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April 9

*Urgent Question*

Will someone please explain to me why bands occur in nanocrystals containing only a few hundred to a few thousand atoms? The article says the number of atoms must be on the order of $10^{20}$ so why does this occur with so few? Zrs 12 (talk) 00:49, 9 April 2008 (UTC)

Which article? and what type of bands are you talking about? Infrared?--Shniken1 (talk) 01:10, 9 April 2008 (UTC)

Sorry. In the article entitled electronic band structure and I'm talking about bands like contain electrons (kind of like electron orbitals). Zrs 12 (talk) 01:15, 9 April 2008 (UTC)

That article suggests that 'bands' are simply a term used to describe the electronic energy levels of a solid when lots of atomic orbitals (with similar but slightly different energy levels) come together. One atom will still have a conduction 'band' but rather than a band of different energy levels it will be one discrete electronic transistion (an electron jumping from ground to excited state). When lots of the discrete energy levels come together they produce bands of slightly different energies. Hope that makes sense.--Shniken1 (talk) 04:13, 9 April 2008 (UTC)

I know, but why are there bands (continuums of electron orbitals) when there is such a small congregation of atoms? Zrs 12 (talk) 18:53, 9 April 2008 (UTC)

The article appears very clear about this: sharing of electrons between multiple atoms "produces a number of [...] orbitals proportional to the number of atoms. When a large number of atoms (of order 10²⁰ or more) are brought together to form a solid, the number of orbitals becomes exceedingly large, and the difference in energy between them becomes very small, so the levels may be considered to form continuous bands of energy." Thus a "band" is never a true continuum, it is always a collection of individual levels, with the number of levels similar to the number of atoms. If there are "many" atoms, and thus "many" levels, it will be convenient to ignore the discrete nature, and think of the band as a continuum, but there is no general definition of what constitutes "many" in this sense. Only in the context of a particular experiment will there exist a definition of "many", given by how small an energy difference between successive levels can be and still affect the outcome of that experiment. The number 10²⁰ in the article is meant as an indication of the vast number of atoms in a "typical chunk of solid", not as a definition of "many". If the number of atoms is small enough that it makes sense to think of the individual energy levels within it, as may be the case in some nanocrystals, people may still choose to refer to this collection of levels as a "band". --mglg_(talk) 17:40, 10 April 2008 (UTC)

Well, I thought it was something about breaking the lattice symmetry of the crystal or something. Can anyone maybe expand on this (if it is in fact correct)? Zrs 12 (talk) 03:25, 11 April 2008 (UTC)

Current electricity

In current electricity questions, we frequently come across questions in which it is given that say a positive charge is moving from left to right or a positive charge is moved in an electric field, etc.. i want to know that how can a positive charge be moved?? because positive charge is present on protons and the protons are bounded inside the nucleus so how can we move the protons inside a conductor or elsewhere when they have been bounded by the nucleus. also as i have been taught that current is caused by flow of free electrons, do we have free protons of this type too, which can be moved?? —Preceding unsigned comment added by GK ROCKS (talk • contribs) 03:55, 9 April 2008 (UTC)

The direction of an electrical current is defined as the direction a positive charge would flow. This was defined before the electron and proton were discovered and now that we know that it is the negative electon that carries the current it has become quite confusing. It is however possible to move a positive charge, if you put electrodes in a salt solution the cations (+) will move to the negative electrode. There are also carbon nanotube wires that may be able to carry protons as a current, or in particle accelerators.--Shniken1 (talk) 04:20, 9 April 2008 (UTC)

The nucleus as a whole has a positive charge, so if you move a bare nucleus a charge will flow too. Graeme Bartlett (talk) 04:31, 9 April 2008 (UTC)

If you knock an electron off an atom, say in a semiconductor, it will leave behind a positive charge, sometimes described metaphorically as an electron "hole". If a nearby electron then "fills" that hole (takes the place of the first electron), then it will leave behind a positive charge. So no, the positive charge itself doesn't move, but the result is the same as if it did. It's like a sliding puzzle, where it is the plastic numbers you slide around, but from a distance it looks as though the hole is moving around. Also, in an acid battery, both positive and negative ions are traveling in opposite directions. The details of whether electrons are traveling in metal or ions are moving through a solution are not relevant to describing the circuit. kwami (talk) 07:26, 9 April 2008 (UTC)

You might find the article on ion very helpful. In most cases around the home, current is the flow of electrons through a metal conductor (wire). The reason these charges move is because they are subject to a force due to an electric field - this the easiest way to cause a charge to move. In many chemical batteries, current also includes ions in solution undergoing an electrochemical reaction. In some more obscure cases, such as Earth's Van Allen belts, current can be a complicated interaction of ions, electrons, and time-varying electromagnetic fields. In this case, yes, we have free protons caused by ionized hydrogen; there are many other types of positive ions. Nimur (talk) 15:06, 9 April 2008 (UTC)

Note that in Electrophoresis (and other situations where you have current passing through a salt solution) in addition to the negative ions moving one way, you'll have positive ions moving the other way as well. In a solution of common salt, for example, it is not free electrons which travel to make the current, but the Cl^- and Na⁺ ions which move back and forth. -- 128.104.112.85 (talk) 17:23, 9 April 2008 (UTC)

For an analogy, consider warm and cold air. If you leave the wooden front door of your house open, but the glass storm door is still closed, the house will cool down more quickly. Some people might call this "letting the cold in", although technically it's "letting the heat out", since heat is the vibration of atoms and cold is the lack of this vibration. However, you can think about it either way, it doesn't really matter on a practical level. Similarly, you can think of protons flowing from one location to another, even though they really don't do that, if you like. One exception would be ionized normal hydrogen, where you do indeed have flowing electrons and protons. StuRat (talk) 15:46, 9 April 2008 (UTC)

StuRat, I have a long-standing complaint against the anecdote of "letting the cold in/letting the heat out." The flaw in the analogy is that it fails to consider convection, or bulk motion of air mass. In the purely thermodynamic sense, it is true that heat always flows from hot to cold reservoirs; but in the unique case of fluid motion, cold air can move due to a pressure gradient, viscous dragging, and a wide range of complicated interactions. So, in fact, opening a door is neither letting heat in or out; it is letting air in or out; and that air carries a certain amount of heat with it convectively. Nimur (talk) 16:04, 9 April 2008 (UTC)

That would be why I included the glass storm door in the example, to prevent any air from entering or leaving the house. Thus, only heat transfer occurs. StuRat (talk) 17:03, 9 April 2008 (UTC)

If you rub a glass rod with a piece of silk the glass will acquire a positive charge. (while the silk acquires a negative charge). If you move the glass rod from left to right, you are moving a positive charge. What is complicated about this? Edison (talk) 18:03, 9 April 2008 (UTC)

The fact that a proton isn't flowing from one atom to the next maybe. But anyway as someone said it current was said to flow positive to negetive by convention. Once we discovered protons and electrons we realised they got it wrong. Electrons flow from negetive to positive in a circuit while the protons just sit there. Or a 'hole' (a proton with no matching electron) moves from one atom to the next flowing positive to negetive--155.144.40.31 (talk) 03:30, 10 April 2008 (UTC)

I have a real problem with the notion of protons jumping from atom to atom. That would constitute transmutation. Add a proton to an atom and it becomes a differnet element. Add or subtract an electron and it stays the same element. The change in binding energy would be large if protons jumped from atom to atom to effect a flow of current. That is not what hole current is. Edison (talk) 04:19, 10 April 2008 (UTC)

Indeed. In hole current, an electron moves into the empty space but leaves behind another empty space where the electron used to be. Kwami's sliding puzzle analogy is a good one. AlmostReadytoFly (talk) 08:18, 10 April 2008 (UTC)

And, of course, the electrons do not actually "flow" in any normal sense when a current flows through a wire, so we would be "wrong" whichever direction we agreed on by convention. 78.32.74.48 (talk) 15:35, 12 April 2008 (UTC)

Solid and Solid Shape

what is the differencebetween a solid and a solid shape —Preceding unsigned comment added by 72.27.45.24 (talk) 12:27, 9 April 2008 (UTC)

Typically, solid refers to a phase of matter while a solid shape refers to a more abstract mathematical concept. Do you have more context where these terms were used? Nimur (talk) 15:08, 9 April 2008 (UTC)

Nitrogen requirement of microorganisms

I know that some microorganisms can get their nitrogen requirements met with inorganic substances such as nitrate salts or urea. Others need organic nitrogen sources such as peptones or amino acids. I am looking for some rules of thumb along these lines, e.g. "most fungi can be cultured with nitrates" or "gram-positive bacteria usually require amino acids". Any little bit of information you can offer could help; maybe we can come up with a rule of thumb if none exists. ike9898 (talk) 14:57, 9 April 2008 (UTC)

There's some information in our article on nitrogen fixation; that doesn't fully answer your question, though. Nitrogen fixation refers to conversion of near-inert atmospheric nitrogen into bioavailable forms. I gather that you're looking for the broader set of organisms that can use any bioavailable inorganic nitrogen to generate all the amino acids de novo. Unfortunately, our article on amino acid synthesis doesn't list the organisms with these capabilities, though the navboxes at the bottom of that page cover all the important biochemical pathways involved. TenOfAllTrades(talk) 15:45, 9 April 2008 (UTC)

Orbit

If an object on a satellite is propelled radially toward the mass being orbited what will be its path? Will it orbit at a more eccentric orbit, or will it return to the same orbit as the satellite from which it was thrown? Cslloyd (talk) 15:17, 9 April 2008 (UTC)

To make sure I'm understanding the suggestion, we're talking about a guy on the space station throwing a baseball at the Earth (more or less), right? In that case, and neglecting out air resistance and such, the baseball will orbit with a slightly different eccentricity (though not necessarily more, depending on the orbit of the space station) while still crossing the orbit of the space station. Fully raising or lowering an orbit is generally accomplished by complementary thrusts at opposing points in the orbit, not with a single thrust. — Lomn 15:43, 9 April 2008 (UTC)

If the baseball is thrown with sufficient speed towards earth, it will enter an eccentric orbit with a collision to the planet's surface. This is almost intuitive; throwing a ball down does make it go down; the trick is that it is thrown from a moving "platform" and already has a (very significant) angular velocity / angular momentum. You can compute the trajectory if you know its initial orbit and the velocity it is thrown at. It is also worth noting that large transfer of momentum to the baseball will also result in equal and opposite reaction on the astronaut, to conserve momentum for the complete system. Nimur (talk) 15:52, 9 April 2008 (UTC)

(Addendum) As Lomn pointed out above, it is also possible that the baseball's new orbit does NOT collide with the planet (neglecting air resistance and only considering "hard impacts"). In that case, the new orbit will be more eccentric, as mentioned by Lomn, but will intersect the original point where it was thrown from. Nimur (talk) 16:00, 9 April 2008 (UTC)

Incidentally, this experiment has been conducted from the ISS. — Lomn 17:35, 9 April 2008 (UTC)

If an object were projected from a satellite in low earth orbit in a retrograde direction with about 1% of the satellite's orbital velocity, it would reenter the earth's atmosphere and burn up or land depending on its aerodynamics. A velocity of "throwing" of 170 mph or thereabouts should suffice. This would be at a right angle from the direction posited by the questioner. Edison (talk) 17:56, 9 April 2008 (UTC)

...but the golf ball that was hit from the ISS in Nov 2006 is still in orbit nearly 30 18 months later - see this tracker. Apparently NASA predicted it would stay in orbit for only 3 days ... Gandalf61 (talk) 19:58, 9 April 2008 (UTC)

It's those new graphite drivers, they've ruined space golf ;) Franamax (talk) 21:02, 9 April 2008 (UTC)

Nov 2006 was only 18 months ago, not 30. --ChokinBako (talk) 23:11, 9 April 2008 (UTC)

Gandalf is from the future and momentarily forgot this is the past aicmfp 130.88.140.121 (talk) 15:56, 10 April 2008 (UTC)

Hertz

Our article Hertz has a table conveniently telling us all the forms of "hertz" combined with all the SI prefixes. The familiar ones like kilohertz, megahertz, and gigahertz are there, but so are units smaller than the hertz, from the decihertz (0.1 Hz, i.e. once every 10 seconds) all the way down to the yoktohertz (10^–24 Hz, i.e. once approximately every 3 x 10¹⁷ years (about 23 million times longer than the age of the universe). My question is, are these units of frequency smaller than the hertz ever actually used in real-life applications? I don't just mean the really implausible ones like the yoktohertz, I mean even things like the millihertz (once every 16'20"), microhertz (once approximately every 11.5 days), and nanohertz (once approximately every 31.7 years). Is there anything in real life whose frequency is actually measured in those units? —Angr 16:53, 9 April 2008 (UTC)

A quick google search (ignoring the definition pages) yields the following scientific topics (primarily journal article titles):

• Millihertz Quasi-Periodic Oscillations from Marginally Stable Nuclear Burning on an Accreting Neutron Star
• Isolation transformer passes millihertz signals.
• Millihertz Oscillation Frequency Drift Predicts the Occurrence of Type I X-ray Bursts
• The Last Few Microhertz: Eliminating Remaining Discrepancies Between Observed and Calculated Solar Oscillation Frequencies
• Golf: Solar Signal for Frequencies Below 5 microHertz
• T violation and microhertz resolution in a ring laser
• Pulsar Timing Array -- A Nanohertz Gravitational Wave Telescope
• Probing the Nanohertz Gravitational Wave Background

It looks like the units are primarily used in astronomy, although the sample set may be biased. -- 128.104.112.85 (talk) 17:30, 9 April 2008 (UTC)

(ec) mHz, nHz. In astrophysics, orbital periods (if expressed as a frequency) will be in these ranges. -- Coneslayer (talk) 17:32, 9 April 2008 (UTC)

That makes sense, thanks! And to judge from one of the titles listed above, pulsars' radiation emissions can also be measured in Hz. That article says pulsars' periods range from 1.5 ms to 8.5 s, but presumably it could also be stated in terms of frequency ranging from 120 mHz to 670 Hz. Next question: in my original post I wrote that 1 nHz corresponds to a frequency of approximately 31.7 years; am I right in thinking that 12:00 midnight on New Year's Day also occurs at a frequency of approximately 31.7 nHz? Or have I screwed up my math somewhere (all too possible)? —Angr 18:06, 9 April 2008 (UTC)

I think it depends on the definition of year you use. It looks like most are around 3.2×10⁷ s though, and inverting this gives 3.1×10⁻⁸ Hz or 31 nHz. --Prestidigitator (talk) 18:25, 9 April 2008 (UTC)

The traditional approximation for astronomers is π × 10⁷
s. -- Coneslayer (talk) 19:02, 9 April 2008 (UTC)

What I was mostly interested in is knowing whether I got it right that when 1 nHz corresponds to a frequency of x years, then years occur at a frequency of x hertz. I wasn't expecting that apparent coincidence. —Angr 21:06, 9 April 2008 (UTC)

The examples you give all differ from the unit of hertz by only a SI prefix. I have most commonly seen scientific notation used to express smaller frequencies in plain hertz like (e.g. 2.3×10⁻³ Hz), but the metric prefixes are systematic and (many of them) common enough that it seems either (e.g. 2.3 mHz) should be clear to the reader, which is what is really important. You may also find that for applications where very low frequencies are common that the measurements used are instead that of periodicity or wavelength rather than frequency. I'm sure you could easily do Google searches for variations of herz ("millihertz", "milli hertz", "mHz", "centihertz", "centi hertz", "cHz", etc.) to see if you come up with anything. What is the purpose of the question? Is it idle curiosity, or are you trying to determine whether it would be proper to use a value in a particular context, or what? --Prestidigitator (talk) 18:04, 9 April 2008 (UTC)

It's mostly idle curiosity, perhaps with an eye to adding a discussion of these units at Hertz#Applications, which at the moment only discusses things measured in hertz and the units larger than the hertz (kHz, MHz, GHz, etc.). —Angr 18:12, 9 April 2008 (UTC)

Heavy water question

Because of the laws of thermodynamics, just having heavy water lying around in a non-sealed container will cause it to react with the light water vapour in the air, gradually causing a situation where I have plain old light water lying in the container and an extremely thin concentration of heavy water vapour in the air around me. Of course given little enough heavy water in the first place, this is perfectly safe, but it will lead to loss of valuable heavy water. So my question is, how quickly will this happen, and what can be done to slow it down? JIP | Talk 17:43, 9 April 2008 (UTC)

This is a very difficult question to answer quantitatively. This page goes into a bit of a discussion about half of the problem—how fast does liquid water move to the gas phase in an evaporative process? (At constant humidity, you have a dynamic equilibrium between evaporation and condensation, such that water is entering and leaving the liquid phase at constant, equal rates.) The rate of exchange of heavy water into the gas phase is going to depend greatly on the surface area of the container, the depth of the container, the amount of mixing and circulation of the liquid in the container and the air above it, the temperature, any agitation of the liquid-air interface, etc..

If you use a broad, shallow pan of warm heavy water and put it into a room with a fan blowing over the surface (or even better, with a bubbler circulating room air through the liquid in the pan) the equilibration between light and heavy water will occur many orders of magnitude more quickly than if you have the liquid in cool bottle with a narrow mouth sitting in still air. TenOfAllTrades(talk) 18:47, 9 April 2008 (UTC)

Just to complicate things still further, once you have a mixture of H₂O and D₂O in the liquid phase, you'll get some HDO (half-heavy water? :-) due to hydrogen ion exchange. That gives you three molecular species to keep track of. JohnAspinall (talk) 20:39, 9 April 2008 (UTC)

And why not add some acid to it so that you get HD2O+, H2DO+, D3O+(?),H3O+,H2O,D2O,HDO.....--Shniken1 (talk) 00:34, 10 April 2008 (UTC)

Is there a purpose to why you have your heavy water just sitting around?--155.144.40.31 (talk) 03:26, 10 April 2008 (UTC)

I don't actually have any heavy water yet. I'm trying to purchase some, in order to conduct experiments on heavy ice in normal water. As I have not done anything like this before, I want to make sure of the necessary precautions in advance. JIP | Talk 20:59, 10 April 2008 (UTC)

In most cases the controlling quantity is average air velocity. In a matter of seconds after being exposed to air, a microlayer of air saturated in heavy water vapor will form above the heavy water liquid. In most environments the rate at which this is transported away from the liquid surface is governed by the average air speed (only in very, very still air is diffusion more important than local turbulence). Because of things like leaky doors and air conditioning, empty indoor environments typically have ambient air speeds of 0.1 - 10 mm/s. To order of magnitude, you might expect to lose heavy water at a rate that is of order the area of your exposed surface times the ambient air velocity times the saturation vapor density. Which suggests a number like 10-70 mg lost per cm^2 of surface area exposed per hour in an empty room. If you are doing silly things like admiring your heavy water and breathing over it, one could easily increase this by one or more orders of magnitude. Obviously the best solution is to keep your heavy water in a sealed container whenever possible. Dragons flight (talk) 06:52, 10 April 2008 (UTC)

What histone modifications exist at <<DNA sequence>>?

Does anyone know a method by which one could ascertain the histone modifications that exist in a population of cells at a particular DNA sequence? I know the reverse is possible (finding out what sequences enjoy the comfort of particular histone modifications). ----Seans Potato Business 17:45, 9 April 2008 (UTC)

Anergy

An article I read from 1993 describes a process of anergy where the immune system's response to a specific antigen can be inhibited (at least temporarily) while the rest of the immune system is left unaffected. This exists naturally to prevent our bodies from destroying themselves, and seems to show promise in tissue grafting and the treatment of autoimmune diseases but our article on anergy is just a stub. I'm assuming that 15 years would allow enough research to substantiate some of its potentials. Is this something that the scientific community hasn't done much research on or have Wikipedians failed to document major studies on it since 1993? — Ƶ§œš¹ _{[aɪm ˈfɻɛ̃ⁿdˡi]} 19:27, 9 April 2008 (UTC)

Or perhaps it's just been unsuccessful? I don't know, just guessing. Imagine Reason (talk) 00:17, 16 April 2008 (UTC)

Disadvantage to bilingualism in evolutionary point of view

It's been shown that babies can distinguish all the phonemes available, and that as they get older they find it more difficult to distinguish phonemes that are not important in their native language. If exposed to two languages, they retain the ability to distinguish the phonemes important to both languages. I understand in a general sense that pruning brain connections is an important thing, but in this case there's no evidence that bilingual (or multilingual) children learn their first language any worse than monolingual kids, or have any other disadvantages. So why do we lose this ability? What are we gaining from that? moink (talk) 21:04, 9 April 2008 (UTC)

I don't think it would be wise to assume that we gain anything from losing the ability to distinguish foreign phonemes. It could simply be a side-effect of the way our brains learn language. (A spandrel (biology).) --Allen (talk) 21:28, 9 April 2008 (UTC)

In fact, according the article I just linked to, Noam Chomsky believes language may itself be a spandrel, which would render the entire question moot. --Allen (talk) 21:30, 9 April 2008 (UTC)

Not only that but higher life expectancey is a relatively mordern thing that may have never had a part to play evolutionarily because we were never able to age to beyond the point. You don't have to go back to far for life expectancy is the low 20's.--155.144.40.31 (talk) 03:23, 10 April 2008 (UTC)

My understanding is that the ability to learn language (not just phoneme distinction, but all aspects of grammar) is directly related to brain plasticity so that, once your brain becomes less plastic, your ability to acquire language diminishes. Diminished plasticity, I'm sure, has a number of evolutionary benefits. — Ƶ§œš¹ _{[aɪm ˈfɻɛ̃ⁿdˡi]} 04:14, 10 April 2008 (UTC)

My favorite (if possibly flawed) explanation for the (relative) loss of ability to learn language before puberty I read in Morgan's "Descent of Woman" -- otherwise mother's would learn babytalk instead of vice-versa. Saintrain (talk) 18:57, 14 April 2008 (UTC)

Phasor diagrams

In a series circuit composed of an a.c. supply, a resistor and a capacitor, how do you form the phasor diagram?Bastard Soap (talk) 21:09, 9 April 2008 (UTC)

The angle of the phasor is inverse tan of (Vl - Vc) / (Vr), (or inverse tan of (Xl - Xc)/ R). Obviously Vr (or R) is the magnitude in real direction and Vl-Vc (or Xl-Xc) is the magnitude in the perpendicular. So you just need to know the capacitor impedance and the resistance--155.144.40.31 (talk) 03:18, 10 April 2008 (UTC)

heat

affects of heat on rubber —Preceding unsigned comment added by 70.226.196.132 (talk) 22:01, 9 April 2008 (UTC)

Melting —Preceding unsigned comment added by 128.163.172.108 (talk) 22:13, 9 April 2008 (UTC)

And hardening. -- kainaw™ 22:54, 9 April 2008 (UTC)

or burning --S.dedalus (talk) 22:55, 9 April 2008 (UTC)

Heat transfer. This is fun! --Mdwyer (talk) 23:04, 9 April 2008 (UTC)

Tire wear. --Julia Rossi (talk) 00:36, 10 April 2008 (UTC)

Shrinkage. --Allen (talk) 02:09, 10 April 2008 (UTC)

Also the release of nasty fumes. --Allen (talk) 02:15, 10 April 2008 (UTC)

Vulcanization? — Kieff | Talk 02:49, 10 April 2008 (UTC)

Sterilization Graeme Bartlett (talk) 02:50, 10 April 2008 (UTC)

Perishing. Gwinva (talk) 03:00, 10 April 2008 (UTC)

Connect 4 Diagonal FTW!--Shniken1 (talk) 03:10, 10 April 2008 (UTC)

Degradation and Unplanned pregnancy. DMacks (talk) 04:46, 10 April 2008 (UTC)

Walter Matthau [1] ---Sluzzelin talk 11:44, 10 April 2008 (UTC)

The Persistence of Memory?--Shniken1 (talk) 13:23, 10 April 2008 (UTC)

Tire fire - Gandalf61 (talk) 15:05, 10 April 2008 (UTC)

Bouncing pucks. Franamax (talk) 15:41, 10 April 2008 (UTC)

C-c-c-combo breaker!! —Keenan Pepper 16:07, 10 April 2008 (UTC)

or a new stanza —Preceding unsigned comment added by 79.122.13.205 (talk) 16:46, 10 April 2008 (UTC)

...While we're off topic. Nimur (talk) 16:53, 10 April 2008 (UTC)

Here's a dual meaning: Entropy increases (applies to this thread too:) Franamax (talk) 18:54, 10 April 2008 (UTC)

Smells bad. Edison (talk) 19:06, 10 April 2008 (UTC)

So, chewie. Julia Rossi (talk) 00:05, 11 April 2008 (UTC)

alternative music Gwinva (talk) 03:58, 11 April 2008 (UTC)

Expansion Of The Universe

Scientists say that galaxies are moving away from each other, so the Universe is expanding. If the Universe was expanding, and we are integral parts of it, wouldn't that mean that we were expanding too? If so, wouldn't this mean that there would be no noticeable difference in distance over time? If this is the case, then galaxies must be moving away from each other for a different reason.--ChokinBako (talk) 22:57, 9 April 2008 (UTC)

We would be expanding, but there are forces holding us together - on the small scale, mostly electromagnetic force, and on the larger scale more often gravitational force. Imagine you and a friend are standing, along with lots of other people, on the surface of a giant balloon, and you're holding your friends hand. When the balloon gets inflated, everyone moves away from each other, but you and your friend stay together because you're still connected. Confusing Manifestation(Say hi!) 23:04, 9 April 2008 (UTC)

See Metric expansion of space. Imagine Reason (talk) 23:09, 9 April 2008 (UTC)

But the article does not explain why the "raisins" (in the last illustration) do not expand along with the balloon. Are the "raisins" the galaxies, held together by gravitation? It would still be possible for the metric of space-time to be expanding, or even to be contracting, without any measurement being able to detect this if our unit of measurement is also contracting at the same rate.

