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April 19

A few questions about the Japan earthquake...

1. How much radiation is in the sea water?
2. How did the radiation even get out of the nuclear power plant?
3. What types of radioactive material was in the water? (e.g. Was it radioactive metals, gases, or liquids? Did it have gamma rays, alpha rays, or that other kind of rays?)

PLEASE answer. — Preceding unsigned comment added by MickWithoutGlasses (talk • contribs) 00:45, 19 April 2011 (UTC)

Please read our article on the Fukushima I nuclear accidents.--Shantavira|^{feed me} 06:40, 19 April 2011 (UTC)

I thought you asked about the earthquake. The damage to the reactors was caused by the tsunami to the local infrastructure at the reactor sites. The data from the media is all we have available and that data is at best questionable and certainly not reliable. They don't cite the type of detector used the more sensitive the detector the scarier the report, which is of course exactly what they want ... fear. My own Geiger counter gives a result of around 16 counts per minute of background radiation localy. My1 1/2x1 1/2x3" NaI(Tl) Gamma Scintillator which is much more sensitive gives a background reading of over 20000 counts per minute. There is no more radiation but the scintillator is several orders of magnitude more sensitive. While there may be some risk to the inhabitants of Fukushima and its immediate locality there is no appreciable risk to the rest of the world unlike the Chernoble incident which was much more serious and that killed less than 35 people (proved) and they were the workers directly irradiated by the exposed core. Any increases in the global background radiation as a consequence of the Fukushima incident are so small as to be insignificant and are barely measurable. The Granite worktop in your kitchen or the bricks and concrete in your building are more radioactive than anything you will see from fallout from Fukushima.

Gamma's are high energy photons and pass through pretty much anything. Alphas are essentially helium nuclei and cannot penetrate skin or a sheet of paper, Beta are electrons or positrons and can travel only a few feet in air at best and are completely blocked by 3mm of aluminium (aluminum). Radiation is around us everywhere everyday. It is unavoidable and a natural part of the world we live in. Dont Panic !!! — Preceding unsigned comment added by Brian Thwaites (talk • contribs) 02:58, 20 April 2011 (UTC)

"System of Care" health care

Using Google I discovered that System of Care is a health care thing...www.systemofcare.org, which is exactly what I wanted to know...but I was hoping hat Wikipedia could have a page about System of Care. Trust me, Im not the guy to write the Wikipedia page. Thanks and I love Wikipedia! 99.188.102.172 (talk) 02:28, 19 April 2011 (UTC)

One definition given for system of care is "a framework within which health care is provided, comprising health care professionals; recipients, consumers, or patients; energy resources or dynamics; organizational and political contexts or frameworks; and processes or procedures. Current theory recognizes that an analysis of the provision of health care requires knowledge of the systems of care."

It looks like this is probably well covered by our article health care system --- Medical geneticist (talk) 16:05, 19 April 2011 (UTC)

Atomic number and qualities of the element

Perhaps I am misunderstanding this concept completely, but how can adding one proton to an atom completely change the qualities of the element? For example, Hydrogen has one proton and is extremely flammable and explosive while Helium has two protons and is completely inert. I do not understand how adding or subtracting a single proton can change so much about an element when it is seemingly such a small change. It seems very random that an atom with three protons would be a silvery metal while an atom with 29 protons would be a reddish-orange metal, and so on through all the elements. Is there a reason why the qualities of the elements change based on atomic number or is is just a mystery of nature? Any help understanding this would be greatly appreciated, thanks! Zipidiedoda (talk) 02:54, 19 April 2011 (UTC)

My basic understanding: if you change the atomic mass, you're actually going to also change the electron configuration. The things you're talking about (reactivity, etc.) are chemical functions that have to do with the electrons, not the nucleus. Things like color, the way in which the atoms fit together in a lattice, how they bond with other atoms (and release energy, etc.) are chemical reactions that depend on the electrons, not the nucleus. --Mr.98 (talk) 02:59, 19 April 2011 (UTC)

