Wikipedia:Reference desk/Science

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August 28

paranchute for jumping off building?

If somebody needed to jump from the 24th floor of a building (this building has no 13th floor) in an emergency, what type of parachute or other available technology should they use to ensure the safest landing on the pavement below?--Sonjaaa 01:31, 28 August 2006 (UTC)

How about a parafoil? I think 22 floors is enough to inflate the parachute. And you need to have lots of control over the chute, in order to not crash into the building or land on the road. --Bowlhover 02:48, 28 August 2006 (UTC)

You might want to do more research before trying it though. HighInBC 03:43, 28 August 2006 (UTC)

You need one that opens especially quickly. There's something about this at BASE jumping.--Shantavira 07:21, 28 August 2006 (UTC)

I believe there's a collapsible tube that can be placed in a window, then the people drop inside the tube. It's elastic, so friction between the tube and person slows their descent. You need a clear path below the window to use it, and only one person can be in the rescue tube at a time. Still, hundreds could potentially be rescued using each tube. StuRat 08:46, 28 August 2006 (UTC)

Yeah, but wouldnt your trousers get hot and ignite before you had dropped more than a few floors?--Light current 22:22, 28 August 2006 (UTC)

A parachute would be a bad idea because it needs to open. Instead use something that is already open, like a hang glider. Also a bit handier to carry around than a 70 m long tube. :) Of course, if the 13th floor is missing, the building would instantly collapse, so having something like that handy would be very handy. Of course this leaves the question how you got there in the first place. Or did something like a plane remove the floor? :) DirkvdM 09:07, 28 August 2006 (UTC)

A hang glider large enough to carry an adult may be difficult to manoeuvre through the window, especially under the pressure of an emergency. Also, it is not literally true that the building has no 13th floor. It just gets ignored. --Lambiam^Talk 09:55, 28 August 2006 (UTC)

Yes, the building has to have a 13th floor. I don't care if you call it the 14th floor, anybody who knows how to count will agree that it's actually the 13th. --Bowlhover 15:12, 28 August 2006 (UTC)

• I read about an "executive parachute" selling for $600 US or so designed for escape from a tall building. Seems like there would be a substantial risk of hitting the building and collapsing the chute, or hitting the ground long before the chute opened. With a hang glider, you would need considerable skill to soar down the street as opposed to crashing into the building across the street. Personally, I would look into rapelling or Abseiling whereby you make a controlled descent down a rope. Buy a rapelling rig and 250 feet of rope, and learn how to use it. Then you are all set. Presumably others could follow you down the rope with their own rapelling rigs. Edison 15:34, 28 August 2006 (UTC)

Executive Chute, that's hilarious! Sad thing is it's apparently real, the web site is here: [1]. Rappelling is sure to be the safer option even in the event of imminent collapse of the building you're in. Much less of a chance you will sail uncontrollably into high-voltage lines or even more likely, land atop someone who had the gall to use the stairs. --Jmeden2000 20:43, 28 August 2006 (UTC)

I've solved the 13th floor problem. The bottom half is British and the top half USian. The Brits count to 12, which the yanks call 13, so they continue with 14. :) DirkvdM 08:50, 29 August 2006 (UTC)

Speaking of Brits, wouldn't an umbrella work? Provided it is strong enough, it would at least greatly reduce the speed of descent. It seems that Brits have a tendency to fall of cliffs and such (eg Uluru) and this might be the reason. Half way down they realise that they forgot to bring their umbrella. DirkvdM 08:55, 29 August 2006 (UTC)

Not that I really think it's worth lengthy discussion, but we can thank Mythbusters (again) for showing that an umbrella will slow you for a few moments before your body weight collapses the flimsy frame and plummets you to the Earth. So... not exactly a life-saver. They're designed for small bits of falling water (sometimes not even that!) - not for Mary Poppins. CptJoker 11:03, 30 August 2006 (UTC)

Can solar panels be called "Free Energy Device"?

Can Solar Panels be called "Free Energy Device"? I asked this question because once the owner of the Solar Panel has paid for the device, they can obtain free energy forever without doing any work. Pity the amount of power (per square metre) of this device is limited. Ohanian 03:15, 28 August 2006 (UTC)

Er, no? Free energy is simply not possible. Splintercellguy 03:22, 28 August 2006 (UTC)

Solar panels cannot work without sunlight, which is a form of energy. So they can't be called free energy devices, because they need energy to work. --Bowlhover 03:26, 28 August 2006 (UTC)

I think in that context it just means that you obtain energy through something that is free: sunlight. AEuSoes1 05:41, 28 August 2006 (UTC)

In that context, yes. It is free (as in costs no money) after the initial installation. Of course, this is not completely true as maintanance plays a role. Solar power is being researched quite a bit, and some interesting and efficient technologies are being created. This is a transcript of an episode of Catalyst I saw recently. It is based on Australia's problems mostly, but it is very good. --liquidGhoul 06:59, 28 August 2006 (UTC)

It is only free as long as there is no tax on it. Once a government finds a viable way of taxing it, it won't be free much longer. There was a period in British history when each house was taxed for each window which let in sunlight, so the poorest residents bricked most of them up. It may be that sunlight will invite a tax again eventually. :) CptJoker 11:09, 30 August 2006 (UTC)

While the "per unit cost" may be zero for each kW hour, this isn't the best way to look at it. Instead, the purchase and installation price, plus any maintenance costs over the expected life of the solar panels, should be added up, then divided by the total kW hours expected, to find the cost of each kW hour. When this is done, solar energy is actually more expensive than other forms of energy, like fossil fuels. An exception exists in locations where fossil fuels can't easily be delivered, making them more expensive. StuRat 08:29, 28 August 2006 (UTC)

Indeed, one should look at the total cost of ownership. This is often not done for nuclear power either. And for fossil fuels the cost of (most of) the infrastucture is never included because those expenses have already been made. And if you want to include all the costs, you also have to include climate change. Gettting that right is tricky, because little is known about what precisely is happenning and where. But there is a rahter strong consensus that weather around the world will become less predictable and that will undoubtedly lead to bad harvests. Not just temporarily in some places, as we have experienced in the past, but constantly all over the world. The world's population has adapted to our present food production capabilities, so there is no 'room for error'. Any climate change will lead to mass starvation. What is the price of a human life? DirkvdM 09:22, 28 August 2006 (UTC)

In any case, if you mean "free" in terms of gratis, then it doesn't really work; if you mean free in terms of "no work is needed to be done," then it certainly doesn't work (the "work" that goes into sunlight comes from stellar fusion, which perfectly conserves energy and mass). --Fastfission 13:46, 28 August 2006 (UTC)

Don't all reactions perfectly conserve energy and mass (taken collectively) ? StuRat 21:58, 28 August 2006 (UTC)

About a kilowatt of solar energy hits each square meter in bright sunlight. But you may go days without bright sunlight, depending on your location, and most of us like electricity to be available 24/7. Thus you need energy storage, probably in the form of expensive batteries which must be replaced every few years in addition to the very expensive solar panels, which you cannot expect to last forever. An alternative to batteries is to convert the DC to AC and generate in parallel with the electric utiility, so they furnish power when your panel doesn't. In some places, if you generate more than you use the utility must buy your excess. But it can cost $30,000 to put solar panels on a house to generate electricity equal to their needs. I pay $77 per month for electricity, so that represents 32 year payback, probably longer than the panels and associated inverter would last. If IO put that $30,000 in an investment paying 5%, I would receive $125 per month. The economics do not appear to be there, so I would not call it free energy. Edison 15:43, 28 August 2006 (UTC)

Read my link above. The current commercial solar power is hopeless, and doesn't cover costs. That is why we needed better technology, and basically the new innovations are a lot cheaper once they are running, more efficient, more powerful and have less need for maintenance. It also covers the problem of storing energy for night (I live very close to the energy storage research centre). Solar isn't something which can be used by everyone. In Australia, we have the best opportunity to use it, as there are areas of Australia which have extremely high temeperatures, and never get overcast. It could probably be used well in America and Africa, but the Europeans need to come up with something more reliable for them. --liquidGhoul 05:31, 29 August 2006 (UTC)

Once solar panel reach the stage of mass production prices will drop considerably (but it won't get popular until it is cheap enough - catch 22). In that case it could still be one of the energy sources for Europe. Let's not make the same mistake again of focusing on one energy source, because that would likely cause other problems we can't foresee yet.

The problem of intermittent sunshine can be partly solved by using the electricity during excess hours to generate hydrogen (eg to run cars on). Also, when there is less sunshine there will often be more wind and vice versa, so it makes sense to use both sources of energy. DirkvdM 09:04, 29 August 2006 (UTC)

It's not just the cost that needs to come down, but the efficiency needs to go up. Currently, only a small portion of light hitting a solar panel is converted into electricity, which makes huge solar panels necessary to power a house, and make powering a car (with solar panels on the car) pretty much out of the question. StuRat 11:18, 30 August 2006 (UTC)

What is "Donnan effect"?

Hello all,

I'm a lost student. I found this word "Donnan Effect" in my notes but I failed to find any explaination. Can any kind souls pls enlighten me? Thanks.

It's also called the Gibbs-Donnan effect, but we don't have an article on it. See [2].-gadfium 05:40, 28 August 2006 (UTC)

It is an effect in Membrane chemistry where charged ions on one side of a semipermeable membrane will create an osmotic pressure across the membrane because they are not able to come to an ionic equilibrium. Ansell 07:04, 28 August 2006 (UTC)

There's a stubby article now. -- Plutor 15:17, 28 August 2006 (UTC)

Another grass question

Why does grass go yellow when it has been shielded from sunlight for a while? BenC7 09:02, 28 August 2006 (UTC)

Grass derives its green colour from the chlorophyll in the leaves. Chlorophyll is a green pigment, used in photosynthesis. Over time, chlorophyll breaks down, but new chlorophyll gets produced, replenishing the supply and thus achieving a balance. But when the plant receives no light, photosynthesis is not possible and chlorophyll production comes to a halt. Eventually the chlorophyll supply dwindles, and the green disappears. --Lambiam^Talk 09:48, 28 August 2006 (UTC)

so that is why a freshly unwrapped bagel is also not green? Xcomradex 10:43, 28 August 2006 (UTC)

Not if it's St. Patrick's Day. --Russoc4 11:43, 28 August 2006 (UTC)

The yellow is always present in the grass, but the green from the chlorophyll "outshines" it. I believe the yellow is caused by carotene. --liquidGhoul 11:48, 28 August 2006 (UTC)

Happens to all plants, plants so affected are described as etiolated. Rentwa 15:36, 28 August 2006 (UTC)

Maltodextrin - "the ultimate complex carb"

In the jungle of bodybuilding supplements some products contain allegedly "complex carbohydrates", only to find out that this carb is maltodextrin, glucose polymers - "the ultimate complex carbohydrate". I've always learned that maltodextrin is essentially the same as sugar in terms of absorption and causing insulin spikes, but I may be wrong. Is it possible for "glucose polymers" to ever be large enough to resemble the carbs found in say potatoes? I'd appreciate an answer very much (and I do think this subject goes under science, otherwise correct me ;) ) Jack Daw 13:02, 28 August 2006 (UTC)

I wouldn't believe anything written on a jar of bodybuilding supplement, they will lie as much as they have to in order to get a sucker to buy it. Pretty much all those formulas have in them is calories, and it's easy enough to get all the calories you need from food. You can adjust the balance of complex carbs, sugars, protein, fat, and alcohol by being selective about what you eat and drink. StuRat 21:18, 28 August 2006 (UTC)

This is a completely different discussion of course, but don't you think it's different from person to person how easy or difficult it is to eat a lot of food? Some can eat tons, others, like myself, can't eat that much without getting very sick and thus it's easier to chuck down a drink instead. Regardless, irrelevant to the original question. Jack Daw 15:59, 29 August 2006 (UTC)

Unless you are sick (stomach cancer, for example), you should have absolutely no problem consuming all the calories you need. StuRat 05:41, 30 August 2006 (UTC)

I guess I'd better call my doctor then... Jack Daw 13:04, 30 August 2006 (UTC)

Why does blueberry juice thicken cream?

The title says it all really. I've just eaten some blueberries and cream for dessert and noticed that the cream in contact with the juice was a fair bit thicker. What's going on? Perhaps people can experiment with other friut juices to see if they have the same effect - in the name of science! Theresa Knott | Taste the Korn 13:14, 28 August 2006 (UTC)

Blueberry juice is moderately acidic, and will cause the cream to curdle. Tarter, more acidic fruit juices (lemon, for example) will curdle milk or cream more rapidly. TenOfAllTrades(talk) 15:35, 28 August 2006 (UTC)

There's a knot tightening blueberry molecules that tightens cream too. -- DLL ^{.. T} 18:18, 28 August 2006 (UTC)

Nice plat on my name but bit of a tease of an answer. Does anyone know the name of these molecules so that i can do a google search? Theresa Knott | Taste the Korn 09:14, 29 August 2006 (UTC)

Referencing Wikipedia

I would like to include information pertaining to x-rays (page heading = radiography)in my MSc dissertation. Could you please tell me the authour of this page and what is the place of publication and who is the publisher - is it just Wikipedia?

Many thanks

KElly Rees

Wikipedia:Citing Wikipedia tells you what you need to know. Theresa Knott | Taste the Korn 13:35, 28 August 2006 (UTC)

I would recommend not citing it at all. For high school and above, usually Wikipedia is not taken seriously as a source and it can be negative. — [Mac Davis] (talk) (Desk|Help me improve)

Unless, of course, you want to write yet another article on, "I went to Wikipedia and XXXXXX was not correct. I didn't edit the page and fix it, so it is still incorrect. I went back later and it was fixed, but now I found XXXXX which is not correct. I still didn't edit it to fix it. Oh - it is fixed now. Let me look for something else..." --Kainaw ^(talk) 13:52, 28 August 2006 (UTC)

Of course our articles are usually well sourced, and decently well researched, you could read the citations themselves, and use those as source material. Just don't take the content directly from wikipedia. For instance, our article on X-rays, cites imagers.gsfc.nasa.gov, so if you wanted to, you could go to imagers.gsfc.nasa.gov, then cite imagers.gsfc.nasa.gov as a source. It also cites Reagan, Star Wars and the End of the Cold War, so if you wanted, you could go to a library, and take out the book Reagan, Star Wars and the End of the Cold War, given at the end of the article, complete with an ISBN. I of course have no idea what X-rays have to with Reagan, but then, I didn't write the article. The external links section is also a good place to look for a primary source, in the case of X-rays, the only one that might make a good academic source, would be probably, the BBC link all the way at the bottom, h2g2 X-Rays Edited Guide Entry. Just make sure you're NOT USING WIKIPEDIA AS A PRIMARY SOURCE, your teacher/professor isn't an idiot. If they see a lot of web based sources, the first thing they'll do, is come here, and see if you ripped off wikipedia--71.247.243.173 14:01, 28 August 2006 (UTC)

The cliff notes version: A wikipedia external links/citation section is a good reading list on a given topic--71.247.243.173 14:04, 28 August 2006 (UTC)

I've seen it done before in serious papers, but I wouldn't recommend it either like Mac Davis. It would be like referencing other tertiary sources like paper encyclopedias, except Wikipedia is "delegitimized" because anybody can edit it. Besides, all of the secondary sources are available if you want to reference those. ColourBurst 21:24, 28 August 2006 (UTC)

Yes, consult the referenced sources, but if you are looking for a specific piece of information from the document, you may be able to contact the person who wrote it by using the "discussion" page link (in a tab at the top) above the X-Rays article. I'd reccomend that you go to that discussion page and leave a message asking for the source for the information you wish to site. - Rainwarrior 17:16, 28 August 2006 (UTC)

About the 'athor' of a Wikipedia article - click on the 'history' tab above it and you will see a whole list of authors. As for 'publisher', I don't know if that term applies to Internet sites. DirkvdM 09:10, 29 August 2006 (UTC)

Quartz watches powered by the pulse of our hand

Hello,

I had heard sometime back that there used to be some quartz wrist watches earlier whose quartz crystal used to get the energy for vibration from the human pulse (as the watches are worn on the wrist). I was also told that when the watches are not worn for a long period of time, they tend to "fall behind". Is this true or somebody was taking me for a ride.

Appreciate your time and help.

Thanks and Regards,

Namit Tamhane

I believe it's more from moving around than from your pulse, but the general idea is true. See for instance the article about Automatic quartz - Dammit 13:54, 28 August 2006 (UTC)

See automatic quartz. --Kainaw ^(talk) 13:58, 28 August 2006 (UTC)

Or if that fails, you could always visit our article on Automatic Quartz--71.247.243.173 14:13, 28 August 2006 (UTC)

Or, possibly, you could check AuToMaTiC QuArTz. I forgot. Why are referring people to the same article multiple times? --Kainaw ^(talk) 14:25, 28 August 2006 (UTC)

No idea. Perhaps it's for the same reason that are writing clauses lacking an object? EdC 15:45, 28 August 2006 (UTC)

Subject actually. :P Rentwa 20:26, 28 August 2006 (UTC)

4u70m471c qu4r75 — [Mac Davis] (talk) (Desk|Help me improve)

If your watch runs on your pulse, and then falls behind, you need to view some porn to get your pulse rate back up. :-) StuRat 21:03, 28 August 2006 (UTC)

Oh, StuRat. I know exactly where your brain would have wandered if you were in my morning meeting in which the speaker began, "The Internet is not a human body..." --Kainaw ^(talk) 22:16, 28 August 2006 (UTC)

My father's pocket watch hadn't worked for years. So he gave it to me and one year I used it at Carnaval and it started running again, keeping perfect time. After Carnaval it 'died' again. Next year new Carnaval, watch ran again. It must have been the movement. Uri Geller also used this trick on tv, telling people to get an old watch that doensn't work anymore and he would concentrate and fix it. Sure, some watches started working. People tended to ignore the majority of cases where it didn't work and thought it a miracle. DirkvdM 09:18, 29 August 2006 (UTC)

Changing of Centre of Gravity

This is not homework.

While reading through an article in a magazine, I came across these Adidas Football Studs(Boots), which changed its centre of gravity to the spot where the player makes contact with the ball. Is this practically possible , and if so how ? Please explain. ---User : Veda, Sanchit

There is a shifting weight inside the Adidas Predator. That moves the center of gravity of the shoe - which isn't hard because the shoe weighs something around 300g. So, add a 200g weight and wherever the weight sits is the center of gravity. I read about them for a different reason. Some people buy them to remove the weight and have extremely light shoes. --Kainaw ^(talk) 16:01, 28 August 2006 (UTC)

Even if the shifting weight is a point mass, it could not move the centre of gravity by more than 200/(300+200) = 40% in its direction. Another issue is that as the player's leg accelerates to kick the ball, a shifting weight will lag behind, and is thus more likely to be at the opposite side of the shoe's point of contact. --Lambiam^Talk 19:12, 28 August 2006 (UTC)

Yea, that seems like a silly marketing gimmick to me, not of any real value. StuRat 20:58, 28 August 2006 (UTC)

Mr. Lambian, could you please explain how does the shifting weight lag behind. We tried it with a fully filled water bottle , but found out that the air vacuole moved in the direction of motion of the bottle and only went back after the point of impact. User : Veda, Sanchit

high pressure air plasmas

Are high pressure air plasmas always visible like ordinary plasma? and what kind of things besides air plasma can create the mechanical pressure effect caused by the heated air shockwave. These are used in pulsed impulse weapons. Curious

Actually, the main factor affecting in light emission from plasmas is the temperature. Basically, in a plasma with temperature T, the ions crashing into each other will emit photons of (average) energy $kT$ where k is boltzmann's constant. So, let's say you're looking for a plasma that emits visible light, which has a wavelength $\lambda =500nm$, and an energy $E_{photon}=h\nu ={\frac {hc}{\lambda }}=3.9710^{-19}J$ (where $\nu$ is the photon's frequency, and h is planck's constant). So you need a plasma with a temperature such that $kT=E_{photon}$. Therefore, the temperature must be $T={\frac {E_{photon}}{k}}={\frac {hc}{\lambda k}}=28,800$ kelvin. Hope that helps with the first part. --bmk

Hmmmm well the main question was "are all plasmas that can apply mechanical pressure [ such as laser propulsion and such] always visible by produced light or are there certain kinds that can greate pressure but not be seen? Thanks Robin

planets

Do planets rotate around the sun in the same plane? 209.163.204.144 18:11, 28 August 2006 (UTC)

See ecliptic - R_Lee_E (talk, contribs) 18:13, 28 August 2006 (UTC)

So, the answer is that all the planets do pretty much occupy the same orbital plane. The one exception was Pluto, which is one reason why it was excommunicated ("for deviating from the true path"). :-) StuRat 20:39, 28 August 2006 (UTC)

Thats actually not the only reason, another was it failed to clear it orbit of other objects. 69.179.249.197 20:53, 28 August 2006 (UTC)

Note that 'pretty much' means 'not entirely'. DirkvdM 09:21, 29 August 2006 (UTC)

Also note that the Moon is inclined by 5°, which is the reason we don't have a solar and lunar eclipse every month. DirkvdM 09:28, 29 August 2006 (UTC)

What kind of fish "gives birth" to baby fish instead of laying eggs?

A friend observed a phenomenon: Two tropical fish in a regular glass tank (36 x 18 x 18 inches) have produced a baby fish - without eggs. What kind of fish can this be? Where to find more info about the kinds of fish that "gives birth" as apposed to lay eggs?

Any information will be appreciated!

See live-bearing aquarium fish. --Kainaw ^(talk) 19:57, 28 August 2006 (UTC)

Some sharks also give live birth, although I doubt that's what your friend has in the aquarium! --Ginkgo100 ^{talk · e@} 21:17, 28 August 2006 (UTC)

Well, there are some small shark species that are used in aquariums, IIRC. Confusing Manifestation 00:25, 29 August 2006 (UTC)

Not beginners' aquariums. Sharks are saltwater-only and difficult to keep in an aquarium. You may be thinking of some of the various minnows with trade names including the word "shark", though. These are all egg-layers. --Ginkgo100 ^{talk · e@} 03:42, 29 August 2006 (UTC)

In any case, guppies have got to be one of the most common of aquarium fish, probably second only to goldfish, as both don't even require heated water to survive. Guppies also happen to be live-bearers. A description of the two your friend observed would be helpful. Guppies are rather small (maybe 2cm in length) and slim, with a rather oversized tail. The male guppy always has a much larger brighter, colorful and generally more impressive tail, whereas the female's tail tends to be smaller and rather bland in comparison with perhaps only a touch of colour. Does this sound like a description of the fish your fish saw? (And by the way, is it just me or isn't it odd that humans seem to be the only species of animal where the female is much prettier than the male? I know, I know, I'm just being biased :) Loomis 23:24, 31 August 2006 (UTC)

Specific Heat

What is the specific heat of PEEK & PPS powders?67.78.79.182 21:29, 28 August 2006 (UTC)Deepak

What are PEEK & PPS powders?--Light current 22:14, 28 August 2006 (UTC)

Two-hybrid System

Is the two hybrid system exclusively for detection of protein-protein interaction? I'm reading a journal article that speaks of a bacterial two hybrid system for detecting protein-DNA interaction (reference: Hurt, J. A., S. A. Thibodeau, et al. (2003). "Highly specific zinc finger proteins obtained by directed domain shuffling and cell-based selection." Proc Natl Acad Sci U S A 100(21): 12271-6) --Username132 (talk) 21:40, 28 August 2006 (UTC)

Doesn't have to be. The concept behind the two hybrid is that most transcriptional regulators can be separated into a DNA binding domain and an activation domain. As long as they are brought physically close, they function -- they don't need to be covalently linked. The two hybrid brings the two modules together through a non-covalent interaction between two other proteins, one linked to the DNA binding domain, and one to the activation domain. This interaction doesn't need to be protein-protein. Any sort of non-covalent interaction will suffice. This has been used in both "three hybrid" and "2.5 hybrid" techniques, where RNA and small molecules modulate the noncovalent interaction. I, personally, wouldn't consider your reference (http://www.pnas.org/cgi/content/abstract/100/21/12271) to be a "two hybrid" system. In it a library of zinc fingers covalently fused to the yeast Gal11 protein are created. Although the Gal11 binds to Gal4, the Gal4 in this case is endogenous, not externally applied as in the case of most of the "hybrid" experiments. Also, the interaction they are testing for is not bringing together the DNA binding domain and the activation domain, but is the DNA binding domain - DNA interaction itself. That said, Carl Pabo is a member of the National Academy and I'm not, so my opinion doesn't count much in comparison. -- 17:04, 29 August 2006 (UTC)

Friction

How does the direction of a friction force compare with the velocity of a sliding object?

Why, friction will act in the opposite direction to the sliding objects velocity, of course. --Username132 (talk) 21:51, 28 August 2006 (UTC)

I am not a ware of a link between the velocity af a sliding object and the direction of the friction. In other words, it's what 132 said, irrespective of speed. DirkvdM 09:38, 29 August 2006 (UTC)

Keep in mind that in physics a distinction is usually drawn between velocity as a vector and speed as a scalar. Thus, the friction force vector will point in the opposite direction of the velocity vector, but may have minimal to no relationship to the magnitude of the velocity vector. -- 17:10, 29 August 2006 (UTC)

Mass

I am trying to help my son with his homework and we are stumped, please help? Which has more mass, a 2-kg fluffy pillow or a 3-kg small piece of iron? More volume? Why are these answers diferent. Also if you push horizontally on a create and it slides across the floor, slightly gaining speed, how does the friction acting on the create compare with your push? THANKS!!

Well, since 3kg is greater than 2 kg, the larger mass must be the iron. But the fluffy pillow has more volume (is takes up more space) beacause its density is much lower than that of iron. Mass = Volume X density.

If you push something along the floor, friction will act in the opposite direction to your push. Now there is something called the coefficient of friction that tells you how much frictional force you get per unit weight (related to the mass of course) of the object.--Light current 22:07, 28 August 2006 (UTC)

For the crate, if the friction force were exactly equal to the pushing force, the crate would move at a steady speed. Since this is homework, I'll leave it to you're son to figure out the rest. --Gerry Ashton 22:57, 28 August 2006 (UTC)

Cutting veines

What does it call when someone cuts his arms' veines mostly because of depression? CG 21:57, 28 August 2006 (UTC)

Attempted suicide? Cry for help? Self harming? Attention seeking behaviour? 'Didn't mean it' cuts? I suppose it depends on the person and the circumstances... --Kurt Shaped Box 22:01, 28 August 2006 (UTC)

No I think the user wants the common term which is : Slitting your wrists--Light current 22:09, 28 August 2006 (UTC)

I thought it was called cutting. The disambiguation page points to self-harm. --Joelmills 01:03, 29 August 2006 (UTC)

Sorry Im wrong. Its slashing!!

That's Micheal Myers. Everybody calls it cutting, but formally and less generically "self-mutilation." See emo kid. — [Mac Davis] (talk) (Desk|Help me improve)

No, over here, its called slashing! (as in slashing tyres)

"Slash", a term used to describe cutting with forceful sweeping strokes --Light current 02:44, 29 August 2006 (UTC)

Yeah I was thinking of cutting someones throat! (No one in particular) Thats slitting--Light current 04:11, 29 August 2006 (UTC)

Thank you for the gory explanation :-P. CG 07:04, 29 August 2006 (UTC)

Keep in mind that the questioner asked about cutting veins, not cutting the skin. Cutting/slashing - whatever you want to call it - is only skin deep. It does not cut the veins, unless you make a terrible mistake. --Kainaw ^(talk) 16:05, 29 August 2006 (UTC)

Dissagree. Veins are very near the surface on the inside of the wrists, and thats why you so it there! THe purpose is suicide after all! 8-(--Light current 16:15, 29 August 2006 (UTC)

The phychiatric building here is full of people who cut themselves - not for suicide. They cut themselves on the arm, stomach, and legs. They do not cut veins. That is suicide - that is not self-mutilation due to depression. There is a huge difference between just wanting to cut yourself and wanting to kill yourself. --Kainaw ^(talk) 19:26, 29 August 2006 (UTC)

Ear pain - what does this sound like to you?