Is there any evidence to refute my (perverse) theory that the metric of the universe is actually contracting, but that the space between galaxies is contracting less quickly than our unit of measurement? Would this not also explain the red shift because the light emitted long ago was from a universe with a longer unit of measurement? 78.32.74.48 (talk) 16:12, 12 April 2008 (UTC)

As Confusing explained, there are forces holding nearby objects together. For example, our solar system will stay intact while we fly away from other galaxies. Whether we'll be torn apart eventually, I think, is still up in the air. Note that this would mean intelligent species, if they survive till that time, will have no way of determining that there's anything else in the Universe but their solar system.

As for your perverse theory, wouldn't the CMB lose its intensity much slower and even strengthen? Imagine Reason (talk) 15:13, 14 April 2008 (UTC)

April 10

Huge sandbanks!!!

Hi. When I went to a nearby plaza recently, I saw some huge sandbanks, the remnants of giant snowbanks that have melted and left their sand, dust, and other material in a huge heap. I mean, even with a huge snowbank, you would have thought that it would have eventually melted and left behind maybe a few deposits of dust, right? Well, no. It appears that due to this winter's amazing snowfall amounts, the snow contained extra amounts of sand, and created a heap. Now, I know that what usually happens is, snow from the streets gets shovelled onto the lawns, the snow contains dirt, as the snow melts, the dirt is left behind, the melting water forms mini-rivers flowing over silt, and as the water from the dirt evaporates, it turns into sand, and spring wind blows the sand across the street, forming mini-sandstorms, and the cycle repeats again. However, at this plaza, from which probably about 20,000 square metres of snow was shovelled into one place, a huge snowbank, and later a resulting heap developed. Well, this heap is huge, and I think it must weigh 1000 tonnes. It's still wet, but I think as the water evaporates this heap will remain. First of all, where does all the dirt come from? Yes, I know that as the snow is shovelled, it must contain massive amounts of sand from eroded ashphalt, tar from the cars and roads, remnants of road salt, dirt carried from grass by water to the roads, sand carried from elsewhere from dust blown from previously melted snowbanks, silt from nearby places, dirt carried by walking people, grains of metal from the machinery of the snowploughs, dust from industry, manufacturing, and heavy machinery, atmospheric dust, as well as dust, pollen, and pollutants carried down by snowflakes, but why such a massive amount? Also, why does a snowier year tend to bring larger heaps, is it because more snow requires more shovelling and picking up the dust from the roads, or because of more dust in the snowflakes deposited? Also, what will happen to the heap? Will it stay until next winter and keep building up, will it be manually shovelled away by heavy machinery, or will it be blown away by the wind and eroded by water? Either way, wouldn't that create massive sandstorms in the area as it dries up and is carried to nearby areas? If a sudden windstorm blows on the dust, would it bring sand to areas kilometres away? If it rains (heavy rains are in the forecast within the next few days), will the rain cause it to stick to itself, or erode it away? Or will some people just use it as a bike ramp? Will it affect local wind patterns? Thanks. ~AH1^(TCU) 00:46, 10 April 2008 (UTC)

Apologies for a banal answer to such a cosmic question, but are you sure it couldn't have been the remnants of the sand (sometimes mixed with salt) which is typically spread on snowy/icy roads to increase traction? The snowier the winter, the more of that they have to spread, and it all ends up somewhere. —Steve Summit (talk) 02:40, 10 April 2008 (UTC)

As to what will happen, I suggest phoning the organization that arranged for the snow to be piled up there and asking them. That would either be the plaza management if the snow was all from the parking lot itself, or else your local city hall (or county government or whatever) if they arranged for snow from elsewhere to be dumped in the parking lot. --Anonymous, 03:26 UTC, April 10, 2008.

decision sequences

Is there a publication which shows decision/results sequences in which subjects had a choice of doing one thing or another, for instance to stay inside and stay warm or go outside without adequate clothing and become cold, with each decision sequence ending in a result, for instance the number of persons that developed a cold as the result of following one sequence of another? 71.100.160.37 (talk) 02:33, 10 April 2008 (UTC)

Lots of publications (both fiction and non-fiction) feature decision/results sequences. Can you be more specific? Also, from our common cold article: "Although common colds are seasonal, with more occurring during winter, experiments so far have failed to produce evidence that short-term exposure to cold weather or direct chilling increases susceptibility to infection, implying that the seasonal variation is instead due to a change in behaviors such as increased time spent indoors at close proximity to others."--Shantavira|^{feed me} 09:03, 10 April 2008 (UTC)

Colds are a good example but I am really looking for longer sequences with many more decision points such as someone ending up as a CEO versus a security guard position. BTW - One of the motives for having a statistically based sequence is that I completely disagree with the conclusion set forth above, which is based on experiments and not everyones actual experience. 71.100.160.37 (talk) 21:45, 10 April 2008 (UTC)

Echidna name?

Why are echidnas named after the monster of the same name? Is it because Echidna was half human/half snake and monotremes seem part mammal, part reptile? Vultur (talk) 03:08, 10 April 2008 (UTC)

They both have the same etymology (echidnas are not named after the mythological monster). Echidna the mammal comes from Latin echinus, from Greek εχίνος (ekhinos, meaning hedgehog), from εχίς (ekhis, meaning snake). As you can see in Echidna (mythology), they both come from the root εχίς. 70.162.25.53 (talk) 03:35, 10 April 2008 (UTC)

To confuse things a bit, the animal kingdom also has a genus named Echidna which fits the mythological description glancing eyes and huge snake, great and awful, with speckled skin, eating raw flesh beneath the secret parts of the holy earth (Don't know about the "fair cheeks"). According to the article on Homonym (biology) the name was first proposed for the aquatic genus and thus the eel has priority. The spiny genus was renamed Tachyglossus. ---Sluzzelin talk 11:30, 10 April 2008 (UTC)

murdoch

what's wrong with this guy's face excuse my bluntness. I'm not asking for medical advice on his behalf yada yada —Preceding unsigned comment added by 79.122.13.205 (talk) 13:04, 10 April 2008 (UTC)

When one gets older, the skin looses elasticity. Also, it looks like he's pushing his chin back into his throat, which causes your neck to look flattened. -- MacAddct  1984 ^{(talk &#149; contribs)} 14:16, 10 April 2008 (UTC)

"When one gets older, the skin looses elasticity" sounds like half of a skin-care ad! Can you tell me what the other half would be, in an NPOV way? (ie what is the solution? I've always wondered what the science is behind it once you remove the marketing). Thank you! —Preceding unsigned comment added by 217.116.40.195 (talk) 15:49, 10 April 2008 (UTC)

Haha, well I don't think there is any 'solution' for it, it's just a fact of life; however, I'm sure many skin product companies assure their customers that their products will guarantee them wrinkle free skin. Maybe botox injections? -- MacAddct  1984 ^{(talk &#149; contribs)} 16:01, 10 April 2008 (UTC)

Agreed, unless it's radical intervention, the rest is likely B$. Instead of my first guess which was sun damage], I'd say it's at least because he is 77, long days and nights and an unkind photographer. ; ) Julia Rossi (talk) 00:13, 11 April 2008 (UTC)

Nah, Murdoch's just half Shar Pei. :-) StuRat (talk) 14:28, 11 April 2008 (UTC)

why can't humans focus on two objects simultaneously like the chameleon? please also include the answer to my email - *redacted* thank you.

why can't humans focus on two objects simultaneously like the chameleon? —Preceding unsigned comment added by 203.193.135.51 (talk) 15:44, 10 April 2008 (UTC)

Take a look at Binocular_vision#Field_of_view_and_eye_movements. It seems chameleons are actually a very rare example. Human vision works by binocular vision, which requires both eyes to be looking at the same object to allow for depth perception. -- MacAddct  1984 ^{(talk &#149; contribs)} 16:32, 10 April 2008 (UTC)

Daniel Dennett has speculated that human consciousness may be a virtualization of a parallel processing machine as a serial processing unit (computing is moving in the opposite direction). The stream of consciousness that results would be hampered if our vision were divided into two exclusive fields. Imagine Reason (talk) 18:37, 10 April 2008 (UTC)

I can; can't everyone? Edison (talk) 19:04, 10 April 2008 (UTC)

Apparently they've done the exact experiment on people with brain injuries whose two sides of the brain can't communicate. They are shown different pictures for each eye, and they end up making up stories that reconcile the differences without any conscious effort. Imagine Reason (talk) 19:33, 10 April 2008 (UTC)

Thanks to maybe misreading Edison, there's Strabismus, and I've got this pic stuck in my head for the day.[2]. Or did you mean you can walk and chew gum at the same time? Julia Rossi (talk) 00:32, 11 April 2008 (UTC)

Anyone who experiments with stereoscopic photography is likely to develop the ability to voluntarily adjust the convergence of the two eyes, as when combining two photos into a stereoscopic view. This amounts to voluntarily causing the eyes to be crosseyed or wall-eyed. Others can trick the eyes by selecting a distant object and a nearby finger: look at the distant object and you see the finger double. Look at the finger and you see the distant object double.See Ben Turpin for an example of a performer who could roll his eyes around independently. Microscopists may learn to look with one eye through the lens and with the other at apiece of paper where they are sketching what they see. A photographer/videographer may become able to look with one eye through the camera eyepiece and with the other simultaneously at the larger scene. In selective attention experiments, people have been shown able to divide the attentional field even within the view from one eye to more than one area in the visual field. Edison (talk) 14:40, 11 April 2008 (UTC)

semiconductor resistivity

What is FOUR POINT PROBE METHOD in the measurement of semiconductor resistivity? —Preceding unsigned comment added by Shraktu (talk • contribs) 17:08, 10 April 2008 (UTC) Shraktu (talk) 17:13, 10 April 2008 (UTC)

Main article: Four-terminal sensing

-- MacAddct  1984 ^{(talk &#149; contribs)} 18:04, 10 April 2008 (UTC)

WHAAOE! —Steve Summit (talk) 00:59, 11 April 2008 (UTC)

Specifically, semiconductor test labs have a microscope-aided four-point probe for this task. This website from UC Berkeley provides theory and photos. Per WHAAOE, we should have an article with photos of this tool but I can't find any... here's an external site with photo-micrographs for a specific nano-wire application. Nimur (talk) 15:49, 11 April 2008 (UTC)

Computer Simulations of Black Holes

I've watched a few computer simulations of black holes and can't help but wonder if they're slightly misleading

As far as I know a black hole is supposed to have a gravitational pull so strong that not even light can escape so in theory if you were to actually be in the vicintiy of one you would never know it existed because all the light that is usually reflected off surfaces in order for you to see them would actually be 'sucked' into the black hole.

This makes me think that the only way you could actually tell visually that a black hole was 'nearby' would be that there would be an unusual absence of light in a particular direction.

I guess my question is are these simulations purely to allow people to learn about the path of anything approaching a black hole or is there some scientific truth to the multitude of colours displayed in these simulations? —Preceding unsigned comment added by 82.44.178.36 (talk) 20:39, 10 April 2008 (UTC)

Can't comment on the simulations you have been watching unless you give a link, but black holes are not exactly black. See our article on Hawking radiation for the reason. SpinningSpark 21:42, 10 April 2008 (UTC)

If I recall correctly, a black hole heats up nearby gases until they emit X-rays along the 'poles' of the singularity. Plus, if you see a space in the night sky where there's no light, that suggests the presence of a black hole. Correct me if I'm wrong, anyone, it's been a while since I took much interest in astronomy. Vranak (talk) 22:56, 10 April 2008 (UTC)

Black hole#Techniques for finding black holes seems pretty relevant. Someguy1221 (talk) 23:03, 10 April 2008 (UTC)

It's not that the black hole heats up gases; it's that if there is lots of matter around it will start to rub against other matter as it is pulled down into the black hole. Outside of the event horizon, what you see is the result of this friction. It's a lot of energy. See quasar. I think it's pretty neat—that something as apparently simple as friction is probably responsible for the most powerful energy sources in the universe. --Captain Ref Desk (talk) 23:20, 10 April 2008 (UTC)

Yes, that's a better description of what's happening than I gave; but the fact remains that if the black hole weren't there, the gases wouldn't be heating up. Ergo, the black hole heats up the gases. Indirectly (gravitationally). :) Vranak (talk) 15:50, 11 April 2008 (UTC)

I thought that the black spots in the night sky were caused by intergalactic dust.[won't put faith in a reading passage on an exam again.] I doubt black holes suck up all the light. Imagine Reason (talk) 23:45, 10 April 2008 (UTC)

(e/c) Outside the event horizon, the gravitational field around a black hole is just like that of any other large body of mass, like a planet or a star. Gravitational fields bend the path of light, so if there is a star on the other side of the hole to you, you will see a gravitational lensing effect. Confusing Manifestation(Say hi!) 23:04, 10 April 2008 (UTC)

it is only mass that is beyond the event horizon that is 'invisible' because the light it gives off gets sucked in. However before the event horizon matter can orbit the black hole just like a satellite orbitting a planet. And due to the strength of the block hole it would not be surprising to find large amounts of matter orbitting. I would guess the colours are meant to just be clouds of gas that are slowly orbiting and eventually going to fall through the event horizon.--Dacium (talk) 23:07, 10 April 2008 (UTC)

Clock of observer at center of the earth

Please follow my reasoning for a moment: Suppose that there was a hollow cave at the center of the earth that allowed an observer A to "float" freely. The observer would, then, not experience any acceleration due to gravity, since an equal force would act on him from all directions (shell theorem).

However, here's the question. Suppose there was another observer B positioned a considerable distance away from the earth. Relative to observer B, would he perceive A's clock to run slower than his? My intuition tells me A's clock would run slower, since even though A does not feel any force acting on him, he's still surrounded by nearby regions of intense gravity. Is my interpretation correct? Dmitry Brant (talk) 20:42, 10 April 2008 (UTC)

I don't see why. A's clock, unlike another that's floating in space orbiting Earth, isn't accelerating. If you consider the equivalence principle, there's no experiment, so long as A stays within the shell, for him or her to determine if the location is within the shell or very far away from Earth. Imagine Reason (talk) 20:58, 10 April 2008 (UTC)

The answer is yes due to gravitational time dilation. The path that you have to follow from A to B is important in this calculation. It goes through a gravitational field. Graeme Bartlett (talk) 21:27, 10 April 2008 (UTC)

Hmm. That's what I was thinking. Although the local field might have zero strength, the gravitational potential is definitely lower at A. It seems pretty obvious that a photon emitted from A will have lost energy and thus been redshifted if it reaches B. --Prestidigitator (talk) 22:28, 10 April 2008 (UTC)

Gravitational time dilation reaches its maximum at the surface of the planet (were gravity is the strongest) and falls away to zero at the center. At the centre of the earth there is no gravitational potential and time runs normally. For the guy way out in space there will be a very small gravitational potential, so his clock will run slower. If you assume he is so far away that the gravitational potential is also effectively zero, both clocks are the same and there is no dilation.--Dacium (talk) 23:00, 10 April 2008 (UTC)

You're speaking in terms of gravitational force, not gravitational potential. Gravitational potential strictly increases as one moves out from the center of the Earth. Someguy1221 (talk) 23:06, 10 April 2008 (UTC)

What would be handy here is a solution of the Einstein equations for a spherically symmetrical body. The Schwarzschild solution is only valid outside such a body. This paper describes the Tolman VII solution with a density profile of ${\frac {3}{8\pi }}\cdot ({\frac {1}{K^{2}}}-{\frac {r^{2}}{\beta ^{2}K^{2}}})$ for some constants K and β. Substituting β with 1 or values slightly above 1 into the (moderately complex) equations in the paper clearly shows that a stationary clock is running slower at the center than at the surface. Is there something like a general theorem for General Relativity saying that for any spherically symmetrical mass distribution clocks are never running faster at lower values of the radial coordinate? Icek (talk) 01:12, 12 April 2008 (UTC)

How does this collet work?

Hi all,

I just got a second-hand Black & Decker rotary tool, like a Dremel, which is supposed to have a "universal collet system". I'm pretty sure it has all the parts. However, I'm confused about how the collet works. On the assumption that it's the small metal sleeve with a wide head, then it looks almost exactly like the one at the bottom of the image here. However, it does not have any slits in it. It's a tube and the sides are completely solid. How is it supposed to tighten with no slits in it? I've tried putting in the "nut" part of the tool and tightening the nut, and I can still easily slip the bits that came with the tool.

Am I missing something? What is the point of a collet without slits in it?

Thanks! — Sam 23:52, 10 April 2008 (UTC)

You need to knock it right up hard! See Machine_taper —Preceding unsigned comment added by 79.76.215.59 (talk) 00:31, 11 April 2008 (UTC)

I don't think so. This is a small hand-held tool the OP is talking about. Here's an alternate suggestion. On my Dremel, I can completely remove the collet-tightening nut to change collets. The collets come in a couple of different (inside) diameters. Can you remove this purported collet completely? Perhaps it's in backwards? I don't know about a "universal collet system", but I am skeptical of a collet that claimed to be able to hold more than a small range of diameters. Do you have any way to measure (calipers?) the inside diameter of the collet and the outside diameter of your toolbit? JohnAspinall (talk) 14:36, 11 April 2008 (UTC)

Yes, it's removable, and I think "universal" was referring to the whole system, not that individual collet. What I can't understand, however, is how a collet without slits in it is supposed to work, especially given that it's the one they shipped with (assuming it's the original). There';s no way I can tighten the nut hard enough to actually maker a change in the diameter of the thing. — Sam 16:45, 11 April 2008 (UTC) —Preceding unsigned comment added by 63.138.152.238 (talk)

It looks to me like a keyless chuck, (I think they're also called universal chucks). It's a bit difficult to guess how all the parts in your photo go together but i'm guessing 'universal' as with keyless chucks means you screw the parts together and all the parts are interchangable. Looking at your picture, have you tried inserting the bottom left bit (on your pic) into the bottom right bit, then screwing it onto the main dremel unit? If that does work it's just a case of using the bits on your middle right and top left screwed on top of that to fit the appropriate accessories. Probably! Hope that works. Cosmic joker (talk) 00:26, 12 April 2008 (UTC)

April 11

Why are pollen count ratings so low?

Every spring across the southeast, we get pollen counts in the thousands easy: Atlanta Pollen Counts. You can't even tell that it's pollen season when there's less than a 200 pollen count. So why is 120 considered extremely high? Is that really the norm for most of the country? It seems like any place with flowering trees would easily break a hundred. What's the reasoning behind the system? 160.10.98.34 (talk) 00:00, 11 April 2008 (UTC)

People who are allergic to pollen can likely detect it at a much smaller count than others. StuRat (talk) 14:09, 11 April 2008 (UTC)

Chainmail vs Tasers

If someone wearing chainmail was tasered, what would happen? Would the current flow via the chainmail between the two electrodes, or would you just earth it? -mattbuck (Talk) 00:26, 11 April 2008 (UTC)

The current would take the easiest route, through the chainmail, and not much would pepetrate the person. Chainmail is heavy to wear however! Go for glomesh. But you may get sprayed with capsicum spray of you misbehave! Graeme Bartlett (talk) 07:13, 11 April 2008 (UTC)

I'm not sure this would actually help - due to skin effect, the power / signal will likely remain on the surface of the chain mail, just as it would likely remain on the surface of the human skin without chain mail. Even a surface current can cause incapacitating pain. Also, many taser systems actually penetrate the skin with a dart, so if the dart electrode were to make it through the holes in the chain mail, it would not pass any electricity through the armor at all. Nimur (talk) 16:00, 11 April 2008 (UTC)

If the bare metal part of the dart touched the chain mail while extending into the flesh, the chain mail should present a far lower electrical resistance than the flesh, resulting in a far smaller current through the victim than without the chainmail. The resistance of steel mesh should be a fraction of an ohm and the internal resisitance of the victim should be hundreds of ohms. Edison (talk) 22:48, 11 April 2008 (UTC)

Newton and the darkness of the night sky

I was reading a book last summer about the general history of cosmology, and it mentioned a situation where Newton had theorised that the heavens were held together by gravity, and some priest or bishop replied to the effect that if that was true there would be constant light at night when we look at the sky. I think I've got the details wrong, as I don't remember much of the book, but why is it that the sky is black rather than white? I know someone answered this question a century or two ago but I can't remember for the life of me. Thanks a lot. 81.96.161.104 (talk) 01:44, 11 April 2008 (UTC)

Olbers' paradox may answer part of the question. --Arcadian (talk) 02:20, 11 April 2008 (UTC)

Remember that light always travels in (not necessarily straight) lines, and for you to see light, the terminus of that line has to end in your eye. So the universe is indeed chock-full of radiation from stars. However, you can't see all this radiation unless all the rays suddenly turned a corner and decided to head directly for your eye. — Sam 16:50, 11 April 2008 (UTC)

Hi. Well, remember that stars' light travel in all directions, they're not like a flashlight where the light goes only in one direction. It's kind of like the infinite forest paradox: in an infinite forest, it would be impossible to see past it, in a finite forest, you can still see gaps. The entire observable universe is only about 15 billion light-years in radius, and we can't see past that. Also, nearly all the naked-eye stars not within the glow of the milky way are within about 10,000 light-years. Space is locally not totally uniform here. The milky way, as well as nebulae, the magellanic clouds, globular clusters, open clusters, supernova remnants, etc, all contain stars and are in our own galaxy, but most are either not naked-eye or only visible from a dark location. There are also the galaxies outside of our own, but only a few are naked-eye. The rest of the googols of stars are not visible at all because they're so far away, and their galaxies are not naked-eye. Some of the background stars may contribute to the skyglow observable even in the darkest-sky places in the world, along with the atmopshere, solar system debris, etc. Hope this helps. Thanks. ~AH1^(TCU) 23:25, 11 April 2008 (UTC)

Water on Mars

I've read that liquid water likely once existed in great quantities on the surface of Mars, but it always says "in the past" without specifying how long ago it was. My question is, when did all the water that supposedly made shorelines and carved canyons go away? -RunningOnBrains 03:04, 11 April 2008 (UTC)

It is thought that some geologic features remain, but the data haven't born that out yet. See Mars#Hydrology. Imagine Reason (talk) 03:14, 11 April 2008 (UTC)

The research reported in this BBC News story concludes that there haven't been large areas of free-standing water for four billion years. Since then, there may have been local short-lived "floods" as a result of the release of underground water by volcanic activity or meteorite strikes. There is some evidence from phtogoraphic surveys that small-scale local release of liquid water is an occasional ongoing process, but this is not confirmed. Gandalf61 (talk) 09:08, 11 April 2008 (UTC)

Hi. Well, if I remember correctly, NASA discovered water on Mars in the form of rivers, I think in 2004 or 2005 or sometime around there, oh and if you look at Google Mars, you will see features that are most likely created by rivers. I think this might be an image of water on Mars, and no, not the prank image of a glass of water on a Mars bar, although I don't think this image has been used in an article. Hope this helps. Thanks. ~AH1^(TCU) 23:30, 11 April 2008 (UTC)

Water on Mars?

I'm pretty sure that those findings, which in any case were not conclusive, have been reversed. I can be wrong, of course. Imagine Reason (talk) 02:21, 12 April 2008 (UTC)

Electric Vehicles, Cost

Disregaurding the battery X factor of electric vehicles, what would an electric vehicle comparable to say a 20,000 US dollar car cost if it could be mass manufactured? Are there any big differences in mass production that should make a mass produced electric vehicle more expensive than a mass produced regular one? Some people say that the electric motor is simpler than a combustion engine and thus would be cheaper. On the other hand, I can't find any real data to argue either way. When I say electric vehicle, I am refering to an all electric vehicle - not a hybrid. 129.2.152.144 (talk) 03:04, 11 April 2008 (UTC)Sam

Disregarding the cost of the batteries, I'd expect the electric car to be cheaper. But you can't, of course, ignore the battteries, since they are a major component of any electric car. Once you include them, the electric car becomes more expensive. Now mass production is a tricky issue, in that presumably there will be improvements in technology which will bring down the cost of electric vehicles if mass produced, but we can't predict how much that will bring the cost down. StuRat (talk) 16:54, 11 April 2008 (UTC)

Yes, an electric motor is usually cheaper than an equivalent ICE because a) it has a higher power to weight and power to size ratio and thus requires a smaller amount of raw material to build b) it is mechanically less complex - an electric motor typically has only one moving part, while an ICE may have hundreds of moving parts c) it is easier to assemble and d) it needs no active cooling, exhaust system, and catalytic converter. Pontentially, electric cars can also do away with the transmission, clutch, axle and differential, since electric motors are small enough to be placed inside each wheel. This simplicity could pontentially make electric cars much cheaper to manufacture than ICE cars.

