 2011 (UTC)

That happened due to an external influence. Different animals changing into one another is supposed to happen by itself. Would you say its weird for the keys on my keyboard to type out this message? No, because there's someone doing it. --T H F S W (T · C · E) 21:09, 6 January 2011 (UTC)

For THFSW: Introduction to evolution. You look markedly un- or mis-informed if you think the modern synthesis of evolution is "desperately looking for support and evidence" or that "people magically changed from lower animals". We have good articles on the subject; read them. — Scientizzle 22:02, 6 January 2011 (UTC)

...and keep reading. Unlike creationism, which is based on one unchanging, not allowed to be questioned, source, evolution is based on an ever growing body of knowledge being observed and interpreted by open minded scientists happy to change their minds when new evidence appears. HiLo48 (talk) 23:28, 6 January 2011 (UTC)

OP here, I was about to write, STICK TO THE QUESTION! I'm not starting a debate.. but i had to run and i thought it might be a little presumptuous, i was obviously wrong! lol.. I don't care if you think such propaganda is needed, i'm asking if it is around. I have some people close to me which have been given the creationist propaganda and it is making an impression on them. I understand "the weight of scientific evidence" is behind evolution, but there are obviously a lot of people not so scientifically literate who find a concise "to the point" pamphlet more convincing then "the weight of scientific knowledge". Thanks.Vespine (talk) 00:51, 7 January 2011 (UTC)

For the record, I agree with you that 1. the off-topic responses here have really gotten out of hand (which is entirely the answerers fault in my opinion), and 2. there's a lot of good reason to believe that good would be served if the basic arguments in favor of evolution could be condensed down into something that a "man off the street" could read, understand, and be convinced by.

There's plenty of evidence that the Chick tracts have been compelling; heck, even when I read some of them, I think, "gosh, this guy is a clever manipulator of emotions, even if he is a nut." Throwing scientific papers at laymen (even intelligent ones) doesn't do anything; appealing to scientific authority only gets you so far; and dismissing the "lay" opinion as unchangeable or, worse, irrelevant is dangerous and wrong as well. As for having examples of said good "propaganda" (which is really an unfortunate word to use because of its negative connotations), the National Center for Science Education produces a good number of pamphlets and short books that are aimed for this purpose. I'm not sure they have them posted online, and when I saw them (in the late 1990s, in their Oakland location), a lot of them were moldy golden oldies of an earlier time (arguing against Henry M. Morris and other, uh, transitionary fossils). But I'm betting if you wrote them or sent them an e-mail they'd send you some samples; they're a pretty generous bunch and I seem to recall the pamphlets being free anyway. --Mr.98 (talk) 02:38, 7 January 2011 (UTC)

Try "An Introduction to Evolution" from UC Berkeley's "Understanding Evolution" project. There are printable links on each page. I'm pretty sure it's as close as you're going to get to a religious tract about evolution, without the appeals to emotion, authority, or circularity. 71.198.176.22 (talk) 13:04, 7 January 2011 (UTC)

Or here! http://www.scientificamerican.com/article.cfm?id=evolution-the-story-of-life-on-earth 71.198.176.22 (talk) 14:29, 10 January 2011 (UTC)

Rotating momentum exchange tethers in LEO, drag and space debris

Does there exist a altitude range in low earth orbit were a rotating tether (Tether_propulsion#Bolo) for launch assist cold be placed?

I am thinking of a tether with the tip 50 km from the centre of mass and a tip speed of about 2 km/s relative to the centre of mass and an allowed load of at least 80 kN (1000 kg). It should be used by gaining orbital momentum by moving incoming objects from a high orbit to a lower unstable orbit and then give that orbital momentum to payloads launched by suborbital launch vehicles. The tether need of curse to be constructed with multiple strands for redundancy like the Hoytether. This would be part of a larger transportation system.

It must be operated at an altitude below most of the space debris in order to get a useful expected survival time. At the same time it will have high surface area and need to operate at an altitude where the atmosphere are thin enough to not generate a prohibitive high drag. Does such a altitude exist?

Would (micro) collisions with the tether generate a significant amount of new space debris? --Gr8xoz (talk) 11:07, 6 January 2011 (UTC)

I don't think we should assume that a tether needs to passively accept collisions with debris or other micrometeorites, given sufficiently effective sensors. To take a simple example, suppose that a tether has two cables separated by a few meters. If a piece of debris heads for one of the two cables, it temporarily relaxes its hold (perhaps at the expense of tightening in several other segments upward and downward). As a result, the loosened cable can be pulled out of the way toward that which is still taut, and the space debris flies through the hole. True, this requires a 2x redundancy factor, but only temporarily, and in case of catastrophic failure of the taut cable the lax one may still be able to hold the elevator while a repair module is dispatched to the site. And in practice I suspect that there would be quite a few more cables than just two, lowering the required strength-to-weight ratio needed for redundancy in all cases. Wnt (talk) 18:35, 6 January 2011 (UTC)

The ability to avoid collisions is very useful but I think there exist a gap between the debris that reasonable can be detected and the size of debris that can cut the tether. on page 180 or according to the pdf-reader 187 estimates that debris as small as 0.2 mm can cut a 1 mm strand. I think it is hard to detect so small debris if it is approaching at 15 km/s (page 164 or 171) --Gr8xoz (talk) 20:22, 6 January 2011 (UTC)

How do you plan to detect debris or micrometeoroids on the order of millimeters in dimension moving thousands of meters per second, especially far enough in advance to calculate the probability of impact and take action to move the tether? The tether WILL be hit with MMOD. I doubt that these small pieces would pose a new debris risk, though damage would accumulate over time and threaten the tether. A large, undetected object would also threaten the tether. So for any space elevator, this is a real problem with no easy solution. anonymous6494 19:56, 6 January 2011 (UTC)

To me, it seems absolutely unbelievable that people can track a satellite in Earth orbit, or even smaller bits of lost materials. Getting down to 0.2 mm is not that many orders of magnitude of difference. Also, pieces that are isolated specks and cut only a single cable should not really be so dangerous, because there should be periodic cross-struts between several cables, and repair modules that fix one broken cable while the others hold the structure together. After all, there will be spontaneous ruptures in the cables due to defects in manufacturing or deployment or during use, and the system will have to be ready for those. Wnt (talk) 06:32, 8 January 2011 (UTC)

"periodic cross-struts between several cables" is very important in order to get a useful expected survival time. I think that in order to not add to much weight this cross linking will need 100 m or so to spread the load evenly between the strands when a strand is cut. The problem is that the cross linking can not be allowed to pull the strands to close together since that would reduce the redundancy. I think repair modules requires a much more advanced technology and would increase the cost, remember, they need to climb in a acceleration from 0 to 80 m/s^2 and have to be mobile over about 70 km tether. They requires a rather good power supply to climb at any reasonable speed. I think a tether could handle between 100 and 1000 cuts during its lifetime without repair. For a lifetime of 10 years that translates to about 0.02 to 0.2 cuts per km strand and year. An additional problem are that each cut could produce new derbies and accelerate the problem.

--Gr8xoz (talk) 12:42, 8 January 2011 (UTC)

In practice, the performance of tethers in orbit has been very poor. They have failed spectacularly in several high profile incidents, and orbital dynamicists are so frustrated with their inability to accurately and usefully predict their behavior that they have been avoiding the use of tethers for at least the past two or three decades in microgravity orbital and outer space applications in favor of rigid, propulsion, formation flight, and balloon-based solutions to the same problems. Many if not most of the orbital tether failures are still not well understood, except that people now realize that they depend chaotically on initial conditions far more than was originally thought. I am pessimistic about the long term outlook for tether-based orbital dynamics solutions which do not make use of substantial propulsion and tension systems to stabilize them. It's not clear that the bolo launch assist mechanism couldn't be effected by a set of rigid structures. 71.198.176.22 (talk) 16:00, 8 January 2011 (UTC)

It would be interesting to read more abut these problems, do you have any useful links? I have not found any information on failures due inability to predict the orbits. There have been some failures in electrodynamic tethers and some single strand tethers have been cut by debris/meteoroids. Some very low budget experiments has had problem with deployment and telemetry. None of the these problems seems unsolvable to me except maybe space debris.--Gr8xoz (talk) 23:54, 8 January 2011 (UTC)

• http://articles.latimes.com/1992-08-09/news/mn-6218_1_shuttle-lands
• http://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=1996-012B
• http://articles.sun-sentinel.com/1996-03-04/news/9603030189_1_tether-columbia-returns-space-shuttle-columbia
• http://www.youtube.com/watch?v=JuFBUS0kiSA lol
• http://www.vectorsite.net/tarokt_5.html#m2 says "most experiments were successful" and lists many of them. 71.198.176.22 (talk) 14:00, 9 January 2011 (UTC)

Cause of vibration of a string

Project of “ ANKITIUM ” , The Unit Of Life :---------- When we make an approach to the string, we assume the mass, charge and energy as the fundamental properties of a particle. In this way of approach all of our thinking ends up to the Big Bang. We could not be able to know that how does it occurs or what was the situation before it occurs. But if we change our approach by considering the cause of producing mass, charge in an electron (or proton) from a string vibration, we might be able to find out the reason lying behind the Big Bang or the situation before the Big Bang.

Every mass contains some atoms. An atom contains a nucleus and some electrons. Nucleus contains protons and neutrons. Protons are positively charged, neutrons are neutral and electrons are negatively charged (It is our convention to assume that the charge in protons is positive and the charge in electron is negative.).

As all we know that vibration is the only way to transfer energy (such as thermal energy, sound energy etc.) from one place to another, we can conclude all of the energies can be created from vibration. As vibration takes place in different mode, different kind of energy can be produced at different mode of vibration.

Now, consider one electron. The electron is negatively charged. But from where does the charge come from or rather I would say where does it produce from? We can assume an electron as a negatively charged spherical cloud (as per electron’s wave nature). The radius of the spherical cloud is equal to the radius of an electron when it is considered as a particle. The spherical cloud implies the area of the electric field, produced due to the negative charge, in which it acts. In between this spherical cloud, there exists a vibrating string according to the String Theory proposed by Sir Stephen Hawking. The vibration is at one direction (say in anti-clockwise direction). This vibration produces some amount of energy. A part of which converts into a mass which is equal to the mass of an electron, obeying the famous equation E=mc2, of Sir Albert Einstein. Another part of this energy gets converted into some amount of charge, equal to the charge of an electron. This amount of charge produces a spherical shaped electric field which is called an electron in particle theory and electron cloud in wave theory, owing to the dual nature of the electron. Now, from where does the vibration of the string produce? In account to solve this problem, we can assume a string consists of many infinitesimally small units which are continuously getting compressed and elongated in success. These units can be called as the unit of life or rather I could name it after my girl friend, “Ankitium” (“Ankitia” in plural). But why does an Ankitium get compressed and elongated in success?

As we all know that the photons (unit of energy) are absorbed in multiple integrals of a quantum, energy of which is equal to ‘hv’ (h= Plank’s constant and v= frequency of the incident light). Our universe consists of different types of rays with different frequencies. Let, the different rays in this universe are of frequencies v1, v2, v3, v4....... and so on. Let us assume that v1=v. Hence, from Plank’s theory E=hv=hv1. An Ankitium absorbs the amount of energy in multiple integrals of ‘E’ or v1. When an Ankitium absorbs energy from the rays having frequencies which are of multiple integral of v1, the total energy of an Ankitium increases and the Ankitium reaches to a higher energy state. As a result, the Ankitium tries to elongate and a tensile force is built up. But all the frequencies must not be a multiple integral of v1. So, energy will not be absorbed by the Ankitium when the frequency of the incident photon are not of a multiple integral of v1. As a result, then the energy state of the Ankitium gets lowered and it comes across with a compressive force. Thus an Ankitium gets elongated and compressed in success. In case of protons, the vibration of the string must be at opposite direction that of in an electron. As a result, an amount of positive charge is produced. In the neutrons, the vibration must take place in such a way that it only produces an amount of energy which totally converts into a mass equal to the mass of the neutron. As a result, no kind of charge is produced in neutrons.- 61.11.120.66 (talk) 11:23, 6 January 2011 (UTC)

Is there a question in there? I didn't see it. SpinningSpark 11:42, 6 January 2011 (UTC)

I think the questions are 1) Where does an electron get it's charge from, and 2) Where does a string get it's energy from Zzubnik (talk) 11:56, 6 January 2011 (UTC)

I can't answer the questions because not even Stephen Hawking knows the answers. The charge of the proton is known to come from the arrangement of quarks, but that only moves the question one stage back and doesn't explain the charge of leptons. I don't think the "ankitium" will ever be discovered because strings are not believed to consist of matter, or to be in any way "divisible" (or even "real"), they are just mathematical constructs. The vibration modes of the strings are the mass, energy and charge. Alternative theories are M-theory and loop quantum gravity. Dbfirs 12:43, 6 January 2011 (UTC)

I agree, Dbfirs. This is somewhat like asking for a grand unification theory, or the answer to the question of life, the universe, and everything. Although, the answer to that last one is known to be 42. — Preceding unsigned comment added by Zzubnik (talk • contribs) 18:38, 6 January 2011 (UTC)

I asked a similar question just last month: Misplaced Pages:Reference desk/Archives/Science/2010 December 24#Why do superstrings "vibrate"? -- œ 19:13, 6 January 2011 (UTC)

What's the single best case for evolution?

