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November 18

Na₂CO₃

hello. I recently did an investigation with crystallization and am now in the process of writing my conclusion. I have been able to find the correct lattice system (monoclinic, cubic, etc.) for all of them except the above, anhydrous Na₂CO₃. Can someone help me out with regards to which of these it falls udner? Thanks. 24.92.85.35 (talk) 01:25, 18 November 2011 (UTC)

I don't know about anhydrous sodium carbonate, but the decahydrate crystalises in the monoclinic system. Plasmic Physics (talk) 01:56, 18 November 2011 (UTC)

For anhydrous sodium carbonate at normal conditions of temperature and pressure, it is monoclinic with space group C2/m, but above 760K it is hexagonal with space group P6₃/mmc.[1] Graeme Bartlett (talk) 12:42, 18 November 2011 (UTC)

"Infinite" resistance, lightning, and quantum tunnelling

I know that electricians speak of an open circuit as having "infinite resistance". Would it be accurate, though, to say that the existence of lightning proves that air has only finite resistance, and that quantum tunnelling implies the impossibility of truly infinite resistance even across a vacuum? NeonMerlin 05:52, 18 November 2011 (UTC)

An open circuit has a practically infinite resistance; the term is used because the multimeter is unable to detect it. Given enough voltage, there are no electrical insulators, however, merely less good conductors. Also, there's no need to invoke quantum tunnelling to explain the transmission of electricity across a vacuum. Classically, electric charge can be transmitted through a vacuum with no troubles. --Jayron32 06:11, 18 November 2011 (UTC)

While a vacuum does make a good insulator, it actually does not have resistance in an Ohm's law sense. Charges launched into a vacuum do not experience any resistance to their travel since there is nothing for them to collide with. Vacuum, it could be said, actually has zero resistance, not infinite resistance. However, vacuum will not usually conduct because it contains no charge carriers (it is a vacuum). To get it to conduct, charge carriers have to first be injected - see vacuum tube. SpinningSpark 12:31, 18 November 2011 (UTC)

Yes, but the force exerted by one charge on another charge works just fine in a vacuum. So you can "conduct" electricity across a vacuum. Actual electrons don't have to move across a region to count as electricity. Even in a wire, electrons don't "flow" down the wire like water in a pipe (despite the usefulness of the pipe analogy in other contexts). The better model of electricty in a conductor is the Newton's cradle: electrons crowded in a tight space and passing energy down the wire without themselves moving the length of the wire. In a basic sense, any movement of electric charge is electricity, and there's nothing inherent about a vacuum which stops this... Of course, there's the bit of problem that once you put some electrons inside a hard vacuum, it is no longer a hard vacuum... --Jayron32 14:46, 18 November 2011 (UTC)

I agree that conduction can take place in a vacuum, that is why I said that a vacuum has zero resistance. However, transmitting electricity across a vacuum without the use of electrons (or some other charge carrier) is not conduction, let alone ohmic conduction, it is launching an electromagnetic wave which is an entirely different phenomenon. The Newton's cradle model (or more accurately, the Drude model) is entirely unapplicable to conduction in a vacuum tube. The Newton's cradle model is poor anyway because most of the energy is not lost in at each collision of the balls whereas in a conductor electrons lose their forward momentum at each collision (hence the heating effect of an ohmic current). SpinningSpark 17:46, 18 November 2011 (UTC)

Our article on permittivity explains the concepts here, although it's a bit technical. Looie496 (talk) 16:19, 18 November 2011 (UTC)

Permittivity is a property of physical materials, not of the vacuum. The quantity vacuum permittivity is not the same thing, it is a dimensional constant dependent only on the system of units in use. SpinningSpark 17:59, 18 November 2011 (UTC)

Our articles on Cold cathode technology and our article on Vacuum tubes state that "cold cathode" tubes have some gas in them to allow conduction.Ionized gas molecules can certainly carry large currents. Cathode ray tubes and vacuum tubes certainly carry electron currents through a high vacuum from a heated cathode or filament. But a company called AFS says on their website that their high power tubes have cold cathodes and imply that they have vacuum rather than gas in them, and use a "strong electric field" to cause electrons to be emitted, allowing tens of thousands of amps. On page 7 they say "cold-cathode field-emission electron tube(s)" "just have to convince the electrons to propagate across a vacuum" as "plasma." How does this square with what Wikipedia says? Do the tubes really contain gas, or can "cold cathode" tubes conduct high currents of electron in a high vacuum? Edison (talk) 19:05, 18 November 2011 (UTC)

Vacuum has zero resistance, as long as you have free electrons in it to provide the current. The question is where are the electrons going to come from? The electrons can be provided by a cathode, but metals don't part from their electrons willingly. Some energy must be provided for that to happen. That energy can be provided by either heating up the cathode (hot-cathode) or by pumping the electrons out with a strong electric field (cold cathode). Dauto (talk) 19:53, 18 November 2011 (UTC)

Neutrino Circuit--real or a hoax?

http://www.youtube.com/watch?v=9uZ6elCRzNM This video. I googled and found nothing but copies of the same video and Wikipedia doesn't mention "neutrino circuit". Real or a hoax? Are you ready for IPv6? (talk) 10:26, 18 November 2011 (UTC)

There are about a zillion free energy hoaxes on the Internet. Wikipedia only mentions the few that have garnered significant media attention. (Blacklight Power, Stanley Meyer's water fuel cell, etc)

Just about any time anyone claims that the reason you haven't heard of something is because the "oil companies" are suppressing it, you may safely assume it's a hoax. The oil companies are very powerful, but there are a large number of equally powerful corporations that would love to have a free energy source.

(In fact, with enough energy, petroleum can be synthesized from waste! You can't tell me that ExxonMobile wouldn't like to get their hands on that before BP does!) APL (talk) 10:38, 18 November 2011 (UTC)

There's also the recent Energy Catalyzer although the merits of that article are still debated by some Nil Einne (talk) 14:43, 18 November 2011 (UTC)

I'm not sure what the gag is here, but it occurs to me that it'd be pretty easy to hide some batteries in the two thick "feet" on the base of the device. There's probably wires running through that otherwise unnecessary horizontal brace running along the center of the device. The whole device is held together with screws, so it can probably be opened to replace the batteries. APL (talk) 10:56, 18 November 2011 (UTC)

A stack of 3 volt button cells inside the rods would also get about the required voltage to make this work. I am not a physicist, but I would bet my house that there is no way this could possibly be done powered with solar neutrino flux. The device simply does not have a large enough cross-section to capture enough power even if there were a practical way of doing it. The article says the flux is 10¹⁴ (SI units) and solar neutrino says the energy of solar neutrinos is up to 18 MeV. The average energy is way less than this, but even giving the benefit of the higher figure and assuming 100% capture efficiency this only returns a power of 16 μW per square metre and the device has nowhere near that large a cross-section. Even with 1 m² that is barely enough to cause a crackle on your radio, let alone light a 25 W lamp. In any case 100% capture efficiency is entirely unrealistic for such a small device. The vast majority of neutrinos pass straight through the entire earth as if it wasn't there. Filling the entire distance from here to the sun with lead would only succeed in stopping half of them. In short, yes it is a hoax. SpinningSpark 12:17, 18 November 2011 (UTC)

One rod is made of 73 different elements, one rod is made of 74 different elements. That's a large chunk of the periodic table but okay.... Nil Einne (talk) 12:45, 18 November 2011 (UTC)

Does the sun really only produce that little energy in neutrinos? Thats less than 1 in 60,000,000 compared to photon energy. Surely the nuclear reactions involved disappate more than that fraction of energy in neutrinos. Can any one confirm that from the 4H→He +2 neutrinos reaction? I have no doubt that this machine does not work as promoted either. Graeme Bartlett (talk) 12:53, 18 November 2011 (UTC)

Before someone else points it out, I made an error in the power calculation above, I forgot to multiply by 18x10⁶. But there is still no way it is going to work. SpinningSpark 12:55, 18 November 2011 (UTC)

While we're here, the Blacklight articles says "that produces electricity for 1 cent per KW". This doesn't make much sense as it's a unit of power, not energy. Unless they make that mistake? Grandiose (me, talk, contribs) 13:29, 18 November 2011 (UTC)

Just because you piqued my curiosity, could you clarify: you're saying now that the Sun radiates about 1/3 the energy in neutrinos that it radiates by light? Can we nail down that ratio precisely - is it the result of some kind of equipartition theorem in the fusion reaction...? Wnt (talk) 14:55, 18 November 2011 (UTC)

Are you addressing that to me? I don't know any more than there is in the Wikipedia articles from where I got those figures. SpinningSpark 17:22, 18 November 2011 (UTC)

The Sun radiates only about 3% of its energy as neutrinos, see Proton-proton chain reaction. Icek (talk) 19:34, 18 November 2011 (UTC)

Neutrinos can also be produced by the CNO cycle and the Urca process, but those are not very important in the sun. Dauto (talk) 22:59, 18 November 2011 (UTC)

Ordinary little Christmas tree lights only use a couple of volts each and could easily be powered by batteries supplying a few volts to the rods. But the large light bulb is a puzzle. If it were running on 120 volts, it seems like the guy would get a shock when he touches both of the rods, which he appears to do several times. However, they make 12 volt 25 watt bulbs with the same shape and base as regular 120 volt bulbs. So if I were called on to build a device which would perform like the one in the video (not implying that this is how his device works), I would hollow out the large pieces of wood which make up the base, and are clearly not needed to support the claimed small weight of the device, and put in 8 C-size alkaline batteries, or D-size if they could fit, to equal 12 volts, then wire several of the little Christmas tree lights in series to use the 12 volts, or put several 12 volt Christmas lights in parallel, and buy a 12 volt, 25 watt A19 bulb for the big finale. D or C batteries could easily supply the 2.1 amps required by the bulb. Maybe even AA could do it for the short time required. The big light bulb could also be of the sort used in the "human powered light bulb trick," where a real looking bulb actually has LEDs or a small flashlight bulb and a battery inside, and is lit by shorting the two parts of the base with a piece of metal. See "Brain powered light bulb." The thermal inertia evident in the time it took the big bulb to go dark is consistent with an incandescent 12 volt bulb rather than a little flashlight or led bulb inside the globe. When he said "73 elements in one rod and 74 in the other," that might mean "73 units of some type" rather than 73 different elements of the periodic table. Here is a 1921 article using the term "battery elements" to refer to the lead plates in a storage battery. This use of "element" has a long history in electrical terminology. 1872: "On testing the battery of 80 elements..." The rods look a lot like the carbon rods once used in the big "ignition" dry cell batteries. Edison (talk) 16:59, 18 November 2011 (UTC)

The rods in that video look exactly like graphite rods in 6V lamp batteries. I've used them for electrolysis, and the batteries are pretty easy to take apart. --140.180.3.244 (talk) 18:50, 18 November 2011 (UTC)

The 6 inch tall "Number 6" ignition cells I remember put out 1.5 volts. They don't seem to make gigantic carbon zinc cells like that any more. Now they have a look-alike with 2 smaller "F size" alkaline cells inside, wired in parallel: [2]. Edison (talk) 04:50, 19 November 2011 (UTC)

Why would 73 units of some type and 74 units of the same type result in the charges differing? In any case, the specific comment was "73 different elements", I don't see why you would use different if you intended to imply they were 73 units of one type. (I'm not saying having one extra element would definitely make one positive and one negative but it makes slightly more sense.) Nil Einne (talk) 23:31, 18 November 2011 (UTC)

He did point out that the voltage stayed the same as he moved the light up and down the rod, possibly intended to show it was not a Voltaic pile with, say, 73 "elements" of copper, zinc and paper soaked in saline in one side and 74 such elements in the other side. I agree the phrasing is puzzling. I would expect only a small voltage difference between a stack of 73 and a neighboring stack of identical "elements," if each was the same sort of neutrino catching doo-dad. Did he ever imply the "elements" were stacked, or concentric cylinders, or a mixture, or some other configuration? Edison (talk) 04:50, 19 November 2011 (UTC)

In the video he said

Now it's compressed. The material in this, is made of; one rod is made 73 different elements, the other side is made of 74 elements. There's one additional element, and that's why one is negative and one is positive. One builds up the electrons. The neutrinos that strike the earth 24 hours a day and other things striking the earth, the combination of them causes electrons to build up in one of these rods and it depletes them in the other side.

I don't see any way this can be read as to mean anything other then there being 73 different elements in one side and 74 different elements in the other side. Even if he didn't mean chemical elements (and I would suggest if he didn't I would suggest element was a rather poor choice of terminology in the context), he clearly meant different stuff, not just 73 units of the same thing. Also he's clearly saying the additional element means a potential difference to arise between the two rods (because of neutrinos and whatever else). I don't know and didn't pay much attention to what he talked about later, listening to the intro was enough to convince me he was talking nonsense, which was my main point from the beginning.

BTW there's some suggestion the actual intented meaning was element 73 and element 74 [3] [4]. In the Youtube link it's mentioned the clip comes from a movie "Undeveloped Tech". It's easy to find that movie shows stuff invented by DL and his company BWT although I'm not sure which one, if any, he is in the specific clip. Per the earlier refs, DL appears to have a fairly poor reputation even among free energy people (also look for him at http://peswiki.com). According to [5] at one stage he couldn't even spell neutrino on his website (can't find the wording anymore although there's still this very low quality video [6] which uses that spelling and I think [7] is related to the DL guy somehow).

Mind you, as said it is unclear if DL has any real involvement, the main 'inventor/s' (perhaps the person demonstrating the device in the video?) and companies/people involved seem to be not directly connected to DL. In the earlier refs and [8] it's also suggested the element thing and possibly even neutrino was just a smoke screen by the inventor to cover how the device really worked and how simple it is. Funny enough for something so simple they appear to be having lots of problems making the device.

P.S. I censored the name but the links do name him directly which was fairly unavoidable. If people feel this is a problem per BLP, feel free to remove them.

Nil Einne (talk) 12:06, 19 November 2011 (UTC)

Perhaps the "73 elements" terminology comes from half-understood 19th century electrical books or articles, jumbled together to sound impressive. Interpreting the phrases in the video could be like trying to interpret David Copperfield's magical patter as descriptions of scientific phenomena. Edison (talk) 03:27, 20 November 2011 (UTC)

hydrogen bonding

Why phosphoric acid is a syrupy liquid? — Preceding unsigned comment added by Jyotiprakash hati (talk • contribs) 18:35, 18 November 2011 (UTC)

The title you chose for this section is the answer to your own question. 67.169.177.176 (talk) 22:45, 18 November 2011 (UTC)

exercise not improving fitness

For the last three weeks I've been running a route three times a week that is 4.6 miles (7.4 km). I've been very interested to see how my performance is improving over this period, especially as I have entered a December race. Unfortunately, my watch says I'm getting slower and my body tells me it's working harder. I'm generally curious about the effect of regular exercise on fitness and have just read the exercise article. Now I'm stressed because of this: "where most people will see a moderate increase in endurance from aerobic exercise, some individuals will as much as double their oxygen uptake". How do I know if I'm one of the unlucky few? Judging by the last three weeks of running, it seems I might be! 86.7.42.12 (talk) 18:45, 18 November 2011 (UTC)

Have you considered that you might just be tired?

