Wikipedia:Reference desk/Archives/Science/2007 September 5

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September 5[edit]

measuring mass[edit]

Since G is known to only 4 digits (if memory serves), the mass of any planet is known to 4 digits at most. But how many digits of GM are known for Earth? For other bodies? —Tamfang 01:59, 5 September 2007 (UTC)

Interesting question. According to this, it's a ppb for the Earth, from satellite ranging data: [1]. --Reuben 02:20, 5 September 2007 (UTC)
Yeah - that is indeed an interesting question. Our Earth article quotes the mass of the earth to 5 digits - Gravitational constant quotes G to about 5 digits too - which is to be expected if we only measure the mass using gravitational experiments. There are (in principle) other ways to measure mass than through gravitation though. We were discussing the problem of measuring the moment of rotational inertia of the moon just a few days ago. That would provide an independent measure of mass that would not depend on G - but rotational inertia is a tricky thing to measure without knowing the density gradient of the body. Evidently it didn't get us anywhere in terms of a more accurate mass number. If we knew the mass of the earth (or the moon or whatever) to more precision than G - then we'd only have to measure the accelleration due to gravity ('g') to enough precision and we'd know G to more precision too. We can surely measure g to insane precision (our article Standard gravity suggests that it's been measured to at least 7 digits at sea level) and I know for sure that the radius of the earth at mean sea level at 45 latitude is known to at least 7 digits - so the precision of GM for the earth ought to be around 7 digits too - but without some other precise measure for the mass (such as using rotational inertia or something) the precision of the mass of the planet and the precision of G are intimately linked. SteveBaker 04:27, 5 September 2007 (UTC)

Science Project[edit]

I'm working on a 3d model of a plant cell. I need help finding what non-edible object I can use to represent cytoplasm, golgi body, and chloplast. Any ideas? Ex. ribsomes-small fuxxy balls —Preceding unsigned comment added by (talk) 02:04, 5 September 2007 (UTC)

On my son's plant cell model (yes, everyone gets to make one of these!) he used some 1" wide pink ribbon (stuck together with hot-glue) for the Golgi body, he put a sheet of clear overhead-projector plastic through a shredder to make long transparent strips which he crumpled up to fill up the cell as cytoplasm (you can see it's there - if you use some imagination, it looks kinda liquidy - yet you can see through it to see the other 'stuff' inside the cell) and for the golgi body we used one of those green 'Jif' limejuice containers that looks like an actual lime fruit because it's kinda round with pointy ends (you're out of luck if you don't live in the UK - I've never seen them sold anyplace else). We also used various coloured beads to represent Peroxisomes and the various vesicles. The ubiquitous pipe cleaners (which are NEVER used for cleaning pipes - but are a requirement for every single school project) were coiled up to form mitochondria and left uncurled for the cytoskeletal filaments. The nucleus was a foam ball with curled strips of paper for the endoplasmic reticulum. The cell wall was made from two clear plastic bubble containers clipped back to back with paperclips so it could be undone for the purposes of exhibition. The plasmodesmata were painted on the outside. I miss school projects - that panic 3 hours before bedtime on a Sunday night when my kid would reliably remember that the project that he'd known about for the past three weeks was due Monday. The scouring of the house for things that could *somehow* be made into a scale model of Mount Rushmore or a DNA molecule. (I once helped him build a 6' tall 2' wide DNA molecule using string, UPVC pipe, a couple of 2x4's and the entire contents of his long disused garden ball pit in under 3 hours! It turned out to be quite a structural engineering problem to keep the twist in it without the whole thing sagging - hence the 2x4's! The teacher was keen to point out that he'd said that it had to be over six INCHES tall - but four years later, and the giant DNA molecule still adorns the classroom...I guess they havn't figured out how to get it out to the dumpster yet!) SteveBaker 02:42, 5 September 2007 (UTC)

What is this creepy crawler?[edit]

I was just wondering if anyone knew what species this little creature is called. It's very fast moving because of the many legs so I was not able to catch it and toss it out the door. If it helps; the location is upstate New York.

Picture --MF14 02:07, 5 September 2007 (UTC)

Could be the House Centipede128.163.116.67 02:11, 5 September 2007 (UTC)
Oh, jeez. Now I'm more creeped out after reading that article. Thanks for the help though. --MF14 03:51, 5 September 2007 (UTC)
Could be worse ---->
--Sean 13:22, 5 September 2007 (UTC)

Remember, we look just as ugly to him. Edison 13:30, 5 September 2007 (UTC)
Yeah, when I visited the Asian tropics, I came across a few of these critters. Not many animals are "icky" to me as the tropical centipedes. I don't mind looking at a picture, but the motion that they have, and the distinct color, are disturbing. For some of them, if you touch them, will stop and coil. 19:14, 5 September 2007 (UTC)
Hey, speak for yourself! ;-) -- 14:12, 5 September 2007 (UTC)
Anyway, yeah, house centipedes. Ugly and freaky fast. Blink and you'll miss 'em. And they can get quite large. If you hit them with something (say, a shoe), they disintegrate into a mess of flimsy legs. Ugh. Something about their ridiculous number of legs and their practically unbelievable speed (for something that size, and as an insect) makes them exceptionally creepy. Bleh. -- 14:24, 5 September 2007 (UTC)
Yea, when I see one and get something to squish it with, it is usually gone by the time I'm ready, leaving me wanting to burn the house down and rebuild. StuRat 15:13, 5 September 2007 (UTC)
Just a minor quibble: centipedes are not insects. They belong to the subphylum Myriapoda that includes millipedes as well as centipedes. Although they are--like insects--arthropods, the mulitple segments and legs distinguish them from insects with their three body parts and six legs.--Eriastrum 16:45, 5 September 2007 (UTC)
Good information; thanks! --Sean 17:56, 5 September 2007 (UTC)
There's something elegant and fearsome about tropical centipedes; although they're frightening, they look cool in a Boba Fett sort of way. House centipedes are just disgusting. And are they really that poisonous? Should I, for instance, tell my cat to stop eating them?--The Fat Man Who Never Came Back 20:24, 8 September 2007 (UTC)

Its a good thing to have around actually since it is an insectivore. It will hunt and kill other insects in your home which would be bad to have. So don't kill it. Remember that it is probably killing hundreds of spiders, ants, roaches, and countless other creepy crawlies. So one creepy crawly is better then hundreds.

Heat exchangers[edit]

Why does the resistance to heat transfer (1/U) in a plate heat exchanger (with hot and cold water) decrease as the mass flow rates of each of the fluids is increased? 02:52, 5 September 2007 (UTC)

To get a start on this (homework) problem, look at the equations for conduction resistance (in the heat exchanger) and forced convection resistance in each of the fluids. A diagram showing how the resistances relate, in series or parallel, may help. anonymous6494 03:32, 5 September 2007 (UTC)

what is the capital of singapore?[edit]

-- 06:56, 5 September 2007 (UTC)