The conversation about evolution above makes me think that we should pick out a single best case for evolution, a situation so well studied with so many different techniques that it provides a more than compelling argument. Of course, no evidence from the natural sciences can disprove that the world could have been affected by supernatural means, but the point to prove is that if someone made the world, it was deliberately made to look like it has a single consistent history going back millions of years which includes evolutionary change.

The case I want involves:

• Two points on opposite sides of the Atlantic Ocean, in places which visibly look like the continents once fit together there.
• The currently measured rate at which these two points are drifting apart closely matches the established breakup of Pangaea.
• Magnetic field reversals in the crust have been observed close to the line separating these two points, confirming a large number of reversals which match the time frame (though this is a weak argument, as a skeptic will argue the presumed reversal rate is only inferred from the data)
• A land species has been found fossilized near each of the two points.
• The radioactive dating of these fossils matches one another and the time at which Pangaea was breaking up.
• According to radioactive dating, fossils of this land species are found only during a narrow interval of time. However, transitional fossils closely link it to later species which continued to thrive on either side of the ocean, which are different on either side of the ocean. There should be as little confusion about this ancestry as possible.
• DNA analysis of modern living descendants of this species from either side of the ocean reveals differences between them. Modern phylogenetic analysis concludes that they diverged at about the period of time shown by the fossils, assuming mutation rates that are typical judging by those observed today.

I know that there are many situations where a few of these points are met. But I'd like to see an argument with sledgehammer strokes in which we show that geology, paleontology, radioactive dating, and conventional and molecular taxonomy all come together and show the same time frame over and over. That way the skeptic has to try to prove that most if not all of these disciplines are simultaneously wrong or conspiring to conceal the truth, an argument which becomes exponentially harder with each type of data that needs to be ignored. I know that finding such a case is very difficult, even for the expert - I'm just curious if people have in the course of disputations on the subject managed to hit across a good case that is suitably convenient and well-studied. Wnt (talk) 20:00, 6 January 2011 (UTC)

Peppered moth evolution is a common example, perhaps not as spectacular as you hoped for but it did take place in the blink of an eye rather than aeons. 92.24.188.182 (talk) 20:27, 6 January 2011 (UTC)

(ec): How about this paper on E. coli long-term evolution experiment? --Dr Dima (talk) 20:29, 6 January 2011 (UTC)

Guys! Neither of those examples have anything to do with the above post other than the heading. Did you read the post? Please don't bother posting an answer if you haven't read the question! --Mr.98 (talk) 20:56, 6 January 2011 (UTC)

The OP lists so many criteria that its unlikely that anything can fulfill all of them. So in the abscence of that, other examples of evolution were given. 92.24.188.63 (talk) 00:22, 7 January 2011 (UTC)

No, I did read the question. The OP asks for "single best case for evolution", and both my reply and that of 188.182 give examples of some of the best cases for the evolution. I simply do not think that "combining many different techniques that it provides a more than compelling argument" is a good educational strategy in this case. The reason is, whatever scientific evidence of evolutionary history -- no matter how compelling -- you present to a person who thinks the world was created as-is 5800 years ago, fossils and all, it will not alleviate that person's doubts. But if you show this person a colony of bacteria that has actually evolved to metabolize citrate literally in front of researchers' eyes, you may actually have a compelling argument that evolution does happen. --Dr Dima (talk) 21:27, 6 January 2011 (UTC)

The question qualifies very heavily what it means by the "single best case", and your answer ignored that completely. That's what I meant by it appearing not to have read the question. --Mr.98 (talk) 21:29, 6 January 2011 (UTC)

Regardless of the example, this attempt will fail miserably. People who do not want to believe in evolution will not believe in evolution. Another way to put it is: You cannot reason a person out of a belief that they formed without reason. No matter what you attempt to prove, the response is simply, "God made it look like that" - the religious equivalent of "a wizard did it." -- kainaw™ 20:31, 6 January 2011 (UTC)

Your arguments seem more in favor of Plate Tectonics Theory than the Theory of Evolution. As for the strongest support for evolution, I'd have to go with dinosaur bones. There are many skeletons of nearly intact dinosaurs, which are completely inconsistent with the Biblical record. The number and variety of those skeletons shows that there were many eras of dinosaurs. So, which day of Biblical creation were these created ? It just doesn't fit. And, unlike radiocarbon dating, the Big Bang Theory, etc., it really doesn't require any great scientific understanding to look at a T-Rex skeleton and see that it is very different than anything in human experience (or Biblical accounts). StuRat (talk) 21:10, 6 January 2011 (UTC)

Creationists have long made their peace with dinosaurs. (They would have been created on the same day as the other animals, incidentally.) See e.g. this particular discussion. What the OP is asking for is something that is totally scientifically air-tight, not something that appeals to the common man. --Mr.98 (talk) 21:29, 6 January 2011 (UTC)

But that doesn't explain why the Bible didn't mention them (how about a full inventory, just like the "begets" ?). Also, are they supposed to have all died on that same day, too ? If so, why ? And are we taking the Bible literally, so that they only existed for 24 hours ? StuRat (talk) 22:42, 6 January 2011 (UTC)

It doesn't mention a lot of animals, either, and in fact, as the page points out, big, dinosaur-like creatures (and dragons) are mentioned far more than a lot of other common world critters. It's not meant to be an atlas of all animals. I'm not a Creationist at all, but purposefully misreading the Bible (like the idea that they existed for 24 hours, which nobody contends) just sets up a rather foolish straw man, which is convincing to none. If you want to be truly convincing, you argue against the best oppositional case, and show why it is wrong. Not the worst. --Mr.98 (talk) 00:35, 7 January 2011 (UTC)

OK, then, just what is the strongest Biblical case ? The other one I've heard is that dinos were around until The Flood and didn't make it onto The Ark. That seems even more absurd though, if they were supposedly running around with people, as in The Flintstones. Is there also an idea that they were around with Adam and Eve, but died out soon after ? StuRat (talk) 04:09, 7 January 2011 (UTC)

It's creationism that's based on a single, unchanging, unquestioned source. Evolution, like all science, is based on an ever accumulating set of knowledge, combined with an ever questioning community of scientists. The knowledge is massive. Heck, Darwin's voyage in the Beagle took five years! Those who want to believe in creationism are missing most of that knowledge, or choose to ignore it. They oppose letting children have the former and will continue to ignore. HiLo48 (talk) 21:24, 6 January 2011 (UTC)

As the form of the question makes clear, the dispute about evolution is really a surrogate for a dispute about a far more important question, the age of the Earth (and the Universe). The two contending hypotheses for the age of the Earth are (1) about 4.5 billion years (modern science); (2) about 6000 years (biblical literalism). As an argument in favor of the scientific age, the one given above is pretty strong, although not necessarily the strongest possible. It is basically impossible to support an age of 6000 years without assuming that the visible universe is at most 6000 light years in size, which pretty much trashes modern physics. Looie496 (talk) 21:26, 6 January 2011 (UTC)

There is a fundemental flaw in the question itself, in that it assumes that theories like evolution are built on isolated pieces of evidence, and that some of those pieces of evidence are better than others. This isn't how science works. The theory of evolution is a working theory, and has been for the better part of a century. No one works at building evidence for it, they just use it as background understanding for their research, and the research works. In a sense, all of biology and its subdisciplines has evolution as one of its cornerstones, and insofar as every experiment in biology and subdisciplines works, that's the evidence. All of life is itself the evidence for evolution. The flaw in the question asked in the title of this thread is why the creationist/intelligent design crowd always ends up fighting the wrong battle. There is a belief that evolution (and indeed science) works only if every single piece of evidence that exists is correctly interpreted, and completely true. If you can find one error, or find one single thing that does not yet have adequate explanation, then the entire system is completely and utterly wrong. This sort of reasoning showed up in the defendant's testimony at Kitzmiller v. Dover Area School District, the most important trial case since the Scopes trial in this area, and forms a major part of what is known as the Wedge strategy known as Irreducible complexity. The idea being that certain key elements of living systems, as yet unexplained by science (classic examples are the eye and the flagellum) can be used as the point of the "wedge" to drive into evolution, and prove it wrong. The OP's question presumes the same sort of misguided reasoning, that there are "best examples" and "wrong examples" and that we merely need to put forth the "best examples" to prove evolution or the "wrong examples" to disprove it. --Jayron32 21:33, 6 January 2011 (UTC)

Furthermore, all observational evidence is moot, because it is fundamentally impossible to verify the existence of "reality." This isn't new; Allegory of the Cave predates Christian thought; and the philosophical concept has been re-hashed out by every major school of thought, from rationalism to post-modernism. If somebody doesn't want to accept observational evidence as proof of reality, it doesn't matter how solid your observational evidence is. At best, we can prove that "I perceive something." The next step, "I assume that my perceptions represent a real, natural, material world" is completely unfounded. Religious belief attacks scientific thought at this level by presuming that a supernatural reality exists beyond anything which we can perceive. So, purple unicorns, space teapots, and all that. Nimur (talk) 21:45, 6 January 2011 (UTC)

(Pedant) I think you mean pink unicorns and purple oysters . CS Miller (talk) 00:19, 7 January 2011 (UTC)

Burn the heretic! --Stephan Schulz (talk) 09:52, 8 January 2011 (UTC)

The case for evolution is the same as the case for any other well established scientific theory: It is a simple explanation for our observations. There is no other explanation that even comes close. --Tango (talk) 00:10, 7 January 2011 (UTC)

The best argument I can find against young-Earth creationism is varves. Unlike dating based on radioactive decay, varves provide a very direct, very simple to understand measure of the geological passage of time, even to people with a very weak understanding of any branch of science. And the six million varve depth of the Green River Formation shows that the Earth is at least six million years old, which although that's only a small fraction of the total age of the Earth, is still vastly older than is thought by anyone who measures the time since creation in the thousands of years. However, I still had no luck convincing some Jehovah's Witnesses I talked to that the Earth is at least millions of years old. They didn't have any explanation for the six-million varve depth of the Green River Formation, but they really didn't care. Some people are just going to believe what feels good to believe, regardless of what the evidence says.

What I think is one of the best arguments for evolution are the Australian marsupials (Australidelphia). There are scads of different species of them, but there are biological similarities among them that aren't found elsewhere in the world. Why all those different species of biologically similar animals happen to only be found in Australia is easy to explain with evolution, but hard to explain if all of those different species independently made their way to Australia somehow from Noah's ark. But like with the varves, although the Jehovah's Witnesses I talked to had no explanation for the geographical isolation of the Australidelphia, that didn't actually affect their beliefs. They just didn't care. Red Act (talk) 01:47, 7 January 2011 (UTC)

All observational evidence, even varves, is counteracted by "God made it that way". It's a pointless arguement. Either people are prepared to accept that God created the world as it really exists, with evolution and the Big Bang, and all of it, or they believe that God created the world as they wish it to exist, on a Tuesday morning about 6000 years ago. If they believe the latter, the believe it without any need to look for evidence for how God really made the world. So any evidence you provide is pointless. --Jayron32 02:56, 7 January 2011 (UTC)

Your third sentence is a false dichotomy, in that it assumes that all possible belief possibilities include the belief in the existence of a God that created the world one way or another, which is not a valid assumption. Red Act (talk) 05:28, 7 January 2011 (UTC)

True, you could take God out of the picture and have the same arguement though; he's optional for the point of argueing the validity of evolution in this case as an aside, I do not find God personally optional; as an evangelical Christian myself, I find God pretty mandatory to any of my own belief systems. I also recognize, however, that it isn't necessary for this particular arguement, and so I won't belabor the issue. However, if your point is to help those who believe in God also accept the validity of evolution, its probably more helpful to show how evolution is not fundementally contradictory of anyone's religious belief. If you imply that God and evolution cannot coexist in the same belief system; then you fall into the same exact faulty thought processes that make it so that the strongly religious refuse to accept evolution. Argue the important point; which is the reality of evolution, not the unimportant point, which is the existance of God. unimportant, I might add, to the validity of the case for evolution, not in general. See my aside above. --Jayron32 06:21, 7 January 2011 (UTC)

If God's so smart, why does He simply not tell us what we should believe about evolution? Why leave us guessing? He dosnt reply to prayers etc, has no address, no telephone number, no webpage, no nothing. Do you think He has passed on? On the other hand, when I pray to Santa Claus at the right time of year, He (Santa I mean) brings me presents. Next time I see Santa, I will ask him what the trutrh regarding evolution is. 92.24.183.6 (talk) 16:58, 7 January 2011 (UTC)

Well, he doesn't reply to YOUR prayers. Or maybe he does, and sometimes his reply is "No". --Jayron32 20:06, 7 January 2011 (UTC)

Is the pronoun "He" for Santa and "he" for God ? Cuddlyable3 (talk) 01:56, 8 January 2011 (UTC)

For the OP, a good start would probably be a book like The Greatest Show on Earth: The Evidence for Evolution by Richard Dawkins. If anyone is going to summarize the best arguments in support of evolution it is Dawkins. You might also want to look at our article on biogeography which briefly discusses some evidence based on paleogeography, plate tectonics, and molecular analysis of fossils. --- Medical geneticist (talk) 03:08, 7 January 2011 (UTC)