Anyway, shot in the dark, let's see if this comes up blue: overtraining. --Trovatore (talk) 18:48, 18 November 2011 (UTC)

I get plenty of sleep and while I'll occasionally be more tired on some days than on others, what I've been noticing is a gradual but steady decline in my performance. The distance I run is split in half; 2.3 miles at the beginning of the day and the same again in the evening. So as far as exercise goes, it's nothing! Almost certainly not enough to consider it overtraining. I've also been making sure I get enough protein in my diet and enough water. 86.7.42.12 (talk) 18:58, 18 November 2011 (UTC)

Well, I can't tell you. But I am curious about your "unlucky few" remark. You do know that increasing your oxygen uptake is good, not bad, right? --Trovatore (talk) 19:41, 18 November 2011 (UTC)

Oh. Well, I figured it meant that you needed twice as much oxygen to do the same amount? Embarrassed that I've completely misunderstood that then... 86.7.42.12 (talk) 19:50, 18 November 2011 (UTC)

Well, needing more oxygen when resting could be bad, although if you have a larger body now due to more muscle mass, even that might be OK. StuRat (talk) 19:54, 18 November 2011 (UTC)

So you understand that high oxygen uptake is different from breathing hard? Breathing hard — hyperventilation — may mean a lot of oxygen is going in, but then just going straight out again. Oxygen uptake is how much actually goes into your blood, and the only reason it goes into your blood is because you're using it, for aerobic metabolism. --Trovatore (talk) 20:18, 18 November 2011 (UTC)

Right, and a high oxygen intake when resting probably means a high basal metabolic rate. That could be good, in a way, in that you would tend to burn more calories and avoid obesity, but, ultimately, having a lower basal metabolic rate is probably better, as long as you can reduced your calorie intake accordingly, as this will slow the oxidation in the cells (yes, antioxidants also help, but not 100%). StuRat (talk) 20:47, 18 November 2011 (UTC)

I understood the passage to mean higher oxygen uptake when exercising. --Trovatore (talk) 21:24, 18 November 2011 (UTC)

If you want to be diagnosed to see if you have some medical condition, this is not the place. If you want an idea of how people react to suddenly starting a strong exercise regimen, look at boot camp. Marines show up and immediately start a hard exercise regimen. It usually takes about a month before they start getting used to it. After three months, they are capable of performing the regimen without a real problem. -- kainaw™ 19:46, 18 November 2011 (UTC)

Something else to watch is your diet. You are presumably hungrier now that you are exercising, and how you satisfy that hunger could make a difference. If you reward yourself after each run with a dozen donuts, then you might do more harm than the exercise did good. StuRat (talk) 19:57, 18 November 2011 (UTC)

All I can suggest is to take a weeks brake. Then run another 4.6 miles. If you're back to a shorter time, then I have a clue, but I can't break the Wikipedia policy on medical advice to tell you here. Different people take different times to get rid of lactic acid build up, sometimes 48 hours or more. You will just have to work this out for yourself. --Aspro (talk) 20:25, 18 November 2011 (UTC)

Or perhaps a week's break. A weak brake belongs on the car of your least-favorite politician. :-) StuRat (talk) 04:39, 19 November 2011 (UTC)

You've not said how long the race you're training for is; from that regime I'll guess it's a 10k. Some observations:

• To be on the safe side, regardless of your age, get a check up from your doctor. There are any number of things that affect your performance at long-duration aerobic exercise. Better to discover if you have any of them now than during the race. I ran a race in September and passed several people (who looked younger and fitter than me) being helped by marshals, including one who was getting CPR.
• I wouldn't expect to notice any appreciable gain in 3 weeks. Unless you're in your late teens or early 20s, like Kainaw's marines, I'd expect you'd see only very modest improvement in 3 months. And those guys suffer.
• Ideally you'd train with some more experienced runners; see if there is a local running club. If you really can't do that, at least get a decent running book (Paula Radcliffe's how to run is pretty accessible).
• This morning+evening thing you're doing is very strange. It takes several miles to get warmed up and ticking over nicely; you're stopping just as the unpleasantness is beginning to pass.
• Every programme I've seen has you running significantly longer on one day (usually Sunday) than the others.
• If you've not run regularly before, 4.6 miles is quite a lot.
• Crazy people, who've heard that "exercise needs willpower" show up underprepared for a race and think they can will their way to the end. Maybe they can, but maybe they'll die. The willpower part comes in for all those long runs in the dark and the snow months before the race.

-- Finlay McWalterჷTalk 20:58, 18 November 2011 (UTC)

Thank you for such comprehensive advice! The race is a 5k and held once a month, so I intend to run it regularly and am focusing on improving my time. When I feel up to it I'll start working on 10k.

• I'm 27 and have had check-ups a few times in the past ten years. No problems and I have perfectly average blood pressure (assuming that blood pressure is an important thing to consider for exercise).
• I'm okay with suffering! I wasn't necessarily thinking I'd be seeing a lot of improvement in 3 weeks, but definitely not expecting for it to get harder.
• The book is a great idea, and I've been meaning to go along to a local club for a while. I'll make a point of doing that now.
• The morning then evening thing is because I'm running to and from work. I'm also running with a small backpack, so I'm carrying some extra weight in addition to my 9 stone (though it really isn't much).
• I really should be running the full distance for the race for proper practice, yes. I'll do that.
• I used to run fairly regularly (as in about 6 months ago) and my time for a 5k race in July was 27 minutes, so I'm not a complete beginner.
• Definitely not thinking of going into it without proper practice! But thank you for the warning.

Thanks everyone again for the help and advice. I really want this running thing to work! Sorry about the confusion with oxygen uptake, the sentence felt like it should read 'negatively' and I didn't think about it enough! 86.7.42.12 (talk) 08:58, 19 November 2011 (UTC)

Let me mention food again as an issue. I go onto a cross-trainer twice a week. This has the advantage of measuring energy expended and heart rate (and has a big-screen TV where I can get my weekly fix of either Star Trek or The Borgias). It makes a huge difference if I go up without a snack (typically 6 hours after lunch), or if I have a banana or a small sandwich about an hour before training). --Stephan Schulz (talk) 09:11, 19 November 2011 (UTC)

It seems to me that you are not training intensely enough. You should exercise for 20 to 30 minutes, at a heart rate around roughly 150 bpm (the optimal value will vary from person to person, for someone below 30 it will more likely be a bit higher than 150 bpm than lower). You may find out that you can only run fast for say, 12 minutes. In that case then you should execise for 12 minutes at that high intensity for a while. You should do this 4 to 5 times per week. This sort of exercise will lead to significant improvements in fitness. You should then gradually increase the time you exercise to 30 minutes or even longer.

Also you should exercise for running the distance you want to run, but you do that at a slower pace, simply to get used to running that distance, not per se to improve fitness. Now, because you aim to run only 5 km, you may not need to do this, you'll likely be able to get to that 5 km simply by increasing the amount of time you can run fast. To run 5 km, you only need to run 23 minutes at a speed of just 13 km per hour, which is a reasonable target for someone aged 50, let alone for someone aged 27.

With proper training almost everyone around 30 years of age should eventually be able to run the 5 km in less than 18 minutes, perhaps close to 16 minutes, which is still way off the World Record of 12 minutes and 37 seconds. Count Iblis (talk) 21:02, 20 November 2011 (UTC)

Solar sail max speed

If we assume a solar sail based object in vacuum with the following criteria:

• Constant source of radiation pressure along the traveling distance,
• No other effects of forces such as gravity.

Then what would be the maximum theoretical speed (with respect to a stationery observer where the solar sail started)? I couldn't figure if acceleration will tend to zero with time or stay constant while the relativistic mass increases.--109.74.32.237 (talk) 18:59, 18 November 2011 (UTC)

The maximum speed is (unsurprisingly) the speed of light (Assuming the radiation is constant). The acceleration (as seen by the "stationary" observer) tend to zero as the relativistic mass increases. Dauto (talk) 19:35, 18 November 2011 (UTC)

But, of course, you'll never get near that because:

1) You will move away from the star providing the radiation pressure.

2) There is no pure vacuum in space, and at high enough speeds the drag from space dust would be enough to counter the radiation pressure. And the solar sail will also be destroyed by that dust at some point. Even if stationary, micrometeors would still eventually destroy the sail. StuRat (talk) 20:02, 18 November 2011 (UTC)

1) The OP didn't say anything about stars. He mentioned a constant pressure

2) He also mentioned he wanted us to ignore all other effects

-- Dauto (talk) 20:47, 18 November 2011 (UTC)

Forces analysis

In the solar sail article (Mathematical survey section) it was written: "The light force can be separated into the normal force (away from the light source) and the tangential force as a function of the angle A of the sail face to the light. The Normal Force per area = 8/9 $cos^{2}A$ + 1/9 $cosA$. The Tangential Force per area = 4/9 $sin2A$."

May I know how this was calculated or at least a reference for that? I've tried to used conventional calculations for Lightness number from the Wikipedia article highlight and found it to be around <math>1.46*10^{-3} * \frac{mass}{area}</math> $1.46*10^{-3}*{\frac {area}{mass}}$ (The article I am writing is in an Arabic questions and answers site here). --89.189.69.209 (talk) 14:42, 20 November 2011 (UTC)

There is something missing in this equation. The units don't match. Dauto (talk) 15:57, 20 November 2011 (UTC)

If you were referring to the last equation, it is derived from the light force acceleration to gravity ratio and the constant $1.46*10^{-3}$ should have units of $kg/m^{2}$. There may be some mistakes (I've corrected there above) in the equation I derived but what concerns me now is the Wikipedia previous phrase analyzing force to its normal and tangential components.--Almuhammedi (talk) 19:30, 21 November 2011 (UTC)

Specific Gravity of various substances

My son needs a reference point for the specific gravity of Styrofoam, Pine Wood and Pine Bark. Its for a 7th grade science project, and he and I have both surfed, but can't find a reference that looks like they really know what they're talking about. He's doing an experiment to show the bouyancy of objects in water. The teacher picked the objects. If you can just point me in the right direction I would appreciate it immensely. Tanstaafl37 (talk) 20:45, 18 November 2011 (UTC)

Have you considered measuring it, instead of taking it from table? It's not too hard. Dauto (talk) 20:48, 18 November 2011 (UTC)

The experiment should provide the answers (which he is to perform) ... or am I missing something?--Aspro (talk) 20:53, 18 November 2011 (UTC)

Aw-shucks, I think I see a problem with our article on Specific gravity, is far too complicated for this grade. Just find out how the teacher wanted the experiment to be done, and just do it.--Aspro (talk) 21:06, 18 November 2011 (UTC)

Yes, it's not written for 7th grade, is it? There are numerous variations on a simple experiment to measure specific gravity of irregular buoyant objects. They all use Archimedes' Principle (a shorter article more suited to your son's level of study). Is your son expected to design his own experiment, or has he been shown a standard method? Dbfirs 23:46, 18 November 2011 (UTC)

At the 7th grade level, "specific gravity" is essentially equivalent to "density." There are a few nuances - if you want to be technical - but if you just want to measure specific gravity, you do so in the same way you measure mass-density: you weigh the object; and you measure its volume (usually by measuring the displaced volume of water when you submerge the object). If you want to get into the finer nuances, you can discuss the difference between mass and weight; you can discuss the different effects that temperature and pressure have on volume of water and volume of the test object; and you can discuss sensitivity analysis and experimental error. You can also discuss why we measure specific gravity; and you can discuss the benefits of normalization of the measurement to a common substance (e.g., water). Nimur (talk) 01:04, 19 November 2011 (UTC)

The following is my suggestion for the simplest way to measure specific gravity: equipment needed -- kitchen scale with a zero function, dish of water, spike (or finger). method: 1) weigh the object. 2) place a dish of water on the scale and zero the scale. 3) push the object into the water until it is just submerged (a spike instead of a finger will give better accuracy). 4) read the weight. 5) divide the first weight reading by the second. I leave it to your son to explain why this gives the specific gravity of the object. Dbfirs 12:59, 20 November 2011 (UTC)

Essentially, specific gravity is the density of an object compared to the density of water (potentially calculatable by weight in water vs. weight in air, IIRC). The article says the experimenter needs to maintain a standard "control" for the experiment in terms of temperature and pressure. That should not be too difficult, but increases in difficulty when trying to do it with accuracy: do it in the same day.

I remember creating a method of making the measurements without needing to use weight scales of any kind, needing no measuring equipment except a ruler. This is quite inaccurate for most objects (I determined the SG of a metal nail to be 8) but for rectangular masses it may be no problem. All that is needed is to compare the water displacement due to volume in the water (required to submerge the entire object in water without adding your hand, or simply measure the dimensions of the object to find the volume), versus the displacement due to mass of the object. To find the mass displacement, put the entire object in a non-permeable container such as a plastic one, and measure the volume of the water displaced by the container holding the object, averaging it out from the wave motion in the larger container that holds water. Divide the mass displacement by the volume displacement, and this is your SG; however I have not experimented using very large objects, nor those with SG>1.0. The error created by the container itself is also uncertain. Can somebody expand on my method? ~AH1 ^(discuss!) 21:52, 20 November 2011 (UTC)

MO theory and the shapes of molecules

can one determine the shape of molecules using only MO theory?(i.e. without using hybridization model?)--Irrational number (talk) 20:55, 18 November 2011 (UTC)

Yes. 67.169.177.176 (talk) 22:48, 18 November 2011 (UTC)

um.... A bit more explanation?like how?(i'm the OP)--81.31.191.221 (talk) 05:27, 19 November 2011 (UTC)

Actually, for covalent molecules you don't even really need either the hybridization model or the details of the MO theory. All you gotta do is figure out the Lewis structure, and that will give you the shape of the molecule. Of course, when you start talking about transition metal coordination complexes (like for instance nickel carbonyl), then you have to figure out the d-orbital splitting to determine what basic shape the complex will assume (e.g. octahedral, square planar, tetrahedral, etc.) and whether there will be any Jahn-Teller distortion. However, often you can determine the basic shape just by seeing how many ligands are bound to the central atom, e.g. if there are six ligands then you can bet your life that the complex will be octahedral. For complexes with four ligands, it's more complicated because they can be either tetrahedral or square planar, which you can often figure out from the number of d-electrons on the central atom. Likewise, for complexes with five ligands there are two different geometries (square pyramidal and trigonal bipyramidal), but it doesn't really matter because they'll be in equilibrium anyway. In any case, once you're done with this, you'll have to determine the d-orbital splitting in order to see if there's distortion, and that's where the MO theory comes in -- you have to figure out the symmetries on all the orbitals, then mix and match the orbitals with the right symmetry, then place the electrons according to the aufbau principle, and that will tell you if there's any Jahn-Teller distortion. 67.169.177.176 (talk) 07:44, 19 November 2011 (UTC)

to put it another way, is it possible to verify the shapes (derived by other methods) using MOT?--Irrational number (talk) 19:13, 19 November 2011 (UTC)

Yes, it's very much possible to verify the shape of a molecule by matching the symmetries of the electron orbitals. 67.169.177.176 (talk) 21:08, 19 November 2011 (UTC)

Yes, there are a number of methods. One of the more common ways to do it is, I believe, the Hartree–Fock method. Needless to say, you need a computer to do any calculations on anything but the very simplest of molecules. Basically, you have a way to calculate the (approximate) energy for any given configuration of atoms in space, and you minimize that energy. Buddy431 (talk) 18:33, 20 November 2011 (UTC)

Yikes, memories of porting Hartree-Fock analysis (in FORTRAN) from a mainframe to a PDP-11 back in college, must be nearly 35 years ago, now. PЄTЄRS J V ►TALK 18:56, 20 November 2011 (UTC)

Note that this whole discussion is about determining what the molecule is predicted to be based on various theories. The molecule "just is" and has its shape as a fact of nature. All we can do is rationalize why using theories verify the theories (studying them to find which ones agree with fact). And then use the theories to predict what other molecules might probably look like in the domains where the theories are known to be consistent with nature, rather than using the theory to prove the fact of the structure. DMacks (talk) 19:35, 20 November 2011 (UTC)

Yes, that's what I was gonna say -- all these methods could be used to predict the shape of the molecule, but you still have to verify it experimentally. 67.169.177.176 (talk) 21:34, 20 November 2011 (UTC)

Extension cord AMP ratings

I need to buy 3 extension cords. The store seems to have them in ratings of 10A, 13A, 15A, 20A, and 30A. So, what's the minimum required for:

1) A 1500 watt, 120 volt space heater.