Batteries will probably be the most expensive component of electric cars for the near future. The problem is that current batteries are not only expensive, but need to be replaced every 3-6 years. Battery depreciation is the biggest cost of owning an electric car; it is higher than the cost of purchasing the car itself. Will batteries become an order of magnitude cheaper as they are mass produced? Probably, if you take Li-ion batteries for mobile phones and laptops as a precedent. However, scalability is still an unknown issue. If the whole world decides to buy electric cars, the price of commodities needed for batteries (lithium) and electric motors (copper) may skyrocket, and that will put a lower bound on the price of an electric car. Cambrasa 19:22, 11 April 2008 (UTC)

How does a circuit "know" when it is closed?

Say there's a simple circuit which has a battery and a switch. When the switch is open, there's no current. When it's closed, current runs through the circuit provided by the battery. So how does the circuit "know" to have the current run once the switch is closed?199.76.153.227 (talk) 03:35, 11 April 2008 (UTC)

I'm sure there is an article (if not more than one) on electronic current. The old-school explanation, which I'm sure it out of style now, is to look at the negative side of the open circuit as a bunch of electrons. The positive side of the open circuit is a bunch of holes (waiting for electrons to fill them). When you close the circuit, an electron is suddenly next to a hole. So, it hops over on that hole. It finds another hole, so it hops over to that one - on and on. As it moves, it leaves a hole behind it. The next electron sees that hole and hops over. You can then view it as either electrons flowing from negative to positive or holes flowing from positive to negative. -- kainaw™ 03:39, 11 April 2008 (UTC)

When the circuit closes, the negative and positive side have different voltages. Just like when a U-shaped pipe fill with water but the water level on one side is higher than the other. So, the energy started to go from one side to another. Where the media is electrons. Visit me at Ftbhrygvn (Talk|Contribs|Log|Userboxes) 05:17, 11 April 2008 (UTC)

When you close the switch, an electromagnetic wave travels at the speed of light in both directions from the switch back to the battery. As the wave sweeps over the surface of the conductor current starts to flow. Graeme Bartlett (talk) 07:06, 11 April 2008 (UTC)

Really? Can you provide a source for that? AlmostReadytoFly (talk) 08:08, 11 April 2008 (UTC)

Charge carriers in a conductor are not stationary in the absence of an electric field but move around, essentially at random. The battery generates an electric field which superimposes a drift velocity on the electrons in the direction of the field. Before the switch is closed, charges will therefore build up at its terminals. This charge will itself be generating a field in the conductor which opposes the battery field. Charge will continue to build up until the two fields are equal and opposite at which point no more net current is flowing. At this point virtually all the field is between the switch contacts as the field along the conductor is cancelled. This effect amounts to capacitance. At the moment the switch is closed, the charges built up at the contacts will start drifting across the switch.

Since the transient originated at the switch it is obviously going to propagate from there. Not at the speed of light however, in most cables the speed is around 2/3 C (function of insulator material mostly). Sorry, I could not readily find you a source other than my (obviously uncitable) undergraduate notes.

It might also be of interest that there is a similar charge build up at bends in the conductor which generate a field which drives the charges "around the corner". SpinningSpark 08:54, 11 April 2008 (UTC)

I will have a look to see if some one has this on the web. I will give a bit more of a physical point of view. Before the switch is closed there is the voltage of the battery across the contact. When the switch closes the current flows. Initially information does not travel faster then the speed of light, so right at the start the battery has no current flowing, but there is current flowing through the switch. The wire can be modeled as a string of inductors, alternated to capacitors between the leads going to the switch, a transmission line. If the wire is in vacuum, the wave of EM field on the surface travells at the spped of light, but if it is insulated the situation is more complex and slower! Graeme Bartlett (talk) 09:01, 11 April 2008 (UTC)

There is a wikipedia article on the maths involved: Telegrapher's equations developed by Oliver Heaviside. People using telegraphs used switches to turn on and off a long line with current running in it and the extreme lengths meant that this had to be understood. Graeme Bartlett (talk) 09:13, 11 April 2008 (UTC)

For corroboration, there's a page on All About Circuits that explains the wavefront model for the closure of a switch. It's a standard part of transmission line theory. --Heron (talk) 20:41, 11 April 2008 (UTC)

Bone Cartilage

We all know that nothing can really change bone from the hard shell that it is, even with many years discoveries of cavemen's bones have remained hard and sometimes in tact. But is there anything that can change a bone form, make it soft or flexible? Change the properties of a bone? —Preceding unsigned comment added by 67.127.172.138 (talk) 04:07, 11 April 2008 (UTC)

You might want to read our article on osteomalacia, which essentially is soft bones. Wisdom89 _{(T / ^C)} 04:13, 11 April 2008 (UTC)

Bones are made of large amounts of collagen. Reasonably fresh cadaver bones can be decalcified by placing them in a solution containing a cation chelator, such as EDTA. I've seen a tibia treated this way tied in a knot. It was used during Anatomy lectures to demonstrate that bone is not just mineral. -- Flyguy649 ^talk 04:15, 11 April 2008 (UTC)

I would like to correct one mistaken assumption in the question. Most bones do decay over time, although more slowly than the rest of the body (it may take centuries versus months for the rest). We rarely find old bones in water, for example. However, in the right conditions, bones can last for thousands of years. Those "bones" that are millions of years old, however, are usually not actual bone, but minerals which have replaced the original bone to form a fossil. StuRat (talk) 13:57, 11 April 2008 (UTC)

A fun experiment you can do for yourself is to drop the bone from your next chicken drumstick into a cup of vinegar and let it sit overnight. The next day you'll be able to tie it in a knot. When it dries out, it will get hard again, and you can amuse your friends with the tale of the deformed chicken leg you ate. Not as impressive as doing it with a human femur as Flyguy mentions, but not all of us are lucky enough to be able to play with human remains. :) --Sean 14:37, 11 April 2008 (UTC)

Boneitis might have some interesting efects on your bones. 81.96.161.104 (talk) 20:18, 11 April 2008 (UTC)

Would the bones if you softened like the chicken or drumstick in vinegar, would it ever become harden again? —Preceding unsigned comment added by 69.231.29.227 (talk) 01:06, 12 April 2008 (UTC)

Yes. I think rinsing the vinegar off and waiting is all you need to do. StuRat (talk) 03:19, 12 April 2008 (UTC)

No I don't think it would, I remember reading somewhere that if you soak a bone in water for a very long time the calcium gets dissolved and the bone goes all springy and soft. And if you burn a bone it goes all brittle and is very easy to snap.--Phoenix-wiki 12:20, 13 April 2008 (UTC)

Determining the Acidity of a molecule

I've read some conflicting advice on how to determine the acidity of a molecule. One thing I read stated that the acidity of an acid is directly proportional to the electronegativity. Another source I read though, however said that HF is weaker than HCl because the electronegativity of HF is so high that it does not want to disassociate in water. Which one is correct? Thanks. —Preceding unsigned comment added by Legolas52 (talk • contribs) 05:31, 11 April 2008 (UTC)

It how easy the molecule gives up H⁺, particularly when in water. It is not directly connected with the electronegativity of the element involved. Helium hydride is a very very strong acid. Graeme Bartlett (talk) 07:16, 11 April 2008 (UTC)

Male/female blood?

According to this Discover magazine article, a male cancer patient received a bone marrow transplant and now has "100 percent female" blood. What is the difference? Clarityfiend (talk) 05:56, 11 April 2008 (UTC)

Likely that all the white blood cells (and red blood cell precursors) have XX (from the donor) instead of XY (from self) -- Flyguy649 ^talk 06:06, 11 April 2008 (UTC)

Yes, and the difference would be apparent to anyone who examines the man's peripheral blood smear (as would be done in a complete blood count or white blood cell differential count), because the inactivated Barr body in female cells could be seen in the white blood cells as a drumstick-like projection from one of the lobes of (about 3% of) the neutrophils. There would be no difference in the peripherally circulating red blood cells because, in humans, they have no nuclei. - Nunh-huh 06:16, 11 April 2008 (UTC)

Oh, and functionally, I can't see how there would be any difference between male and female blood. -- Flyguy649 ^talk 06:27, 11 April 2008 (UTC)

Probably none, although there are more or less significant range disparities between males and females on CBC counts. Wisdom89 _{(T / ^C)} 06:33, 11 April 2008 (UTC)

So if he comitted a crime, the Crime scene investigators would be fooled into looking for a female suspect if they found traces of his blood left at the crime scene? Edison (talk) 14:23, 11 April 2008 (UTC)

Yep. For a related situation, see chimera (genetics) and the case of Lydia Fairchild. TenOfAllTrades(talk) 16:00, 11 April 2008 (UTC)

Red blood cells have no cell nuclei and thus have no DNA. Therefore, there is no "XX" or "XY" chromosome to distinguish a red blood cell as male or female. As Nunh-huh mentioned, some other blood cells may be identifiable. Nimur (talk) 16:10, 11 April 2008 (UTC)

Well, yes—others have already noted that above. The blood is '100% female' inasmuch as all of the cells that do carry distinguishing genetic material will be XX and not XY. It takes a vanishingly small amount of blood to get a nucleated (white) blood cell, too. Even though erythrocytes (red blood cells, with no nuclei) outnumber leukocytes (white cells, with nuclei and genomic DNA) by about a thousand to one, there are still five or ten thousand such nucleated cells in every microliter of blood. TenOfAllTrades(talk) 17:13, 11 April 2008 (UTC)

Faraday cages

Does anyone know how close together the wires in a wire mesh would have to be before it would act as a Fahrady Cage? I just wonder because I noticed I don't get mobile phone reception while stood inside a cricket batting cage, even though the wire is inches apart. Also if the wire was insulated bit still quite dense would it still act as a cage? If I wrapped my mobile phone in tinfoil would I still get a singnal or would the metal have to be a certain thickness?

Just as an aside why don't the type of people who wear tinfoil hats use chainmail helmets instead :D? TheGreatZorko (talk) 09:17, 11 April 2008 (UTC)

The rough rule of thumb is that the wire have to be closer than one tenth of the wavelength, so the 20cm wavelength 1500MHz mobile phone, will need about 2cm spacing, and the phone cannot be too close to the mesh either otherwise it will get ephemeral waves bleeding through. Thin metal will work musch the same as thick metal, so foil should block a mobile phone. You have to look at the skin depth. Very low frequencies can penetrated deeply into the conductor. So earths magnetic field will make its way through. (A super conductor will have 0 skin depth). Also you have to completely enclose the item, so a hat will not work, has to be completely encased! Graeme Bartlett (talk) 09:36, 11 April 2008 (UTC)

Also, the rings in the chain mail may not be making sufficiently-good electrical contact with each other to ensure forming a good Faraday cage. The odd and variable points of contact, corrosion of the metal, and the buildup of grease and other insulators will all combine to allow some of the signal from Faux News to slip into your brain.

Atlant (talk) 12:28, 11 April 2008 (UTC)

If what you say is true, then the rings in chain mail would seem to operate by the electrical perversity principle: if two pieces of metal touch and you want them to conduct electricity, they are less likely to than if you do not want them to conduct electricity. Two wires with frayed insulation touch, however lightly, and a short circuit blows a fuse or starts a fire. Two pieces of metal touch and you want them to provide shielding in this case, or to conduct electricity in other cases, like a poorly adjusted relay, a worn switch, a vacuum tube in a loose socket, or a multi pin connector, and they act like an open circuit. Edison (talk) 14:20, 11 April 2008 (UTC)

Precisely!

Atlant (talk) 17:53, 11 April 2008 (UTC)

Also, a chain mail hat is more expensive and less readily available at home than tinfoil. – b_jonas 10:29, 14 April 2008 (UTC)

what is charge?

We've all heard of the positive and negative charges, but at the most basic,smallest level, what is it? Why does an electron repel another electron, while it attracts a proton?? why is it negative or positive? what is it exactly? What constitutes charge at the smallest level? (In protons, I've heard of quarks with partial charges, but why is it charged at all???) 116.68.70.147 (talk) 10:33, 11 April 2008 (UTC)A 15-Year Old

Good question. The short definition is that electric charge is a fundamental conserved property of some subatomic particles, which determines their interaction with electromagnetic fields - see electric charge. But of course we then define an electromagnetic field as a field produced by and affecting objects with electric charge. So that's a circular definition. I think the longer answer is that we don't know exactly what electric charge is, but it has proved to be a useful concept in physics, both because of its fundamental nature (it is not an emergent property like, say, pressure or temperature) and because it is conserved. The positive/negative nature of the electric charge is not inherent to the concept of charge - the color charge, which determines how sub-atomic particles interact with the strong force, comes in three flavours, rather than two. Gandalf61 (talk) 12:01, 11 April 2008 (UTC)

But the word "charge" in colour charge is misleading. The article uses an analogy, but quark colour has no connection with electrical charge. The positive/negative nature of the electric charge is inherent to the concept of charge in normal scientific usage. 78.32.74.48 (talk) 16:44, 12 April 2008 (UTC)

The role of electric charge in quantum electrodynamics is very similar to the role of colour charge in quantum chromodynamics. Together with weak isospin, they make up the three charges in the Standard Model of particle physics. Our article on charge makes this clear. When particle physicists refer to "charge" they may mean any one of several conserved quantum numbers that are associated with particle and field symmetries. Gandalf61 (talk) 17:34, 12 April 2008 (UTC)

Erasing Bad Relationship

Just like in the movie Eternal Sunshine of the Spotless Mind, is it possible in the future to remove a bad memory from your brain? I am experiencing a horrible heartbreak and I would like to know if anything remotely exists right now --Jonasmanohar (talk) 14:08, 11 April 2008 (UTC):

Answer:

--Sean 14:46, 11 April 2008 (UTC)

how about other than that? --Jonasmanohar (talk) 14:52, 11 April 2008 (UTC)

Right now, there's nothing like Eternal Sunshine in real life, although really heavy drinking to induce brain damage might work. The problem is you'd have nocontrol over what you forget, and it's as likely to be the alphabet as it is your realtionship. I don't recommend it. 81.96.161.104 (talk) 15:23, 11 April 2008 (UTC)

Also, this is seriously bordering on asking for medical advice, which Wikipedia can not give. If you are having a hard time over this, see a doctor or possibly a therapist. -- MacAddct  1984 ^{(talk &#149; contribs)} 15:49, 11 April 2008 (UTC)

Removing only one memory is probably impossible because one memory builds on several other memories. If you remove it, you will mess with the other memories too. What is certainly possible is removing a whole class of memories by performing the appropriate brain lesion, and then starting afresh. This is called Retrograde amnesia. You will have no memory of you lover but probably also a whole lot of other stuff - like your friends and family too. It has probably been done on animals, but the procedure is so debilitating that no doctor will perform it. The best you can do is hope for a stroke. Probably better just to let the memory fade with time. Cambrasa 19:53, 11 April 2008 (UTC)

Dear Jonas, I fear the damage is done. By writing and discussing your wish to rid yourself of a bad memory you surely will, by dint of the mystery known as the human mind, remember it forever. I am so sorry. Richard Avery (talk) 21:45, 11 April 2008 (UTC)

There are experimental techniques being tested for selectively modifying memory. However this research in mainly intended to help solders or rape victims. People who are in great danger of developing posttraumatic stress disorder. It is unlikely that such technology will ever be available for casual civilian use. Painful as such breakups may be, they are a necessary part of life. Erasing the memory of the relationship would in the long run probably harm you. (Read Brave New World for an interesting take on this.) --S.dedalus (talk) 22:49, 11 April 2008 (UTC)

You know, there's a better avenue than seeking to erase your memories: truth and reconcilation. Reflection and introspection will, over time, shed new light on past experiences that you may want to label 'bad', and you will eventually understand them as opportunities for growth and improved wisdom. Vranak (talk) 00:03, 12 April 2008 (UTC)

Believe it or not, that time heals is attested to throughout human experience. Distraction is used in pain management and healthy ones not only help you endure the time but give you fewer regrets/health issues when you pass through it. Julia Rossi (talk) 01:32, 12 April 2008 (UTC)

Re Richard A's comment about reinforcement, true enough, but remembering forever is not quite the same as feeling the same forever since discussion and interaction can change the feeling or the intensity and I take it your question is mostly about linking pain and memory. See our articles on Perspective (cognitive) and Perspective (psychological). Julia Rossi (talk) 01:42, 12 April 2008 (UTC)

Light Reflection

I was sitting in front of my patio door last night while it was raining. The patio was very wet and the a light on my neighbor's porch was lit. There is also a privacy fence between our patios, but it doesn't span the entire patio. As I sat there I could see the light reflecting off my patio. When I moved a few inches to the right, the reflection was gone. I could no longer see the light either because it was being hidden by the fence. I understand line of sight and that light doesn't normally bend around objects, hence I couldn't see the light anymore, however, the spot where the reflection was on the patio was definitely in my line of sight still. Neither the patio, fence, nor light moved, so the reflection must still be there, but I couldn't see it. I did read the article on reflections and I think there is something I'm not understanding about angles because my angle was still the same, at least vertically, so wouldn't I still be able to see it? Is there a horizontal angle? Why was I unable to see the reflection still even when it's in my line of sight? —Preceding unsigned comment added by Beckerj99 (talk • contribs) 14:11, 11 April 2008 (UTC)

I'm not sure I'm picturing this properly so could be on the wrong track (a diagram would really help!), but here goes. Because the patio is very wet it essentially provides a smooth surface resulting in regular reflection like with a mirror - when the light reflects from the patio it stays in the same plane, essentially meaning it follows that straight line direction. When you move sideways blocking the light you're obscuring that plane at the reflected surface as well (think about a huge sheet of glass between yourself and light; as you moved to the side, moving the glass with you, would that sheet of glass have intersected the fence?). Looking to the spot where you could previously see the reflection is no good, because you're no longer in that plane, and the spot where you would now see the reflection is blocked by the fence. Now is the reflection still there, in that spot? Sure, it's just that since you're no longer in the same plane as it you don't see it - if you stand in front of a mirror you see your reflection because you're in the same plane, but move to the side and you can't see yourself; nonetheless your reflection is still there as someone who's at the other side can see it from there, and you can see them. It's basically this principle. Hope this helps. --jjron (talk) 16:41, 11 April 2008 (UTC)

What might help is trying to think of--instead of all the paths the light can travel--both the light and the blocking wall as having mirrored duplicates on the other side of the plane of the patio (assumed to be a horizontal reflective surface). Effectively, this means an imaginary wall extending from the level of the patio down a length equal to the real wall's height above the patio and a light similarly below the position of the real light. Looking through the puddle at these imaginary objects, would the imaginary wall block your line of sight to the imaginary light? ASCII art:

your eyes -> oo                         O <- real light
                                 |
                                 | <- real wall
patio -> ________________________|__________
                                 |
                                 | <- imaginary wall
                                 |
                                        O <- imaginary light

If the patio were reflective enough and the environment well enough lit that you could clearly see the reflected outline of the wall, it would probably be less confusing a situation. --Prestidigitator (talk) 20:35, 11 April 2008 (UTC)

Radar Site By The M27 In Hampshire England??

Just to the north of the M27 motorway between Southampton and Portsmouth I have seen a Radar tower that is clearly visible from the road. The tower looks just like the new Samson Radar for the Type 45 destroyers http://en.wikipedia.org/wiki/Image:HMSDaring.jpg

I have looked on the maps, google earth and searched the Internet but can find no mention of the site and what it is. Is does look very much like the mask and radar from the new destroyer?

Its very much a local question so feel free to move. —Preceding unsigned comment added by 86.4.182.208 (talk) 15:39, 11 April 2008 (UTC)

Could it be a cell(mobile)phone tower? -- MacAddct  1984 ^{(talk &#149; contribs)} 15:58, 11 April 2008 (UTC)

No chance. Its just like the tower with the dome on top as the type 45 destroyer. Its nothing like any other radar or communication site I have seen before.

You have a good eye. You should be a spy. It is just what you thought, the SAMPSON radar for the Type 45 destroyer. A test facility belonging to BAE, maker of the radar, sits atop Portsdown Hill just north of Portsmouth Harbour. There is a paper about the ship here that mentions the facility. --Milkbreath (talk) 17:41, 11 April 2008 (UTC)

Micro wave cooking

I had a discussion with a co worker recently who claimed that cooking with a micro wave changes the DNA of what it cooks and is very bad for your health. He also told me that he had his sons perform an experiment where they boiled distilled water on a stove and another sample in a micro wave and used each to water 2 plants. After3 weeks the plant watered with the micro waved water died. Why would this happen?129.112.109.253 (talk) 16:34, 11 April 2008 (UTC)

Some, or possibly many, people have basically unfounded paranoia about microwaves - I know some people that won't use them as well, and it sounds like your co-worker is at the extreme end. There's plenty of fringe literature to bolster these fears, but basically there's no reputable studies that show any significant risk AFAIK; refer to Microwave#Health_effects for starters. Re the plant 'experiment', well it sounds like he's seeing the results he wants to see; I'd be asking for some better evidence than his anecdotal test. --jjron (talk) 16:54, 11 April 2008 (UTC)

Sounds like a reasonable experiment to try, except as stated it might have been subject to Experimenter's bias in that the experimenter might have known which plant was getting the microwaved water and had an expectancy that the other would do better. Overwatering, drying out from too much sun, using water that is still too warm from the boiling or other variations in the treatment of the plants could cause one to die. The brief description of the experiment also says "a plant." A rigorous experiment would use multiple plants to allow for the fact that there is inherent variation in how well a plant grows. A Blind experiment would have coded labels on the water and the plants so that the person watering the plants would not know which plant received which water supply. A better experiment would have several plants which were randomly assigned to groups, to avoid the experimenter selecting the healthier plants for the favored group. The measures for which plant is healther should be established in advance and objectively measured, to avoid after the fact selection of height, weight, or color as the measure because the favored plants were best at that measure. The final determinant is replicability in other labs which do not share the biases or expectations of the original experimenter. Edison (talk) 17:05, 11 April 2008 (UTC)

This article on the effects of microwave ovens is probably more appropriate. -- MacAddct  1984 ^{(talk &#149; contribs)} 17:13, 11 April 2008 (UTC)

(ec)As to the DNA, that's complete and utter nonsense. Microwaves are non-ionizing radiation they can't change DNA, and even if it did, whatever you're cooking is dead, its cells aren't dividing, it isn't producing new proteins, it's completly inert. That argument makes me immediately discount any other findings he states since he sounds like he is just throwing out words to sound scientific. 192.45.72.26 (talk) 17:19, 11 April 2008 (UTC)

This article is the number 3 google hit for "microwaves", so your fearful friend is in good (or at least plentiful) company. In it I learned the following:

1. "use of artificial microwave transmissions for subliminal psychological control, a.k.a. "brainwashing", has also been proven"
2. you should not microwave your blood
3. microwave ovens cause "a breakdown of the human "life-energy field"", and lead to "magnetic deposits" in the lymphatic system
4. microwave ovens' use of alternating current is what makes them dangerous, while the sun's microwaves are safe because they operate on direct current

--Sean 17:37, 11 April 2008 (UTC)

Wow, that last one made me snort out loud at my desk. Luckily everybody else seems to have gone home early! --LarryMac | Talk 18:20, 11 April 2008 (UTC)

You can also buy an economy size order of bioTHIN, algae pigment guaranteed to make you loose weight, happy days! -- MacAddct  1984 ^{(talk &#149; contribs)} 17:46, 11 April 2008 (UTC)

If you run the experiment until one of them dies, then even if the experiment is conducted perfectly, there's an expected 50% chance that'll be the one you're interested in. To prove that microwaved water is dangerous (to plants) you'd need to show that the microwaved water plants died more often than could be attributed to random chance. An the double-blind requirement mentioned above would be important too.APL (talk) 17:59, 11 April 2008 (UTC)

Also, using more than 2 plants would be beneficial too. To be statistically significant, you would probably need a sample size of at least 30. -- MacAddct  1984 ^{(talk &#149; contribs)} 18:09, 11 April 2008 (UTC)

Over time, microwave ovens may also affect your Purity of Essence/Our Precious Essence. Seriously, your friend's concerns are, ahem, overstated.