It's true that adding protons requires adding electrons, because the positive charge pulls them in. But what is mysterious is how orbitals work, which is tied to the strange science of quantum mechanics. It turns out that if you have one electron "circling close around" a nucleus, it can readily accept another that is spinning "in the opposite direction". So hydrogen will strive to pair up. Yet throw in a third electron, and there's no way for it to spin around in the same way - it gets stuck in the upper bunk, so to speak, and you have lithium, which is eager to get rid of it wherever it can. Now why can't three or four electrons circle just like two - it's complicated, and hard for me to understand in an intuitive way. It has to do with eigenvalues and the Schroedinger equation and the Pauli exclusion principle and all sorts of nasty math, which is derived not because it seemed like the logical way things ought to happen but because it fit the experimental data. Wnt (talk) 03:08, 19 April 2011 (UTC)

The problem is that the model of electrons existing as little balls orbiting a nucleus in various ways, and physically "spinning" actually doesn't work. The actual model is based a lot more on the wave-like properties of the electrons. There are two perspectives on the actual electron, both of which work perfectly well with the quantum mechanical model, and so we tend to think of them both working simultaneously. First, you can think of an electron as a complex standing wave (like the wave formed on a plucked guitar string as it vibrates). The orbitals around an atom represent harmonics of the fundemental wave. Secondly, you can think of electrons as existing as three-dimensional Probability distribution around the nucleus, indentifying the relative probability of finding a particular electron in a particular location after an abritrarily long time. After you make a scatter graph of all of the possible locations one could find that electron in the space around the nucleus, you basically get the shape of that 3D standing wave I just described above. This probability/wave definition of an electron is what the wavefunction and the Schroedinger equation is all about. The deal with the Pauli exclusion principle is that, if we define an electron in these terms, then we cannot have two electrons that have identical wave functions; two wave functions can only co-exist in the same space if they are orthogonal to each other; that is if the two waves cannot interfere in any way; much as two sine waves at right angles cannot interfere. This is where "electron spin" comes it; this is the property that introduces orthogonality to the wave function. It's not a real "spin" in that there is no little ball rotating on its axis; nor is there two "balls" orbiting in different directions. Its just a (somewhat arbitrary) name given to the part of the wavefunction that allows two electrons to coexist in the same physical space. --Jayron32 04:15, 19 April 2011 (UTC)

Hmmm. You say electron spin isn't really spin, but... when electron spin flips (relative to one spatial dimension), it is transmitted away by means of a photon with an angular momentum of hbar. The spin of this photon is a real thing, isn't it? A circular polarization that can be measured by passing it through filters. Am I wrong? Wnt (talk) 05:38, 19 April 2011 (UTC)

Sort of. Particle spin in physics is a real physical property of particles; it's just not actually spin. When you tease the property out of the particles, it behaves like angular momentum, and it has directionality (the terms "spin up" and "spin down" are real aspects of particle spin, relative to the z-axis). However, with point particles, its not clear how such a particle can physically spin. The name is an artifact of treating electrons like little balls; this is explained well at Spin_(physics)#Elementary_particles. So, it's called spin because mathematically it behaves like classical angular momentum, but there's nothing to spin in fundemental particles, since they have no internal structure to spin about. Spin is likely more related to some sort of fundemental directionality; the other aspects of a particle's fundemental properties (like charge and mass) make no directional distinction, spin uniquely does. It is through spin that we can establish a non-arbitrary set of axis to define the regions around an atom, for example. Still, though it is tempting, one must resist using this property of spin to treat electrons like little balls; they clearly don't behave that way. After all, quarks aren't really colored, and fundemental particles don't really taste like anything. --Jayron32 05:58, 19 April 2011 (UTC)

No—color has nothing to do with color, and flavor has nothing to do with flavor, but spin really is spin. Just as you can develop a theory of instantaneous velocity by taking the limit of the velocity over successively smaller time intervals, so you can develop a theory of "angular momentum at a point" by taking a limit of successively smaller spinning objects. The theory you get when you do that is the theory of particle spin. That doesn't mean that particles are spinning points. They might be very small spinning objects, or they might be Kerr–Newman black holes, or something else entirely. It's a mistake to take any aspect of the standard model of particle physics too literally. All we really know is that particles behave like they're spinning. -- BenRG (talk) 07:01, 19 April 2011 (UTC)