I had a feeling it would end up in Dawkins... I'll have to actually read him the next time I happen across a copy. I should clarify though that I understand that such a perfect example is not necessary to justify the idea scientifically, and it is also not sufficient to disprove the religious idea of creation. The point is to justify to creationists the idea that the universe is truly a four-dimensional work of art - a story for which a very long past has been written. The creationist does himself an injustice when he fails to consider that if God wanted our planet to have a consistent, logical, richly detailed history stretching back hundreds of millions of years, it means that there is something to be learned from it. Wnt (talk) 10:13, 7 January 2011 (UTC)

You won't find such an arguement in Dawkins. His stance on Evolution is a pretty good read, however he's rather intolerant towards any religious worldview. His writing on religious issues is quite bitter and angry, and not at all "rational" if you ask me. The God Delusion, for me at least, comes of as no less dogmatic than any religious apologetic text. --Jayron32 14:09, 7 January 2011 (UTC)

As an aside, if you want to read someone who DOES do a good job of balancing the religious worldview with the scientific one, might I recommend Stephen Jay Gould, especially Rocks of Ages. --Jayron32 14:14, 7 January 2011 (UTC)

The Speciation article has some concrete examples of natural and artificial speciation which make the case pretty well. 71.198.176.22 (talk) 13:12, 7 January 2011 (UTC)

Wnt - that's a significant comment about time being a critical factor. Evolution has created the complexity we now see through having 3 billion years in which to do it. And there's one of the big stumbling blocks. A creationist argument is that evolution couldn't have created what we now see in the pathetic 6,000 years which they think their god tells them it's had. And they're right. It couldn't have happened in 6,000 years. Dunno what "single best case" we could use to get over that hurdle. HiLo48 (talk) 04:01, 8 January 2011 (UTC)

Even a much less than omnipotent god could get past the physics difficulties if it were required - you could say, he just blew on the continents early on to separate them much more quickly than in the current day. But the difference is that such a minor deity would leave no field reversals in the part of the ocean that was separated in some rapid semi-cataclysmic fashion. Now a suitably powerful deity can get all the tricky little details right, but doing that displays a deliberate intent to make the result match what would occur from the physical processes observed by natural scientists. The point is not to show that the natural science model is absolutely true, notwithstanding supernatural intervention. It is to show that it is meaningful - that even God thought it was important to keep the theory consistent! I should point out that even a run-of-the-mill atheist can read Hitchhiker's Guide to the Galaxy and at least suspend disbelief on a model in which an alien species perfectly recreates the Earth after it has been destroyed - for people on such an Earth a nonreligious creationism is actually the truth, and yet one supposes that it is still useful for them to study evolution. Of course, with anything less than an omnipotent, omniscient deity, the errors will eventually show. Actually, it has sometimes been my speculation that this really isn't the original Earth, but a historical recreation of the first period of history that was recorded well enough to make a decently accurate simulation, and occasionally I am prone to wonder whether certain details are errors in it. (For example, I've wondered whether a primate species capable of such amazing feats of acrobatics truly could not manage to put one of a few keys into a lock without fumbling around for half a minute; perhaps the original humans did this only as a matter of politeness? But I digress!) Wnt (talk) 04:57, 8 January 2011 (UTC)

I am prepared to believe in a God that has created the world, by Intentional Design, so that it very cleverly in all its details is entirely consistent with modern Evolutionary biology (and Evolutionary psychology, too, and so on).

But the overwhelming weight of all the available evidence, and the learned consideration of it, supports -- is consistent with -- the possibility that it has all occurred the way it has over the course of aeons without any need for any "Divine Guidance" of it according to some divinely "Intelligent Design" of it.

But, still, God, for reasons of God's own, could have made it just look that way – exactly as if there is no need for a God even though there really is a God! Right? But... what difference would the existence of such a God make? And why would God want to do that? If it is the God of the JudeoChristian bible that you believe to be behind such diabolical trickery, could it be because that God is a very "jealous" God, and just wants to test to see if we will still "believe" even though there is absolutely no good reason to do so on the basis of the evidence that God has seen fit to make available to us...? Do you think a God capable of "creating" this whole world in all its unimaginable vastness and complexity would really be inclined to such childish games?

I am prepared to believe in any God in Whom there is any good reason or cause or use to believe in. That God is welcome to make Its existence known to me at any time. If you have some reason to believe in the God you believe in -- well, God bless you and more power to you. But don't assume that reason or that God must necessarily exist for anyone else - and I recommend just leaving it at that, especially here at the Science desk. WikiDao ☯ 05:26, 8 January 2011 (UTC)

The "no need for God" part is tricky. Very tricky. The universe could have operated "spontaneously" with a set of physical laws that didn't allow for life. The strong anthropic principle suggests that we just happen to see the universe which allows us to exist. But what does it mean for us to exist? To perceive things? Why doesn't a fire, say, count as having a perspective that it devours fuel and responds? Why aren't its ever-changing currents as capable of feeling and experiencing as our brains' electric currents? (Then again, I suppose I don't know for sure that they're not...) The point is, this idea that things can be experienced comes from somewhere. The ideas that there's such a thing as space, such a thing as time, such a thing as perception, such a thing as thought, where do these come from? The materialistic idea that matter just exists and knows what to do by some laws of physics, all without any designing intellect ... it seems like a shell game. God has just been swept into tidy little corners, The Mind's I kind of stuff, where we find the philosophy so hard to think about that we ignore it. But it's not a meaningful settlement.

The simplest way to describe the difference between the purpose of religion and that of science is to picture the universe being intelligently designed in stages, like a draft that is gradually written and revised by an author. If you picture space as a movie, and take one "frame" of three-dimensional space frozen in time, then the relationship of that frame to the ones before and after it as defined by physical laws and perceived by mundane consciousness is one temporal dimension. God's involvement in that dimension is deliberately very small, and may not be distinguishable from the indeterminate laws of physics. But another dimension of time links a frame to a different frame in which a process of divine authorship and revision is going on, according to its own supernatural laws. Thus there is a linear succession of parallel universes in a fifth dimension, which is defined as "God's sense of time". This is particularly consistent with Christian theology in particular, which postulates that the universe was created on a succession of days (in God's time only, as there are no humans described to see the first few days) leading to a small, simple, easy universe, which is then replaced by a series of more complex universes, and where even the current universe is not the final form, but is to be replaced by a perfected version. Wnt (talk) 06:25, 8 January 2011 (UTC)

For most religions the thing you have to get across is that their religion does not require them to believe evolution is wrong. Some of their teachers think it which is a different thing altogether. They don't have to believe in a God who is scheming to test them with tricks like having layers and layers in the mountain dating back millions of years when it is only their teacher who believes in the six thousand years dateline. Do they really want a God that plays silly tricks? Dmcq (talk) 14:34, 8 January 2011 (UTC)

I agree, Dmcq: it is important not to try to just rip a person's religion away before they have a better sense of how they could get along just as well or better without their beliefs. Permit God, but explain the Science... and then let them come to question their notion of God on their own.

In your case, Wnt, I get the impression you've already got some Science and would like to keep your God, too. Fair enough. I suppose the main criticism I would have of your comments above would be the extent to which you are implicitly anthropomorphizing God. Perhaps this stems from that "created in the image of" business in the Bible, I don't know. But if you are going to believe in a God that thinks (which implies not just "knowing" some things at some times) like us and feels (including "jealousy") like us and acts (including "designing") like us – well, first of all, that's a really imperfect God! If you waive that apparent imperfection away as part of a mystery that is beyond us – well, what good is the concept of a mysteriously imperfect "perfect being"? It sounds more like just sloppy thinking to me.

Any Absolute Being should be beyond "personality" in any comprehensible sense. In fact, saying anything at all about such a Being artificially limits that Being into belonging to our own personal, cultural, etc. conceptual categories and linguistic usages. Which is why, presumably, Buddha, for one, refused to even say a word on the subject: you say a word, you get it wrong, and trying to say anything just causes endless confusion, so why bother? Similarly with Science: there is no need to understand how the universe works by appealing to some person-like Creator and Designer, and doing so just is not very useful, so why bother? There is no need; and eg. Evolution can be understood better without having to do so!

That still leaves room for various personal beliefs in God, in which, depending on the person, there may be some utility. But the Universe does not require it. It works just fine whether you believe in it or not. (And no God I would care to believe in would be so weak and emotionally clingy as to "need" me to believe in It!) WikiDao ☯ 18:10, 8 January 2011 (UTC)

Actually, you're wrong about the order of things. Twenty years ago or so, I was very close in thinking to Richard Dawkins, frequently denouncing religion as a virus and so on (when I began the word "meme" hadn't been invented yet). I was greatly appalled by the use of religion to promote injustice, arbitrary restrictions on behavior, and mindless cruelty. But a large number of things came to change my mind. One was the sterility of libertarianism - despite the goal of people to promote freedom in a general sense, the rhetoric sours into lunatics who want to copyright every word of every sentence and defend their right to "respond to violence" if someone infringes that. It is a philosophy that starts on the right track, but doesn't have any sense of direction, and hasn't led people anywhere. Meanwhile, one appreciates the tremendous strength of movements like the SCLC and Martin Luther King, Jr. which were not afraid to look for a broader spiritual basis. I should also mention Peter McWilliams' Ain't Nobody's Business If You Do, a surprisingly strong defense of libertarian Christianity, and a protester at an abortion clinic who withstood my tirade and convinced me of his inner sincerity, as well as a highly ill-considered foray into the genuinely paranormal. After some evaluation I concluded from the history that the belief in individualism, free speech, and liberty in general was derived in large measure from the message of universal and absolute love in Christianity, with some important additions from Laozi via Gandhi and Martin Luther King, Jr. Secular enlightenment, by itself, is like a vehicle that one can drive some distance - but the religious background ultimately provides the sense of purpose that is the fuel. I don't mean to say anything negative about atheists in this context, because as we've all seen, one can (all too easily) have a conception of God that has no inner reality, and likewise one can have a view of atheism that leaves room for a sense of deity under some other name.

Now as for the meaning of a personal God, this is a very sectarian issue - even many Christian groups did not consider the Old Testament as part of their doctrine prior to Constantine I, who began the persecution of heretics as once all Christians had been persecuted; it was part of an all too commonplace effort of a government to take a religion and use it for its own purposes. But to make an imprecise analogy, the Earth is vast, and yet personal - we go here and there, and touch the stones and the soil, and see many different facets of its beauty and also of its pain; and yet we shall return to it, our atoms commingled with all the others. Wnt (talk) 19:12, 9 January 2011 (UTC)

Well as Laplace said I have no need for that hypothesis. If other people want to believe that sort of thing it's fine by me. I do think it is a pity though for people with their finite span on earth to obscure their minds with weird stories. Dmcq (talk) 21:39, 9 January 2011 (UTC)

All very interesting, but yes I agree we are now not only way off-topic but way off-desk, too. ;) Regards, WikiDao ☯ 01:23, 10 January 2011 (UTC)

As a parting shot I should point out that the "finite span on earth" is itself a religious view: in modern materialism it is assumed that everything that happens to a person is perceived (even if it is forgotten in an alcohol blackout or subsequent Alzheimer, stroke, etc.; but that nothing that happens to another individual is sensed by a person. The "person" is defined as a physical brain, rather than as, say, a general process or algorithm, such as an Atman like universal force of consciousness. I would say thus that materialism also is a story that obscures the mind, because while the "person" or soul may be a piece of software that should be developed and made worthy of being preserved in a future release of the universe's operating system, they nonetheless all run on the same core processor. Wnt (talk) 15:47, 10 January 2011 (UTC)

Wnt, there are plenty of places for the publication of sophomoric musings and irrelevant memoir. This isn't one of them. Self-edit, please. 63.17.76.203 (talk) 03:21, 11 January 2011 (UTC)

Lost in taxonomy

A Pliosaur discovered in Stretham in 1952 and discussed briefly in that article is causing me some nomenclature concern. In his 1959 paper, Tarlo argues that "... the characters of the anterior cervical vertebrae show that the Stretham specimen belongs to the species P. macromerus Phillips ..." then goes on to suggest "... a new generic name necessary for P. macromerus. The name Stretosaurus gen. nov. is chosen as it seems fitting that the village of Stretham where this giant skeleton was discovered should be commemorated".