Atlant (talk) 18:00, 11 April 2008 (UTC)

Are we talking about that big clock that sometimes cooks things? 200.127.59.151 (talk) 19:50, 11 April 2008 (UTC)

The DNA argument is nonsense. Any DNA you ingest will be broken down in your stomach, so whether it is broken down beforehand or not, it makes no difference. Also, the food in the oven is no longer alive, and the DNA is no longer being used to make proteins, mutated or not Cambrasa 19:59, 11 April 2008 (UTC)

I find tea made with water boiled in a kettle to have a more agreeable taste than with water boiled in the microwave. It's a more natural experiment than buying two plants and feeding them water over two weeks. Nevermind scientific literature – try it yourself for first-hand knowledge. Vranak (talk) 00:01, 12 April 2008 (UTC)

Or maybe it's just placebo effect. --antilived^{T | C | G} 00:42, 12 April 2008 (UTC)

Or maybe it's not. Vranak (talk) 01:33, 12 April 2008 (UTC)

When doing taste experiments I strongly recommend blinding. Experience shows that many people will be convinced that something tastes better just by e. g. some clever advertisement and a higher price. You'll also find some examples of this if you search with Google Scholar. Icek (talk) 01:52, 12 April 2008 (UTC)

I am aware of the double-blind with-placebo experiment and its uses. That said, I know a funny taste when I taste it. Vranak (talk) 05:08, 12 April 2008 (UTC)

One possible explanation that occurs to me is that water boiled in a microwave could have fewer impurities than water boiled in a kettle, and so could taste different. What does the inside of your kettle look like ? Gandalf61 (talk) 08:44, 12 April 2008 (UTC)

I have noticed the effect that Vranak mentions. I put it down to smells adsorbed on the steel lining of the oven, or perhaps lurking in the numerous crevices in the interior. If I put my head right inside the oven (who doesn't?) I can detect this smell, which never goes away regardless of how carefully I clean the thing. It smells like all 57 varieties of soup mixed together. After all, it's pretty unnatural to cook food in a tiny steel box that never gets a proper clean - it never gets immersed in hot soapy water like a pressure cooker or saucepan, or roasted at 200 °C like a conventional oven. I certainly wouldn't blame the taste on some undocumented property of the Deadly Radiation. What's your hypothesis, Vranak? --Heron (talk) 09:30, 12 April 2008 (UTC)

It's been about four years since I've had tea made with microwaved water, so it's hard to recall. I think the water just feels 'buzzy', it's not so much a matter of flavor. Vranak (talk) 23:49, 12 April 2008 (UTC)

I'd go along with the "absorbing smells from the microwave oven's interior" hypothesis. I suppose a "microwave kettle" could be made, perhaps out of glass, that would be sealed until the water boils, then would whistle as it let's the steam out. A glass bottle with a small opening would be a good compromise until such a device becomes available. Always avoid microwaving water in plastic, as it may absorb chemicals that leach from the plastic when heated. StuRat (talk) 15:17, 12 April 2008 (UTC)

Then again, so does everyone who experiences the placebo effect, do they not? That said, I'm not denying the possibility of your experience, simply suggesting without a double blind, we will never know whether it's a true difference or a placebo... Bear in mind any good experiment will also need to take into account all possible factors. Water same temperature, brewed for the same time, using similar tea bags, your are in same condition etc (ideally the person doing the brewing should be single blind). For example, if you only make tea from microwaved water when you are in a hurry then there are obviously many possibilities as to why the tea thats different. Nil Einne (talk) 17:38, 12 April 2008 (UTC)

You seem to be suffering from the scientist's classical delusion that anything can be finally regarded as 'true' or 'proven'. Such thinking is vanity. "There are no moral facts, just as there are no eternal truths." -- Nietzsche. Vranak (talk) 23:52, 12 April 2008 (UTC)

Is someone forgetting mathematics? But about the microwaving of tea, I've never noticed an odd taste when I reheat tea in the microwave but, like you Vranak, I do when I make it in the microwave. I think it's because the microwaves mess with the teabag, but that's just OR. Michael Clarke, Esq. (talk) 00:04, 13 April 2008 (UTC)

Hi. Keep in mind, however, that just because something hasn't been proven doesn't mean you shouldn't at least be a bit cautious. Thanks. ~AH1^(TCU) 01:23, 13 April 2008 (UTC)

Wait, you were microwaving the water with the teabag in?! No wonder it tasted weird. I'd also imagine, making the tea properly, there'd be a difference with microwaving the water vs boiling in the kettle because it's harder to get the water evenly boiling in the microwave. A decent cup of tea requires freshly boiled water poured onto the tea while still as close to 100°C as possible. 79.66.105.94 (talk) 01:27, 14 April 2008 (UTC)

Vranak, if you didn't do it double-blind then you couldn't possibly know if it really tasted different. People report that heavy water tastes totally totally different than regular water if they know it's heavy water. If they don't, they say it tastes like regular water. The mind is a subtle thing, and taste is even more subtle—color, smell, and expectations can change how things taste a LOT. I read recently of an experiment in which a researcher gave people beer with red wine vinegar; when they didn't know what the additive was, many of them claimed to enjoy it, when they knew what it was, they all said it tasted disgusting! Don't stick by your perceptions unless you have some reason outside of them to believe it. Microwaved water shouldn't have a different taste—if you don't expect it to, you probably won't find one. I used to think I could taste the difference between all the different colors of Froot Loops until I actually tried it with my eyes closed once and realized they were all identically ambiguously fruity! --Captain Ref Desk (talk) 05:15, 13 April 2008 (UTC)

As a person who still seems to have full faith in science, I shouldn't expect that we'll be able to come to an understanding. So, we'll have to agree to disagree for now. :) Vranak (talk) 15:54, 13 April 2008 (UTC)

You haven't the slightest ideas what my opinion on science in general is. What we're talking about here is just reasoning about what makes a logical conclusion and what's a good way of coming to it. If you want to throw out reason, please feel free, but if you're going to do that I hardly see what benefit your contributions are going to be. As for the question of whether microwaved water tastes different from non-microwaved water, it's easy to come up with reasonable, reliable, and reproducible results. Your method is obviously not the way to do this, and watching you sticking by it even in the face of its obvious methodological difficulties makes me wonder if you are ignorant or just stubborn. --Captain Ref Desk (talk) 00:00, 14 April 2008 (UTC)

Captain Ref Desk your above reply to Vranak is out of line. In particular saying “if you're going to do that I hardly see what benefit your contributions are going to be” is borderline personal attack. After all 86% of people in the world believe things without evidence. -- S.dedalus (talk) 21:48, 14 April 2008 (UTC)

In support of the good Captain, you've taken it slightly out of context there. He said "If you want to throw out reason", which is a valid complaint, really. Conclusions reached without the use of reason are significantly less valuable. And just because the majority of people do something, that doesn't mean it's the right thing to do. The Captain had a valid point about the reliabilty of conclusions drawn from experiments performed at home with no control measures, and to suggest that we should accept answers to queries posted here that are clearly not based on the principles of logic and reason simply because a lot of people hold beliefs that do not stand up to scientific scrutiny is ludicrous. Sorry if I'm a bit blunt but I really fail to see the problem with Cap Ref Desk's comments. Michael Clarke, Esq. (talk) 22:02, 14 April 2008 (UTC)

Vranak: Science doesn't work on "faith", nor does it aim to "prove" anything. All a scientific experiment does is corroborate a claim, or falsify it. That's a far cry from "proving" a claim. In this case, it's perfectly valid to demand an unbiased experiment to support or falisify a claim, in this case the claim is that tea made with microwaved water tastes different than tea made with water boiled in a kettle on a stove.

It's perfectly fine to have faith in one's own senses, but even professionals in the wine tasting business know that their sense of taste is easily altered by other influences such as color, knowledge of price, brand, etc. -- which is why California wines didn't win competitions in France until the blind tasting Judgment of Paris. Until one actually experiences the brain's influence on flavor perceptions, there's no point criticizing a proposal for a simple experiment. ~Amatulić (talk) 22:23, 14 April 2008 (UTC)

“Comment on content, not on the contributor.” (Wikipedia:No personal attacks) and “Wikipedians define incivility roughly as personally targeted behavior that causes an atmosphere of conflict and stress.” (Wikipedia:Civility) At the very least Captain Reference Desk’s remarks seem highly argumentative. He could just as easily have let it go and ended the discussion amiably as Vranak seemed to be trying to do. It doesn’t matter whether Vranak is right or wrong. We would never say to an editor “Because you are a Presbyterian I hardly I hardly see what benefit your contributions are going to be.” Yet to a scientist most Christian beliefs are as illogical as microwaves changing the taste of water. Vranak is entitled to hold his beliefs without harassment. --S.dedalus (talk) 22:40, 14 April 2008 (UTC)

Fellows, there are plenty of scientists who do believe in God, just as some believe in UFOs. You probably believe Ceasar's account of his conquest of Gaul, yet the oldest manuscripts of his account are from around the 13 century and there are only 5 of them. There are over 5,000 manuscripts are or manuscripts of books of the Bible, many dating back several thousnad years. 129.112.109.250 (talk) 16:33, 16 April 2008 (UTC)

Earth Hour

Most of my appliances have a wattage or amperage rating. For instance, my microwave has a rating of 500 watts and my room AC has a rating of 5,000 watts. It takes 3 minutes, 33 seconds for the microwave to heat up a 900 ml container of water from 72.1 F to 138.4 F, raising the temp by 138.4 - 72.1 = 66.3 degrees Fahrenheit. I've used .5 kW for (3 + (33 / 60)) / 60 = 0.0591666667 or 0.0295833334 kWh. The cost of my electricity is

• Energy Charge $.05061/kWh
• Fuel Charge $.05241/kWh
• Total Charge $0.10302

So it costs me 0.0295833334 kWh x $0.10302 or $0.003047675 or about a third of a cent to heat water to make coffee using electricity. However, it costs me $0.07625 to burn 1 ounce of Isopropyl during Earth Hour at $2.44 per 32 oz. So if I want coffee during Earth Hour using Isopropyl to heat the water it will cost me 25 times as much.

What then is the least cost, yet most convenient, replacement for electricity I can use to heat water during Earth Hour? (Not a homework question BTW although it should be.) 71.100.160.37 (talk) 17:50, 11 April 2008 (UTC)

Only you may be able to answer the question about convenience, but in terms of low cost and most environmentally friendly/efficient, consider perhaps a solar cooker. May not work in all climates and times, so I guess that could reduce your measure of "convenience". :-) --Prestidigitator (talk) 20:43, 11 April 2008 (UTC)

Generally speaking, the least expensive thing is the most environmentally friendly. If it costs 25 times as much to cook it with isopropyl, that probably reflects it being more labor-intensive to get, or simply less efficient. If it's less efficient, then you're burning less to get the electricity to heat the coffee then you are if you heat it by burning isopropyl. If isopropyl is more labor-intensive to get, that labor is using some form of energy (electricity, gas, etc.) that's presumably environmentally unfriendly. If you want to be able to tell people that you did your part to help the environment by observing Earth Hour, use the stove. If you want to actually do your part, rather than telling people you did, use the microwave when it's more efficient, and conserve energy in ways that actually do something. — DanielLC 22:02, 11 April 2008 (UTC)

If you want to go really old-school, you could try a wood burning stove, or just a small wood fire. That'll heat water pretty fast. Michael Clarke, Esq. (talk) 01:53, 12 April 2008 (UTC)

Or indeed the Kelly kettle. Ingenious design! BrainyBabe (talk) 19:36, 16 April 2008 (UTC)

Thanks for the suggestions. I've taken a second look and have decided the best way to provide myself with coffee during Earth Hour is to, er... to make a lot more of it in the microwave before Earth Hour starts and store it in a thermos until Earth Hour is over. 71.100.160.37 (talk) 04:16, 12 April 2008 (UTC)

That was going to be my suggestion. This question brings up, however, flaws with the concept of Earth Hour. If people switch to less efficient forms of energy or use more energy before and after Earth Hour, this really doesn't help the environment, does it ? I object to "feel good solutions" which do nothing to actually solve the core problem. Replacing incandescent light bulbs with compact fluorescent bulbs is an example of something everyone can do which will actually save energy, versus this Earth Hour silliness, which does nothing to save energy. What's worse, people who participate in Earth Hour will then say "hey, I've already done my part, no need to go changing light bulbs, too". I almost wonder if Earth Hour wasn't started by some oil company to intentionally distract people from actually doing anything that will really save energy. StuRat (talk) 15:00, 12 April 2008 (UTC)

Hey, now there is a thought... Earth Hour Revised - ride the bike to work instead of the SUV. 71.100.160.37 (talk) 16:41, 12 April 2008 (UTC)

Yes, that would actually do some good. I used to walk to lunch every day rather than drive. StuRat (talk) 03:16, 13 April 2008 (UTC)

The emphasis of Earth Hour is on switching off lights, as hinted at by the official slogan 'See the difference you can make'. The organisers do not suggest that anybody go without hot food. Their website also recommends [3] using compact fluorescent bulbs, as mentioned by StuRat. I think that most of the points made above are straw men - "Look, I had to burn polar bear cubs to keep warm during Earth Hour: how environmentally friendly is that?"

Actually they no longer need to recommend using compact fluorescent bulbs since retailers have begun selling low cost incandescent bulbs that may say 1000 hours but that are lucky in some cases to make it to 300. Of those bulbs you might be considered lucky for only one out of ten to pop on first use. 71.100.160.37 (talk) 05:01, 14 April 2008 (UTC)

Earth Hour is a just a stunt to make people think about their energy usage for a few days. It isn't going to save the planet (assuming that it needs saving), but as a piece of agitprop it works just fine. --Heron (talk) 13:02, 13 April 2008 (UTC)

I look at it as people having a finite amount of effort they will put into any endeavor, in this case saving energy. If they waste that effort on "Earth Hour", they will take less of an effort on other actions that will make a permanent difference in energy usage. Even if Earth Hour was a huge success (reducing energy usage by 10% during that hour and not increasing energy usage before or after to compensate), that still would only result in around a 1/1000 of 1% reduction in energy usage for the year. StuRat (talk) 15:14, 13 April 2008 (UTC)

Actually we do already have Car Free Days in some places Nil Einne (talk) 13:19, 13 April 2008 (UTC)

Cheap nuclear power ?

Okay, maybe I should post this as a new question but here goes... What about nuclear fusion that was suppose to make the cost of electricity so low it would be too cheap to meter so we would not need to conserve? 71.100.171.178 (talk) 03:29, 14 April 2008 (UTC)

(I made it a subquestion instead.) That seems absurdly optimistic to me. Even if energy could be produced absolutely freely, the cost of distributing it via power lines and maintaining those lines alone would be worth metering, unless you want to broadcast electricity as Tesla envisioned (with people occasionally bursting into flames if their fillings happen to pick up that frequency). At present we can't even make net energy from fusion at any price. It may provide a low cost energy source several decades from now, but certainly not that low. StuRat (talk) 18:21, 14 April 2008 (UTC)

Here's a really good article on the subject. The phrase comes from a speech made in 1954 and is now a byword for unfounded scientific optimism. The world at that time was full of daft predictions, so it's a bit unfair to single out this quote, as some people do, as if it underpinned the modern nuclear industry. The guy didn't even say that nuclear power would be source of this cheap electricity, although that's what most listeners would have inferred. --Heron (talk) 14:00, 15 April 2008 (UTC)

Well, he meant it as nuclear. He was Lewis Strauss, chairman of the AEC, all-around atomic blowhard. Strauss was only doing his normal thing: being totally unrealistic in his scientific advice and happily defying people who knew better. After Sputnik, Eisenhower finally realized that Strauss's scientific advice was so bad that he decided to set up better ways of getting it (ergo the birth of PSAC). --98.217.8.46 (talk) 02:50, 13 September 2008 (UTC)

What elements glow green?

I understand spectral analysis shows the colors different elements emit. What elements emit the color green? This includes all shades of the color from blue-green to yellow-green to just plain green. (you don't have to include compounds.) Am I right in saying, first of all, that Oxygen appears green? If you look in the sky with a telescope and see a green mass, what does that tell you about the object chemically? Wrad (talk) 22:20, 11 April 2008 (UTC)

A great example of an element emitting green, or rather, appearing green is Chlorine gas. Wisdom89 _{(T / ^C)} 22:36, 11 April 2008 (UTC)

Also, Oxygen is a colorless gas. Wisdom89 _{(T / ^C)} 22:37, 11 April 2008 (UTC)

Hi. Does Copper count? Apparently it glows green when fired. BTW I'm not an expert on this. Thanks. ~AH1^(TCU) 23:35, 11 April 2008 (UTC)

I've seen copper mentioned, yes. Wrad (talk) 23:37, 11 April 2008 (UTC)

He's right, oxygen does have a green 5007 Å emission line. You see it in nebulae and aurorae. -- Coneslayer (talk)

Does Chlorine emit green or does it just absorb all but green light? Wrad (talk) 23:58, 11 April 2008 (UTC)

I think Chlorine just reflects green. I'm not sure of it's spectral properties. Wisdom89 _{(T / ^C)} 01:28, 12 April 2008 (UTC)

... Or a pale blue liquid: liquid oxygen. -- 128.104.112.85 (talk) 20:27, 12 April 2008 (UTC)

If you want pure green try burning some thallium. 71.100.160.37 (talk) 00:24, 12 April 2008 (UTC)

And the anon is absolutely correct. Wisdom89 _{(T / ^C)} 01:30, 12 April 2008 (UTC)

And with emission spectra, as in the flame test, barium and boron will make a green flame. At that article you can see a few more greenish elements. Graeme Bartlett (talk) 12:15, 13 April 2008 (UTC)

April 12

Asexual Reproduction and Natural Selection

I recently learned from a video that some lizards and fish reproduce asexually. I was wondering what is preventing these species from becoming extinct since without sexual reproduction, all the individuals of the species are genetically identical clones. So a virus could kill all of the asexually producing lizards, but only some of the sexually producing ones, since the sexually reproducing ones will have genetic variation. Since the asexual lizards can't adapt to their environments as a population, aren't they at an ultimate disadvantage to a population that can evolve? I know that there are some advantages to asexual reproduction, but how can a population that can't evolve survive in the same environment as one that does, what with natural selection? 24.13.115.247 (talk) 00:01, 12 April 2008 (UTC)

I don't know much about the subject, but I would think that genetic mutation would still occur in assexual reproduction, but that the gene pool in general would indeed be a lot less varied. So I imagine they are not all identical clones of one another, although they likely have less diversity than other species that reproduce sexually. Michael Clarke, Esq. (talk) 01:52, 12 April 2008 (UTC)

Many species (notably bacteria) reproduce exclusively asexually . Other species (e.g. mammals) reproduce exclusively sexually. There is a vast middle ground, where sexual reproduction is used when a male is available, but asexual reproduction is used when no male is available. This makes obvious evolutionary sense: when no male is available, the female that requires a male has no offspring, while the female that does not require a male does have offspring. -Arch dude (talk) 02:07, 12 April 2008 (UTC)

Yeah, if anything, sexual reproduction is the deviant method. It's very tricky to justify. For example, why are there two sexes and not anyone with anyone else, as some species do? Imagine Reason (talk) 03:20, 12 April 2008 (UTC)

The anon is right, a single virus or disease can wipe out an asexually producing species. See Banana#Pests.2C_diseases_and_natural_disasters to see how damaging a single disease is to a asexually produced organism. Perhaps the lizard that you mention is just lucky. A sudden change in the environment our an outbreak will wipe them out.--Lenticel ^(talk) 14:23, 12 April 2008 (UTC)

As noted previously, mutation is the key to survival. This is true in sexually reproducing species as well, since sex only produces "variation within a range", not entirely new characteristics. Species can also apparently vary their mutation rate. Here are some advantages and disadvantages to a high mutation rate:

1) The obvious advantage is that it allows for quicker evolution, both on a small scale, to develop an immunity to a disease, and on a macro scale, to evolve new species.

2) A disadvantage is that most random mutations are harmful, and many are fatal. Thus, only species with a large number of offspring can afford a high mutation rate, as they can afford to write-off many defective individuals.

Another factor is the lifespan of the individuals of the species (or technically, the age at which they are fertile). The shorter this period, the more variation will result from a given mutation rate. Thus, short-lived species don't need as high of a mutation rate as long-lived species would, in order to achieve the same overall variation per time period. The conclusion: if you are a short-lived species that produces many offspring but has difficulty finding a mate, asexual reproduction makes senses. If you are a long-lived species that produces few offspring and finds no difficulty finding a mate, then sex makes senses. I do agree, however, with the previous poster that being flexible would seem to be the best strategy of all. There must be some hidden disadvantages to this system, though, or I'd expect it to be nearly universal. It does seem quite common in plants, however. StuRat (talk) 14:44, 12 April 2008 (UTC)

One obvious disadvantage to sexual selection is that efforts must be put in to make a gene carrier--aka organism--sexually attractive. Consider the peacock's tail. One can argue that it fosters health in the long run, but it is a trade-off nonetheless. It's been stated here too that some species find it difficult to find mates, which is a related problem. Imagine Reason (talk) 00:01, 13 April 2008 (UTC)

See Daphnia#Reproduction which exhibits flexibility in reproduction. I think it is a good strategy for their species.--Lenticel ^(talk) 16:42, 12 April 2008 (UTC)

Giant Fish

http://www.npr.org/templates/story/story.php?storyId=7692201 Can someone please tell me whether this fish is a marlin or something else? The description is vague and not very helpful. Any related articles would be greatly appreciated. Thank you. 99.226.26.154 (talk) 02:36, 12 April 2008 (UTC)

see roundscale spearfish Dismas|^(talk) 03:02, 12 April 2008 (UTC)

Thank you —Preceding unsigned comment added by 99.226.39.245 (talk) 18:16, 12 April 2008 (UTC)

Sodium Hydroxide page safety

I was reading the safety section of the sodium hydroxide article and noticed that it said wash any areas that come into contact with the chemical with water, I was almost positive that it should be vinegar but I dont want to change the page if I am wrong so I was wondering if anyone else knew the answer to that, I just dont want anyone getting injured due to a small discrepancy. (sorry if this is the wrong place to post this question) http://en.wikipedia.org/wiki/Sodium_hydroxide#Safety Pascha mit futbol (talk) 03:33, 12 April 2008 (UTC)

If your skin comes into contact with it, water should be used immediately to throughly rinse away anything residual. However, if there is a large spill, the sodium hydroxide should be neutralized with a weak acid (e.g acetic acid). Try this link [4]. Wisdom89 _{(T / ^C)} 03:58, 12 April 2008 (UTC)

If you should happen to have an open bottle of vinegar in one hand while spilling sodium hydroxide on the other, by all means rinse with the vinegar first. However, in most situations water is more likely to be available quickly and in sufficient quantities than vinegar. In cases of skin contact with sodium hydroxide, or any other caustic substance, it is generally more important that it be washed off as quickly and as thoroughly as possible than exactly what one should wash it off with. In most cases running water will be the best option, but if that's not immediately available, use whatever you have. —Ilmari Karonen (talk) 06:54, 12 April 2008 (UTC)

Here is a much more common situation. You are in the kitchen and you burn your finger by touching a hot pan. What to do? You can open the freezer and plunge you hand into a pile of ice, or go to the sink and run cold water on your finger. The second choice is better. Copious amounts of water will remove heat from the burned finger more quickly than the ice will, because the water is in better contact with the burned area. The excess heat in the burned area continues to do damage until it is removed: every second counts. In theory, ice (being colder) will remove heat more quickly. In practice, running water will always win: quicker to get to and much better fit to the affected surface. This is exactly equivalent to the chemical problem. Every second that the chemical is touching the skin, the skin is being damaged. Running water cannot neutralize the chemical, but it will begin removing the chemical instantly, while going to the cupboard, opening a bottle of vinegar, and then pouring it will take many seconds. In addition, your habits are such that you have no problem using copious amounts of water, but you are unlikely to be willing to dump the entire bottle of vinegar onto your finger. -Arch dude (talk) 00:17, 13 April 2008 (UTC)

name for dysfunction

I am researching the ability of people from separate culture groups to comprehend differences in meaning, usage, inflection and other subtleties of language. In all of the languages of Western Civilization one would not expect to find misunderstanding in the difference between the words "view" and "pay." Members of some non-Western cultures, however, appear to be unable to comprehend the difference. For instance, most utility companies have web sites where customers can login to view their bill from the home page. Any web page developer would naturally be expected to entitle a link for the customer "view their bill" link as a "View your bill" link. Members of some non-Western cultures, however, are invariably unable to comprehend the difference between a "View your bill" and a "Pay your bill" title. The only similar situation I have encountered is with the same non-Western cultural group who are likewise unable to make or use the distinction between the words "ask" and "axe." Although manifested in language is there a scientific, psychological or medical term for this dysfunction? 71.100.160.37 (talk) 03:52, 12 April 2008 (UTC)