I'm going to the doctors tomorrow with this, before anyone quotes the "please consult a doctor for medical advice" rule at me. It's been a bank holiday weekend in the UK and I've been suffering with this for two days (I always seem to get ill at times like these and there's no way I'm going to walking into my local hospital's A+E with this and wasting the doc's time when people could be dying).

Anyhoo. My right ear hurts like hell inside. Ever been swimming and got water trapped inside and you can feel it sloshing around? Well, it's like that but *really* sore/throbbing too - also feels like my ear has 'popped', like when flying in a plane. My hearing is also distorted, the lobe is tender on the outside and the glands on my neck are up on that side. Tried cleaning my ear out with a cotton bud but there's nothing in the canal. Anyone have any idea what I might've got? Abscess? --Kurt Shaped Box 21:58, 28 August 2006 (UTC)

Sounds like an infection or other serious condidtion. Do not wait, Go to Accident and Emergency immediately!--Light current 22:13, 28 August 2006 (UTC)

I don't think I'm about to keel over. It's an earache, basically - aside from being irritated by it, the rest of me is just fine. Just curious about it'sall... --Kurt Shaped Box 22:17, 28 August 2006 (UTC)

Hey Kurt, try giving NHS direct a call. Hopefully they will be able to tell you what it is without you visiting a hospital!

The problem is that you could suffer permanent hearing damage if the infection gets bad enough. Burst or perforated eardrums only take a second. Anchoress 22:22, 28 August 2006 (UTC)

Yes thats why I suggested going to A&E NOW! Its not just earache as you said your glands were swollen.--Light current 01:13, 29 August 2006 (UTC)

I think my sister used the same excuses. Quite a few surgeries were needed. --Zeizmic 23:03, 28 August 2006 (UTC)

Just finished speaking to the on-call emergency doctor. She said to just take ibuprofen and paracetamol at the same time, try to get a good night's sleep, then see my usual doctor tomrorrow. If the pain gets any worse I could to go see them tonight to get some opiates but otherwise it is just an annoying earache that needs a course of antibiotics by the sound of things... --Kurt Shaped Box 23:09, 28 August 2006 (UTC)

Since you are in Britain, you could pay a quid for an answer [3] I just read this and I'm quite insulted that our good advice is worth what people pay for it. Up with the Intellectual Sweatshops! --Zeizmic 23:45, 28 August 2006 (UTC)

Well of course, people who think they've got some good answers here could actually donate £1 (each) to WP--Light current 01:17, 29 August 2006 (UTC)

Kurt, if you are saying that your lymph nodes are swollen, that could be a sign on a serious infection. If so, permanent hearing damage could be the least of your worries. I agree with the others that you shouldn't hestitate to take a taxi to the nearest ER and get an examination from a medical doctor, blah, blah. ---CH 03:22, 29 August 2006 (UTC)

I agree that this is very serious. A normal ear ache would not cause in inflammation in the ear lobe. This shows the infection has spread beyond the ear canal. I agree with the majority of advice above, and think you should go to an Emergency Room. You need some meds, quick ! PS: Have you been letting seagulls peck at your ears ? StuRat 03:29, 29 August 2006 (UTC)

BTW thats the other disadvantage of pushing cotton swabs in-- it pushes infected material IN.--Light current 04:04, 29 August 2006 (UTC)

You seem to assume this "infected material" is a solid. I would expect it to be a liquid or gel, and to easily stick to a Q-tip and then be pulled out. Of course, once the infection has gone this far, pain would likely prevent putting anything in the ear. I would suggest putting nothing but ear medication in the ear until the infection clears up, then use Q-tips to clean it out. StuRat 05:47, 29 August 2006 (UTC)

Just FYI, guys - I'm still alive after a reasonable night's sleep (my ear drum has not exploded yet, at least). Still feel pretty rough though (but no worse), and I'll be seeing my doctor today, as soon as I can get an appointment. Part of me hopes that it's somewhere easy to get to and he lances the damn thing. --Kurt Shaped Box 06:39, 29 August 2006 (UTC)

Sounds like a simple otitis externa. Hopefully you get some antibiotic drops and are better in a few days. InvictaHOG 08:33, 29 August 2006 (UTC)

From that article: Ordinarily, inflammation of the ear canal skin starts off with the loss of protective oils and ear wax (cerumen) along with minor injury to the skin. That injury often stem from attempts at self-cleaning or scratching using cotton swabs, hair pins or other implements small enough to fit in the ear canal. Prolonged water exposure (either swimming or exposure to extremely high humidity) is enough alone to both decrease the protective barrier of ear wax and to cause tiny breaks in the waterlogged skin, hence the name, "swimmer's ear". Since the swollen ear canal skin often is both itchy and painful, and sometimes associated with a feeling that something is stuck in the ear, a vicious cycle of self-cleaning or scratching can perpetuate the condition.

As I said before many times, ears are self cleaning and you shouldnt stick anything inside em (except proper earplugs--Light current 16:24, 29 August 2006 (UTC)

The doctor told me to pour warm olive oil in my ear three times a day and it should sort things. He's not my usual doctor and he's a guy I've had problems with before and who I'm pretty certain doesn't like me (I was in and out of his office in less than two minutes and he was very rough with my ear) - so I have my doubts as to whether this will work. Oh well, I can but try. --Kurt Shaped Box 00:34, 30 August 2006 (UTC)

EDIT: Can I use the word 'cunt' on the reference desk? Because this particular medical practitioner certainly is one. He's always really easy to get an appointment with because all the patients avoid him like the plague, due to him being a really bad-tempered, nasty, sharp-tongued little troll with very little in the way of compassion and/or empathy... --Kurt Shaped Box 00:39, 30 August 2006 (UTC)

Ok, I'll be the bunny. Given your description of him, why do you go to him? JackofOz 05:16, 30 August 2006 (UTC)

He certainly seems like an idiot to me. It sounds like you have a bacterial infection, so you need an antibiotic administered by drops into the ear canal, and possibly a general oral antibiotic, since the infection has now spread. Ignore that doctor and go find a competent doctor before you lose hearing in that ear or die (once the infection spreads to your brain). StuRat 05:33, 30 August 2006 (UTC)

He was the only one available at the time at the place I go to and I figured that even he couldn't screw this one up - even if he is a dislikable person (yeah, the guy's a jerk - but I thought he'd at least know his medicine). --Kurt Shaped Box 08:10, 30 August 2006 (UTC)

Any new updates ? Have you started to hallucinate from a brain infection yet ? StuRat 08:28, 31 August 2006 (UTC)

Had a very bad night, though I actually feel a bit better today (woke up and my pillow and the side of my head was covered in pus). Seeing a different doctor in a couple of hours time. --Kurt Shaped Box 12:53, 31 August 2006 (UTC)

You could request to be transferred to another doctor in another surgery so you'll never have to see the doctor you don't like again - I believe these requests are always complied with. I expect it involves filling in a form. I'm surprised you have such problems in the NHS - myself and relatives and friends have always recieved very kind and good service.

Yesterday I was going to write that they may be reluctant to use antibiotics willy-nilly as that encourages drugs resistance, but if you've got pus coming out of your ear that's another story.

I recently read somewhere about a man in the third-world somewhere who had got maggots in his ear. It was thought he had broken the tender skin by poking things in his ear like cotton buds. Once this problem is settled, I also suggest you stop putting things in your ears. I've heard of people whove badly damaged their ears by slipping in the shower while sticking cotton buds in them. 81.104.12.9 11:30, 1 September 2006 (UTC)

Feels a little better today. Whether that's due to the antibiotics kicking in, or simply because the abscess has partially drained, I'm not entirely sure. All the sounds in my right ear still sound distorted/full of reverb - my own footsteps on concrete sound particularly odd. Reggae basslines have to be heard to be believed in this condition - it's like the music has been taken to another level of greatness... ;) --Kurt Shaped Box 00:08, 2 September 2006 (UTC)

So do you have any antibiotics yet, or are they still denying that you have an infection ? I suppose they can settle the issue for sure at the autopsy. StuRat 05:49, 2 September 2006 (UTC)

Yup. Got pills. --Kurt Shaped Box 14:29, 2 September 2006 (UTC)

Plant metabolic rate.

Does anyone know of a source that describes how plant biologists measure the metabolic rate of something like a tree? --Seejyb 22:50, 28 August 2006 (UTC)

I dont know but I would put it in an enclosed environment and measure its CO2 demand.--Light current 15:20, 29 August 2006 (UTC)

Look up information on paper companies. I worked for Mead-Westvaco for a couple contracts. They put a lot of work into measuring soil and air chemicals. They measure tree heights, distance apart, root spread, animals in the area, bark density... it goes on and on. I found that the paper plant's forest had much healthier trees than the Federal forest right next to it - primarily because the Federal forest had no human intervention to improve tree health at the expense of other plants/animals. --Kainaw ^(talk) 16:10, 29 August 2006 (UTC)

biology

What is the only evolutionary mechanism that leads to adaptation 201.112.65.25 22:57, 28 August 2006 (UTC)

This sounds like a homework question, and a bad one at that. There are many mechanisms of evolution, and I don't believe any one of them stands alone in its ability to effect adaptation. --David Iberri (talk) 23:20, 28 August 2006 (UTC)

Natural Selection?

Do your own homework: if you need help with a specific part or concept of your homework, feel free to ask, but please do not post entire homework questions and expect us to give you the answers. Letting someone else do your homework makes you learn nothing in the process, nor does it allow us Wikipedians to fulfill our mission of ensuring that every person on Earth, such as you, has access to the total sum of human knowledge. Rockpocket 01:55, 29 August 2006 (UTC)

Depends on what state you live in. Down here, it is God. He made all animals as they are and anything you think is adaptation is actually just Satan playing tricks on you. --Kainaw ^(talk) 16:07, 29 August 2006 (UTC)

Luck. CptJoker 11:28, 30 August 2006 (UTC)

Headline text

Hello all, i have to do a project on parts of plants for science. can anyone tell me what websites to look at? i am really desprate coz im going away for the weekend and its due soon!!! HELP!!!!!

August 29

A Plant

• 
  Smallest one
• 
  Largest one, the color is not right in this picture
• 
  Leaves

I saw this plant by a roadside in Eastern US. The flowers aren't opened yet but look like unopened Dandelion Flowers, maybe a little bit bigger. I saw six or seven, the smallest one was half way to my knee, the largest was up to my shoulders. The biggest leaves were longer than my foot. They were soft and smooth. Where is the right place to this question? Thanks! Flyflyfly 00:01, 29 August 2006 (UTC)

This is probably the right place for the question, but what exactly is the question ? Let me take a guess: "Will this plant shoot spores into my face and make me forget all my responsibilities, while I experience pure joy ?" :-) StuRat 03:15, 29 August 2006 (UTC)

What is the plant? Flyflyfly 13:39, 29 August 2006 (UTC)

It looks like a biennial - the sort of plant that spends 1st year growing flat and 2nd year growing tall & flowering - but I could be wrong.

It can be difficult to identify a plant from photos - you normally need to examine the plant in detail. Best way is with a flora with a key (simple qs - like 'does plant have simple or compound leaves?'). Buy a flora or maybe these can help. Rentwa 13:58, 29 August 2006 (UTC)

Antacid

Can one take too many antacid tablets and cause damage to the stomach? Can lack of acid in the stomach cause damage to the stomach (I didn't take any antacids, by the way)? --Shanedidona 00:07, 29 August 2006 (UTC)

Antacids typically contain very mild bases; they shouldn't damage the stomach even if taken to excess. In principle, a massive overdose of antacids may cause alkalosis: an increase in blood pH to unhealthy levels. If you find that you're taking antacids over a long period of time – weeks – then you might want to consult your physician; you may have a stomach ulcer or other medical problem that requires attention. TenOfAllTrades(talk) 01:13, 29 August 2006 (UTC)

I would think a lack of acid would slow down digestion, and perhaps make it less effective. StuRat 03:08, 29 August 2006 (UTC)

Stomach acid is not for digestion, it is to kill any foreign bodies (eg. bacteria etc.) that might be inhabiting your food, enzymes are used for digestion. Low stomach pH causes an increasedrisk of infection, which can be fatal is maintained at a low state, providing infection. Philc _T^E_C^I 12:48, 29 August 2006 (UTC)

Don't you mean high stomach pH (i.e., less acid)? —Keenan Pepper 03:55, 30 August 2006 (UTC)

If your stomach had no acid in it, would that hurt? --Shanedidona 03:47, 29 August 2006 (UTC)

Its hard to say. What happens if you eat lots of mild alkali-- does that hurt?--Light current 04:07, 29 August 2006 (UTC)

We have an investigation into antacids as a Yr 9 (13-14-year-olds) project for our pupils. The actual amount of base per tablet is minute, and cannot possibly neutralise all the acid in the stomach. Rather, the conclusion is that they are intended to neutralise excess acid above the sphincter, and thus reduce discomfort. Also, the slower they dissolve, and the slower they slip down, the more effective they are. --G N Frykman 11:26, 29 August 2006 (UTC)

Be careful about prescription medicatons. Certain ones (I don't know off hand which) require stomach acid to function properly. Lowered stomach acids due to antacids can cause the drugs to become ineffective, or may even result in potentially severe side effects. -- 14:49, 29 August 2006 (UTC)

Also, this isn't related to the stomach, but overuse of antacid products (Enos and baking soda more than antacid pills) can negatively impact heart function, due to the mineral salts' altering electrolyte levels. Anchoress 14:53, 29 August 2006 (UTC)

Excellent

I don't have a question--I want to pass on congratulations. I looked up Pluto on your site and was very happy to see that the information has just been updated. So often websites are created and never refreshed and kept up to date. You are doing a wonderful job. Thank you.

On behalf of our astronomy editors, thank you for your kind words. Rockpocket 01:51, 29 August 2006 (UTC)

You could count on seeing it updated within an hour of the decision. When the bombs went off in Bombay, I went straight to Wikipedia for the true, clear, concise information all in one place — [Mac Davis] (talk) (Desk|Help me improve)

Looks like you need to update your knowledge base, Bombay is now Mumbai. :-) StuRat 03:10, 29 August 2006 (UTC)

So do terrorists in Mumbai now explode "mumbs?"Edison 15:28, 29 August 2006 (UTC)

Another one of the goodies of Wikipedia - if you go to Bombay you automatically end up in Mumbai. DirkvdM 09:46, 29 August 2006 (UTC)

And if you've a date in Constantinople, she'll be waiting in Istanbul. Melchoir 14:35, 29 August 2006 (UTC)

And, with my luck, I'd be stuck in Byzantium. :-) StuRat 23:33, 29 August 2006 (UTC)

Seagulls!

Can someone please explain to me why the Science RefDesk is so devoted to every possible aspect of seagulls? Once you're at it, are seagulls Hallal? Loomis 03:25, 29 August 2006 (UTC)

I thought we had banned them last week.--Light current 04:00, 29 August 2006 (UTC)

Followup question

How long can a joke go before it stops being funny? This is not homework. – ClockworkSoul 04:13, 29 August 2006 (UTC)

Who knows? Raul654 04:31, 29 August 2006 (UTC)

Bonus question: Arrange these six seagulls into one arrow. Anchoress 07:26, 29 August 2006 (UTC)

That's a trick question, they're already in an arrow. - Mgm|^(talk) 08:26, 29 August 2006 (UTC)

Which dance is the one in the front doing? DirkvdM 09:49, 29 August 2006 (UTC)

THe funky chicken?--Light current 15:08, 29 August 2006 (UTC)

He's not dancing, he's got gum stuck to the bottom of his foot. Oops, no, on further examination, he stepped in some guano. Anchoress 14:39, 29 August 2006 (UTC)

From now on, I'm not going to even bother to archive the seagull related questions anymore (: That should save a few hours of my time--VectorPotential^{71.247.243.173} 15:12, 29 August 2006 (UTC)

It is mostly User:Kurt_Shaped_Box's idea. He is constantly asking questions about seagulls bagels and catfish. — [Mac Davis] (talk) (Desk|Help me improve)

Do catfish masturbate? – ClockworkSoul 19:44, 29 August 2006 (UTC)

In Kurt Shaped Box's defense, I have observed him asking only serious questions about seagulls. Melchoir 06:07, 30 August 2006 (UTC)

In the seagulls' defense, I don't think I've ever observed them doing anything that deserved a banning.  freshofftheufoΓΛĿЌ  14:50, 30 August 2006 (UTC)

War-plane crash

Hi! which kind of war-plane has the highest frequency of crashing down ...NOT due to enemy-attack, but 'cause of technical-failure ? Also, what is the commonest technical problem that leads to a war-plane crash(in general) ?? --Pupunwiki 04:05, 29 August 2006 (UTC)

Probably some helicopter. Melchoir 04:09, 29 August 2006 (UTC)

I would guess that would be a plane with few production models, like the V-22 Osprey. StuRat 05:41, 29 August 2006 (UTC)

I would guess the reverse, if you only look at the total frequency (not the average per plane). DirkvdM 09:51, 29 August 2006 (UTC)

The most common cause is probably engine failure. Engines aren't designed to run at full power for long periods of time, but because of the speed required for dogfighting, and the power required for a bomber to take off with a full load, warplane engines are overstressed on a regular basis.

As for individual models, a number of World War I aircraft had problems with aerodynamic instability, where a pilot could easily find himself in a flat spin or other uncontrollable situation. In World War II, the B-26 Marauder had a reputation for crashing if an engine failed on takeoff. --Serie 23:08, 1 September 2006 (UTC)

I vaguely remember hearing of some Fokker, German, 1920's or 1930's, called a "widowmaker"; less than a hundred were made, and two-thirds of the pilots were killed. Google knows naught, though. linas 23:11, 2 September 2006 (UTC)

Optimal slope

This is not a homework!

If you are making a zigzagging road as on this picture from Machu Picchu [4] what is the optimal slope so that it requires the least amount of energy to walk to the top. I have thought about this that it is the same as the optimal slope of a ramp to elevate yourself to a given height without the zigzaggings and does not depend on the slope of the mountain. If we have a formula that gives the energy E(α) required by average person to walk up a slope at the angle α per meter of gained elevation then we want to minimize E(α). When α goes to zero this goes to infinity and when α goes to a right angle it will also go to infinity. Is this my reasoning correct? Are there formulae or tables for E(α)? Also I think the optimal slope may be different for bicycles and cars, is that slope known? Thank you for your attention. 199.3.224.3 07:11, 29 August 2006 (UTC)

For this to be realistic you'd have to calculate in the soil and the person. With a sturdy surface a steeper angle would proabably be more efficient. And I have walked up hill-tracks that were obviously built with less fit people in mind, with a very shallow slope. I tend to ignore them and go straight up. Then again, this may just 'feel' less tiring because the track is so boring. DirkvdM 10:51, 29 August 2006 (UTC)

(via edit conflict) In an ideal situation (negligible friction, etc), the energy required to raise a mass by a height of h is mgh, and is independent of the path taken, so in that case there is no optimum, and in fact the only problem case is if the angle is zero, when you will never reach the top and hence never expend any energy. On the other hand, the fastest comfortable angle is probably something like 30° or so (I seem to recall that's around the maximum grade for roads and such), but I don't know of any references or reasoning for that. Confusing Manifestation 10:53, 29 August 2006 (UTC)

Thats not true, you seemed to have failed to account for the fact moving uses energy. The optimal slope would be a straight line to the top at 90 degrees, that way you move the load the minimum distance, but the same height. Philc _T^E_C^I 12:44, 29 August 2006 (UTC)

Yes, but that energy can (in theory) be recovered at the end. The only energy that has to be used up is that which is converted into gravitational potential, which is independent of the path taken. EdC 17:03, 29 August 2006 (UTC)

Let's assume a paved road. Having hiked and negotiated some slopes, I can assure you that climbing at a steep angle uses up a lot more energy for the same height difference. And going downhill at a steep angle kills you. I found an online article claiming that for going uphill a slope of 15° is best, and for downhill 10°.[5] But no formulas or actual data of energy expenditure for different slopes. --Lambiam^Talk 18:30, 29 August 2006 (UTC)

THe potential energy at the top is independent of the route taken. So whats the real question?--Light current 19:52, 29 August 2006 (UTC)

Have you heard of metabolism? Animals (including humans) expend energy to move their muscles. That energy is not waiting for them at the top of the mountain to be reclaimed. It is lost, gone, pfft. --Lambiam^Talk 20:12, 29 August 2006 (UTC)

The HP ScanJet 4600 Flatbed Scanner

• http://reviews.digitaltrends.com/review_printerfriendly1694.html

How does it work? Where is its sensor array? -- Toytoy 08:21, 29 August 2006 (UTC)

same way as any other i'd say. the array will be on a track, and will currently be inside the casing, and will be dragged across when scanniong starts. Xcomradex 08:43, 29 August 2006 (UTC)

From the review: "The see-through window is a nice touch, as it is somewhat mesmerizing to watch the glowing scanner carriage work its way down your document." Normal scanner, though at 3 lb it probably uses an LCD array for its light source (which makes it a lot lighter than the bulb scanners). It just seems to not have an opaque cover. I wonder if that creates problems in certain types of environments—I've noticed that with my scanner if I try to use it with the cover open in a very sunny environment it can have a more washed-out feel on the colors, though I don't know if that is just me imagining things or not. --Fastfission 15:38, 29 August 2006 (UTC)

Intubation for blocked tear duct

--Fayray 13:05, 29 August 2006 (UTC)would like to know the risk factors and percentage success rate for this surgical procedure. If it is not successful, is the patient likely to be worse off than before undergoing the operation?Fayray 13:05, 29 August 2006 (UTC)

If this is a real and not hypothetical case your doctor will unquestionably be better placed to answer this question than Wikipedia. DJ Clayworth 15:23, 29 August 2006 (UTC)

My grandmother underwent what would likely be the procedure you're referring to, and that went well. :-) I know the sample size isn't too great but it's better than nothing. —Bromskloss 15:56, 29 August 2006 (UTC)

pH meter and buffer solutions

Why doesnt a pH meter work in a weakly buffered solution?

they do work. pH meter. Xcomradex 00:08, 30 August 2006 (UTC)

• If you calibrated the thing properly using at least 2 (preferably 3) standard buffer solutions, it should.- Mgm|^(talk) 07:48, 30 August 2006 (UTC)

Some pH electrodes have trouble with very low ionic strength solutions. There are electrodes on the market that are better designed to deal with this (I think mine is a STAR electrode from Fisher). ike9898 13:39, 30 August 2006 (UTC)

Movement

Why does movements create heat? Correct me if I'm wrong and please explain! Thanks!

Movement only creates heat where there is friction. An object moving thru a vacuum doesn't create heat. StuRat 13:42, 29 August 2006 (UTC)

But an object moving along the ground, or through air or water, does. So why does friction create heat? As you can read in the friction article, according to the law of conservation of energy, no energy can be lost when friction slows something down. The energy is therefore transformed into heat.--Shantavira 14:26, 29 August 2006 (UTC)

Perhaps because bonds are being formed and broken between the two objects as they move against each other, and energy is required to break the bonds? (Chemist's answer) Rentwa 20:15, 29 August 2006 (UTC)

The elevator broke

Hi,

An old physics question. A person is standing in an elevator on the 30th floor of a building holding a tennis ball. The chain/rope of the stationary elevator cracks and it starts falling down under free gravity. At that moment he releases the ball. Do you think the ball will hit the flor of the elevator before the elevator hits the ground 30 floors below?

Namit.

The old physics answer - No. If we assume there are no forces on the elevator or ball (such as friction or air resistance) both are under free fall, and are subject to just the force of gravity, and thus the same net acceleration. If we assume that both the elevator and ball start at rest, their downward velocities will always match, and will always track each other's position, ending up at the floor at the same time. -- 15:05, 29 August 2006 (UTC)

However, when we throw in air resistance, I expect the answer is "yes". I think the elevator is more likely to reach terminal velocity, as the tennis ball is falling through air that is (to some degree) also falling with the elevator. Less relative velocity should result in less drag on the ball. — Lomn | Talk 15:12, 29 August 2006 (UTC)

Man, why is physics so macabre? --Fastfission 15:16, 29 August 2006 (UTC)

This sounds like a homework, but I cannot know that so I'll give you the benefit of the doubt. My reasoning will be divided into the following parts:

1. Will the ball fall faster than the elevator? (Answer: Yes)
2. Will the ball fall so much faster than the elevator so that it will hit the floor before the elevator hits the ground? (Answer: I would guess so.)

Let's start with question 1. My personal experience tells me that the shaft is not an awful lot wider than the cage that moves in it. This means that as the cage falls downward and pushes the air under it aside, this air will have to squeeze through the rather narrow space between the cage and the shaft wall. By consequence, the speed of the cage will be slow compared to what it would be in empty space. The ball will of course not have much of this problem. Furthermore, since the air inside the cage will move at the speed of the cage (and thus nearly the speed of the ball), the ball will have a low speed relative to the air around it and will therefore not experience as much drag as the cage itself would, even if the latter wasn't confined to a shaft.

Now, to answer question 2, we need to know not only that the ball falls faster than the elevator, but how much faster and how long it will take before the cage is down. Well, I can't answer that, but intuitively, I would say Yes, I think the ball hits the floor before the cage hits the ground. —Bromskloss 15:20, 29 August 2006 (UTC)

I was actually thinking about falling elevators earlier today and wondered if they could be used for simulated weightlessness! :-) (I know you want it, everyone does, right?) You would need a high building for it to be any fun, and perhaps actively pushing the elevator downward (or even without actively pushing it, you might achieve moon like gravity). It could perhaps be cheaper than parabolic flight, don't you think? —Bromskloss 15:33, 29 August 2006 (UTC)

To nitpick: if the elevator is of a post-1857 design. it should have something like the Otis safety device which automatically applies brakes if the cable breaks, thriller movies notwithstanding. Edison 15:34, 29 August 2006 (UTC)

Real physicists use pre–1857 elevators! —Bromskloss 15:40, 29 August 2006 (UTC)

Theoretically, as soon as the cables of the elevator are snapped, the ball will start falling with the same acceleration as the elevator. In relation to the person, the ball will be at the same height as tht when the person drops it. This is a clear cut case of weightlessness. Now as soon as the elevator hits the ground , the ball shall take normal time as on land to hit the ground. Practically, taking air resistance into consideration, the speed of the elevator will reduce and thus also its acceleration. This will cause a disbalance in the acceleration of the ball and the elevator. And thus the ball will hit the ground before the elevator hits the ground.

Also, remember Galileo's Ecperiment frm the top of the Leaning tower of Pisa. When two objects are dropped frm a common height, they land in the same time duration. User : Veda, Sanchit

On the moon (without the air), you can even do it with a feather and a hammer. :-) —Bromskloss 16:58, 29 August 2006 (UTC)

Alarms during a thunderstorm

Why do car / house alarms activate during a thunderstorm? Someone told me that the static in the air sets them off but other electronic devices seem to work fine. 62.25.109.194 15:23, 29 August 2006 (UTC)

theyre not properly designed for EMC electromagnetic compatibility--Light current 15:28, 29 August 2006 (UTC)

Vibration of the house windows or of the car might set off the sensors. As noted above, the electrical field from the lightning, or electrical fields induced in the power circuits might trigger the alarm. Utility electric power may be momentarily switched off and back on by the utility high voltage lines to clear fault conditions when lightning strikes power lines, and some alarms may be set off by the power being removed and restored, especially if the alarm backup batteries are worn out. Edison 15:38, 29 August 2006 (UTC)

Or basically, they are too sensitive to unimportant thinks (a bit like some WP editors)--Light current 15:46, 29 August 2006 (UTC)

You're going to get yourself in trouble again! — [Mac Davis] (talk) (Desk|Help me improve)

This is not a personal attack! Also I include myself in that bracket) 8-)--Light current 19:39, 29 August 2006 (UTC)

Ah, but aren't you a person? Or me, who would like to point out that you don't indent properly? DirkvdM 09:04, 30 August 2006 (UTC)

How does that explain why car alarms go off for fireworks?  freshofftheufoΓΛĿЌ  13:13, 1 September 2006 (UTC)

Oversensitive door alarm. When a firework explosion shakes the car, it opens the door just a crack, and some car alarms interpret that as an attempt to break in. --Serie 23:25, 1 September 2006 (UTC)

shackle poisoning

Hello,

I was wondering what shackle poisoning is. I've heard that it is the constant rubbing of chains on peoples legs, mostly on chaingangs. I was just wondering what exactly it is and why does it kill people.