2) A 500 watt, 120 volt space heater.

3) An average-sized 120 volt refrigerator with top freezer compartment. StuRat (talk) 21:01, 18 November 2011 (UTC)

Copper is going up in price. Seize this opportunity to grab some extensions that you can use in the future for higher wattage appliances. Spend now save latter! --Aspro (talk) 21:15, 18 November 2011 (UTC)

Fire marshals will tell you never to use an extension cord with any of those appliances. That said, for permanent circuits, 14-ga cable will carry 15A/1800W, 12-ga will carry 20A/2400W. While short cords can be de-rated, as can intermittent loads, if you're hooking up resistance heat loads or major appliances with motor starting requirements, it's best to go with a cord that matches the permanent wiring requirements. A refrigerator requires a 20A circuit, and the space heater at a full 1500W will start to heat its cord, so I'd go with 20A cord for that and keep each cord to the shortest length that will suffice. You should never coil or bunch excess cord - I know someone who who had to throw a smoking extension cord out the window after it was hooked to a space heater while coiled. The 500W heater can probably live with the 14-ga/15A cord. That's the lowest I would go for loads like that. Anything smaller would be for intermittent use or light-duty lighting. Acroterion (talk) 22:44, 18 November 2011 (UTC)

Thanks. I was thinking the 500 W heater would only need 1/3 the amp rating of the 1500 W. Why isn't that the case ? As far as avoiding coiling the cord, how should you take up the excess ? StuRat (talk) 22:58, 18 November 2011 (UTC)

The 500 W heater would be OK with the 10A extension, but it is always better to err on the safe side, as advised by Acroterion. I too have seen coiled extensions melted by a load within the rating because of the induction in the coil. Best advice is to uncoil the full length and avoid any repeated loops. Random looping will be fine as long as there is no bunching. Even better would be to find a route that allows the full length to be stretched out, but this is not strictly necessary as long as loops are large and not repeated in the same direction. Dbfirs 23:35, 18 November 2011 (UTC)

I doubt there is much heating due to inductance, compared to the resistive heating in the cord. Coiling it up decreases its ability to dissipate heat. Anyone care to calculate the inductance of an extension cord? Edison (talk) 04:31, 19 November 2011 (UTC)

How would "induction in the coil" be affected by having equal and opposite currents in the two closely spaced conductors of the extension cord, inherent in AC (or DC, for that matter) power supplied to a device? Edison (talk) 03:18, 20 November 2011 (UTC)

You could get by with a relatively small cord on the 500W heater (say, 16-ga - 18-ga is lamp cord and not at all satisfactory), but with long-term heavy loads it's best to be conservative. At small wire gauges there's really very little copper, and a little damage can severely impair current-carrying capacity. Also, voltage drop increases as wire gets smaller or longer, which is a reason to keep cords short: the drop in voltage is the result of resistance, which produces heat. Vacuum cleaner cords tend to have very small wire gauges and heavy loads, and they can get quite hot, but vacuums are rarely on for more than a few minutes at a time. Using a cord only as long as it has to be lets you avoid coils, too. Acroterion (talk) 03:04, 19 November 2011 (UTC)

How about if you coil half the excess in one direction, then the other half in the opposite direction, attached to the first coil ? And as for "being on the safe side", if I need 15A to be safe with 500W, why don't I need 45A to be safe with 1500W ? StuRat (talk) 00:04, 19 November 2011 (UTC)

Two half-coils in opposite directions would be much marginally better than a single coil because you would cancel out most of the inductance, but I would feel safer with looser random looping. You are correct that watts are proportional to amps, in fact 500 watts is less than 4.2 amps so a 5 amp extension lead (available in the UK) would technically be adequate. Thin cable is easily damaged, hence the advice not to run it near the limit. 1500 watts is only 12.5 amps at 120 volts, so in fact the 15 amp extension would serve the purpose (but I would prefer to use 20 A to give a safety margin). If the space heater has a fan, this will draw extra current, especially as it starts up. Dbfirs 00:36, 19 November 2011 (UTC)

Nope, no fan. A pile of random coils would present too much of a trip hazard, so I'll try reversing the direction and monitoring the temp. StuRat (talk) 01:55, 19 November 2011 (UTC)

You could get by with a relatively small cord on the 500W heater (say, 16-ga - 18-ga is lamp cord and not at all satisfactory), but with long-term heavy loads it's best to be conservative. At small wire gauges there's really very little copper, and a little damage can severely impair current-carrying capacity. Also, voltage drop increases as wire gets smaller or longer, which is a reason to keep cords short: the drop in voltage is the result of resistance, which produces heat. Vacuum cleaner cords tend to have very small wire gauges and heavy loads, and they can get quite hot, but vacuums are rarely on for more than a few minutes at a time. Using a cord only as long as it has to be lets you avoid coils, too. If it's a loose coil you're probably OK. Acroterion (talk) 03:04, 19 November 2011 (UTC)

Why aren't extension cords on reel [9] a problem for inductance ? StuRat (talk) 01:59, 19 November 2011 (UTC)

Why do you think they aren't? Any decent extension cord on a reel for consumers always says to fully extend/unwind it before use (or at least for high loads), the same as do vacuum cleaners and such. (Our article also notes the requirement.) Nil Einne (talk) 03:03, 19 November 2011 (UTC)

Most cords on reels are used intermittently, so heating and inductance don't present such a problem. Acroterion (talk) 03:04, 19 November 2011 (UTC)

I beg to differ. As an illustrative anecdote, some (OK, about 30) years ago one of my bookshop colleagues started to vacuum our shop's carpet at the end of the day, as was routine. However, she neglected to first unwind the extension cord reel as was also usual, and after only a minute (very roughly) the reel started smoking, and on inspection significant amounts of the cord's plastic insulation and the plastic body of the reel were found to have melted. {The poster formerly known as 87.81.230.195} 90.197.66.55 (talk) 13:14, 19 November 2011 (UTC)

Much depends on the machine and the level of economy the manufacturer applied to the cord; I have two vacuums: one cord gets hot, the other doesn't. Per the note below, I think in most cases the problem is heat dissipation rather than inductance, as it's my understanding that the hot and neutral currents cancel inductance in a coiled AC cord, but it can become a significant issue where the hot alone is a coil, or where the hot and neutral are separately routed, as in knob and tube wiring. Acroterion (talk) 14:58, 19 November 2011 (UTC)

Does anyone here have a reference (or even a strong physics argument) suggesting that a coiled extension cord heats excessively due to inductance, instead of due to the concentration of heat source and lack of dissipation, as stated in our article? -- 203.82.66.198 (talk) 13:49, 19 November 2011 (UTC)

Acroterion is correct. The two wires inside of the cord carry opposing currents so they won't cause any induced currents in a neighboring coil. The overheating is such situations is really caused by bunching up too many warm wires together which prevents efficient cooling. Dauto (talk) 17:37, 19 November 2011 (UTC)

(edit conflict)::I wasn't thinking very clearly when I implied that inductance was a significant effect. In fact, at any instant, the current is flowing both ways in the coil, and only a systematic difference in the layout of live and neutral would cause a significant inductive effect. The main heating effect must be from the resistance in the wire and lack of heat dissipation in the coil. My advice for very loose loops is therefore much better than the suggestion of reversing the direction of half the coil. The safe answer, of course, is to use an extension of appropriate length and avoid any close aggregation of cable so that air cooling is optimised. I've modified my reply above. Dbfirs 17:44, 19 November 2011 (UTC)

Really, putting resistance heaters (in particular) on extension cords is a very bad idea. There is never a perfect connection between the heater plug and extension cord, leading to heat buildup at the connector. If you have that few outlets that you need extension cords (implying an older house with fewer outlets and likely all just 15 amp circuits), all the more reason, you'll also get heat build-up at the wall outlet connection. As for the fridge, not a hot (no pun intended) idea either, there's a reason that compressor-driven appliance (A/C, fridge, freezer,..) instructions state you should not use an extension cord. (And most electrical code requires a dedicated circuit for the refrigerator, that is—moreover—nothing else plugged in, anywhere, on that circuit.) In the meantime, if you are going to use an extension cord temporarily for any reason, it should introduce minimal resistance, so: copper, as short as possible, and as high an amperage rating as you have available. (Higher amp connectors will also dissipate heat better.) PЄTЄRS J V ►TALK 19:18, 20 November 2011 (UTC)

Extension cord heating

Follow-up Q: A longer cord means more energy is dissipated as heat. What about a thicker cord ? Does that mean more, less, or the same amount would dissipate as heat, assuming an identical length and load ? StuRat (talk) 15:06, 19 November 2011 (UTC)

Less. For DC, anyway, the power that a wire turns into heat is $P={\frac {I^{2}\rho \ell }{A}}$, where $I$ is the current through the wire, $\rho$ is the resistivity of the material (usually copper) that the wire is made out of, $\ell$ is the length of the wire, and $A$ is the wire's cross sectional area. So with everything else constant, a wire with a larger cross sectional area will generate less heat. The equation above is a combination of equations found at Electric power#Direct current and Electrical resistance#DC resistance. The power turned into heat is really somewhat more than in the equation above due to it being an AC current instead of DC, but I think it's close enough for this discussion. Red Act (talk) 16:48, 19 November 2011 (UTC)

Yes, much safer to use thicker conductors. Double the cross-section of the wire and you halve the total heat to be dissipated in the coil (approximately, ignoring the skin effect). AC calculations are exactly the same if you use RMS values (which nearly everyone does). Dbfirs 12:48, 20 November 2011 (UTC)

Flexible electrical insulation which is thermally conductive

Next follow-up Q: Is there any material which could be used for wire insulation which would conduct the heat away from the wires rather than holding it in ? Ceramics seems to be good electrical insulators and at least some conduct heat fairly well, but they aren't flexible enough. Perhaps some composite material containing ceramics ? StuRat (talk) 18:08, 19 November 2011 (UTC)

Small ceramic beads and manganese oxide copper sheath cables, are already used in some applications were silicon rubber or PTFE insulation is not heat resistant enough. Conducting heat away is the wrong approach. As I suggested at the start, get the highest amperage extension that you can afford – and educate everyone within the household, about the dangers of leaving them coiled up whilst in use (the fire brigade in the UK have a neat way of getting this across to new recruits – they show them photographs of the chard remains of those who who left their extensions coiled up).--Aspro (talk) 18:33, 19 November 2011 (UTC)

How about if you put the coils in a pail of water (and hope that the insulation is intact) ? :-) StuRat (talk) 18:46, 19 November 2011 (UTC)

Already invented. its called an electric immersion heater. Are your life and fire insurance polices up to date? :-)--Aspro (talk) 19:14, 19 November 2011 (UTC)

November 19

More force by pedaling

When pressing a bicycle pedal we press it with our weight on the pedal (x kg). What if we had some back support? Would we be able to put more pressure onto the pedal? Quest09 (talk) 00:49, 19 November 2011 (UTC)

Not with a regular bicycle. If you had something holding your shoulder's down, perhaps. StuRat (talk) 01:51, 19 November 2011 (UTC)

You have down on your shoulder? You silly goose. Clarityfiend (talk) 05:33, 19 November 2011 (UTC)

A recumbent bicycle has back support, and one was used to set the world speed record (though I infer this was due to reduced wind resistance). Clarityfiend (talk) 03:07, 19 November 2011 (UTC)

There's only a very brief discussion under Recumbent bicycle#Disadvantages (section Uphills), where it's observed that even on a normal bike you can still pull against the handlebars, and that recumbents are generally thought to be harder to pedal uphill, although this may be because they tend to weigh more. My thought is that although you could put more pressure on the pedal if you have something behind your back, it wouldn't be more efficient, because needing that much pressure would just mean you were in too high a gear for the task.  Card Zero  (talk) 03:14, 19 November 2011 (UTC)

Note that this is one reason why even semi-serious performance riders use clips and straps, or, nowadays, clipless pedals and matchings shoes. This allows you to exert force both on the up and on the downstroke, and thus in particular to exert more on the downstroke (since your other foot is keeping you down). --Stephan Schulz (talk) 09:25, 19 November 2011 (UTC)

Just from inference, the angle of the back to the seat, partly supported by hands on the handlebars, changes the pivot of the momentum of the foot on the pedal. ~AH1 ^(discuss!) 21:32, 20 November 2011 (UTC)

Acrobats demonstrate that a foot can put more pressure than a body weighs. Cuddlyable3 (talk) 19:28, 22 November 2011 (UTC)

Photon engine

Is it possible for photons to do work directly instead of converting it to heat or electric current? ScienceApe (talk) 03:29, 19 November 2011 (UTC)

Sure. Photons have momentum, and if they bounce off something then they do work. See, for example, solar sail and radiation pressure. TenOfAllTrades(talk) 03:35, 19 November 2011 (UTC)

The Radiometer article is in pretty rough shape, but I've added the illustration to this question. You can find these things in novelty shops. APL (talk) 03:47, 19 November 2011 (UTC)

A Crookes radiometer is not driven directly by radiation pressure, though this is a common misconception. The radiometer relies on greater absorption of photons by the dark-colored vanes and the conversion of those photons to heat (which in turn heats the adjacent air, generating thrust from the air's thermal expansion). As such, it's not a good response to the original poster's question. Indeed, if the Crookes radiometer were driven by radiation pressure, then it would turn in the opposite direction—there is twice the transfer of momentum when a photon is reflected as when it is absorbed, so the vanes would have a greater force on their white face than on their black face. TenOfAllTrades(talk) 04:05, 19 November 2011 (UTC)

Ah, you're right. I've removed the illustration. APL (talk) 04:11, 19 November 2011 (UTC)

Has anyone produced a radiometer in a vacuum bulb so that it does turn the other way? Sorry, the answer is in Nichols radiometer. Dbfirs 12:30, 20 November 2011 (UTC)

There have actually been proposals for a photon rocket (what, no article?), which would use the reaction force from an intense beam of photons to propel itself at speeds close to the speed of light. The only problem (aside from finding a suitably powerful energy source) is that light energy of such intensity can vaporize all known reflecting materials. So at present this is entirely in the realm of science fiction. 67.169.177.176 (talk) 07:49, 19 November 2011 (UTC)

I just now created a redirect, so that photon rocket is no longer a red link. Red Act (talk) 19:27, 19 November 2011 (UTC)

See IKAROS. Gandalf61 (talk) 10:29, 19 November 2011 (UTC)

Photons themselves have no mass but carry energy. Also examine for example the workings of a charge-coupled device. ~AH1 ^(discuss!) 21:28, 20 November 2011 (UTC)

cooling in vaccum

suppose any hot plate in vaccum space, in which gradient or ratio its cooling happens ?consider there is not any conductor except radiating.--Akbarmohammadzade (talk) 05:16, 19 November 2011 (UTC) I want to discuss about any star which has continues body such as t-tauri star comparing with spherical normal star such as sun.Too cooling regime of planets such as Earth with molten volcanic hot core .--Akbarmohammadzade (talk) 10:33, 19 November 2011 (UTC)

The hot item will radiate energy following the Stefan–Boltzmann law. In other words, the energy lost is proportional to the surface area and to the 4th power of absolute temperature. It will asymptotically approach the temperature of the environment - for a spherical cow that would be either 0 K, or the temperature of the cosmic microwave background, about 2.725 K. There may be confounding factors, like differences in albedo. For a body like the Earth you also need to modell how much energy is flowing from the hot core to the surface - energy is only lost at the surface, but vertical heat transport in the Earth is very slow. In the case of Earth, the geothermal contribution to the energy flux is only about 0.025% of the total. --Stephan Schulz (talk) 11:08, 19 November 2011 (UTC)

hydrogen bonding

why dissociation of soap or detergent in water produces lather or foam? — Preceding unsigned comment added by Jyotiprakash hati (talk • contribs) 09:26, 19 November 2011 (UTC)