When I look at the figures in circularly polarized light, it certainly looks like something is really spinning. A photon should look like a brief segment of such a wave, trailing off at either end, moving forward like a corkscrew. Now I am still slightly hazy on the spin number of light - apparently it is hbar in two dimensions, adding up to sqrt(2) hbar - but my impression is that the spin of the light in the dimension of its travel should match this classically perceptible rotation. Question: can you actually look at the E and B fields of a circularly polarized photon and derive hbar as the angular momentum of the energy it carries?? Wnt (talk) 07:40, 19 April 2011 (UTC)

The deal with particle spin, which I guess by BenRGs reasoning is that it is OK to call it a spin (by a certain perspective) is that it doesn't interact with other, macroscopic angular momenta, outside of the "particle spin" mode. Think about a molecule like triplet oxygen. Triplet oxygen has "particle spin". This is because, as a diradical, it has unpaired electrons. This particle spin generates a magnetic field (as all spinning charges, point particle or macroscopic) should. This creates the property of paramagnetism in groundstate dioxygen. However, the oxygen molecule itself also has a rotational axis (two in fact) perpendicular to the bonding axis of the molecule. Being a non-spherical molecule, that means it has an axis about which it can rotate. However, I am not aware of any way that the particle spin has any effect on the rotation of the molecule; I am willing to accept that I am wrong on this, but it is my understanding that the "particle spin" which accounts for dioxygen's paramagnetic nature does not increase the molecule's rotational energy, which is pretty much exactly what spin is. If we take the situation to a classical analogy; we could look at dioxygen like a helicopter. The existance of angular momentum of the helicopter blades tends to introduce a torque into the helicopter, that's why there needs to be some counteracting force in the form of some stabilizing counterrotation of some sort. Likewise, if the "spin" of oxygen's electrons were the same sort of thing, it would only stand to reason that this would cause the molecule itself to rotate. The same should happen in ANY radical molecule, such as Nitrogen dioxide. I am not aware of such an effect, though I am open to an explanation of either a) why my reasoning is wrong or b) where such an effect actually occurs. --Jayron32 13:24, 19 April 2011 (UTC)

I'm really on the wrong side of the bar here, but to quote [1], "The energy of a molecule can be approximated as the sum of the contributions from its different modes of motion (translation, rotation, and vibration), the distribution of electrons, and the electronic and nuclear spin. Given that the energy is the sum of independent contributions, ... the partition function is a product of contributions: q = q^T q^R q^V q^E q^S where T denotes translation, R rotation, V vibration, E the electronic contribution, and S the spin contribution. The contribution from electronic spin is important in atoms or molecules containing unpaired electrons. For example... the Cs atom, which has one unpaired electron ... contributes a factor of two to the molecular partition function."

Now to what degree I understand it, this means that the amount of entropy, at least, is increased by the spin (it doesn't really increase the molecule's energy in the sense that the spin can't drop to zero, though pairing spins is welcomed in chemical bonding). The molecules with electron spins are free to move energy back and forth between those and rotational spins, and since angular momentum is always conserved I assume that means that the direction of the electron vs. molecular spin matters. So I really would think of electron spin as a "real" spin, contributing to the overall motions going on within the molecule. Wnt (talk) 19:38, 19 April 2011 (UTC)

That quantum spin can couple arbitrarily to other quantum numbers is unsurprising. This sort of thing happens between all of those various contributions. More telling in your description is that the rotation of the molecule and the spin of the molecule are treated differently; that is the quantum rotation (that of the entire molecule spinning) is an independent value from the quantum spin value (that calculating by summing all of the individual electron spins). To me this tells me that there's no special physical relationship between those energies, over that one would expect from any coupled modes of energy, such as vibration and electronic. In other words, spin and rotation are unique properties, and though each is classified in terms of "angular momentum" they actually measure different things about a molecules. --Jayron32 19:54, 19 April 2011 (UTC)