Thank you.

--Jerry

If you Google for it, you will find that the term only appears in two main instances - both authored by the same man, Wayne Perryman. It is possible that he is giving a term to this problem that nobody else uses. It is highly unlikely that shackles poison anyone. It is more likely that they have open wounds that get infected. --Kainaw ^(talk) 17:56, 29 August 2006 (UTC)

A hypothetical question about teleporters.

In films such as The Fly, teleporters work by 1. Identifying each individual cell in the body of the traveller; 2. Destroying the body of the traveller; 3. Transmitting the data to another machine and 4. Reproducing each individual cell in the precise order they were in earlier. To me, it seems that rather than teleporting a person from one place to another, they've just killed the person and replaced them with a clone. Thoughts? Corrections? Wouldn't this be the ideal way to commit suicide, as your consciousness ends but your family and friends are unaware of any change? Pesapluvo 17:16, 29 August 2006 (UTC)

If you believe that life and consciousness are solely a manifestation of a collection of physical, chemical and electrical processes, and those processes continue unabated after being teleported, then I think it follows naturally that your life continues. If you believe that life is more than a mere manifestation of material properties, as many people do, then I think that the answer would have more to do with faith than with science. Dragons flight 17:24, 29 August 2006 (UTC)

Yes, if you have sufficiently detailed knowledge of what you were teleporting, you can recreate the same thing at any other point in space. No need to destroy the original, but then there would be 2 copies of you. A better idea would be to create a wormhole between the 2 locations. The two locations then effectively become one and you can just walk thro it (intact)--Light current 17:28, 29 August 2006 (UTC)

In quantum teleportation you must destroy the original. — [Mac Davis] (talk) (Desk|Help me improve)

You mean to read some thing properly you must interfere with it to a destructive extent? Yes that could be right. That of course is what happens on WP! 8-)--Light current 19:36, 29 August 2006 (UTC)

There is also the problem of multi-dimensional existense. Sure, we know how we appear in 3 dimensions. How do we know there isn't some fourth or fifth dimensional extension of our being that, if we copy just the 3 dimensional view, is missing? That must be included in Light Current's "sufficiently detailed knowledge" disclaimer. --Kainaw ^(talk) 17:51, 29 August 2006 (UTC)

Yes I suppose it must but I think Im happy with my 3 dimensions ATM--Light current 18:42, 29 August 2006 (UTC)

This is a problem in what's called personal identity. In general, to answer this question, one must decide what makes one person the same person at two different times. For instance, what is it about me circa 2006 that makes me the same as me in 1995, but not the same as my father in 1995 (or anyone else for that matter)? Much of my constituent matter is different between the two times, but that doesn't seem to matter in personal identity. If your interested, the Stanford encyclopedia of philosophy article may provide some additional food for thought. --best, kevin [kzollman][talk] 19:30, 29 August 2006 (UTC)

Re personal identity: Assuming it's made possible by the progress of medical science, would you have a brain transplant when your brain fails? --Lambiam^Talk 20:20, 29 August 2006 (UTC)

I would have a body transplant instead! (before the brain failed)--Light current 20:31, 29 August 2006 (UTC)

The Emperor's New Mind is an interesting and accessable book with lots of speculation on this very question. MeltBanana 01:13, 30 August 2006 (UTC)

Another problem with this in Star Trek is that if it is just the transmission of information, then distance should be no problem, so why do they need spaceships? DirkvdM 09:11, 30 August 2006 (UTC)

The biggest problem in Star Trek was that they didn't require a station at the other end to reassemble the person. I would have made the Enterprise and other ships have the primary purpose of setting up transporter stations on other worlds. This would naturally have put them on the edge of the explored universe, so they still would have had a chance to encounter new life forms and green women, thus giving Kirk an opportunity to unzip his boots, among other things. :-) StuRat 20:45, 30 August 2006 (UTC)

I H8 EndNote

Does anyone else have problems using EndNote to search for references from the PubMed database? It's always saying that it can't find any results even though I'll eventually find exactly what I'm looking for using different search parameters, despite the thing I'm looking for matching the parameters I originally used. It's rubbish. --Username132 (talk) 17:53, 29 August 2006 (UTC)

I just use Entrez Pubmed at NCBI. Xcomradex 00:11, 30 August 2006 (UTC)

I've used EndNote for years, but I NEVER use EndNote to search for new references I don't already have. You are right, it is buggy and clunky, so I recommend just searching Pub Med directly as the last respondant suggested. ike9898 13:34, 30 August 2006 (UTC)

Hyperventilation

I read in a science book that some people think that hyperventilating will help them hold their breath longer, but really this doesn't help at all and might be dangerous. I was just wondering; if hyperventilating doesn't help you hold your breath, what does? What are you supposed to do in order to hold your breath longer? The hyperventilation article doesn't say anything about holding your breath. --Jonathan ^talk 18:17, 29 August 2006 (UTC)

Stopping breathing (or death). THe first sometimes leads to the second-- or vice versa--Light current 18:43, 29 August 2006 (UTC)

If you want to be able to hold your breath for longer, practice holding your breath. That's how the insane deep-sea divers do it. Would doing a lot of cardiovascular exercise help too? — [Mac Davis] (talk) (Desk|Help me improve)

The excersize I used when I was young (which worked well) was to breath out as much as you can, then blow out three more times. Then, breath in as much as you can, then gasp in three more times. Repeat. It doesn't only allow you to hold your breath for a long time, it also allows you to blow air (ie: through a trumpet or saxophone) for much longer. --Kainaw ^(talk) 19:00, 29 August 2006 (UTC)

I've actually been trying to train my lungs for swimming purposes. Should I hold my breath in/out for any length of time or is it good enough to just do the inhaling and exhaling?  freshofftheufoΓΛĿЌ  14:40, 30 August 2006 (UTC)

Yeah just tried that!. I think this would increase lung capacity and would therefore help to hold breath longer.--Light current 19:28, 29 August 2006 (UTC)

Regularly playing a wind instrument also increases your lung capacity and your ability to hold your breath. --Lambiam^Talk 20:24, 29 August 2006 (UTC)

I think you might be interested in reading Shallow_water_blackout, which was conveniently linked to at the very bottom of the hyperventilation article. --Borbrav 20:30, 29 August 2006 (UTC)

Yeah, thanks, that's just the article I needed. --Jonathan ^talk 23:47, 29 August 2006 (UTC)

Pardon the original research but in my youth I worked at breath holding, reaching a personal best of 3 minutes 45 seconds. There is no question, based on my experiments, that hyperventilating prior to breath holding extends the time one can hold the breath without passing out. Michael Faraday, the 19th century chemist and physicist, working with Humphrey Davy first isolated several gases and did much work in labs where lethal gases were sometimes produced. He wrote an experimental note in one of his books to the effect that if one wishes to rescue a person who has passed out in an atmosphere dangerous to life, it is a good idea to take several deep breaths before dashing into the room and pulling out the person who has passed out, being careful not to breathe in the noxious atmosphere. He noted that he had used the technique a number of times. As always, seek medical advice before trying anything you read about on Wikipedia. Edison 03:46, 30 August 2006 (UTC)

The urge to breathe typically comes from the elevated carbon dioxide which accumulates when you are not breathing. When you hyperventilate, you bring your carbon dioxide down to quite a low level. Therefore, it has a longer way to go to get to the level where you feel the extreme urge to breathe. Surprisingly enough, low oxygen is a much less potent stimulus to breathe. This is why hyperventilation allows you to hold your breath longer. InvictaHOG 08:39, 30 August 2006 (UTC)

Destructive interference, audio?

Let's say two guys talk at the same time. One guy is talking in completely the inverse phase of what the other is, so that in theory, the audiowave peaks where the other audiowave reaches its bottom. Realistic restrictions part aside, would the two guys cause the sound to disappear at some place? Thanks! Henning 19:18, 29 August 2006 (UTC)

Yes. It happens here quite often!--Light current 19:25, 29 August 2006 (UTC)

Destructive interference is essentially what noise-cancelling headphones are designed to create. -- Scientizzle 00:22, 30 August 2006 (UTC)

If two points are generating inverse waves, then in 3d space, at some points they will destructively interfere (producing no sound), and at other points the overlap will produce contructive interference that will double the sound intensity. Raul654 00:23, 30 August 2006 (UTC)

To try this experimentally, one might take a monophonic recording, and reverse the leads to one of the 2 speakers. Then move along a line equidistant from the line connecting the speakers, perhaps plugging one ear, and se if there is a point where the sound in at a minimum. Edison 03:49, 30 August 2006 (UTC)

Pseudoscience

I know that Pseudoscience makes claims that its predictions are supported by experimental evidence. However, a pseudoscience concept put forth fails under the rigors of experimental testing within the framework of the scientific method. Often the methods of testing, data collection, and conclusions are flawed by a preconceived agenda. Can you give me an example of a pseudoscience concept or product and an explanation why it is based on false science or logic. I know alittle about this but not enough to give my son the right logic for his studies. THANKS

What about divining, seance, astrology to start.--Light current 21:13, 29 August 2006 (UTC)

Creation Science is one of the worst offenders. I have absolutely nothing bad to say about Christianity or Christians, but Creation Scientists come up with some of the most inexplicable, nonsensical garbage I've ever heard labeled as science. For example, one popular creation science theory says that the reason lizards grew so big (into dinosaurs) was because there was a shell of solid ice around the entire earth protecting them from harmful UV radiation. And that the rain for The Flood came from God melting the ice. Not only would such a construct be completely unstable (hasn't anyone read The Ringworld Engineers?), but it wouldn't do squat to raise O2 levels or make dinosaurs. --Froth 21:18, 29 August 2006 (UTC)

There is a list in our article on pseudoscience. Phrenology is always a popular example, and less controversial than creation science. It was generally considered bad because the practitioners often changed their predictions when they were falsified. I remember hearing about one case where they examined Rene Descartes skull and found that phrenology predicted he would be dumb. In response the phrenologists downplayed Descartes contributions rather than reject their theory. The last days of phlogiston chemistry are like this too. Phlogiston was a substance that supposedly left an object when it was burned. When experiments demonstrated that objects gained weight when burned, phlogiston chemists suggested that perhaps phlogiston had negative weight.

Often times, pseudoscience is so labeled because their claims are not falsifiable. That is, no experiment can ever disprove them. Conspiracy theories often fall into this category: "There is a government conspiracy. Anyone who tells you there isn't is just part of it." There is some debate in the philosophy of science over whether falsifiability is an appropriate criterion, however. If your interested, see Demarcation problem. --best, kevin [kzollman][talk] 21:40, 29 August 2006 (UTC)

I would include chiropractic, as terms like subluxation are vague and are used to diagnose and treat just about any condition, without any actual evidence. StuRat 22:27, 29 August 2006 (UTC)

I would add that the word itelf, subluxation, has a well defined meaning in medicine (it refers to a partially dislocated joint or eye). It is only in certain contexts that this word has an alleged vague meaning.Tuckerekcut 13:36, 30 August 2006 (UTC)

Alex Chiu's 'eternal life through the power of magnets' theory springs immediately to mind. --Kurt Shaped Box 02:54, 30 August 2006 (UTC)

String theory was recently criticized as non-falsifiable, but Brian Greene is extremely smart and he is a proponent of it so what can you do. Edison 03:52, 30 August 2006 (UTC)

Some suggest psychiatry is non-falsifiable and thus a pseudoscience (demarkation problems notwithstanding), see Anti-psychiatry and Biopsychiatry controversy for more information. Rockpocket 05:11, 30 August 2006 (UTC)

According to Karl Popper, psychoanalysis is non-scientific because it is not based on falsifiable hypotheses. However, I don't think he felt the same way about psychiatry in general. He did criticize Marxism along the same lines. Bhumiya (said/done) 05:12, 5 September 2006 (UTC)

Closed universe theory / edge of the universe

If it's correct, what will happen when expansion slows to a halt and starts contracting? For that matter, what will the universe look like when expansion slows enough to see light from the very edge of the universe?

Also, since the universe is expanding at only very nearly the speed of light (and not the speed of light), what is happening to those few photons that overtake the "edge"? Is that energy lost from the universe? Or is the expansion of the universe expansion through time, not space? I'm very unclear on this.

And if the universe starts contracting, what will happen? Will cohesive masses get smushed together (the galaxy being pulled into a gigantic quadrillion-galaxy ball of plasma in the center of the universe for example) or would atoms just get closer or something (us relativistic creatures never noticing until microcircuitry -and brains- stop working from the interference)?

--Froth 20:50, 29 August 2006 (UTC)

I believe we can already see light from the edge of the universe!. Also, its only the farthermost stars that are travelling fast according to Hubble's Law.--Light current 21:16, 29 August 2006 (UTC)

I know that only the farthest systems are travelling fast, what does that have to do with my question? After thinking about it some more, I think maybe I have a flaw in my first question- I had been thinking of the universe as a defined line, like the edge of an expanding sphere, with stars drifting into this newly-opened space at some later point, with the "edge" roaring onward, claiming more volume for the universe. But I guess what's really going on is that the "size" of the universe is defined by the presence of matter streaming outwards from the big bang- in other words that stars and photons and neutrinos can just move outward as far as they want -even if they were to suddenly jump a trillion light-eons forward- and just keep encountering space.. nothingness. Or was I right originally, and the presence of energy or matter "unlocks" space in a way, and with the first change that.. that location has ever experienced initiates the flow of time there and so the universe barrier isn't just arbitrary, it's real and measurable. I know I'm twisting words a little, especially with time -that is what time really means anyway, measurable change- but I'd be interested if there are any real scientifikal theereez on this topic. I don't subscribe to the theory of the big bang btw, im just curious about it --Froth 21:28, 29 August 2006 (UTC)

Yeah-- theres no 'space' w/o mass--Light current 21:31, 29 August 2006 (UTC)

Partial answers/comments: Keep in mind the difference between the universe and the observable universe. If a star is sufficiently far away that its distance relative to use is growing at faster than the speed of light, its light will never reach us. The limit of the observable universe is the region just close enough that objects there are moving farther away at just less than the speed of light. If the universe starts shrinking, it just means that all the matter will stop moving away from us and start coming together. The forces inside atoms that keep electrons away from the nucleus will continue to hold, so the atoms themselves won't shrink (same reason atoms aren't being slowly pulled apart by the expansion of the universe: the distance from the electron orbits to the nucleus might be very slowly increasing, but the orbits just get pulled back at the same time). digfarenough (talk) 22:06, 29 August 2006 (UTC)

Also, I would like for everybody to note that expansion theory proposes that spacetime is expanding, and not anything else. The distances are increasing, causing cosmological redshift/blueshift. Distinguishing between coherence and decoherence is vital when discussing "the expanding universe idea."— [Mac Davis] (talk) (Desk|Help me improve)

What do you mean by "distinguishing between coherence and decoherence"? --Lambiam^Talk 04:36, 30 August 2006 (UTC)

For the notion of expanding space (not spacetime) see Metric expansion of space. The latest news is that cosmologists appear to agree that the universe will not eventually contract, but that the expansion is instead accelerating; see Dark matter. For the universe having no edge, see Shape of the Universe. For all we know, it may be infinite. --Lambiam^Talk 04:46, 30 August 2006 (UTC)

In particular, don't assume that "finite universe" = "universe has an edge", at least in the dimensions familiar to us. Spacetime doesn't have to be flat, even asymptotically, so it can curve in on itself. Consider the good old balloon analogy. The surface of the balloon is finite, but in its own geometry it has no edge - travel far enough along it in one direction and you'll end up back where you started, or fairly close to it. Certainly it has a boundary when it's considered as a sphere embedded in familiar 3D geometry (in fact in that case it's all boundary), but that requires leaving the geometry native to the balloon and, if we expend our analogy to the universe, is not something we could easily detect. Confusing Manifestation 14:09, 30 August 2006 (UTC)

Epilepsy

why would some sorts of fast flashing lights and/or random high pitch sounds, supposedly cause an epileptic seizure?. --Cosmic girl 21:20, 29 August 2006 (UTC)

I'm not exactly sure why, but realize that epileptic seizures are a complex thing, cause by some pretty wacky triggers- hot water on the head for example. The correlation between rapidly changing images/sounds and rapidly jerking limbs while seizing may be just a coincidence. See also Photosensitive_epilepsy, though it's not ver y appropriate to your question --Froth 21:36, 29 August 2006 (UTC)

thank you!!!!! :D I didn't know about hot water! interesting... --Cosmic girl 21:47, 29 August 2006 (UTC)

Well, seizures occur when there is too much excitation of neurons: if too many neurons start firing, then they drive other neurons (or themselves) to fire too much, which in turn drive others, etc. and soon way too many neurons are firing (sort of like microphone feedback where all you get is the feedback and no real signal anymore). If some of those neurons are motor neurons, then limbs go a-flailing. The reason high frequency flashing lights can lead to a seizure is that many neurons in the visual system are sensitive to changes in their input. A steady light means no changes, so some cells would only fire when the light is first turned on (and other cells fire when the light goes off). If the light is flashing, then those change-signally neurons start firing pretty much constantly, which leads to the cycle described above. Normally there's a system of feedback inhibition in place, which makes it harder for cells to fire if many are firing, but if that system fails for some reason, you get epilepsy. digfarenough (talk) 22:00, 29 August 2006 (UTC)

Note that flashing lights and advertisements are intensely annoying to many without epilepsy, for the same reason, it's an excessive level of visual input stimulus. StuRat 22:08, 29 August 2006 (UTC)

Chinese pheasant

While researching for Denver Zoo, I came across a reference to "Chinese pheasants." Does anybody have any idea what species these are? Neither Wikipedia nor ITIS have answered this question. Could it be the Chinese Monal? --Ginkgo100 ^{talk · e@} 21:28, 29 August 2006 (UTC)

Peacocks? Just a wildfowl guess 9-)--Light current 21:51, 29 August 2006 (UTC)

No, I doubt it. The source (from a reliable local historian) went on to say the pheasants populated the eastern plains of Colorado and are enjoyed by hunters, and I know for a fact there are no wild peacocks hunted on the plains of Colorado! --Ginkgo100 ^{talk · e@} 22:35, 29 August 2006 (UTC)

Golden pheasants says they are chinese pheasants and the picture at Golden pheasant looks like what I have heard called chinese pheasant. If you search for them on google you find that they are good with onions. MeltBanana 01:07, 30 August 2006 (UTC)

LOL: I kept getting that same link about the onion recipe, which is why I gave up on Google! Thank you for finding the information; I bow to your superior Wikipedia-searching skills. I'll create appropriate redirects now. --Ginkgo100 ^{talk · e@} 20:38, 30 August 2006 (UTC)

Space

Can space exist on its own, or do you need mass to create it?--Light current 22:11, 29 August 2006 (UTC)

lol, space can exist on its own. Mass does not create it, it can only affect it. — [Mac Davis] (talk) (Desk|Help me improve)

Are you sure?? How would you define space? Is it something or nothing?--Light current 23:51, 29 August 2006 (UTC)

Mass needs space, otherwise there'd be nowhere for matter to fit. JackofOz 00:37, 30 August 2006 (UTC)

No! Space needs mass to exist!--Light current 03:14, 30 August 2006 (UTC)

If you're so sure of this, why did you ask your original question? JackofOz 04:41, 30 August 2006 (UTC)

It seems obvious to me now that since you cannot truly escape the bounds of the known universe, you cannot actually get into real space. THis needs moving to talk:space --Light current 11:29, 30 August 2006 (UTC)

No-one knows. But space does have geometry and energy. Now, if we had an extra universe and we took all the mass out... Peter Grey 03:56, 30 August 2006 (UTC)

Your question kind of relates to mine: is a universe without mass or energy really a universe at all, or is it just nothingness, a non-universe, what surrounds this tiny expanding region of matter and energy to infinite depths into the beyond.. --Froth 02:50, 30 August 2006 (UTC)

Its less than nothing. it doesnt exist!--Light current 03:14, 30 August 2006 (UTC)

In quantum field theory the vacuum has energy, and therefore mass. --Lambiam^Talk 05:09, 30 August 2006 (UTC)

Lets ask another question: Is it possible to accelerate your space craft beyond the limits of the universe?--Light current 03:19, 30 August 2006 (UTC)

If that was possible, they wouldn't be truly the limits, would they? --Lambiam^Talk 05:09, 30 August 2006 (UTC)

There isnt even a vacuum. This discussion should be moved to talk:space--Light current 11:29, 30 August 2006 (UTC)

You mean the ZPE field? — [Mac Davis] (talk) (Desk|Help me improve)

There is a vaccum in my closet.. --Froth 14:33, 31 August 2006 (UTC)

THe question is whether you can have ZPE somewhere where ther is no mass around at all. Anyway this discussion should not be here now and I have copied it to talk:space . Pls resume any discussion thers. Thanks

Global warming

Do Americans believe that global warming is occuring and if so why do you believe it is occuring? In the UK we are constantly presented with the idea that you USAers think that global fossil fuel consumption and industrial pollutants do not directly contribute to atmospheric pollution. Instead we are are told that the US does not believe that pollutants directly contribute to the greenhouse effect but that is an aspect of natural climatic change and that our opinon is incorrect. I have seen many Americans on the telly who believe that climatic change is as a result of our use of fossil fuels and industrial processes, but we are constantly lead to believe that the administration does not want to affect change becase of dubious scientific evidence linking them. --russ 22:27, 29 August 2006 (UTC)

I wouldn't be surprised if Bush and friends don't believe in global warming. I wouldn't lump every American him. --liquidGhoul 22:52, 29 August 2006 (UTC)

Most people around the world I think believe in anthropogenic global warming hypothesis. However when a real scienfic discussion arises there can be debate between sketpics and "global warmers"/believers. — [Mac Davis] (talk) (Desk|Help me improve)

I think most Americans and the Bush admin believe in global warming. The admin, however, chooses to suppress the science in order to protect the powerful oil industry, in which they have a personal financial interest. StuRat 23:29, 29 August 2006 (UTC)

That is probably why, although I think it should be noted many aspects of the anthropogenic hypothesis are disputed. — [Mac Davis] (talk) (Desk|Help me improve)

I don't think many serious scientists dispute that carbon emissions are affecting global warming (only those paid off by the oil industry directly, or indirectly via the Bush admin). Exactly how much of global warming is due to carbon emissions, however, is a subject of lively scientific debate. StuRat 05:02, 30 August 2006 (UTC)

According to this, about 1/2 of Americans are concerned about global warming versus 2/3 of UK citizens. Dragons flight 00:10, 30 August 2006 (UTC)

You might ask User:Ed Poor on the subject. User:Zoe|(talk) 01:46, 30 August 2006 (UTC)

Bush says global warming is not based on good science. Many of his fundamentalist followers also do not believe in evolution and think nothing is older than about 6000 years. Edison 03:55, 30 August 2006 (UTC)

Its the sun that causes global warming. Always has been. Always will be!--Light current 03:56, 30 August 2006 (UTC)

Right. And by increasing our burning of fossil fuels, we will block more sunlight due to more particulates in the atmosphere, thereby blocking more of the sun. See? Bush really does believe in, and is working to reduce, global warning! Hmm...guess I better clean this up and submit a manuscript to Ann. Improb. Res DMacks 04:30, 30 August 2006 (UTC)

Don't omit from your manuscript the plan to bomb as many sandy, dusty countries as possible, in order to produce fine silica particulates. this is an international program, with assistance from great britain, israel, hamas, hizbollah... Xcomradex 05:02, 30 August 2006 (UTC)

Is this a Bush-joke section of the desk? Global dimming was something that some scientists were concerned about not long ago. — [Mac Davis] (talk) (Desk|Help me improve)

we all know the real cause: http://uncyclopedia.org/wiki/Global_Warming#Causes Xcomradex 06:29, 30 August 2006 (UTC)

No, no, it's the terrorists who cause global warming. During the days after 11-9 all planes were grounded in the US. As a result there were fewer clouds, resulting in more sunshine and hence more warming. So there you go! :) DirkvdM 09:27, 30 August 2006 (UTC)

I heard that too. Its a very complex subject indeed.--Light current 14:40, 31 August 2006 (UTC)

August 30

Bouncing babies...?

Hello All!

I just heard that "dandling" or bouncing a baby upon one's knee can cause great damage, as the child's brain will wiggle about...? This sounds a bit off to me, and I haven't the least idea were I would find out whether or not this is true. Any help would be very much appreciated! Russia Moore 01:52, 30 August 2006 (UTC)

See shaken baby syndrome. --Kainaw ^(talk) 02:03, 30 August 2006 (UTC)

Obviously a an overly vigorous bounce could casue damage, so just use some common sense and don't go nuts with the baby. It makes a difference here too what age of baby we are talking about. If they aren't old enough to have developed the muscles that support the head, then you should be supporting the head no matter what you do. Older babies are different, but again, the amount of force is the issue. pschemp | talk 02:08, 30 August 2006 (UTC)

Just bounce him/her carefully. it nver dud mu ayn dmagew (apart from the slight spelling problem 8-)--Light current 02:28, 30 August 2006 (UTC)

Thanks so much, I should have thought of shaken baby syndrome (I was just reading about child abuse cases today)! Of course I assumed that most people have the common sense not to vigorously shake an infant, but sadly I suppose this is not the case. Anyhow, my baby brother never seemed to suffer from playing horsey... But now when I next get ahold of a bouncable baby I will be able to rest my mind that I am not dashing parental hopes of Ivy Leagues :P -Russia Moore 02:43, 30 August 2006 (UTC)

I think its the acceleration or shock you have to watch.--Light current 02:46, 30 August 2006 (UTC)

When I read of "shaken baby " syndrome I picture some foolish and/or evil caregiver or parent grabbing the baby by the shoulders and shaking it to and from them because they are angry it is crying, so its head flops back and forth from the chest to the back, causing impacts of the brain against the skull. I do not picture someone bouncing the little one on the knee to a tune. Edison 03:58, 30 August 2006 (UTC)

Yes but read my previious post!--Light current 04:02, 30 August 2006 (UTC)

Russia, out of curiosity, did you hear that from the comment in the A.Word.A.Day mailing list? —Daniel (‽) 11:15, 30 August 2006 (UTC)

I did indeed :) Russia Moore 02:38, 31 August 2006 (UTC)

Yay. —Daniel (‽) 08:37, 31 August 2006 (UTC)

Noise Cancelling Within Commercial Aircraft

I recall being told that a low fequency sound is transmitted in commercial aircraft to cancel the noise of, for example, crying babies. I don't mean noise cancelling headphones (as referred to in a question above) but a sound that is transmitted throughout the whole passenger area.