The soap and detergent molecules each have a part that loves to be in water, and another part that is repelled by water. This causes them to stay at the surface of the water. You will also need mechanical agitation of the water to form the bubbles. This ends up lowering the surface tension, and allowing the surface to curve without much energy. See foam detergent surfactant and Foaming agent Graeme Bartlett (talk) 12:05, 19 November 2011 (UTC)

Pseudo science or genunie plughole at equator

I have been musing about it and wondered if I could have a definitive view on whether this equator plughole stuff is fake science in this video I suspect this is a stunt for tourists; I don't reckon a few hundred metres is enough for it to make a difference on plugholes and it is probably all in the shape of the tub? (Of course his comment near the end about weight is wrong, the 3% versus the poles might be right though). However I don't really have a feel for how sensitive a nonlinear instability might be to pick up the tiny difference from moving a few hundred metres and the plug hole going straight down is impressive. Thoughts? --BozMo talk 09:29, 19 November 2011 (UTC)

Actually it is rubbish at any latitude. It is practically impossible to open the plug without causing some arbitrary lateral movement within the water. The coriolis force of the earth is far too weak at the scale of a tub of water to override any number of other influences - even thermal convection would be far stronger - http://www.snopes.com/science/coriolis.asp . Roger (talk) 09:54, 19 November 2011 (UTC)

The statement "In reality, this motion would not be seen with a small amount of water – a huge mass of fluid is needed – so the demonstrator is using some showmanship to simulate the effect." at BozMo's link seems to be a giveaway ;-). --Stephan Schulz (talk) 11:10, 19 November 2011 (UTC)

I heared it's not the lateral movement you cause when you open the plug that's really significant, but the imperfect shape of any bathtub. – b_jonas 18:16, 19 November 2011 (UTC)

Unless it's something on the scale of the Equatorial Counter Current, any association between Earth's rotation and the rotation of toilets is not really that significant. ~AH1 ^(discuss!) 21:10, 20 November 2011 (UTC)

There's something mystical about "plugholes" that is far beyond my comprehension. I still remember using a darkroom, almost twenty years ago, which had a huge circular basin with the drain at the middle. The water would stagnate and refuse to drain the last inch or so, so that if left to itself the chemicals would crystallize out in the basin. But if a tube was placed above the drain, not quite touching it, I could turn the tap full on, and all the water would go down the drain without any obstruction. I must have spent a full hour trying to understand that sink... I still have absolutely no idea at all! Wnt (talk) 00:47, 21 November 2011 (UTC)

The only way for all the molecules of the stagnant water to go down the conical basin is for some molecules to go up. It seems some asserted their democratic right not to do so. Cuddlyable3 (talk) 19:13, 22 November 2011 (UTC)

Superluminal neutrinos

I would like to know more about the newly found fact that neutrinos travel faster than light.. — Preceding unsigned comment added by Sreevidyaphysics (talk • contribs) 11:13, 19 November 2011 (UTC)

I wouldn't call it a "fact" quite yet. Our article on the topic is OPERA neutrino anomaly; you could start there and then follow the links in the references and the "External links" section to learn more. Deor (talk) 11:23, 19 November 2011 (UTC)

It's not a fact. It's just an anomaly - that is an unexplained and likely incorrect observation. Out of the many possible explanations for that anomaly, superluminal neutrinos is one of the least likely. Dauto (talk) 14:35, 19 November 2011 (UTC)

What are the other explanations physicists are throwing around? Are any of them taking hold? Aaadddaaammm (talk) 15:46, 19 November 2011 (UTC)

Well, the most popular explanation is simple experimental error. They're ruled out one possible cause of error with the recent re-runs (by using shorter pulses), but there are plenty more possibilities to be considered. Until another team using different equipment have replicated the results, scientists will continue to assume it's an error. --Tango (talk) 16:17, 19 November 2011 (UTC)

sametime , time gose backwared , thanks wate nosfim — Preceding unsigned comment added by 212.199.175.104 (talk) 06:35, 20 November 2011 (UTC)

One claim mentioned a week or two ago in the weekly New Scientist magazine, which is of course following these events, was that the team had neglected to correct for the relativistic effects of the movements of the GPS satellites used to calculate the exact distance between the neutrino emitter and detector. However, that argument was no longer mentioned in the latest article in Saturday 19th's issue concerning the re-run. {The poster formerly known as 87.81.230.195} 90.193.78.12 (talk) 18:59, 20 November 2011 (UTC)

It looks like that explanation was based on a mistake - the guy who made it, Ronald van Elburg, seems to have applied the Lorentz transformation incorrectly, and by chance that incorrect calculation produced a number that roughly cancelled out the anomaly. Smurrayinchester 12:31, 23 November 2011 (UTC)

Recent observations continue to suggest the validity of experiments, but issues are being raised into whether the margin of error was greater than the anomaly of the result. See for exaple this article in Discover Magazine's website. From tachyon#Speed:

In 1985 it was proposed by Chodos et al. that neutrinos can have a tachyonic nature

Chodos, Hauser and Kostelecký (1985): The neutrino as a tachyon {Abstract} ~AH1 ^(discuss!) 21:07, 20 November 2011 (UTC)

inorganic chemistry

why concentrated sulphuric acid appears like an oil? — Preceding unsigned comment added by Jyotiprakash hati (talk • contribs) 15:01, 19 November 2011 (UTC)

You might have a look at Sulfuric_acid#Physical_properties & Viscosity#Viscosity_of_various_materials. It's worth pointing out that this has nothing to do with Inorganic Chemistry.(+)H₃N-Protein\Chemist-CO₂(-) 19:17, 19 November 2011 (UTC)

To clarify, Sulfuric Acid of course is of course an inorganic acid, but this seems like a solution chemistry question (ie more in the realm of pchem or analytical chem) and thus is not really an inorganic chemistry question. Apologies for any confusion I may have caused with my initial reply.(+)H₃N-Protein\Chemist-CO₂(-) 19:24, 19 November 2011 (UTC)

inorganic chemistry (isomeric ethers)

why isomeric ethers have low boiling point than alcohols? — Preceding unsigned comment added by Jyotiprakash hati (talk • contribs) 16:32, 19 November 2011 (UTC)

Excuse me if I'm mistaken but it seems like you've asking a series of questions taken from your homework in which case the best place to find the answers would be your text book and/or class notes. Dauto (talk) 16:50, 19 November 2011 (UTC)

I added to the title so we won't have two Q's with the same title. StuRat (talk) 19:38, 19 November 2011 (UTC)

Take a read of Ether#Physical properties. Graeme Bartlett (talk) 22:50, 21 November 2011 (UTC)

inorganic chemistry (why water is a versatile solvent)

why water is a versatile solvent?Jyotiprakash hati (talk) 17:10, 19 November 2011 (UTC)

Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our policy here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. 220 of ^Borg 18:38, 19 November 2011 (UTC)

I added to the title so it won't be identical to your earlier post. StuRat (talk) 19:40, 19 November 2011 (UTC)

I'll give you a clue: All the questions you've asked so far are variations on a single theme. That's all the help I'll give you for now -- you figure out the rest on your own. 67.169.177.176 (talk) 21:14, 19 November 2011 (UTC)

Try chemical polarity, if it helps. ~AH1 ^(discuss!) 20:59, 20 November 2011 (UTC)

Zion Nat'l Park stone tool?

I'm curious if I found a stone tool at Zion National Park. A photograph of the top and two sides can be seen here: [10]. The stone was the exact same color as the rock formations I found it on, which were near one of the entrances to the park. In the top picture, you can see how smooth the "handle" is (sorry for the out of focus-ness) and the tip of the tool looks like it was sharpened into a blade. I really couldn't believe this wasn't man-made. Any ideas? The article does mention "flaked stone knives", though I don't know what that is. Thank you!Reflectionsinglass (talk) 20:49, 19 November 2011 (UTC)

A flaked stone knife is a knife made by chipping off flakes of stone until you get a sharp tool. But this item looks more like it could be a scraper, which might be used to scrape flesh off of skins, so they don't rot quite so quickly (the best they could do before tanning). However, it could also be a natural rock. StuRat (talk) 21:35, 19 November 2011 (UTC)

IMO, natural. Fracture looks very fresh with no sign of usage wear. Compare with actual neolithic tools in our article on Stone tool.-- Obsidi♠n Soul 22:22, 19 November 2011 (UTC)

Hmmm, wonderful, thanks for the answers! The fact that it was just lying there out in the open may mean something too, tho I don't know what.Reflectionsinglass (talk) 00:15, 20 November 2011 (UTC)

I wouldn't dismiss it out-of-hand as not authentic. Stone tools and arrowheads are shockingly common in some areas. I am not familiar with Zion in particular, but my wife's grandfather was something of an amateur archeologist; he would comb through construction sites near where he lived in Wisconsin, and had collected several thousand arrowheads and other tools. So, while not every chipped rock is a man-made tool, it still could be. --Jayron32 03:51, 20 November 2011 (UTC)

I suppose then that I would have to find more, maybe. Is there an ethics thing about picking up/touching/removing stone tools from places? I didn't go into it, but I do have a twinge of guilt because I thought the scraper was cool (and man-made).`Reflectionsinglass (talk) 18:27, 20 November 2011 (UTC)

Removing archeological items from a national park is certainly illegal. Taking even things like rocks or flowers is typically not allowed. The rock that you have found looks entirely natural to me. — Preceding unsigned comment added by 148.177.1.210 (talk) 21:42, 21 November 2011 (UTC)

Ok, I wondered. I'll in good faith return it where I found it. It's been the source of fun discussions, though. Thanks all.Reflectionsinglass (talk) 21:03, 22 November 2011 (UTC)

Facial hair growth hormone?

i know that the Head-hair hormone is "DHT". what about facial hair hormone?, have we discovered it yet?.

thanks. — Preceding unsigned comment added by 109.67.12.102 (talk) 21:11, 19 November 2011 (UTC)

DHT is not a "head-hair hormone". DHT is dihydrotestosterone. DHTs role in baldness is complex; it appears that the hormone is responsible for development of secondary sex characteristics, such as facial hair growth. Some males have a genetic predisposition towards baldness, whereby DHT apparently deactivates the hair folicle in some way; but this is not a primary role of DHT, it is a complex hormone that does lots of things, many of which are unrelated to baldness. Also, the role of DHT in hair loss is not entirely accepted as described, at least according to the Wikipedia article Androgenic alopecia. If you read that article, so-called "male pattern baldness" is not simply due to DHT, but associated with a whole lot of hormonal effects. --Jayron32 22:30, 19 November 2011 (UTC)

and what about facial hair growth in males?. what could a man who has a sparse growth there do?. thanks. 79.183.13.71 (talk) 08:35, 20 November 2011 (UTC)

Well, some form of testosterone would be used to increase facial fair growth, as it is in those who have a female-to-male sex change. However, hormone treatments have serious side effects, so should certainly not be used just to get a thicker beard. Some type of cosmetics, something like mascara, might make more sense, to both thicken and darken the hairs they do have. Or just hair dye could be used, if the beard is too lightly colored. Just for Men is one such product. StuRat (talk) 17:14, 20 November 2011 (UTC)

The Just for Men range also includes dyes specifically for beards, though fewer outlets stock them than the hair dyes. I myself use one of the hair dye range to even up my rather piebald moustache and beard, as one can contrive several applications from the same pack, but I'm consciously contravening the manufacturer's reccommendations, so don't take that as advice ¦;-{))>. {The poster formerly known as 87.81.230.195} 90.193.78.12 (talk) 19:13, 20 November 2011 (UTC)

Genetics, androgen hormone availability and other factors determine facial hair growth. ~AH1 ^(discuss!) 20:55, 20 November 2011 (UTC)

what are this other factors?. do you guys know any bio-chemist who researched on this issue?. thanks.

Cancer

Hi, I would like to know: 1)What is the deadliest cancer?

2)Why do cells of pre-cancer get some properties that they didn't have.

Exx8 (talk) 23:18, 19 November 2011 (UTC)

See also: Cancer. →Στc. 00:00, 20 November 2011 (UTC)

Define "deadliest". Lung cancer kills the most people,[11] but pancreatic cancer is generally considered to be the deadliest in terms of prognosis at time of diagnosis (see http://www.helium.com/items/1993804-deadliest-types-of-cancer-with-the-worst-prognosis , which I can't link to normally due to a spam filter.) Glioblastoma multiforme is up there, too. Red Act (talk) 00:04, 20 November 2011 (UTC)

There are many potential definitions, for example: rapidity of onset, severity of illness, shortness of time elapsed between diagnosis (or metastasis, or first symptoms) and death of the patient, prevalence, earliest childhood cancers, etc. ~AH1 ^(discuss!) 20:38, 20 November 2011 (UTC)

For your second question, I'm no expert, but see articles glycolysis, tumor progression and metastasis. ~AH1 ^(discuss!) 20:41, 20 November 2011 (UTC)

Better yet, malignant transformation and carcinogenesis. TenOfAllTrades(talk) 23:38, 20 November 2011 (UTC)

November 20

Morning erections & psychogenic ED

In the Wikipedia article, "Nocturnal Penile Tumescence" it says:

"Nocturnal penile tumescence (informally known as "morning wood" or "morning glory") is the spontaneous occurrence of an erection of the penis during sleep. All men without physiological erectile dysfunction experience this phenomenon, usually three to five times during the night.[1] It typically happens during REM sleep."

But this, from the Cornell Urology Department, would seem to contradict that:

"One of the great myths in sexual medicine is that the presence of a rigid early morning erection indicates psychogenic ED. This is a false concept, as many men with significant arteriogenic ED wake up with good erectile rigidity. The presence of good early morning erections is suggestive only of adequate venocclusive function. (full article: http://www.cornellurology.com/sexualmedicine/ed/evaluation.shtml)

Is this a controversial issue in medicine? — Preceding unsigned comment added by 204.9.109.10 (talk • contribs) 00:17, 20 November 2011 (UTC)

I don't see any contradiction between the two texts. Dauto (talk) 00:26, 20 November 2011 (UTC)

Not with the section the OP quoted, but our article goes on to state:

The existence and predictability of nocturnal tumescence is used by sexual health practitioners to ascertain whether a given case of erectile dysfunction (E.D.) is psychological or physiological in origin. A patient presenting with E.D. is fitted with an elastic device to wear around his penis during sleep; the device detects changes in girth and relays the information to a computer for later analysis. If nocturnal tumescence is detected, then the E.D. is presumed to be due to a psychosomatic illness such as sexual anxiety; if not, then it is presumed to be due to a physiological cause.

which does sound contradictory. -- 203.82.66.204 (talk) 01:17, 20 November 2011 (UTC)

Male testosterone is highest in the morning. ~AH1 ^(discuss!) 20:36, 20 November 2011 (UTC)

Strictly, maybe not, but it may be misleading. I doBold text think it would be a useful counterpoint to include that someItalic text men withItalic text physiological ED alsoItalic text wake up with morning erections, according to the CU article. — Preceding unsigned comment added by 67.206.184.166 (talk) 22:33, 20 November 2011 (UTC) [edit shifted and reindented to retain threading -- 203.82.66.198 (talk) 01:23, 21 November 2011 (UTC)]

Just as a comment, I think it might matter what you sleep on. Specifically, I found it practically unworkable to sleep on an air mattress while camping, because it had an effect that seemed to verge on priapism (including the lack of real arousal). Seriously it seems better to sleep on the ground than put up with that ... but I didn't actually find medical discussion about this. Wnt (talk) 04:16, 21 November 2011 (UTC)

For possible help see Ingrid Bellamere's report. N.B. The link is for information and not recommendation. Cuddlyable3 (talk) 19:03, 22 November 2011 (UTC)

Relativistic attraction of current-carrying wires

Let us imagine a situation where we have two parallel current-carrying wires with current pointed in ${\hat {y}}$ direction. Let us idealize this situation by considering a line of electrons moving in the $-{\hat {y}}$ direction with a velocity $v$ (no wire, just movement of negative charges, and negative to take into account for conventional current). As is well known, the two wires will attract each other. Now, let us consider us in a new reference frame of the same situation where relative to our old reference frame we are moving in the ${\hat {y}}$ with velocity $v$. Now our electrons appear to be stationary charges, and since we are considering solely negative charges, the will end up repelling. My first question is: why does a change of reference frame change whether the wires attract or repel?