What does Tarlo mean? Is he suggesting Stretosaurus gen. nov. is a synonym for P. macromerus or even P.? Confirm P. is the genus and in this case is Pliosaurus. How should I refer to this extinct animal? Is it a Stretosaurus, a Stretosaurus gen. nov., a Pliosaur, a P. macromerus, a Pliosaurus, all of the above or a what?

yours sincerely, very confused --Senra (Talk) 21:19, 6 January 2011 (UTC)

You will find further reference to this question, which may or may not clarify, in the article Liopleurodon. 87.81.230.195 (talk) 15:52, 7 January 2011 (UTC)

Thank you 87.81,230,195. Just to be very clear here, I am refering to the specimen with the Sedgwick Museum catalogue number: J. 35990 a–z, aa–zz, A–Q. I have looked at Liopleurodon which seems to suggest

Stretosaurus macromerus Tarlo 1959 -->

Liopleurodon macromerus relegating Stretosaurus to a junior synonym of Liopleurodon Halstead 1989 -->

Pliosaurus macromerus Noè 2004

implying (to me) I should refer to this animal as a Pliosaur, P. macromerus? Am I correct? --Senra (Talk) 00:08, 8 January 2011 (UTC)

The Pliosaurus article mentions the species with no content on a dubious classification, so yes, I think you're right. Crimsonraptor | (Contact me) Dumpster dive if you must 00:21, 8 January 2011 (UTC)

Having now tried to read the minefield which is represented by the Misplaced Pages articles on Taxonomy, Alpha taxonomy, Biological classification, Author citation, Synonym and International Code of Zoological Nomenclature, I feel the need to modify this particular Pliosaur species references to P. macromerus Phillips, 1871 --Senra (Talk) 14:13, 9 January 2011 (UTC)

Followup on element symbols

In chemical symbols like
₆C
what is the purpose of the left-hand subscript (6 in this case)? Chemical symbol says it's the atomic number, but that's already known from the element name. Why the redundancy? --Sean 22:17, 6 January 2011 (UTC)

Chemical formula#Isotopes notes, "This is convenient when writing equations for nuclear reactions, in order to show the balance of charge more clearly." DMacks (talk) 22:30, 6 January 2011 (UTC)

(ec) Nobody needs that for Carbon, because "everybody" remembers the atomic numbers of the first twenty or thirty elements. But Yttrium and Ytterbium, now that's a whole other story! Heck if anyone can remember the atomic numbers of all hundred or so elements. Particularly in nuclear chemistry when we have a lot of nuclei on the paper, and a lot of changes and intermediate products, it's convenient, albeit redundant, to annotate the atomic number. Nimur (talk) 22:31, 6 January 2011 (UTC)

(ec, continuing my thoughts) In general, if the whole focus of some discussion is centered on the nuclear charge (for whatever reason), may as well just state it instead of having to look it up, and especially for cases where the atomic symbol is not universal (systematic vs eventually blessing by IUPAC, or international language differences). DMacks (talk) 22:37, 6 January 2011 (UTC)

As an addendum, nuclear physicists also draw the periodic table a little differently than regular chemists: Table of nuclides (complete); it visualizes the information differently and makes it easy to draw decays and reactions on the chart. Nimur (talk) 22:38, 6 January 2011 (UTC)

It's not strictly necessary, and you'll find lots of instances where it is dropped. But it's convenient. --Mr.98 (talk) 23:14, 6 January 2011 (UTC)

Why does a grape soda stain on a white paper towel look like a bird map?

A small paperback book I've had since I was a child has pictures of familiar American birds and shows a map of where they live. The summer range is pink, and the winter range is blue. Some birds can live in certain areas year-round, so the area where the ranges overlap is purple.

One would think a grape soda stain would be purple.Vchimpanzee · talk · contributions · 22:41, 6 January 2011 (UTC)

The pink/blue map overlay sounds characteristic of the Peterson Field Guides A Field Guide to the Birds; I have found those to be better than the official National Audubon Society bird guides. Do you have a question? Nimur (talk) 22:59, 6 January 2011 (UTC)

The question is hidden in the section title (annoying but common) and would appear to ask about the separation via paper chromatography of the various pigments in grape juice. -- 119.31.126.67 (talk) 00:33, 7 January 2011 (UTC)

It is really a shame that that article has no illustration in it. I seem to recall endlessly doing this experiment as a child, where you separate out black ink into its component colors. It's a very vivid illustration of a basic concept, and easy to do if you have the right materials (e.g. a bottle of blank ink). Anyone game? --Mr.98 (talk) 21:07, 7 January 2011 (UTC)

India ink ? Cuddlyable3 (talk) 01:51, 8 January 2011 (UTC)

No, as that's made of soot, it won't separate. Thin layer chromatography has a pic which shows it, but I've done it before with a circular filter paper + a black felt tip. SmartSE (talk) 14:53, 8 January 2011 (UTC)

ER

can anyone tell me the names of tv show's where they take you into the emergency room and show whats going on ? example

http://www.youtube.com/watch?v=j0p74MgfV-8 — Preceding unsigned comment added by Tommy35750 (talk • contribs) 22:54, 6 January 2011 (UTC)

Sorry to be blunt, but what has this got to do with science? You'd be better off asking the uploader of the video on youtube. SmartSE (talk) 23:11, 6 January 2011 (UTC)

Why the need to bite the questioner? The link to science seems pretty obvious: a desire to see examples of the science (admittedly sometimes considered an art) of emergency medicine in practice. Edison (talk) 00:41, 7 January 2011 (UTC)

We have many entries in Category:Medical television series. ER sounds a lot like what you describe? DMacks (talk) 00:24, 7 January 2011 (UTC)

I think the OP is looking for documentary material, not drama. SpinningSpark 01:23, 7 January 2011 (UTC)

I think it's Trauma: Life in the E.R. APL (talk) 00:45, 7 January 2011 (UTC)

The OP does not make it clear whether he wishes to know about actual medical emergency departments or fantasy fiction. Richard Avery (talk) 07:43, 7 January 2011 (UTC)

I don't think they are asking about this show, but any show that covers the subject. 72.2.54.34 (talk) 01:01, 8 January 2011 (UTC)

It is a fact that the OP chose not to post the question at the Entertainment desk. Cuddlyable3 (talk) 01:47, 8 January 2011 (UTC)

January 7

Yellow zinc passivated screws and chrome-6 carcinogen

I've bought some "yellow zinc passivated" woodwork screws, and after looking up on the internet what "passivated" means, I've found information like this page http://www.ewes.se/doc.asp?M=100000096&D=600000326&L=EN which says that some kinds of passivation use a "grade 1" carcinogen, described as chrome six, and are in the process of being banned by the EU.

The screws I've got look reddish with a little pale green rather that the "yellow" of the label. Have I bought the bad kind that are beginning to be banned? Thanks 92.24.188.63 (talk) 00:15, 7 January 2011 (UTC)

See zinc chromate. --98.221.179.18 (talk) 01:19, 7 January 2011 (UTC)

I understand that what is to be regulated are the exposure of industrial workers to the carcinogenous chemicals, and use of the plated surfaces in medical or food preparation applications. The woodwork screws may one day be marked Unsuitable for these but I doubt that sale of them will be banned.Cuddlyable3 (talk) 02:11, 7 January 2011 (UTC)

The answer appears to be "probably". Hexavalent chromium and passivation are relevant. 92.24.178.121 (talk) 11:11, 7 January 2011 (UTC)

I agree; avoid exposure to hexavalent chromium. If you're just using a handful of screws, wear gloves and/or wash your hands. If you're a carpenter, buy galvanized screws or screws passivated with a different oxide instead. 71.198.176.22 (talk) 14:00, 7 January 2011 (UTC)

It is better to get other types of screws like galvanized ones. --98.221.179.18 (talk) 21:48, 7 January 2011 (UTC)

The passivateisation (sp?) is applied on top of the zinc galvanisation, and is said to reduce the corrosion by several times beyond that of plain zinc galvanisation. There are various treatments that can be used to do the passivateisation, and I'm not clear which are believed to be harmless. Dipping the screws in paint might be an alternative to passivatisation, although I don't know by how much this would reduce corrosion. 92.15.24.121 (talk) 11:31, 8 January 2011 (UTC)

Of course it's a cost-benefit analysis with corroded screws on one hand and decreased lifespan and medical bills from cancer on the other. It just seems inconceivable to me that there isn't a nontoxic alternative of approximately equivalent cost and effectiveness in this case. 71.198.176.22 (talk) 16:39, 8 January 2011 (UTC)

New Jersey Department of Fish and Wildlife field guides

I would like to know if these are copyrighted. --98.221.179.18 (talk) 01:19, 7 January 2011 (UTC)

Probably. In the U.S., the only things which are safe to assume are in the public domain are those a) expressly released into the public domain by the rightful copyright holder b) published before 1923 or c) published before 1978 whose copyright was not registered or renewed properly before 1978. Anything created and published since 1978 is presumed to be under copyright to someone unless expressly released into the public domain. --Jayron32 02:45, 7 January 2011 (UTC)

Things created by an employ of the federal government, as part of their capacity as a federal government employee, are also considered non-copyrightable: Copyright status of work by the U.S. government. However, this does not apply to state governments or employs. The State of New Jersey specifically claims copyright to the NJDEP Division of Fish & Wildlife webpage (at the bottom), so I think it's likely that they'd claim copyright to the guides as well. I don't see a specific copyright claim on the guides, but as Jayron pointed out, there doesn't need to be a claim to copyright to be copyrighted. It also remains unclear whether the state of New Jersey holds the copyright to the work, or the authors ("Schwartz, V. & D. Golden", as attributed). I am not a lawyer, but in general, I believe it's only the owners of the copyrighted material that are allowed to sue (or issue Takedown notices)

Of course, depending on what you're using the material for, copyright may or may not matter. Something like Wikimedia Commons will only accept work that is truly under a free licence, but in many cases, if you're confident that the copyright holder won't sue, you can do whatever you like with the material, irrespective of the law. I'm not sure if the state of New Jersey (if they are indeed the copyright holders) is likely to sue anyone over some obscure field guide, even if they don't do find out. If you intend to use the material in any serious way, it would be a good idea to seek the advice of a lawyer. You could also send a polite e-mail to the New Jersey Department of Fish and Wildlife inquiring about the work. Even if they aren't willing to release the material under a free licence, they may be willing to grant you permission to use it in specific ways. Buddy431 (talk) 03:38, 7 January 2011 (UTC)

Edit: NJ Division of Fish and Wildlife Contact Info. Buddy431 (talk) 03:46, 7 January 2011 (UTC)

Edit: I did find one example of a New Jersey government agency suing Youtube for a copyright infringement, , so I guess they're willing to protect their copyright if they want to. I'll let you interpret the article as you will, but I think it's likely that the copyright concerns were not the NJTA's chief concern in trying to get the material removed from Youtube. Buddy431 (talk) 03:44, 7 January 2011 (UTC)

Speed of gravity

If nothing escapes from a black hole,how does gravity which also travels at the speed of light?02:09, 7 January 2011 (UTC)118.208.93.193 (talk)

John Cowell

Although perturbations to the curvature of spacetime, i.e., gravitational waves, are thought to travel at the speed of light, the curvature of spacetime in the vicinity of a black hole is in a steady state. As physicists say, "black holes have no hair". There's no gravitational information to escape. Red Act (talk) 02:18, 7 January 2011 (UTC)

And the gravity field starts before the black hole is formed, and perhaps the black hold never forms in the reference frame of those outside it. Graeme Bartlett (talk) 07:58, 7 January 2011 (UTC)

Alan Guth's inflation period.

If matter,time and space were created in the big bang and Alan Guth claimed everthing accelerated beyond the speed of light then; What force accelerated it? What did it expand into? If it exceeded the speed of light then it would be travelling into a past that never existed, What FTL force decelerated it.

John Cowell118.208.93.193 (talk) 02:30, 7 January 2011 (UTC)

The expansion of the universe is not the result of a force moving matter around. It's not the objects themselves moving. It is the actual space itself being created. See Metric expansion of space. There's nothing pushing because matter itself isn't being moved. It's the space between the bits of matter that is getting bigger. And space, lacking a mass, requires no force to make it accelerate. --Jayron32 02:40, 7 January 2011 (UTC)

Nothing has really accelerated to a speed greater than the speed of light (c). The rate at which the distance between very distant objects increases can be a faster rate than c, but that's because the space itself is growing, not because any objects are moving faster than c within space. All objects are locally traveling at a speed less than c, as measured in any (local) inertial frame of reference. Red Act (talk) 04:04, 7 January 2011 (UTC)

The balloon example is often used to explain this (and to make physics students cringe at the absurd oversimplification of the example). Blow up a balloon. Place two dots on the outside of the balloon. Those are two points in space. By law, nothing can travel across the outside the balloon faster than a certain speed (c). All is well. Now, blow up the balloon some more. The dots move apart, from your perspective of looking at the whole balloon, but from the view of the points, they haven't moved at all. So, the speed limit wasn't affected by blowing up the balloon. Continuing, you can blow up the balloon faster than the speed limit, making the two points move away from each other faster than c. From your point of view of looking at the whole balloon, they are breaking the speed limit, but they aren't really. The speed limit states that nothing can travel across the surface of the balloon faster than c. The two points aren't moving at all from their perspective. All in all, it is has to do with what the speed is relative to - hence relativity. With that understanding, you can see how a person can say that the dots on the balloon are expanding faster than c, but they aren't actually moving at all. So, there is no concept of force involved. Therefore, asking what force moved them is missing the point of the expansion theory. -- kainaw™ 14:40, 7 January 2011 (UTC)

At what temperature does the volume of water decrease, regardless of whether your increase or decrease the temperature?

Assuming 1 atmosphere of pressure.--70.122.125.20 (talk) 03:23, 7 January 2011 (UTC)

See Properties_of_water#Density_of_water_and_ice. Its right in the first paragraph, and in the chart at the right. --Jayron32 03:40, 7 January 2011 (UTC)

You are really just asking the temperature at which water has the minimum density (at 1 atmosphere), right ? StuRat (talk) 04:00, 7 January 2011 (UTC)

Maybe I'm misreading - but there is no temperature where the volume decreases when the water is either warmed or cooled. At 4 celcius, the density will decrease in either direction on the temperature scale; volume will increase. Nimur (talk) 04:02, 7 January 2011 (UTC)

Ah. That is what he said. In that case liquid water has a minimum density at the boiling point. Gaseous water has no minimum density, due to the fundemental nature of gases. Solid water (ice) has numerous allotropic forms, each with their own behavior in regards to temperature, so its difficult to answer. --Jayron32 04:08, 7 January 2011 (UTC)

Liquid water at 100°C isn't a right answer, though, because if you increase the water's temperature a bit, it will turn to gas, and the water's volume will increase.