Singapore is one of the few remaining city-states. As such, the only city, Singapore, is both the capital and the name of the nation. StuRat 07:02, 5 September 2007 (UTC)
As a city-state, the capital is known as Singapore City. Rockpocket 07:04, 5 September 2007 (UTC)
I believe it's called Singapore City only when the need arises to distinguish that you are talking about the city specifically, much as New York is only called New York City when the need arises to distinguish it from the state. StuRat 07:11, 5 September 2007 (UTC)
Umm, not to be picky, but this is the Science Desk isn't it? I had to do a double check. Is this a Science Question? Anyway, it's got an answer... --jjron 07:15, 5 September 2007 (UTC)
I guess this is the closest thing we have to a Geography desk. Lots of geography questions get asked here, so....--Shantavira|feed me 08:49, 5 September 2007 (UTC)
We have a Humanities Desk which would probably be the best place for this question. Geography is one of the Humanities, but it can also be a science.DuncanHill 09:01, 5 September 2007 (UTC)
It can be quite scientific, see color. :p Capuchin 09:35, 5 September 2007 (UTC)
Okay, here's a Science question, then: how come it gets harder to read small print as you get older? —Steve Summit (talk) 13:03, 5 September 2007 (UTC)
Presbyopia --LarryMac | Talk 13:26, 5 September 2007 (UTC)
That might look like a science question, but it's actually a social thing too: the so called "web designers" these days think that the more text they can fit on your screen, the better. – b_jonas 14:10, 5 September 2007 (UTC)
Why are you whispering? Do you think we can't hear you? 14:26, 5 September 2007 (UTC)
<BLINK>What was the result? :-)</BLINK> --Anon, 22:28 UTC, September 5.
It was deafeningly quiet - I'm not doing it again, my ears hurt. SteveBaker 23:22, 5 September 2007 (UTC)
I actually did hear it in my head as a shouted whisper, or stage whisper. It was most disconcerting, and happens every time I look at it. It reminds me of reading Gulliver's Travels and finding the capitalisation and italisization (?) made me add weird emphases. Skittle 23:19, 6 September 2007 (UTC)


My father was born with brown hair and blue eyes, my mother was born with blonde hair and green eyes, I was born with brown hair and blue eyes, if I have children with a person with blonde hair and green eyes, is there a good chance that my children would be blonde haired and green eyed too? -- 07:13, 5 September 2007 (UTC)

The genetics of even fairly simple things like eye and hair colour is not as simple as your standard textbooks make out. In very simple terms brown hair tends to dominate blonde hair, so your children would more likely have the darker hair. Similarly darker eyes tend to dominate lighter ones, as for blue and green I'm not sure. So I guess the simple answer is that your kids could have blonde hair and green eyes, they're probably more likely to have something else, but basically we can't predict for sure. --jjron 07:19, 5 September 2007 (UTC)
If you want to pretend this is one of those simple text book examples, it will be 50/50. A more full pedigre of your family might offer a better picture. Someguy1221 08:13, 5 September 2007 (UTC)
To summarize without going into arcane detail: Each of your children has an even chance of blond vs brown hair. We don't know whether your hypothetical mate has two green eye genes or green+blue, though the latter is more likely; in ignorance, each child has at least an even chance of green eyes (vs blue). —Tamfang 17:21, 5 September 2007 (UTC)

Exlpoding Paste[edit]

I know that exloding paste is made using ammonia and iodine crystals, but i don't know how much of each or what concentrations to use to get more controllable blasts. Anyone have any ideas?

Nebuchandezzar 09:40, 5 September 2007 (UTC)

Here [2] are instructions. The link is provided for information only - home experimentation with explosives is highly dangerous, ill-advised, and may be illegal in some jurisdictions. DuncanHill 10:43, 5 September 2007 (UTC)
Nitrogen triiodide is too unstable to get controlable blasts. 10:45, 5 September 2007 (UTC)
"it is usually detonated by touching it with a feather but even the slightest air current or other movement can cause detonation. Nitrogen triiodide is also notable for being the only known explosive that detonates when exposed to alpha particles"
So don't try - it's not controllable87.102.5.137 10:48, 5 September 2007 (UTC)
Please do not experiment with this. It is far too unstable and unpredictable. I got little glass fragments in my hand many years ago from it going off, and some of them are still there. Fortunately my hand was between it and my face, otherwise I likely would have been blinded. "Large amounts" are anything more than more than a tiny speck. Edison 13:28, 5 September 2007 (UTC)
Luckily, iodine is not cheap. – b_jonas 14:44, 5 September 2007 (UTC)

How hot is it?[edit]

We have furnaces at work that heat the product up to ~2200° F. I'd like to know what this can be compared to. What other things, that are more common to the average person, come close to this temperature? I don't suppose we have a list of elements according to melting point or anything like that here... Or do we? Dismas|(talk) 10:59, 5 September 2007 (UTC)

This page gives the melting point of glass as 1400 to 1500 kelvin, and by google's calculation, 2200°F is 1477K. Glass says that it's melting point is "around 1000°C", so that's 1300K, which is probably close enough for your use and might be something people can compare to? "Hotter than the melting point of glass." Capuchin 11:16, 5 September 2007 (UTC)
Note 2200F = 1 204.44444 Celcius (from google calculator)
Melting points of the elements (data page)
List_of_elements_by_melting_point - better for your purposes? 11:25, 5 September 2007 (UTC)
So you should be able to melt copper, uranium (as well as silver,zinc,gold easily) but possibly not manganese87.102.5.137 11:29, 5 September 2007 (UTC)
Interesting! Thanks! Dismas|(talk) 11:41, 5 September 2007 (UTC)
May we ask what you need such a splendid furnace for? DuncanHill 13:24, 5 September 2007 (UTC)
Such a splendid furnace might be used for materials research, such as annealing, or in electronics and semiconductor dopant control (though this is pretty hot for silicon fab!). Nimur 14:29, 5 September 2007 (UTC)
Or making pots or casting Golden calfs? —Preceding unsigned comment added by (talk) 14:47, 5 September 2007 (UTC)
Actually, it is for silicon semiconductor fabrication. I handle a little over US$4 million worth of product in a single day, based on the average value of each wafer. Dismas|(talk) 20:20, 6 September 2007 (UTC)
How is the latest Opteron stepping doing? Nil Einne 14:56, 7 September 2007 (UTC)
We have great articles giving examples to things like this: see Orders of magnitude (temperature). Any power of ten with a unit like 1000 K also brings you to such a page. You have to convert 2200 °F to K first: it's 1500 K. – b_jonas 13:51, 5 September 2007 (UTC)

Headphones - left and right?[edit]

I've read the articles on both stereophonic sound, and headphones. I don't think either one tells me exactly the point of having 'left' and 'right', although I understand the point of having two channels recorded from different points of perspective. My question, does it make any difference to me whether I have the earpiece designated left in my left ear, and right in my right ear? Would there be a difference in sound if I switch them? Is there something 'wrong' in theory in terms of my appreciation of the music, if I have 'L' in my right ear and 'R' in my left? (The Ls and Rs are wearing off, and they are so small, I can't always read them w/out my glasses...) Thanks if you can help. —Preceding unsigned comment added by (talk) 13:03, 5 September 2007 (UTC)