The movement of these charges will form a magnetic field by the equation $B={\frac {\mu _{0}v\lambda }{2\pi r}}$ for linear charge density $\lambda$ as $I={\dot {q}}=v\lambda$. Now, this magnetic field will reach the other wire and cause an attractive force towards the other by the Lorentz Force ${\vec {F}}_{B}=q{\vec {v}}\times {\vec {B}}$ and thus on a single charge we have $F_{B}={\frac {q\mu _{0}v^{2}\lambda }{2\pi r}}$. In our new reference frame, the electric field of one wire is given by $E={\frac {\lambda }{2\pi r\epsilon _{0}}}$, and thus the force on one charge is given by ${\vec {F}}_{E}=q{\vec {E}}$ and thus $F_{E}={\frac {q\lambda }{2\pi r\epsilon _{0}}}$. Even though I know the two forces are technically pointing in the same direction, for fun I decided to set $F_{E}=F_{B}$. What resulted was $v={\frac {1}{\sqrt {\mu _{0}\epsilon _{0}}}}$, which I recognized as the speed of light/speed of propagation of electromagnetic waves. My second question is: Why is that so and what relevance does the speed of light in the $\pm {\hat {y}}$ direction have in this situation? — Trevor K. — 04:38, 20 November 2011 (UTC) — Preceding unsigned comment added by Yakeyglee (talk • contribs)

"My first question is: why does a change of reference frame change whether the wires attract or repel?" Now, I'm neither a physicist, or a mathematician, so I can't claim to understand the question in detail, but I think that there is an underlying assumption there that needs further investigation. Do you have any empirical evidence that your "reference frame change" actually affects "whether the wires attract or repel"? I can't help thinking that this is on the face of it somewhat implausible. Still, what do I know?... AndyTheGrump (talk) 04:58, 20 November 2011 (UTC)

Yes, you're right in that regard. It seems fishy to me as well, which is why I felt the need to ask it. This is only the result of the equations and relationships of electromagnetism that I am familiar with, and it seems to form a result that contradicts itself. — Trevor K. — 05:22, 20 November 2011 (UTC) — Preceding unsigned comment added by Yakeyglee (talk • contribs)

A line of moving electrons is not equivalent to an wire carrying a current because the wire is electrically neutral but the line of electrons isn't. Dauto (talk) 06:37, 20 November 2011 (UTC)

I think you overlooked that the electric repulsion is present in all frames, and it's always larger than the magnetic attraction (becoming equal as v → c, as you observed). So these "wires" repel each other with respect to any frame. They do repel more slowly at high speeds, by a factor of γ. -- BenRG (talk) 06:43, 20 November 2011 (UTC)

And if you do take wires into account, i.e. you consider electrons moving through a stationary positive ion lattice (then there is no electrical repulsion since the charges cancel), you will get positive ions moving through a stationary electron lattice in the other frame 83.134.178.103 (talk) 08:16, 20 November 2011 (UTC)

There might be an electric repulsion or attraction in a referential other than the wire's referential. Dauto (talk) 15:10, 20 November 2011 (UTC)

Thers an article Relativistic electromagnetism that may answer your questions--78.148.128.218 (talk) 20:55, 20 November 2011 (UTC)

optic nerve damaged and loss of vision

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis, prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the Reference Desk's talk page.

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis or prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the Reference Desk's talk page. --~~~~

→Στc. 07:12, 20 November 2011 (UTC)

I think it is appropriate to point out that Wikipedia provides some information about the optic nerve and optic neuropathy. And ethics should compel us to urge anyone with recent vision loss to seek medical help quickly: purely as an example, note the usefulness of corticosteroids when given quickly for treatment of anterior ischemic optic neuropathy. Wnt (talk) 04:04, 21 November 2011 (UTC)

Proof?

In [12] interview, I read a part that said "Nobel laureate Eugene Wigner believed that observations determine existence, and observations require a conscious mind, and hence the existence of the universe meant that there was a cosmic consciousness permeating it. In some sense, he was offering this as a proof of the existence of God." Although there's some difficulty in equating "cosmic consciousness" and God, it seems quite reasonable, is there an article on this in Wikipedia?Are there any atheist answers to this kind of proof? — Preceding unsigned comment added by Irrational number (talk • contribs) 14:45, 20 November 2011 (UTC)

The part "existence = consciousness" is kind of weak. You don't need an atheist to dispute this. 83.37.188.63 (talk) 15:04, 20 November 2011 (UTC)

It's actually "existence=>consciousness" which is kinda different...--Irrational number (talk) 15:11, 20 November 2011 (UTC)

"I am, therefore I think"? Isn't that putting Descartes before the horse? Mitch Ames (talk) 12:20, 21 November 2011 (UTC)

Most physicists don't agree with Wigner's opinion on the topic so atheists may simple point out that this is a controversial interpretation held only by a small minority of physicists. Dauto (talk)

He wasn't expressing an original thought. He was repeating the Vedanta, which he had been studying for a while. -- kainaw™ 15:48, 20 November 2011 (UTC)

I could be wrong, but I don't think the Vedanta says anything about the collapse of the wave function. --Mr.98 (talk) 15:55, 20 November 2011 (UTC)

Perhaps you are REALLY reading into the quote in the question. I don't see anything at all about the collapse of the wave function in it. -- kainaw™ 21:24, 21 November 2011 (UTC)

See also Immaterialism. Deor (talk) 17:34, 20 November 2011 (UTC)

The main issue here seems to be whether a non-materialistic science can actually work and to what extent consciousness be incorporated into the equation – human consciousness seems to have a direct partly-observable effect only at very small scales, ie. the Quantum Zeno effect. Take a look also at theory of mind, Integral humanism (India) and Ghandi's Seven Blunders of the World: science without humanity. ~AH1 ^(discuss!) 20:33, 20 November 2011 (UTC)

The Quantum Zeno effect is in no way related to human (or any other) consciousness. Any device capable of determining whether the quantum pot has boiled will lead to the effect. Of course, nobody will know about it if nobody reads the device, but that's as meaningful as saying that nobody will know that a tree fell if nobody was watching the tree.

Also, I think that "science without humanity" means using science to pursue inhumane goals. I doubt Gandhi meant to imply that scientific laws would be invalid if humanity didn't exist. --140.180.3.244 (talk) 01:25, 21 November 2011 (UTC)

There's no consciousness effect in quantum mechanics. There's a phenomenon called quantum decoherence which manifests itself in experiments as the watched-pot effect (aka quantum Zeno effect), but it doesn't require lab equipment built by humans, much less "conscious observation", to operate. It operates in any thermodynamically irreversible system.

If God was watching everything, we'd know about it, because of the aforementioned watched-pot effect. If there is a God, he's not looking, at least not in the quantum sense. Wigner effectively believed that God was looking in a classical sense (looking at the world at a large scale, not at the details). The idea that there has to be a Prime Observer because nothing can exist without being observed is almost the same as the first cause argument, and the rebuttal is the same.

Michio Kaku is technically a physicst, but he has no reputation in the field. In practice he's a full-time media personality. He says dumb things all the time. Wigner was a prominent physicist, but he had the excuse that it was early in the history of quantum mechanics and it wasn't understood as well as it is now. -- BenRG (talk) 05:56, 21 November 2011 (UTC)

Tsunami

Im going to the Canaries for Xmas and New year (2 weeks). What is the probability of the Cumbre Vieja fault opening up and causing me to get hit by the megatsunami? --78.148.128.218 (talk) 21:10, 20 November 2011 (UTC)

It's similar to the probablity that your plane will crash. Which in turn is a lot lower than the probability that you'll suffer a deadly accident while driving to the airport. Count Iblis (talk) 21:16, 20 November 2011 (UTC)

Actually I would put that as a lot less than the likelihood of the plane crash, more like the chance of being struck by lightning and winning the lottery. Mikenorton (talk) 21:27, 20 November 2011 (UTC)

On this occasion Count Iblis I have to disagree with you. As we (anybody) can't quantify the probability that the local activity 'might' cause a submarine slippage (there ain’t no data) so we can't compare it to any other probability of risk. The Lake district is a nice place to go and it is a long way above sea level.--Aspro (talk) 21:33, 20 November 2011 (UTC)

Read this as to why the risk is much less than some people would have you believe and it is something that some geologists do spend there time trying to put numbers to. Mikenorton (talk) 23:20, 20 November 2011 (UTC)

@Aspro, are you being gently ironic in some way when you compare the Lake District and the Canary Islands in December/January. I go along with Count Iblis, the chances are vanishingly small. Richard Avery (talk) 08:13, 21 November 2011 (UTC)

If any quantifiable probability of a megatsunami swamping the Canaries were known it would be reflected in the price for Travel insurance. Cuddlyable3 (talk) 00:47, 22 November 2011 (UTC)

Crystal Fusion Turbine

I've got a wacky idea for a fusion power plant, so could you'll please point out the obvious flaw?

We know that Piezoelectricity can create surprising large electrical fields over small distances. So this design uses crystals that are rubbed against each other to build up strain that is suddenly released as they "snap back".

This field is then applied to liquid water flowing past the crystals, which by the Self-ionization of water has a tiny fraction of free protons that are accelerated 17 times as much as Hydroxide ions by the same electric field.

These crystals have a large proportion of lithium and boron, which the protons slam into, releasing alpha particles in Aneutronic fusion.

The alpha radiation is contained inside the device and used to boil the rest of the water which is then fed through a steam turbine connected via a shaft to the disks to which the crystals are attached. (The shaft is also connected to an electrical generator or other process to extract the energy for useful purposes.)

The steam then goes through a radiator and condenses back into water which is then pumped back into the device via a water turbine that is connected to the same shaft.

So basically this is a Jet engine, with the combustion chamber replaced by the fusion crystals.

And it doesn't work because what? Hcobb (talk) 21:37, 20 November 2011 (UTC)

Because the Klingons have cornered the market in Dilithium crysyals? Actually, this sounds no wackier than some of the other cold fusion devices being touted around currently. Even if it doesn't work, you could probably earn a few dishonest bucks by claiming it did, and advertising for 'investors'... AndyTheGrump (talk) 21:50, 20 November 2011 (UTC)

I'm not a physicist, but I'm dubious you can scale the crystals up to the size that would be necessary to generate enough protons to generate enough aneutronic fusion to boil water. Without knowing some basic numbers here — the strength of the field you'd, the likelihood of the protons being accelerated, the likelihood of the protons causing aneutronic fusion — it's hard to know exactly how impossible this is, even barring any actual physical errors in the conception (which I'm not qualified to identify). You'd need at least back-of-envelope numbers to even start thinking this made sense. Without those at hand, any kind of energy generation scheme sounds plausible (I rub my feet on the carpet, generating static electricity; I touch a door knob; the door knob connects to a device that uses the current to boil water; steam goes through a turbine; etc.); with them, it becomes clear what isn't ever going to work... --Mr.98 (talk) 00:12, 21 November 2011 (UTC)

This is a creative scheme, but I'm having trouble getting past the first step. According to that piezoelectricity article, the crystals can build up "thousands" of volts. Now even protons properly accelerated with millions of volts in an evacuated chamber are hard to get to fuse with stuff, so I don't see how you have enough power to play with. Of course, if you can start fusion, then the rest becomes very interesting.

I'm vaguely remembering something about a miniature neutron source (I think) that came out ten years ago - is this it? ("Rossi"?) [13] Maybe this is in some way related, but if I remember right the problem was that didn't actually produce very many neutrons for the power input. Wnt (talk) 00:38, 21 November 2011 (UTC)

Requested ref: Pyroelectric fusion Hcobb (talk) 03:27, 21 November 2011 (UTC)

Repeat trauma

Suppose a person receives a gunshot wound in the upper arm (a through-and-through with a full metal jacket round that does not break the bone or sever any nerves), and then three or four days later gets hit with the flat of a propeller blade in the exact same spot. Can this cause any significant complications (aside from the fact that it will hurt like hell)? DISCLAIMER: This is NOT A REQUEST FOR MEDICAL ADVICE. (Also note that the victim gets hit with the flat of the prop blade, NOT the sharp edge -- if it had been the edge, then it's obvious that the victim could end up minus an arm.) 67.169.177.176 (talk) 21:46, 20 November 2011 (UTC)

What -oh-what has prompted you to ask this question? From what context do we approach this? Are you researching for a novel?--Aspro (talk) 22:23, 20 November 2011 (UTC)

Yes, you're right on the money. Specifically, I intend for one of my characters to get shot while escaping from a hostile area after force-landing there, and then a few days later to get struck by the prop blade while hand-propping the engine (the plane's electrical system having been partially sabotaged in a way that is very hard to detect). 67.169.177.176 (talk) 23:30, 20 November 2011 (UTC)

Consider, from your own possible personal experience, that a wound that starts to heal, and then gets re-opened, will take longer to heal than just the one wound. And obviously, anytime a wound is (re-)opened, there is a risk of (further) infection. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:34, 20 November 2011 (UTC)

Am I to understand that the major complication is the risk of infection? 67.169.177.176 (talk) 01:30, 21 November 2011 (UTC)

It might be easier if you told us the outcome that your plot wanted, and we could see if a plausible medical explanation can be generated. TenOfAllTrades(talk) 23:35, 20 November 2011 (UTC)

That's not how I work -- I try to keep it realistic as much as I can. No point stretching the limits of plausibility for just one little episode. 67.169.177.176 (talk) 01:28, 21 November 2011 (UTC)

The outcome is: he gets the Girl – dummy :-)

What era is this set in? If its an ancient Cessna 152 with a fixed pitch -it will slice. An modern turboprop on full pitch (slap-mod) will suck the hero in to the prop and the natives will be able to enjoy long-pig stew for the rest of the week. Should he however, be standing behind the prop he will be blown a**** over t** and away from it. John Wayne was always getting shot in the shoulder and trampled by horses – can't you work that sort of scenario into the story instead? (it made him rich) PS. If doing a hand swinging start, he needs a leather glove. Aluminium props often have little nicks, which will cut into the the naked hand. Also, you could add realism by pointing out that 'contact on' is really 'contact off '– the electrical circuit is shorted to make it safe. For this reason and in reality – both swinger and pilot – must always assume that the ignition circuit is ALLWAYS LIVE in case of a bad shorting contact. Point out too that the fuel should be coloured blue (aviation gasoline) but as it isn't, it means he's running on 'regular gas' syphoned from the baddies limousine, (black, they always drive black limousines) etc., etc., etcetera.--Aspro (talk) 01:04, 21 November 2011 (UTC)

This is set in the modern era, but the aircraft in question is a prehistoric Electra 10-E with 550-hp Wasp engines and hydraulically-operated constant-speed propellers. Hope that helps. 67.169.177.176 (talk) 01:24, 21 November 2011 (UTC)

Which brings up the point that the Wasp engine CAN actually run on automotive gasoline if need be (yes, it's THAT ancient). However, this won't be the case here, because there's NO WAY you could fill up an Electra's 1100-gallon fuel tanks with fuel siphoned from the bad guys' limo. 67.169.177.176 (talk) 01:34, 21 November 2011 (UTC)

Also, as an aside, I don't think it's possible to hand-prop a turbine engine -- the cranking RPM's are just too high and the rotational inertia too big. 67.169.177.176 (talk) 01:36, 21 November 2011 (UTC)