The question specifies a pressure of 1 ATM. If you freeze liquid water at 1 ATM, it will form ice I_h (normal ice). Normal ice at 0°C has a density that's at a local minimum (volume at a local maximum), because if you increase its temperature a little, it will turn into liquid water and shrink, but if you cool the ice, it will also shrink (see Ice#Characteristics). Red Act (talk) 05:02, 7 January 2011 (UTC)

ball bearing

what kind of link a ball bearing forms(a turning pair,a spherical pair etc..,what?). i know its higher pair. —Preceding unsigned comment added by 115.248.161.154 (talk) 04:27, 7 January 2011 (UTC)

It's called a rolling pair. Red Act (talk) 06:36, 7 January 2011 (UTC)

gravitational acceleration

what is the relation between gravitational acceleration and gravitational constant? — Preceding unsigned comment added by Dev follower of maths (talk • contribs) 08:27, 7 January 2011 (UTC)

We have articles on Gravitational constant (denoted G) and Gravitational acceleration (usually denoted g), and the approximate relationship (ignoring rotational effects) is

g = GM/R (where M is the mass of the earth, and R is its radius). The second article explains the subtleties. Dbfirs 09:54, 7 January 2011 (UTC)

electronics

describe of ac and dc? — Preceding unsigned comment added by Dev follower of maths (talk • contribs) 08:28, 7 January 2011 (UTC)

The articles on Alternating current and Direct current should answer your question (basically DC is electricity that flows one way, whereas AC changes direction), but please come back to ask again if you don't understand them. Dbfirs 09:59, 7 January 2011 (UTC)

Ceramic flat iron

Can someone explain to me how,infrared ceramic flat irons work? I bought one in Europe and it makes a humming noise but no detectable "heat" the brand is ASCET...the iron came with no instructions............. —Preceding unsigned comment added by 24.127.222.196 (talk) 10:15, 7 January 2011 (UTC)

Are you using it on the recommended supply voltage (i.e presumably the same as the country in which you bought it)? If not, it will never work.--Shantavira| 12:09, 7 January 2011 (UTC)

...or at least not work well. Europe has (nearly?) universal 230V/50Hz. The US has 120 V. As a consequence, unless there is a universal power supply, a simple heating element will dissipate about 1/4 of the expected power on a US mains outlet as opposed to a European one - it might become warm, but very probably not hot. And if it has more complex electronic components, it will probably not work at all. --Stephan Schulz (talk) 12:46, 7 January 2011 (UTC)

Removing a mole

To remove a mole, put a hose down it's hole and fill with water. :-) StuRat (talk) 19:10, 7 January 2011 (UTC)

Those who do not write well do not read well. Cuddlyable3 (talk) 01:42, 8 January 2011 (UTC)

Cuddlyable3 vs. It's; 2011 court case. --Chemicalinterest (talk) 14:10, 8 January 2011 (UTC)

Ha! I see you also followed the Internet Spelling Flame Rules, in that your comment itself contains a speling mistake:) Court cases are "X v. Y" not "vs.". DMacks (talk) 18:34, 8 January 2011 (UTC)

The loneliest thing in the universe

Hello,

Imagine a lone elementary particle which is so far away from everything else that it interacts with nothing and is beyond the reach of any force. What effects would this total release from outside influence have on properties such as charge, spin, etc.? To what extent does interaction with the elementary forces shape the properties of elementary particles?

I know we couldn't observe such a particle if it existed, I just want to know what the theory tells us. Thank you. Leptictidium (mt) 12:33, 7 January 2011 (UTC)

There are no particles within the observable universe which aren't effectively gravitationally and electromagnetically bound to other particles to some extent. The ratio of leptons such as photons to baryons is just too large for a person to meaningfully comprehend. Light from other galaxies is visible to the naked eye. 71.198.176.22 (talk) 13:51, 7 January 2011 (UTC)

This is a "What sound does a falling tree make when nobody is listening?" type of question, isn't it? Any physical measurement requires interaction. As soon as we try to measure the charge, spin, etc. we have to interact with the particle, and therefore we cannot answer your question by measurement. I don't think any theory would predict anything other than that the particle has the charge, spin, etc. appropriate for its type. Anyhow, whatever a theory says, it would be an untestable, therefore from a scientific viewpoint useless, statement. --Wrongfilter (talk) 14:02, 7 January 2011 (UTC)

If such things amuse you, you may look up Mach's take on the bucket argument. Beware, however, that Mach's position on this is nowadays considered to be wrong. Einstein, among others, tried hard to find a way in which it could be right, but with no success. –Henning Makholm (talk) 15:48, 7 January 2011 (UTC)

Holy shit! That bucket argument was what I tried to ask my physics teacher 10 years ago, and they stared at me blankly! Just so I'm clear, is Einstein's position that, if the bucket of water were the only thing in the universe, the water would still have a concave surface because it is rotating relative to the geodesic formed by the mass of the water and bucket? Or is his position that it couldn't be said to be spinning at all, and thus the water would be flat (although I suppose the water might be convex if the only gravity is the water and the bucket, but the question remains of whether it would experience centrifugal 'force')? Perhaps rephrased as 'if a gaseous planet were the only thing in the universe, can it be said to spin, and would it therefore bulge?' And is the situation of a real gas giant bulging said to be because it is spinning relative to the gravity fields of everything else in the observable Universe? Would it bulge less if the Universe were smaller in terms of mass? <sorry if this is threadjacking: I got overexcited. Should I start a subsection? 82.24.248.137 (talk) 22:56, 7 January 2011 (UTC)

Einstein and modern science in general (and the General Theory of Relativity in particular) say, unambiguously, that a rotating gas giant in an otherwise empty universe would bulge. Space itself knows what "non-rotating" means; it is an absolute -- in stark contrast to "non-moving", which has no inherent meaning except relative to a particular frame of reference.

What Einstein felt, on philosophical grounds that he attributed to Mach, is that it ought not be so -- that the universe would be a beautifuller place if it were governed by a theory where "non-rotating" doesn't need to be a built-in primitive property of space. But he never succeeded in constructing such a theory, and neither has anyone else. –Henning Makholm (talk) 02:39, 8 January 2011 (UTC)

For an actual answer, we can look at the Schrodinger Equation. One of the first exercises in a quantum mechanics course is to take a lone particle in empty space, as you describe, and watch it evolve in time. Basically the particle, without anything to constrain it, expands out into the void. It becomes everywhere and nowhere until it has some constraint, something with which it can interact. If you know some mathematics, picture a Normal Distribution that just gets infinitely wider. The particle is there, but found anywhere with equal probability - it will "stick" to whatever it can find, but if alone it will be without definition forever.

When you expand the situation to include Quantum Field Theory, you get vacuum fluctuations which spontaneously appear and are able to localize the particle. To me, this is the most intuitive aspect from which to "trust" quantum mechanics: the void is equally nothing and anything, for if it were entirely nothing, then the universe is a contradiction. SamuelRiv (talk) 20:39, 7 January 2011 (UTC)

Primordial black hole evaporation as gamma ray bursts

The Primordial black hole article says, "The evaporation of primordial black holes has been suggested as one possible explanation for gamma ray bursts. This explanation is, however, considered unlikely."

That's what I want to know: By whom? And why is it considered unlikely? Gamma-ray burst#Progenitors cites Cline, D.B. (1996). "Primordial black-hole evaporation and the quark-gluon phase transition". Nuclear Physics A 610: 500.... as supporting the possibility, but doesn't say what the evidence against it might be. The "Related Articles" on that cite include , , , and , which don't seem to discount the possibility either. Why is it unlikely? 71.198.176.22 (talk) 13:42, 7 January 2011 (UTC)

A disappearing black hole should give a burst that rapidly rises in strenght and then suddenly stops, where as the burst actually appear to be steady. Also the optical counterparts look like supernovas, you would not expect to see much from a black hole evaporation from a long distance. And finally you have the energy levels involved, the black hole releases far less energy than a supernova and would not be observable half way across the universe. Graeme Bartlett (talk) 22:58, 7 January 2011 (UTC)

Relativity

If time is relative, and speed is relative, then what about size, shape, and distance? —Preceding unsigned comment added by 165.212.189.187 (talk) 14:37, 7 January 2011 (UTC)

In a nutshell: yes, because if time and speed are relative, it affects how you measure length in profound ways. See Length contraction for the full discussion. ("Shape" is only a "yes" if you mean the general dimensions of something, not "it's a square no wait it's a circle." Ditto "size.") So two observers traveling in different reference frames will disagree on the length of space and length of objects in rather striking ways. The Ladder paradox illustrates this rather vividly. --Mr.98 (talk) 14:58, 7 January 2011 (UTC)

Please explain what you typed in parentheses. shape is either yes or no. I mean square vs. circle, duh. —Preceding unsigned comment added by 165.212.189.187 (talk) 15:43, 7 January 2011 (UTC)

An intrinsically circular object will be seen measured as being elliptical in a coordinate system that moves with respect to it. Incidentally, the theory of relativity is more concerned with absolutes or invariants rather than relative (coordinate-dependent) things, and Einstein himself later regretted the name he had given to his theory (I don't have a quotation right now). I struck out "seen" because miraculously an individual observer always perceives a sphere as a sphere albeit rotated. --Wrongfilter (talk) 16:09, 7 January 2011 (UTC)

I've forgotten most of the relativity that I ever knew (and that wasn't much) but I thought that the relative view was effectively a rotation (as mentioned by Wrongfilter), so that a rod viewed from the side would appear shorter, but a sphere would maintain its "apparent shape" , and a cube would appear rotated with the trailing side being visible when it "shouldn't be". What would one "measure" to record an ellipse? Dbfirs 17:57, 7 January 2011 (UTC)

... (later) Oh, yes, I "see", one would measure the distance between two marks on the original sphere at opposite ends of the diameter along the direction of motion in its rest-frame. If the moving sphere had its "pole" pointing towards the observer, and had a circle painted round the equator, the observer would see this circle as an ellipse only if the sphere was transparent, otherwise part of it would be hidden. Is this correct? Dbfirs 17:59, 7 January 2011 (UTC)

Well, measuring means taking the coordinates of various points simultaneously (in your rest frame). Imagine placing two rulers in the path of the moving sphere, one aligned with its direction of motion, the other perpendicular. Then mark simultaneously (in your restframe) the points where opposite sides of the sphere are on those rulers. The marked length in the direction of motion will be shorter than that perpendicular to it. If you trace out a cross-section of the sphere, it will be an ellipse. "Seeing" means perception by an individual observer. Consider two photons that hit your retina at the same time, one from the near side, one from the far side of the sphere. The latter photon will have travelled a longer distance, hence it was emitted earlier than the former one. In fact, it will have been emitted when the sphere was actually farther away. Taking the light travel time into account returns the ellpsoid to a sphere. --Wrongfilter (talk) 18:29, 7 January 2011 (UTC)

What I'm worried about is what you mean by "opposite sides of the sphere". Is that "opposite ends of a diameter in its own rest-frame", or opposite ends as the observer "sees" it. I think these would be different. Dbfirs 08:18, 8 January 2011 (UTC)

What about SIZE??? —Preceding unsigned comment added by 165.212.189.187 (talk) 21:21, 7 January 2011 (UTC)

Since no-one else has replied, I'll venture an inexpert opinion that it depends on what you mean by "size". In its own rest-frame, an object's dimensions do not change with speed, so size is unchanged. In an inertial frame that is moving at speed with respect to the object, the dimension along the direction of the speed appears contracted, but is "actually just rotated". If the observer measures just that dimension then it seems to be reduced in "size", but if the observer "looks" and interprets what he "sees", then the moving object will just appear the be the same "size" of object, but rotated. One interpretation of this might be that "size" and "shape" have not changed, but that "orientation" has changed. Distance perpendicular to the direction of motion is unchanged in any interpretation. As pointed out by Wrongfilter above, there is a difference between "seeing" and measuring just one dimension. Perhaps an expert can comment on my "actually just rotated" interpretation. Dbfirs 10:14, 9 January 2011 (UTC)

Microwave oven flavor transfer

If someone heats up a spicy dish of food in a Microwave oven, and seconds after it is removed a cup of water is placed inside, (let's assume for the purposes of making tea or other hot beverage), could the water in the cup possibly obtain any of the characteristics of the flavors of the food previously heated? Could the water take on the smell or taste of the food? 10draftsdeep (talk) 16:42, 7 January 2011 (UTC)

Absolutely. Heating increases the rate of evaporation of any substance; so the microwave, after heating food, will likely have a non-trivial amount of smellable and/or tastable compounds in the air. The water that follows your burrito into the microwave can certainly collect some of these compounds. --Jayron32 16:50, 7 January 2011 (UTC)

(Edit Conflict) This seems to me, as a frequent microwave user, entirely possible and indeed likely, though not due to any mysterious properties of microwave ovens as such.