Does this exist?Downunda 03:42, 30 August 2006 (UTC)

I think you may be thinking of the masking effect of white noise--Light current 03:58, 30 August 2006 (UTC)

You might go for pink noise as well. I'm not sure I would refer to any of them as being low frequency, though. —Bromskloss 08:23, 30 August 2006 (UTC)

Noise similar to that from air handling equipment is sometimes used in offices to mask audibility of speech. Otherwise, in an open plan office, one might hear conversations 50 feet away or more. Sometimes a new installation of masking noise is made over a weekend or holiday. If it is initially turned up too loud, workers may call the janitor to complain of a toilet running without shutting off. Edison 04:01, 30 August 2006 (UTC)

If thats a swishing noise you describe, its white noise.--Light current 04:04, 30 August 2006 (UTC)

Or pink noise. Ok, mabye white noise is swish and pink noise more like swosh. Listen for yourselves: white pink I think I've hear about pink noise being used for precisely this masking purpose. —Bromskloss 19:44, 30 August 2006 (UTC)

induced gravitational effects

• in the presence of a magnetic field, charge tends to orbit

• if charge is constrained to orbit, magnetic field effects are manifested

• in the presence of mass, light is deflected (tends to orbit)

Q: is it the case that if light is constrained to orbit, gravitational effects will manifest? [say, coherent light in a fibre-optic coil, geometry such that the content of adjacent loops are in phase] 05:00, 30 August 2006 (UTC) 71.113.160.42

You may be looking for someting like geon? — [Mac Davis] (talk) (Desk|Help me improve)

It's an interesting theory. Nothing in the current understanding of physics predicts such an effect, but we know that we have been unable to combine general relativity and quantum electrodynamics in a coherent fashion, so why not? --Lambiam^Talk 05:23, 30 August 2006 (UTC)

If light is constrained to 'orbit' no light can escape because its velocity is less than the escape velocity. This sounds like a black hole--Light current 11:34, 30 August 2006 (UTC)

Perhaps the stellar object is surrounded in a cloud of Bose–Einstein condensate?  freshofftheufoΓΛĿЌ  14:22, 30 August 2006 (UTC)

I agree with Lambiam that it's an interesting theory, but as the old saying goes, "There is nothing new under the sun". In fact, at several talks given by Dr Karl Kruszelnicki, he has shown footage of an experiment he took part in that sounds like practically the same idea - by forcing light to travel in a tight orbit (I forget the details of how), they were hoping to observe some relativistic-style effects. Unfortunately, any effects that may have been present were too small for their apparatus to detect, and if their theory had worked there should have been some damn impressive results. Confusing Manifestation 14:03, 30 August 2006 (UTC)

What does benzoxycamphor mean?

ATTENTION: The REAL longest word in the English language is triskaidekaphobia, meaning fear of the number 13. =)

At Longest word in English benzoxycamphors is said to be potentially the highest-scoring word in Scrabble. Web searches don't reveal any more than it being a chemical compound. I wonder if someone could explain what sort of chemical it is, and where it might be found and/or used. Thanks. KeithD 06:43, 30 August 2006 (UTC)

• Perhaps you mean benzyloxycamphor? – ClockworkSoul 06:58, 30 August 2006 (UTC)

I do mean benzoxycamphor, as at [6], simply because benzyloxycamphors wouldn't fit on a Scrabble board. Could benzoxy... be another name for benzyloxy...? KeithD 07:32, 30 August 2006 (UTC)

conceivably, compounds are called all sorts of things under the old system. i'd be surprised if it was a legal word however for the purposes of scrabble. Xcomradex 08:38, 30 August 2006 (UTC)

For what it's worth, pharmaceutical sedatives such as valium, xanax, rivotril, and ativan all fall into the pharmaceutical category of benzodiazepines. I'd suspect that the chemical you're speaking of is somehow related. Loomis 11:17, 3 September 2006 (UTC)

They're not related at all. Camphor is a terpenoid, better known as a moth repellent. "Benzoxycamphor" doesn't really make sense as a chemical name, but it could be a (badly named) derivative of camphor.Pikiwedian 07:21, 5 September 2006 (UTC)

Dense material

Hi. I'm looking for an element/alloy as dense as possible, as cheap as possible and as malleable as possible (in order of descending importance) and without any other undesirable property, such as toxicity. I read the articles osmium and iridium but, while their density is excellent for my purpose, they are cost-prohibitive and, to make matters worse, osmium oxide is said to be very toxic. Any ideas? Thank you very much.

EDIT: OK. The idea is to have weights in the ankles to increase leg strength while running, but they are normally made of a substance which causes the weights be too bulky and uncomfortable, and at the same time, they weigh too little.

If you tell us what you want to do with it, someone may be able to suggest the best thing. --liquidGhoul 11:09, 30 August 2006 (UTC)

Lead would probably be the normal choice for this, although it is toxic if ingested. Just encase the lead in plastic to solve that issue. StuRat 11:22, 30 August 2006 (UTC)

Depleted uranium? 8-). Otherwise brown lead.--Light current 11:37, 30 August 2006 (UTC)

Maybe a better idea would be to put chewing gum on the soles of your shoes. THat would slow you down! OR.. you could try running thro water-- thats hard! OR long grass etc!--Light current 12:03, 30 August 2006 (UTC)

I second the vote for lead. You could encase it in rubber very easily with that stuff that you can get at hardware stores for dipping the handles of tools into to give them a rubber grip. Dismas|^(talk) 13:55, 30 August 2006 (UTC)

Not helping, but I wouldn't be surprised if (or I'm pretty sure that) those ankle weights are usually filled with lead in the first place.  freshofftheufoΓΛĿЌ  14:13, 30 August 2006 (UTC)

You didn't ask for this but I'm giving it to you anyway. Ankle weights are not the best way to gain leg strength; in fact, for the amount of torque they put on your knees, it's really really really not worth it. Just go to the gym. Weight training is a very good compliment to aerobic exercise. Anchoress 15:45, 30 August 2006 (UTC)

Or wading thro water. OR the simplest of them all-- cycling--Light current 16:11, 30 August 2006 (UTC)

Your best bet to accomplish what you are looking for is running up slopes or setting a high incline angle on a treadmill.--JLdesAlpins 16:56, 30 August 2006 (UTC)

Or cycling uphill.--Light current 16:59, 30 August 2006 (UTC)

On a treadmill, perhaps. In any case, I can see you're into cycling. :-) —Bromskloss 19:37, 30 August 2006 (UTC)

For some reason, no one's mentioned this yet (enough (Anchoress)). If the masses are more than 1.5kg per leg, you risk serious ligament damage to the knees. You might think that a leg weighs a good 20kg or so, so what difference is 2kg gonna make? But, a leg's weight is distributed with most of it at the top (thigh), so adding 2kg to the feet is very unbalanced. The problem arises in that the knee is designed to take mainly compressive loads, and the artificial mass you've added is pulling down on the knee joint, not the way it's supposed to. Just a heads up. ≈Eh-Steve 18:06, 30 August 2006 (UTC)

Thank you very much for all your responses.

Algae

Can algae utilize amino acids from their culture medium? I mean specifically can they use the amino acid directly to build protein, without first breaking the amino acid down, the way an animal can. (I am specifically interested in the species schizochytrium limacinum)ike9898 14:12, 30 August 2006 (UTC)

Algae are not consumers, and hence have no mechanism for which to absorb the amino acid into their cell. --liquidGhoul 14:21, 30 August 2006 (UTC)

Are you sure? Some artifical algae culture media includes peptone. ike9898 14:28, 30 August 2006 (UTC)

I see the problem here, Schizochytrium limacinum is a protist which either acts as a decomposer, or a parasite to algae. Check out Labyrinthulomycetes, it has Schizochytrium in the list of genera. --liquidGhoul 14:55, 30 August 2006 (UTC)

Body fat and menstruation

What is the minimum body fat percentage needed for a woman to menstruate? I looked in body fat percentage and menstrual cycle and even amenorrhoea, but couldn't find that particular piece of information. CameoAppearance 15:22, 30 August 2006 (UTC)

This link here references a 1981 JAMA article showing that less than 17% body fat is associated with amenorrhea. It sounds like there is more to the story than just that (ie genetic factors) InvictaHOG 15:51, 30 August 2006 (UTC)

I don't know if there is an absolute cut-off for minimum body fat in order for menstruation to occur. For instance, exercise-induced amenorrhea may have something to do with the loss of diurnal variation in leptin as a woman loses weight, and also with relative caloric deficiency due to inadequate nutritional intake for the amount of energy expended. Rather than body fat percentage, studies often use body mass index. See also this study - Cybergoth 16:01, 30 August 2006 (UTC)

Some quotes gleaned from various sources:

• "Some become amenorrheia at 18 percent, others at 16 or 14 percent," Lohman [director of the body-composition lab at the University of Arizona College of Medicine Department of Physiology in Tucson] says.
• Why, given a group of women with similar exercise programs and low percentages of body fat, do some experience menstrual problems and others do not? The answer usually relates to nutrition. Women with amenorrhea may be striving to maintain a weight lower than appropriate for their genetics. When the cost of achieving this desired leanness is inadequate nutrition, menstruation will cease.
• Amenorrhea is the clinical term for cessation of menstrual periods with possible related loss of ovulation. This is generally seen in women who train very heavily and/or have bodyfat below 12-15%; [...] However, research has demonstrated that amenorrhea is not caused by low bodyfat per se. Rather, it appears to be triggered by a long-term negative energy balance, which can result in a low bodyfat.
• There seem to be many factors which contribute to menstrual disturbance in female athletes. [...] In the early 70s two scientists suggested that a body fat percentage of 17 percent is required for menstruation to begin and 22 percent is needed for menstruation to be maintained. [...] However, this is not the complete answer. Some ballet dancers and swimmers who develop menstrual irregularities when training become more regular when they are not training, even though their body weight does not change. Some amenorrhoeic runners are of normal weight and other studies have found no difference in height, weight or percentage body fat between amenorrhoeic and menstrually-regular runners. [...] There does seem to be a direct relationship between the training load and the degree of menstrual irregularity, at least in runners. One study found a direct relationship between distance run per week and the incidence of menstrual irregularities, although an exact threshold above which menstrual irregularities start to occur has not been found.

It appears that there is no easy answer. --Lambiam^Talk 16:01, 30 August 2006 (UTC)

tetrachlorodibenzo-para-dioxin (TCDD) and Thyroid disease

The EPA and the National Academy of Science do recognize that TCDD has some effect on endocrine receptors in humans. Just how and at what dose seems still to be a mystery. Looking for all the information I can get on this subject.

Looks like you've stumped Wikipedia! Rentwa 16:55, 1 September 2006 (UTC)

Mattresses

What benefits would evolving in the shape and density of a mattress have, and how might one evolve in such a way given survival of the fittest and all that? This is not a homework question.  freshofftheufoΓΛĿЌ  15:41, 30 August 2006 (UTC)

Possible sleep configuration of a nuclear mattress family, cave setting

Is this a The Hitchhiker's Guide to the Galaxy related question? I would assume that it would greatly depend on the environment the creature lives in, and the way that the surrounding organisms have evolved. There are probably countless ways that mattresses could evolve, including artificial selection. -- Consumed Crustacean (talk) 15:52, 30 August 2006 (UTC)

Can you clarify the question? Is this a question about the evolution of mattresses qua shape and density, or about the evolution of some species, such as Homo sapiens, into mattress-shaped lifeforms? --Lambiam^Talk

I don't see why it would be any more unreasonable to expect homo sapiens to become mattresses. It might even be easier that way, because, as you could probably guess, these mattresses can talk.  freshofftheufoΓΛĿЌ  17:14, 30 August 2006 (UTC)

Im gonna have to sleep on that one!--Light current 16:13, 30 August 2006 (UTC)

• groan* --Froth 14:36, 31 August 2006 (UTC)

Stackability would ensure efficient sleeping, transport, and sexual arrangements, sound absorbency would mean a quieter environment, crashes and jumping from a great height would rarely be fatal,...--Shantavira 17:44, 30 August 2006 (UTC)

Yes! Stackability, now that would be useful. I can imagine scenarios where a creature would give up their ability to walk instead gaining the ability to bound short distances, most of them being in extremely docile environments where food supply is always guaranteed.  freshofftheufoΓΛĿЌ  05:58, 31 August 2006 (UTC)::

Over active thyroid

Is it possible to:

• Be thin as a rake (ie BMI = 18)
• Not sleep well
• Have very fine hair (someties falling)
• Have Very smooth skin
• Always be 'on the go'
• Have limited attention span (scatter brained)

and not have an over active thyroid?--Light current 17:21, 30 August 2006 (UTC)

Since you're using an AND logical construction, all of the conditions must evaluate to YES in order for the function to also result in YES. Since it is not possible to be as thin as a rake (even the skinniest humans easily eclipse common rakes), I can therefore safetly conclude that the answer to your question is no.  freshofftheufoΓΛĿЌ  17:34, 30 August 2006 (UTC)

OTOH, from the principle of explosion, anything follows from a contradiction. If a person is thin as a rake, we have a contradiction, because you showed that they're not. So, anything follows. Even thyroids on steroids. —Bromskloss 19:33, 30 August 2006 (UTC)

Depends on thet size of your rake dont it? 8-) OK If you have all the above conditions, can you stil NOT have an over active thyroid?--Light current 18:13, 30 August 2006 (UTC)

Did you try to create that userbox "This user wants to be convinced that (s)he has an over active thyroid", with a nice picture of one ? -- DLL ^{.. T} 18:41, 30 August 2006 (UTC)

I know not of what you speak, dear sir!--Light current 18:43, 30 August 2006 (UTC)

Add in the other common symptoms like high appetite, diarrhea, headaches, and high libido and you are closer to describing a textbook case of hyperthyroidism, not that you should ever be using wikipedia to fetch medical advice... To more directly answer your question, see Amphetamine or UBS Guy for a possible alternate explanation --Jmeden2000 20:41, 30 August 2006 (UTC)

Ah well, she aint got diarrea, headaches, and is as cold as a fish! How now? Should I be telling her to go to the doctor TITQ--Light current 20:46, 30 August 2006 (UTC) Oh yeah I forgot to say she has good appetite but somtimes misses meals cos shes so busy running round.--Light current 21:41, 30 August 2006 (UTC)

If you think the factors are abnormal then a visit to the doctor would be in order. Consider that you may be projecting hypochondria, not that I am qualified to make that diagnosis (perhaps i am a vicarious psychoanalyst but again this is no place for medical advice). --Jmeden2000 21:00, 30 August 2006 (UTC)

It is certainly possible to have those symptoms and not have hyperthyroidism. However, those symptoms should certainly prompt thyroid testing, as they are commonly associated with an overactive thyroid. InvictaHOG 21:05, 30 August 2006 (UTC)

What do I say to try to get her to go? Shes quite strong willed and may resent me suggesting she is not completely fit. She says shes always been v thin and her brother is the same. Could he have it too?--Light current 21:13, 30 August 2006 (UTC)

If she doesn't want to listen to you, she won't. Just give it your best try. If she's going to the doctor anyway, it's just a simple blood test. InvictaHOG 01:07, 31 August 2006 (UTC)

THanks to all for the replies!--Light current 01:11, 31 August 2006 (UTC)

Intelligence

Does editing WP make you more intelligent? If so, how long does it take to work/ 8-?--Light current 18:55, 30 August 2006 (UTC)

Yes, of course. Within a month of editing at Wikipedia you will have amassed a lifetime of knowledge about exploding whales, masturbating pigeons and how to suitly emphazi a question. There are plans to release a pill which will contain all this information and transmit it into the brain of the taker, which will render all your gains obsolete soon though. —Daniel (‽) 18:47, 30 August 2006 (UTC)

WP won't be of much help if you can't even remember to sign your posts.  ;-) --hydnjo talk 18:50, 30 August 2006 (UTC)

Sorry--Light current 18:55, 30 August 2006 (UTC)

See, you're getting smarter already. 9-) --hydnjo talk 19:17, 30 August 2006 (UTC)

Why is your writing so small?--Light current 19:23, 30 August 2006 (UTC)

Because I'm writing quietly. --hydnjo talk 19:34, 30 August 2006 (UTC)

Why are you writing quitely?--Light current 19:36, 30 August 2006 (UTC)

So as to not call much attention to some of my posts, but It doesn't always work. --hydnjo talk 19:43, 30 August 2006 (UTC)

WRITING BIGLY WORKS BETTER TO DIVERT ATTENTION AWAY FROM YOURSELF. — [Mac Davis] (talk) (Desk|Help me improve)

Umm, more like a device to give the impression of a footnote or a parenthetical. --hydnjo talk 20:02, 30 August 2006 (UTC)

Er.. yes?--Light current 20:30, 30 August 2006 (UTC)
...er..umm... yes, excactly. --hydnjo talk 21:14, 30 August 2006 (UTC)

Not to be a pain, but...please don't use the reference desk as a chat room. How about using your talk page? ike9898 21:23, 30 August 2006 (UTC)

Im not using it as a chat room. We may be digressing somewhat-- thats all.--Light current 21:26, 30 August 2006 (UTC)
And I certainly have no intention of sharing a room with Lc. --hydnjo talk 21:58, 30 August 2006 (UTC)

In all seriousness... using your brain in any intellectual pursuit, from doing logic puzzles to writing research papers, improves your thinking ability. Editing Wikipedia surely qualifies as the latter ... or at least it should, if you're doing it right. --Ginkgo100 ^{talk · e@} 20:33, 30 August 2006 (UTC)

• Intelligence and knowledge are two different things, but yes doing stuff that challenges your brain like reading and editing Wikipedia is probably going to be benefitial for your IQ. - 131.211.210.11 07:50, 31 August 2006 (UTC)

My typing and grammar have gotten much better since I started Wikipedia (especially my typing, I couldn't touch type before and now I am quite proficient!). --liquidGhoul 12:32, 31 August 2006 (UTC)

creatine article

in the creatine article there is a statement that there are vegetarian sources of creatine. I have not been able to find out what those sources are so i would much appreciate further information on the subject.

205.56.129.194 19:28, 30 August 2006 (UTC)Smith

Vegetarian creatine can be obtained via chemical synthesis using plant-derived amino acids.--Light current 19:35, 30 August 2006 (UTC)

Asking a subject reference question

Aha! I think this is the feature I was looking for. Thank you!

...Do you have a question? --Ginkgo100 ^{talk · e@} 20:31, 30 August 2006 (UTC)

He/she was just seeing if they knew how to ask a question if they needed too. He/she thanked as for the future service we may do to him. We are, after all, "in the service." — [Mac Davis] (talk) (Desk|Help me improve)

You're welcome (to what I'm not sure, though). DirkvdM 08:44, 31 August 2006 (UTC)

Iran and Nuclear Power

Why does Iran want to build nuclear power plants when they have such a large oil reserv?165.139.186.7 20:03, 30 August 2006 (UTC)

I wonder!--Light current 20:32, 30 August 2006 (UTC)

For lots of information see Iranian nuclear program; their rationale is treated at Iranian nuclear program#The Iranian Point of View. Melchoir 21:10, 30 August 2006 (UTC)

They're afraid of global warming, which, disputably, will cause a drastic rise in the seagull bagel population. In the 147th passage of the Qu'ran, it states "Jihad shall be against the non-Islamic, and bagels." It is really a three-fold problem for them. The educated Islamofascist know that global warming will simultaneously cause a spike in bagel populations, Kill All Humans, and, because humans are much more productive when temperatures are hotter, the fucking infadels will have better technology. — [Mac Davis] (talk) (Desk|Help me improve)

why does the US want to build nuclear power plants, when they have such large oil reserves (not to mention bagels). Xcomradex 21:58, 30 August 2006 (UTC)

Both parts of your statement are completely wrong; the US does not have enough current oil production to meet it's own needs, an it's not currently building nuclear power plants (although perhaps it should be). StuRat 03:21, 31 August 2006 (UTC)

So they have more enriched uranium and plutonium than Iran (and prob everyone else put together) of course. 8-)--Light current 22:02, 30 August 2006 (UTC)

It's just a cover story so Iran can build nuclear weapons, even the normally gullible Europeans can see this. StuRat 22:05, 30 August 2006 (UTC)

Really? I would never have guessed that! 8-)--Light current 22:06, 30 August 2006 (UTC)

Probably, yes. But this is the science reference desk, and that is not a falsifiable hypothesis. Melchoir 22:18, 30 August 2006 (UTC)

There's a lot of people who think like StuRat (and on this rare occasion I do happen to at least partially agree with him) but the Iranians argue that a) they want to make sure their petroleum reserves last as long as possible, and b) those petroleum reserves are more valuable being sold than generating power domestically. See nuclear program of Iran. --Robert Merkel 22:25, 30 August 2006 (UTC)

After Pakistan said they weren't working on nuclear weapons, then completed one, then North Korea did the same, anyone who believes that Iran, a country which publicly calls for the destruction of Israel and publicly supports a terrorist organization trying to do just that (Hezbollah), just wants "peaceful" nuclear energy, is truly naive. StuRat 23:10, 30 August 2006 (UTC)

Also, try Iran's civilian nuclear program. Melchoir 22:35, 30 August 2006 (UTC)

I think that Iran's leaders are playing two games at once. One is the development of what is currently a nuclear program of dual-use technology—everything in their program ostesibly has a peaceful purpose, though all of it could also be diverted for a weapons program as well. This gives them a little room to claim that they are having their rights trampled on—according to the NPT, peaceful nuclear programs are allowed, though with some qualifications. The second game is related to the first; they get to be a leading voice in the region confronting the United States, claiming scientific progress, and using the entire incident as an opportunity to point out the double standard that the U.S. has towards Israel's nuclear weapons program. The Iranians also are fond of saying something very strong—i.e. that Israel should be wiped off the map—and then backing down from it with a more mild explanation—i.e. that they were only talking about it in defensive terms, and that they were just warning Israel not to attack them unprovoked. It puts them in an advantageous regional position, and I don't think its a coincidence that their hardliner president dresses in Western clothes and looks more like a Western politician than he does a Shiite cleric.

As for the oil reserves—I'm pretty sure even the most optimistic estimates point to a falling off of Middle Eastern oil reserves within the next two decades or so, which will put Iran and everyone else over there up a creek if they don't have fallback industries and energy production.

Are they making a bomb? Probably not at the moment, not as a full program anyway. They're hedging their bets for one though, trying to get just enough technology that they'll be able to work one up over time (the same way Pakistan did theirs, which took decades to make because they were content with doing it slowly). At the moment they are pursuing so many alternative routes—uranium, plutonium, etc.—that they could drop one of them from international pressure and still be able to pick up the slack in another area.

Most analysts don't think Iran could develop a bomb within the next decade, though. The real regional danger of Iran getting a bomb is less that they would use it against Israel, but would rather use it as a check against Israel using their own bomb against them, and then hope to beat Israel at conventional warfare, IMO. (My personal biggest fear at the moment is that Israel will, one way or another, get involved in a war with Iran as they are currently with Lebanon, and then drag the United States/United Nations in with it.) --Fastfission 23:37, 30 August 2006 (UTC)

It's true, Iran has an enormous army with an enormous number of personnel and likely a pretty hefty cache of land artillery. Yet its air force and navy are practically non-existant. With the possible exception of some long-range conventional missiles, how could Iran possibly conduct any sort of conventional warfare against Israel? How would they even get there? Would several hundred thousand Iranian troops be zipping through a couple of thousand miles of desert, through US occuppied Iraq and then Jordan on dune buggies? Loomis 01:26, 1 September 2006 (UTC)

Any claim Iran makes to only want a peaceful nuclear program was shown to be false by their rejection of Russia's offer to provide nuclear fuel and get the spent fuel back. This would provide Iran with all the nuclear power they wanted, but deny them the possibility of enriching the fuel further for use in nuclear weapons. Therefore, Iran rejected the offer. StuRat 23:45, 30 August 2006 (UTC)

Yes, because Iran's experience with OPEC has taught it that building an energy infrastructure around a foreign source of fuel is such a good idea. Melchoir 23:57, 30 August 2006 (UTC)

I don't think a single rejection of a plan can be used as a convincing case, especially when it is a plan that forces them to basically be at the diplomatic mercy of another country. (And it is not like Russia has not used denial of resources before as a way to throw around weight, i.e. by denying oil to Ukraine and things like that.) If I were a president of a country like Iran, I wouldn't be too eager to have my nuclear program be completely at the mercy of the Russians. I think it is more convincing that Iran has continually sought dual-use technology even when there have been options otherwise, and that they have so far been resistant on safeguards. --Fastfission 00:32, 31 August 2006 (UTC)

Unlike OPEC's oil, even if Russia stopped supplying nuclear fuel, it would be years before Iran's current nuclear fuel supply would be spent, giving them plenty of time to switch to another supplier or back to oil. Therefore, any Russian threats to cut their supply would be highly ineffective. StuRat 03:18, 31 August 2006 (UTC)

the US's opinion back during the days of the Shah was iran would need five nuclear power plants by 1994 (number from memory), and they even helped arrange a consortium with germany and france to build said powerplants. yet fast forward a few years and look what happens. Xcomradex 02:07, 31 August 2006 (UTC)

Ahh, but the Shah was America's friend! (Not the peoples friend)--Light current 03:13, 31 August 2006 (UTC)

One should never put all of one's eggs in one basket. As was indicated before one can ask a similar question of many other countries (and also why they would need or have more right to nuclear weapons, for that matter). The Netherlands has the biggest gas bubble in the world. So what do we need nuclear plants for? A better question might be why they don't focus on solar energy, considering their climatic situation. Or do they? I don't know. DirkvdM 08:58, 31 August 2006 (UTC)

To offer a Canadian perspective, just as Iran's oil reserves may some day run out, necessitating the need for nuclear power, up here we fear that global warming will eventually eliminate all the snow from falling, thus destroying an extremely important aspect of our tourism industry, alpine skiing. Yes it's true, we fear that one day Canada will face a shortage of snow. With that in mind we're currently working on a snow making machine, using technology which, completely coincidentally, can be used to create a weapon that can destroy the evil American regime which should be wiped off the face of the map. Not to worry though, global warming is real, and we truly believe that such a machine will be necessary once all of Canada's snow has melted away and no more will continue to fall. Oh, and by the way, death to America. Peace y'all! Loomis 09:03, 31 August 2006 (UTC)

That's why nobody ever asks for a Canadian's perspective.  freshofftheufoΓΛĿЌ  12:14, 31 August 2006 (UTC)

Ouch! Why's that? Because nobody can handle the truth? Loomis 00:38, 1 September 2006 (UTC)

I agree that the question should be "with all the possible forms of energy available to Iran, why do they insist on the one form that also allows them to develop nuclear weapons, and reject any method that would allow them to develop peaceful nuclear power, but prevent them from developing nuclear weapons ?" Hmmm ... I just can't figure it out. StuRat 13:03, 31 August 2006 (UTC)

I'm just as confused as you are Stu. What do you suggest should be done? I say we force Iran to allow UN observers complete access to every nuclear power plant in Iran. That way, we'll all be safe in the knowledge that Iran won't be building nuclear weapons under all of our noses. That way, we'll be safe in the knowledge that Iran will only be building nuclear weapons openly and honestly under strict UN supervision. Loomis 01:06, 1 September 2006 (UTC)

The only possible solution I see is a military action, most likely taken by Israel, with US covert support. The UN will first put some weak, thoroughly useless sanctions on Iran, and will violate even those. This will have absolutely no effect on Iran. Then, when it is clear that Iran has nearly completed it's nuclear weapons, the only option left will be military action. I suspect the sites will be bombed with "bunker-buster" bombs (possibly low yield, tunneling nukes). It's too bad we don't have an effective UN that could actually take the actions necessary to get Iran to stop peacefully. That would take total sanctions on Iran, sealing all of the borders. The weakness of the UN makes war inevitable. StuRat 10:47, 1 September 2006 (UTC)

If all countries with nuclear plants would allow that (do any now?) and Iran would still not agree to it, then they would look pretty suspicious. It's mind boggling how often people find it perfectly normal to do unto others what they would never allow those others to do unto themselves. DirkvdM 09:04, 1 September 2006 (UTC)

Under your theory, since police have guns, we must provide all criminals with guns, as well, so we treat everybody equally. I would expect the US would agree to UN inspectors of their nuclear reactors, if that would get Iran to do so. However, inspecting US nuclear plants would be a complete waste of time, as the US already has more nuclear weapons than it knows what to do with. StuRat 10:33, 1 September 2006 (UTC)

I skipped that last bit to avoid complicating matters too much, but thank you fro bringing it up. You ma now attempt an answer to that hypocricy as well. :)

The police (and the army if needs be, but that never comes up domestically) should have a "monopoly on violence" as we say in Dutch. Translate this to international affairs. Who is to be the police? One specific country or a group of coutries or a joint effort of all countries in the world? Suppose the separate states in the US were different countries (not too far from the truth). What if California, in alliance with the rest of the West Coast would claim a right to all nuclear facilities and weapons and would invade other states if they had any plans of developing their own technology (or economic system, or whatever)? DirkvdM 13:04, 1 September 2006 (UTC)

OK, I can answer your silly scenario. Let's now say that Pennsylvania is dedicated to the total destruction of Virginia, says so publicly, and supports various terrorist organizations that launch missiles into Virginia, send suicide bombers into Virginia, and stockpile weapons in West Virginia, on the border with Virginia. Let's also say their terrorist organization is destabilizing West Virginia and causing destruction to it's infrastructure by Virginians trying to defend themselves from these constant attacks. Now Pennsylvania is claiming they need nuclear power, despite huge oil and gas reserves. They have rejected any attempt to monitor their nuclear plants to be sure they aren't building nuclear weapons and have been caught numerous times cheating on the nuclear nonproliferation treaty. Now, under these circumstances, absolutely, those states with nuclear weapons should all work together to prevent Pennsylvania from ever getting them. Hopefully, responsible states without nuclear weapons will also join in. If nothing else works, Pennsylvania should then be attacked, before it gets nuclear weapons. StuRat 06:12, 2 September 2006 (UTC)

But the US already have nuclear weapons, so are you saying we're too late with the invasion? Or weren't you talking about the US? DirkvdM 09:03, 2 September 2006 (UTC)

The word is "has". If there were aliens who could keep everyone from getting nuclear weapons, including the US, then that would be a good thing. However, as none seem willing to help us out that way, the next best thing is for as few countries as possible to have them; ideally only the "good" countries (which won't just use them to kill off or enslave everyone else in the world, as the Nazis, imperial Japanese, or Soviets would have, had each been the only country with nukes). StuRat 01:23, 3 September 2006 (UTC)

I don't see why the whole thing has to be turned pro or anti-US. Putting aside the US for now, there are still quite a few countries around the world that are stable and (relatively!) sane enough that no one worries whether or not they possess nuclear capabilities. Check out the list of countries with nuclear weapons. The Brits have the bomb, and that doesn't concern me one bit. The French...well despite being French and all, I'm not at all worried about their nukes either. As for Russia and China, though they may be misfit states, they still seem to be sane and practical enough to me (and have the track record to prove it) that they have no intention of launching an unprovoked nuclear strike on anyone. As for India and Pakistan, their main beef is with each other. Both being secular, the old Mutual Assured Destruction (MAD) principle would seem to take nuclear war out of the picture. And of course there's the Israelis, love'em or hate'em, whatever nukes they may have might just as well be harmless drones, built entirely for deterrent effect. I just can't see Israel ever using them, ever, even as a second strike. It just doesn't jive with the Israeli psyche.