Well of course the rotation and spin should be different - in rotation the two nuclei are moving end over end, after all. Though it would be interesting to consider the rotational mode of a helium atom, or more to the point, monatomic hydrogen! What I did find is the spin isomers of hydrogen article which says that only para hydrogen can fall into the lowest energy symmetrical rotation state. Wnt (talk) 22:40, 19 April 2011 (UTC)

Basic answer (as oultined above) is that chemical properties are determined by electrons, not by nuclei and nuclear processes. So it is not adding or subtracting protons (or neutrons) that changes the chemical behaviour of an element - it is the associated addition or subtraction of electrons. Example - sodium chloride has chemical properties very different from either sodium or chlorine, yet its atomic nuclei are standard sodium and chlorine nuclei; its chemical properties are due to the transfer of electrons and the resulting creation of ionic bonds. Gandalf61 (talk) 11:03, 19 April 2011 (UTC)

Chemical properties are primarily determined by electrons (especially in covalent compounds), but those electrons are certainly affected by the protons (especially in ionic compounds). For example, they are what actually causes the ionic charge once the electrons have been added or subtracted to get a closed shell. "Why is it +2?" Because it has 2 more protons than electrons. Why two? Because that's how many electrons it lost to get to a stable electronic configuration. But why did it have "two more than a stable electronic configuration" when it was neutral? Because that's how many protons it had. And isotope effects are real chemical-reactivity differences due solely to mass not atomic number or charge. DMacks (talk) 12:50, 19 April 2011 (UTC)

Why only 92

Since we know of only 92 naturally occuring elements, the other 17 transuranics (maybe more now) being man made, and since we know about the enormous pressures, temperatures and densities that exist in many types of stars, it seems inconceivable that mother cosmos has not been able to make any elements with a greater atomic mass than U238. questions. (1) Has there ever been any observed indications of natural elements heavier than U238

(2) If the answer to (1)is no, then does this indicate some naturally limiting factor. If yes, then what is it.

(3) If "no" again then what might that limiting factor be.Phalcor (talk) 03:02, 19 April 2011 (UTC)

Neptunium (239, I assume) is actually produced in trace amounts in natural uranium ores. (On the other hand, technetium was synthesized). See nuclear shell model - nay, rather Magic number (physics) - for a diagram of how the largest known nuclear shell marks the end of the stable sequence at bismuth. Some believe that an island of stability of super heavy elements exists, but the number of neutrons for the best isotopes keeps going up, making it very difficult even for supernovae to make them out of smaller nuclei with fewer neutrons. Wnt (talk) 03:13, 19 April 2011 (UTC)

(edit conflict) (1): Yes, there have been observed natural elements heavier than U238: Plutonium is the heaviest Primordial nuclide, and is found in extremely small quantities in nature left over from the Earth's formation. It has also been formed more recently in the Natural nuclear fission reactor of Gabon, though again, has almost completely decayed by now. Other, heavier elements were (and are) created in stars, but are not found on Earth only because they've decayed away in the 4.5 billion years since Earth's formation. Buddy431 (talk) 03:16, 19 April 2011 (UTC)

But neptunium has amu of237.0482 less than U238 with amu 238.03 and plutonium exists in nature only as an isotope of U238. the Element plutonium is greater amu 244.0 but is man made as you said at gabon and other places and was used in (fat boy) over Nagasaki. If other heavier elements have existed and decayed then there would be a non-radioactive element left in it's place, such as uranium to lead. If I understand it correctly they do not simply disappesr. correct my if I'm wrong but all the elements 93 to 109 are all man made I'm asking about natural elements above 92 —Preceding unsigned comment added by 190.56.115.96 (talk) 04:32, 19 April 2011 (UTC)

Plutonium-244 is created by natural processes, and has an atomic number greater than 92. --Jayron32 04:40, 19 April 2011 (UTC)

(edit conflict with Jayron) Stars produce many elements above 92, but uranium is the heaviest element that decays slowly enough that it's still here on Earth after 4.5 billion years. The reason heavier elements decay faster is well answered by Wnt. In short, there's nothing special about U-238 is terms of being produced by nature, it's the decay times that determine whether it still occurs naturally on Earth. U-238 decays slowly enough that there's still a lot of it after 4 billion years. Pu-244 decays slowly enough that there's a tiny amount of it after 4 billion years. Buddy431 (talk) 04:44, 19 April 2011 (UTC)

Thanks guys I just checked out "island of stability" Guess I should have done that earlier Huh. Boy do I feel updated, or dated or something. Yeh I'm gonna have to throw some books away and graduate to the computor.190.56.14.159 (talk) 05:32, 19 April 2011 (UTC)

is there a formula from wavelength in nanometres to RGB?