When one heats food in a microwave oven it becomes filled with water vapour laden with the odours of the food, some of which (depending on the efficiency of its ventilation system) both remains in the oven's air and is deposited as condensation on its inside walls. If one immediately afterwards places and heats a cup of water in that oven, it is quite likely that enough of that 'flavoured' vapour, both from the air and revaporised from the walls, will mix into the water so as to leave a detectable taint. I must confess I haven't experienced this, but only because I usually boil a kettle for my (often concurrent) tea or coffee (though I sometimes reheat an undrunk, cold cup in the microwave). On the rare occasions when I heat a meal's second course (a steamed pudding, say) in the same microwave, I usually try first to disperse/remove (by mopping condensation) as much as possible of the previous course's 'residue' precisely so as to prevent such taste taints. 87.81.230.195 (talk) 17:07, 7 January 2011 (UTC)

It's critical to dispel the myth that evaporation produces 100.0% pure steam. Even in professional grade distillation apparatuses, the evaporation process can create a vapor that may contain evaporated residues, or even solid particulate matter, from any compound that was dissolved in the water. I'm surprised we don't have a vapor transport article; it's a redirect to a related article. Nimur (talk) 19:57, 7 January 2011 (UTC)

It also bears reminding people that if you can smell it, it is in the air. If it is in the air, it can come back out again. --Jayron32 20:25, 7 January 2011 (UTC)

Definition of life

I was reading the "life" page on wikipedia. and the first definition of life seemed a little confusing:"systems that tend to respond to changes in their environment, and inside themselves, in such a way as to promote their own continuation." because every closed system containing chemical substances that are in a chemical equilibrium respond to the changes the same way (acording to Le chatelier principle) I know that life is not a closed system. but is this definition correct? can we say that such behaviors in living organisms is because of the chemical equilibriums in them? — Preceding unsigned comment added by Sina-chemo (talk • contribs) 20:06, 7 January 2011 (UTC)

You aren't alone in being confused. Defining life is a very fuzzy thing. It actually isn't that easy to do. For every actual written definition of life I have ever seen, there exists some obviously non-living thing which can be shown to meet it. It becomes especially tricky to define life when it comes to looking at the border cases, such as viruses and prions. --Jayron32 20:23, 7 January 2011 (UTC)

Keep in mind that in the Life article, it says: "Since there is no unequivocal definition of life, the current understanding is descriptive, where life is a characteristic of organisms that exhibit all or most of the following phenomena:..." Each of the phenomena can describe something non-living, it's the collection of phenomena that is used to define life. -- JSBillings 20:42, 7 January 2011 (UTC)

Also, the spectrum of definition ranges from mainstream biology, where the definition is a lot easier ("koala = alive, rock = not alive"); to extremophile biology (where the definition is much more complicated and requires detailed analysis of biochemistry); to the borderlines of current scientific knowledge (SETI and artificial intelligence both make efforts to scientifically define "life", sometimes coming up with something that could include astrophysical phenomena, sophisticated machinery, computer software, and so on); and at some point, we go off the deep end into fringe science and eventually "religion." (If they exist, is a "God" alive? And ghosts? Pseudoscientists actually suffer seriously from a lack of definition - which lends to the enormous gaping holes in their thought-process). Within any particular realm, the community will develop an operational definition. Most mainstream biologists use a few chemical indicators and particularly rely on the concept of tropic response, which can be more concretely defined (see the list at the bottom of our article). Nimur (talk) 21:17, 7 January 2011 (UTC)

Stuart Kauffman has written about abiogenesis via auto catalytic sets of chemical species. In short, properties similar to homeostasis can be exhibited by non-living things, and he argues that non-life can transition to life in this manner (See his book "At home in the universe" for an accessible pop-sci account). However, contrary to your example, chemical systems that look similar to life are generally not equilibrium systems, but far from equilibrium Dissipative systems. Essentially, pumping energy into the system allows the formation of stable, persistent structure. In this light, my personal favorite edge case for life is the Great Red Spot. Lastly, "obviously living" organisms, such as amoebae, lizards or humans, considered chemically/thermodynamically are far-from-equilibrium, not close to equilibrium as you suggest. SemanticMantis (talk) 21:26, 7 January 2011 (UTC)

More directly to your question, Le_Chatelier_principle explains that a new equilibrium can be reached after conditions are altered. But there is a change from the old equilibrium to the new one. The only thing that persists is the notion of equilibrium, and notions can't be alive (when ideas some similar properties in common with life , we call them memes). Because the original equilibrium A disappears and a new one B is formed with different properties, no state or aspect of the system has responded to the changed conditions in a manner that preserves itself. Whatever the (modern) definition of you choose, including the one quoted in our article on life, a closed system at equilibrium will not satisfy it. SemanticMantis (talk) 23:01, 7 January 2011 (UTC)

Gould on transitional fossils

Hi guys. I have a question about evolution. Creationists seem to think that, due to political pressure, in the early 80s the late Stephen Jay Gould reversed himself on whether good examples of transitional fossils exist. Examples:

http://creation.com/punctuated-equilibrium-come-of-age

http://www.discovery.org/a/7271

I should be candid: I suspect that they have a point. I cannot see how Gould’s earlier statements to the effect that “transitions between major groups are characteristically abrupt” can be reconciled with later claims that “transitional forms are generally lacking at the species level, but they are abundant between larger groups.” If Gould reversed himself on the status of transitional forms, the perennial charge that creationists “quote mined” his views seems a little silly.

What I’m asking is if anyone knows some scientific context that I’m missing here. Does “major groups” mean the same thing in both quotes? Before c~1980, did Gould ever clearly say that transitional forms or fossils exist, or cite some specific examples? I glanced through Gould’s papers from 1972 and 1977 but I’m afraid that they’re a bit too far over my head for me to be certain of their meaning.

I’m not a creationist and I’m not asking anyone to “argue me out” of creationism.

However, for my education, I would appreciate if anyone can point out something that I’ve missed.173.13.48.54 (talk) 20:07, 7 January 2011 (UTC)

I think that the above statements are, like most arguements out of the creationist camps, based on overanalyzing a tiny amount of data while ignoring the abundance of the rest of the data. I don't see the statements as contradictory at all. He says "transitions are abrupt" in the first one, but "transitional forms" in the second one, without defining how long is "abrupt". Transitions can be abrupt, but not so abrupt as to leave zero evidence. Also, science and scientists DO change their opinions about things over time. This is how science works. Perhaps Gould's earlier theories on punctuated equilibrium became more refined over time as new evidence became availible. That isn't a contradiction; its a refinement of the existing theory. I'm not sure which interpretation of Gould's statements is correct, but there are two alternate interpretations to the creationist one. Furthermore, you could just say "Come on, its two sentances made from a man who published enough works to fill a small library. Taking two statements, out of context, and attempting to "prove" that Gould somehow based his scientific pronouncements on "political pressure" rather than sound science is complete and utter bullshit. --Jayron32 20:16, 7 January 2011 (UTC)

Furthermore, it also represents a fundemental flaw in the creationist strategy. Rather than reading Gould with an open mind, and lacking any preconceived notions, and then try to work out what he means and if it makes sense, the "contradiction" claim starts from the premise that Gould MUST be wrong, and if we dig hard enough we can find evidence to support that. And THIS evidence was the best they could come up with to verify their preconceived conclusions. That should tell you something. That doesn't mean that everything Gould ever published or ever had to say about evolution should turn out to be 100% correct. That isn't how science works either. Gould may have been wrong on some of his stuff. That doesn't mean that everything about evolution is just "made up" or "completely wrong". --Jayron32 20:20, 7 January 2011 (UTC)

I think Jayron's point about punctuated equilibrium is probably the germane one. Gould was the primary promoter of PE as an explanation for the gaps within the fossil record; my understanding of the situation is that most other evolutionary theorists didn't so much disagree with it as think he and Eldredge were putting more emphasis on it than they should (and, of course, many people simply thought it was a rewording of various other hypotheses - as our article goes into in some detail). As he became more and more the public figure in the case against creationism, I imagine Gould found himself in an uncomfortable position: any weakening of his support for PE would be used as fodder by the creationists to say that he was admitting that his understanding of evolution was wrong. It's tough enough to admit that you've mis-stated something or changed your opinion on something you used to promote, but it becomes extremely sticky when you know beforehand that your relatively minor change in evaluation will get turned into something completely other by professional liars. I've read a good bit of Gould's stuff (though it's been a while) and it's my impression (WP:OR alert) that, as evidence and support began to shift away from PE into a more gradualist view, Gould's popular writing at least began focusing on slightly different topics (the relationship of science to religion, his Full House book, etc.), perhaps as a way of avoiding (or at least downplaying) the issue. Matt Deres (talk) 20:35, 7 January 2011 (UTC)

I will note that the first quote doesn't include anything like its full context; even ignoring the rest of the document, it is illuminating to read the entire sentence from which the fragment was extracted. "All paleontologists know that the fossil record contains precious little in the way of intermediate forms; transitions between major groups are characteristically abrupt."

Note that he does not state that transitional forms are unheard of or nonexistent in the fossil record, only that they are rare. This would be exactly what is predicted under punctuated equilibrium. Pulling some plausible-sounding numbers out of thin air, let's suppose that 0.1% of fossils are the remains of transitional forms; that's just one out of every thousand fossils, certainly qualifying as "precious little". On the other hand, if paleontologists have collected and fully characterized a million different sets of fossilized remains, you'd still expect to find a full thousand transitional forms in the collection: "abundant" in terms of absolute number.

One could make a similar set of statements about diamonds. They're certainly quite rare; odds are that if you pick up a random rock, it won't turn out to be a diamond. Nevertheless, they're abundant — thousands are traded every day in New York and Amsterdam, and you can see dozens of examples in most jewellery stores. TenOfAllTrades(talk) 21:21, 7 January 2011 (UTC)

Yeah, but diamonds exist because God put them there. Checkmate, atheists!. TomorrowTime (talk) 23:35, 7 January 2011 (UTC)

It would be an interesting undergraduate research paper to try and ferret out the change in Gould's thinking. I think calling it "reversing" and impugning it as somehow meaning he is unreliable is clearly wrong. We stress different aspects of our arguments to different audiences, because we assume different things about what they know and how they will interpret our work. To other specialists, we emphasize the novelty of our own small tweaks (e.g. Gould arguing for PE as a preferred model over gradualism, all within the framework of Darwinian evolution); to a broader public, we try to make sure that our in-discipline arguments don't detract from larger understandings (e.g. Gould emphasizing that PE does not mean that there aren't transitional forms, or that Darwinism is wrong). These two statements of Gould's are not incompatible if you take the purpose of their broader context into account, but I think it's clear that in the later articles, Gould is really trying to debunk any notion that PE opposes Darwinism. I wouldn't call that a reversal, so much as, er, an evolution in his expression. I doubt his underlying opinions changed too much. But it would be interesting to actually track this down historically. --Mr.98 (talk) 01:10, 8 January 2011 (UTC)

One thing to bear in mind is that the form of a species may not be free to vary as much as the underlying genetics - two recognizable forms may exist that are functional, but the intermediates between them fail badly. This is best seen in a spatial distribution - hybrid zones - you can have a butterfly which mimics one group of species, or another very different group of species, but those intermediates get eaten, so they take up only a rather small band of territory - and outside the bands, the two forms don't get more and more extreme as you move away. This is maintained actively by selection, and presumably also by genetic mechanisms that tend to stabilize certain phenotypes (heat shock proteins are known for that). The same could happen over the course of time, with selection forcing a species first to resemble one standard appearance and then a different one. Wnt (talk) 06:46, 8 January 2011 (UTC)

January 8

Gravity/Conciousness

It has been suggested that the incredible weakness of gravity compared with the other forces is because gravity is the only force which mainly resides in the other dimensions postulated by string theory.Is it conceivable that thought/afterlife/conciousness act similarly as gravity waves, like thought waves, have yet to be detected.

John Cowell.00:28, 8 January 2011 (UTC)= —Preceding unsigned comment added by 118.208.93.193 (talk)

Certainly it's conceivable: you've just conceived it. Whether it has any merit as a scientific theory is another matter. I am not aware of any evidence that thought, whatever it might be, has any properties in common with any of the fundamental forces of nature or the waves that mediate them. --ColinFine (talk) 00:54, 8 January 2011 (UTC)

Roger Penrose believes that there is an important relationship between consciousness and quantum gravity. The idea strikes me as kind of silly, but it has received a certain amount of attention, or perhaps notoriety is a better word. Looie496 (talk) 01:04, 8 January 2011 (UTC)

Yes, but Penrose does not claim that he has actual evidence for that hunch. (His metaphysical ideas are controversial, whereas his actual science is acknowledged by everyone to be solid -- and he seems to be perfectly aware of and candid about which is which). –Henning Makholm (talk) 03:00, 8 January 2011 (UTC)

It strikes me that the burden of proof is that on those who would claim that consciousness is anything more than something materialistic. The brain seems to be a fairly modular thing — there's a strict movement "upwards towards consciousness" (metaphorically, of course) moving from less-to-more complicated brains (lizards, dogs, dolphins, chimps, humans, etc.). This strongly seems to suggest that consciousness is "simply" a very complicated function of a very complicated set of neural wirings. Why one would want to introduce extra dimensions into the equation (other than the desire to not simply be a blot of matter, doomed for a finite amount of time) seems, from a scientific standpoint, fairly unclear. It doesn't mean it isn't possible. But does a lizard have the same physical hardware that you are postulating? Does a dog? Does a housefly? Does an amoeba? Does a virus? And if not, why would humans have it, and no others? Where does it start, and where would it stop? It just doesn't really seem, a priori, to be a very compelling theory, at least to me. It seems far more likely that what we call consciousness is just a measure of specialized computational organs/circuits/what-have-you within the forebrain brain. Circuits we do not at all fully understand, to be sure, but I think we're starting to get close to a general model of things, and it doesn't include anything like you're suggesting. --Mr.98 (talk) 03:43, 8 January 2011 (UTC)

I'm reading the question as discussing gravity just as an initial example of something the OP has heard may also exist "in other dimensions" according to "string theory".