First, if a trait is shared among entire cultures, it would probably not be considered a "dysfunction" by modern, educated researchers. Second, I doubt your claim that large numbers of people cannot understand the difference between the meanings of the words "view" and "pay". Do you have a reference? Third, while some people do pronounce the word "ask" the way most English speakers pronounce the word "axe", do you have evidence that these people cannot hear the difference between the two pronunciations? Like many people from my own region of the USA, I pronounce "pen" the way many English speakers pronounce the word "pin", but that doesn't mean I can't hear the difference. --Allen (talk) 05:32, 12 April 2008 (UTC)

The difference in sound for the Homonyms "pin" and "pen" is that "pin" is spoken somewhat more crisply than "pen" is spoken. The difference in sound between "ask" and "axe" is far more different. Its the kind of error one might make when learning a new name so if never corrected then at some point it may be impossible to correct. I can't think of an example this far past my bedtime but many languages seem to have syllables that are pronounced differently in the native language such that "ask" may be a word that was impossible to pronounce correctly, although the culture I am referring to is like a stem cell in that native pronunciation should not be a problem. Large numbers in this case simply means of those persons hired to write copy or perform other literary tasks. A high percent of persons hired from the culture had a similar misunderstanding regarding phases like "large number" in that they had only learned one sense. In this case the phrase "large number" meant eight out of ten persons hired rather than a statistically significant number like fifteen hundred. Although the "trait," as you call it, is more prevalent within a certain subgroup of the culture perhaps there is a correlation with those who have technical training and lack English skills. Until we became aware that there was a problem we did not screen for English skills and unfortunately for some if this is not a known dysfunction then disability compensation would not be an option. 71.100.160.37 (talk) 07:37, 12 April 2008 (UTC)

Are you sure about the 'ask'/'axe' thing? [5] [6]? In any case, I'm not sure if you answered the question from Allen, are you sure that the people are not unable to make the distinction as oppose to simply a pronounciation difference while still being able to make the distinction? BTW, who defines what's the correct pronunciation of a word? Nil Einne (talk) 19:41, 12 April 2008 (UTC)

I suppose that following the American Revolution Americans began to identify with specific pronunciations, for instance skedjewl versus shedule, the later being a pronunciation associated with the enemy or former enemy. Same word, different pronunciation atypical of national affiliation. Both references above BTW are excellent and by the same token (BTST?) may only indicate affiliation with one region or another versus affiliation with a particular culture, although in all but one case I have never heard "axe" pronunciation spoken outside of the particular culture due possibly to the potential confusion with the noun "axe." The particular culture that uses "axe" pronunciation seems oblivious to the fact that the noun and the verb can be confused resulting in unintentional meaning. For instance, was he fired, (he got axed) or was he consulted (he got asked). Hence the assumed illiteracy of the speaker and of his region or cultural. 71.100.160.37 (talk) 10:22, 13 April 2008 (UTC)

You seem to be repeatedly assuming that this unnamed culture is unable to do various things without evidence to back up your assumptions. They "seem oblivious?" To "the fact that the noun and the verb can be confused?" According to Stanford linguist John Baugh, "[aks] never occurs in linguistic domains where it is truly ambiguous with 'ax.'" (Beyond Ebonics, page 94) The Wikipedia reference desk is really for asking questions and answering them, citing reliable sources. I think your question has been answered: As far as anyone here knows (or, at least in my case, can possibly imagine) there is no scientific term for the "dysfunction" you posit. A little digression and speculation here is usually tolerated, but I think it would be nice if you backed up with references any more negative claims about other cultures, and nicer still if you restricted such claims to direct answers to others' questions. --Allen (talk) 17:13, 13 April 2008 (UTC)

You seem to forget that the Wikipedia reference desk does not work in real time, forcing the OP to return again and again in hope of finally getting an answer. In the meantime discussions break out. Start providing realtime answers and your desire for no interaction might have merit. The kind of references and evidence you demand are only necessary if one is trying to make a point while my goal is merely to determine if the failure of one culture to fully comply with the requirements of another culture can be defined as a dysfunction so that members of that culture might seek disability compensation rather than blaming the other culture for rejecting them on some false and projected basis like cultural prejudice. But then I realize if you belong to that culture, have been so rejected without opportunity for disability compensation, that your bitterness is in fact evidence that I'm wasting my time. 71.100.160.37 (talk) 05:27, 15 April 2008 (UTC) —Preceding unsigned comment added by 71.100.171.178 (talk)

You seem to be confusing many different issues:

1) Some languages don't distinguish certain sounds. For example, Orientals tend not to distinguish between L and R.

2) Some words sound alike in some accents of the same language, but not other accents.

3) Some concepts only exist in certain cultures and are difficult to understand in others. Inanimate objects having a gender is one example. StuRat (talk) 03:11, 13 April 2008 (UTC)

Good points StuRat. No doubt if you did a study of misunderstandings resulting from such differences you might come to the conclusion that for particular groups made up of mixed cultures that the language they use needs to be standardized according to specific rules which some members may be unable to follow resulting in their necessary exclusion from the group. "I told you to ask the prisoner, not to axe him!" 71.100.160.37 (talk) 10:32, 13 April 2008 (UTC)

Muscle stiffness, weakness and soreness

I have muscle weakness, stiffness and soreness in my back and legs. What could be causing it? I have been through several physicians and have only medical bills and debt to show for it. —Preceding unsigned comment added by 63.237.114.10 (talk) 07:43, 12 April 2008 (UTC)

See our Wikipedia:Medical disclaimer - we cannot offer any form of medical or legal advice that would otherwise be provided by a professional. You need to depend on your physicians. Wisdom89 _{(T / ^C)} 07:58, 12 April 2008 (UTC)

Indeed, if you've only been seeing GPs, you may want to see a specialist of some sort although I'm not really sure what sort. Nil Einne (talk) 13:34, 12 April 2008 (UTC)

specific gravity

A body weighs 3 kg in air. If it is submerged in a liquid, it weighs 2.5 kg. What is the specific gravity of the liquid.Jalaludeen (talk) 13:59, 12 April 2008 (UTC)

I don't think there's enough info. We'd need to know the density of the object, or it's volume, since we could get density from it's mass and volume. Consider submerging two 3 kg objects in water. If you submerged 3 kg of styrofoam it would actually have a negative weight in water, or in other words, it would float. On the other hand, 3 kg of lead would still weigh close to 3 kg, since it's density is so much higher. StuRat (talk) 14:07, 12 April 2008 (UTC)

"3 kg of styrofoam...have a negative weight...3 kg of lead...still weigh close to 3 kg"

That means that knowing the initial weight and final weight, it's possible to calculate density. Buoyancy from water applies an upward force of 1 g per g/cm^3 of the submerged object, since water's density is 1 cm^3. Because the 3 kg body's weight became 2.5 kg, a reduction of 500 grams, that must mean the volume is...the rest is left as an exercise to the OP. :) (If this isn't a homework question, sorry for my misunderstanding, but the final answer should be easy to calculate.) --Bowlhover (talk) 22:29, 12 April 2008 (UTC)

The OP didn't say the liquid was water. The question was to find the SG of the liquid, so the liquid is the unknown. There still is not enough information. Sure, 500g of liquid has been displaced, but the only way to know what volume that occupied is from the density of the supermarket trolley or whatever it was that was thrown into the local swamp. By the way, is there any liquid that styrofoam will sink in? SpinningSpark 23:04, 12 April 2008 (UTC)

Sorry. I should have read the question more caref...well, I should have the question. --Bowlhover (talk) 02:34, 13 April 2008 (UTC)

I speculate that Styrofoam would sink in liquid Helium, but we would very rapidly get into obscure arguments about the definition of Styrofoam at 4.22K, because Styrofoam is a composite material one of whose components is air. If you can believe Tom Clancey, there is a tradition in the deep-diving community of presenting a new passenger of a deep-diving submersible with a Styrofoam cup that had been placed in the external sample basket prior to the deep dive. After the deep dive, the cup is dramatically smaller because all of the air was forced out of the interstices during the dive. An equivalent phenomenon would occur as the air froze when the Styrofoam was immersed in liquid helium. -Arch dude (talk) 23:57, 12 April 2008 (UTC)

I've seen one of those crushed cups (divers should concentrate more on what they are doing in such a dangerous profession instead of fooling around) but I am not convinced liquid helium would have the same effect. The cup under water has the great pressure of the depth to crush it after the air has been forced out. In fact, the air is coming out because it is being crushed rather than the cup is crushed because the air has come out. In liquid helium, there is no change in pressure (unless you are postulating a VERY large tank). It would be more a case of the air dripping out. The vacated space would be replaced by helium and the cup structure would maintain integrity. SpinningSpark 22:18, 13 April 2008 (UTC)

Having now looked up the density of styrofoam, I also dispute that it would sink in the first place. The densities I found quoted for commercial styrofoam ranged from 35 to 45 kg/m³. According to our article liquid helium has a density of 125 kg/m³. SpinningSpark 22:35, 13 April 2008 (UTC)

The helium page states (and cites) that styrofoam floats on normal liquid helium. DMacks (talk) 05:22, 14 April 2008 (UTC)

Reasoning validity of interesting excerpt...

In my hot-air balloon bunting adventures around the internet in eighty aeons, I recently came across the following passage, and wondered what sense to make of it:

Today, physics is explained in terms of group symmetry, for example U(1) for electromagnetism, SU(2) for spin in three dimensions or electroweak force field, and so on. On the other hand all symmetries must merge at least at the so called Planck's elementary scale, near 10-33 cm. from quantum mechanics, the smaller the scale the larger the energy. So, the planck's unit is something as 10^29 times (ten billions of billions of billions) more energetic than the simple photon of visible light.

From modern physics experiments, it seems the electroweak force field must fuse with nuclear force at a scale near 10 000 Planck's units. A light radiated at that level would not see an Universe with an infinite number of directions, for it the world would be a sphere made from small Planck's unit surfaces. The surface of a sphere is given by the formula: 4 x Pi x R^2, or 1 256 000 000 for R = 10 000. The biggest possible energy for a photon gives it a view of the Universe with something as one billion possible directions.

Quantum mechanics produces a strange phenomena: the so called state superposition: A photon radiated at the elementary scale will goes in one billion directions at the same time! It will get to one billion different places after one crossing time, the time it take to travel at light speed a distance equal to R ( 10 000 Planck's units). Such a quantum process can works with virtual particles using no net energy at large scale. That is to say, it will take place continuously everywhere in each space element 10^-29 cm long and on a time scale near 10^-39 second.

I would verily appreciate if the veritable brainsponge thinkclouds that inhabit this vast elysia of edification could grant me the boon of explaining, with specific reference to points in the passage, whether this line of inference would be well-recieved in the court of physics comprehension, and if not, at which syllogistic leap the jester might fear for his position. This I entreat of you, my good fellows, in the assurance that I will not soon forget my benefactors, when after many leagues and perils, I complete my journey and return with the trove of ages. Most lostentatiously, Ernst Valiance de Fargowellsenstein, esq. —Preceding unsigned comment added by 85.194.245.82 (talk) 16:23, 12 April 2008 (UTC)

You could start by taking a look at our article Symmetry in physics. For a more mathematical point of view (but still readable) there is Symmetry group. For electromagnetism and the U(1) and U(2) groups in particular, take a look at Gauge theory. For a deeper mathematical understanding there is Special unitary group which will tell you about SU(3), needed for quarks and the strong nuclear force and if you're really brave you could leap into Standard Model (mathematical formulation) which will tell you about SU(3)xSU(2)xU(1) - basically the theory-of-everything-except-gravity.

Many in science are coming to believe that symmetry is what lies behind it all and to make further progress in our understanding we should be looking for deeper and simpler symmetries. Oh, and your questions on quantum theory, look at Quantum mechanics. SpinningSpark 16:41, 12 April 2008 (UTC)

One was rather hoping that the trouble might actually be taken to read and attempt to explain the passage, as the object of my mission is the assessment of its veracity, rather than a expenditure of time perusing the background of the subjects alluded to, which fascinating as they might be, would be of no immediate assistance in determining the credibility of the syllogistic in question, and would detract immeasurably from my various aviational adventures and epic travails. Which is to say, dear friends: does anybody else care to assist? E. V. de F., esq. —Preceding unsigned comment added by 85.194.245.82 (talk) 00:48, 13 April 2008 (UTC)

Herewith is my humble assessment of the veracity of your quoted passge.

The first paragraph is a summary of standard physics. In particular, the Planck energy is about 2x10⁹ Joules, which is about 10²⁸ times as energetic as a typical light photon.

The second and third paragraphs are a veritable pile of unicorn droppings, especially the parts about light "seeing the universe" in a number of directions and photons going in "one billion directions at the same time". It might be a (not very good) attempt to describe quantum foam. However, in the absence of a consistent theory of quantum gravity, any current statement about physics at the Planck length scale will be mostly speculation. Gandalf61 (talk) 10:03, 13 April 2008 (UTC)

Good and wisened mage, of long and venerable lineage, I thank you for your gracious and esteemed counsel. My travelling companion, though feathered and vulgar-of-tongue as any not-long-since buccaneer's shoulder-mate he may be, did study for some time under a greatly learned and erudite master the ars physica, and his reckoning, at least while sober, I trust above all unplumaged bipeds. He proposes that the intended sense of "direction of seeing the universe" might refer to the maxima on the spherical surface of the light-cone extending from a photon emmision event after a propagation time of 10,000 planck units (equivalently, radius of 10,000 planck lengths), the number of which indeed grows as the square of radius. The reference to "all direction at once", my squalking sea-faring sidekick suggests, is equivalent to sum-over-histories formulation of QED, in which all possible paths within a light-cone contibute to the quantum amplitude of the EM transmission. What say you, sir, to these comments? E. V. de F, esq. —Preceding unsigned comment added by 85.194.245.82 (talk) 20:06, 13 April 2008 (UTC)

Is it mere coincidence that, prior to the addition of this non-sequitous comment, the words following that parroty were, "Bird Poop?" ;-) --Prestidigitator (talk) 21:41, 13 April 2008 (UTC)

A most serendipitous synchronicity of jungian justapoxition, one can only surmise. E. V. de F., esq. —Preceding unsigned comment added by 153.1.253.5 (talk) 13:01, 14 April 2008 (UTC)

Bird Poop

<moved from miscellaneous desk>
There is bird poop on my sliding glass door. Who knows how it got there... Anyway the question I have is; Why is bird poop white? 71.142.208.226 (talk) 21:28, 12 April 2008 (UTC)

Because white is a neutral color and because the poo can match the fluffy clouds in the sky. For all I'm concerned clouds are bird poo.

Always

Cardinal Raven

Cardinal Raven (talk) 22:00, 12 April 2008 (UTC)Cardinal Raven

That possibly can't be true. 71.142.208.226 (talk) 22:17, 12 April 2008 (UTC)

Birds do not urinate, instead they secrete uric acid into their droppings which is white and makes up the bulk of it. Nanonic (talk) 22:36, 12 April 2008 (UTC)

Birds don't just drop it, they eject it at an angle, so if one happens to be flying past your window, it can score a hit. Graeme Bartlett (talk) 12:07, 13 April 2008 (UTC)

Thanks for explaining why when I clean my car windows, I do not think of clouds (but will try to in future). Julia Rossi (talk) 02:35, 14 April 2008 (UTC)

Star and Sun

Why do we say the Earth rotates around its sun, but if it was another planet they say Plaid(my example planet I made up) rotates around its star every 8.3 minutes? Why is it Sun for Earth, but star for other planets like Plaid(my made up planet)?

Thank You

Always

Cardinal Raven

Cardinal Raven (talk) 23:21, 12 April 2008 (UTC)Cardinal Raven

(edit conflict)Hi. Well, the reason why our sun is called "Sun" is because, well, it's our sun. Other stars are stars because they're not our sun. If we lived on Plaid, though, the star it orbits might be called "Sun", were we to speak English. Some stars have names, though. Also, if we spoke English and lived on any other planet orbiting the sun, we'd still call it "Sun", although it may be brighter or dimmer than on Earth. However, since Plaid (your example) rotates around a star other than our sun, we say it rotates around a star, but most stars have either a name or some kind of formal designation. Hope this helps. Thanks. ~AH1^(TCU) 23:32, 12 April 2008 (UTC)

But, why is that so? Our sun is still a star. And the stars are still suns. What made it that way?

Always

Cardinal Raven

Cardinal Raven (talk) 23:45, 12 April 2008 (UTC)Cardinal Raven

My guess is that the names of the sun and stars were made before people knew they were the same. —Preceding unsigned comment added by 59.100.167.250 (talk) 00:13, 13 April 2008 (UTC)

That the Sun is a star is not at all obvious. Though a smattering of people thought so early on (e.g. Anaxagoras), it was still a heretical idea well until after the main body of work of the scientific revolution. As for why we call our sun The Sun, well, it has historical antecedents. To call it by a more formal name (e.g. Sol, as some sci fi writers often do) seems silly when we've been calling it The Sun for so long. --Captain Ref Desk (talk) 00:33, 13 April 2008 (UTC)

This is a language question, not a science question. "The Sun", capitalized, is the English name of a particular star. The star's name in latin is "Sol". The (non-capitalized) word "sun" designates the primary of a star system. So: the sun of Earth is Sun, or the sun of Terra is Sol. The sun of Plaid is Fomalhaut. In general, you can replace the (non-capitalized) word "sun" with "primary." The (capitalized) word "Sun" is the (english) name of a particular star whose third planet is named (in english) "Earth." The name of Earth's primary is "Sun." Earth's sun is named "Sun." Earth's astronomers have formal names for most of the 6000 or so visible stars, but the millions of other stars have other designations in several systems. Presumably, the inhabitants of Plaid will name their sun. Perhaps they will name it "Tartan." . If the primary of Plaid is not visible from Earth, the government of Earth will probably acknowledge the new name for the star. If the inhabitants of Earth already have a name for that particular star, there is likely to be a truly silly debate over the correct name for the star. -Arch dude (talk) 00:58, 13 April 2008 (UTC)

Btw, Earth revolves around the Sun, each complete trip marked as a year. Earth rotates around its axis, creating days. Imagine Reason (talk) 01:18, 13 April 2008 (UTC)

URGENT

Is it safe to??? —Preceding unsigned comment added by 79.122.53.15 (talk) 23:29, 12 April 2008 (UTC)

Hi. Could you please specify if what is safe to? We cannot answer your question if you do not tell us your question. Also we can not give you professional advice. Thanks. ~AH1^(TCU) 23:35, 12 April 2008 (UTC)

NO! It is NOT safe to ?? Stop now. Exit the premises. Call the fire department. Call the police. Duck and cover. Move away from the keyboard. -Arch dude (talk) 23:39, 12 April 2008 (UTC)

Thank you!!!! Your quick advice helped me to avoid certain doom :) —Preceding unsigned comment added by 79.122.53.15 (talk) 01:58, 13 April 2008 (UTC)

Is it safe to question a question? Questioning this Question will cause the author to harm you in all possible ways. Questioning about a question will incite personal descrimination from the questioner. Questioning why questions exist brings up an issue nobody questions but the questioners of all questions. And why do you question so much, anyhow? --99.237.101.48 (talk) 23:28, 13 April 2008 (UTC)

It is not safe to live. You will die doing this. Mac Davis (talk) 06:54, 14 April 2008 (UTC)

If you have to ask, it isn't. Another clue would be the urge to shout "Hey, watch this!" or "Here, hold my beer for a sec..." just before you do it.

Atlant (talk) 12:03, 14 April 2008 (UTC)

Protein homology dataset

Where can I get a dataset of protein homology? I searched the Internet and found <http://mips.gsf.de/>, but I am unable to locate any dataset there. Note that I have a Computer Science background, and I have not studied any Biology since joining University. --Masatran (talk) 23:31, 12 April 2008 (UTC)

Since no one's bitten yet: I don't know if it helps, but the science forum of folding@home might be able to help. Proteins are right up their alley. --Lisa4edit (talk) 14:32, 13 April 2008 (UTC)

This any useful? http://webclu.bio.wzw.tum.de/simap/web/simap/fulltextsearchresult --Lisa4edit (talk) 15:19, 13 April 2008 (UTC)

What are you looking for in a protein homology dataset? (To what purpose are you going to employ it?) The standard repositories of Entrez and Expasy have sequences of most all of the proteins know to science, with some cross referencing for homologous proteins. If you have particular proteins you hope to find homologs to, you can always try BLAST type searches. If you are looking for structural similarity, there is always Scop or CATH or FSSP. One issue you're going to run into is the definition of homology - strictly speaking, homology is an evolutionary relationship. Unfortunately, we can only infer evolutionary relationships through sequence and structural similarity. How much experimental evidence of evolutionary relationship do you need? Also, how closely related do two proteins need to be before you call them homologs? There are instances of similar sequences giving different folds, and different sequences giving similar folds. I can't think of specifics at the moment, but I believe that there are structurally and functionally similar proteins which are hypothesized to have arose from separate evolutionary paths. -- 128.104.112.85 (talk) 18:55, 13 April 2008 (UTC)

The mips datasets are still online. Go here: http://mips.gsf.de/projects/funcat, ftp://ftpmips.gsf.de/catalogue/, ftp://ftpmips.gsf.de/catalogue/annotation_data/ etc. As for other databases, I would recommend KEGG first and foremost. --Rajah (talk) 06:05, 14 April 2008 (UTC)

April 13

Charge

if there is say, a proton and electron, not in contact with each other, how does the proton know the electron is negatively charged, and move towards it and vice versa? Philip Woods (talk) 12:07, 13 April 2008 (UTC)

Well they don't "know" that the other one is the opposite charge really, its just that they get pulled towards it each other.--Phoenix-wiki 12:24, 13 April 2008 (UTC)

You've hit on one of the unknowns of the universe, how forces act at a distance. Your same question can be extended to all the fundamental forces, such as gravity: "How exactly does the Earth 'know' the Sun is there to orbit around it ?" One attempt to explain how such forces work at a distance is gauge bosons. As I understand it, however, an infinite number of massless particles would need to constantly emit from every subatomic particle which exerts a force in order for this to work. The gauge boson for gravity is the graviton and for electromagnetism it's the photon. The graviton is especially problematic, leading to new conjecture in string theory to try to explain how gravity works at a distance. StuRat (talk) 13:01, 13 April 2008 (UTC)

The force between an electron and a proton is an example of the Coulomb force. This force is communicated by means of virtual photons. Since these particles cannot be directly observed, you might not find this explanation very satisfying, but it's the best there is. --Heron (talk) 13:46, 13 April 2008 (UTC)

StuRat just gave an epic answer. Mac Davis (talk) 06:53, 14 April 2008 (UTC)

Not being able to directly observe something isn't the issue, I believe in many things that I can't personally see. The question is, can they be experimentally verified ? StuRat (talk) 15:29, 13 April 2008 (UTC)

their electric fields? Em3ryguy (talk) 16:11, 13 April 2008 (UTC)

The Lamb shift and the Casimir effect are experimental verifications of the existence of virtual photons - see this Scientific American article. Gandalf61 (talk) 17:47, 13 April 2008 (UTC)

Ok, but how about gravitons ? StuRat (talk) 18:11, 14 April 2008 (UTC)

I assume that the idea of VIRTUAL photons is just another way of thinking about the same underlying phenomenon. Sort of like lines of force. They dont really exist but they help one to visualize whats going on. but i am not an expert so i can always be wrong. Em3ryguy (talk) 20:07, 13 April 2008 (UTC)

The word "virtual" in virtual photons causes some confusion. These are real photons - or at least, they have as much "reality" as any other unobserved particle in quantum mechanics - they are only "virtual" in the sense that they only exist for a short period of time. But if virtual photons cause you a headache, you can use the alternative dual concept of zero-point energy. Either way, these are inherently quantum concepts - they have no equivalent in classical physics. Gandalf61 (talk) 09:14, 14 April 2008 (UTC)

Yes, that does seem to be a misuse of the word "vitrual". Something like the "random" in "random access memory" ("which byte should I return to the user, let me just flip a coin to find out") or the "auto" in "autopsy" (cutting yourself open after death ?). StuRat (talk) 18:07, 14 April 2008 (UTC)

Biggest bang for the buck in health care

I heard the US pays something like 6th most per capita on health care but is something like 27th in effectiveness of their health care system. (Those numbers may be off a bit.) My question is, which countries have a highly effective health care system despite paying little for it ? StuRat (talk) 15:03, 13 April 2008 (UTC)

According to our article, the US spends the most on health per capita. Anyway, there are no doubt several such countries, but Cuba is the most obvious one. Algebraist 16:41, 13 April 2008 (UTC)

Somehow, paying doctors the equivalent of $US 15-20 per month feels like cheating though. I'm sure our healthcare system would also be much more affordable if doctors worked for (essentially) free. Dragons flight (talk) 17:51, 13 April 2008 (UTC)

It becomes difficult to answer this question when you say "effective". For example, if you don't spend any money at all to treat things like AIDS and diabetes, then those people will die quickly. You get them off your stats and have a healthier population. You can stretch it even further. Someone has a car accident and is bleeding internally - just let them die. Then, you won't have bad stats for having a person in need of a lot of health care later. You can also refuse to treat the mentally ill. You save a lot of money and nobody really has any idea how many mentally are not being treated. You can rank really high on infant morality by aborting any babies that have the slightest health risks. It is cheap and only healthy low-risk pregnancies make it on your stat sheet. Overall, you have to consider how many chronically ill patients get health care in any two systems you compare just as well as comparing the healthy people. Most arguments for social medicine only consider the healthy patients and ignore the chronically ill and the preventable death rate. -- kainaw™ 19:56, 13 April 2008 (UTC)

Accoding to the World Health Organisation the US government spends more money on health care than most, supposedly "socialist", European governments - Healthcare spending (government alone!) per person per year in the USA is $2,700. Compare this to - France:$2,400 Germany: $2,400 UK: $2,200 Sweden:$2,400 Italy:$1,800. Yet somehow the USA manages to leave 1/5 of its population uninsured, and many more underinsured, while Europeans enjoy a decent quality of state-funded universal health care, free at the point of use (no extra co-insurance, co-payments and deductibles needed). One wonders where all the money in the US goes... On the other hand, average cancer survival rates are higher in the US than in Europe. Medical research is also much stronger in the US - if you want to get the newest form of state-of-the-art treatment (and can afford it), you often have to go to America.