Suppose I have a sharp band of 632.4 nm light. What RGB value should I use to represent it? John Riemann Soong (talk) 06:03, 19 April 2011 (UTC)

Depends how accurate you need it, if it's just rough, my guess is about 255,50,0. I'm seeing a few conflicting sources, some saying it's roughly red, some saying it's more orange. Vespine (talk) 06:38, 19 April 2011 (UTC)

Actually just found a site that does it, it says 255, 70, 0.. Hey! My guess was pretty good:) lol. Vespine (talk) 06:41, 19 April 2011 (UTC)

Because the RGB receptors in the retina don't match the RGB mapping of your screen (they actually use a different system, and vary from person to person), you will never get a "perfect match" for everyone. Dbfirs 07:14, 19 April 2011 (UTC)

Human vision is not an RGB system. There are three color receptors, but they are not simple red, green, and blue detectors.--Srleffler (talk) 17:22, 20 April 2011 (UTC)

I think that applet is somewhat inaccurate, as it claims to use this code, which links to this page, which displays this chromaticity diagram generated using the algorithm, which is rather different from this chromaticity diagram, which I trust more. You could use an eyedropper tool on the latter diagram to get a better answer. There is actually no correct sRGB value for any monochromatic color; you have to desaturate the color (mix it with white) to get something in the sRGB range. And color perception does vary somewhat from person to person. -- BenRG (talk) 07:34, 19 April 2011 (UTC)

I agree with previous replies; there is no single "correct" relationship. A lot of thought has been put into finding good approximations, see e.g. this article. (I had once seen a nicer one with the pictures directly in the article, but I can't find that one just now.) — Sebastian 17:56, 19 April 2011 (UTC)

Electrodynamics

what is the physical significance of displacement current? — Preceding unsigned comment added by Karan khajuria (talk • contribs) 11:03, 19 April 2011 (UTC)

It produces a magnetic field just like an actual alternating current would produce. Dauto (talk) 15:17, 19 April 2011 (UTC)

But its not a real current in that it cannot be measured directly.--2.98.149.24 (talk) 21:35, 20 April 2011 (UTC)

Chickens in a container

I recently heard something on TV which has me puzzled. It was talking about a sealed shipping container containing chickens on a weighbridge. The show's presenter said that if you could get all the chickens to fly into the air at the same monent, it would not affect the measured weight of the container on the weighbridge. I sometimes fleetingly think I understand it, but can anyone explain, please? Si1965 (talk) 12:19, 19 April 2011 (UTC)

Mythbusters tackled this one, but I can't remember what they found. HiLo48 (talk) 12:27, 19 April 2011 (UTC)

See here. --Mr.98 (talk) 17:27, 19 April 2011 (UTC)

Flight works by increasing air pressure beneath the bird (and decreasing it above), which spreads out as a roughly cone-shaped region above and below it. This applies forces to the floor and roof of the container which add up to the weight of the birds. So, the overall weight of the container doesn't change. Now, if it was open at the top and bottom (say with gratings), then the air pressure would go down below the container, and apply to whatever was below it. If the bridge also had a grating form, then the air pressure change would continue to spread down and out, eventually being supported by the ground. The same is true, in reverse, for the decrease in air pressure above the birds. So, there could be a tiny difference when the birds were all in flight. However, note that not very many flying chicken could fit in the container, as collisions and the air pressure from those birds flying near the roof would both force lower chickens to fall back down. StuRat (talk) 12:44, 19 April 2011 (UTC)

Interesting. I could find no article dealing with chickens flying in shipping containers. Your answer may well be definitive Sturat, but it occurs to me that the kinetic energy transfered to the air by the wings would be completely or mostly used up by the work of compressing the air locally beneath the wing which would then completely decompressed in all directions, thereby the weight of the chicken would not be transfered to the bottom of the container.190.148.134.75 (talk) 14:33, 19 April 2011 (UTC)

Mythbusters used pigeons. They fly better than chickens. HiLo48 (talk) 17:34, 19 April 2011 (UTC)

The force does dissipate in all directions, but the downward component of the force eventually works on the ground.