The actual question is then: could consciousness exist in other spatial dimensions, and if so could our sense of consciousness in this 3-space be in some meaningful way "connected" to corresponding consciousnesses in other sets of spatial dimensions?

If I'm interpreting that correctly, then I'd have to say "maybe". I don't know enough about strings and Mbranes and whatever else to know whether in the various theories about them, it is possible for an elementary particle in our 3-space to be a manifestation of a multidimensional vibration that also manifests as "corresponding" elementary particles in other N-spaces. If so, then perhaps the particles making up our brains are mapped onto various other "brains" (including whatever higher-than-3-dimensional corresponding structures might be called). Maybe the complexity of how those vibrations/string/particles are organized in each of those other spaces also produces a consciousness that corresponds to our consciousness in this world.

That would be kind of spooky, wouldn't it be? :) I don't have an answer as to how likely anything like that might be, though – and, remember, "string theory" is still all just a mathematical framework with no empirical support whatsoever or any likelihood of there being any anytime soon, either, afaik. So even if this kind of thing were supported by theory, there would still be little reason to believe it is anything like that in Reality. WikiDao ☯ 04:38, 8 January 2011 (UTC)

The OP may be interested in Leibniz's Monad theory. Like Penrose, Leibniz had some interesting thoughts regarding consciousness and physics. Also like Penrose, Leibniz's scientific contributions are well respected. In the Monadology he hints that perception and consciousness may be tied to the fundamental units of matter. Or something. I don't think many people subscribe to theory of Monads these days. SemanticMantis (talk) 05:50, 8 January 2011 (UTC)

It seems to me that the fact that consciousness evolved is a pretty strong argument against the idea that it harnesses any sort of subtle as-of-yet unknown physics. Much of modern physics could have been very useful to biological entities (e.g. lasers, radio waves, ...) but organisms "naturally" using such physics completely failed to evolve anywhere in the biosphere. Why should consciousness be an exception? 83.134.178.145 (talk) 10:13, 8 January 2011 (UTC)

Still, there is something for science to explain here which, so far, it has not been able to do. There is no workable scientific description of the phenomenon of self-awareness. Everybody is aware of this because one is directly experiencing it - the division of the world between me and not-me and the sensation of being inside looking out on the rest of the universe. We believe that everyone else has this sensation only because we have it ourselves: there is no objective test to detect or measure it. If I claim my computer is self-aware there is no test to prove me wrong. If I claim that my mother is not self-aware, what test could be administered to falsify the claim? One can ask the subject if they are self-aware, but to any question I could, at least in principle, program my computer to give the same answer as given by my mother. Someone famous said this was the last great unanswered question of science. Given that we cannot even detect it, it is a little premature to ask how many dimensions it exists in. SpinningSpark 15:14, 8 January 2011 (UTC)

Presumably your mother could pass a mirror test. While by no means air-tight, many professionals would use this as evidence for self-awareness. SemanticMantis (talk) 15:46, 8 January 2011 (UTC)

She probably could, but then so could my computer with the help of a clever programmer so a positive result would not be determinant. Failure to pass the test likewise does not prove beyond doubt lack of consciousness. SpinningSpark 16:18, 8 January 2011 (UTC)

I suspect that most cognitive scientists would see this partially as a problem of definition. We treat consciousness and self-awareness as a "I know it when I see it" sort of affair. We have a very hard time articulating what we think it means in measurable terms. I suspect what we see as one phenomena is really a bundle of things running on different "circuits" in the brain. I still find, though, that there is little to make one think that a non-materialist, non-emergent solution makes any sense. The brain is one complicated piece of hardware — that's true even of far more "lesser" brains than human ones. It strikes me as essentially premature and illogical to assume that we should begin by appealing to things outside of the brain to understand it. There's plenty there that we still need to understand before we conclude that a wholly biological �answer is insufficient.

Incidentally, the computer answer doesn't disprove the original test. The only reason the computer can do it is because a self-aware being made it be able to do so. So there is self-awareness in that system — it comes from the fact that a self-aware being said, "hey, here's how we fool this test." What would be more interesting is if a computer system that was not programmed to do that specifically somehow developed that ability. That would be more akin to the biological analog. ---Mr.98 (talk) 16:52, 8 January 2011 (UTC)

Brain

Will putting things in your brain kill you? And what do FFI prions taste like? —Preceding unsigned comment added by 203.96.12.131 (talk) 04:13, 8 January 2011 (UTC)

(1) Not necessarily, but it will void your warranty. (2) Chicken. –Henning Makholm (talk) 04:38, 8 January 2011 (UTC)

(1) ... as a side note, despite many attempts, I have never been able to contact customer service; so I suspect the warranty is ineffectual anyway --Senra (Talk) 18:14, 8 January 2011 (UTC)

Depends. A brain surgeon could probably put something in there without doing too much damage. This is occasionally done. Microchips and such. See Neural implant.

If you're just talking about shoving something in there, then sure, there's a serious danger. But even so, some people survive it. See Phineas Gage!

Finally, I doubt you'd ever get enough prions together in one place to actually be able to taste them. APL (talk) 05:01, 8 January 2011 (UTC)

Putting in a couple of working neurons might help some people. Prions taste of nothing but they smell of troll. Caesar's Daddy (talk) 07:42, 8 January 2011 (UTC)

Reading Misplaced Pages puts thoughts in my brain. It hasn't killed me yet. Gandalf61 (talk) 07:56, 8 January 2011 (UTC)

At the risk of giving medical advice, please don't put physical objects into your brain. It's much more likely than not to harm you, and even small brain lesions can in fact lead to death depending on their location. Prions don't likely have any discernible flavor. 71.198.176.22 (talk) 16:30, 8 January 2011 (UTC)

It's very easy to put something in the brain without killing someone: see lobotomy. That being said, it's fairly difficult to put something in the brain without appreciably damaging it, and probably requires a medical degree to do so on a regular basis (it literally is brain surgery, after all). Buddy431 (talk) 22:50, 8 January 2011 (UTC)

Motor

First motor invented or generator invented becoz I heared the motor was the first am I right? — Preceding unsigned comment added by Kanniyappan (talk • contribs) 11:14, 8 January 2011 (UTC)

Yes. Dynamo says "The first electric generator was invented by Michael Faraday in 1831". It then apparently contradicts itself by mentioning Jedlik's dynamo, 1827. Electric_motor#History_and_development says Faraday invented a mercury motor (which does no useful work) in 1821. I don't know if he was the first to make such a thing, and technically every motor can be used in reverse as a generator, but pushing the wire around in circles in an attempt to generate current sounds difficult, so assuming nobody made any higher-tech motor before Jedlik's dynamo, the motor came first. 213.122.7.185 (talk) 14:53, 8 January 2011 (UTC)

A partisan advocate of Jedlik introduced many dubious claims based on sources in Hungarian. 19th century histories of motors and generators (in English) only credited Jedlik with some dynamo improvements much, much later than the claims in the Misplaced Pages articles about Jedlik, motors, and dynamos. We need someone able to read Hungarian to clarify what the sources actually say. Edison (talk) 20:30, 8 January 2011 (UTC)

If you consider a steam engine to be a motor, then they go all the way back to Hero's engine. StuRat (talk) 14:55, 8 January 2011 (UTC)

Cosmology

I recently heard of an idea: an explosion so massive, that it sends shockwaves through space-time. At subluminal speeds, an observer should be able to see a wave front of Lorentz and time contraction, followed by dilation of both kinds. Is this a plausible idea? --Plasmic Physics (talk) 11:37, 8 January 2011 (UTC)

Not exactly, but gravitational waves come close. The largest difference from your description is that gravitational waves are supposed to propagate at lightspeed, and that they cannot (as a matter of GR mathemathics) be exactly spherically symmetric, so they wouldn't be generated by a symmetric explosion however massive. –Henning Makholm (talk) 12:51, 8 January 2011 (UTC)

What should create notable gravitational waves, what should the intensity be proportional to? --Plasmic Physics (talk) 22:24, 8 January 2011 (UTC)

Faking carbon/radioactive decay

This is a bit of a complicated question relating to carbon dating and radiometric dating.

Carbon dating is useful for finding the age of relatively recent fossils. The carbon-14 begins to decay, and around 5700 years or so, it's half replaced with nitrogen-14. Every 5700 years (the "half-life" of carbon-14), half the remainder decays. We can measure around how old the fossil is by comparing the amount of carbon-14 to nitrogen-14.

What I was curious about is, would someone be actually able to change the amount of either carbon-14 or nitrogen-14 in the fossil? Is such a process possible?

Of course, carbon dating only works to about 100,000 years ago. For older fossils or actual rocks, you use radiometric dating (as I think it's called). Let's say this mineral is full of uranium-235. After about 700 million years, it's half replaced with lead-207. So 700mya is the half-life of uranium-235. After another 700mya, another half of the uranium-235 has been replaced with the lead-207, and so on. Would it be possible to remove or add bits of either the uranium-235 or the lead-207, like I suggested with the carbon-14 and nitrogen-14?

Please note, I'm not suggesting to actually fake fossils and minerals in this way. That would be bad...but is it possible? Crimsonraptor | (Contact me) Dumpster dive if you must 15:00, 8 January 2011 (UTC)

All forms of radiometric dating (of which carbon-14 and uranium series dating are two of several examples) are subject to errors from contamination, sediment mixing in fossils, and other sources of incidental, accidental, and systematic errors. That is why most radiochemists prefer to date from as many sources of information as possible to cross-check. Intentional contamination seems fairly difficult to me, however. If you're a paleontologist who wanted to pass off a fossil as older or younger than its radiometric age, you might be able to guess about which part of the fossil to contaminate, but I'm not sure how good such a guess could be, or whether such tampering wouldn't be obvious or at least make the radiochemist sample from a different part of the fossil. Other less sophisticated forms of scientific fraud (misreporting measurements, for example) are much more common. 71.198.176.22 (talk) 15:48, 8 January 2011 (UTC)

You would need to replace a portion of the fossil with something of a different age. If you knew in advance the exact location where the sample would be taken, this could be done (although making it look right would be tricky). Otherwise, you might have to replace the entire fossil. StuRat (talk) 15:51, 8 January 2011 (UTC)

OK, so you'd have to change the actual material itself, not the stuff in the material? Crimsonraptor | (Contact me) Dumpster dive if you must 15:55, 8 January 2011 (UTC)

Yes, because the fossil and surrounding material has to be removed as a sample and pulverized to extract the daughter isotopes of interest. The sort of tampering you're contemplating here might very well be more difficult than fabricating an entire fossil from scratch (which has happened at least a few times in the history of scientific frauds. In the art world this kind of deception would be much easier, because owners of valuable art can restrict chemists from sampling all but certain portions of the work in order to prevent it from being disturbed in a detectable fashion. That allows forgers more leeway.) 71.198.176.22 (talk) 16:19, 8 January 2011 (UTC)

Most radiometric dating methods would not be able to date the fossil directly anyway. The sequence of rocks containing the fossils can be dated by working out the age of lavas or ash layers interbedded with the sedimentary rock e.g.. It would be simpler just to claim a fossil find from the wrong part of the sequence, but no-one would accept that unless other examples were forthcoming. Mikenorton (talk) 16:01, 8 January 2011 (UTC)

There also is a strong difference between C-dating and most other dating methods. C dates organic material. It depends on the fact that C is created at a (fairly) fixed rate in the atmosphere, and hence is at a fairly constant level in the atmosphere. Living things are in good equilibrium with the atmosphere. In other words, we know reasonably well what percentage of carbon in living things is C. Once something dies, it essentially stops exchanging carbon with the environment. C decays. The daughter element, N, typically escapes. We determine the age of the object by looking how the C/C ratio has changed (by decay of C), without ever looking at the daughter element. Other radiometric techniques work differently. If you look at e.g. K–Ar dating, we do not know the initial amount of K. We do know, however, that the daughter element, Ar, is a gas, and will escape from molten magma, but not from crystallised rock. So we start with an unknown amount of K and zero Ar. For dating, we assume that all Ar we find is the result of the decay of K, and we can hence determine the age (of the solidification event) from the ratio of Ar to K. The nice thing about this is that we can repeat the experiment with different samples with different initial K. If the samples are the same age, and not contaminated somehow, they will all have different absolute amounts of Ar an K, but all the same ratio of them. In a diagram, the different samples all fall onto the same straight line. This property allows us to detect contamination and problems, or, in the other case, to strongly confirm the dates.--Stephan Schulz (talk) 23:56, 8 January 2011 (UTC)

Dedendum circles

"dedendum circle diameter must be less than base circle diameter then the part of profile is not involute towards lower side of base circle." is this statement right for interference of involute profiles.are not the dedendum circles same as base circle.please help. —Preceding unsigned comment added by 59.93.129.167 (talk) 15:59, 8 January 2011 (UTC)

Can you clarify your question? Our article List_of_gear_nomenclature may help you out. It only explicitly defines dedendum angle, though the graphic for addendum shows a dedendum radius. The base circle radius is not the same as the dedendum radius. The article seems to indicate that the base circle radius plus the dedendum radius would give the pitch circle, but I may be misinterpreting. SemanticMantis (talk) 16:56, 8 January 2011 (UTC)