I guess it depends what you mean by "effective". The UK has a highly cheap and effective health care system for treating common ailments, the US has an expensive, but effective system for treating serious diseases. Someone in the US with cancer might be forced to sell their house and go bankrupt, but at least they are more likely survive in the end. Cambrasa 00:17, 14 April 2008 (UTC)

OK, to get around the vagueness of "health care effectiveness", let's use "life expectancy", instead. While perhaps not ideal, that is a metric that should be available for most countries. StuRat (talk) 18:01, 14 April 2008 (UTC)

The problem there is, life expectancy depends on several factors, not just health care. For example, Singapore and Japan have some of the highest life expectancy rates in the world, but I don't think these are usually solely attributed to their health care system (I'm not saying they're bad) but other factors like diet as well. Nil Einne (talk) 21:50, 14 April 2008 (UTC)

I realize it's not perfect, but it's not bad. In many ways, the diet, sanitation, etc., of a country can be considered to be extensions of the health care system. I've even seen attempts to treat violence as a contagion. (One gang member kills someone in another gang, then that gang kills two in the first gang, and so it spreads.) StuRat (talk) 02:16, 15 April 2008 (UTC)

Shock

If you hold on to both terminals of a car battery will you get a shock? —Preceding unsigned comment added by 70.56.125.7 (talk) 16:03, 13 April 2008 (UTC)

Yes, I will.--Shantavira|^{feed me} 17:15, 13 April 2008 (UTC)

In a circuitous sort of way, I would have to conclude that it is very likely that you would. Here's a related question - in the movies and TV, people in that situation are unable to disengage themselves. Is this because of the effect of electricity on the muscles, or is that just a Hollywood myth? Clarityfiend (talk) 17:32, 13 April 2008 (UTC)

If they have become married it would be shocking to disengage. --Cookatoo.ergo.ZooM (talk) 17:47, 13 April 2008 (UTC)

You will not get a shock. It's only 12 volts. Hollywood also thinks that high-voltage cables writhe like snakes when lying on the ground, and that all vehicles explode into a fireball in every collision. --Heron (talk) 17:46, 13 April 2008 (UTC)

The 12-14volt battery in a car won't be able to shock you, no. You might feel something if you have wet hands, but otherwise there isn't enough voltage to get past your skin. If, however, you stuck electrodes into your bloodstream and connected them to a car battery (even a little 9volt, or so I've heard), then you are unlikely to live to tell about it. As for the second question, electrical current is known to cause muscle contractions. Since the flexor muscles (in general and especially in the hands) are stronger than the extensor muscles, the net effect of gross electrical stimulation is flexion. Therefore it is possible that your electrified hand may grasp the conducting material and be unable to let go. Of course much of the rest of your body will also be contorting, and this is likely to pull you away from any fixed object, but flexible conductors, such as wires, may come with you if gripped firmly. This is why electricians are trained to touch possibly electrified equipment with the back of their hands first. Tuckerekcut (talk) 17:59, 13 April 2008 (UTC)

High voltage wires which fall to the ground in fact can jump around. Sometimes they just lie there all innocent, but ready to kill anyone who touches them or the metal fence they are lying on. Other times the smoke. Other times they make a popping noise as the end pops up in the air repeatedly. Edison (talk) 21:56, 13 April 2008 (UTC)

Okay, time for the [[Citation needed]] thing. Two statements have been made which I'm having trouble with:

1. "If you stuck electrodes into your bloodstream and connected them to a car battery, then you are unlikely to live to tell about it"
2. "electricians are trained to touch possibly electrified equipment with the back of their hands"

I suppose #1 might be true, but I'm inclined to doubt it. And I'm quite sure #2 is false: the way you touch a possibly live object safely is not to touch it at all. You use a neon test lamp or other voltage tester, obviously.

Anybody got any definitive references for either of these? If not, I call bovine byproduct.

In answer to the original question, the other posters are right: simply touching the terminals of a car battery won't hurt you a bit. 12 volts just isn't enough to shock you. (And don't be misled by the car battery's huge current-supplying capability: that has nothing to do with the electric shock question.) —Steve Summit (talk) 00:01, 14 April 2008 (UTC)

Well, 12 V is certainly "enough to shock you", however, touching the terminals with your hands might not be enough to "hurt you a bit". Was I the only kid that had been tricked into (and then tricked someone else into) licking a 9 V battery? See also our electric shock article. I remember reading somewhere that certain types of shocks (maybe AC vs DC, or certain frequencies, or certain voltages, or...) caused reflexive release or recoiling from the source whereas others caused inability to release, but can't find it at the moment. DMacks (talk) 05:17, 14 April 2008 (UTC)

Tricked, no. But I have frequently tested 9V batteries with my tongue. I have been told it's a bad idea.

Also, this site discusses electric shocks making your muscles contract and forcing you to hold onto a live wire. AlmostReadytoFly (talk) 10:57, 14 April 2008 (UTC)

If you kept a 9V battery on your tongue continuously, you might electroplate some metal onto your tongue and that probably wouldn't be good for you. But aside from the "startle" factor, I can't see where the occasional casual touch of a 9V battery to your tongue could hurt you and I, like you, do it routinely to assess the go/no go state of a 9V battery. Over the years, my tongue has gotten pretty well calibrated (say, +/- 1 volt) but my wife still gets a laugh when she sees me doing it.

Atlant (talk) 11:57, 14 April 2008 (UTC)

I agree that professional electricians are not trained to test a possibly live wire by nicking it with the back of their finger, but I have personally seen a number of them doing so, and I myself do it after I've done the other tests, just as a final head check. I figure if I'm about to touch the wire anyway, why not do it in the safest way I can? --Sean 12:12, 14 April 2008 (UTC)

No, but if the battery is an old, unsealed battery in really poor condition, you might get a chemical burn from the deposits that used to form on the battery's terminal studs. This seems to be much less of a problem with modern mostly-sealed batteries.

Atlant (talk) 11:53, 14 April 2008 (UTC)

I have personal experience with not being able to let go of an electrified object. When I was 5 we had a farm nearby and I went "to see the horsies". I grabbed onto the metal fence with both hands, only to find out it was electrified. I couldn't let go and couldn't talk. Fortunately, it was the modern type with the safety feature which cycles on and off, and I was able to let go once it cycled off. The older type, without that feature, would probably have killed me. StuRat (talk) 17:55, 14 April 2008 (UTC)

Stu, I have to disagree here, you felt a god-almighty, I'm-dying-now jolt that taught you a good lesson, but the lesson ended real soon. Electric fences are high-voltage, low-current devices designed to teach lessons with pulses. I'd like to see your reference to the older type that would have killed you, presumably it would kill a calf also - which farmers were in the habit of killing their animals for touching the fence? Wouldn't they just use a rifle? It sure does feel like you're dying, but the 12-volts is at the fence battery, you're feeling the coil pulse, many more volts than 12, and it's just a quick reminder. Bet you never touched it again :) Franamax (talk) 22:16, 14 April 2008 (UTC)

The muscle contraction response only forces you to grab onto the item if you have hands capable of grasping. It's pretty darned difficult to grasp anything with a hoof, so the animals would be perfectly safe. If I, on the other hand, could not let go, I'd have been there for a very long time, and it seems like very little voltage/amperage is needed to interfere with the heart's electrical signals. I also don't see how I could breathe like that. StuRat (talk) 02:03, 15 April 2008 (UTC)

So how long was it, that the juice was on, that you couldn't let go and couldn't breathe, before the "modern safety feature" deenergized the fence and saved you?

Agricultural electric fences that I'm familiar with (including the one *I* foolishly touched when I was 5) deliver brief pulses of high voltage, once every second or two. And this has nothing to do with any safety feature; it's inherent in the simple pulse transformer way they work. So I'm puzzled about your experience. —Steve Summit (talk) 02:44, 15 April 2008 (UTC)

It's impossible to say how long it was as "time stopped" for me. I do recall the feeling of helplessness, though, at not being able to do anything to get out of the situation until the pulse ended. StuRat (talk)

In response to the call for citation above: The second statement (that electricians are trained to touch possible live wires first with extensor surfaces) was relayed to me by a friend of mine who is a (certified? i don't know the terminology) journeyman electrician. As mentioned by another poster, this is of course after using other equipment/methods/tag-outs to ensure that the thing in question has been discharged/unnelectrified. I didn't mean to suggest that this was a primary basis of checking, it's more of a last ditch safety measure just in case... The first statement, now that I think about it, really does need more justification. This was something I have heard on three different occasions: the first time it was a high school physics teacher; the second time it was in the context of the Darwin awards, being the cause of death for an unwitting victim; and the third time it was from an instructor teaching an EMT certification course. It was only repetition that led me to consider this a factual possibility, and I happily rescind the statement until such time as I find more convincing support. Tuckerekcut (talk) 18:59, 14 April 2008 (UTC)

This somewhat answers the question [7]. Not technically a reliable source but from my experience, DansData usually gets it right Nil Einne (talk) 19:28, 14 April 2008 (UTC)

Wow! Impressive. Thanks. I guess I'll have to at least partially retract my doubts stated above. —Steve Summit (talk) 22:54, 14 April 2008 (UTC)

What is happening when one thinks one's dreams are reality?

A few times, a couple friends have had the experience of dreaming and being *so* sure it was real later; and I mean for days. Nothing big, except for the time I dreamt a cousin was more badly injured than he was in a fall. (But, that's easily attributed to the stress of the moment - he *was* in the hospital a few days as his spleen healed.) The other times, it's been a scene in a TV show that someone swore was part of the episode and later learned it wasn't in the original airing at all, or something else little. For isntance, in Hogan's Heroes, Col. Hogan delivers a coded message way down in Heidelberg, when that was not actually part of that episode, they convince the friendly sergeant to take it down and are able to get him to go on furlough.

What causes this? Is it just that some dreams are so lucid that we can be convinced they're real? But, why don't all dreams make us think they were real days or weeks later? Certainly only a few have made my firends or me think they were real. And, only the one of mine was caused by a stressful event.

And, no, neither of us has ever taken any drugs or alcohol. Then again it's not uncommon for even neurotypicals to have stress dreams like mine; but I dont' understand the others, how that happens. Somebody or his brother 17:27, 13 April 2008 (UTC)

We cannot give any medical advice on Reference Desk, and that rule kicks in when someone says they have some medical condition or symptom. But we can discuss things like dreams seeming real in general. I would say the many dreams seem real during the dream, but it it rarer for the memory of what was dreamed to be confused with a memory of a real event later, like hours later. Edison (talk) 21:52, 13 April 2008 (UTC)

I thought about that afterword, but I trusted that people would look past what seemed to be a very minor point to the larger question of what process int he brain causes it (which was the question.) So, i deleted it, because I do tend to ramble a bit with things that aren't really as importnat to the discussion

The didactic purposes of a dream would be lost if we were so easily able to brush them off. Vranak (talk) 01:12, 14 April 2008 (UTC)

I have this problem all the time. I mix up real events with dream events. I think of it as confabulation. I haven't identified a reason why this happens, but luckily it hasn't gotten me into any trouble yet :) Also, "lucid" usually means that you understand a dream is only a dream, and is also used to describe the amazing clarity that often accompanies. Mac Davis (talk) 06:52, 14 April 2008 (UTC)

Dangers of carbonated soft drinks

Other than the hazards of sugar, caffeine, and artificial sweeteners, is drinking soda thought to be harmful? For example, is the artificially carbonated water and acidity associated with any health risks?--The Fat Man Who Never Came Back (talk) 17:39, 13 April 2008 (UTC)

Yes. It is known to attack the enamel of the teeth as well. Sweetened sodas are a particularly bad combination, but even carbonated water has some softening effect, if I remember correctly. I'm not aware of any other danger if consumed with reasonable moderation. --Stephan Schulz (talk) 17:45, 13 April 2008 (UTC)

According to Dental caries, tooth enamel is in danger at a pH of 5.5 or below. Carbonic acid gives a table for the pH depending on the partial pressure of CO₂. Judging from this table, carbonated water can be expected to cause dental decay. Icek (talk) 20:12, 14 April 2008 (UTC)

Phosphoric acid is problematic: see Phosphoric acid#Biological effects on bone calcium and kidney health moink (talk) 18:37, 13 April 2008 (UTC)

If I recall correctly, something about the carbonation affects the body's intake of calcium so that long term use may weaken bones. — Ƶ§œš¹ _{[aɪm ˈfɻɛ̃ⁿdˡi]} 02:37, 14 April 2008 (UTC)

The only evidence seems to be epidemiology. Methodologically better experimental studies don't seem to indicate such an effect. One sentence in the artice seems odd: "The study does not examine the effect of phosphoric acid, which binds with magnesium and calcium in the digestive tract to form salts that are not absorbed, but, rather, it studies general phosphorus intake." Whether it's phosphoric acid or phosphate is determined by the pH which is not determined by phosphoric acid in the intestine. And thanks to enzymes like nucleotidases, all bioavailable phosphorus should enter the body as phosphate. Icek (talk) 20:09, 14 April 2008 (UTC)

Consuming anything has health risks—the dose makes the poison. Mac Davis (talk) 06:45, 14 April 2008 (UTC)

Additionally, there has been some evidence that sodium benzoate - a common preservative in soft drinks - may react with ascorbic acid to form toxic benzene. Take a look at benzene in soft drinks. – ClockworkSoul 16:05, 14 April 2008 (UTC)

The sodium is superfluous - benzoate, ascorbate and transition metal ions will do it. Icek (talk) 02:21, 15 April 2008 (UTC)

Hmm... the same reaction should actually occur in certain fruits like cranberries which contain vitamin C and benzoate (see Benzoic_acid#Biology_and_health_effects). Icek (talk) 02:28, 15 April 2008 (UTC)

And of course there is the likelihood that it will contain vast amounts of E-numbers, the safety of which is still hotly debated. Michael Clarke, Esq. (talk) 23:44, 14 April 2008 (UTC)

Especially 2.71828...? Seriously, saying this is superfluous, nearly all substances which we named so far have E numbers, and E numbers do not imply that "the safety is hotly debated" (E 300?) - they imply that the European authorities regard it as safe. Icek (talk) 02:21, 15 April 2008 (UTC)

Relativity

I have been reading the book entitled Relativity The Special and The General Theory. I have come across the part about the derivation of the Lorentz Transformation. (If anyone happens the have this book, it's on page 35. This is the beginning of chapter XII.) It says "For the velocity $v=c$ we should have $\textstyle {{\sqrt {I-{\frac {v^{2}}{c^{2}}}}}=0}$..." This is when I=the length of a rigid rod. Yet, I don't see how this must equal zero for the fact that if v=c, then $\textstyle {{\frac {v^{2}}{c^{2}}}={\frac {c^{2}}{c^{2}}}=1}$. Therefore, if the length of the rod is I>1 then the result will be greater than 0 and things will be able to travel faster than the speed of light without violating anything. Also, if I<1 then it will be imaginary. Is there some rule that states I must always equal one? Whatever distance is being measured is always assigned a value of 1? Will someone please explain what I'm missing here? Thanks, Zrs 12 (talk) 18:05, 13 April 2008 (UTC)

The distance being calculated is the length of a 1 metre rod which is moving relative to an observer. The observer, because he is in another inertial frame will always measure something shorter than 1 metre. You are misreading the equation, the whole expression is the observed length of the rod. The "I" in your expression is not the length, it is the constant "1". This is just a common style of typesetting in old books. The correct expression is;

$x'={\sqrt {1-{\frac {v^{2}}{c^{2}}}}}$

From which you can see that the length of the rod is indeed zero if the velocity is C. SpinningSpark 18:21, 13 April 2008 (UTC)

Oh, ok. It confused me because earlier in the book, I think I was used as a variable. But I did have the equation $x'={\sqrt {1-{\frac {v^{2}}{c^{2}}}}}$ (It was given in the book). It just appeared that the 1 was actually a variable (I). Thanks, SpinningSpark. Zrs 12 (talk) 19:54, 13 April 2008 (UTC)

You are welcome. Have you looked at the Wikipedia article on the Lorentz transform? We also have an articles on Special relativity, General relativity and Albert Einstein which you might also find interesting. SpinningSpark 21:48, 13 April 2008 (UTC)

Bermuda Triangle and Continental Drift Question

I was wondering if anyone has done the research into the meteorite suspected of causing the extinction of the dinosaurs and the distance the continents have traveled since that event. Would the epicenter of such an event now be located someplace within the Bermuda Triangle region? If the meteorite was composed of a highly magnetic substance, would it be possible that the actual meteorite is embedded someplace below the Earth's crust and somewhat stationary position and as the continents continued to drift away from the original impact it would now be somewhere in the region we call the Bermuda Triangle?

It seems as though the distance the continents traveled between that meteorite event and today would be fairly easy for someone to calculate. Just a curiosity for me but if there is a co-relation then it might explain some of the odd effects noted in that region of the world.

If there is someone who can do the calculations on this and drop me a note it would be nice.

Thank you,

Randall Arthur—Preceding unsigned comment added by 75.165.48.237 (talk) 18:34, 13 April 2008 (UTC)

It is just offshore in Yucatan, Mexico. See Chicxulub crater. SpinningSpark 18:39, 13 April 2008 (UTC)

Actually, I believe when the meteorite hit, it the crater overlapped the land and sea. Mac Davis (talk) 06:48, 14 April 2008 (UTC)

And the Bermuda Triangle is interesting only for pseudoscientists. Carl Sagan opened The Demon-Haunted World with a similar story about Atlantis. Imagine Reason (talk) 19:17, 13 April 2008 (UTC)

By the way, it is a bad idea to post your e-mail in a public place like Wikipedia so I have removed it. SpinningSpark 18:39, 13 April 2008 (UTC)

Hi. Although this is just speculation, people think it might be methane clatherates. These are released when it warms, and if a fisherman picks it up then it will fizz away on the deck. If a ship encounters a bed of methane claterates being released then the ship might start to sink, and if the ship sinks then anyone that jumps out to save themselves may sink too as the methane relieves the water of most of its bouyancy. Thanks. ~AH1^(TCU) 00:15, 14 April 2008 (UTC)

Clathrates bubbling up from the ocean floor would not create such a dense foam that the ship would sink. Is that what you mean? Clathrates form on the ocean floor, how would it get on the deck? Mac Davis (talk) 06:48, 14 April 2008 (UTC)

Note that Wikipedia has got an article on methane clathrate. Regarding the original question, I think the meteorite is expected to have evaporated completely, but if the meteorite penetrated the tectonic plate of the lithosphere and got stuck in the asthenosphere below, then it probably isn't at the same position anymore as the asthenosphere can be expected to move even faster than the lithosphere (it is semi-liquid). Icek (talk) 11:44, 14 April 2008 (UTC)

I once saw a great map that showed all recorded shipwrecks in the Atlantic. It was a great map because the triangle did not show up at all. If you didn't already know about it, it would never have occurred to you to think that the area was 'special' in any way. I wish I could find that map now, but I can't. APL (talk) 14:31, 14 April 2008 (UTC)

On the topic of embedded in or below the crust, continental drift will move that part along with the continent, so it will stay in the same position relative to the continent, and not be moving further and further out in the ocean. A large chunk of iron could cause a magnetic and gravitational anomoly, but only cause a problem for ships if they ran into it! Graeme Bartlett (talk) 12:20, 15 April 2008 (UTC)

Hi. To answer the part about how the clathrates get on the deck, fisherman scoop them up in nets accidentally, and alarmed fisherman usually throw it back quick when it starts to fizz away on the deck, the book I was reading said. Also, global warming scientists fear that billions of tonnes of methane may be released by these clathrates, and that a few thousand years ago a slip in the clathrate-ridden rockbed occured, and sent a tsunami from Storegga to norway, hundreds of feet high. Also, apparently chathrates are flaring up in the Caspian sea, sending fire plumes hundreds of metres high. Thanks. ~AH1^(TCU) 22:26, 15 April 2008 (UTC)

Calcium Gluconate Illustration

I asked a while back if someone could help me map out the chemical structure for the supplement Calcium Gluconate. I was given assistance and shown how someone would write out it's formula, but what I was really looking for was Calcium Gluconate illustrated in the form that a molecular editor, like BKchem would show. What with the polygons and lines and what not. Any direct link to an illustration of Calcium Gluconate, or if someone could clearly explain how to do find it would be very much appreciated. —Preceding unsigned comment added by 76.177.106.51 (talk) 21:10, 13 April 2008 (UTC)

I think what you are looking for is in this [8]. We also have an article on Calcium gluconate SpinningSpark 21:20, 13 April 2008 (UTC)

Actually, not quite. That's what I was directed to before, something along those lines. I'm looking more for something like this [9]. Illustrated more along those lines. I would assume you could turn it into that? From text form to drawn out like I've linked? —Preceding unsigned comment added by 76.177.106.51 (talk) 21:36, 13 April 2008 (UTC)

Are you not seeing the diagram at all in the NCBI Pubchem data sheet? Perhaps you have a browser problem. If you do see it, explain why it is not what you want. SpinningSpark 22:01, 13 April 2008 (UTC)

I think I see now what you're getting at. I may have known the answer all along. It seems that it is that simple drawn out. I thought it might be a little more elaborate, like the link I provided, like Miconazole is shown. Not as simple as left to right. If that's it, then that's it. —Preceding unsigned comment added by 76.177.106.51 (talk) 22:25, 13 April 2008 (UTC)

April 14

how was leika the space dog "supposed" to die?

did they intend for laika to starve to death or what? —Preceding unsigned comment added by 79.122.58.58 (talk) 01:22, 14 April 2008 (UTC)

According to Laika, The Russian scientists had planned to euthanize Laika with a poisoned serving of food. --Bavi H (talk) 02:02, 14 April 2008 (UTC)

Is this true?

Is this video [10] at all true? Could you use a cd-rw to do this? thanks everyones —Preceding unsigned comment added by Its hard to believe (talk • contribs) 11:01, 14 April 2008 (UTC)

Hmm, did you read the comments? Like the parts that even getting a reflection of the laser into your eye for 1/1000 of a second can cause permanent blindness? Aeluwas (talk) 11:52, 14 April 2008 (UTC)

Thats not really answering the question. I did read the comments but one can never fully trust them, that is why I asked here. I am simply looking for a yes or no, although this being the science desk I was hoping for some explanation of the device, and anyones thoughts on other similar things. Thanks all —Preceding unsigned comment added by Its hard to believe (talk • contribs) 15:22, 14 April 2008 (UTC)

There was an article about this in Make Magazine recently. Apparently it's completely true that you can get lasers capable of doing things like popping dark colored balloons and lighting matches out of a dvd burner. (A couple hundred mW.) You'll need to supply your own power supply, of course. Obviously, you'll want to make sure you've got the right eye protection for this. Accidentally pointing this at a shiny object could be very bad. (Your eye protection needs to match the frequency of the laser you're using. Otherwise it does nothing.)

"Could you use a cd-rw to do this?" Yes, but unless you're familiar with handling high powered lasers you shouldn't. According to the WP article CD-RW drives use infra-red lasers which, of course, are invisible. Besides being less fun, a non visible laser can be dangerous simply because it's hard to tell if it's on. Our article on DVDr implies that it uses a visible red laser. Still might blind you, but at least you can tell if it's on. APL (talk) 15:59, 14 April 2008 (UTC)

Note that most or all DVD drives also need a infrared laser so they can read and (for DVD+/-RW and combo drives) write CDs (read the warning labels, they will usually say visible and invisible). Whether they use a seperate laser or simply have a way of changing the frequency of a single laser I'm not sure although from a quick Google it's apparently the later. Also bear in mind you will almost definitely need a R/RW laser since they are AFAIK much higher power. Nil Einne (talk) 19:18, 14 April 2008 (UTC)

There is a website that has pretty strong laser pointers here: http://www.dragonlasers.com/catalog/index.html I'm not sure if they are strong enough for burning anything, maybe they are just extremely expensive, but at least they have some kind of protection. --helohe (talk) 21:40, 14 April 2008 (UTC)

What exactly happens when you say "Well hello, newly constructed neuropathway!"?