With the headphones reversed, the stereo image would be reversed, that is to say that sounds which should be on the left would now be on the right, and vice versa. DuncanHill 13:19, 5 September 2007 (UTC)
You won't particularly notice any difference with music, however, watching a movie or playing a video game with the headphones the wrong way around will make a large difference, as the direction that sounds are coming from will be switched which can be disorienting and completely ruin the experience. With music, you're not listening to the music the way that the artist intended it (if they paid enough attention to left and right). I also find with earphones that some are moulded to fit better in the ear if you put them in the correct ears. It's not going to make much difference with plain music at all, really. Capuchin 13:22, 5 September 2007 (UTC)
More likely, you're not listening to the music the way the producer or sound technician intended it ^^ --lucid 14:06, 5 September 2007 (UTC)
I had considered making that clarification, but i'm non-productively lazy, in the sense that now I had to write this to explain myself, rather than bothering to alter it when I was initially writing. Capuchin 14:14, 5 September 2007 (UTC)
It might be a neat psychology experiment to determine if there are aesthetic or perception effects due to reversing the stereo on an otherwise un-oriented sound source. Clearly, if you are watching a movie, the visual cues will not line up - but what if there is no video feed? Will it really make absolutely no difference to the experience if the sounds are reversed? Maybe it's more enjoyable (in the statistical aggregate) to have the guitarist to the right and the bassist to the left. Nimur 14:33, 5 September 2007 (UTC)
I suppose, theoretically, there could be a right brain/left brain issue where certain sounds are more pleasing to the left ear and others to the right ear, but I don't know of any studies on this, and the music producers probably don't either. So, if they more or less randomly choose which instruments go on which sides, reversing them is just as likely to improve the music experience as it is to degrade it. StuRat 14:57, 5 September 2007 (UTC)
Generally, it doesn't matter - you just flipped the positions of the instruments and mirrored the shape of the space they were recorded in - who cares? There are cases when it matters though - when watching movies or computer games obviously someone off to the right side of the screen fires a gun - you don't want to be given the impression that they were off to your left. But even without visual cues, there are recording techniques in which microphones are placed inside the ears of a 'human analog' - a plastic model head, with realistic ears - and filled with the fluids of the correct density to simulate skull and brain, etc. These are sometimes called 'Binaural recordings' to distinguish them from normal stereophonics - and sometimes they actually use a real human head to do the recordings [3]! When you record like that, you can actually reproduce a fully three dimensional experience in which you can tell the difference between sounds coming from in front and behind, above and below as well as left and right. The human brain figures out the full spatial positioning of sounds using just two ears by recognising subtle cues to do with how the sound bounces off your skull and refracts through your brain matter! Those effects are eliminated when the sound is piped directly into your ears - and binaural recordings add that information back in from the human analog head. It's not perfect because no two people have identical heads - but it's pretty damned amazing when you hear it demonstrated. Obviously, if you wear your headphones 'backwards', you'll destroy that effect - and possibly produce disorienting weirdnesses - it doesn't simply swap back and front, left and right - it actually screws up your audio positioning senses much as if you were in a really echoey cave or something. If you go to Binaural recording you'll see that we have a sample recording that shows this 3D sound effect (you have to be wearing headphones to hear it though). However, not much stuff is recorded that way because it doesn't sound right when heard on stereo loudspeakers. There are also ways to produce similar results by processing five channel audio down to 'spatialised' or '3D' stereo using fancy computer simulations of the effect of sounds bouncing around in a typical human skull, etc - and this is done in some computer games and in high-end PC sound cards. SteveBaker 15:33, 5 September 2007 (UTC)
One occasionally hears that when you try to remember an event you look up to the left, and when you invent a lie you look up to the right (or is it the other way round?). That suggests asymmetries in perception that *could* make a difference in music appreciation. —Tamfang 17:09, 5 September 2007 (UTC)
The film Bad Boy Bubby features binaural recording. DuncanHill 00:18, 6 September 2007 (UTC)

For those of use that have enjoyed classical music for years, it could be a bit disconcerting to hear the violins coming from the left. (note: after typing that line, I reread it, and thought that I should add "no pun intended" after "disconcerting", but thought better of it) Bunthorne 04:58, 6 September 2007 (UTC)

I was about to add a comment about orchestras but you beat me to it. However... aren't violins on the left, at least for people in the audience? Pfly 07:37, 6 September 2007 (UTC)
Quite right. I blew that one. Thanks for the correction. Bunthorne 08:17, 6 September 2007 (UTC)
Hmmm - so if you are a concert musician - used to hearing the music from up on stage, you should wear your headphones backwards when you listen to concert music!?  :-) 13:11, 6 September 2007 (UTC) —Preceding unsigned comment added by SteveBaker (talkcontribs)

How flaps reduse noise[edit]

I know that flaps help increase flying time although not thoroughly but it really tough to figure out how flaps reduse noise. I am an 1st year Aeronautical engg. student and i know the base of the subject.Please answer in a detailed manner.THANK YOU —Preceding unsigned comment added by Mansnipermanoj2007 (talkcontribs) 13:49, 5 September 2007 (UTC)

I would speculate that they reduce noise by reducing turbulence, but will let an expert give a more detailed answer. StuRat 14:45, 5 September 2007 (UTC)
You are referring to flaps on aircraft wings - right? Well, when you lower the flaps you increase both lift and drag dramatically. On take-off this permits the aircraft to gain altitude much more quickly - but requiring more engine power to overcome the extra drag. This actually makes the plane noisier because the engines are on a higher throttle setting - but it als reduces the noise 'footprint' (the places where the plane can be heard from on the ground) because the aircraft gets up and out of the way sooner. In effect, a steeper climb-out concentrates the noise to a region close to the airport - reducing noise further away. Around large commercial airfields, the climb-out rate is sometimes regulated in order to keep the noise levels within acceptable levels for communities right next to the airport - or to get the aircraft up to sufficient altitude to avoid inflicting noise on communities further away. On landing, the engines are generally throttled back until the very end so the noise levels aren't so critical - I suppose the extra drag from the flaps help reduce the need for the super-noisy thrust reversers but that's a minimal kind of thing. SteveBaker 14:52, 5 September 2007 (UTC)
Jet planes almost always takeoff at maximum engine power (unless it's derating its engine to extend its life and lower maintenance, then it will go at maximum allowable power), flaps just sacrifices some acceleration for lower takeoff speed, and the overall effect is faster climbing which means it can get away from houses quicker and thus less noise for the grounds people. --antilivedT | C | G 03:33, 6 September 2007 (UTC)

physiology fluid balance[edit]

why have mens bodys got a larger average % water content compaired to women —Preceding unsigned comment added by (talk) 13:55, 5 September 2007 (UTC)

Possibly because women have a larger average % fat content, which helps during pregnancy and lactation, when extra energy is needed for the baby. This leaves room for a lower percentage of everything else, including water. StuRat 14:42, 5 September 2007 (UTC)
We've had several questions on the Reference Desk in the past that focused on the subject of "what percentage of a human is made of water." I think the consensus is that it's sort of a vague usage - i.e. which water should be counted? Pure water? Water in cells mixed with organelles? Chemically attached water? Thus, the constituency is difficult to define. I haven't heard this detail about a gender-related water constitution, but I would guess it's actually females with more water (I think I remember from biology that they have more adipose tissue, which holds water well). In any case, it's an ill-defined problem. —Preceding unsigned comment added by Nimur (talkcontribs) 14:43, 5 September 2007 (UTC)
Off the top of my head, I would assume men have a larger % water. Although adipose tissue does contain water, the cardiovascular system contains a lot more. Males have more muscle. Muscle needs more blood flow than fat. And the fact that there are more vessels means there has to be a greater volume of total blood to maintain blood pressure. So, males need more blood to fill their more numerous and larger vessels and thus contain more water.
Mrdeath5493 04:42, 6 September 2007 (UTC)

Deviation from relativistic mass for high energy particles[edit]

I understand that the 'mass' of accelerated nuclear particles deviates from the prediction of special relativity for higher kinetic energies. Can I get a plot of predicted and experimental results for this? What are the theories about this effect? 15:15, 5 September 2007 (UTC)—Preceding unsigned comment added by (talk) 15:07, 5 September 2007 (UTC)

Where did you get this impression from in the first place? That would at least help in doing a search. SteveBaker 16:47, 5 September 2007 (UTC)
Sorry, the impression is from a physics lecture I attended 30 years ago by High Energy Physicist Dr. Henry Frisch, who is still a professor at the University of Chicago. This doesn't give you much to go on. This is not about 'longitudinal' and 'transverse' mass measurement. He indicated at very high energies the measured 'mass' of particles is significantly greater than predicted by Special Realtivity's mass dialation equation. —Preceding unsigned comment added by (talk) 19:25, 5 September 2007 (UTC)
That would be Dr. David H. Frisch? ...oh...or maybe Henry J Frisch ? SteveBaker 23:05, 5 September 2007 (UTC)
I don't see anything in Frisch's work to suggest he's taking the bold step of proclaiming Einstein to be wrong - but that link to his homepage at Chicago links to a bunch of papers - many of which I cannot understand at all - so maybe someone more in tune with this stuff can speak to it. Right now, I don't see how this can be true - but the definition of mass in a relativistic universe is not a simple thing to define. See Mass in special relativity for a reasonable discussion of the confusion in terminology that's been changing over the past 70 or so years. SteveBaker 23:18, 5 September 2007 (UTC)
No such deviation has ever been seen. It's possible that Frisch was talking about new results that seemed to contradict special relativity but later turned out to be spurious, or that he was talking about some other sort of mass (such as the mass density component of the stress-energy tensor, which transforms in a different way.) -- BenRG 23:28, 5 September 2007 (UTC)
Frisch's work looks pretty conventional. Perhaps he was talking about something else? 30 years ago, physicists weren't sure of the quark model. They would be interested in cross sections, particle multiplicity, particle jets, quark confinement etc. You can find plots of cross sections here; I don't know enough to tell you if they're anomalous, though. - mako 00:54, 6 September 2007 (UTC)