SnCl2-Sn(OH)Cl vs. SbCl3-SbOCl conversion

At what pH do these conversions take place? I have a solution with a pH of 1.5 and there is a white precipitate that must be either of these. --Chemicalinterest (talk) 18:33, 8 January 2011 (UTC)

The exact pH will depend on the chloride concentration. pH 1.5 seems quite acid for either one, unless you're right out of chloride in the solution, but the antimony will come out before the tin does, that's for sure. Physchim62 (talk) 02:28, 9 January 2011 (UTC)

Dioxin in Germany

How and why did the Polychlorinated_dibenzodioxins contaminated food in Germany recently? Quest09 (talk) 19:13, 8 January 2011 (UTC)

A news article says "tainted fatty acids" used to make animal feed are suspected. Edison (talk) 20:26, 8 January 2011 (UTC)

yes, but why would someone taint animal feed with dioxin? If you feed hormones to a cow or chicken you make it fatter, but there is no advantage in mixing dioxin on purpose. So, why did it happen, where did it come from? Quest09 (talk) 20:40, 8 January 2011 (UTC)

It seems unlikely anyone purposely tained the animal feed (i.e. with the intention of adding dioxins) or at least there's no indication I've seen of that being the case. Various sources suggest the fatty acids were intended for industrial (not industrial food!) use only but were mixed with the fatty acids intended for animal feed. Whether this was accidentally or not doesn't seem clear but it's suggested the company knew about the high level of dioxins for a long while . This doesn't explicitly answer why the fatty acids were contaminated but the first source (provided by Edison) says it's not uncommon. Nil Einne (talk) 21:18, 8 January 2011 (UTC)

It may have been like the antifreeze-in-wine incident of the past - it made someone money. The mineral oil was probably a lot cheaper than food-grade oil. 92.15.7.205 (talk) 21:35, 8 January 2011 (UTC)

2D holographic display

In some sci fi media like anime or video games like dead space (video game) they have 2D holographic displays like this http://cdn.themis-media.com/media/global/images/galleries/display/55/55099.jpg is there any specific name for this kind of technology? Is there any real world tech working on this? All the articles on wikipedia just deal with 3D volumetric displays not 2D holograms. ScienceApe (talk) 20:04, 8 January 2011 (UTC)

You mean a 2d image projected out into thin air? I don't know if there is a general name for them. A company named Heliodisplay makes them. (They spray a thin sheet of mist into the air then project onto that.) But they're mostly just gimmick. APL (talk) 21:56, 8 January 2011 (UTC)

January 9

Why does any number muliplied by nine add up to nine?

i.e 13times 9=117. 1+1+7=9 and so on.AM radio frequencies in Australia are all multiples of nine. <e-mail address removed>, 9 January 2011 (UTC) —Preceding unsigned comment added by 118.208.93.193 (talk)

I removed your e-mail address so that you don't get unwelcome attention from spammers - any answer to your query will appear here. Mikenorton (talk) 00:29, 9 January 2011 (UTC)

They add up to nine because they don't add upto 8. See, Numerology, Apophenia, Confirmation bias, and 23 enigma. --Plasmic Physics (talk) 00:55, 9 January 2011 (UTC)

It's to do with us using base 10. If you add the digits of an number, in any base, and end up with base-1, then the original number is divisible by base-1. If you end up with a (multiple of a) factor of base-1, then the number is divisible by that factor. For example

• 123 (= 3 * 41), is 1+2+3 = 6, so 123 is divisible by 3.
• 32_hex (50 in decimal), is 3+2=5. 5 and 3 are the factors of 15 (16-1), so 50 is divisible by 5.

There should be an article on this, as WHAAOE, but I don't know what the phenomena is called. CS Miller (talk) 01:09, 9 January 2011 (UTC)

BTW, you might have been better asking on the maths desk. CS Miller (talk) 01:11, 9 January 2011 (UTC)

See Casting out nines for a related, somewhat more general phenomenon. Buddy431 (talk) 04:22, 9 January 2011 (UTC)

Let me first of all rephrase your question more clearly. "Any (positive integer) number multiplied by nine" gives you a (positive integer) number that is divisible by nine. What you asking is, why do all positive integer numbers divisible by nine have their digits, in base 10 notation, adding up to 9. Well, they don't. For example, 99=11*9, 990=110*9, 9900=1100*9, etc. are all divisible by 9, but the sum of their digits is 18. The correct statement is: "In base 10, any positive integer that is divisible by 9 has its sum-of-digits divisible by nine, as well". In the example I just gave, the number 9900 = 1100*9, the sum of digits 9+9+0+0 = 18 = 2*9. A simple, non-rigorous proof -- I am a physicist, not a mathematician :) -- is as follows. Imagine you have a number . For example, if the number is 3456, a₃ = 3, a₂ = 4, a₁ = 5, and a₀ = 6. Incidentally, 3456 = 384*9 and 3+4+5+6 = 18 = 2*9. Since we use base 10, the value of is x = 1*a₀ + 10*a₁ + ... + 10*a_n. Now, what happens when you divide by 9? Let's divide every term separately. 10*a₁ = (9+1)*a₁ so residue from this term is 1*a₁; the next term 100*a₂ = (99+1)*a₂ so residue of division of that term by 9 is 1*a₂; and so on. When you sum up all the residues you get 1*a₀ + 1*a₁ + ... + 1*a_n. This is the sum of digits of your original number! The sum of residues equals the sum of digits. So, if the sum of digits divides by 9, so does the full residue; that means the original number divides by 9, as well. --Dr Dima (talk) 02:08, 9 January 2011 (UTC)

The digital root is 9 for all positive multiples of 9. Digital root#Congruence formula mentions the generalization to b−1 for base b. PrimeHunter (talk) 02:31, 9 January 2011 (UTC)

Dr Dima in part says the sum of the digits is 18 but as for all whole numbers the digits 1+8 again add to nine.Regardless of how high the number is taken every time the result is added and re-added it wil eventually resolve to 9. I failed maths at school so please be gentle with me.

John Cowell.118.208.9.92 (talk) 03:14, 9 January 2011 (UTC)

Can you clarify your question? As you noted, the sum of the digits of any multiple of nine sum to another multiple of nine, eventually summing to nine if you do it long enough (that is, 4617's digits add to 18, and 18's digits add to 9). This is just as you stated it. — Lomn 04:09, 9 January 2011 (UTC)

Oh, OK, you're referencing this. Dr Dima is being precise about it (in base 10, integer multiple, a formal statement of "might have to repeat to reach 9", etc). — Lomn 04:12, 9 January 2011 (UTC)

See Casting out nines for a more general, related phenomenon. There's an explanation, but it's a bit dense. One thing to note: whenever you add nine to an integer, you always increase the sum of the digits by zero or by 9. Check this to see that it works out. It's intuitively not hard to see why this: if the unit's digit is zero, it becomes a nine, and the rest of the number remains unchanged (for an increase of 9 in the sum). When the last digit is any other number (1-9), the units digit decreases by one, while the Ten's digit increases by one, for a net increase of zero in the sum of the digits. Predictably, the reverse is true in subtracting nine: the sum of the digits either decreases by nine, or remains the same. Buddy431 (talk) 04:18, 9 January 2011 (UTC)

(edit conflict) This is discussed somewhat at our 9 (number) and Digital root articles, and an interesting use of this property is discussed at Casting out nines. It has to do with the fact that in base-10, 9 is the last digit before you have to start reusing digits (ie. the digits "1" and "0" in "10"). WikiDao ☯ 11:21 pm, Today (UTC−5)

When and how are 1920s–30s lighthouses lit?

I'm doing research for a painting of the lantern room of a lighthouse. I'm having difficulty finding information on how a lamp is lit and when it is lit. In the "lighthouse technology" section of the lighthouse article, it is mentioned that the Dalén light was used predominantly in the 20th century (up until the 60s), but although I followed through to the sun valve article and its external link, I'm not finding what a Dalén light actually looks like, and where a sun valve would be placed on, or within, the lighthouse. I've also found images of first and second order Fresnel lenses (from our own Commons), but not what they look like from above. Are they open at the top to allow heat to escape? (In this example, it almost looks like the answer is "no"). As a mere matter of curiosity, how "hot" was the actual beam of light—could someone stand on the gallery with their back to the lantern room while the light was rotating? Any recommendations for more information on this particular area of the lighthouse would be welcome! – Kerαunoςcopia_galaxies 01:14, 9 January 2011 (UTC)

It was an acetylene lamp, with the "solar valve" which turned it on and off based on the sun shining on the apparatus. Some results are found at Google book search such as . This appears to be a picture of the Fresnel lens and a lamp from a lighthouse, though it may be a different lamp than the Dalen. It went all around and had a vent in the top, naturally to let the combustion gases out. I did not find info on the lightintensity or heat of the lamp. Edison (talk) 02:25, 9 January 2011 (UTC)

I found this image , which is the man himself standing next to what is evidently a fresnel, though the caption says it's his sun valve, so I assume the sun valve is attached somewhere (there may even be a Dalén light in there too if you're lucky). Unfortunately I couldn't say which piece of apparatus is which. 213.122.40.179 (talk) 02:31, 9 January 2011 (UTC)

I jumped to the Swedish Misplaced Pages article on the lamp, which linked to an AGA site with some pictures. The solar valve had a bunch of rods which could heat up and turn off the gas when the sun sas shining. See (in Swedish. Google Translate is your friend). Edison (talk) 02:45, 9 January 2011 (UTC)

That clarifies the Dalén light perfectly. I was confused because I thought i would actually see it, but the fresnel lens would simply cover it up. A detailed image of the source wouldn't be visible through the lens. Thanks all! – Kerαunoςcopia_galaxies 03:04, 9 January 2011 (UTC)

T ime lapse from brain to tongue.

Any thoughts on the time it takes to make speech from the brain formulating the next word?Think Spoonerisms. John Cowell.118.208.9.92 (talk) 01:20, 9 January 2011 (UTC)

It takes perhaps a fifth of a second to voice a known prearranged response when a stimulus is presented, much like pressing a button as a simple reaction time response. If an unknown stimulus letter is presented, the vocal response time is appreciably longer, but still far less than a second. Anecdotally, if one's attention is diverted after an utterance begins, something random and funny may emerge, as if the speech generator were on autopilot and randomly choose a related but unintended word. Certainly the longest time from formulating an utterance to saying it could be many seconds, but the shortest would seem to be a fraction of a second. Mental chronometry researchers have argued for well over a century as to how to determine the time required for internal mental operations, so whether the number you seek is 200 milliseconds or 500 milliseconds or whatever would be open to debate. Edison (talk) 02:10, 9 January 2011 (UTC)

Thinking Spoonerisms maybe I could rephrase in terms of how many words ahead of the tongue is the brain?

Is English spoken more slowly than many other languages e.g.Spanish?

John Cowell.118.208.9.92 (talk) 02:40, 9 January 2011 (UTC)

electromagnetic waves

How do electromagnetic waves emit? I understand how the elctric and magnetic fields form, but I don't understand how (or why) they move forward. — Preceding unsigned comment added by Sina-chemo (talk • contribs) 09:25, 9 January 2011 (UTC)

It is a disturbance in the field that is moving, rather than the field itself. In much the same way, a disturbance on a water surface causes a wave to propagate outwards from the original disturbance without the whole body of water moving anywhere. Take a look at electromagnetic radiation and come back if you have more questions (the formal mathematical treatment is at the bottom of the article). SpinningSpark 11:46, 9 January 2011 (UTC)

circular motion

a stunt car makes horizontal circles of radius 20m along the inside surface (with an angle of elevation of 30 degrees) of a vertical cone. the coefficient of static friction between the tires and the road is 0.25. find the possible range of speeds of the car.

i've arrived at these two eqns: n cos 30 =mg+0.25nsin30 and n cos 60 + 0.25nsin60=v^2/20 cos 20. where n is the normal force. how do i continue? — Preceding unsigned comment added by Invisiblebug590 (talk • contribs) 10:17, 9 January 2011 (UTC)

What did, and will, toilets look like?

I was going to ask this on AOL Answers, but I don't think their users would've been too happy about it, so I asked here instead:

1. What did toilets look like in 1900?
2. What did toilets look like in 1910?
3. What did toilets look like in 1920?
4. What did toilets look like in 1930?
5. What did toilets look like in 1940?
6. What did toilets look like in 1950?
7. What did toilets look like in 1960?
8. What did toilets look like in 1970?
9. What did toilets look like in 1980?
10. What did toilets look like in 1990?
11. What did toilets look like in 2000?
12. What did toilets look like in 2010?
13. What will toilets look like in 2020?
14. What will toilets look like in 2030?
15. What will toilets look like in 2040?
16. What will toilets look like in 2050?
17. What will toilets look like in 2060?
18. What will toilets look like in 2070?
19. What will toilets look like in 2080?
20. What will toilets look like in 2090?
21. What will toilets look like in 2100?
22. What will toilets look like in 2110?

--70.179.178.5 (talk) 12:13, 9 January 2011 (UTC)

Why is the Washlet hard to penetrate the bathroom fixture market here in the US?

The spray toilets like the Toto Washlet are fairly common in Japan, but why are they hard to enter the market in America? I thought most decent Americans would want the utmost personal hygiene, so why are they still slow to accept the fabled spray-toilet? --70.179.178.5 (talk) 12:13, 9 January 2011 (UTC)

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