The article also points out that countries like Canada, the Netherelands, Australia etc...(I picked those totally at random :) have all the technology necessary to build a bomb in a matter of weeks, but that doesn't concern me either. These countries are, (at least for the most part!) sane and pacifist, and see no use in possessing nuclear weapons, and rightly so, nobody seems at all concerned with whatever technological capabilities they possess.

But then you come across countries like Iran and North Korea. I'll leave North Korea aside for now. In the case of Iran though, the old MAD principle actually doesn't seem to apply. Even the Soviets weren't insane enough to launch a first strike, because to do so would risk an equally devastating reply from the US. Iran, on the other hand, is a different story. With its shahidist mentality, MAD would actually seem to have no application. "Nuke the Zionists and who cares if they nuke us back? We'll all go to heaven and they'll all go to hell". Now THAT scares the shit out of me. People speak of "double standards"...well I'd say there's a pretty solid logical basis for these "double standards". Loomis 14:29, 1 September 2006 (UTC)

Well said. Just as sane, responsible gun owners are OK, but giving guns to insane criminals is very bad, so would giving nukes to Iran be a very bad thing. For example, I would not be opposed to Japan getting nuclear weapons, as I only see them being used to prevent an attack by North Korea. StuRat 05:59, 2 September 2006 (UTC)

Most distant spacecraft visible from Earth

I have two questions:

1. What is the most distant spacecraft visible to telescopes on Earth? 2. What is the brightest spacecraft not in orbit around the Earth, and how bright is it?

--Bowlhover 21:41, 30 August 2006 (UTC)

The brightest not-in-orbit spacecraft would probably be something very close, maybe New Horizons, launched in January and by my calculations about 7 million miles away. The Wilkinson Microwave Anisotropy Probe is technically not in orbit around the Earth (it orbits the Sun-Earth L₂ point about 1.2 million miles away). I'm not certain if it ever comes out of the earth's umbra, but if it does, it's probably pretty dang bright. (Relatively speaking) -- Plutortalkcontribs 22:27, 30 August 2006 (UTC)

I thought about mentioning WMAP, and am likewise unsure of the umbra. On the other hand, SOHO is at the L1 point, and so is certainly in plenty of sunlight, but is also completely obscured by solar glare. If you don't like those, the current leader is likely SMART-1 orbiting the Moon, though it's about to crash. — Lomn | Talk 22:39, 30 August 2006 (UTC)

Well, Earth has an angular diameter of 0.24 degrees to the WMAP. The Sun has a diameter of 0.53 degrees, so our planet can't block more than 21% of the Sun's light. In other words, the WMAP is in sunlight. Anyone know how bright it is? --Bowlhover 05:21, 31 August 2006 (UTC)

Why can't we feel the mantle heat through the crust of the earth?

I have done a lot of research into plate tectonics and the geology of the earth on Wikipedia. I have learned a LOT, but I can't seem to find an answer to the following (basic) question anywhere:

If the mantle inside the earth is molten rock at 1200 to 2200 degrees (F), why doesn't any of that heat pass through the earth's crust (by convection) and reach the surface?

If there is THAT MUCH heat energy inside the earth, I would think that we should be able to experience at least SOME of it on the surface.

Thanks in advance!  :-)

Tim Barber (Harrisburg, PA)

We do! Ever heard of hot springs, volcanoes etc. THe miles and miles of rock forming the earths crust are a good insulator thankfully--Light current 22:09, 30 August 2006 (UTC)

Yes, rock is a good insulator, so any heat that the mantle delivers to the crust will be radiated away into space. It's like putting a block of wood on a stove--the wood (except for the part that touches the stove) won't feel hot. --Bowlhover 22:15, 30 August 2006 (UTC)

Also, the temp a few hundred feet underground is largely heat rising from the mantle. Only near the surface does heat from the Sun become dominant. StuRat 22:30, 30 August 2006 (UTC)

Yes for instance in some caves I recently visited, the temp is constant 12 deg celsius--Light current 22:34, 30 August 2006 (UTC)

We do feel it! If it weren't for the heat coming out through the crust from the interior of the Earth, the Earth surface where we live would be very much colder than it is. The heat is produced (mostly) by radioactive decay (and, by the way, goes through the crust by conduction, not convection). --mglg_(talk) 22:58, 31 August 2006 (UTC)

Correct, the heat gets to the crust by convection, then goes thru the crust by conduction (excluding geysers and lava spewing out of volcanoes). StuRat 10:28, 1 September 2006 (UTC)

I need to find critics to the socialist ideas.

thanks

Criticisms of socialism you say?--Light current 22:32, 30 August 2006 (UTC)

Do you mean finding the people themselves? —AySz88\^-^ 00:24, 31 August 2006 (UTC)

Not that you have any preconceptions of course. :) Ah, I get it, socialism makes so much sense that you can only think of pros and need others to make up the cons for you. :) DirkvdM 09:07, 1 September 2006 (UTC)

Question on the derivative market

Question on the derivative market and particularly on the process with several volatilities:

I would like to know if any process with more than one volatility for an underlying asset exist.

Nicolas

Economics homework? Its so easy with WP--Light current 00:27, 31 August 2006 (UTC)

Please do not double post. --Lambiam^Talk 02:44, 31 August 2006 (UTC)

Perpetual Motion

Is there anyone i can contact who is an expert in perpetual motion?

Nick Muller

Perpetual motion is a good read with some interesting external links. --hydnjo talk 23:57, 30 August 2006 (UTC)

If you want to take them at their word, the guys as Steorn would have you believe they are the best in the business. Rockpocket 05:19, 31 August 2006 (UTC)

But, if you read the long discussion below, they are mostly likely wrong. — QuantumEleven 07:41, 1 September 2006 (UTC)

Some call me an expert in my field, unfortunately though I stop every night to sleep. So I suppose I wouldn't qualify as an expert in perpetual motion. Loomis 04:29, 2 September 2006 (UTC)

August 31

Beef jerky

Can beef jerky, and jerky in general, be reconstituted, perhaps using broth? I'm sure it would be terrible, but is it even possible? Bhumiya (said/done) 01:48, 31 August 2006 (UTC)

I believe an MRE kit contains dehydrated meat to be soaked in water, with the idea being that the finished product will resemble actual meat. StuRat 02:06, 31 August 2006 (UTC)

Since its only dried meat, I dont see why it couldnt be reconstituted by heating in a pan (or uwave) with water. Yummy--Light current 02:07, 31 August 2006 (UTC)

Most dehydrated things can't be rehydrated to get the original back. A raisin soaked in water, for example, doesn't give you a grape, it give you a soggy raisin. StuRat 02:14, 31 August 2006 (UTC)

Thats just sour grapes on your part! 8-)--Light current 02:20, 31 August 2006 (UTC)

And if soggy raisins get you mad, then they would be The Grapes of Wrath. :-) StuRat 02:29, 31 August 2006 (UTC)

Actually I thought raisins were made from special sorts of grapes but the current thinking is that currants raisins and sultanas are all in fact dried grapes. I see no reason to doubt that.--Light current 02:36, 31 August 2006 (UTC)

Maybe you can reconstitute it, but I do not think you will get a properly functioning cow back. --Lambiam^Talk 02:49, 31 August 2006 (UTC)

Has any one noticed that the indentation is now rather pretty? shame I have to spoil it!--Light current 02:56, 31 August 2006 (UTC)

Not really, we can still go back and forth to keep up the pretty little indentation thing. As for the question, you know when people do weird stuff on tv and tell you "Please, by all means, DO NOT try this at home"? Well I don't think that would apply here. I can't see much harm resulting if you boiled a piece of beef jerkey and waited to see what happened. Keep us updated, the scientific community is relying on you for this one. Loomis 08:42, 31 August 2006 (UTC)

Yes I suggest the questioner try it at home!--Light current 11:04, 31 August 2006 (UTC)

You can reconstitute food to some degree. The water has gone from the cells and they won't function like perfect sponges, but you can get some water in there. Reconstituted jerky is usually mentioned as good for stews. I doubt you get a good filet mignon out of dried meat. Google for rehydrate jerky or reconstitute jerky. Weregerbil 11:33, 31 August 2006 (UTC)

physics andtehnology

59.93.32.70 02:28, 31 August 2006 (UTC)anees application of physics in other science disciplines ,or how physics theories applied in different science subjecs

ronlem unnerstanig qestiom ,please suitly emphazi Lambiam^Talk 02:51, 31 August 2006 (UTC)

I can work out most of the words, but what the hell is 'ronlem' supposed to be? Hang on I just saw it!--Light current 03:15, 31 August 2006 (UTC)

Body hair

Why do men have more body hair than women. Do women not feel the cold as much?--Light current 03:10, 31 August 2006 (UTC)

To differentiate the genders. (We have to make the trannies work a little bit, don't we ?) :-) StuRat 03:32, 31 August 2006 (UTC)

A trannie is a transistor radio! It was when I was young.--Light current 03:33, 31 August 2006 (UTC)

Well, I wouldn't suggest you go around telling people you enjoy fiddling with the knobs on your favorite trannies. :-) StuRat 03:37, 31 August 2006 (UTC)

Can I have an anthropological answer please?--Light current 03:33, 31 August 2006 (UTC)

I gave you one. It's so men and women can tell each other apart, which is rather critical to reproduction and survival of the species. StuRat 03:46, 31 August 2006 (UTC)

For sexual dimorphism. I restate the first answer. — [Mac Davis] (talk) (Desk|Help me improve)

What about monkeys? They can tell the diff, and theyre all hairy!--Light current 03:47, 31 August 2006 (UTC)

I suspect that the general reduction of hair in modern humans came as a result of clothing, making the thermal properties of hair optional, and thus a candidate for sexual dimorphism. Body hair isn't the only way we have to differentiate the genders, but the more obvious the genders are, the better for the species. StuRat 03:52, 31 August 2006 (UTC)

Possible. I would like more views please. BTW does that mean you couldnt recognise a woman if she was hairy all over? 8-) --Light current 04:03, 31 August 2006 (UTC)

The actual functional purpose of human body hair is no longer directly relevent as - most of us at least - wear clothes. Dimorphic body hair is a secondary sexual characteristic, that is, it is a result of the genetic/biochemical differences between men and woman. Specifically, increased levels of androgens in males promote the transformation of vellus hair to terminal hair in certain parts of the body. The reason some parts grow more than others is probably due to the androgen sensitivity in the local follicles. Rockpocket 05:17, 31 August 2006 (UTC)

Hey Light current we recognized you didn't we! Lemon martini 08:00, 31 August 2006 (UTC)

As what, may I ask?--Light current 11:44, 31 August 2006 (UTC)

Conjecturing that we have less body hair because of clothing is sort of backwards to me. We've been less-haired for quite some time, and it's more likely that clothing came about as a result to warm ourselves in contexts where thick body hair could've worked. Considering that modern humans evolved in Africa and there are other less-haired mammals (like elephants) in Africa, I'd say it was something related to the African climate that led to diminished body hair.

As far as sexual dimorphism, males are generally flashier than females, as with the peacock's tail feathers, the Betta's bright colors, the lion's mane, the colorful parts of the mandrill and the silverback's, well, silver back. Body hair dimorphism, as well as facial hair was probably used in very early times in a way similar to the attraction schemes of these other animals.

It's also possible that, since then, cultures have found hairless women to be more attractive thereby affecting selection pressures as well as shaving and waxing practices that make us think that women are significantly less hairy. AEuSoes1 08:38, 31 August 2006 (UTC)

Yes I think this last reply sums it up nicely for me. THanks for all suggestions--Light current 10:55, 31 August 2006 (UTC)

Something else to consider. While the environment can probably to be ruled out as a cause (there are lots of primates in Africa and we were the only near-naked ones), the answer of sexual dimorphism seems incomplete or incorrect to me. For one thing, different nationalities have different levels of body hair - sexual dimorphism doesn't explain why Japanese men and women are both pretty hairless, compared to some Mediterranean men and women. For another, if dimorphism was that strong a selector, I think we'd see much hairier men and much, well, smoother women across the board. I can see the argument for facial hair being a sexual signal, but body hair itself doesn't seem all that clear to me. Matt Deres 02:03, 1 September 2006 (UTC)

Enthalpy and heat

What is the difference between heat (q) and enthalpy (H)? Also, I don't understand fully what entropy is. I know the definition as the amount of disorder, but how would you measure it? Also, how does disorder relate to q/T? Thank you very much, you are great people.--216.164.200.120 04:48, 31 August 2006 (UTC)

Is this homework? Look at the links.--Light current 04:51, 31 August 2006 (UTC)

No this is not homework (and by the way, Light current, I've noticed you saying many questions are homework when they aren't), and I looked at the links, but they are somewhat confusing to me. Please could somebody help. --216.164.200.120 04:58, 31 August 2006 (UTC)

I just reread my question and noticed that it does look a lot like homework, however I assure you it is not as I do not start school again 'till September.

OK it just looked like it. How do you know the others are not homework if you didnt write them? Apologies if Im wrong. What is wrong with the article explanations?--Light current 05:05, 31 August 2006 (UTC)

H = E + PV \,

where E represents the energy of the system. In the absence of an external field, the enthalpy may be defined, as it is generally known, by:

H = U + PV \,

where (all units given in SI)

   * H is the enthalpy
   * U is the internal energy, (joule)
   * P is the pressure of the system, (pascal)
   * V is the volume, (cubic metre)

which bit is not clear?--Light current 05:10, 31 August 2006 (UTC)

I was told that q = E + PV also, which doesn't make sense. What does q really equal?

Then I also still have the question about how you measure entropy and how q/T is related to disorder. --216.164.200.120 05:17, 31 August 2006 (UTC)

• Entropy in chemical systems is relatively easily determined. The change in Gibbs free energy for a reaction, dG, can be calculated readily from reaction data, since dG = -RT ln(K). and given dG=dH - (T x dS), you can simply subtract the enthalpic component dH, and find the entropic component dS at a known temperature T. its that easy ;-) Xcomradex 06:50, 31 August 2006 (UTC)

Enthalpy is basically heat, entropy is basically disorder. Things tend to:

give out heat (like a hot cup of coffee - it gives out heat);

become more disordered (like my bedroom - it keeps getting untidier and more disordered).

Physical processes tend to occur if either of the above two things can happen. If a process does both then it will happen. If it does neither then it won't, and if it does one but not the other then it's a balancing act and the temperature will decide whether it happens or not (that's why part of the equation is multiplied by T).

Systems like to get rid of energy - they can do this by giving out heat or becoming more mixed up. If it seems difficult to accept that systems can lose energy by becoming more disordered (mixed up), think about it in reverse - to make my bedroom more ordered (tidier) I have to put energy into it when I go round clearing it up.

Enthalpy is easily measured experimentally and entropy is calculated from various results and equations. Don't worry about Q/T, it just comes from rearranging the equations. Rentwa 08:16, 31 August 2006 (UTC)

Thanks for that, Rentwa! Rentwa 15:24, 1 September 2006 (UTC)

Yeah! That's just about the best darn dummies guide to Thermodynamics I ever read! Rentwa 15:25, 1 September 2006 (UTC)

Yes, thanks. You are great people - Rentwa 15:26, 1 September 2006 (UTC)

Don't mention it, it was my pleasure! Rentwa 15:28, 1 September 2006 (UTC)

I'm going to award you the barnstar for wasting your time helping ungrateful &&*^%'s! Rentwa 15:31, 1 September 2006 (UTC)

Please don't bother, it was nothing! Anyway, I'd rather have a picture of a dog in a trilby. Or a crocodile wearing a fez. Or a tram wheel and a dollop of porridge. Rentwa 15:34, 1 September 2006 (UTC)

Chin up, Rentwa. Sooner or later we all learn that providing answers to questions posed by anonymous ingrates is, like patience, its own reward. When you get to the point of making posts for the pure joy of doing so, without regard to whether or not anybody ever reads them, or if they do, what they might think of them, or of you, then you will have achieved true Wiki-transcendence. JackofOz 12:56, 3 September 2006 (UTC)

Steorn and Free Energy

What is the deal with these Irish people who claim to have proved false a large portion of scientific knowledge? It can't be true what they are saying; what are they trying to do?

Its too good to be true! (so it isnt)--Light current 04:59, 31 August 2006 (UTC)

I know, but I mean is this an ad campaign or what. --216.164.200.120 05:05, 31 August 2006 (UTC)

So far, they are maintaining it is genuine. However, as with all claimed scientific breakthroughs, it should probably be treated with skepticism until the process has successfully cleared the peer review process and the work been reproduced by other scientists. It does seem an extraordinary claim, but then again, the idea of a telephone or television was probably as fantastical at some point in time. Rockpocket 05:09, 31 August 2006 (UTC)

Probably problems with the measurements!--Light current 05:11, 31 August 2006 (UTC)

To be perfectly honest, how many legitimate scientists run ads in The Economist? Or set up flashy pages on flashy websites that seemingly were not used for any serious scientific stuffs before hand? Most legitimate scientists would at least hold back somewhat on something like this until they got some level of confirmation, rather than stirring up a media storm right away. There are also normal channels to go through instead of magazine ads. Anyways, best policy is probably to just take it with an enormous lump of salt until peer review is done with; if you took every revolutionary scientific claim completely seriously, you'd lose your mind in little time. -- Consumed Crustacean (talk) 05:21, 31 August 2006 (UTC)

The television and telephone were perfectly explainable using existing scientific theories. This "free energy" appears to directly contradict the laws of physics (which are not really "laws", but have been observed to hold true by physicsts, in this case for centuries). --Robert Merkel 05:27, 31 August 2006 (UTC)

You'll note i said "at some point in time". I'm sure, prior to the establishment of modern "scientific theories" the idea of seeing or hearing someone from another continent would be considered to contradict the "laws of physics" as we understood them at that time. Throughout history, when someone has challenged the paradigm, their works was initially mocked, see Reaction to Darwin's theory for example. I'm not suggesting the Steorn claim is genuine, but equally, it is scientifically flawed to argue it is fake based on a dogmatic adherence to so-called "laws". The fact is we do not yet know. Rockpocket 05:53, 31 August 2006 (UTC)

Yes, but at the time they were invented they were perfectly in harmony with the laws of physics as understood. This gadget isn't. And thousands of other proposed perpetual motion devices have failed before. It's not impossible this one is different, but it's pretty damned unlikely. Extraordinary claims require extraordinary evidence. --Robert Merkel 09:00, 31 August 2006 (UTC)

I'm sure there are plenty of theories or hypotheses (potential "laws") that could accomodate perpetual motion machines, its simply that they are not accepted by the mainstream as scientific. The reason they are not accepted by the mainstream is because it has hitherto proved impossible to prove (in this case empirically) and it does not sit comfortably with our current level of understanding. I completely agree that it is "damned unlikely" to be true, but if it was duplicated independently that would be extraordinary evidence. I'm willing to keep an open mind until then and not pre-judge. Remember we should be giving NPOV answers here whenever possible. Rockpocket 04:58, 1 September 2006 (UTC)

Lots of science is rubbish - thats why scientists are able to change their theories every few years! Evolution -> predicts new species evolve, but what do we observe? No new species evolve, but lots of existing ones go extinct - opposite of what theory predicts yet people still support it and in fact most Biologists actually think it's a Law of Nature!

Dark matter - cosmologists use theory to guess weight of Universe, then use observations to estimate weight - two figures disagree - sane person would assume theory wrong and evidence of eyes right, cosmologists invent special invisible matter to make theory right! [/rant] Rentwa 05:47, 31 August 2006 (UTC)

btw, we do see new species emerging, and evolution is not the oppposite of species going extinct. In fact, species that cannot evolve fast enough to new circumstances (ie, people with guns who kill more than the population can replace) would be expected to go extinct. 86.140.31.143 13:12, 31 August 2006 (UTC)

Where do you get the idea that no new species evolve? Darwin proved that species are evolving right now with the various new speciations being done on the Galapagos Islands. New species of moth were being created in Great Britain due to the sooty trees, but cleaner air has stopped the complete speciation of black and white moths. User:Zoe|(talk) 02:38, 1 September 2006 (UTC)

I'm trying to make a point about logic in scientific reasoning, or Empiricism vs. Theory, or the varying degrees of quality in scientific arguments. Darwin didn't prove anything. Just because something seems to be a plausible explanation doesn't mean it's true. 'If it looks like a duck...' may be acceptable reasoning in real life, but I think people interested in knowledge (ie scientists) should look into things more deeply. God and creationism looked like a pretty good explanation for the world pre Science, after all.

On more concrete matters - what new species have we observed on the Galapagos? I mean species that weren't there when people arrived and documented the existing fauna and have arisen since? None as far as I'm aware. Re the moths - the black form prospered during Industrial times and the lighter form is prospering now. So what? Not remotely like a new species evolving. Rentwa 13:10, 1 September 2006 (UTC)

It's obvious you're not interested in a real discussion. User:Zoe|(talk) 02:01, 2 September 2006 (UTC)

No. Humanity is responsible for wiping out lots of species, so it is a moral imperative for us to understand the mechanisms of biology so that we might correct ourselves. Evolutionary models are indispensible for investigations into the diversity of life. Dark matter is a hypothesis that makes many more important predictions than you seem to be aware of, and I can only refer to the article for those. It is necessary to hypothesize dark matter and reason about its properties so that we know how to look for it and decrease our ignorance. And no one is more careful to hedge statements about the unknown and verify theories than scientists. If you have been given a different impression by a hostile and uneducated press with no interest in the subtleties of knowledge, perhaps you should look to new sources of information. Melchoir 06:26, 31 August 2006 (UTC)

I'm ranting a little - the shortcomings of science is one of my pet bugbears (and I'm right too - see my original point - if the theories were correct it wouldn't be possible to revise them), but re your point about knowledge - my impressions were gained at an ancient British university, and it's academics, I'm afraid, who are the blindest of all to its subtleties.

This chap, btw, is quite good on free energy. Rentwa 06:46, 31 August 2006 (UTC)

A theory does not have to be absolutely correct to be useful to scientists and society alike. This is a strength of science, not a shortcoming, because we cannot and should not expect to be certain about anything. As for academics, my personal experience of researchers is that the successful ones are quite aware of the historical wrong turns their fields have taken. Melchoir 06:58, 31 August 2006 (UTC)

There's a spectrum of theory quality. Gibbs Free Energy above (misunderstanding of name possibly accounting for current interest) is brilliant, as is most of Thermodynamics. Unfortunately (as I'm sure you would agree) that's one end of the spectrum.

And I disagree completely with your observations on successful researchers (perhaps I'm just bitter!) Orthodoxy is the thing that counts. Rentwa 07:13, 31 August 2006 (UTC)

Fair enough. I won't claim to be a sociologist! Melchoir 08:32, 31 August 2006 (UTC)

No, honestly, I was ranting! (Don't_disrupt_Wikipedia_because _you're_too_mean_to_pay_for_therapy) ;-) Rentwa 08:39, 31 August 2006 (UTC)

Atoms

Can scientists directly see atoms? What kind of microscopes are used? If it's still impossible, what capabilities would a microscope require in order to be able see the atom?

I was just wondering. I assume electron microscopes are used to get a sense of the election cloud surrounding an atom's nucleus but viewing the nucleus itself isn't yet possible. I'm not sure though. - Pyro19 08:53, 31 August 2006 (UTC)

Microscope is a good (and obvious) starting point. That leads you to Scanning tunneling microscope. Another one would be atom, where you can search for 'microscope'. DirkvdM 09:17, 31 August 2006 (UTC)

• A common way to get a look at atoms (be it indirectly) is X-ray crystallography. And another method (actually the first) to actually visualise atoms is the field ion microscope. an actual picture [7]. Xcomradex 10:25, 31 August 2006 (UTC)

Wow, never knew atoms were so slimy-looking. :) DirkvdM 09:14, 1 September 2006 (UTC)

With all of these visualizations there are a lot of assumptions which have to be made about the data—you are never really looking at the "atom itself" in the way that one normally thinks of "looking", so it is all "indirectly" in a sense. But once you start really interrogating what "looking" means at the atomic and subatomic level, it gets pretty hard to say that you see anything "directly". In any case, the most famous picture of individual atoms is the IBM logo made out of 35 Xenon atoms. As you can see, they look more like probability functions than what one might expect an actual atom to "look like" from a human point of view. --Fastfission 14:54, 31 August 2006 (UTC)

Claiming that's the IBM logo is a bit much. Let's be reasonable here and just call it what it is, the letters IBM.  freshofftheufoΓΛĿЌ  13:02, 1 September 2006 (UTC)

The definition of "looking" is something to note here. The most common way to "look" at something is to throw things at it, and see what they do. That is why we make particle accelerators (atom smashers), so we can "look" at things that we can't "see." In normal life, we do this. One could say when you switch on the light bulb, photons fly out and bounce off of objects, and the photons eventually reach your eye. Based on the qualities of the photons that reach your eye, you "see" objects. — [Mac Davis] (talk) (Desk|Help me improve)

Wait, there's something I'm still not getting. Is it impossible to see an atom due to quantam effects or something? That picture that Xcomradex linked to, are those little round balls actual individual atoms or are they an approximation? - Pyro19 15:24, 1 September 2006 (UTC)

You can only clearly "see" something using a wavelength that's quite a bit smaller than the size of the object you're trying to see. Oridnary light in the visible spectrum clearly won't do for visualizing individual atoms; the atoms are smaller than the wavelength of the visible light. So you'll never be able to use your eyes directly through some kind of ultramicroscope to see an atom. That's where the shorter wavelengths used in X-ray crystallography come into play. But even those are pretty big and the atoms aren't imaged individually. Instead, they act en mass like a diffraction grating.