Gene database question[edit]

I have an assignment, and I have absolutely no idea how to approach it. Given the names of several genes in a particular bacterial gene cluster, how would I go about finding the sequences of the equivalent genes in a different subspecies of that bacterium? If I can figure it out, I'll be using the data to design PCR primers. Cheers! - 16:11, 5 September 2007 (UTC)

I'll assume that the genes are sequenced. Well, one way to do it is to get the sequence for the relevant genes in subspecies 1 (using a database query site, such as NCBI's Microbial Genomes database), and then do a homology search to find the sequence of similar genes in another species. You can do this using the Blast tool. Flyguy649 talk contribs 17:28, 5 September 2007 (UTC)


Who do we go about seeing in regards to a non-national 'Wikipedian Board of Scientists' funded by Wikipedians? In the same sense of Einsteinian Anti-Nationalism, and yet he was funded by Americans and so he gets citizenship with the USA. I understand in science, the answer is key, but the funders of the questioning is also important, and so whatever country funds the research is the flag that those scientists go by, whether they like it or not. Can a group form a sort of United Nations portal, not with the United Nations, but a sort of Non-Nation Science Program, where the seekers of information fund the seekers of information? --i am the kwisatz haderach 16:53, 5 September 2007 (UTC)

I don't quite understand your question - but let's explain some points in the hope that we randomly hit on the right answer! Firstly, Wikipedia is largely an organisation of volunteers. We offer our time and knowledge freely and without charge - mostly for the fun of it - but also to better mankind. We are already an international group - in addition to the English language Wikipedia you are reading now, there are something like thirty different Wikipedias (of any size) for a wide range of other languages. Go to our front page - scroll all the way to the bottom - and you can read Wikipedia in German, French, Spanish...Sinugboanong Binisaya. At one time we had a version in Klingon! Funding of Wikipedia is by donations - but that doesn't pay for any of the content - it pays for the computers, the networking equipment and the staff to look after them...that kind of thing. So for the all-important content (the articles, this ref desk, etc) there is no funding and there is no nationalism. If seekers of information wish to fund us - then they can follow the link on the Wikimedia Foundation homepage where donations are gladly accepted. But those donations have nothing to do with the content of the encyclopedia - only the computers that store it and the connections out to the outside world. Personally, I suspect that most Wikipedians would object strongly to getting tied up with the United Nations - we have all of the international cooperation we need right here in our own ranks. SteveBaker 18:28, 5 September 2007 (UTC)
Well, I understand the commercial interests, publishing rights and so forth. So, I was just wondering if there was a way to totally by-pass these restrictions, for educational purposes. I know in the paper chase of edits here, not that I've added much or even subtracted, but just reading some of the removals., it seems that that's the end of topic, because in the law system or international law, both topics I have no understanding of, although I know it takes a whole heck of a long time for things to get done. I guess we'll just have to wait for the WIKI-MOONBASE. And run the servers from there to bypass the hinderances. I'll accept that there is no quick way. A Wiki-satelite with Wiki-TV channels would be interesting, but that's a whole other ballgame. --i am the kwisatz haderach 19:30, 5 September 2007 (UTC)
Commercial interests? Where? This is about the least commercial place left on the Internet! We're in the top ten most popular websites on the entire Internet - and we have not one advert! Publishing rights are very free indeed - you can even take a copy of Wikipedia and stick it up on your own website if you's one of our founding principles. Compare the articles on (for example) with those on they look familiar?! The restrictions (such as they are) on Wikipedia are mainly to prevent you doing something illegal - such as taking a photo from some other website and publishing it here (in breach of someone's copyright). The other things that get deleted are inappropriate articles. Odds are (for example) that if you write a biographical article about yourself - it'll get deleted in short order - but this isn't some "big brother" or "commercial interest" or even "publishing rights" thing - it's a group of Wikipedians who (just like you and me) come here to help maintain the encyclopedia. You can go over to WP:AfD (articles for deletion) and add your opinion to the discussion about what gets deleted and what doesn't. It's not even a matter of voting - it's done by consensus - so in order to delete an article, pretty much everyone who expresses a cogent argument for keeping it can ensure that the article is kept. Deleting articles is as much a community matter as writing them is. Heck - if you want to (I don't), then after you've had a few months of experience here you can ask to be given 'administrator privilages' so you can help with blocking spammers, maintaining order from the chaos, etc. If you can program in PHP, you can even modify the Wikipedia software! This place is much more open than you evidently think.
WikiSatellite TV would be interesting. I think it would be tough to do with our ways of working. The amount of effort it takes just to keep fresh, quality material on the front page every day demands a small army of volunteers. That would probably fill 20 minutes of TV time...where would we get the other 23 hours and 40 minutes every day? TV is voracious - it's expensive (Wikipedia runs on about $1,000,000 per year - TV stations eat that much in a couple of days!) - and it's not suited to what we do. We are continually tweaking and fixing articles - my front-page article on the Mini has undergone literally hundreds of edits since it was deemed 'an example of our very best work' a year ago. Nothing here is ever truly finished. SteveBaker 19:55, 5 September 2007 (UTC)
WOW! Thanks, that's a lot of THE KNOW. Yeah, I'm pretty new at this, and I'm just wondering if that 100 year thing on the Publishing of literary works, namely the deletion of the 70year rule here [on Suicide Notes]. But then that made me wonder about old TV, Radio, and Film, and Music. The articles are great on all the arts, but to actually have access to the old programs and music catalogs would be great. That's what I meant on commercial. I wasn't very clear earlier, sorry. And thanks for all this Great info. --i am the kwisatz haderach 21:24, 5 September 2007 (UTC)
As things come out of copyright, they DO get added into Wikipedia - we're more than happy to take it too! A large fraction of our early content (tens of thousands of articles) came directly from an out-of-copyright version of Encyclopedia Britannica! If you hit 'random article' enough times you'll eventually hit an article with a template box in it that says that the text of the article came from there. Lots of articles are illustrated with pictures from out-of-copyright books. We also make good use things like NASA photographs that have free license terms because they were made by a branch of the US government. There are all sorts of sources of free images, music and text that we actively seek out. But we can't break the law - and that means we have to be exceedingly careful about use of materials that are still under copyright. But don't worry - if it's legal and free and if it's true and relevent - we'll use it. SteveBaker 22:00, 5 September 2007 (UTC)

Schrodinger Equation[edit]

So there we are, the Schrodinger equation.My question is this, having had no education in any quantum mechanics, or knowledge of how to acquire one (relatively quickly) short of reading various freely available science books, I want to know how to derive psi using this equation. As it seems the books only deal with concepts, and talk of equations, their meanings, and their history, but not how to use them. So I'll start with some simple examples.

Can you please help me derive a wave function for psi in the following examples. I have no clue where to start, all I know is a basic anatomy of the equation which consists of the names of the operators, and their meanings and implications, but not how to use them, so I have no idea where to start.

  1. A Particle in a 1 dimensional space (x) of known location (x=0)
  2. A particle in 3 dimensional space (x,y,z) of known location (0,0,0)

If these examples are in fact horrifically complicated, you can simplify them. But At least justify it.

Thanks for your help.