<moved from miscellaneous desk Julia Rossi (talk) 11:55, 14 April 2008 (UTC)>
Does a new neuropathway form "recognizing" the acknowledgement unbeknownst to the original , kinda like a babys relation to it's birth certificate? Or somehow evolve by assimilating the new information into it's chemistry? Does it "know" what I'm hoping to achieve with this question and then question "itself" philosophically? Does it gain a new mind? Is all mind chemistry? Sam Science (talk) 19:21, 13 April 2008 (UTC)

I have no idea what you're trying to achieve with this question. I assume you're talking about whether or not there's a paradox in self-reference in the brain, like if I think about making a connection and a connection is made, I can form a contradiction. Well, it doesn't appear possible, for two reasons. First is that we don't appear to have any conscious feedback about what is going on in our brains, so we have no awareness as to the connections that are made. Indeed, to have such awareness, circuitry would have to be modified whenever circuitry is modified. This doesn't necessarily cause a paradox because of the second reason: normalization. It appears that most processes in the brain are normalized - that is, nerve cells are not usually overwhelmed or underwhelmed by the signals they receive, so even if one were to form an infinite feedback loop in the brain, the signal would either reach a peak and stay there or fade as new signals come into play. The only other possibility may be cell death or pruning of a now-useless connection. SamuelRiv (talk) 01:45, 16 April 2008 (UTC)

I'm not exactly sure what I was trying to achieve here either. Self referential puzzle? Finding the "Planck root", if you will, of all conscious phenomona? Existential crisis? Not sure. It just gripped my mind a few days ago and wouldn't let go. Thank God for you guys! Sam Science (talk) 01:58, 16 April 2008 (UTC)

Red deer

The youngs are called both calves and fawns in this article. The first seems to be the usual term; is the latter a correct variant or a mistake? --KnightMove (talk) 12:37, 14 April 2008 (UTC)

Fawn (noun): a young deer; especially : one still unweaned or retaining a distinctive baby coat. (Merriam Webster) --121.83.135.121 (talk) 13:57, 14 April 2008 (UTC)

Thx, but this doesn't help. Depending on respective species, young deer are called fawn or calf, see Deer#Etymology. The question is whether fawn is accepted for Red deer, where calf is the most common term, or not. --KnightMove (talk) 15:11, 14 April 2008 (UTC)

The right place to raise the issue of which to use in the article is, of course, the article's talk page, here. Another good place to go is the project page of any WikiProject that has staked a claim on that same talk page. I have gone to Wikipedia:WikiProject_Mammals and asked if someone would reply here. (My opinion doesn't count, but I call pretty little spotted critters of that kind fawns.) --Milkbreath (talk) 15:33, 14 April 2008 (UTC)

This says that both are acceptable. Michael Clarke, Esq. (talk) 22:33, 14 April 2008 (UTC)

Aspartate-tRNAAsn ligase

Aspartate-tRNAAsn ligase catalyzes the binding of aspartate and tRNA(Asx) without discriminating between tRNA(Asp) and tRNA(Asn). This page says "The aspartate-tRNA(Asn) is not used in protein synthesis until it is converted by EC 6.3.5.6 into asparaginyl-tRNA(Asn)." How is this possible? Is this done by the ribosomes or is it just that the reaction aspartate-tRNA(Asn) -> asparaginyl-tRNA(Asn) is so fast that the aspartate-tRNA(Asn) concentration is never high enough to worry about translation errors? Icek (talk) 16:35, 14 April 2008 (UTC)

Most probable year of peak oil

I have two questions regarding peak oil.

• The article Peak oil and Predicting the timing of peak oil gives all significant viewpoints about the timing of peak oil. Aside from some theories like "No peak oil", most researchers predicted the timing. According to the estimation by Association for the Study of Peak Oil and Gas, peak oil will occur in 2010. I want to know which year is the most accepted year?
• What will be the fate of industry after peak oil. How many years will it take for the industry to collapse from the year of peak oil? And a little final question, will airline industry survive after 100 years from when global oil peaks? Please tell. Otolemur crassicaudatus (talk) 18:38, 14 April 2008 (UTC)

I don't know mmuch about the expected timeline of peak oil, but I thought I'd answer your last question about the future of industries based on oil once we are running very low. I have no hesitancy in saying that they will survive. That sort of difficulty will just create a need for innovation, and will provide real motivation for companies to give serious funding to developing oil-free fuels. There will also be the normal market advantages: if there is no oil, the person/group that invents a way of fuelling cars, aeroplanes and all the rest wihout oil will stand to gain an enormous amount from their work, so expect solutions to be forthcoming. There is no reason AFAIK to suggest that there cannot be an alternative for oil in all its current uses. Michael Clarke, Esq. (talk) 20:25, 14 April 2008 (UTC)

I don't know if there is a most accepted year, it's such a complicated field which involves so much 'guesswork' (for the later of a better word) and so many conflicting factors, with such a variety of suggestions and so much politics, money and COI that there's probably none. Nil Einne (talk) 20:38, 14 April 2008 (UTC)

It is not right to say that airline industry will survive. As being politically anarcho-primitivist, I support peak oil and consequential industrial collapse. At present there is no fuel outside conventional fuels for aeroplanes. And the alternative fuels are not at the level to continue the airline industry. Alternative fuel development is in its rudimentary stage and there are several problems regarding this. Survival of industry after peak oil based on alternative fuel is a subject of science fiction. Otolemur crassicaudatus (talk) 20:49, 14 April 2008 (UTC)

While it is true that it is science fiction to speculate on how the fuel crisis will be overcome, it would be naive to think that it will not be overcome. Desire and necessity drive invention and creativity, and as long as there is demand for air travel, there will be air travel. As I said, there is nothing to suggest that it will be impossible to replace oil, even if it requires different replacements for the many different uses of oil. Michael Clarke, Esq. (talk) 21:33, 14 April 2008 (UTC)

And I'm sure you're aware of the irony of an anarcho-primitivist using the internet... Michael Clarke, Esq. (talk) 21:34, 14 April 2008 (UTC)

I'm hoping that the airlines are forced to go back to Zeppelins. They're a bit slow, but they make it up with class. APL (talk) 13:25, 15 April 2008 (UTC)

Whenever reading about peak-oil and post-oil worlds i'm always reminded of (I think) a Sheikh who said "the stone age did not end for lack of stone, the oil age will not end for lack of oil" (or words to that end). The Aviation industry certainly has challenges and aviation in the future might not be the same as aviation-today, it might be vastly different in ways we cannot imagine but it will exist. Might be worth having a read of the article Aviation history - quite interesting and has a section on peak-oil ny156uk (talk) 22:35, 14 April 2008 (UTC)

Biofuel is not the solution to continue the industry. For details see Biofuel#Sustainability_of_ethanol_production and Biofuel#Soil_erosion.2C_deforestation.2C_and_biodiversity. Using biofuel to continue the industry is the subject of science fiction and some fringe theorists. Otolemur crassicaudatus (talk) 10:06, 15 April 2008 (UTC)

What a strange analogy. Did stones suddenly stop being near-free and become something that needed to be manufactured at great expense? APL (talk) 13:25, 15 April 2008 (UTC)

Thinking about that for a moment, If I can anticipate the response I'd like to add that I'm pretty sure that society uses far more stones today than it ever did back when we were throwing them at woolly mammoths. APL (talk) 13:28, 15 April 2008 (UTC)

No the point of the analogy is not about scarcity it is about development...The end of the stone age was not a result of running out of stone, it was a result of technological advancement. Similarly the quote suggests that we will not leave the oil-age because of a lack of oil, we will leave it because of technological advances. I'm inclined to agree with that logic, albeit it that it is reliant on believing mankind has the ingenuity to find a suitable replacement within the timescales of the predicted-oil we have left to utilise. Simple economics tends to suggest scarcity and high-demand increases prices, and that should spur on searches for replacements and/or reduce consumption over time as people are priced out of using oil and so seak out alternative (either in energy source or reduced use of energy) ny156uk (talk) 16:31, 15 April 2008 (UTC)

Remember that what's "magic" about oil is that it's essentially a free form of energy. In its refined forms it's great for fueling cars and trains and aeroplanes, but what's vastly greater about it is that it taps millions of years of accumulated, concentrated solar energy. It costs a certain amount of money to get it out of the ground and refine it, but the cost is far less than its worth in dollars per joule. (That's precisely why the oil companies are so profitable.)

There are lots of alternative fuels we might use. The important question isn't whether they'd work, or how compatible they are or aren't with our existing fuel distribution infrastructure. The key question is whether they're an energy source or a transfer medium. If they're just a transfer mechanism (like hydrogen or electricity), then their use as a fuel merely begs the question: where does the energy come from to create them?

There are lots of sources of energy, too, of course, but when it comes to the long-term prognosis for our energy-hungry lifestyle, only one characteristic matters: is it renewable/sustainable, or not? Right now, we're still very heavily dependent on nonrenewable energy sources. The question is, can we wean ourselves off of these, and on to wholly renewable sources, before we burn up all the nonrenewable sources, and crash? (An important sub-question is, do we get there by finding additional renewable sources that will enable us to match our current nonrenewable usage rate, or are we going to have to figure out how to get by with less?) —Steve Summit (talk) 01:23, 15 April 2008 (UTC)

The answer is no. Expect some fringe theorists, Kardashev scale etc. it is not possible to find additional renewable sources that will enable to match the current nonrenewable usage rate. Otolemur crassicaudatus (talk) 10:17, 15 April 2008 (UTC)

Well, there are degrees of "renewable". Not even the Sun is renewable forever. But if it's good enough for an energy source to go for quite a long time -- long enough, hopefully, for our descendants to figure out something else before it's all gone -- then breeder reactors should last us quite a while, especially if we use both the U-238 and thorium cycles. --Trovatore (talk) 18:04, 15 April 2008 (UTC)

Reading and near-sightedness

It is often said that if you read a lot when you are young, you have a higher chance of becoming near-sighted. Is this true? I mean, has there been studies on this that have shown causality? I sort-of find it hard to believe that simply focusing on something that's near to you fundamentally changes the shape of the eye and the lens. It does fit me, I read heckuva lot as a kid, and if you're more than 2 meters away from me (and I don't have my glasses), I basically have to identify you by voice. Then again, pretty much everyone in my family has glasses so that'd be an argument for genetics (although, everyone in my family reads a lot too...) 83.250.207.154 (talk) 18:45, 14 April 2008 (UTC)

I personally don't think so, but I don't have any evidence to back it up. I'm going with genetics all the way. Neal (talk) 19:07, 14 April 2008 (UTC).

There is a section on this in the article for Near-sightedness. I, too, read many books as a child. However, my myopia is so severe (everything beyond 5 centimeters is horribly blurry) that I highly doubt something as simple as reading could have caused it. Since myopia is caused by the elongation of the eye, and increases steadily over time regardless of activity (at least in my case), I would have to say it has a lot to do with genetics. 206.252.74.48 (talk) 19:56, 14 April 2008 (UTC)

I have coloboma of the chorrhoid layer and have always had to read very close; I've been reading extensively since age 3 with no chnge in my eyes. So, I agree, it isn't always the case.

I use to tell people that it was like a baseball pitcher's arm, and mine was like a Nolan Ryan. I think that's true - just as some pitchers can throw gobs of innings, others can't. Similar, some heavy readers need reading glasses, others don't. —Preceding unsigned comment added by DTF955 (talk • contribs) 21:18, 14 April 2008 (UTC)

What if it's working the other way: those children who have myopia can't watch objects that are far from them so instead read books which are close? – b_jonas 09:01, 15 April 2008 (UTC)

But that wouldn't explain children who had regular eye tests throughout childhood (as are freely available in the UK, for example), read a lot throughout childhood, and whose vision can thus be known to have been good before they started reading intensely. Certainly I know that chickens tend to develop myopia if kept in conditions that prevent them looking at distant objects when they're still developing, and this can be resolved by allowing them occasions to focus on the distance. In humans it is harder to resolve, and too much close-focusing without distance-focus is nowhere near the whole picture, but there is some evidence that it can be a factor. I'd guess that there's a strong genetic component that affects whether you're susceptible to certain sorts of short-sightedness, and that certain forms can be exacerbated or even caused by too much close-focusing without distance-focusing, if you're genetically susceptible, but it doesn't cover all readers or all those with sight problems. 130.88.140.1 (talk) 10:42, 15 April 2008 (UTC)

Strawberry flavouring

Why is it so difficult to chemically replicate the flavour of strawberries? I ask because no strawberry-flavoured food that I've ever eaten tasted like strawberries, yet I've had other foods that were flavoued artificially and were accurate gustatory imitations. is strawberry just a very compex taste? Are certain tastes easier to synthesise than others? Michael Clarke, Esq. (talk) 21:29, 14 April 2008 (UTC)

Yes, some are easier than others. Artificial vanilla is wonderful, while artificial cherry and grape are also awful, or at least completely unlike the natural flavors. I don't know why, however. StuRat (talk) 23:27, 14 April 2008 (UTC)

I think it would have to do with the complexity of the chemical reactions. For example, vanilla's taste and smell is primarily from vanillin. By contrast, the smell of a strawberry is supposed to be the result of a reaction between 350 different chemical reaction. According to Fast Food Nation:

A typical artificial strawberry flavor, like the kind found in a Burger King strawberry milk shake, contains the following ingredients: amyl acetate, amyl butyrate, amyl valerate, anethol, anisyl formate, benzyl acetate, benzyl isobutyrate, butyric acid, cinnamyl isobutyrate, cinnamyl valerate, cognac essential oil, diacetyl, dipropyl ketone, ethyl acetate, ethyl amyl ketone, ethyl butyrate, ethyl cinnamate, ethyl heptanoate, ethyl heptylate, ethyl lactate, ethyl methylphenylglycidate, ethyl nitrate, ethyl propionate, ethyl valerate, heliotropin, hydroxyphenyl-2-butanone (10 percent solution in alcohol), a-ionone, isobutyl anthranilate, isobutyl butyrate, lemon essential oil, maltol, 4-methylacetophenone, methyl anthranilate, methyl benzoate, methyl cinnamate, methyl heptine carbonate, methyl naphthyl ketone, methyl salicylate, mint essential oil, neroli essential oil, nerolin, neryl isobutyrate, orris butter, phenethyl alcohol, rose, rum ether, g-undecalactone, vanillin, and solvent.

So yeah, it's no easy feat to replicate the flavor or smell of a strawberry. bibliomaniac15 Hey you! Stop lazing around and help fix this article instead! 23:35, 14 April 2008 (UTC)

Contrast the above list of ingredients with Pineapple, banana and a lot of other fruits that can have thier flavoUrs replicated by one ester. The esterification reactions are a very common high school chem experiment, differences in one carbon can result in a totally different smell.

Oh and btw that list by Fast Food Nation in no way means that artificial strawberry is less healthy than natural strawberry flavour.--Shniken1 (talk) 10:54, 15 April 2008 (UTC)

Does anyone know where to find strawberry-flavored strawberries? I find that most strawberries taste more like straw than like berry. --Trovatore (talk) 18:19, 15 April 2008 (UTC)

Supermarket strawberries are so tasteless because they have to be grown real fast to get that ridiculously low price. Although they have managed to develop varieties that turn red fast, there is insufficient time before picking for the flavours to develop. My sister recently gave me some from a small independant grower in cornwall (England) last time I visited. Delicious, what a surprise, I had forgotten what a proper strawberry is actually supposed to taste like. So my answer is Cornwall, but there are probably other places you can get them. SpinningSpark 18:45, 15 April 2008 (UTC)

I remember a controversy (possible lawsuit?) back in the eighties or so about "natural cherry flavor". IIRC one manufacturer of natural cherry flavor sued another one, claiming the second one's process was insufficiently "natural". The thing that stuck with me was that (again, if I recall correctly) neither plaintiff nor defendant used any actual cherries to make "natural cherry flavor" -- they used bitter almonds, and somehow cleaved off the sugar molecule and the cyanide group from the amygdalin therein contained to make benzaldehyde. You would search the news stories in vain for any suggestion that benzaldehyde derived from almonds, even if natural and even if it tasted like cherries, was not natural cherry flavor. --Trovatore (talk) 20:58, 15 April 2008 (UTC)

Dawkins, genes, sexual selection, and women

I was reading The Selfish Gene and was struck by the passage where Dawkins raised the question of why human females are the ones who have to wear make up, dress up, doll up, etc. when in almost every other species, the worth of the female egg and related factors has made females the sought after sex. Thus we have the peacocks and big cat suitors who have to compete for female attention by growing flashy tails or muscles. The sought-after sex gets to be drab because they don't need to be sexually attractive. Why the opposite in humans? Imagine Reason (talk) 22:21, 14 April 2008 (UTC)

I hope someone chimes in with a good answer. All I can say is, Dawkins may be engaging in cultural tunnel vision. There are other cultures where females do look drab deliberately, ranging from wearing conservative clothing and scarves to completely covering themselves from head to toe, with no skin visible. The same is true for any culture in history that regarded women as property. ~Amatulić (talk) 22:27, 14 April 2008 (UTC)

Good point, but it's also not true that all male-dominated cultures make women drab. The women in late feudal China suffered things like footbinding, but they were doing it to doll up. And even if it is only Western culture that sees women pretty themselves while metrosexual males are looked upon suspiciously, why? Imagine Reason (talk) 23:05, 14 April 2008 (UTC)

(After Edit Conflict)

I would think that in humans it is different yet similar. Due to our evolutionary adaption, we show our peacock feathers in a different way. Such as it is considered, in virtually all cultures, that the male should be the persuer of females. That is; men should woo women using gifts, poetry etc., and this is why people often think women being forward to be unusual. I think that women using their physical attractiveness is more to do with the human male's "visual" sexuality. Which, as far as I know, is to do with the ease of discerning "the hairless ape's" suitaility for childbirth by looking. I may be rambling a bit, but I find the questing fascinating! :-) Any more ideas? Fribbler (talk) 23:08, 14 April 2008 (UTC)

I would say the diff is that for most species the male is simply a "sperm donor", so their health and fitness (demonstrated by some elaborate display), is the only important factor to consider. In humans, on the other hand, males have historically been important in providing for the wife and children, as well. This means that being a good provider is also an important trait. Faithfulness is also important, since children wouldn't have been likely to survive, until relatively recently, if the man runs off with some other woman. And we can also throw in kindness, since a man who beats his wife or children would decrease their chances of passing on their genes. So, all of this means that attractiveness of a male is only one of many factors women considered.

Conversely, if the man is going to invest a lifetime in raising children with a woman, he needs to be sure she is a good choice, and youth and attractiveness are indicators of the woman's health and ability to have children. In the "sperm donor" spcies, on the other hand, if a male chooses a poor mate, it's only 15 seconds out of his life, so no big deal. This makes them just go for quantity and not much care how attractive, young, or healthy any female is. StuRat (talk) 23:10, 14 April 2008 (UTC)

Good points, all, but none of the features mentioned are remotely exclusively to humans. In particularly, males pursue in most other species and monogamous and costly pairings are common in nature. Imagine Reason (talk) 23:25, 14 April 2008 (UTC)

Indeed. But were you not looking for the aspects that were unique to humans? That we were unusual? I thought we showed that the same rules apply. Albeit differently?Fribbler (talk) 23:28, 14 April 2008 (UTC)

Sorry, I don't understand. Yes, I'm looking for the aspects that differ, but I don't see them yet. I don't see what has driven the females to pretty themselves up especially in societies that treat them more or less equally. Imagine Reason (talk) 23:36, 14 April 2008 (UTC)

Ah, I think I see (though maybe not :-)) I'm going to focus in on the societal issue. In unequal societies (by western standards), women are considered to be too sexually seductive to be dislayed in public. That is, their attractiveness would lead to them being raped indisciminately (a poor opinion of the males in these areas, in my opinion), and it isn't particularly a question on genetics as it is a question on culture. Hence the 'drab' clothing or appearance. It is considered that women who display themselves would invite 'unwanted attention' from men other than their husbands. Am I getting close to answering your question at all? Fribbler (talk) 23:46, 14 April 2008 (UTC)

Indeed culture is keeping those women oppressed, but I guess my point is that other animals do not need to force the issue for females to be drab. The natural state for other females is for males to be physically attractive. Perhaps in men appearance has fallen behind as an indicator of reproductive fitness, while it remains a good indicator in women? Imagine Reason (talk) 00:16, 15 April 2008 (UTC)

My take on the whole thing would be that even though the females may have to dress up and look nice to attract a mate, this is no different from the animal kingdom. Men still compete for women, pretty viciously at times, and often go through elaborate courting processes as was mentioned above. The women dress up in order to attract the best possible mates, as if they look bad then the best mates will ignore them. This is the same in the animal kingdom: the males don't put on displays for the females they don't want. I would interpret the female "dolling up" as similar to preening in female animals, while it is still the male of the species who must go through the elaborate courtship rituals and display his worth to the female. I think human courtship has gotten to the point where in many societies there is not a strict male or female balance of power. To borrow from the frogs and the way male frogs will guard a spot for the female to lay her eggs, and then the female will choose one, in humanity who would take which role? There are many deep sociological issues here, especially involving the subjugation of women. Often men have been able to choose women on a whim, and the women had no say. But now, women are increasingly in control of relationships: it's the man who proposes, and the women who rejects. seems quite a bit like the frogs to me, once you get past the complicated nature of human interaction. Michael Clarke, Esq. (talk) 23:58, 14 April 2008 (UTC)

Indeed, Mickey C. Though I would say that male choice of a partner on a whim was limited to the nobility of world nations. It is indeed very sociological, and complex! We are a complex species, that twists the rules of nature to suit ourselves. Fribbler (talk) 00:09, 15 April 2008 (UTC)

So you're saying that men are doing similar things to building nests. Hmm. Imagine Reason (talk) 00:16, 15 April 2008 (UTC)

Oh yes! Definately! Nest building shows suitability as a providing parent. The human male uses his status as a nest. Displayed by car ownership, house ownership, income etc.; nest building is merely a sign of providence. It all boils down to what support mechanisms one can provde to ones offspring. The requirement adapts to situations Fribbler (talk) 00:23, 15 April 2008 (UTC)

Also note that many other animals don't have flashy males. There are some birds (like penguins) and many mammals (like cats and dogs), where it's not even easy for us to tell the males from the females without "noting their particulars". StuRat (talk) 01:56, 15 April 2008 (UTC)

Yeah, I need to remind myself of that. I think though those females are not flashy either. Imagine Reason (talk) 03:07, 15 April 2008 (UTC)

Just a note, but Darwin himself noted this difference between humans and other animals in Descent of Man when he really exposited on sexual selection the first time. I forget whether he gives his own explanation or not. --Captain Ref Desk (talk) 02:34, 15 April 2008 (UTC)

I've always thought that a man's beard was akin to to a lion's mane in flashiness. Men tend to have naturally longer eyelashes and hairier bodies. Remember also that physical competition is part of the equation so stronger looking men tend to be more attractive to women. This is, of course, the natural state and cultural training can adjust such things. — Ƶ§œš¹ _{[aɪm ˈfɻɛ̃ⁿdˡi]} 21:09, 15 April 2008 (UTC)

I don't know what Dawkins take on it is (and he's not the be-all-end-all of interpreting evolution, BTW), but one thing to keep in mind is that in other species (even in closely related primate species) the female has a very visible display of estrus, for example getting bright red, swollen reproductive organs (I would have provided specifics, but I don't want to Google "red swollen reproductive organs" ;), presenting themselves in a certain way, etc. The concept is that if you can successfully reproduce less than 10% of the time, you don't want to be harassed by males seeking to mate the other 90% of the time. In addition, if estrus is staggered (different females come into heat at different times) you'll get better mate selection if the males know who to fight over. Note, however, that Humans are distinctly lacking in any sort of noticeable estrus signal. One theory floated on this is that humans benefit from the ambiguity over fertile times - if the male doesn't know when you're fertile, he'll stick around and provide food/other social benefits for you. Also, if he's clueless as to who you mated with when you were fertile, he won't know which matings were successful, so he can be conned into helping raise Mr. Svelte's child. So there may be an evolutionary benefit to keep looking like you're young, fertile, and sexually receptive. (For a tangible example, go to any college bar - attractive women can go *years* without paying for any drinks.) -- 128.104.112.85 (talk) 00:01, 16 April 2008 (UTC)

Macaw - why's she so bad at walking on the floor?