Instead, we use particles that have the equivalent of a very short wavelength (those "ions" that were mentioned above in the field ion microscope).

Alternatively, we can use actual touch (or the quantum equivalent of "close enough"). That's how the various scanning tunneling microscopes, atomic force microscopes, and the like work.

Atlant 00:33, 6 September 2006 (UTC)

Distance traveled by a soccer ball when kicked in different angles.

When a soccer ball is kicked at an angle exactly paralled to the ground, that is , making an angle of 0 degree with the ground, will it travel more horizontal distance or when it is kicked making a certain angle with the ground  ? Force applied in both the cases is taken as same.

I'll leave to that someone more capable, but essentially zero degrees would either mean slipping or rolling, right? Well, it depends on the material of the ground : grass, ice,... Evilbu 11:32, 31 August 2006 (UTC)

I think you have to clarify your question... do you mean kicking it down or up? If you kicked it up it would most certainly travel further than kicking it along the ground for angles less than 45 to the ground. Kicking it downwards should cause it to bounce and lose a lot of energy on impact with the ground, but exactly how much energy it loses is hard to say... you might have to stage a real-life trial to figure that out.  freshofftheufoΓΛĿЌ  12:03, 31 August 2006 (UTC)

I think the question is, essentially, what is the optimum angle to achieve the greatest distance. According to our trajectory article, this is 45 degress.--Shantavira 13:57, 31 August 2006 (UTC)

While 45 degrees is absolutely correct for idealized cannonballs, soccer balls will behave differently. I'd put "optimal" at a lower angle, say 20 to 30 degrees, to keep most of the air time while reducing the energy lost at landing and improving the horizontal speed component for the post-landing roll. — Lomn | Talk 15:12, 31 August 2006 (UTC)

It is 45 degrees if the ball does not spin. Forward spin or back spin will alter that a bit. --Kainaw ^(talk) 15:14, 31 August 2006 (UTC)

When a goalie kicks it as far as he can, it is at a much greater angle than 30 degrees. --liquidGhoul 15:15, 31 August 2006 (UTC)

It's worth noting that when the goalie kicks the ball, the ball never goes as far as it could. There are always players in the way; those players aren't going to let a ball bounce and roll out to its maximum distance. The angle at which the ball leaves the goalie's foot is going to be something of a compromise.... TenOfAllTrades(talk) 15:21, 31 August 2006 (UTC)

45 degrees is correct for ideal cannonballs on the moon—that angle doesn't take into acount the effects of air resistance. When we look at bouncing and rolling, then you have to take into account the properties of the ball and the grass; it's a mess. TenOfAllTrades(talk) 15:21, 31 August 2006 (UTC)

...only if the moon has a radius much larger than the cannon's range, and its muzzle velocity is small compared to the moon's escape velocity. Skimming those articles for numbers, the assumption doesn't look so good. So really, 45 degrees is correct in thought experiments and textbooks. Melchoir 17:18, 31 August 2006 (UTC)

Okay, okay. 45 degrees is the optimum in an airless environment where the curvature of the surface is negligible compared to the length of the ball's trajectory and the gravitational acceleration is approximately uniform throughout the ball's flight. Once you start removing those assumptions the calculation quickly starts getting difficult. To a first approximation, since it has air resistance, the best angle to kick a soccer ball for maximum range would be a bit below 45 degrees, although I can't calculate it exactly since I don't know the drag coefficient of soccer balls, and am not taking into accounts the effects of spinning the ball... — QuantumEleven 07:34, 1 September 2006 (UTC)

specific question for medicine/hematology

Dear Sirs,

I have read a certain writing on a disease/disorder called hyperkaliemia and I understand that it is composed of hyper-, kalium (potassium)and (a)emia (referring to blood). Where can I find more specific info on the disease because I could not find anything in the Wikipedia. Greatful in advance for any help from your specialists.

Very truly yours, Mr. Antti Stenberg Helsinki, Finland82.181.113.180 12:06, 31 August 2006 (UTC)

You were close. It's spelled Hyperkalemia. -- Plutortalkcontribs 12:26, 31 August 2006 (UTC)

Redirected. You can help!  freshofftheufoΓΛĿЌ  12:39, 31 August 2006 (UTC)

Surviving by drinking seawater

I have read accounts of shipwrecked people who claimed to have survived by drinking seawater, while other accounts--including Wikipedia--state that this is likely to lead to kidney failure. What is the correct answer? --Mugogo

• Kidney failure, salt water just doesn't quench thirst, it makes it worse. Even if you could drink large amounts of it, it wouldn't do you any good unless you made a point of distilling it first--VectorPotential^{71.247.243.173} 16:10, 31 August 2006 (UTC)

Also, try not to eat things that will not benefit you after digestion. If you eat your leather boot, your stomach may be filled, however you are killing yourself by spending more energy trying to digest a boot that has no nutritional value to you whatsoever. Regarding the water, you can distill seawater or urine, then drink the product. Solar stills are the most common and efficient way of doing this. — [Mac Davis] (talk) (Desk|Help me improve)

Do you actually need to distill the urine? I heard it can be drunk raw/neat/warm. Our page:

Urine on the other hand contains salt, which makes it unsuitable to drink. You can, however, make drinkable water from urine by distilling it.

So if there was little or no salt you could drink it. Otherwise you could try to remove the salt somehow.

--Light current 16:45, 31 August 2006 (UTC)

The other question is the stuff that causes the yellow/brown pigmentation of urine. Also theres urea. Im not sure what effect that has if it builds up in the body.--Light current 17:17, 31 August 2006 (UTC)

Too much urea will become toxic. People who wet the bed also know that it causes a nasty skin rash. The brown pigmentation is due to red blood cells and their broken down constituents that have made it through the renal filters. You shouldn't drink distilled urine unless you could guarantee you've distilled pure water out of it, which is unlikely if you're stranded at sea with a makeshift distiller. Nimur 17:38, 31 August 2006 (UTC)

You could always try eating the cabin boy.--Shantavira 17:30, 31 August 2006 (UTC)

Having quickly read that art, it seems to me they were unjustified in eating him after only 8 days or so. Im sure humans can survive a coulpe of weeks with no food.!--Light current 17:45, 31 August 2006 (UTC)

Actually, the yellow color comes from urochrome and bilirubin. While excess levels of bilirubin in the blood can be toxic, I am unsure whether ingesting them would cause them to accumulate in the body or whether they would be broken down by the digestive process. Plus, sunlight helps the body breakdown bilirubin, thus if you are stranded on a raft out at sea and decide to drink your urine, there would be plenty of sun to help you brak down all that bilirubin! Nrets 17:36, 31 August 2006 (UTC)

So the moral of the story is: make sure yuo take a small still with you into the life boat and drink as much as you can before abandoning ship! Also looks like that art on urochrome needs expanding considerably.--Light current 17:49, 31 August 2006 (UTC)

However, drinking pure distilled water is not good for you either, as it contains no electrolytes and will wash everything out of your body. You may be best off with neat urine (for the electrolyes) diluted with the distilled stuff (might taste better too!)--Light current 18:00, 31 August 2006 (UTC)

Why would that be? I never considered it, but always thought your body's maintenance, requiring water— distilled water would suffice somewhat. Ok, bad sentence construction, but you get what I am trying to say. — [Mac Davis] (talk) (Desk|Help me improve)

Distilled (pure or deionised water) I believe is very attractive to ions of potassium , sodium etc in the body and will leach them out leaving you short!--Light current 19:34, 31 August 2006 (UTC)

Add a teaspoon of sea water. --liquidGhoul 23:54, 31 August 2006 (UTC)

After the revolutionary army (as far as one can call it that) landed in Cuba they got into big trouble and after a while found themselves with little drinking water in a saltwater environment. So Che said he had read that if you mixed the drinking water with salt water you could double your available water. So they tried that. This made Che very impopular over the next few days. :) DirkvdM 09:25, 1 September 2006 (UTC)

A very old military practice is to put salt in drinking water - not to increase the water, but to increase the body's ability to hold water. A little salt will increase absorbtion. Too much salt, and you lose water. You judge it by how much you urinate. Keep adding salt until you urinate much less frequently. Then, if you continue adding salt, you will urinate a LOT more (and it is a bit painful). I was lucky. My body likes two standard issue packets of salt per standard issue canteen. No worrying about half-packets or anything like that. --Kainaw ^(talk) 19:11, 1 September 2006 (UTC)

I understand that one shouldn't have more than 6 grams of salt per day, as a nutritional rule of thumb. While this information generally relates to adding salt to meals, I believe it serves as a rough average of how much daily salt intake is considered "healthy" (by British standards.) CptJoker 02:08, 3 September 2006 (UTC)

But the gram is an SI unit, so British standard don't apply here. DirkvdM 05:27, 3 September 2006 (UTC)

Physics

Why are Germanium and Silicon which have 4 valence electrons classified as semiconductors, whereas Carbon which also has 4 valence electrons is vlassified as an insulator?…—Preceding unsigned comment added by Salvadesswaran ps (talk • contribs)

Diamond#Electrical properties might help. It's not much, though. Melchoir 16:43, 31 August 2006 (UTC)

Carbon is not an insulator. I think it may be classed as a semiconductor.--Light current 16:52, 31 August 2006 (UTC)

Graphite is a conductor. Nimur 17:10, 31 August 2006 (UTC)

For the full story, there are many allotropes of carbon. I think diamond is the most relevant to the analogy with silicon and germanium. Melchoir 17:12, 31 August 2006 (UTC)

Agreed - depends on the form. Its either a semi conductor (diamond) or a conductor. I dont know of any insulating forms.--Light current 17:32, 31 August 2006 (UTC)

In other news, check out the French link under "in other languages" for Aggregated diamond nanorods. Honestly, nanobaguettes? How do they say that with a straight face? Melchoir 17:38, 31 August 2006 (UTC)

Diamond is a semiconductor. I went to an interesting lecture last year on the current research into diamond semiconductor research and promptly forgot most of it, but I do remember that diamond semiconductors can operate at my higher temperatures than silicone and are also completely non toxic in the body (andriods anyone)? Theresa Knott | Taste the Korn 17:39, 31 August 2006 (UTC)

and don't forget the bigger picture, the periodic table, and metalloids. Xcomradex 21:38, 31 August 2006 (UTC)

Whether a solid material is a conductor, semiconductor or insulator depends on a parameter called the band gap, the energy difference between the "valence band" (where there are electrons) and the "conduction band" (where they would have to go in order to help conduct electricity). In conductors, there is no band gap, so the electrons are free to conduct. In insulators, the band gap is "large", and there is no conduction. In semiconductors, the band gap is "small", so that a few electrons can be kicked up into the conduction band by thermal excitation (their heat energy), especially if they are helped along by the trick called doping. Clearly the boundary between "small" and "large" band gaps is fuzzy. Diamond has a larger band gap than silicon and germanium, and under normal conditions behaves mosty like an insulator (being essentially insulating to electricity, being transparent to light, etc.). However, its band gap is much smaller than those of typical insulators, and diamond does behave as a semiconductor at higher temperatures, or if doped. There is a fair bit of research on diamond semiconductor devices, so stay tuned for cool products in the future. mglg_(talk) 22:39, 31 August 2006 (UTC)

Science of gayness

What disturbances in childhood cause gayness? Also, if there is a genetic component(as found in fruit flies), to what extent does it affect humans? --216.164.200.224 16:58, 31 August 2006 (UTC)

Check the homosexuality or human sexuality articles for a baseline. This is a topic which doesn't have a precise answer; a lot of research is still ongoing. Nimur 17:09, 31 August 2006 (UTC)

Doesn't the relative commonness of homosexuality rule out genetics? Two people of the same sex can not produce a baby of their own passing on their genes if they are fittest? I guess we would have to go to Papua New Guinea to see how gay people are there and compare it to, say, the United States. — [Mac Davis] (talk) (Desk|Help me improve)

Mac you have a lot to learn about genetics. By that argument, brown eyes and black hair and heterosexuality have no genetic basis-- in fact, by that argument, being male or female has no genetic basis. alteripse 20:05, 31 August 2006 (UTC)

A putative gene for gayness might predispose for strong sexual attraction towards men and reside on an autosomal chromosome, and thus create this attraction irrespective of whether the carrier was male or female. The benefit of increased reproduction of female carriers might outweigh the reduced reproduction of male carriers of the gene. --N·Blue ^talk 19:51, 31 August 2006 (UTC)

I've heard of several sets of identical twins where one was gay and one was not, so it's unlikely to be purely genetic. At the same time, I would think it extremely unlikely that something like this wouldn't have a genetic component. At a personal guess, there is probably an inherited tendency which, for whatever reason, is sometimes expressed and sometimes not. Skittle 20:14, 31 August 2006 (UTC)

Fruit flies have nothing to do with human genetics—they are just model organisms with which we understand different aspects of how genetics works; they do not tell us anything much about the actual expression of human genetics (anymore than human genetics would tell us about fruit flies). --Fastfission 20:21, 31 August 2006 (UTC)

What do homosexuals call themselves? Homosexuals or gays? I dont theink the original title was offensive to anyone. Please change it back! 8-(--Light current 20:27, 31 August 2006 (UTC)

What disturbances in childhood cause gayness? I admit I cringed when I read "disturbances", as it seems to imply that it takes something wrong/bad/weird (i.e., not an amoral event) to turn a child gay or something. But, despite the poor word-choice, there's a good question here.

First off, it's important to not think of sexuality in binary terms; the Kinsey scale or Klein Sexual Orientation Grid are sort of a crude measurements of where one might fall in this spectrum. Biology and sexual orientation & Choice and sexual orientation may have more useful, relevant information, too. Whether one is "gay" is a quasi-subjective establishment--obviously those that have only ever been exclusively attracted to and sexually active with one sex are pretty clearly "straight" or "gay", but there's a very large portion of society that doesn't fit perfectly into those categories.

For the genetics: there will (likely) never be a single definitive, all-encompassing "gay gene" discovered because, frankly, it would most likely be readily selected against. But, there are genetic regions that associate with homosexual traits.[8] These may, among other things, encode differential development of the sexual dimorphic nucleus, efficacy of aromatase, or perhaps some temporal difference in hormonal signaling during fetal development, for example. It's still largely unexplored.

Finally, the preponderance of scientific evidence is that human sexuality is determined, in large part, by genetic and epigenetic control of developmental processes (and maybe some important effects in olfaction). But, probably not 100%...the way I'd think of it: imagine that spectrum as simple line or axis, continuous rather than segmented into integers as in the scales above; one's genetic & epigenetic characters probably define a narrowed region of said spectrum as the destinations for one's sexual identity. Environmental factors, in and out of one's control (such as maternal hormonal effects in utero or sociological forces), narrow it to a single (but not necessarily immobile) point. -- Scientizzle 23:59, 31 August 2006 (UTC)

Very nice answer, Scientizzle *round of applause* Rockpocket 04:46, 1 September 2006 (UTC)

Thanks. -- Scientizzle 04:57, 1 September 2006 (UTC)

On NorwegianBlue's comment: yes, that would make sense. See also [9] which has a similar but more complicated idea. – b_jonas 13:02, 2 September 2006 (UTC)

biogas

how do biogas reactors produce pressurized methane without pumpos?

Anaerobic digestion has your answer. The way I see it, they just grind up the pumpos and throw it in! --Zeizmic 20:11, 31 August 2006 (UTC)

Carbon

What is it about carbon that allows it to have some many allotropes and forms with such differing properties. Is any other element so versatile. Im not a chemist, so can you keep it simple? Thanks--Light current 20:16, 31 August 2006 (UTC)

• Allotropy also makes the point of elements having multiple oxidation states (many workable arrangements of electrons) and variable co-ordination numbers (many workable arrangements of neighbouring atoms) (both apply to carbon) having more allotropes. and there are other elements with large amounts of allotropes too,eg. black, white and red phosphorus for example; oxygen, ozone and tetraoxygen, and sulfur has even more than carbon. Xcomradex 21:47, 31 August 2006 (UTC)

So sulfur could produce some interesting forms? Is that right? Are all these elements in a particular region of the periodic table as well?--Light current 21:52, 31 August 2006 (UTC)

Looks like theyre all in the non-metals part. How gratifying! So Selenium may have the same allotropic versatility as well?--Light current 21:57, 31 August 2006 (UTC)

• you got it. there's red powder selenium, red crystalline selenium, as well as the useful gray semi-metallic selenium. Note that one of the allotropes of sulfur is S₈; likewise selenium has an allotrope Se₈. don't you love the periodic table B-) Xcomradex 22:08, 31 August 2006 (UTC)

Seems good to me!--Light current 22:10, 31 August 2006 (UTC)

• If you're in search of more allotropic fun, or other periodic table stuff, [10] is good site. Xcomradex 22:22, 31 August 2006 (UTC)

Isn't this versatility of carbon a reason it is a basis of life on Earth? And if so, could life then be based on something like Selenium or Sulphur? DirkvdM 09:31, 1 September 2006 (UTC)

yeap. alternative biochemistry. Xcomradex 11:05, 1 September 2006 (UTC)

Silicon is the only other equivalent to carbon, the others differ in ways, but can be made to work. Philc _T^E_C^I 15:23, 1 September 2006 (UTC)

Silicon is a rather poor substitute for carbon, mainly due to its lower electronegativity and the larger size of its p-orbitals. Pure silicon analogues of organic compounds, such as silanes, simply don't hold together as well, especially where double bonds are involved. Silicon can replace a carbon atom in a mostly carbon molecular framework, but such organosilicon compounds are often reactive and break easily apart at the silicon atom. See also Silicon#Silicon-based life. —Ilmari Karonen (talk) 19:45, 2 September 2006 (UTC)

Orangutans in TV and Movies

I have seen trained Orangutans in American movies and Television,.How is it legal for for Animal trainers (and other private individuals) to own and exhibit Orangutans when they are an endangered species, And where are these people buying them from? I know they are not imported from the wild anymore.—Preceding unsigned comment added by 74.234.31.7 (talk • contribs)

• Unless they're eating and/or sterilizing the Orangutans, I don't suppose that simply having them on film would do much to jeopardize their conservation status--71.247.243.173 22:48, 31 August 2006 (UTC)

there is a danger that such orangutans may become acustomed to the movie star lifestyle, and be unable to find bagels in the wild. Xcomradex 22:55, 31 August 2006 (UTC)

How much do they get paid for appearing in films?--Light current 23:25, 31 August 2006 (UTC)

I've heard they work for peanuts, but that may be elephants--71.247.243.173 23:30, 31 August 2006 (UTC)

The problem with using them, is that people are making money from an endangered species. If it is profitable to exploit them, then it is more likely people will take them from the wild. Also, most zoos and such have breeding colonies, so they can release them into the wild. If the orangutan is being used for television instead of being in a breeding program, that will lower the diversity of those which are released, and lower their chance of survival as a species. --liquidGhoul 23:44, 31 August 2006 (UTC)

Seeing as how our article on Orangutan#In_popular_cultureOrangutans, only has 3 pop culture references, one of which is a cartoon, I don't think they actually are used in film/TV all that often, if at all--71.247.243.173 00:18, 1 September 2006 (UTC)

The last one I remember was Clyde appearing with Clint Eastwood.--Light current 00:20, 1 September 2006 (UTC)

Dunstan Checks in , George of the Jungle, Baby's Day Out, Fear and Loathing in Las Vegas,Babe 2 Many comercials for among other things Credit Cards, Tang, Domino's pizza

• The last time I saw Orangutangs (sp?) was in Serious Jungle and that program was about conservation and they were still in the wild. - Mgm|^(talk) 08:04, 1 September 2006 (UTC)

Yeah, last time I checked, it was a gorilla in George of the Jungle (film), and wasn't it a robot?  freshofftheufoΓΛĿЌ  12:47, 1 September 2006 (UTC)

I was not refering to George's talking side kick "Ape" .There were orangutans as background characters in the moive along with Chimps , Capuchin Monkeys and other primates.

Yes, I do believe there were. In cages? At a zoo? It's been a long time since I saw that movie.  freshofftheufoΓΛĿЌ  07:02, 2 September 2006 (UTC)

automotive

I am trying to figure out more information on car's body stiffness. Can you help? —Preceding unsigned comment added by 65.169.154.2 (talk • contribs)

Cars with frames tend to be stiffer than unibody cars. Modern cars tend to be intentionally designed not to be stiff, so they will collapse in a severe impact, thus reducing the deceleration effect on the passengers. See crumple zones. What other info do you want ? StuRat 00:11, 1 September 2006 (UTC)

The term can be used in a variety of ways. StuRat has explained how compressional stiffness is important to a car: safety is increased in cars which "crumple" within certain bounds. Car manufacturers often will subjectively rank torsional stiffness between models. A higher torsional stiffness will help keep all four wheels on the road in tight turning situations. A lower torsional stiffness is why convertibles often handle "worse" than similarly specified coupes. Also important is resistance to bending, or sheer forces. This type of stiffness is more complicated. Anti-roll bars, for instance, will be more resistant to sheer stresses and help both tires on opposite sides of the car stay in synch. However if sheer stress is increased too much, any stresses or damage that would have previously only affected only one side of the car will now affect both sides. Stiffness is also a term used to describe various shock-absorbing apparati between the wheels and the chassis, but since you asked specifically about the body stiffness, I'll spare you.Tuckerekcut 00:34, 1 September 2006 (UTC)

September 1

nature cure

respected whomsoever,i am a naturopathy and would like to have answer for a question in water therpy of nature cure. "Why do we use cold water therapy?" I need to have a scientific approach to this answer

We need to have a slightly more detailed question.--Light current 03:41, 1 September 2006 (UTC)

this could be interesting, given naturopathy and science are pretty much mutually exclusive Xcomradex 03:56, 1 September 2006 (UTC)

Check out Hydrotherapy for history and techniques, Naturopathy for references to scientific (and governmental) assessment.---Sluzzelin 05:42, 1 September 2006 (UTC)

Unknown green insect

What is this insect? Which species, family, or order? The photo was taken in Gyeonggi-do, South Korea. --Kjoonlee 03:24, 1 September 2006 (UTC)

Some type of walking leaf, I would guess. Here's a pic of the Malaysian Walking Leaf: [11]. StuRat 03:34, 1 September 2006 (UTC)

I give up, this ones too hard. I'm guessing that the two front legs are held up in front of it's face or something, but I can't find anything like that with a flat back, and I've just sifted through a few thousand images. It seems leaf insect is a bit more technical than walking leaf, though they both refer to the (huge) Phasmatodea (and the possibly more relevant Phylliidae) anyways.  freshofftheufoΓΛĿЌ  12:40, 1 September 2006 (UTC)

Thank you. :) According to SNU's insect taxonomy website, It's Neotituria kongosana. Here are some other photos: [12] --Kjoonlee 13:31, 1 September 2006 (UTC)

A sort of leafhopper. Cicadellidae, Ledrinae, Petalocephalini, Neotituria kongosana. --Kjoonlee 13:46, 1 September 2006 (UTC)

I susupected it was some sort of leaf hopper, but I couldn't find any that had such a flat shell structure. Most of them seem to look like the first 2 in that link you gave. All of my sources were English, though, and about 99% of the images were from the US, so I guess that explains why I couldn't get any closer : (.  freshofftheufoΓΛĿЌ  06:59, 2 September 2006 (UTC)

Hoodia Gordonii

What is it and how does it work and how much of it do you take?

See Hoodia. Melchoir 04:41, 1 September 2006 (UTC)

Hoodia trust for medical advice? Edison 17:01, 1 September 2006 (UTC)

neutron star

what is a neytron star.is it possible to get some or addsome neutron in that star?

All is revealed at neutron star. Search first; it's quicker.--Shantavira 06:18, 1 September 2006 (UTC)

First make sure you understand your own question, though. DirkvdM 09:34, 1 September 2006 (UTC)

medical

If an injured swimmer was to drown and the red blood cells found in the lungs were swollen and had burst, did the person drown in fresh water or sea water? Given that the tonicity of sea water is greater than that of the cytoplasm of blood cells , and the tonicity of fresh water is less than that of red blood cells, explain how you reached your conclusion. What process has occured in this situation? thanks Johanna

Sorry, you should probably do your own homework. Tonicity might be a good place to start. -- Plutortalkcontribs 12:27, 1 September 2006 (UTC)

Actually, you should ask for better homework questions. People who drown have water in their lungs, not blood. Their blood is in their circulatory systems, before, during, and after drowning. The question should allude to lysis of RBCs within the lung capillaries, not "in the lungs". Freshwater is hypotonic and flows rapidly through the pulmonary capillaries overloading the heart and causing lysis of RBCs with K⁺ release. Death is rapid. Saltwater is hypertonic and there is no mass fluid transfer; death is slower and has a strong asphyxial component. - Nunh-huh 21:08, 1 September 2006 (UTC)

There are lots of ways to die of immersion, including sudden arrest, air embolization, asphyxial suffocation without water inhalation, etc. See [13] for a fairly good overview. The question is easy based on test-taking skills: the questioner is obviously ignorant about drowning and doesnt care about drowning but wants to see if you understand the isolated concept of hypotonic versus hypertonic fluid effects on rbcs. The question would be the same if they asked what would happen to rbcs dropped into a hypotonic or a hypertonic solution.alteripse 23:55, 1 September 2006 (UTC)

Difference between PRECISION & ACURRACY?

What is the clear-cut distinction between precision & accuracy?

• Accuracy and precision. Weregerbil 12:58, 1 September 2006 (UTC)

A nice example is that if I said I was 6.32456m tall, it would be high precision but low accuracy. If I said I was 1.5m tall, it would be less precise, but more accurate. —Daniel (‽) 13:13, 1 September 2006 (UTC)

Why. How tall are you?--Light current 20:42, 1 September 2006 (UTC)

Assuming that the number of figures is used as an indicator of the precision. —Bromskloss 13:50, 1 September 2006 (UTC)

It ought to be, when reporting a measurement. See significant figures. TenOfAllTrades(talk) 15:24, 1 September 2006 (UTC)

Well, the real difference, is that PRECISION is what they ask you in about in a freshman lab course, where as ACURRACY is what they ask you about in lecture, 2 completly different types of homework you want us to do for you--71.247.243.173 19:03, 1 September 2006 (UTC)

Kid in a natural history museum: "Hey mister, how old is that dinosaur ?"

Guard: "200 million and 8 years old."

Kid: "You mean 208 million years old ?"

Guard: "No, I mean 200 million and 8."

Kid: "But how do you know so precisely ?"

Guard: "Well, it was 200 million years old when I started working here 8 years ago, so..."

StuRat 00:59, 2 September 2006 (UTC)

Cattle in a feedlot

I know that before slaughter, many cattle are housed in a feedlot to be fattened up. I would like to know about how long an animal will typically stay in the feedlot. ike9898 13:08, 1 September 2006 (UTC)

According to this page that used to be on Harris Feeding Company's website, "cattle typically spend approximately 12 to 16 months grazing; then, at 650 to 750 pounds, enter the feedlot for about 3 to 4 months to gain an additional 400 pounds or so." -- Plutortalkcontribs 15:00, 1 September 2006 (UTC)

Could you add that to the article? Rmhermen 16:51, 1 September 2006 (UTC)

Yeah, I'm also trying to find another source. ike9898 20:37, 1 September 2006 (UTC)

Acetone as an additive for gas and diesel?