ΦΙΛ Κ 17:02, 5 September 2007 (UTC)

You can't have a particle of "known location." If a particle has a known location, it is not a wave. If it were a wave, that wave would simply be a Dirac delta wave, and there wouldn't really be anything interesting about it except that applying the momentum operator would yield infinite variance. But the first thing to do when attempting to determine the wave function of a particle, you must define what restrictions you place on that particle. The "boundary conditions." Typical boundary conditions are things like, (if the space the particle exists in is infinite) the particle must have zero probability of existing at infinity, (if the space the particle exists in has boundaries that require infinite energy to cross) the particle must have zero probability of existing within or beyond the boundaries. This is all you really need for solving the relatively simple things like particle in a box problems, in any number of dimensions. Things won't get horrendous until you start imagining more complex situations, perhaps with multiple interacting particles. Other hallmark problems are quantum harmonic oscilators (a quantum pendulum), "particle in a bowl." Now, I don't have my notes or text books here on my vacation, so I can't provide any details on actual derivation. But the link I provided for particle-in-a-box does include derivations for up to 3D. Someguy1221 18:21, 5 September 2007 (UTC)
The known location thing wasn't the result of blatant misunderstanding of wave functions, more so of the equation. What I meant was to start with at a given time it is at this location. I don't know if psi describes how the equation propagates with time (which I sort of assumed) , which if it does, knowing a particles former location still allows it to have a wavefunction. Which is what I meant. ΦΙΛ Κ 18:42, 5 September 2007 (UTC)
Well, in that case it can be specified as known location at known time, your initial condition. Someguy1221 18:46, 5 September 2007 (UTC)
I was more lookin to calculate a wavefunction that varies with t. ΦΙΛ Κ 20:45, 5 September 2007 (UTC)
Generally you find time-varying solutions by expressing the initial state as a superposition of time-invariant solutions (energy eigenstates). If your state at is , where has energy for every , then the state at any later time is easy to find: it's . (By the way, the equation you wrote down isn't the most general form of Schroedinger's equation; it's a special case for a single nonrelativistic point particle with no internal degrees of freedom, like spin.) -- BenRG 23:53, 5 September 2007 (UTC)
You need to specify the potential, V(x); that defines the problem. You can have a constant potential, a square well for a "particle in a box," a simple harmonic oscillator potential, various kinds of delta-function barriers and wells, ... If you work in 1-d and set V(x)=0, then you have a free particle with any momentum you want and a simple set of energy eigenstates. If you start the particle off in a well-known position by making psi(x,t=0) a very narrow gaussian function, it will spread out as a Gaussian with larger and larger width. --Reuben 23:34, 5 September 2007 (UTC)
Will a Dirac delta also evolve into a Gaussian? My intuition says yes, but I can't prove it. —Keenan Pepper 00:26, 6 September 2007 (UTC)
mmh gaussian = e-ax^2, using fn(x)= e-x^2n then n=1 gaussian like, and n=infinity gives dirac delta?)my mistake87.102.6.138 11:45, 9 September 2007 (UTC)
Probably best to ask on the maths desk... 17:54, 6 September 2007 (UTC)
You seem to be asking is a gaussian extrapolated to zero width the dirac delta - good question (smile - maths desk I think) 18:10, 6 September 2007 (UTC)
"Yes," but in a dum-dum sort of way. You can take a Dirac delta to be the limit of narrower and narrower Gaussians, and those all stay Gaussian as they evolve; so does the Dirac delta function, in form. But when you ask how fast it spreads out, you find that it spreads out infinitely fast! An infinitesimal instant after t=0, your nicely localized particle has become evenly spread out through the entire universe. It's as likely to be on Tralfamadore as still somewhere in the lab. You can understand this because the initial delta function has every possible momentum equally represented, even ridiculously large values. So after a tiny tiny tiny passage of time, the particle is almost certainly totally gone, and to have gone an arbitrarily large distance away. This is the prediction of the Schrodinger equation for the evolution of a Dirac delta function state with V=0. Of course, it's not physically meaningful. A Dirac delta function is not technically a good wave vector, for one thing. For another, the Schrodinger equation is not relativistically correct, and this solution blatantly violates causality. --Reuben 20:32, 7 September 2007 (UTC)
But a gaussian could not be a solution to the shroedinger equation (try it), especially when V(x)= 11:49, 9 September 2007 (UTC)

IGNORE - found the answer (((I'd like to see somebody explain the derivation of that equation - specifically why the analogy to the second differential of a moving wave is considered to be good for everything else. Anyone recognise what I'm talking about and able to answer? (please?) 09:07, 6 September 2007 (UTC) )))

The original questioner may want to learn some general techniques for solving boundary value problems and differential equations, since these skills are essential to the mathematics at hand. Nimur 18:15, 6 September 2007 (UTC)



Please don't type in all CAPS, it is equivalent to shouting. The Solar Power article has the information you need, specifically in the section entitled "photovoltaics." --LarryMac | Talk 18:40, 5 September 2007 (UTC)

on angle-iron stands on a flat surface such as the ground or the garage roof. A clever person in some latitudes could build a house with the roof angle equal to the latitude (flatter near the equator, steeper nearer the poles, problematic as you get very near the poles) for maximum annual efficiency. I would certainly use a rack of storage batteries (about 55 lead acid cells would total 110 volts), but if you are willing to lose power when the utility goes dead you could save a lot of money by skipping the battery storage. Other battery types require other voltages per cell. I would probably buy some 110 V DC lights (Incandescent light bulbs work well on DC, special compact fluorescents are needed) and motors and and replace the AC motors on various appliances, since DC motors work fine and there is not the need for invertor and battery capacity. I would use a solid state inverter which efficiently produced something closely approaching a sine wave, rather than a square wave (which is cheaper and easier). I would try to sell excess power back to the utility. Just powering some of your load by a separate sopar power circuit will lower your monthly bill, but in some places the meter can actually be made to run backward. In others, there is a separate meter for the power you generate. If you like retro things, and don't mind some noise and loss of efficiency, you could use a 110V DC motor to drive an alternator to produce the frequency or frequencies and voltage or voltages you desire to operate your equipment. Edison 21:43, 5 September 2007 (UTC)

What's up with the ElectroMagnetic Frequency, Kenneth?[edit]

[rTMS] / Ipod / Cellular RF / Radio Transmissions / Blood / Iron are the relevant topics to questioning. ElectroMagnitism. [Diagram]

I read up on Transcranial Magnitism, as well as the many researches done on Cellular RF levels. Oh the joys. Basically my questioning is in the levels of Iron found in the bloodsystem and would these of a higher?lower? content effect normal? brainfunctioning? Also throwing in the Ipod factor. I know the headphones are magnatized, just holding the stock white headphones together, they magnetically connect. Also charging my Ipod in my car, once I plugged it in the lighter socket, I noticed some of the further radio frequencies that I get in Los Angeles from San Diego became distorted, so I would assume that my Ipod is picking up/absorbing some sort of frequency. I know the Ultrasonic sounds effect dogs as well as fleas and deer., so this may also fall into the biology of our species. So, basically my question is in regards to Magnatism in the Bloodsystem, and the rapid changing of frequencies?? I'm no scientific man, but I am a Layman american that wonders the streets from time to time. --i am the kwisatz haderach 17:40, 5 September 2007 (UTC)