When she walks on my hardwood floors or on something like a tabletop, she walks like a person in shoes would walk if they were on an ice rink. Seems to be a real effort for her. There's nothing wrong with her legs and I keep her toenails well trimmed. It just seems to be a smooth surface problem for her. Any ideas? —Preceding unsigned comment added by 84.65.178.125 (talk) 23:22, 14 April 2008 (UTC)

It's probably because she evolved to grasp branches with her talons, so they are not designed for walking along polished floors. Michael Clarke, Esq. (talk) 23:48, 14 April 2008 (UTC)

Indeed, the curved talons of a bird are designed to cling to branches and not smooth flooring. Fribbler (talk) 23:56, 14 April 2008 (UTC)

It isn't even a question of "cling"; the bird has to spread its toes uncomfortably wide to stand upon, let alone walk upon, a flat surface.

Atlant (talk) 12:18, 15 April 2008 (UTC)

Due to the curvature of the talons, a parrot is physically unable to lay its feet flat against a hard, smooth surface. The pressure on the talon tips causes the end of the toe to lift and bend backwards at the joint - and I don't think that parrot toes were designed with bending backwards in mind. I'd imagine that it's pretty uncomfortable to walk like that for long, lack of traction against the surface aside (yes, it probably is like walking on ice to them). That said, I've owned fully-flighted small parrots (various species) that skittered and wobbled around on a glass coffee table I used to own for tens of minutes at a time whilst playing when the option was there to go somewhere else. --Kurt Shaped Box (talk) 20:33, 15 April 2008 (UTC)

Macaw question 2

How is it possible for my Macaw to eat a habanero pepper like a human would eat an apple without being effected by the heat at all? --84.65.178.125 (talk) 23:39, 14 April 2008 (UTC)

Im guessing it's to do with their tongues' perception of the Capsaicins in the chilli. They may not react to it as a mammal would. Fribbler (talk) 23:52, 14 April 2008 (UTC)

I find it odd that your macaw can do that. I had a canary once, who would eat nearly anything that was roughly the size and shape of a seed (bread crumbs, pieces of nuts, rice grains, etc.). Well, as you know, the heat in jalapeño peppers reside in the seeds. He tried eating a jalapeño pepper seed once. Just a few bites with his beak, then a violent shake of his head. He never touched a jalapeño seed again. I suspect he felt it.

Maybe your macaw just loves the sensation of "hot" foods, like some humans do. ~Amatulić (talk) 00:07, 15 April 2008 (UTC)

And how exactly did that seed get in the bird cage ? StuRat (talk) 01:46, 15 April 2008 (UTC)

It didn't. The canary only used his cage to sleep. He spent most of the rest of the day on a newspaper we kept on the countertop, admiring his reflection in the toaster, and making forays elsewhere for tidbits. Once when cutting up jalapeños, he made off with a seed. ~Amatulić (talk) 20:11, 15 April 2008 (UTC)

I wouldn't worry about it. Some commercial bird seed mixes contain dried chili seeds. My lovebird used to eat the stuff with no complaints. Don't you have to feed chillies to red canaries in order to maintain their colour anyway? --Kurt Shaped Box (talk) 20:40, 15 April 2008 (UTC)

The article on Capsaicins says in its opening paragraph that it is a mamallian response. I don't know better, but it would seem that birds could eat them easily. Maybe your bird didnt like the taste? Fribbler (talk) 00:13, 15 April 2008 (UTC)

April 15

small cities

i am not a person who complains often, but i am not happy because of the simple fact that i cannot find any type of information/research reffering the city of San Antonio Tariacuri, in Michoacan Mexico. I have searched for many hours trying to find any information at all an i am still nto capable of finding anything. The only anwser that i can think of to my simple question, "why am i not able to aquire any information on the city thta i am trying to find?", and the anwser the only anwser i have is.. because it is because the city that i am looking for is too small. i refuse to believe that such a detail that small denies anyone the simple request to find information on such a simple request!!!!!! so basicly my question to you is, can you please add information about the city, San Antonio Tariacuri located in Michoacan Mexico? —Preceding unsigned comment added by No one can judge me (talk • contribs) 01:02, 15 April 2008 (UTC)

• A Google search gave me this: [11]. It gives the location, population, and elevation, with schools listed at the bottom.

• Here's the phone info: [12].

• Here's the maps, airports, nearby towns, and weather: [13].

• Beware that the town is often called simply "Tariacuri" (or "Tariácuri").

What other info do you need ? StuRat (talk) 01:29, 15 April 2008 (UTC)

Maybe the OP was complaining the is no information on Wikipedia. In which case the OP is welcome to start an article. SpinningSpark 16:17, 15 April 2008 (UTC)

Picture of Blubber

Does anyone know where I can get a picture of blubber that's usable for wikipedia? FromFoamsToWaves (talk) 01:23, 15 April 2008 (UTC)

In the future if you have any kind of question related to Wikipedia, use the help desk. With that said, please feel free to read WP:IMAGES and fair use criteria for images. Wisdom89 _{(T / ^C)} 01:33, 15 April 2008 (UTC)

The best way, of course, is to find somebody willing to release their rights on the picture to the public domain. Also, I know that it's unlikely, but, ideally you yourself could be the copyright holder/owner of the image if it is self-made. Wisdom89 _{(T / ^C)} 01:35, 15 April 2008 (UTC)

This pic any good to you? --Kurt Shaped Box (talk) 22:21, 15 April 2008 (UTC)

Oh boy! Blubber!FromFoamsToWaves (talk) 00:12, 16 April 2008 (UTC)

Motivation

Okay, you may speedy-delete this question if you want to (part of the answer could be medical advice to give you some good reasons), but I nevertheless mean this dead serious. Why is it that I am sitting here, doing lots of unuseful stuff (like writing this question =) and simply cannot motivate myself to do all those things that I really really want to do to be successful? I have a huge library about personal motivation, I've read, heard and researched lots and lots of this stuff, I have a clear goal (maybe too many?), there are plenty of "carots" and "sticks" in my life, I'm pretty intelligent (Mensan if that matters), I have enough time and talent, cool friends and many good opportunities in almost every area. Judging from what others tell me I could be almost anything I want (as of now), but I'm still sitting here, in the middle of the night, depressed of everything I've missed and done wrong. I'm at a point to believe there may be nothing more that I could do, as I've read and tried pretty every motivation trick/programme/guru/medication/etc that I could think of. With every time I fail to be the self-disciplined guy I so desperately want to be I'm more afraid of moving on and/or trying again, but I simply don't know why. In my native language I'd say that "I'm at the end of my latin". So if you ever were in a similar situation or you've got anything that could help me out, I owe you. And I mean that. Thanks in advance. Endymi0n (talk) 02:31, 15 April 2008 (UTC)

I'm not going to comment on anything that relates to prescription medicine and the like. However, I will say that I understand where you are coming from. Here is some trivial (but helpful) advice. Try approaching the day in steps/small strides. Instead of thinking what ultimately needs to be done, or worrying about the final product, concentrate on the steps. Make yourself a small to do list, and follow it sequentially. I know this sounds cliche, but it's useful. Cheers mate. Wisdom89 _{(T / ^C)} 02:56, 15 April 2008 (UTC)

And to go along with small steps, I propose small rewards. The eventual rewards of, say, establishing a succesful career, may be years away, with much hard work before you get there, and you may not be willing to work for such a distant reward. So, set sub-goals with rewards at each level. StuRat (talk) 13:01, 15 April 2008 (UTC)

I must have read your very advices more than a thousand times, yet it seems these techniques (small steps, small rewards) were the only ones that really helped me. Maybe it's really like "repetition is the mother of skill" (Tony Robbins =) and I have just have to apply it to my life over and over again. Many thanks though, I hoped for a different answer (one that I didn't know or think of), but you pointed out a very important fact for me! Endymi0n (talk) 15:40, 15 April 2008 (UTC)

Probably because you've been told since you were about five that you need to be a 'successful' person in order to have an enjoyable life, but your subconscious just doesn't believe it. Your subconscious is more concerned will real issues like food and sleep and warmth and social contact than these constructed fabrications of value like 'having a succesful career', 'having a successful marriage'. All that stuff is just filler for your obituary, and no one really cares about it. They just give it lip service because that's the way it's always been. I mean, by all accounts Bill Gates is the most successful man in history, yet who really respects or admires him? They may superficially admire his wealth and intelligence and business acumen, but he's not exactly a role-model and I doubt if anyone would want to be just like him. Vranak (talk) 04:38, 15 April 2008 (UTC)

Thanks Vranak - to clarify myself: I don't want to be as "successful" as Bill Gates and I don't measure success in money. You have to pay a price for everything and all money, no life and fun isn't a life that I'd be comfortable with. Though, to quote a line from one of the best songs I've ever heard (Switchfoot-This is Your Life, go hear it if you've ever felt like me!): "This is your life - are you who you wanna be?" - and I'm clearly not. I don't want to get religious here, but whoever gave me the gifts I was born with wanted me to do something good with it. My problem is that I don't know what I really want as I love so many extremely different things and I just wished I could do them all. I have worked as an author, church musician, graphics designer, film score composer, business consultant, flirting coach, film director, radio anchorman, web designer and singer/songwriter while studying engineering physics, musicology and media technology, but nothing to a level where I was ever satisfied with my life and/or achievements. I start something, get enthusiastic about it, finally get a bit bored when everyday life kicks in and then find something new that draws my interest. I feel so torn every day because in all those fields there's something I like that I just don't want to give up. I've made lists, spreadsheeds, mindmaps... but I just cannot decide what's my ultimate goal, the one that's "all or nothing", to get me started. So I'm sitting here, having aborted two study disciplines, watching all my peers and friends getting finished and starting a "life" while I'm still stuck in my self-built cage of missed opportunities. That's the story =) Endymi0n (talk) 15:40, 15 April 2008 (UTC)

Well, if you'd like to analyze your problem from a mathematical angle you might want to look at Game theory, risk and related pages. On a psychological basis unconscious mind and deferred gratification are worth a look. Simply put, your logical analysis does not coincide with your subconscious assessment. You know there's a healthy carrot in your future if you work hard, but your subconscious/unconscious mind sees and eats the chocolate cake in front of you. There are techniques like mind control to get the rest of the troops to agree with your reasoning. That's why breaking a big task into smaller ones sometimes works. The reward is moved a bit closer to the effort. If you are suffering from adult ADHD quite a few of those techniques won't work. As for depression, if you are talking of the non-clinical type, you might want to reexamine your goals and Value theory. Looks like your glass is always half empty instead of half full. Try this one: Tape a list somewhere so that it often falls within your field of vision. (The mirror so often recommended actually doesn't really work that well) Write on it "I'm a great guy/gal." and 3 things you have achieved or like about yourself then at regular intervals add 3 things you've done. (Every evening's recommended but not practicable for the busy/disorganized. Once a week's more like it). Start with little things like "I took out the trash." and head for the "got my dream job" once you've got the hang of it. —Preceding unsigned comment added by Lisa4edit (talk • contribs) 08:29, 15 April 2008 (UTC)

You say you are "sitting here, in the middle of the night". You could try changing your sleep pattern so that you get more sleep (even if you don't think you need it) - this could improve your motivation, mood and energy levels. Gandalf61 (talk) 09:54, 15 April 2008 (UTC)

Mm-m, Circadian rhythm. Try to turn off the looking at the past thing. Nothing you can do about it, let it go. Julia Rossi (talk) 12:16, 15 April 2008 (UTC)

Thanks. Conciously I DO know both of that. But when I'm in the wrong state (see below), I just don't care. I wish I could. Endymi0n (talk) 15:40, 15 April 2008 (UTC)

I relate strongly to what you wrote. Not that long ago I was diagnosed with Attention deficit disorder (non-hyperactive type). The diagnosis suprised me (I never considered myself inattentive) but it fits. Maybe it also fits for you? moink (talk) 12:24, 15 April 2008 (UTC)

Didn't want to mention it in the first place in fear of being speedied but yes, I'm diagnosed with ADD (non-hyperactive), bipolar disorder with ultra-rapid cycling and high IQ. I believe I was always kind of ADD, since that's not an illness but a different way of experiencing and doing things. BPD likely came from my way of (not) dealing with it, as I was nothing like that in my teen years. As a type, I'm rather optimistic =). Endymi0n (talk) 15:40, 15 April 2008 (UTC)

Majahapit civilisation

<already at Humanities desk - please do not crosspost>

Why does the sun make people happy?

After living in Alaska through a few long, dark winters, I learned from direct experience and observation that not having the sun around makes things pretty gloomy. One time during such a winter I walked into someone's house and they had one of those full-spectrum "happy-lights" and I immediately felt better. It really shocked me. I didn't even notice the light until after I felt its effect. Why in the world does the sun's light, or light similar to it, do this to humans? Wrad (talk) 02:14, 15 April 2008 (UTC)

See seasonal affective disorder. Vranak (talk) 04:33, 15 April 2008 (UTC)

You might take a look at the "pathophysiology" section of the Seasonal affective disorder page; it describes some of the theories about what relationship the sunlight has with psychological effects from a biochemical perspective. Note of course that SAD is an extreme form of the general observation. --Captain Ref Desk (talk) 02:40, 15 April 2008 (UTC)

This question is really a Science question, but I'd also remind you to beware of SAD. Imagine Reason (talk) 03:02, 15 April 2008 (UTC)

Sorry about that. It is a science question. I must have clicked the wrong thing. Wrad (talk) 04:18, 15 April 2008 (UTC)

Moved. BrainyBabe (talk) 06:44, 15 April 2008 (UTC)

What will happen if there would be an Ebola Pandemic

I was inspired by Dismas' post here and my seredipitous find in using the Random article button. Suppose the monkey infecting Ebola Reston virus mutated into a human infecting virus. Unlike its sisters, which is transmitted via bodily fluids, this one is airborne. What do you think would happen to society? Would all of humanity be wiped out? How fast would the infection be? I for one know that I would be dead by now if the virus did mutate as the strain is found here in the Philippines. I just want your opinions. Thanks.--Lenticel ^(talk) 08:43, 15 April 2008 (UTC)

The worst-case scenario could be the collapse of civilization (or reduction of it to a less developed level), but humanity would most likely survive due to genetic diversity. --193.16.218.66 (talk) 10:54, 15 April 2008 (UTC)

I suppose it depends on how much the virus mutates in that time. It's not inconceivable that, being airborne and highly fatal, if it mutated quickly enough to counteract genetic diversity and outbreaks happened simultaneously all over the world then it could wipe out a significant portion of humanity. But I'd expect there to be some survivors, even if it's only astronauts and people who have their own clean rooms. If the Black Death couldn't kill us off before medicine was really a science, I doubt any disease will be able to completely eradicate humanity nowadays. But we could be looking at a collapse-of-civilisation type scenario, and the airborn nature of the virus means it could linger in other animals, killing us off later. But I'd say that even if it did mutate incredibly fast there are always likely to be carriers. But I'm no Virologist. Michael Clarke, Esq. (talk) 22:05, 15 April 2008 (UTC)

All this talk reminds me of 12 Monkeys. Imagine Reason (talk) 22:19, 15 April 2008 (UTC)

Really? I thought Outbreak. Confusing Manifestation(Say hi!) 22:57, 15 April 2008 (UTC)

The incubation time for ebola is quite short: about 24 hours. After this time, the victim is quite ill and not really able to wander about and spread the virus. Combined with the high mortality, this attribute makes it somewhat more likely that the illness' spread would be largely self-limited and restricted to a few populated areas. – ClockworkSoul 00:26, 16 April 2008 (UTC)

Do hands get bigger with age?

If you buy a ring when you are 18, will it still fit perfectly when you are 50? I'm referring to men specifically, but women too. Thanks. 195.60.20.81 (talk) 09:08, 15 April 2008 (UTC)

I think bone growth stops when you achieved young adulthood so hands wouldn't grow bigger. However, it might grow bigger if you become obese.--Lenticel ^(talk) 09:31, 15 April 2008 (UTC)

Finger size can certainly change if you put on or lose weight, by enough to make a previously well-fitting ring difficult to remove or too loose for comfort. Resizing plain gold or silver band rings is very straightforward - the process is described here. Resizing rings with stones is more difficult, but possible. Our article on ring sizes says that rings made of titanium or tungsten cannot be resized. Gandalf61 (talk) 09:41, 15 April 2008 (UTC)

Possibly hands develop size through muscle increase and skin thickening as the body matures/ages. A ps – about men, there seems to be a bulk thing happens around 30. If you won't be able to fit into clothes you had when you were 20, I guess the ring is a similar thing for the hands. Julia Rossi (talk) 12:09, 15 April 2008 (UTC)

White dove?

What species of dove is a pure white dove such as the kind in the Noah's Ark myth of the Bible? 99.245.92.47 (talk) 13:27, 15 April 2008 (UTC)

I'm not aware of a dove species that is normally pure white in the wild. According to this page, Streptopelia risoria has a common mutation that makes it white, and then there's the white homing pigeon, which is a rock dove bred for whiteness and other traits. But I'm also not aware of a translation of Genesis that specifies the color of the dove. --Allen (talk) 18:00, 15 April 2008 (UTC)

Actually, looking at the Wikipedia article for Streptopelia risoria, it doesn't sound like that mutation occurs in the wild either. --Allen (talk) 18:00, 15 April 2008 (UTC)

Possibly you are thinking of the artistic representation of the Holy Ghost such as seen in Piero della Francesca's Baptism of Chist [14]? Any all-white dove would be a white variety of the domestic rock dove (pigeon) [15].--Eriastrum (talk) 21:10, 15 April 2008 (UTC)

Eos

Rather specific question: how rigorously reviewed are articles submitted for the geology newspaper Eos? It says on their website [16] that "Eos is a newspaper, not a research journal" but the Wikipedia article says that its articles are "refereed," and I'm sure you couldn't just send them an article saying the earth is flat and have it printed. So, would any passing person with experience in these matters know the level of "peer-review" (if that term is even applicable) that Eos articles go through?

I'm not interested in submitting an article to them, of course. Just curious--it's a long story. Thanks in advance to anyone who replies.Schmitty120 (talk) 15:02, 15 April 2008 (UTC)

Eos content may or may not have been externally reviewed, at the discretion of the editors. All articles will have been internally reviewed by the editors, several of whom are practicing scientists. In general however, Eos is not intended for the publication of new scientific results (though they don't always adhere to this consistently), it is meant to summarize publications in journals. Dragons flight (talk) 18:14, 15 April 2008 (UTC)

Thanks! I'm still curious though. Maybe this is a better way of phrasing my question: compared to, say, an article being written for the New York Times, how closely will an Eos submission be scrutinized before it is accepted? Will the editors carefully check for flaws in reasoning or questionable interpretations of the data, or no? Would the review process be closer to that of, say, Discover magazine or more like that of Science magazine? Thanks (again) and thanks in advance to whomever responds. (edited once to make my question even more clear) Schmitty120 (talk) 00:57, 16 April 2008 (UTC)

Water in space

Suppose you open a window of the International Space Station, take a cup of room-temperature water and empty it out in space (or more formally: you instantaneously reduce temperature and pressure from room conditions to 3K, 10^-11 Pa). What would happen to the water? Would it instantly freeze and then sublime away, would it instantly boil away, would it first boil a bit, then freeze, then sublime, or any other combination of the above? Thanks, AxelBoldt (talk) 18:09, 15 April 2008 (UTC)

It's not an exact an answer to your question, but DamnInteresting has a excellent article on human exposure to outer space:

In the absence of atmospheric pressure water will spontaneously convert into vapor, which would cause the moisture in a victim's mouth and eyes to quickly boil away. The same effect would cause water in the muscles and soft tissues of the body to evaporate, prompting some parts of the body to swell to twice their usual size after a few moments. This bloating may result in some superficial bruising due to broken capillaries, but it would not be sufficient to break the skin. DamnInteresting

-- MacAddct  1984 ^{(talk &#149; contribs)} 19:35, 15 April 2008 (UTC)

This article might prove helpful: [17] --Prestidigitator (talk) 19:37, 15 April 2008 (UTC)

In Project Mercury when the astronauts dumbed urine into space, it froze into droplets which they referred to as "Constellation Urion." It was shown in National Geographic as such April, 1966, page 548, in the article "Space Rendezvous" by Kenneth Weaver per Collectspace.com[18]. Edison (talk) 23:12, 15 April 2008 (UTC)

Can positronium be liquified

Returning to the question of finding a liquid that can sink styrofoam and pursuing it to the point of pointlessness. Summary so far (to save linking way back up the page):

• Density of styrofoam: 35 to 45 kg/m³
• Density of liquid helium I: 125 kg/m³ (so aint going to do the job, says so in article)
• Density of liquid hydrogen: 70 kg/m³ (oh so close but still not there)

So,

• can positronium be liquified?
• if it can, anyone know how to calculate density?
• if you do, will styrofoam sink in it?

SpinningSpark 21:20, 15 April 2008 (UTC)

Positronium cannot be liquified, because the half-life of the stablest form is on the order of microseconds, so even if you had a kilogram of positronium it would be completely annihilated (i.e. not a single atom remaining) in less than a millisecond.

If you assume some magical way of preventing the positronium from annihilating, then it definitely would liquify at low enough temperatures, and the question of its density is interesting. To do it right you'd have to model it as an interacting Bose liquid, which I don't know how to do. If we assume it has about the same particle density as hydrogen, then its mass density is smaller by the ratio of the masses, which is about a factor of 900, so it would be about 80 g/m^3 (so styrofoam would sink like a rock). —Keenan Pepper 21:46, 15 April 2008 (UTC)

All that decay would produce huge energies, enough to make a plasma. Also it would be chemically reactive like atomic hydrogen, so you would need dipositronium. It should have made a very non dense liquid. Next you had better try a foam to get your density down. It takes a foam to sink a foam. Graeme Bartlett (talk) 21:51, 15 April 2008 (UTC)

Maybe you should try the somewhat longer-lived muonium instead of positronium. A question regarding the 2S state of positronium: "Positronium in the 2S state is metastable having a lifetime of 1.1 μs against annihilation" - that's the lifetime against annihilation, but what's the lifetime against decay to the 1S state? (The reciprocal of the total lifetime is the sum of the reciprocals of the individual lifetimes). Icek (talk) 23:43, 15 April 2008 (UTC)

Causes of Alzheimers

I am looking for the Biological causes of Altzheimers Disease. I have a 10 page research paper due and I cant locate any research articals or anything —Preceding unsigned comment added by Navarro3949 (talk • contribs) 21:42, 15 April 2008 (UTC)

Well I know very little about the disease myself, but you always try the condition's page. Michael Clarke, Esq. (talk) 21:48, 15 April 2008 (UTC)

Minimum operating temperature of CMOS

What is the minimum temperature at which a CMOS circuit will continue to function? That is, if I submerge my laptop in a liquid helium bath, obviously the liquid crystals in the display will freeze and the display will stop working, and the hard drive probably won't be happy, but will the CPU and memory keep working? What about millikelvin temperatures? —Keenan Pepper 22:06, 15 April 2008 (UTC)

Don't know about the physics, but you won't get any manufacturer to guarantee those temperatures. Typical commercial spec devices are rated 0^o to 70^o. Even military spec is only around -55^o to 125^o, and that's operating temperature, not ambient temperature. However, the problems are likely to be mechanical things like the chip breaking away from the substrate due to differential contraction rather than a fundamental physics obstacle. If you wanted to know when (or if) the actual silicon fails, I would imagine it would be quite happy as the temperature went down, the intrinsic resistivity would be going up and the carrier density would be going down, but silicon designers should be able to make heavily doped devices where this would not be a significant problem. That is, until you reach the region where all those funny superconductivity and Cooper pairs stuff starts to happen, which is where my knowledge comes to an end. SpinningSpark 22:36, 15 April 2008 (UTC)

Sense of Smell

I have some flowers that really smell strongly. is the smell caused by the flowers giving off a gas, or is it caused by micro-particulates from the pollen? —Preceding unsigned comment added by Pierhead (talk • contribs) 23:40, 15 April 2008 (UTC)

It's a gas, emitted for the purpose of attracting pollenators. See Flower#Attraction methods. ~Amatulić (talk) 00:16, 16 April 2008 (UTC)

What cant I split an atom with a pair of scissors?

I'm basically asking -why does it take special equipment (or does it?) to split an atom? Is it nature's way of keeping us from blowing ourselves up? There isnt always a bad reaction. Fermilab has been annihilating atoms for years with no ill affects.--Sunburned Baby (talk) 01:37, 16 April 2008 (UTC)

To say it really briefly, it's because the electromagnetic force is much weaker than the nuclear force. Wrad (talk) 01:46, 16 April 2008 (UTC)

[edit conflict]Blades are made of atoms themselves. Try to imagine one spherical atom splitting another and you might get a sense of why it doesn't work. It's actually a lot more complicated than this, because atom-splitting is not a mechanical process... see nuclear fission for details. --Allen (talk) 01:51, 16 April 2008 (UTC)

Gravity and M-Theory

Since gravity is defined as a bending of space-time, why should it be mediated by bosons? Bosons mediate forces, and it doesn't seem that a bending or curvature of something is an actual force.

In M-Theory and string theory, are the strings described composed only of energy? If not, what else are they composed of? Zrs 12 (talk) 01:57, 16 April 2008 (UTC)