I read that adding minimal amounts of acetone to gasoline and diesel would increase mileage considerably. My question is if that is really the case. Also, of course, the car should not get damaged if one were to do this (especially the catalyst). Last but not least, would this increase, decrease or not affect exhausts at all? Thanks for your answers, RichiH 13:25, 1 September 2006 (UTC)

Off the top of my head, I can't think of any reason why acetone should improve mileage, mile per joule, more than any other fuel, so it sounds wrong to me. Again, off the top of my head, the only additives that make a difference to engine operation beyond their calorific value are things that affect the octane rating of the fuel (and they really affect smoothness of operation rather than efficiency), and I can't see acetone doing this.

Catalysts are primarily damaged by lead additives which coat the Pt/Pd, acetone certainly wouldn't do this.

The major problem I see with using acetone as a fuel is that it mixes with water, so using pure acetone would mean having water in the engine which would corrode it. Same reason why you dont use washing-up liquid as a lubricant, even though it's ideal in most other respects.

Actually this is an advantage. Having Acetone absorb the water and carry it through the engine is a good thing, unless you are talking about a lot of water. 12.41.204.3

No it isn't. You shouldn't contribute to topics in which you have no formal knowledge, particularly to contradict people who have. You've also been told before to sign your comments. Rentwa 17:21, 1 September 2006 (UTC)

The burnt acetone would come out in the exhaust just like the other burnt chemicals - it wouldn't have any disproportionate effect on exhaust.

If you can provide a link to the original article or quote it, it might help. Rentwa 13:54, 1 September 2006 (UTC)

I would have provided the link, but it's on another box and i do not have access to that, right now :/ RichiH 18:04, 2 September 2006 (UTC)

I think i found the page, again: [14]. Googling also showed this: [15] which points to here: [16] RichiH 18:18, 2 September 2006 (UTC)

Thanks Richi. The molecular theory sounds pretty good (so did the theoretical explanations of Cold Fusion). Petrol/Diesel are mostly hydrocarbons, like sticking to each other, don't like sticking to acetone. Mix a bit of acetone in and it breaks up the whole thing, so there's a lot less sticking going on. And hey presto, the fuel is easier to vapourise, burns more efficiently etc etc.

However, from a thermodynamic point of view this is saying that a little drop of acetone is doing one hell of a lot of work - it's like putting a drop of something into a cup of water and the water boiling. You can get a rough idea of the amount of free/magic work the acetone is supposed to do from the claimed fuel efficieny improvements (laughable). And since the claim refers to this special mixture having more potential energy than the fuel and acetone independently, for it to work the exhaust gasses exiting the engine would have to be different in some way from a mixture of burnt fuel and acetone, and obviously they won't be. So complete bollocks. :) Rentwa 19:21, 2 September 2006 (UTC)

The third source tries to claim that atomisation (better description than vapourisation) is incomplete and fuel is wasted - not true. Modern engines, especially with engine management systems tend to run at trace knock (lean burn) - no significant unburnt fuel. And since the catalyst is effectively a final combustion chamber, if there was any large amount of unburnt fuel the catalyst would be getting very hot indeed. Finally, molecular vibrations aren't relevant to the discussion on the mixture, polarity is, and I've never heard a real scientist talk about sluggish molecules or 'natural frequencies'. Total bollocks! Rentwa 21:21, 2 September 2006 (UTC)

The acetone thing is an urban legend. Mythbusters even tackled it--it doesn't work. All it will do is damage your paint job if you spill... -- Scientizzle 14:22, 1 September 2006 (UTC)

It would definately hurt your paint job as nail and car paint are very similar. I even tried this, once. (No, not on a car.. ;) RichiH 18:04, 2 September 2006 (UTC)

I can't see how acetone would help; I can see how it would hurt. It's combustion properties are going to be different from gasoline (I can't be bothered to dig out exactly how, at the moment) so it will burn hotter/faster or colder/slower than gasoline. Adding it into the mix in any concentration high enough to have an effect is either going to result in added wear and tear on the engine and increased output of nitrogen oxides (if it burns hotter) or incomplete combustion and increased output of unburned fuel, soot, and carbon monoxide (if it burns colder). Acetone may also attack engine components, as Rentwa notes it will allow water into the fuel, and it will probably harm the finish on the car if spilled. Finally, acetone has a much higher vapour pressure than regular gasoline, resulting in greater losses to atmosphere during filling and increased risks when used in confined spaces. TenOfAllTrades(talk) 15:22, 1 September 2006 (UTC)

Acetone burns faster, thus it should reduce the octane value imho RichiH 18:04, 2 September 2006 (UTC)

If there are plastic parts or hoses which degrade, soften or dissolve in acetone but not in gasoline, you might be in for some expensive repairs. As an analogy, I had a 1970 GM engine which worked great until in the 1980's they started adding alcohol to gasoline. The alcohol ruined the plastic float in the carbureter and required replacement of the carb. And doesn't acetone react with copper? Gasoline is for burning in engines, alcohol is for drinking, and acetone is for removing nail polish. Edison 17:06, 1 September 2006 (UTC)

As Edison shows above, chemicals are used for specific things for a reason. I wish I could explain why acetone is used the way it is, but I've only experienced organic chem for 2 classes so far :/ --Russoc4 20:05, 1 September 2006 (UTC)

genetics

do all the somatic cells in our body have the same sequence of DNA?--hima 13:30, 1 September 2006 (UTC)

In theory they all should since they are all clones. In practice, however, mitosis does not copy with 100% accuracy so there are differences. Add Lyonization and DNA methylation to the mix, you have quite a few differences. InvictaHOG 13:57, 1 September 2006 (UTC)

Also, some people are chimeras, but that's rare. --Allen 03:55, 2 September 2006 (UTC)

Article in Dec 2000 Cleo

I am looking for an article you had in Dec 2000 Cleo titled FLEX by Sam Murphy. It was four pages long and was about exercises for deep abdominal muscles. If there is anyway you could forward me a copy or put it on your website I would be most grateful. Thank you Ruth Kelly, Ireland.

Wikipedia does not publish nor maintain archives of Cleo (magazine), but we have a stub article on it... Perhaps this should be moved to Humanities?Nimur 19:40, 1 September 2006 (UTC)

potentiometer

Q1 principle of potentiometer? Q2 why voltage decreases in the direction of electric field? (please explain in detail) thankyou.

A1 potentiometer / A2 voltage drop ---Sluzzelin 13:58, 1 September 2006 (UTC)

A2 Consider a line through an electric field, with three points on it, A, B, and C. The voltage at A is 2V, at B it is 1 V, and at C it is 0 V.

A-----------B---------C

If an object initially at rest, with a charge of +1 coulomb moves from A to C in an environment with no friction or other impediment, it will acquire kinetic energy of 2 joules by the time it gets to C. On the other hand, if the object starts at B, it will only have 1 joule of kinetic energy when it gets to C. So the voltage at any point in an electric field is a measure of how much energy a charged particle will acquire as it moves through an electric field, and the less of the field it moves through, the less energy it will acquire. --Gerry Ashton 16:32, 1 September 2006 (UTC)

mosquito

what does a mosquito have instead of blood is it hemolymph like all other insects?or anything else?--hima 13:56, 1 September 2006 (UTC)hima

Have a look at mosquito and hemolymph --Light current 14:24, 1 September 2006 (UTC)

Hemolymph redirects to blood or circulatory system. We don't have much of an article on it, just a few sentances in the appriate article. — [Mac Davis] (talk) (Desk|Help me improve)

Petrol additives

Is there anything that can be added to unleaded petrol to improve fuel consumption in a car with an engine management system? — Preceding unsigned comment added by Light current (talk • contribs)

I don't think so. It would be more productive trying to tweak the software I think.

In the UK you can add vegetable oil to your diesel fuel (or run pure veg oil) - veg oil is untaxed so it's cheaper than diesel and works just the same. You can smell cars running on veg oil as they drive past - not a myth at all. Illegal though. Rentwa 14:47, 1 September 2006 (UTC)

Vegoil as fuel is taxed in the UK now: see vegetable oil as fuel. Rmhermen 16:48, 1 September 2006 (UTC)

Motorists have always been liable to pay tax and duty on the fuels they put in their cars. There's nothing illegal about putting veg oil in your car - it's illegal not send a cheque to the chancellor when you do so, which most veg oil drivers don't. Veg oil for sale in the supermarket has no fuel duty or tax added to its price, or housewives would probably be complaining... Rentwa 17:40, 1 September 2006 (UTC)

Most of the additives sold to mix in with your fuel and oil are modern-day snake oil, except in the relatively rare case where your fuel system is genuinely clogged. Subaru recommends the occasional use of an injector cleaner in the fuel of my car, but other cars I've owned have not done so.

One possibility is buying petrol with a partial ethanol blend; it's cheaper in some places because there's no taxes on the ethanol part. But the savings, if any, will be very small.

If you really want to save fuel, make sure you don't carry unnecessary items in the car, make sure your tires are kept inflated to the recommended pressures (or a little above, perhaps to what the manufacturer recommends for heavy loads), and drive smoothly and at sensible speeds. Beyond that, drive a more fuel-efficient car. -Robert Merkel 15:47, 1 September 2006 (UTC)

Could it be my EMS sensors not working correctly?--Light current 15:51, 1 September 2006 (UTC)

In your car I think the problem is less likely to be caused by hardware or software, and more likely to be something to do with the wetware. :D Only kidding :) . Rentwa 18:32, 1 September 2006 (UTC)

Well, additives do reduce gasoline consumption in that they burn themselves, providing some fuel. So, if you add a pint of fuel additive to a tank of fuel, you might reduce the fuel consumption by up to a pint. Thus, they aren't lying when they say their additive "reduces gasoline consumption", they are technically correct. Of course, the cost of the additive greatly exceeds the cost of the saved gasoline, that part they don't tell you. StuRat 00:49, 2 September 2006 (UTC)

World spin

Ive often wondered what originally gave rise to the rotation of the earth and what its rotational energy would be. Any one know?--Light current 15:12, 1 September 2006 (UTC)

I am guessing, but most of the planets rotate in the same direction the Sun does, right? So the theory is they arose from a gout of matter spouting from the sun which condensed into what we have today. They also rotate in the same direction they revolve around the Sun, too, right? 12.41.204.3

Not necessarily. The original nebula from which the Sun formed had angular momentum, and following the prevalent theory of planetary formation, the entire cloud was rotating (perhaps due to the supernova explosion that gave birth to the cloud to begin with), and the planets, as they coalesced by attracting all the objects within their gravitational field and colliding among themselves, maintained that angular momentum. Titoxd^(?!?) 17:02, 1 September 2006 (UTC)

After edit conflict:

As was discussed in a thread a few days ago, Venus and Uranus are the odd ones out when it comes to rotation. The rotational direction of the others makes sense to me in the way the coriolis effect works: material that moved from the outside of the accretion disk towards the inside to become part of the Earth went to a region with slower rotation, so the material that hit the part of the Earth that was pointing away from the Sun moved faster than the Earth and thus gave that side an extra impulse. Material that came from the other side ('from the Sun') was slower and thus slowed that side of the Earth down. DirkvdM 17:17, 1 September 2006 (UTC)

Calculating the rotational energy would require integration, which I'm not good at, so I'll just make an educated estimation. A kg at the equator moves at 40.000 km / 24 h and thus has an an impulse of 40.000.000 m / 80.000 s = 500 kg.m/s. The Earth weighs 6 x 10²⁴kg and assuming that the centre of mass of one side is at about half the radius the total rotational impulse would be 0,5 x 6 x 10²⁴ x 500 = 1500 x 10²⁴ kg.m/s. That's impulse, though, not energy. I'm not a physicist either. :) DirkvdM 17:25, 1 September 2006 (UTC)

Don't forget to include moons and rings when calculating the orbital angular momentum of a planetary system! Nimur 19:36, 1 September 2006 (UTC)

Moons and rings are typically insignificant in mass compared with the planet they orbit. Earth's moon is an exception, being quite large relative to Earth. Pluto, if you still consider it to be a planet, is also an exception, with it's biggest moon, Charon, being even larger relative to Pluto than our moon is to Earth. The mass of everything else in the solar system is also insignificant relative to the Sun. StuRat 20:44, 1 September 2006 (UTC)

Well early earth collided with a "roughly mars sized object" so wouldnt its spin be messed up this anyway? Philc _T^E_C^I 20:56, 1 September 2006 (UTC)

The Giant impact theory? Not necessarily. If the two bodies were rotating on similar planes, they would have a very similar angular momentum unit vector, so when the collision occured, the resulting body would still have the sum of the individual bodies' angular momentum, in a similar direction. Titoxd^(?!?) 06:10, 2 September 2006 (UTC)

I don't think similar planes would do it, they would have to be orbiting in pretty much exactly the same plane, or the off-center collision would tilt the two rotating objects. StuRat 10:32, 2 September 2006 (UTC)

Since they didnt collide core to core, and more of glanced, tearing the smaller in to 2 pieces, one of which then collapsed into the earth, the other settled into orbit after taking a large lump of crust with it. Aglancing hit would mean al of the momentum was transferred onto one side, so would it actually be possible for the spin to be undisturbed. Philc _T^E_C^I 18:58, 2 September 2006 (UTC)

Zoosex

Can for example a cat become pregnant from human sperm and vice versa (a woman from horse)? --Brand спойт 16:55, 1 September 2006 (UTC)

'Can for example a cat become pregnant from human sperm ...' is there something you want to tell us? Rentwa 17:45, 1 September 2006 (UTC)

Unless they contain the same number of chromosomes, no. Titoxd^(?!?) 16:58, 1 September 2006 (UTC)

No. Species must be very similar for such matters to take place (horse and donkey, for example). —Daniel (‽) 17:00, 1 September 2006 (UTC)

Also supposedly lion and tiger. What about primates? Gorilla/chimp/orangutan combinations? Horse/zebra? Edison 17:11, 1 September 2006 (UTC)

Species are defined as being able to interbreed, so if two animals are of different species, they can by definition not interbreed. Btw, if you ask about interbreeding primates, why not take a combination with humans to spice it up a bit? A humanzee? A humilla? With an Orang Utan the naming gets interresting because the word 'orang' is Indonesian for 'human' (and 'hutan' means forest, so it's a 'forest man'). DirkvdM 17:33, 1 September 2006 (UTC)

It's a little more complicated than that. Horses and donkeys are definitely different species, but they can produce offspring, and once in a great while even fertile offspring. Sometimes species are defined as being able to produce offspring that "breed true", whatever that means. I think it needs to be recognized that there is no completely precise biological definition of "species"; like any other level of taxonomy, there are arguable borderline cases. --Trovatore 17:37, 1 September 2006 (UTC)

If it is seperate genuses than no way, as far as I know. — [Mac Davis] (talk) (Desk|Help me improve)

For the record, the plural is "genera", à la generic vs. specific characteristics. Melchoir 18:13, 1 September 2006 (UTC)

Yes there are cross-genera and even cross-family hybrids. See hybrid, the article. Rmhermen 18:48, 1 September 2006 (UTC)

Two separate geniuses have indeed been known to reproduce. Edison 04:51, 2 September 2006 (UTC)

Citric Acid

Would diluted citric acid kill sperm?

Are we still talking about the cat? Rentwa 18:40, 1 September 2006 (UTC)

Ah, but aren't we all, on some level, talking about the cat? Melchoir 18:43, 1 September 2006 (UTC)

I think the cat is really going to dislike you if you introduce citric acid to the sitution. Weregerbil 18:55, 1 September 2006 (UTC)

Would diluted citric acid kill the cat? Until we dump the citric acid on the cat, he is both alive AND dead; we will determine an outcome by dumping acid on him. DO NOT TRY AT HOME Nimur 19:35, 1 September 2006 (UTC)

It probably wouldn't kill the cat, but I bet it would sting the pussy. Rentwa 00:01, 2 September 2006 (UTC)

Oooo it makes your eyes water just to think about it (2 points I think 8-))— Preceding unsigned comment added by Light current (talk • contribs)

This is a surprise to me, but Spermicide actually answers the question. Melchoir 18:44, 1 September 2006 (UTC)

Not talking about the cat (though funny placement. I have good timing.) Thanks!

Err...Part two; would citric acid kill a yeast infection?

Dammit, I can't look at that article. I'm not even going to link to it. Melchoir 19:58, 1 September 2006 (UTC)

Which article do you mean?--Light current 01:59, 2 September 2006 (UTC)

Why not try squeeezing your lemon to find out?--Light current 21:33, 1 September 2006 (UTC)

"Squeeze my lemon, till the juice runs down my legs". DirkvdM 09:19, 2 September 2006 (UTC)

Moon moons ?

Does any moon have it's own natural satellites ? I would expect they would, unless tidal forces from the planet would cause their orbits to be unstable.

If there are examples of moon moons, how about moon moon moons, etc. ? (Has the word lost all meaning yet ?) :-) StuRat 20:49, 1 September 2006 (UTC)

Wouldnt any moon moons be pulled out of their orbit when they get to close to the planet of the moon they are orbiting, as relative to their sizes, planets are alot closer to their moons, than the sun is to its.

Hmm... isn't that what happens at a Lagrange point? And it sounds a bit like something the L5 Society would like to know. Titoxd^(?!?) 20:57, 1 September 2006 (UTC)

Do you consider 3:2 orbital resonance to be a "moon"? (Earth's "second moon" is 3753 Cruithne, which is not really a moon but has a 1:1 resonance.) Then Pluto would be a moon of Neptune, and then Nix and Hydra are "moon moons". —AySz88\^-^ 21:08, 1 September 2006 (UTC)

It would be extremely unlikely that any moon would have its own moons. Any such orbits would be extremely unstable with all the bodies as close together as they are in a solar system. Over larger distances it's certainly possible, although the bodies get a lot bigger. The Sun orbits the centre of the galaxy, the Earth orbits the Sun and the Moon orbits the Earth. Why this system works is probably best explained by the anthropic principle. An alternative explanation would take a very long time to give.

I think if you have too many generations of moons, you may end up with an ustable chaotic system that would eventually chause some of thes objects to coalesce.--Light current 14:51, 2 September 2006 (UTC)

---

What conditions would be needed to have a stable moon moon ? Perhaps a huge planet/failed star at an extreme distance (say 40 AU) from the main star could have a moon at an extreme distance from it (say 1 AU), and a moon moon around it that would be stable (being far enough away from gravitational tidal forces of the planet and star) ? StuRat 00:34, 2 September 2006 (UTC)

Although I don't know of any, I don't see why in theory moons can't have moons. After all, our moon has over the past half century had probably hundreds of "artificial satellites" orbitting it. Though these artificial satellites have generally, deliberately ended there missions by having their orbits decay, eventually crashing into the moon, surely there must be at least some space junk orbitting the moon at this time in an orbit with the potential to carry on indefinitely. This may be "space junk", but if it exists, in theory at least, it would seem to qualify as a "moon" orbitting the "moon". Loomis 04:24, 2 September 2006 (UTC)

Isn't that a matter of mass? An artificial satelite can do it, so why not a natural one? How this would be formed is a differnt matter. I don't think you would get such a moon from the same planetary accretion disk, so it would have to be caught. Probably the chances of that producing a stable orbit are very small, but in an immense Universe that's all you need. DirkvdM 09:28, 2 September 2006 (UTC)

In theory moons can have moons. The problem is that the orbits will (almost) certainly be unstable over long time periods due to the number of forces acting on them (they would certainly be unstable if they existed for an infinite time). It is possible (although highly unlikely) that (taking our moon as an example) our moon could trap a body to behave as its own satellite, but it would only stay there for a very short time and, if it did happen, we weren't around to see it. Artificial satellites have the same problem of stability. The articles on chaos and the n-body problem should be relevant to this (assuming they're well written).

Moons can have artificial satellites, such as the Apollo Command/Service Module during the manned moon missions. Nimur 13:03, 2 September 2006 (UTC)

Just to qualify everything... in the approximation that the moon's orbit is circular, then you can prove mathematically that certain orbits around the moon are stable, since they are completely encircled by the zero-velocity curves of their Jacobi integral. Such protective curves go all the way out to the nearest Lagrange points. So you don't have to worry about the planet pulling the particle away from the moon.

What you do have to worry about is the possibility that, if you wait long enough, the particle might crash into the moon. There is no mathematical barrier to such a crash, as there is in the two-body problem (the centrifugal barrier). In some sense the real question is, how long should it take for such a crash to occur? And I seriously doubt there's a known analytic answer to that one; you'd have to break out a numerical simulation, plug in your desired mass ratio and moon radius, and see. Melchoir 17:23, 2 September 2006 (UTC)

I could always moon the Moon. Would that help? Clarityfiend 04:37, 3 September 2006 (UTC)

And then let someone else drop their pants and run in circles around you. Problem solved. QEI (quod erat inquisitum). DirkvdM 05:36, 3 September 2006 (UTC)

Private Hospitals in Altanta, Georgia in existence 1967

Trying to locate nurse who worked in expensive private hospital, Coronary Care Division in Atlanta, Ga. in 1967. Hospital could place instrument for heart (cost $2,000) on arm in case of heart failure. Feel this fairly new concept at time. Hospital's name wanted. Help,please!

How about Emory University hospital? InvictaHOG 21:24, 1 September 2006 (UTC)

Free software to make contour maps from spot heights?

Is there any please? There is a pay-for program called Surfer, but it costs over $500. 62.253.44.32 23:36, 1 September 2006 (UTC)

Given an XY grid of points, where the Z coord is given for each, it seems like quite a simple program could create a contour map. Given points not on a grid, it would be a bit trickier. Also note that a general 3D CAD system could do this, by running a surface thru a point cloud, then intersecting that surface with planes parallel to the XY plane. StuRat 00:23, 2 September 2006 (UTC)

Wouldnt it be grossly inaccurate due to the fact that the ground is not flat planes between spotheights, something that a program designed for this would probably take into account. Philc _T^E_C^I 00:33, 2 September 2006 (UTC)

The simplest program could just do a linear interpolation between grid points, to find contour line/grid line intersection points, then draw straight lines between those. For example, given grid point elevations of 4, 6, 7, 1, 2, and 4, a contour line could be drawn at an elevation of 5:

4 . . . . . * . . . . . 6 . . . . . . . . . . . 7
. . . . . . . . * . . . . . . . . . . . . . . . .
. . . . . . . . . . * . . . . . . . . . . . . . .
. . . . . . . . . . . . * . . . . . . . . . . . .
. . . . . . . . . . . . . . * . . . . . . . . . .
. . . . . . . . . . . . . . . . * . . . . . . . .
. . . . . . . . . . . . . . . . . . * . . . . . .
. . . . . . . . . . . . . . . . . . . . . * . . .
. . . . . . . . . . . . . . . . . . . . . . . . *
. . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . 
1 . . . . . . . . . . . 2 . . . . . . . . . . . 4

StuRat 03:27, 2 September 2006 (UTC)

R is free and can make contour maps, I'm pretty sure. I don't know fancy the graphics get, though. --Allen 03:46, 2 September 2006 (UTC)

Gnuplot can produce contour plots. – b_jonas 10:42, 2 September 2006 (UTC) (Update: I mean if the samples form a grid. – b_jonas 10:43, 2 September 2006 (UTC))

Thanks, but unfortunately my data does not form a grid.

If the data is not already in a grid, the first task of any program would be to establish a grid, a process called tesselation. Then you could do the same linear approximation discussed previously, from there. However, if you only have a low number of sample points, the resulting contour plot will be highly inaccurate. StuRat 03:06, 3 September 2006 (UTC)

September 2

Self CPR

I'm taking a final exam for an online class and one of the questions I have to answer is whether self CPR is fact or fiction.

Perhaps you could think about this for a few seconds. BenC7 01:58, 2 September 2006 (UTC)

If you are unconcious how would you do it?--Light current 02:03, 2 September 2006 (UTC)

There is a procedure to help yourself when you are choking where you hold your fists just south of your thorax and run into a wall with your head held back (I Canada you usually learn that as an aside on your way to becoming a life-guard). Maybe something similar could work for when your heart stops, though I think the chance of your heart stopping and you knowing while being concious are pretty much zero. Then there's the fact that manual CPR usually only works after repeated applications, which means you'd be running into the wall a lot.  freshofftheufoΓΛĿЌ  06:27, 2 September 2006 (UTC)

...That is a procedure in Canada? Can I PLEASE see it on tape or something? If I didn't suspect it would hurt like a bum, I'd try it out. Sounds difficult to run onto things like that. Henning 08:26, 2 September 2006 (UTC)

Haha, I've never actually seen it done. My instructor just explained how it could be done if you were ever caught by yourself with a chicken bone stuck in your throat.  freshofftheufoΓΛĿЌ  15:57, 2 September 2006 (UTC)

Fiction. If you have no pulse and no respirations, you are unconscious and unable to do CPR. InvictaHOG 09:32, 2 September 2006 (UTC)

Which leads me to think, are you sure it's "self CPR" and not "self Heimlich-maneuver" or something? Just a thought. CptJoker 01:22, 3 September 2006 (UTC)

5 or 10 years ago there was a story which made the rounds of print media and internet that if one suddenly realized his heart had stopped, he could do self cpr by coughing vigorously, and get enough blood to circulate to maintain consciousness long enough to summon help or dial 911. A while letaer Red Crosss officials denied it was true. Could one realize the heart had stopped and still have consciousness for a bit? Why not? Edison 20:31, 2 September 2006 (UTC)

That's not to be done if your heart stops, it's taught in MedSchool if you go into VF. If you cough, at least some blood gets moved around cos the valves keep doin' what they're doin' despite zero cardiac output from ventricles. ≈Eh-Steve 21:02, 2 September 2006 (UTC)

Viral Marketing

I'm rather worried by the note at the bottom of the Factotum article. I wandered through the history, and apparently on 3 August, an anonymous person added what looked like a full-page advertisement for the film. On 23 August, another anonymous person removed it, leaving a rather cryptic note with a link to the viral marketing article. To be honest, I've been wondering for awhile just how much people could potentially take advantage of Wikipedia for monetary gain. Does it sound to you like that's what was happening? Black Carrot 02:16, 2 September 2006 (UTC)

Yes, it's absolutely a problem with a medium like Wikipedia. A simple example would be all the neologisms that people try to get added, thus increasing awareness about the unknown word in the hopes that somebody will actually get tricked into using it in an AOL chat session. Most of those get caught pretty easily, but I imagine it's much more difficult to pick things like that out of articles with corporate connections so who knows how much if it actually gets through.  freshofftheufoΓΛĿЌ  06:33, 2 September 2006 (UTC)

When was redial invented?

I've been searching all over the Internet and I can't find the date that redial was invented. What I really want to know is, would telephones in 1990 have automatic redial buttons, and, if not, what would they have? Please help. 88.105.159.129 10:12, 2 September 2006 (UTC)

I would guess that was available on the first touch-tone phones. Dial phones did not normally have that feature. StuRat 10:24, 2 September 2006 (UTC)

True, but they had a line to the operator, who could probably redial for you--71.247.243.173 13:44, 2 September 2006 (UTC)

That would be a serious pain in the neck in comparison with just a simple button. --Fastfission 15:46, 2 September 2006 (UTC)

Ah, so it's been around since the sixties then. Thank you! 88.105.159.129 10:36, 2 September 2006 (UTC)

They've definitely been around since 1990. I can remember them from the even the very old (and crummy) phones from that time. --Fastfission 15:46, 2 September 2006 (UTC)

I have seen rotary phones with a redial function before. It's almost rediculously complex, and it seemed to take a while to actually dial the number (it of course has to mechanically spin the dial). I can't say when it was actually invented though, or if the touch-tone version came first.  freshofftheufoΓΛĿЌ  15:55, 2 September 2006 (UTC)

Yea, I see no reason why it wouldn't be possible on a rotary phone, but it does seem like an ugly bit of machinery would have been required, making it easier to just manually redial. An analog audio tape of the clicks could also be recorded then played back. A hybrid would also have been briefly possible, where the clicks were captured digitally and played back electronically. Of course, once that technology was available, why not just upgrade to a touch-tone phone, instead ? StuRat 22:13, 2 September 2006 (UTC)

Karl von Goebel

Why is Karl von Goebel sometimes known as Karl Ritter von Goebel and others as Karl Immanuel Eberhard von Goebel ? — Dunc|☺ 11:02, 2 September 2006 (UTC)

Check out Ritter. It is a title of nobility that can be added or not according to the author's preferences. Same goes for Karl von Goebel vs Karl Immanuel Eberhard von Goebel; it depends on context, space, and preferences. George W. Bush is sometimes referred to as George Bush or George Walker Bush or Dubya and Brian Eno is sometimes referred to as Brian Peter George St. Jean le Baptiste de la Salle Eno :). ---Sluzzelin 11:34, 2 September 2006 (UTC)

refrigerator vs. environment

Can a refrigerator operate successfully in an unheated garage in winter where the temperature falls below freezing?