So many questions!
  • Don't worry about Transcranial Magnetism...there are a lot of people on the internet who talk complete nonsense about magnets - mostly because (a) they seem mysterious and have a strange intellectual 'pull' for cranks and scam artists...and (b) they can sell you stuff like magnetic bracelets and magnetic inserts for your shoes that have absolutely ZERO effect on you. Think about this - people go through CAT scanners every day - thousands of people every day. The magnetic field from a CAT scanner is enough to pull a metal object from a table 5 feet away and to hit the machine with enough force to leave a dent. Yet not one single side-effect of those amazingly intense magnetic fields has ever been detected. Do you seriously think a pair of wimpy iPod headphone magnets will have an effect? No - humans are pretty much totally insensitive to even huge magnetic fields.
...not one single side-effect... Not so. Transcranial magnetic stimulation is widely accepted as a real phenomenon. Agree with your other points, though. —Keenan Pepper 21:16, 5 September 2007 (UTC)
  • Ultrasound's not electromagnetic. Electromagnetic radiation is radio, radar, light, infrared, ultraviolet, X-rays, etc. Sound is air pressure - a totally unrelated phenomena. Ultrasound is also generally unimportant to humans - it's called ultrasound because it's too high in frequency for us to hear - and (lets face it) we use it to scan a pregnant woman so we can get pictures of the baby - it's fairly safe to assume that this isn't terribly dangerous!
  • Your iPod may well have affected your radio if it was poorly shielded or the radio had a bad ground wire or something. A radio receiver is very, very sensitive to electromagnetic waves - it has to be in order to pick up a signal of a few tens of watts (like less than a lightbulb) at distances of several miles. Hence the slightest amount of leakage from the computer in the iPod (which operates at the same kinds of frequencies that radio signals run at) can be picked up by the radio as interference.
  • Forget about magnetism's effect on the bloodstream - there isn't one.
SteveBaker 18:16, 5 September 2007 (UTC)
  • I agree with the above, but am noting that CAT scans use X-rays, while MRIs use magnets. --Sean 18:42, 5 September 2007 (UTC)
Oops! Sorry! (My wife would be horrified - she used to use those machines!) SteveBaker 19:03, 5 September 2007 (UTC)
See also Electromagnetic spectrum. -- SGBailey 19:28, 5 September 2007 (UTC)
I recall being injected with Nickel for a CT scan (regarding possible epilipsy, not diagnosed), nurse said something about it'll show up on the x-ray. But I think that was just for viewing rather than any side effects on thinking. I'm not sure, but they may have a magnet on that machine?? EEG is when they patch you up with all those sticky tabs and wires. --i am the kwisatz haderach 23:47, 5 September 2007 (UTC)

Names of Sun and Moon[edit]

Why is it that we dont have an official name for our sun and our moon when weve seen that theres hundreds out there? We call it "the sun" and "the moon" as if it's the only one. I asked my chemistry teacher and she said she didnt have an answer for me. I'd prefer calling our sun Sol, and our moon, Luna. PitchBlack 20:47, 5 September 2007 (UTC)

I imagine it's because the sun and moon have always been there during the development of human languages. Although we now know of other moons in the solar system and that the sun is a star, these discoveries are relatively recent. Note that Sol and Luna are Latin words which mean sun and moon. -- Flyguy649 talk contribs 21:09, 5 September 2007 (UTC)

Note that in writing you can say "the Sun" and "the Moon" to make it clear that you mean the ones pertaining to the Earth (which can also be capitalized to distinguish it from earth meaning dirt). Not everyone follows this convention (but everyone should). --Trovatore 21:13, 5 September 2007 (UTC)

I thought our solar system was called "sol"... or have I invented that myself...? SGGH speak! 21:23, 5 September 2007 (UTC)
It's pretty clear that 'Sol' and 'Luna' may be used when there is any ambiguity - and most people will know what you are saying. But until a large fraction of humanity lives where there is some possibility of confusion, I think we'll still be (informally) saying 'sun' and 'moon'. When a bunch of us live on a planet orbiting Alpha Centauri, (or wherever) - I doubt we'll be talking about "Alpha Centauri-rise" and "Alpha Centauri-set" - we'll still talk about sunrise and sunset and "the sun" will gradually come to mean "the local star of whatever planet you happen to be on". When we talk about the old days on Earth, we'll probably talk about the differences between "our sun" and Sol. Ditto for moons. But we don't know that for sure - and we won't know how people will talk until it happens - because language evolves in strange ways. Meanwhile, our language is perfectly well adapted to knowing when people are talking about 'the moon' (meaning Luna) versus talking about 'Charon, the moon of Pluto' - so we can carry on using the old language until something forces us to change. SteveBaker 21:52, 5 September 2007 (UTC)
Terra is also used to refer to the planet Earth, but usually only in a scifi sort of sense. --Mdwyer 21:56, 5 September 2007 (UTC)
The problem doesn't seem to have arisen in the case of the Earth. We don't talk much about other earth's - we talk about other planets - and for some reason, we don't often call this place "The Planet" (except maybe as in "Save the planet"). But 'Earth' is here - and I don't think people living on mars will ever call it anything other than "Mars" - so I doubt much confusion will arise. The worst case confusion might be when we talk of the soil as "earth" when (on Mars) we should be calling it "regolith" - but I suspect that we already have enough other words (such as "dirt", "soil", etc) to avoid that potential problem. As someone pointed out the last time we had this discussion (yes, it's FAQ) - the word "Terra" probably came about from SciFi because there is no nice word for the people who live here. "Earthlings" sounds too much like "weaklings" to work in many contexts - "Earthicans" is just nasty - but "Terrans" works quite well - and we already use words like 'terrestrial' in contrast to 'lunar' or 'solar'. But as with all things linguistic - only time will tell whether a word will 'stick'. SteveBaker 23:01, 5 September 2007 (UTC)
For the same reason that we can often say "the door" or "the street" and expect to be understood, though we each have direct experience with many doors and many streets. —Tamfang 22:00, 5 September 2007 (UTC)
As far as I know, we do have "official" names for all three bodies: Terra, Luna, and Sol. It's just that (for the reasons discussed already), we don't end up using the official names that often. But this isn't a unique occurrence, either: I mean, how often do we call Queen Elizabeth "Elizabeth Alexandra Mary Mountbatten Windsor"? --Steve Summit (talk) 23:45, 5 September 2007 (UTC) (And, yeah, I know, that's not quite her official full name, either.)
I doubt that these names are "official" in any real sense. -- JackofOz 23:50, 5 September 2007 (UTC)
I think Steve has been misled by science fiction, which does sometimes use those Latin names that way. Side comment: when I read my first astronomy books, it seemed clear to me that what they were saying was that using "moon" to refer to anything but the Moon was babytalk: Ganymede or Phobos is a "satellite", not a "moon". I find still find it jarring to see the generalized use of "moon" so widely accepted now. --Anonymous, 02:30 UTC, September 6, 2007.
Using "sun" to refer to anything but the Sun is babytalk as well: "star" is much better. A.Z. 06:43, 6 September 2007 (UTC)
I disagree with both of the above. The term "moon of (e.g.) Jupiter" is well established; there's nothing babyish about it. I think there's a nuance between "moon" and "satellite" -- a "satellite of Jupiter" is any bit of detritus that at the current moment happens to be rattling around that enormous gravity well, but might plunge into the clouds next week. A "moon of Jupiter" is something you expect to be larger, rockier (not a chunk of ice nor a probe from Earth), and have a more circular orbit with a perizene far enough from the cloudtops and from other Jovian moons to be stable for a while.
The issue is different with "sun"; the use of "sun" as a common noun meaning "star" is poetical. But again it's not babytalk; it's supposed to be evocative. --Trovatore 07:23, 6 September 2007 (UTC)
For whatever it's worth, the first astronomical use of the word satellite was Galileo's application of it to Jupiter's four conspicuous courtiers. —Tamfang 20:51, 6 September 2007 (UTC)
A better reason, perhaps, to object to "moon" for satellites of other bodies is that Earth's Moon is not a satellite of Earth, i.e. it is outside Earth's gravitic domain: the Sun exerts more than twice as much gravity on it as Earth does. So far as I know, it is unique in that. —Tamfang (talk) 18:38, 17 March 2008 (UTC)
The name of our sun is Ra as any Egyptian will tell you —Preceding unsigned comment added by (talk) 01:04, 6 September 2007 (UTC)

The original question is flawed. "Why is it that we dont have an official name for our sun and our moon when weve seen that theres hundreds out there?" "The Sun" is the official name for the sun - the others are all stars (as is our sun), and by analogy we sometimes refer to them as suns. Similarly, the official name for the moon is "The Moon" - the others are all natural satellites, and by analogy we sometimes (frequently) refer to them as moons. An analogy might be if you asked why the ancient coin, the Cash, had no official name, since you use cash to buy things in lots of different countries. Grutness...wha? 01:58, 6 September 2007 (UTC)