Cumbre Vieja

Hi. Does there exist any geological evidence on the coasts of eastern North America, northern South America, the Caribbean, Europe, Africa, the Mediterranean (less reliable), etc. for a large tsunami across a wide area that coincides with postulated past occurrences of submarine landslides on the flanks of La Palma, El Hierro, or any other of the Canary Islands, dated using such methods as those used for climate proxies or other mud core sample data, or using C-14 dating, or other methods, that provides close correlation between the dates? Thanks. ~AH1 ^(discuss!) 22:33, 20 November 2011 (UTC)

The most recent landslide on the Canaries dates at 15,000 years age from El Hierro and the average repeat interval for such events is about 100,000 years (with a large spread). More details here. Nothing on tsunami deposits yet, still looking. Mikenorton (talk) 23:35, 20 November 2011 (UTC)

No, nothing on such deposits, and people are certainly looking. Plenty of examples of near-field tsunami deposits around groups of volcanic islands though, just not transoceanic ones. Mikenorton (talk) 23:58, 20 November 2011 (UTC)

November 21

Methods to measure change

Can someone suggest a method or two one might be able to use to measure the amount of change on an object? Any help would be great! 174.93.63.116 (talk) 02:02, 21 November 2011 (UTC)

Easy enough -- take the change off the object, sort the coins by denomination and count them. Or did you mean something else besides change (like charge)? 67.169.177.176 (talk) 02:51, 21 November 2011 (UTC)

I think the appropriate instrument is probably a typometer - which was of course named after the well-known astronomical misprint Typo Brahe ;-) AndyTheGrump (talk) 04:11, 21 November 2011 (UTC)

Make a measurement before, and a measurement after the change. Then you can take the difference or the ratio of the two readings. If you want to measure charge, you could put the object in a hollow conducting sphere, measure the voltage and divide by the capacitance of the sphere, which can be calculated by its size. Alternatively you could discharge the charge though an integrating ammeter and get a readout. Graeme Bartlett (talk) 05:58, 21 November 2011 (UTC)

(Edited to add: If you intended to type "charge" rather than "change, then) "An Electrometer would be the obvious instrument, unless you are supposed to conjure up some improvised method. Otherwise you might measure the attraction to a charged or uncharged object hanging from an insulating thread and use basic physics to calculate the force from the angular displacement, then the charge from the force. Possibly you could transfer the charge to a capacitor of known capacitance, ten measure the charge on the capacitor with a high impedance voltmeter. A simple formula then tells you the charge on the capacitor. Edison (talk) 20:10, 21 November 2011 (UTC)

Braeme and Edison assume the OP meant to write charge instead of change in both the question and its title. However if the intended meaning was change in mass then a different answer is needed. Cuddlyable3 (talk) 00:29, 22 November 2011 (UTC)

True, but the hint was the preposition. Mass is seldom described as "on". Dbfirs 07:39, 22 November 2011 (UTC)

Marburg virus

I just read the hot zone book. This virus seem to be around for almost half a century now. It's very lethal and i wonder if we have found a cure for it yet?Trongphu (talk) 05:24, 21 November 2011 (UTC)

Marburg virus disease#Treatment says there is no current effective therapy. Clarityfiend (talk) 05:55, 21 November 2011 (UTC)

Man i feel like we, humans, kind of get left behind in medicine. There are some lethal diseases that have been known for ages and we haven't figure out how to cure it and where they come from. Lucky that those diseases didn't spread worldwide, otherwise there is possible that most of the people in this entire world get wipe out.Trongphu (talk) 03:06, 22 November 2011 (UTC)

Actually, that article should be updated: there's an experimental vaccine that can be used as a treatment if used in time: [14] Acroterion (talk) 03:53, 22 November 2011 (UTC)

... in monkeys. So you're still outa luck. Clarityfiend (talk) 04:26, 22 November 2011 (UTC)

True, in monkeys, but it's a matter of time before it's used in humans, assuming the treatment is found to be non-toxic to humans (and most people would run the risk, I suspect, if the alternative was developing Marburg symptoms). Acroterion (talk) 04:59, 22 November 2011 (UTC)

"right-hand-side" hypothalamus?

i just read in "biological substrates of human sexuality" that activation of the "right-hand-side" hypothalamus initiated sexual arousal in males.

what is the meaning in "right-hand-side" hypothalamus?, is it the right-wing appearance of the hypothalamus?, or maybe the writer means that it's the hypothalamus of people who's brains are organized in the "right-hand-fashion" ?.. thanks. — Preceding unsigned comment added by 81.218.145.251 (talk) 09:33, 21 November 2011 (UTC)

As you will see from this page, the hypothalamus has two lobes. --TammyMoet (talk) 13:14, 21 November 2011 (UTC)

We don't have an article called biological substrates of human sexuality, so I don't know what the OP was reading. Male arousal is associated with activity of a small portion of the hypothalamus called the sexually dimorphic nucleus, which exists on both the left and right sides of the brain, but I'm not aware of any publication that says the two sides differ from each other. Looie496 (talk) 16:38, 21 November 2011 (UTC)

Object in the night sky

At work, middle of the night and there is a black and white monitor to my right that shows the end of the runway. In the bottom right of the monitor is a white blob that is actually a red light on top of the VOR/DME and is the only thing the monitor sees in the dark. Earlier I noticed that slightly to the lift and above the VOR/DME there was another light source. I assumed it was a snowmobile but thought it was moving to slowly. I went out to get a better look and realised it was in the sky, a reddish colour and moving slowly northwest in a straight line. I came back in started up Stellarium (computer program) to see if I could identify the object but wasn't able to find anything. It was moving too slow to be a satellite and was too bright. Any ideas what it was I saw? BTW it is obvious that it's the same object a co-worker saw last week and actually filed a report on it as a UFO. However, I'm not thinking of the opinion that it is a UFO. CambridgeBayWeather (talk) 13:23, 21 November 2011 (UTC)

Jupiter has been up the last few weeks; it will be visible as a very distinctive and bright object in Northern Canada and most of the Northern hemisphere in the middle of the night. If you have binoculars, try to spot the object again; if you can see four moons, you're certainly looking at Jupiter... if you can't positively identify the object, you could be looking at "something else.". Nimur (talk) 15:59, 21 November 2011 (UTC)

Jupiter wouldn't visibly move (well, it moves with the whole night sky as the Earth rotates, but I wouldn't expect the OP to have noticed that movement with the naked eye). --Tango (talk) 18:57, 21 November 2011 (UTC)

Since you're at an airport, the obvious answer would be that it was an aeroplane, but I'm guessing you wouldn't make that mistake! It could be a very distant plane, though - that would explain it's very slow movement. What did it look like? Was it a single point of light? Or a diffuse glow? --Tango (talk) 18:57, 21 November 2011 (UTC)

By definition it remains a Unidentified flying object because you can't identify it. Aircraft such as the Skyship 600 move slowly. At night they are often internally lit with bright halogen lamps to show the advertising on their translucent skin. In windy conditions one can see that their flight is slightly erratic as they get blown around. If so it will be fitted with a transponder which can be picked up on amateur equipment such as this: [15]. Which gives a display like this: [16]. A scanner tuned to the local air traffic feq. may also pick up the chit-chat with the craft and ATC. --Aspro (talk) 18:53, 21 November 2011 (UTC)

Could it have been a stray Chinese lantern? --TammyMoet (talk) 19:20, 21 November 2011 (UTC)

If it was a Chines lantern wouldn't it have been a weddish colour ?--Aspro (talk) 19:45, 21 November 2011 (UTC).

You could be seeing the early proving flights in your area connected with this airship.[17]. I think air certification takes a minim of 5,000 flying hours, so it would be around this time when you see it appear in the skies -if the contract is to be signed on time. You could phone them up, ask to be put through to their pubic relations department for confirmation. Should this be right, you can ask for some publicity material/ glossy brochures (possibility of complimentary fights?) etc., which they will be happy to send you. PR departments love people taking an interest, that is the whole reason for their being.--Aspro (talk) 19:41, 21 November 2011 (UTC)

I did think of Jupiter but Stellarium showed it right on the horizon, a bit too low. Also I couldn't see any moons around it with binoculars. I did wonder if it was an aircraft. We see 2-3 a month flying the great circle route but most of those are north to south and tend to be flashing lights rather than a glow. I'd forgotten about the airship but I don't think they will have one built until 2012, Hybrid Air Vehicles. The video of the model looks interesting, here I think but that's not working right now. It could have been a non-commercial aircraft. CambridgeBayWeather (talk) 21:11, 21 November 2011 (UTC)

Betelgeuse? Count Iblis (talk) 03:51, 22 November 2011 (UTC)

If its movement is obvious to the naked eye over the course of a few minutes or less, (and it doesn't zip across the sky in a couple of seconds or less) then it's nothing astronomical. It could possibly be a large artificial satellite like the International Space Station, but they only appear reddish for a few seconds when they're fading while moving into the Earth's shadow (to them it's like sunset).

If a colleague has seen the same thing it's unlikely to be a random event like a Chinese lantern release. I imagine you'd know about any weather balloon releases in the area!

My money would be on an aircraft of some kind. From my own experiences (living near RAF Leuchars and visiting the vicinity of other such bases) your description fits very well distant military aircraft taking off and using their afterburners. If the orientation of runways and flight paths happens to be right, you can see these many miles away, well beyond where you would hear their sound, and because they're be moving almost directly away from you they appear slower than you'd expect an aircraft to be. Can you establish whether there's a (military) airfield in that direction within, say, 25 miles? {The poster formerly known as 87.81.230.195} 90.197.66.40 (talk) 04:21, 22 November 2011 (UTC)

I thought about Betelgeuse but it looked to far south and wasn't moving on Stellarium. I should have mentioned where I live, Cambridge Bay, and work, Cambridge Bay Airport, 69°06′29″N 105°08′18″W. The closest airport would be Gjoa Haven, 68°38′08″N 095°51′01″W, and it's 350 km (220 mi) east. To the southwest is Kugluktuk, 67°49′00″N 115°08′38″W, about 450 km (280 mi) and Ulukhaktok, 70°45′46″N 117°48′22″W, a bit further away to the northwest. The only airports with a military presence would be Iqaluit Airport, 63°45′23″N 068°33′21″W, Rankin Inlet, 62°48′41″N 092°06′57″W, and Yellowknife Airport, 62°27′46″N 114°26′25″W, which are forward operating bases for the McDonnell Douglas CF-18 Hornet. Although not stated in the article I get the impression that the afterburner would not be on for 15-20 minutes which was about how long I saw the object. The balloon release is at 11:15 Z and 23:15 Z. They look nothing like what I saw and can't be seen in the dark. Also by the time I posted this the balloon had burst and the guy who released it had just called me. CambridgeBayWeather (talk) 05:30, 22 November 2011 (UTC)

The airships to meet this order won't be built until next year but I'm talking about the proving flights that take place (with exiting airships) before production begins. Cambridge Bay Airport has an SSR and whilst this object is probably well out of its range, the operators are likely to be aware of what type of air traffic is operating further out. The existence of airship flights, moorings sites, (or other things that could account for this sighting) etc., might even be mentioned on the local NOTAMs. They should be able to tell you who is walking about airfield with an up-to-date copy stuffed in his shirt pocket. In your area I would guess that helicopters have to fly at just above ground level in some poor visibility conditions. A moored airship would present a very unpleasant surprise to these pilots so such sites would certainly be mentioned on NOTAMs. --Aspro (talk) 10:04, 22 November 2011 (UTC)

We don't have a Secondary surveillance radar, in fact because we have a Remote communications outlet about .5 mi (0.80 km) away we don't even have the Aircraft emergency frequency (121.5). I work at the Community Airport Radio Station, that's for the Yukon but its the same as us. We check the NOTAMS daily and there hasn't been anything on there. The object was not making any noise that I could hear so it would have had to have been more than 5 NM (9.3 km; 5.8 mi) out and that puts it beyond the Mandatory frequency. If a mooring for an airship had been built it would have probably been big news and put up some place easily accessible like Hope Bay Aerodrome. And it was back again this morning in what appeared to be the same place. CambridgeBayWeather (talk) 13:35, 22 November 2011 (UTC)

I was just leaving work and as I drove away from the airport I was staring at the old DEW line site. They don't have a SSR but they have or did have a long range radar, see List of DEW Line Sites (search for CAM-MAIN) and here. But they no longer monitor it onsite and haven't for at least 16 years. It is monitored remotely but I'm not sure where, possibly CFB North Bay. CambridgeBayWeather (talk) 14:48, 22 November 2011 (UTC)

According to this [18] the Department of National Defence has long range radar and short range radar based at Cambridge Bay still operating in 2008. As you say it is likely to be unmanned these days and since 9/11 it is likely to be difficult to get anything out of them anyway. I don't know if they are official allowed in Canada are but I'm wondering if someone has a 'complete and detailed' list of the frequency allocations. A scanner (if they are legal where your are) could then be set to sweep those freqs automatically, looking for radio traffic. Might be worth putting up a request for sightings on your radio stations notice board. If you can get some fool interested enough who has a night-rating, then maybe they'll go up and chase it – then sell the shot footage to a news organisation. Even if it turns out mundane it should make a good story. As far out as 5 NM, the navigation lights should have been easily visible with binoculars so I agree it was likely much further away (presuming it to be a terrestrial aircraft). --Aspro (talk) 15:11, 22 November 2011 (UTC)

Thinking about it. If there are enough curious witness to this same phenomena, then the airport manger might find that justification alone to make inquiries to the North Warning System – just for good public relation reasons and the fact that its distracting his employees :-) Also, from his point of view as a PHB, he wouldn't like to think that his subordinates has discovered there is something that he does not have an answer for. --Aspro (talk) 16:32, 22 November 2011 (UTC)

Now that I've slept on it I suspect that Edmonton ATC can monitor the radar. The Canada Flight Supplement has all the frequencies and I didn't think about it until you mentioned a scanner. All I need to do is open the Airport Managers office and turn his scanner on. CambridgeBayWeather (talk) 22:41, 22 November 2011 (UTC)

Brain size/body size and intelligence

Is there any correlation between brain size and body size when it comes to intelligence in living creatures? 58.109.41.190 (talk) 14:03, 21 November 2011 (UTC)

Yes, but like all things biological it is complicated and there are caveats. But check out our article on brain-to-body mass ratio and the related-but-more-useful encephalization quotient. --Mr.98 (talk) 15:24, 21 November 2011 (UTC)

Certain Mormyridae (a fish) have higher Brain-to-body mass ratio than man, followed by woman. Cuddlyable3 (talk) 00:20, 22 November 2011 (UTC)

Human men and women have mostly comparable brain-to-mass ratios, though with very small men or women the results get skewed. I wouldn't read a lot into that, though. As stated, this is as best a rough metric. And with very small things (birds in particular) the results are really off. Ditto that particular fish. But in general there is a correlation. The EQ ratio is a better correlation, but it too is just a hand wavy correlation, not an absolute law. --Mr.98 (talk) 12:00, 22 November 2011 (UTC)

Simple explanations for the recent neutrino experiments

There are a number of simple explanations coming to my mind about the OPERA neutrino experiment which apparently produced faster-than-light neutrinos. I wonder because I couldn't find them in the discussions and articles about it.

First of all, I understand this does not mean a significat faster than light travel, so we would not travel 100 times faster than light with it... The difference was only a few nanoseconds, so what if...

1. we measured the speed of light wrong? The definition is "speed of light in vacuum", but space is not a perfect vacuum. What if neutrinos travel exactly or just below the speed of "light" (as defined by relativity), but photons travel a little slower? We all know light travels much slower in certain substances, and that neutrinos react much more weakly with matter than photons. Did we measure the speed of light accurately? Was it in perfect vacuum? Is vacuum without any matter actually perfect, or maybe there is something undetectable or barely detectable like dark matter or something similar, which photons (even if barely) interact with, and neutrinos don't ?
2. The speed of light changed slightly since the last time we measured it. Who kwnos, expansion of the Universe, some large blob of dark matter passing through our galaxy, God just being in the mood of changing a cosmological constant, or basically any sensible or silly explanation we don't understand yet? We know that the speed of light was not always constant, because the known Universe is bigger than its age would indicate, so once in the past it had to expand faster than the current speed of light, assuming our model of the Big Bang is not horribly wrong.
3. Is it actually possible to transmit information with this experimet? If not, then it's just one of several known cases of something traveling faster than light.