• Why not? Don't most firdges have an internal thermostat? in which case, it would read the temperature as below 0^oC and woudln't need to do anything (: 71.247.243.173 13:43, 2 September 2006 (UTC)

• if contents of a refrigerator spoil when power is cut off when the environment is warm ...obviously the fridge is not 100% insulated....therefore, if the fridge senses the outside temp. as freezing and doesn't do anything...wouldnt the contents eventually freeze? I am referring to a fridge...not a freezer.

There's no such thing as below zero ;). My guess would be that unless you had a fridge which had the ability to warm, then prolonged exposure to below zero would cause the contents to freeze. Hell, my fridge freezes everything in sight, and it has never seen temps below zero! --liquidGhoul 14:04, 2 September 2006 (UTC)

It gets colder than -20 C in the winter where I'm from, and the answer is a pretty obvious yes, if you go away on a ski trip for a few days and turn off all the power, all of the food in your fridge will freeze.  freshofftheufoΓΛĿЌ  15:51, 2 September 2006 (UTC)

Soft drink machines are commonly outdoors in states where it gets to -20 F in the winter. I expect they have internal heaters to keep the contents from freezing. In an ordinary refrigerator, in an unheated garage, if the air got below 32 F for an extended perion the contents would certainly freeze. A little ingenuity could install an auxiliary thermostat inside to turn on the light bulb or a light bulb when the temperature in the fridge got down to 32 f. The deadband would have to be precise, so the light/heater would go off at a temperature below the one where the cooling unit went on, and contrariwise. For instance, the cooler goes on at a rise to 40 degrees and off at a drop to 37 degrees. The light bulb or heater goes on at a drop to 33 degrees and off at a rise to 35 degrees. See the problem? You could wind up with the heater on fighting the cooler. Edison 20:39, 2 September 2006 (UTC)

If you had a small electric space heater, with a thermostat that goes down to freezing, you could put that in the fridge when it gets cold. Do they sell such heaters to keep pipes from freezing ? StuRat 22:00, 2 September 2006 (UTC)

Seminar report

We have a weekly semianr to be given on any of the technological advancement aorund us. I have decided to give a seminar on the RADAR JAMMERS.

I was looking forward for some good materials so as to produce a good report. I have found a few but would like to get into the core of the subject for self interest.

Would be looking forward for help from any of u.. Thanks Saket--220.227.48.17 13:36, 2 September 2006 (UTC)

Doesn't it make sense for you to choose to give a seminar about something on which you are knowledgable, rather than just relying on the nice people at Wikipedia? —Daniel (‽)

electronic attack. Xcomradex 15:30, 2 September 2006 (UTC)

Memory Metal for Cars?

How strong are memory metals? Could you theoretically build the outside of a car from one, and then, after an accident heat it up and have it regain its former shape?

Thanks, —Daniel (‽) 14:43, 2 September 2006 (UTC)

I know this but I cant remember! I need to shape up I know 8-)--Light current 15:51, 2 September 2006 (UTC)

I don't understand why it's so expensive to replace a car body panel. They should be dirt cheap, as they're stamped by the thousand. Perhaps we need a change in the structure of auto sales, where the car company leases cars for a few months at a time. Then, when they get a dented car back, they would have an incentive to replace the body panel cheaply, so it could be released. At present, they don't seem to have any incentive to make repairs inexpensive, as that just prevents people from buying new cars. StuRat 21:53, 2 September 2006 (UTC)

A great question! BenC7 04:09, 3 September 2006 (UTC)

The price could have someting to do with labour intensity. The panel seems expensive compared to the car, but it's really the cars that are dirt cheap for the sort of product you get, due to mass production. Repair work isn't mass production, so it's relatively expensive. Maybe if you could buy the panel and then replace it yourself. But then there would have to be a distribution network for loose parts, and the per piece price would probably far exceed the production cost. Your solution would solve the latter problem, but not the former. DirkvdM 05:59, 3 September 2006 (UTC)

There is also the possibility of plastic car exteriors, which I believe would be easier to 'de-dent' and would also be lighter and therefore more fuel efficient. This already exists, but my guess it isn't popular because plastic can't be made as shiny as metal. DirkvdM 06:01, 3 September 2006 (UTC)

Special relativity

So, I've been reading into Photon, Special Relativity and more, and I have come to be frustrated, very at that, at not understanding the topic.

I realize very well that there is a particle-wave duality to photons, it's their speed I can't understand. If I travel on a pimped up spacecraft with neon lights all over, and overtake another spacecraft, I will measure the speed of HIS light as C, even though I am travelling at +V away from him and his light?

Oh, and I have a second question, way better! Is there any book like... Relativity/Quantum dynamics For Dummies, which actually explains everything? Everything with a capital E, that is polarization, QED, string theory, t... everything? Many thanks in advance. 81.93.102.35 14:59, 2 September 2006 (UTC)

(I am not qualified to answer, don't get annoyed at me) As far as I know, you are right. Whatever speed you are traveling towards/away from each other, you will still see the speed of light in a vacuum at the same. This, I think, arises from some weird curvature of spacetime. —Daniel (‽) 15:22, 2 September 2006 (UTC)

THe way I tend to think of it is that light can only travel at one speed (in vacuum). THis speed cannot be changed as it is a function of the fundamental properties of space. So, whenever you try to measure the speed, you always get the same answer. What you will see, however, is a red shift if you are travelling away from the light source and a blue shift if travelling towards it. Is this helpful?--Light current 15:40, 2 September 2006 (UTC)

Though the "...for Dummies" franchise doesn't seem to have given it a shot yet, this google search might help you find the same sort of introductions.  freshofftheufoΓΛĿЌ  15:48, 2 September 2006 (UTC)

List of ...for Dummies books does mention Einstein for Dummies! Until you get the book you can also try more googling, the first hit looks like something I'm going to go and read right now. Weregerbil 16:07, 2 September 2006 (UTC)

For future reference: Most of the parameters in a Google URL are unnecessary (and possibly undesirable for a user whose cookie has unusual preferences); all you really need is the "q=". Weregerbil gets it right. —Tamfang 18:26, 2 September 2006 (UTC)

'Moving' source, 'stationary' observer

Look at it this way. Assume you are 'stationary', and something is receding from you shining its light at you. When the light on the distant object leaves the lamp, the light doesnt know that the lamp is travelling backwards at high velocity. All it knows is that it has been launched into space and is therfore compelled to travel at the universal velocity 'c'. When you measure its spedd you find its 'c' also. Any clearer?--Light current 15:49, 2 September 2006 (UTC)

'Stationary' source, 'moving' observer

Essentially the same as above. THe source transmits the light at 'c'. Although you are moving backwards at high velocity, the light doesnt know this and doesnt care. When it reaches you, red shifted, you still measure its velocity as 'c'--Light current 16:16, 2 September 2006 (UTC)

An easier answer (or so I hope)

Ok, you're watching another spaceship full of neon lights and you're observing it's light. You're travelling away from the other ship with a velocity of V or something of the like, something pretty fast. The other ship will fall behind you pretty fast. But if you phone the guys in the ship, they'll tell you: "We aren't moving, it's you that's going away." Well, that's just a different point of view, you see? Nothing special. Velocities just seem to be different when you're moving.

Except the one of light. The guys in the other space ship aren't moving (or so they think), so when they observe their neon lamps, they'll see light coming out with a velocity of c. When you are observing this same light being in the other ship, you'll see the same velocity relative to your own position. That may seem weird – you'd think it should be c+V or c-V or something of the like. But it doesn't work that way.

To relate your observation with their observation, you need Lorentz transformation. This means that space and time are related to each other in a way which is slightly more complicated than how you'd think they are. Velocity being space divided by time, it gets quite more complicated than c+V. But the result is just c.

Hopefully this helps. David 16:42, 2 September 2006 (UTC)

But surely the Lorenz transformation is a consequence of the invariance of the speed of light, and not the other way round? So the answer should be able to be given without bringing in Lorenz? 8-|--Light current 17:55, 2 September 2006 (UTC)

Thank you for clearing this up for me. I am in the process of reading that -- for Dummies-thing, it should work wonders. :) 81.93.102.35 18:10, 2 September 2006 (UTC)

Good page: Velocity_addition_formula--Light current 18:11, 2 September 2006 (UTC)

I know that according to the Michaelson/Morely experiment, there isn't any detectable change of speed of light in any direction, so there is no basis for an ether to exist. Still, have anyone tried accelerating something in vacuum? I don't know how realistic it is to assume that this can make any difference - I just wondered if it is certain that nothing spends more time or energy accelerating into one direction than into another. 81.93.102.35 19:27, 2 September 2006 (UTC)

Infinitly improbable events in infinite time

In an infinate amount of time, the probability of any event happening which has a probability not equal to zero is 1. So in infinite time every event even with a miniscule probability of say the inverse of a googel to the power of a googel, will definitely happen.

So even after I'm dead, by random chance something resembling my brain with the same thoughts and memories as I have now must eventually come into existence, not only once but many times. And I could also have the same kind of body, the same kind of society even. In other words I (and you) should be resaurected (sp?) many times, if the universe lasts an infinite length of time.

Can anyone point out a logical flaw in the above argument please? For example, will the universe last an infinite amount of time?

The universe (as we know it Jim) will not last an infinite time.--Light current 17:57, 2 September 2006 (UTC)

Although assuming our universe could last for an infinate time, i don't see any flaws in your argument. Benbread 17:58, 2 September 2006 (UTC)

In case anyone hasn't seen it: Kolmogorov's zero-one law. Melchoir 18:03, 2 September 2006 (UTC)

Many events (as humans perceive them) that do occur do not simply have miniscule probablity, they actually have probability of exactly 0. If the probability of an event is 0, then even given infinite time, then you might still observe that it happens never, only once, or many times. Consider a dart board and a dart. The dart board has some finite area. The dart has a much smaller, but still finite cross-section; however one can think about the center point of the dart: some mathematical point that defines the true center of where the dart strikes. Such a point has no area, being just a point. Throw the dart at the board and you know that some point will be selected in this way, but there are an infinite number of choices and each time you select only one center point of the dart. Hence the probability of selecting any particular point is 1/infinity which is exactly equal to 0. And yet you can perform the action and know each time with certainty that some point will be selected. Further, an event with a probability of 1/infinity, given an infinite number of trials, need not be expected to occur, because infinities come in different degrees, countable and uncountable. By definition any repetitive action performed an infinite number of times belong to the countable class of inifinities because you can enumerate each trial (1, 2, 3, 4, etc.). However, it can be proven that you could never enumerate all the points on a dart board, no matter how clever your scheme might be, there are simply vastly more than could ever be described by the set of all numbers 1, 2, 3... This is non-intuitive, I know, but in many situations there are simply more possible outcomes then one could possibly precisely enumerate, even given infinite time to do so. I supsect that most of what occurs, from the effects of a single storm to the evolution of the human race, are like throwing darts at a board. A particular event occurs from an infinitely rich set of possibly variation, but each possibility had an intrinsic probability of zero. If that is the case, then the probability of you, me, or the human race ever having occurred is zero and even given infinite time should not be expected to recur. Dragons flight 18:37, 2 September 2006 (UTC)

Dragons flight chose his words carefully, I want to point it out. If that is the case, then the probability of you, me, or the human race ever having occurred is zero and even given infinite time should not be expected to recur. That's, of course, not to say that it couldn't recur, just it isn't expected. Probabilities become very hard to understand intuitively when the number of trials is infinite. So, for any event with probability zero, it could happen any finite number of times in an infinite number of trials. With respect to your question if you assign the event that someone again has exactly the same thoughts as you a positive (non-zero) probability, then the probability it occurs again given an infinite number of trials, is 1.(*) However, if such an event has probability 0, given an infinite number of trials it might happen again, but it need not. (*: This is so long as each individual trial is independent) --best, kevin [kzollman][talk] 20:51, 2 September 2006 (UTC)

It is probably theoretically possible for something to have, say 1/4 probability of ever happening given infinite time (if I have this right). Imagine that, starting now, for some x amount of time, an event has a 1/5 probability of happening within that time. After that x amount of time, then for the next x amount of time, it has a 1/25 probability of happening. Then it has a 1/125 chance, then 1/625, etc. This goes on infinitely. The sum of all those is not one (or infinity) but 1/4 (see geometric series - scroll down that page) - not one or zero.

(I know the numbers don't sum up that way - the 1/25 ends up being 1/25 of the remaining slice, not 1/25 of the total slice - but explaining all that would detract too much from the point.) —AySz88\^-^ 18:58, 2 September 2006 (UTC)

You have to remember that not all possible paths lead to all possible outcomes, when sonthings happens in the universe, it always cuts out the possibility of a an infinite number of alternative possibilities from ever happening. So basically, if the human race became extinct tomorrow, even if the universe existed for eternity, the possibility of someone exactly the same as you having the same thoughts as you is 0. Philc _T^E_C^I 19:32, 2 September 2006 (UTC)

Schroedinger's cat?--Light current 20:19, 2 September 2006 (UTC)

I'm afraid I don't see how this is related. --best, kevin [kzollman][talk] 20:51, 2 September 2006 (UTC)

As a bit of nit-picking, there is no such thing as "infinitely improbable" in the standard real number system. Something either has probability 0 or a positive probability. In order to have "infinitely improbable" one must introduce infinitesimals which results in a different theory of probability than is standardly used. --best, kevin [kzollman][talk] 20:51, 2 September 2006 (UTC)

See Infinite_monkey_theorem for an example of a finite, but highly improbable, event that would occur, given an infinite number of trials. StuRat 21:33, 2 September 2006 (UTC)

What do you think we're doing here?9-)--Light current 21:36, 2 September 2006 (UTC)

Except that we're not nearly as intelligent as the monkeys. :-) StuRat 21:42, 2 September 2006 (UTC)

Yeah, they got it made eating bananas, screwing round all day.... Hey hang on a minute- sounds familiar!--Light current 23:33, 2 September 2006 (UTC)

The formation of life on Earth may be similar. That is, it may be a highly improbably event, but, given all the planets and moons around all the stars, in all the galaxies in the universe, even highly improbable events become quite likely, somewhere. Then the not-too-bright say "but what was the chance it would have happened on the planet where we live ?". Well, the chance that life had evolved on any planet where life currently exists is actually quite good. StuRat 21:42, 2 September 2006 (UTC)

The flaw in the argument is that Kolmogorov et al are applying ideas from Pure Maths to Applied Maths (and then to Real Life). Things tending to particular limits as other things tend to infinity only means something in some very specific Pure Maths situations - to apply these processes to Applied Maths which is talking about real life is silly. Thats the flaw.

And since we're talking about real life I can postulate that the monkeys instead produce an infinite amount of garbage, or the atoms will come to resemble a donkey's thing, and you can't point to any real life cause which will necessitate that they do otherwise. Rentwa 22:31, 2 September 2006 (UTC)

What is zero multiplied by infinity? If you can do this, you have the answer.--Light current 22:35, 2 September 2006 (UTC)

Not defined by arithmetic, zero if calculated according to limits. Rentwa 22:40, 2 September 2006 (UTC)

It could be anything, calculated according to limits. For instance, lim(x->0) x(1/x)=1, x(2/x)=2, x²(1/x)=inf etc. If I may, though, I see some things that don't make sense to me. First, what does it mean to say that an event, like someone with a particular genetic code being born perhaps, has a particular "probability"? Or sentient life springing up, or whatever. The universe, above the quantum level, is as predetermined as clockwork. It's not a matter of manipulating random variables to get the answer, it's a matter of manipulating very very definite equations of physical motion. For instance, let's say we find the "probability" of a 2kg mass being pushed with 1N of force for 1s, but inexplicably gaining several thousand m/s of velocity. This would have a probability zero. Hitting a theoretical point with a theoretical dart has a probability "almost zero", meaning it could conceivably happen but almost certainly won't any time soon, but this just plain won't happen, ever. Am I right? So, it's not a question of whether a universe filled with random static could ever clear up for a moment into a universe with human life, it's a question of whether this universe, given its starting conditions and laws, will ever do so. Which it probably won't ever again, if the heat death theory is to be believed. The only thing that brings randomness into it is Schrodinger's cat, as someone earlier said, which is a demonstration of the link between the alleged pure randomness of the quantum world and normal events. Even given that, though, I doubt the question changes much.

BTW, something that crossed my mind, rereading the original question - If someone with your thoughts and memories were to show up later, given the strong link between thoughts and the reality that made them, that would suggest that the entire universe was on some sort of periodic cycle, wouldn't it? If the same things happened again, they would surely lead to the same results again, and therefore back to themselves again, ad infinitum. Only a universe where cause and effect weren't so closely linked, as in the imaginary random universe you're working with, could that not be the case. Black Carrot 23:15, 2 September 2006 (UTC)

Given multiplication of m by n is defined as adding n lots of m, 0 times infinity is the sum 0 + 0 +...+ 0 = 0 as the number of 0's tends to infinity, and it's trivial to prove lim = 0.

I've no idea what you're talking about :) . But you write very nicely. :) Very cool red sig btw. Rentwa 23:35, 2 September 2006 (UTC)

Are you familiar with the idea of a limit? Basically, it says that given a mathematical statement, we can get an idea how it behaves in a particular area by looking nearby.(Edit:Sorry, I just noticed you're the same guy as before.) The sum of an infinite amount of nothing certainly is nothing (stated I believe as $\lim _{x\to \infty }\sum _{a=1}^{x}0=0$ or as 0+0+...+0=0 or as $\lim _{x\to \infty }0x=0$). It'll certainly never get bigger. However, take the function f(x)=x(1/x), which for x=1/5 for instance means (1/5 + 1/5 + 1/5 + 1/5 + 1/5) or (1/5)5. What does f(0)=0(1/0) mean? Well, at every point except x=0, this simplifies to f(x)=1, which suggests that f(0)=1 as well. But, on the other hand, g(x)=1/x gets arbitrarily large (as big as you want, then bigger) as x gets closer to 0, so g(0)=infinity, so f(0)=0(infinity). So, in two slightly different interpretations of 0 times infinity, it's reasonable to arrive at two very different answers, which is why arithmetic doesn't touch it. And thank you. Black Carrot 04:12, 3 September 2006 (UTC)

Iron

What do you get when you mix oxygen with iron? 64.12.116.74 20:06, 2 September 2006 (UTC)

I'd like to help you out, but my chemistry is rusty. ---Sluzzelin 20:08, 2 September 2006 (UTC)

Ha Ha. I think you could get a lot of things (one of upto sixteen different oxides) depending on how you did it. But see iron, Iron oxide, ferric oxide to start.--Light current 20:11, 2 September 2006 (UTC)

Hehe, sluzzelin, it depends though, on temperature and for how long, but if given enough time and or heat, you will get the iron oxides light current mentioned. Philc _T^E_C^I 20:53, 2 September 2006 (UTC)

I prefer to call it "ironic oxide", since you work hard to replace your rusty old car with a shiny new car, then it turns to rust as you work hard for the next shiny new car, etc. :-) StuRat 21:25, 2 September 2006 (UTC)

Quite simple

Dirk vs. StuRat? ≈Eh-Steve 21:08, 2 September 2006 (UTC)

Hmmmm... --Russoc4 02:02, 3 September 2006 (UTC)

But to make it a fair fight, you must use both our full screen names, so DirkvdM vs StuRat. StuRat 02:18, 3 September 2006 (UTC)

Im far too common to enter such a contest!--Light current 02:44, 3 September 2006 (UTC)

Are we being pitted against each other? As if we need the incentive of others for that. And which one is supposed to be "quite simple"? Anyway, there appear to be many StuRats. For example, is this you? If we limit this to Wikipdia we get StuRat 538 vs DirkvdM 886. But t distinguish between us without limiting the search to Wikipedia we could use our real names. here's mine: Dirk van der Made, with a score of 1270. DirkvdM 06:26, 3 September 2006 (UTC)

Northern Cadinal question

There was a fledgling cardinal in our yard about 2 weeks ago--it didn't look like a cardinal, but it was being fed by cardinal parents, and it couldn't fly. We were worried about it because it kept hopping into dangerous areas, like the sidewalk, etc. Now there is a red male cardinal hanging around, but no parents. Is it possible this is the fledgling? How long does it take a fledgling to get its red feathers?

Thanks!

This is a rather entertaining story until you realise it's about birds. :) DirkvdM 06:28, 3 September 2006 (UTC)

sun slowing down

i know the moon is slowly nicking the earths angualr momentum, so does in theory the planets takie angular momentum from the sun? if so, excluding events like sun turning into a red gaint (or the IAU decides to change definition of a planet again)how long would it take with the current planets to stop the sun spinning?--Colsmeghead 23:01, 2 September 2006 (UTC)

• Not sure, but since the Sun is almost 1.98×10³⁰ kilograms, and even Jupiter being a mere 1.90x10²⁷ kilograms, the combined mass of all the planets and other objects in the solar system, probably aren't enough to actually cut into the Sun's angular momentum, at least not in a way that will have a significant effect within the life time of the solar system--71.247.243.173 00:06, 3 September 2006 (UTC)

That's only 1/1000th of the sun's mass... sure it's small, but is it really negligible? Aaadddaaammm 01:14, 3 September 2006 (UTC)

It's the tides that cause Earth to lose angular momentum. Using this formula, I calculated the tidal forces that the planets exert on the Sun:

Mercury: 3.140135 x 10²⁰ N

Venus: 7.104643 x 10²⁰ N

Earth: 3.300665 x 10²⁰ N

Mars: 1.001771 x 10¹⁹ N

Jupiter: 7.446589 x 10²⁰ N

Saturn: 3.619013 x 10¹⁹ N

Uranus: 6.786093 x 10¹⁷ N

Neptune: 2.072556 x 10¹⁷ N

So if Jupiter and Venus are at a 90-degree angle with respect to the Sun, their tides will cancel each other. If there's a syzygy involving Mercury, Earth, and the Sun, and if Venus (or Jupiter) is at a right angle to Mercury, then Mercury and Earth's combined tide will almost cancel that of Venus/Jupiter. Also, if Mercury is at a right angle to Earth, their tides will cancel.

As you can see, the situation is very complex when there's 8 planets involved. With the planets cancelling and overpowering each other's tides, we probably need to run a computer simulation to find out what happens. But even if the Sun is losing angular momentum, it won't stop rotating. I'll use Earth as an example to explain why: the Moon's gravity changes the shape of the Earth, slowing Earth's rotation and in the meantime lengthening the Moon's orbital period. When the length of an Earth day is equal to the Moon's orbital period, Earth's shape will not change anymore, because the Moon will be stationary relative to our planet. When this happens, the length of a day will be fixed forever. --Bowlhover 05:38, 3 September 2006 (UTC)

But, as you say, the solar system is more complex, with all its planets and planetoids and what have you. I wonder if all planets, through their mutual attraction would in the end become stationary relative to each other. But since a given orbit period corresponds to a given orbital radius, all planets would have to merge for this to happen. Is that a state the solar system is moving towards? DirkvdM 06:37, 3 September 2006 (UTC)

No, the planets don't have any reason to merge. The force that the planets exert on each other is very small, certainly not enough to change the planets' orbits to any extreme degree. --Bowlhover 06:54, 3 September 2006 (UTC)

September 3

Genetic Engineering's impact on Plant Biodiversity

What are the impacts of Genetic Engineering on Plant Biodiversity? I know a bit and have already looked at http://www.biotech-monitor.nl/2805.htm and a couple of wiki articles.

Cheers

Basically, as people engineer plants so that they are more profitable/healthy/etc (desirable), the biodiversity goes down because the undesirable plants get unpropagated. When a disease hits that is very detrimental to a certain genome, like the desirable genome, then all those plants die. Without other genomes readily accessible, it is hard to replant. In theory, if we all converted to the most desirable genome, and then it died, well there'd be no more of that type of plant. M.manary 00:12, 3 September 2006 (UTC)

but none of those effects are specific to genetic enginering, if we all switched to one non-gm type of plant we'd go down the same road. Xcomradex 00:19, 3 September 2006 (UTC)

surely introducing wierd and wonderful genes into plants, at least in the short term, increases the biodiversity of plants? You're creating a new species. Whether this species has an effect on others to effect biodiversity, who knows?! Aaadddaaammm 01:13, 3 September 2006 (UTC)

Transgenesis does not, in itself, create a new species. Most genetic engineering of plants for commerical purposes, can be thought of as simply a way of accelerating the same changes that could potentially be brought about by many, many years of selective breeding. The modern farming methods that grow the GM plants may well decrease biodiversity, but the process of genetic engineering - transgenesis - itself is surely increasing biodiversity. Rockpocket 01:56, 3 September 2006 (UTC)

Interstellar travel

Let's assume we can aim a spacecraft in the direction of a star (or rather, where the star will be when the spacecraft gets there), fire the thrusters, and have it arrive within 15 AU of the star without any further navigation. Under this unrealistic assumption, and using current technology, is it possible to:

1. Use RTGs to aim the spacecraft at Alpha Centauri and fire the thrusters.
2. Shut the spacecraft down.
3. When the spacecraft is very close to the star, have its solar panels generate enough energy to power a light bulb.

If this is possible, is it possible to send a signal back to Earth to confirm the spacecraft's arrival? If so, how about sending a picture and some measurements back to Earth? --Bowlhover 06:15, 3 September 2006 (UTC)

If thousands of years have passed, the nuclear fuel may have lost much of it's radioactivity by then, unless you choose a fuel with a very long half life, in which case only a very low power output would be produced. StuRat 07:13, 3 September 2006 (UTC)

We have to wait ten years to get news back from Pluto. Does it really seem plausible that we could set up communication with another star on a reasonable timespan? The Alpha Centauri article says it'd take 4.39 years just for the return message to flash back to us, at the speed of light. Black Carrot 06:23, 3 September 2006 (UTC)

Other than that, though, and the near insurmountable difficulty of calculating and following the right trajectory, and the additional difficulty of sending a tight enough signal in just the right direction to hit the Earth half a decade later, I don't see why not. Black Carrot 06:29, 3 September 2006 (UTC)

I know that sending a probe to Alpha Centauri will take a very long time, but even if it takes 18000 years, that's OK. The reason I asked the question was because I'm curious about whether any electronic equipment can survive in empty space for tens of thousands of years, and still be operational.

As a separate question, what's currently the most realistic way to travel to Alpha Centauri? Again I don't care about the time it takes, just that it's realistic. --Bowlhover 06:49, 3 September 2006 (UTC)

After edit coflict:

Possible? Maybe. Pointless? Certainly. A few decades from now we will be able to build a spaceship that will overtake the one we send now before it reaches the star. This will remain true until the time it takes a spacecraft to get to a given star will approach the time it takes to develop a considerably faster spacecraft. By that time we might also live longer than that time, so people then might be interrested in doing this. But by that time we may also have other means to get that info without travelling there, so we may never travel to the stars. DirkvdM 06:59, 3 September 2006 (UTC)

Any traditionally rocket propelled ship would surely be picked up a century later by our then much faster ships, and put into a museum. This takes all the fun out of spending billions of dollars to send the first ship, doesn't it ? StuRat 07:05, 3 September 2006 (UTC)

Product Success

If I wanted to find out how successful something's been (how many copies a book's sold, say) how could I get that information reliably? Black Carrot 06:33, 3 September 2006 (UTC)

rubella virus

what system in the body does the rubella virus (aka german measels) occur in? Sammie hero 07:14, 3 September 2006 (UTC)