I still quibble with this notion of "officialness". "The Sun" is the official name of the Sun in the same way that "bread" is the official name of bread, and "water" is the official name of water. There's nothing official about any of these names. We're talking about common, standard, normal names for things that have been known to humanity since time immemorial using only their senses, and in whatever language they use. When it comes to things you need a telescope or a microscope to detect, science comes up with a new name for a newly-discovered object, and that's where a level of "officialness" comes into play. But even there, names still differ from language to language. -- JackofOz 05:53, 6 September 2007 (UTC)


No need to shout. I agree with everything you say, with the exception of the word "official". -- JackofOz 09:32, 6 September 2007 (UTC)
Sorry, I just wanted to be heard. 10:24, 6 September 2007 (UTC)

"we call the sun the sun .... as if it's the only one" - yes that's correct. 09:02, 6 September 2007 (UTC)

I don't think you are seeing the 'big picture' here. The most significant problem is with 'the moon'. We use the term 'moon' to mean any body that orbits a planet - not just the one that happens to be orbiting our planet - you can argue that this was a poor choice of language - but that's how it is. This ambiguous language only works because when you say "Oh - look up at the moon", people know from the context that you are likely to be talking about the one that's handily nearby - Earth's moon. But if you were standing on the surface of Mars and Phobos was just rising - you'd probably say "Oh - look up at the moon" and nobody would be looking for the Earth and it's moon - they'd be looking for Phobos. So, if you buy that argument, there is a problem. If you are standing on Mars and you actually DO want people to look at Earth's moon - you need a name for it because 'the moon' would refer to Phobos (or perhaps Diemos). The generally accepted name is "Luna". If we ever make it out to stand on a planet orbiting another star, we may well have the same problem with people calling that star "the sun" - so we need a word like "Sol" to mean our sun, as opposed to the local star. This is not unusual. If you are in a house that contains three tables - a kitchen table, a coffee table and a dining table - but the room you are in contains just one of them then you are likely to say things like "Put it down on the table" - without going to the trouble of saying which table. But if you are away from home phoning your wife and telling her where you left her car keys, it's no use saying "They're on the table" because her very next words will be "Which table?" - you're going to say "They're on the coffee table" to make that clear. That's the same situation we're in right now - because we are not yet spacefaring people, we can sloppily refer to "The moon" and the meaning is clear...but in the future, we'll need an actual name for our moon - and it seems that "Luna" is that name. But as I said earlier, until humans start to do that kind of thing, we don't know how the English language will evolve to account for that. SteveBaker 13:06, 6 September 2007 (UTC)
Is it not possible that in the future people living on for example a planet round Sirius will call the light in the sky "Sirius", and if any moons are present will call it the moon or just make a new name for it. They may be able to point out the sun and say "that's the sun, where our ancestors came from." 17:29, 6 September 2007 (UTC)
It's obviously impossible to predict the future - but Sirius is a nice simple name. Suppose it's "Alpha Centauri"? Also, we have a bazillion words like sunrise, sunset, sunblock, sunglasses, sunroof, sunshade, sunlight, suntan, etc. Are you really going to be wearing 'siriusglasses'? How about 'alphacentauriglasses'? If we do come to live on a star with a nice compact name, then I suppose it's possible - but I think it would be hard to get out of the habit of saying "Oh what a beautiful sunset". The word 'siriusset' somehow doesn't do it! So I think we'll look back at "Sol", "Luna" and "Earth" and call whichever star/moon we happen to be closest to "the sun" and "the moon"...but as I said before - there is no way to know for sure. SteveBaker 21:54, 6 September 2007 (UTC)
I don't agree at all that it's sloppy to refer to our moon as "the Moon". That usage long predated humanity's awareness that some other celestial objects also have natural satellites. If anything was sloppy - and I don't agree that it was - it was the use of the word "moon" to refer to a natural satellite of any planet. We talk about Jupiter having 16 (or whatever) "moons". But they've all been given their own unique names, so where's the problem? Your scenario about standing on Mars and wanting someone to look at Earth's Moon as distinct from Phobos is one of the best examples I've seen of ... well, super-contrivance, if you'll forgive me. We'll need to solve a hell of a lot of much harder problems than this naming issue before we ever get to actualise that scenario. As for "Luna", that is indeed one name that has been used for our Moon; a name that astronomers seem to like, but it has nothing like the official status that Pluto now has as a dwarf planet (and astronomers don't have a monopoly on the Moon anyway). Another is Selene, which gives rise to words such as selenium, selenic, selenotropism [4] and selenotropic, and selenographer - see here for a fuller list of such words. The study of the Moon is selenology, not "lunology", but the words "lunar", "lunatic" and "loon" come to mind. There are also Artemis, Diana, Phoebe, Cynthia and Hecate. -- JackofOz 05:40, 7 September 2007 (UTC)
You're right - but the relative lack of words that begin with 'lune'/'luna' is an advantage - those are words that would have to change because they wouldn't fit if we lived on Mars. As for the words that begin with 'seleni'/'seleno' - those are CERTAINLY not problematic because they are all so very obscure. But when you look at all the words that begin with 'sun' - all in very common usage - that's going to be a problem if we were to choose to use 'Sun' to mean 'The star nearest to Earth' rather than 'Whichever star is nearest to the planet you are living on'. I said three times before...we don't get to choose what things are called. Names evolve, language changes. We won't know what something will be called in the future. Right now, there is little (if any) ambiguity. SteveBaker 13:45, 7 September 2007 (UTC)

In hindsight "the" was attached to the Sun and the Moon. You are assuming that the ancients who first named the two brightest objects in our sky as "Sun" and "Moon," knew that the universe( if they could have conceived of a thing) consisted of countless other solar systems many with planets and their own moons. If they were to think them unique, then what they called them would be their proper names or titles. Only millenia later could we realize that suns and stars where essentially the same thing, and "a" be applied to the Sun and the Moon.


is there any vitamin out there that increases penis size? like calcium, one of the b's ... it just kinda stuck me as puzzling... 20:49, 5 September 2007 (UTC)

No. See Penis enlargement#Pills. —Keenan Pepper 20:58, 5 September 2007 (UTC)
  • If you're young and still growing, good nutrition -- including adequate vitamins -- will indeed increase the size of your penis, along with everything else. You'll probably get plenty from your food, though. If you're old enough that you're not growing anymore, then the size of your penis is the probably the last thing you need to worry about. --Sean 21:23, 5 September 2007 (UTC)

just what the Reference Desk needs, good old wholesome Vitamin P-ness. —Preceding unsigned comment added by (talk) 21:53, 5 September 2007 (UTC)

Wow, jeez reading this has me puzzled too now... now that I think about it- that's a really good question, I doubt that there has been sufficient research done yet though.