Is there something which might be plausible, and if not, where am I wrong? — Preceding unsigned comment added by 91.23.232.169 (talk) 18:39, 21 November 2011 (UTC)

There have been lots of experiments to measure the speed of light and they have all agreed, so I doubt that is the issue. If we were get our vacuums wrong then we would be getting them wrong in different ways each time, so we wouldn't get the same answer. If the speed of light is changing that quickly, then, again, we wouldn't keep getting the same answer. I can't see why you couldn't transmit information with these neutrinos (although the bit rate would be incredibly low!) - the experiment seems to be showing that the individual neutrinos are actually travelling faster than light, this isn't just a group velocity vs phase velocity thing. --Tango (talk) 18:52, 21 November 2011 (UTC)

How do whe know they are the same individual neutrinos, and not just some case of entaglement or something similar? --91.23.206.55 (talk) 18:57, 21 November 2011 (UTC)

You can measure the energy and origin direction of the neutrino, which tells us that they are from CERN. CERN creates them in small bunches. Given that we know when they are created, and how far they have to travel, we can predict when they will arrive, but the ones that were observed appear to have arrived a little too soon. Dragons flight (talk) 19:24, 21 November 2011 (UTC)

So if we used it in a practical way to transmit information, how exactly could it send infomration to its own past? Af far as I know that's the biggest paradox with FTL communication. --91.23.206.55 (talk) 19:36, 21 November 2011 (UTC)

Tachyonic antitelephone shows a general construction (subject to several untested assumptions about how faster than light travel works). In order to transmit information into your own past using this system you require a physical relay that is moving relative to the sender at nearly the speed of light. If the neutrinos travel at (1 + 2.5×10⁻⁵)c then the relay must move at least (1 - 3×10⁻¹⁰)c. Not very practical, but physically possible. Dragons flight (talk) 19:57, 21 November 2011 (UTC)

If there were something (call it dark matter, dark energy, aether, or anything) which slightly interacts with photons but not with neutrinos, that could still mean that all our measurements of the speed of light are incorrect, and still give the same results. So the "speed of light" might be better represented by the speed of neutrinos, and photons are just a little slower? Has the speed of light ever been calculated theoretically, without actually measuring photons in some way? --91.23.206.55 (talk) 19:45, 21 November 2011 (UTC)

As discussed in Speed of light#measurement, the speed of light has been measured both directly (by time of flight) and indirectly via measuring other physical properties of light (e.g. simultaneous wavelength and frequency, permittivity / permeability of free space). Could all these properties be confused in some way? Maybe. But that's almost certainly a long shot compared to some other more mundane error in the OPERA result. Dragons flight (talk) 20:15, 21 November 2011 (UTC)

As speed of light I was referring to "c", as defined in special relativity, not the actual speed of photons. What if the two are not exactly the same, just very close? It might be a silly idea, but it seems more plausible to me than being able to send information to the past. --91.23.206.55 (talk) 20:51, 21 November 2011 (UTC)

Well, the most plausible thing is that this is an error of some sort, at this point. And divorcing c from the speed of light in a vacuum would make a perfect conceptual mess of SR. Setting c to be an arbitrary concept that is equal to the speed of light in a vacuum except with regards to neutrinos would be physically abhorrent. --Mr.98 (talk) 21:29, 21 November 2011 (UTC)

Not necessarily divorcing it. c would still remain the maximum speed limit, only that photons can only reach 99.999998% or similar percent of it, just like they move slower through water or glass. Maybe there is something in vacuum that does not make it 'perfect' vacuum. No one did ever create completely perfect vacuum, and even in the deepest space there is intertellar hydrogen and maybe other things we don't yet know. Or maybe photons interact weakly with "dark something" better than neutrinos? Neutrinos are famous that they can pass through light year thich solid lead, something photons cant quite do... Of course, it might be an error in the experiment, but it was repeated. A hoax is highy unlikely, with such a large number of scientists involved. A systematic error? Are there any plans to measure the speed of light again in the near future, maybe with specific regards on information gained from this experiment? --91.23.206.55 (talk) 21:47, 21 November 2011 (UTC)

The experiment was not repeated independently — the replication was done by the same team. All it did was rule out one of many sources of error. The experimental result is not in any way something accepted by most scientists as legitimate at this point. Nobody thinks it is a hoax. --Mr.98 (talk) 03:13, 22 November 2011 (UTC)

If the speed limit of general relativity is not equal to the speed of actual photons, then it would require most of our understanding of relativity to be revised. It would be as surprising as finding neutrinos that go faster than photons. Also, given the dozens of detailed tests of general relativity over the years, I would be very surprised if existing observations don't already exclude that possibility with a sensitivity substantially greater than the OPERA claim. Dragons flight (talk) 21:37, 21 November 2011 (UTC)

Well, it wouldn't really require relativity to be revised, necessarily; it could just mean that photons have nonzero (rest) mass. If I am correctly informed, that's inconsistent with a lot of what we think we know about particle physics, but not about relativity.

However the experimental upper bound on photon mass is pretty small. --Trovatore (talk) 01:46, 22 November 2011 (UTC)

4. Software error. Getting the time difference right is a tour de force. Two different clocks are involved, the neutrinos detected at CERN are given a time stamp using th clock there, the neutrinos detected at LNGS are given a time stamp using the clock at LNGS. You need to make sure that the clocks are synchronized, or at least be able to tell when an event happened according to the clock at LNGS when you know the time according to the clock at CERN.

Also giving a time stamp takes time, which one has to take into account. When neutrinos cause a reaction then that leads to an electronic signal, which travels through electric of fiber optic cables, at some node you add to it a signal that originates from the clock. But the time stamp given in this way will not be the actual time the neutrino caused the reaction, you will be off by the time difference between the time it took for the signal from neutrino detector to travel to the node and the signal from the clock to travel to the same node.

All such effects are taken into account automatically, but a small error somewhere can easily lead to a 60 ns error. Count Iblis (talk) 22:53, 21 November 2011 (UTC)

The guy who stamps the time on the neutrinos needs little teeny hands. --Trovatore (talk) 23:38, 21 November 2011 (UTC)

To help understand "small" error in context, light or any other electromagnetic signal travels 18 meters in free space during 60 ns. Cuddlyable3 (talk) 00:11, 22 November 2011 (UTC)

This just in. {The poster formerly known as 87.81.230.195} 90.197.66.40 (talk) 04:34, 22 November 2011 (UTC)

Can't say I'm terribly impressed. I mean, I'm certainly not an expert in this area, but to me it looks like just another theoretical reason why what has apparently been observed, can't be happening. But we already have plenty of those. What we need is an explanation for why what was observed was in error, or else a careful repetition of the experiment that either does or does not confirm the outcome. --Trovatore (talk) 09:16, 22 November 2011 (UTC)

Another good reason for doubtingf it is at these rates the neutrinos from SN 1987A would have arrived four years before the light. Dmcq (talk) 16:28, 22 November 2011 (UTC)

That is a good reason, but as OPERA neutrino anomaly#Previous measurements notes, SN 1987A's neutrinos were of a different type than OPERA's. As we can't definitively reject the hypothesis that different kinds of neutrinos travel at different speeds, SN 1987A doesn't necessarily invalidate the OPERA results. -- Finlay McWalterჷTalk 16:35, 22 November 2011 (UTC)

The difference that seems most interesting to me is that the SN 1987A neutrinos travelled through empty space, whereas these are moving through the Earth. Rampant Speculation: It's well known that matter can slow the speed of light that passes through it - is there any conceivable way it might also be able to increase it? I'd think it would have to be the matter, not just gravity or even electric fields, because the 1987A neutrinos would have gone through quite a few of those on the way here. But nuclei are only 1/(100,000)³ of the volume of matter, so the neutrinos would have to be doing more than just skipping across nuclei at a faster pace. Are they affected only by the super-strong electric field inside individual atoms, or reached by some weak-force effect that blossoms out from the nucleus? It does get more interesting the more it's replicated, but it's still probably some absurd but incorrect detail: GPS using the wrong shape for the Earth, incorrect estimate of the density and gravity field of the Earth at varying depths below the surface etc. Wnt (talk) 18:29, 22 November 2011 (UTC)

Oxide world

What will be the diffrent between an earh-like world that instead of 21% of oxygen, will have 100% oxygen in the air(of course)? Exx8 (talk) 20:10, 21 November 2011 (UTC)

If there were anything flammable, it would burn until either the fuel or the oxygen got completely or nearly completely consumed. Would our Earths atmosphere be composed of 100% oxygen, al life would end very quickly in a fiery death, maybe except some heat tolerant anaerob bacteria deep down under some volcanoes. --91.23.206.55 (talk) 20:12, 21 November 2011 (UTC)

There could be star systems where oxygen far exceeds the amount of the heavier elements. You may end up with a water world; or if hydrogen was somehow depleted, something even stranger made from solid oxygen. Graeme Bartlett (talk) 22:39, 21 November 2011 (UTC)

A 100% pure oxygen atmosphere seems to rule out there being any gaseous products of combustion. It also rules out all the life processes that depend on the Nitrogen cycle so if any life evolved on such a world, it would not be Life As We Know It. Visitors from Earth would be in danger of Hyperventilation on arrival and, if they survived (oxygen becomes toxic under pressure), Decompression sickness on leaving. Cuddlyable3 (talk) 23:59, 21 November 2011 (UTC)

Before life on earth there was very little if any "free oxygen", it's the 3rd most abundant element in the universe but it's highly reactive, so I doubt any planet would be "pure" enough to prevent any free oxygen from being bound up into other molecules. For one, the planet would need to have no hydrogen, or far less at least, which seems unlikely since hydrogen is the most common element. Oxygen#Occurrence touches on this a little. Vespine (talk) 01:47, 23 November 2011 (UTC)

Digestion of Monosaccharide

Hi, I would like to know: 1)Are all of the Monosaccharide sweets? 2)Are all of the Monosaccharide digestable? Exx8 (talk) 20:11, 21 November 2011 (UTC)

The first is answered in the lead section of our monosaccharides article. Maybe an answer to the second lies therein as well. Search, you should. --Ouro (blah blah) 21:23, 21 November 2011 (UTC)

1. (edit conflict) No, as stated in the third sentence of Monosaccharide, "Some monosaccharides have a sweet taste." Since some is not a synonym of all, that means that not all of them are sweet.
2. No, some monosaccahrides are fairly undigestible. See this google search, where you can find many references. --Jayron32 21:28, 21 November 2011 (UTC)

Sorry for ec-ing You, Jayron. --Ouro (blah blah)

Is there a sweet and non digestable one? Exx8 (talk) 23:45, 21 November 2011 (UTC)

Depending on how expansive your definitions of "monosaccharide" and "non-digestable" are, erythritol may be one example, as it "is 60–70% as sweet as table sugar yet it is almost non-caloric". -- 140.142.20.229 (talk) 02:44, 22 November 2011 (UTC)

Curiosity

i was watching curiosity with stephen hawking in discovery channel on Did god created the universe?, at one point they discuss on how can something came from nothing without divine intervention, turns out it is possible because of negative energy, and we sum up eveything in the universe, it will equal to zero. i read somewhere that nature tends to use as minimal energy as possible, for example the bee hive structure, (i hope its a good example), im not an expert but why is it then that unviverse began assuming that its more work rather than nothing?i hope somebody gets my question. MahAdik _usap 21:24, 21 November 2011 (UTC)

Other beginnings to consider apart from balance of energy is information/entropy and cause. Graeme Bartlett (talk) 21:51, 21 November 2011 (UTC)

First we have to agree on a definition of "God", but I assume here we all talk about the omnipotent God as in the three major Abrahamic religions, and not just some guys with super strength like in Greek or other pagan mythologies. For such an omnipotent entity anything is possible, so it is not in our capability to either prove or disporove it. It doesn't even require negative energy, an omnipotent God can just create anything, and can violate the laws of the Universe, like if you write a computer game, implement a cheat code, and you can create anything in that game out of nothing. Now comes an interesting part if some of your characters in that video game would gain sentience, and would start doubting that they are in a video game, and that their wold was created by a programmer... --91.23.206.55 (talk) 21:58, 21 November 2011 (UTC)

You bet. And then they would have many debates on whether there really is a Programmer, and if so, how would you prove it? Or could you? Maybe it would have to be based on faith. And instead of belief in one Programmer, there could be poly-progammerists who believe there are many of them. And so on. Nifty idea. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:26, 21 November 2011 (UTC)

Nifty idea? Disney already been there, done that.. Cuddlyable3 (talk) 23:38, 21 November 2011 (UTC)

Primitive men thought thunder was a god grumbling, medieval men thought god held up the Moon and there are still a few 19th century leftovers who think dinosaur fossils were made by a god to deceive us. As actual knowledge grows, the scope for godly intervention diminishes towards zero. The question about the source of the energy of the Universe need not be answered with superstition if one can visualize the system as an enormous loss-free resonant cavity. The sum of energies and mass stays constant, and can be called "zero" just because there is nothing to measure it against. However the flows of mass/energy exchanges are huge and chaotic enough at the microscopic level to give us curious experiences. Cuddlyable3 (talk) 23:33, 21 November 2011 (UTC)

Yes, part of the question is how you define "God". Discovery of an "architect" or at least a catalyst or a definite non-random origin does not automatically prove the veracity of any of our human gods, including that of the Abrahamic religions. Proponents of creationism and intelligent design often conveniently ignore the fact that when a watchmaker makes a clock, he isn't necessarily concerned with what happens to the clock, nor does he talk to the clock, or care what the fates of the gears in it ultimately are (though he may repair it every now and then). The shepherd analogy is also morbid in its irony - the shepherd nurtures his flock only because he benefits from them, and he may even eat some every now and then. Who knows, the entire universe may actually be something as mundane as a power source in some unimaginable higher reality. Designed, but no more special than the watch on your wrist.

As for polytheistic religions, they aren't necessarily merely superhumans, remember that in most polytheistic religions, the gods are personifications of natural forces. Replace Zeus with "lightning", replace Hephaestus with "volcano", replace Artemis with "moon", and you begin to realize that the mythologies are really simply stories about nature adapted to the human culture. Even the Abrahamic religions are in truth, polytheistic. They have two gods - god is the personification of human moral good, and satan is the personification of human moral evil. Religion is not unlike science in this regard, but instead of objective observations, they dress it up through the filter of human experiences. And thus why the Abrahamic god is male, lives in the sky, and has a mean temper. For an omniscient being, he now resembles a Middle Eastern culture human father simply because those were the limits of our imaginations and all that we knew back then. This is also why religions are sometimes hostile towards new discoveries, because it illustrates the inadequacy of their explanations and relegates their god to a god of the gaps. The unknown has always been a fertile blaming and attributing ground for religions (as well as science, except that science actually tests it out). Taking away the mystery weakens this. Interesting side-note: the forbidden fruit in Genesis is that of the tree of knowledge. That raises a lot of red flags. Since when was ignorance a virtue?