Can you keep a Kea as a pet?[edit]

Can you keep a Kea as a pet? I've seen them on TV and read a lot about them recently and I wouldn't mind adding one to my parrot menagerie, if there's any breeders in England. Anyone know? Thanks. -- 22:40, 5 September 2007 (UTC)

According to this article [5] there is currently a 15 year ban of keeping them in captivity so the chances are you won't be able to have one legally. Exxolon 23:44, 5 September 2007 (UTC)
But that's presumably in New Zealand. The original poster appears to be in England. --Anonymous, 02:37 UTC, September 6, 2007.
I actually did once see a captive-bred, tame pet Kea listed in the classified ads section of the bird paper I sometimes get (yes, I'm in England). It was priced at over £1000 ten or so years ago, so expect to pay more now, if you can find a breeder. --Kurt Shaped Box 07:57, 6 September 2007 (UTC)
They are notoriously destructive. Probably don't make ideal pets.--Shantavira|feed me 10:52, 6 September 2007 (UTC)
They are notoriously destructive and also both notoriously intelligent and mischievous. Keeping one as a pet would be very difficult, to say the least - I'm not kidding when I say that one could probably work out how to pick the lock of any cage it was in within a couple of hours. Because of their intelligence and curiosity they also get bored very easily, so mental stimulation of some form would be essential - even more so than most other parrots. As for the legality of it, there are very strict laws about getting native birds out of this country (I'm in NZ), so getting a Kea would be very difficult in the first place. I must admit that they're very impressive in the wild, though - and nonchalant around humans to the point of arrogance. There's a winding stretch of road north of Te Anau in southwest NZ where cars have to slow down to a crawl. Keas in the area know that tourists often stop to feed them (even though it's discouraged by Dept. of Conservation staff), so they sometimes force cars to stop by landing on car bonnets - directly in the driver's line of sight - while cars are still moving. Grutness...wha? 12:32, 6 September 2007 (UTC)
Found some pet/captive bred baby Kea videos on Youtube ([6], [7], [8], [9]). They do seem to be rather energetic birds. --Kurt Shaped Box 15:55, 6 September 2007 (UTC)
If you are going to keep them as pets, please at least make sure everything is above board so to speak Nil Einne 19:20, 6 September 2007 (UTC)

Bacteria that form structures?[edit]

Are there any forms of bacteria or other single celled organisms that produce structures through the movement of chemicals through their cell membranes? I think that in the more cellular differentiated organisms, such as us, this occurs in the form tissues in the body. (coligen??) I am wondering if there is some intermediary stage where individual cells work together to modify their environment?

Any insights would be appreciated,

Ebenbayer 22:41, 5 September 2007 (UTC)

Diatoms. Not bacteria, but single-celled, and they form intricate structures. --Reuben 22:50, 5 September 2007 (UTC)
Dictyostelid comes to mind - but there are all sorts of Slime moulds that do this kind of thing. SteveBaker 22:52, 5 September 2007 (UTC)
Stromatolites were formed by cyanobacteria. Does this count? -Arch dude 23:07, 5 September 2007 (UTC)
Stromatolites form 'piles' of cells - and Diatoms make large fixed-shape structures - but Dictyostelids actually communicate with each other and form things that look and operate just like multicellular plants for some of their life-cycles - but then they can split back into individual amoeba-like cells - then re-form as a thing that can move around like a slug. They look and behave like unicellular animals, multicellular animals and plants at different points in their lives! Very, very wierd critters. SteveBaker 02:09, 6 September 2007 (UTC)
Caulerpa prolifera.JPG
The Caulerpa seaweed at right is a single-celled organism. Also, flagella are like little chemical propellors. --Sean 13:16, 6 September 2007 (UTC)

Scientific Method[edit]

Who was the first person to use the scientific method? —Preceding unsigned comment added by (talk) 23:29, 5 September 2007 (UTC)

Take a look at History of scientific method, but I doubt there's a definitive answer. Exxolon 23:40, 5 September 2007 (UTC)
There isn't a definitive answer, in part because there isn't one set "scientific method". -- 13:47, 6 September 2007 (UTC)

Naked Ear[edit]

Can the Naked Ear(I've heard Naked Eye never Naked Ear as a term) hear radio frequency? Or Ultrasonic waves? Lets say your standing close to Electric Grid System, not the mechanical functions of the transformer box, but rather the actual electric field? Or is ringing of the ears just a loss-of-hearing symptom? Thanks. --i am the kwisatz haderach 23:52, 5 September 2007 (UTC)

  • Nope. Can't hear stuff out of the range described in Hearing (sense). As for ringing, it could be a lot of's not medical advice to direct you to the article on tinnitus, is it? — Scientizzle 00:05, 6 September 2007 (UTC)
    • Also, it would not be possible to hear a radio frequency for the simple fact that radio waves ain't gonna move your ear drum. and ultrasound is, by definition "a cyclic sound pressure with a frequency greater than the upper limit of human hearing". — Scientizzle 00:05, 6 September 2007 (UTC)
      • actually, you could be able to hear it, your brain just wouldn't know what the heck to make of it. 03:18, 6 September 2007 (UTC)
        • How could you be able to hear it? How would the radio waves cause your ear drum to vibrate? —Keenan Pepper 03:54, 6 September 2007 (UTC)
By electromagnetic induction. (it's a possibilty if the ear canal cilla are electrically conductive - which they will be if they are wet..) I'm not saying this is what happens - just suggesting this as a possibility.. 09:26, 6 September 2007 (UTC)
        • Exactly. An ultrasonic frequency will make an ear drum vibrate, but the "hearing" comes from the nervous system's ability to accept, propagate and interpret said signal. Only mechanical energy can vibrate the ear drum, eliminating EM waves (such as radio frequencies) as a possible source of sound. — Scientizzle 04:05, 6 September 2007 (UTC)
So what we're really saying is that a person's body is impacted by ultrasound waves, because otherwise it wouldn't be possible to make ultrasound images, but the impact is imperceptible by the person. In particular, the aural mechanisms are not equipped to translate the signals into anything resembling sound. As far as the ear is concerned, there simply is no sound, and hence there is no hearing. -- JackofOz 05:40, 6 September 2007 (UTC)
See Cochlea and links from there for nitty-gritty details on how sound is turned into signals in the brain, or not turned into.. as the case may be. A vibrating eardrum isn't enough. The Organ of Corti is a fairly amazing structure that essentially analyzes sound by frequency, within certain limits. Pfly 06:59, 6 September 2007 (UTC)

If you have high powered pulsed ultrasonic or radio waves (such as radar), it is possible to hear something as the rapid heating effect makes a click that can be heard. This sort of power level however would not be safe. So plesae don't try standing in front of a radar. Graeme Bartlett 22:53, 6 September 2007 (UTC)

The OP reminded me of something I haven't thought about in years, but experience on a daily basis. What is that sound that a television makes that is audible even when the volume is turned all the way down? The volume can be all the way down, with me 20 meters away, and I can still tell whether or not the television is on. It isn't quite a "ringing" in the ears. The only way I know to describe it is as a very high pitched whine, almost inaudible. I've noticed that computer monitors have a similar but softer sound. Any ideas? 04:02, 9 September 2007 (UTC)
Are you thinking of the noise of a Cathode Ray Tube? It's a high-pitched whine, and it tends to be heard by the same people who can hear 'The Mosquito'. Skittle 17:01, 9 September 2007 (UTC)
You are probably hearing the high-voltage power supply, which takes the standard household voltage (115V AC 60Hz where I live; both frequency and voltage vary by region) and converts that to 25KV or higher DC. This high voltage is needed to convince the electrons in the back of the tube that they should leave the "gun" and accelerate towards the front. The resulting stream of electrons can be steered by magnetic fields, and draw a picture on the front face of the tube. I'm sure there's an article giving more details.
Anyway, the HVPS uses a transformer with only one or two loops on the primary winding, but thousands of loops in the secondary winding, driving a humongous diode. Not much current generated, but not much is needed; you are just generating a voltage difference inside a vacuum tube. When I worked as a TV repairman back in the '70s, that sound you hear was either a low buzz, meaning that the primary was beginning to vibrate in the magnetic field and should be replaced - it really WAS just a couple loops of wire, easy to replace, or a high painful whine that meant the secondary was going to fail soon. "Soon" being relative, of course. Maybe tomorrow, maybe in ten years. Cats and dogs hate it.
Important safety tip: Playing with the HVPS leads to death. Don't do it. Don't ever even stick your hands in the back of anything with a CRT, until the HVPS has been shorted out. The universe doesn't care how nice you are; only how stupid you are. 14:31, 11 September 2007 (UTC)
That's probably what I'm hearing, but I'm forty and can still hear it, even after years of firing weapons while wearing only one earplug. Hehe, I never knew about The Mosquito. LOL, what a concept. 23:44, 9 September 2007 (UTC)
idk what any of this means! lol!!!