It is a very valid scientific question, however. The truth might actually be even curiouser. We still have yet to explain consciousness, for example. But practically, it really is something we do not possess the means to understand now and most probably ever.-- Obsidi♠n Soul 04:54, 22 November 2011 (UTC)

Note that it doesn't matter whether you think God created the universe, in any case you always end up with either something springing from nothing or something having always existed (whether the universe is that something or God is). StuRat (talk) 03:31, 22 November 2011 (UTC)

A way out here is to assume that the universe only exists in a mathematical sense. I.e. all that exists are abstract mathematical models. One such model describes our universe and us. According to the model describing our universe, the universe can be finite in time, but the description itself (which is what really exists), is timeless. Count Iblis (talk) 03:40, 22 November 2011 (UTC)

Well, rather the universe really exists, but all we as humans can do is create models of it. We have our personal model of the world, which allows us to interact with it in useful ways (like, our intuitive sense of how gravity works, or how a solid object will respond to manipulation, etc.), and there are also well developed scientific models which describe how the universe works. However, they are still all models; reality exists, but human perception is only capable of representing reality inside our minds (individually and collectively) as models, and as George E. P. Box so eloquently put it "All models are wrong, some models are useful". --Jayron32 03:54, 22 November 2011 (UTC)

Box meant All Quadratic polynomial models are wrong... and we should try to think outside the box. Cuddlyable3 (talk) 18:27, 22 November 2011 (UTC)

Measurement of sweetnewss?

In this article there is a table of how many sweetness there is in the metrials. How do they measure sweetness? Exx8 (talk) —Preceding undated comment added 23:50, 21 November 2011 (UTC).

The most common method is to give tasters samples with different concentrations and ask them to compare -- or just to ask how high a concentration it takes to detect the presence of the sweetener. Looie496 (talk) 00:07, 22 November 2011 (UTC)

If you are looking for a more scientific method, you may want to check the article on brix (sweetness units). I guess the table in the article you refer to should have included the type of units and not just numbers (not sure what unit the editor had in mind when making the table). If you find out, you can contribute by editing the article, or adding a post to its corresponding discussion page. DI (talk) 13:09, 22 November 2011 (UTC)

There is no unit. It is 26X sweeter than sucrose, 0.16X sweeter, etc. Rmhermen (talk) 15:02, 22 November 2011 (UTC)

Note that the Brix units don't report directly on sweetness but on sucrose (or total sugar, depending on the method and sample) content. Instead, they give the apparent concentration of sucrose – 1 Brix unit equals 1% sucrose – as derived from a physical measurement of density, refractive index, or optical rotation. Unless you're comparing Brix numbers for solutions containing the same sugars (in the same relative proportions), two solutions with the same Brix value can have very different levels of perceived sweetness. For example, a 2°Bx solution of sucrose will taste sweeter than a 1°Bx solution of sucrose—but that 1°Bx solution of sucrose will taste quite a bit sweeter than a 2°Bx solution of lactose. TenOfAllTrades(talk) 17:08, 22 November 2011 (UTC)

November 22

banana

Is banana not good for daibatic people? — Preceding unsigned comment added by 219.73.12.77 (talk) 03:31, 22 November 2011 (UTC)

Ripe bananas are relatively high in sugars compared to other fruit: [19]. But, it really depends on what you do with them. Just eating a whole bunch as a meal might be bad, but using one to sweeten your oatmeal or cereal is probably fine, since you are then using the banana in place of another form of sugar, rather than in addition to it. The banana has lots of nutrients in it which many other sweeteners lack, so in that sense it's a good choice. StuRat (talk) 03:37, 22 November 2011 (UTC)

Given the danger inherent in mismanaging your diabetes, if you have concerns about ANY food and its effect on your diabetes, please ask a doctor or other qualified medical provider, do NOT trust the advice of random people on the internet with your health. --Jayron32 03:50, 22 November 2011 (UTC)

They never said they have diabetes. StuRat (talk) 04:22, 22 November 2011 (UTC)

No, but on the off chance they are, we shouldn't be telling them that anything is OK without first consulting with a medical professional. If they die because your advice that something is "probably fine", well done! I'd rather err on the side of not killing people. --Jayron32 04:27, 22 November 2011 (UTC)

See http://www.askdrbernstein.net/.

—Wavelength (talk) 04:29, 22 November 2011 (UTC)

Spin of a massive object reaching relativistic speeds

So what would happen if the spin of a large object reached relativistic speeds? I will ask about the following two circumstances:

• A non-black hole object (e.g., a pulsar) which started to spin this fast. Would there necessarily be a lot of drag on the star because the inner parts could spin faster than the outer parts? What would be the result of the drag - a quick slow down?
• A non-charged black hole object, whose outer edges reached relativistic speeds due to the influx of matter? I'm inspired by this article [20] which describes the observation of a black hole whose spin at its event horizon is 800 rps (!). What would happen with the shape of the event horizon? Could this cause a naked singularity? Would the black hole also slow down due to its drag, or is this not possible due to the other relativistic effects?

71.58.69.237 (talk) 04:25, 22 November 2011 (UTC)

I'm no expert, but frame-dragging would be one result. Clarityfiend (talk) 10:32, 22 November 2011 (UTC)

See Kerr metric for a description of what happens in the black hole case. One notable feature of a rotating black hole is the presence of an ergosphere, within which spacetime is dragged around at a speed greater than the speed of light. There are overextreme Kerr solutions in which a naked singularity appears, but my guess is that such situations don't actually wind up existing in reality. Red Act (talk) 14:02, 22 November 2011 (UTC)

Wouldn't a "non-black hole" object rip itself apart at such speeds ? StuRat (talk) 15:09, 22 November 2011 (UTC)

I'd go more fundamentally, would this be even possible for a non-black hole object? What energies would be required for the spin-up? --Ouro (blah blah) 17:28, 22 November 2011 (UTC)

Gravitationally, a neutron star is capable of reaching a small fraction of a relativistic spin (e.g. 1-30% of c at the equator, depending on mass) without the rotation being so strong that it simply flies apart. The energy required is astronomical, but not entirely crazy, e.g. 1% of the energy emitted during a supernova. The fastest known pulsar, PSR J1748-2446ad, is actually believed to be moving at 24% of the speed of light at its equator. Dragons flight (talk) 18:03, 22 November 2011 (UTC)

The record for a pulsar is 716 rps. read millisecond pulsar. Dauto (talk) 02:02, 23 November 2011 (UTC)

As far as the original question goes, why would anybody expect the inside to spin faster then the outer layers? Dauto (talk) 02:05, 23 November 2011 (UTC)

Relation of molecules in mixture

Why does the result of mixture of some metrials make a mixture with new properties? Exx8 (talk) 19:17, 22 November 2011 (UTC)

I'm not sure I understand your question, but you may find some useful answers in the following articles:

• Suspension (chemistry)
• Colloid
• Solution
• Mixture

If you can restate your question or give more context, maybe someone can give you a more specific answer. --Jayron32 20:06, 22 November 2011 (UTC)

I suspect that you are using the word "mixture" in the general sense, meaning "the result of mixing any two or more things together", and not in the chemistry sense, where it specifically means a mixture where no chemical reactions have occurred between the constituents. Am I correct ? StuRat (talk) 20:29, 22 November 2011 (UTC)

Curium nuclear weapon

Given that certain isotopes of curium are fissile, would it be possible to create a nuclear weapon using curium as its fissile material? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 19:52, 22 November 2011 (UTC)

The article and section Fissile_material#Nuclear_fuel covers the additional requirements needed for a fissile material to be useful as a nuclear fuel. That would imply that fissility is not, of itself, a sufficient property for such use. Since there would therefore be some fissile materials which are not useful for nuclear fuel, those isotopes of curium may or may not be useful in that regard. I'm not familiar enough with the specific properties of those isotopes of curium, but if you are you can compare it to that information and work it out for yourself. --Jayron32 20:03, 22 November 2011 (UTC)

You might be better off asking if it would be useful in a 'practical' nuclear weapon. It would need a active cooling system and much sheilding. --Aspro (talk) 20:11, 22 November 2011 (UTC)

Why is that? It has a half-life of 8500 years - much longer than that of some other radioactive isotopes used in nuclear weapons. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 20:21, 22 November 2011 (UTC)

? Plutonium-239 has a half-life of 24,100 years. The shorter lived isotopes are considered a contaminant. A party balloon's worth of tritium gas is used in fusion devises, but that has to be replenished every 6 years or approximately, half its half life. It beta decays (and in these quantities) without much heat. The rest of the short half-life isotopes are generated after initiation – from lithium.

I don't see any reason to think you couldn't do it in theory if you could isolate relative pure amounts of certain isotopes of curium at the exclusion of some of the other isotopes. Many of the isotopes of curium have what seem to be superficially positive properties: low critical mass requirements, high neutron absorption cross sections, long half-lives. There are likely practical difficulties. It is not easy to produce in large quantities. The amount of spontaneous fission in some of the isotopes would make pre-detonation an issue (in the same way Pu-240 does for plutonium). The main practical difficulty is that curium is difficult to produce, and the processes that produce it also produce plutonium in great quantities, so why go with curium if you already had plutonium? This ignores the possibility of acquiring 10 kg of curium through some other source, though. --Mr.98 (talk) 20:39, 22 November 2011 (UTC)

(EC) Doubtless it would be possible, but it would likely also be pointlessly difficult and expensive. As the article on the element mentions, most if not all isotopes of curium can only be obtained by treating other (already-radioactive) elements inside a nuclear reactor, so amongst those elements and the reactor elements we already have material more easily and cheaply available for such a purpose. Also, the yields of the various curium isotopes so produced have (up to now) been mostly far too little to make bombs. It would be like making matches by carving each pine tree into a single matchstick (as per the cartoon we've all probably seen sometime). {The poster formerly known as 87.81.230.195} 90.197.66.65 (talk) 20:41, 22 November 2011 (UTC)

It is worth noting that as far as I can tell, curium is not a safeguarded material, unlike obviously uranium and plutonium, but also neptunium and americium, which are more obscure fissile materials. This indicates probably that nobody is too worried about it, probably for good reason. --Mr.98 (talk) 00:41, 23 November 2011 (UTC)

If one wants to look towards the impossibly exotic, then nickel-56 promises the best firework display. Get a good pair of Ray-Ban's first though!--Aspro (talk) 22:35, 22 November 2011 (UTC)

Separated, spherical plate capacitor

In my introductory physical class, which I like to call "Physics - The Science of Absolute Truth" we were asked solve this problem:

• Two separated solid spheres comprise the "plates" of a capacitor.
• They are made of the same solid, conductive material (pick one, aluminum, i.e.)
• The spheres have the same density and temperature.

• Their electrical inputs are center-fed at the inside the spheres.
• You can ignore the influence of the entry points for the feeds.

• The first sphere has radius s
• The second has radius t
• s is constrained to be >= 2t
• The centers of the "plates" (spheres) are separated by a distance > s + t but < 2s
• Call that separation u (between the sphere centers).

Calculate the capacitance.

I have no clue. Can you point me in the direction of the calculation? I got as far as the volume of each sphere, the surface area of each sphere and the charge on the sphere under various conditions. I also tried to relate the properties of a single sphere to a point charge, using the center of the sphere as the "point". But that seems to get me nowhere re: the capacitance.

My professor, Dr. Jack, refuses to help. Says it would "give it away". The net seems to provide a lot of reference material on two spheres, one inside the other, and a few on variant shapes of flat plates. Other than that, I don't seem to find anything.

As "talk" said, some of the information may be superfluous and intended to confuse. Jack is a crafty dodger.

Got this in reply to my question at the capacitance talk page:

• "Centre-fed isn't entirely clear; the capacitor can only be charged by transferring charge from one sphere to the other - along some actual path external to the spheres. While u > s + t is a necessity, s >= 2t and u < 2s seem irrelevant - likewise the density.
• "Have you seen the article bipolar coordinates? What you actually want is bispherical coordinates, but the first-mentioned article has a much clearer picture. The spherical surfaces are your equipotentials (and two of them correspond to your capacitor plates - note that these are not centred on the poles of the coordinate system). The flux paths are along the toroidal surface (which meet the spherical surfaces at right-angles). Find V(r), thence E and Vc, thence D and Q --catslash (talk) 02:22, 22 November 2011 (UTC)

To which I replied thusly:

• " ""s >= 2t and u < 2s seem irrelevant - likewise the density."" Relevant or not, they were part of the problem statement given to me.

• "The """external""" charge, so called, was imparted to the sphere at its center. For example, if it was coax, it would run inside the sphere and terminate in the center. Center-fed I guess is the best phrase I could come up with."

• "So you gave the formula for the solution, or not?" — Preceding unsigned comment added by 72.95.47.115 (talk) 10:27, 22 November 2011 (UTC)

And talk replied:

• "Not. On closer inspection, it seems that these coordinate systems do not give you an exact solution in 3D (it works in 2D - cylinders rather than spheres). Perhaps s >= 2t and u < 2s are relevant because an approximate solution is expected. Anyway take your question to the science reference desk." --catslash (talk) 15:23, 22 November 2011 (UTC)

And I:

• "Thanks! I appreciate the effort and your honesty." — Preceding unsigned comment added by 134.223.116.201 (talk) 17:28, 22 November 2011 (UTC)

I have made some minor edits and additions to my comments above, although I have not modified theirs.

Any thoughts? — Preceding unsigned comment added by 72.95.47.115 (talk) 23:19, 22 November 2011 (UTC)

From a physical understanding: Wouldn't the charges tend to concentrate on the points as far from the other sphere as possible, in coordination with minimizing the repulsion between like charges on one sphere (i.e. not all the charge would be located at the one point: there would be a gradient with lowest charge at the point nearest the other sphere and highest charge at the point farthest from the other sphere). How would a sphere then still be an equipotential surface, as would be a conductive sphere in the absence of an external field? Many capacitor problems have classic trick solutions, but this one does not ring a bell. There are lots of problems on the web for parallel plate caps, for concentric sphere caps, and for spheres isolated in space, but not so many for separated spheres of unequal radius. Are you (or anyone) able to access a ref from our Capacitance article, "Note on the Capacitance of Two Closely Separated Spheres?" It sounds like it might be right on point, if it can be extended to spheres of unequal radius. Edison (talk) 23:33, 22 November 2011 (UTC)

I guess I don't understand what the lines of force would look like on the back (distal) hemispheres of the two. The lines on the proximal side seem straightforward enough. But then you start looking at the interaction between the two hemispheres on the same sphere, and that logic seems to break down. Maybe the answer is to solve the 4 two-hemisphere problem first ( the four problems being for hemispheres of sphere 1 and sphere 2 respectively, 1-distal/2-distal, 1-proximal/2-proximal, 1-distal/2-proximal, 1-proximal/2-distal ).

Attempting a solution of the polar hemispheres does not seem helpful to this problem. It might be interesting in its own right, however.

Based on the abstract, I'd say that article is exactly what I am looking for. I'll have to find it at the library. $32 for the PDF is a little steep for a lowly student. Thanks! — Preceding unsigned comment added by 72.95.47.115 (talk) 02:21, 23 November 2011 (UTC)

aliens

DO aliens Really EXIST!? — Preceding unsigned comment added by Akshar218 (talk • contribs) 23:48, 22 November 2011 (UTC)

Probably. 109.149.81.210 (talk) 00:21, 23 November 2011 (UTC)

Yes they do. And we are they. The real problem is finding the natives. — Preceding unsigned comment added by 72.95.47.115 (talk) 02:23, 23 November 2011 (UTC)

The odds that there is intelligent life elsewhere in the universe at the moment are probably equal to 1 (100%). The odds that we will be able to communicate with them in a meaningful way are probably a lot lower (though estimating that requires estimating a lot of things we don't know much about). The odds that we will be able to visit with them and vice versa, based on current physics, before our species (or theirs) goes extinct, is probably a lot lower than that. (That's my interpretation of the Drake equation, anyway.) --Mr.98 (talk) 02:38, 23 November 2011 (UTC)

Introducing life

If humans in the future had the capability to travel to a planet near the Goldilocks zone but not exactly in the Goldilocks zone (possibly Gliese 581 g, with a pretty frigid climate) and planted microscopic plant and animal life and possibly small insects on the planet, is it possible that the life will evolve to suit the climate and environment? Could this also work for Jovian moons such as Titan and Io as well? 64.229.180.189 (talk) 03:17, 23 November 2011 (UTC)