Perhaps it would help to imagine something bigger and more powerful. Imagine a helicopter in a box. Clearly, the helicopter is pushing down on the bottom of the box.

The higher the helicopter is, the harder it is to notice that downward force because it's spread out over a wider area. APL (talk) 14:53, 19 April 2011 (UTC)

Unless said helicopter is in a box where the air disturbances can not dissipate. Googlemeister (talk) 15:04, 19 April 2011 (UTC)

Right. APL (talk) 15:10, 19 April 2011 (UTC)

In any case, chickens don't really fly all that well. The longest I ever saw one stay in the air was less then 10 seconds. Googlemeister (talk) 16:02, 19 April 2011 (UTC)

Also discussed in episode 8 of QI (H series).--Shantavira|^{feed me} 16:39, 19 April 2011 (UTC)

How sealed? If it is air tight, there should be literally zero mass difference. You are not weighing the bottom of the container, you're weighing the whole container unit, air, chickens, and all. --Mr.98 (talk) 17:27, 19 April 2011 (UTC)

Best of all, if it's air tight the chickens eventually stop moving so you can get an accurate measurement on your scale. APL (talk) 18:46, 19 April 2011 (UTC)

This is true - until the chickens stop moving up and down, the weight on the scale will keep changing. It will only average the same as when they're not flying. Wnt (talk) 19:14, 19 April 2011 (UTC)

Having sex after working out

Since body testosterone plays an important part in muscle growth, does having sex shortly after exercising intensely improve the results of the work-out? I am assuming the person in question assumes a more passive role in sex, in order to favour recuperation. Leptictidium (mt) 13:20, 19 April 2011 (UTC)

Assuming there is an effect, it is not clear to me why you would need to do this "shortly after exercising". What is known is that exercising an hour or so after the main intense exercise does help recuperation. Count Iblis (talk) 16:47, 19 April 2011 (UTC)

Excessive caffeine and hair loss

Is there any correlation between the two? I read that caffeine can cause numerous nutritional deficiencies (iron, vitamin b, etc) which can lead to hair loss; or that it could lead to an increase of DHT, which in turn causes hair to fall off at a faster rate. However, I didn't find any reliable sources concerning this.

24.202.44.252 (talk) 13:46, 19 April 2011 (UTC)

You are probably stretching things too far. A -> B and B -> C both being true in different studies does not always equate to A --> C in real life. There are so many different variables involved that you can't always put 2 and 2 together. This article suggests that caffeine might actually stimulate hair follicle growth at least in vitro. However, a little bit of personal WP:OR suggests that this is not working in vivo. Perhaps I should be using a caffeine shampoo for better effect. --- Medical geneticist (talk) 15:57, 19 April 2011 (UTC)

If someone is losing his hair due to genetic causes, I doubt coffee will change the picture. 212.169.181.129 (talk) 22:09, 19 April 2011 (UTC)

Caffeine is a Featured Article -- it's a pretty good source for reliable information. Looie496 (talk) 02:21, 20 April 2011 (UTC)

vitamins

I heard somewhere that a lot of the benefits of vitamin pills are counteracted by the body not absorbing the vitamins well. Is this because all the vitamins show up in a large bolus? In that case, wouldn't it make sense to divide the vitamins into say 4 parts and take one part every 6 hours or so?

Googlemeister (talk) 16:01, 19 April 2011 (UTC)

The bolus isn't really the issue, normally. There are many reasons why they may not be absorbed properly:

1) Some are fat soluble, so need to be taken when eating fats.

2) Some can't be absorbed in the presence of certain other foods.

3) Sometimes they give you a different form of the vitamin than you get from food.

4) And, of course, you may not have a deficiency in the first place.

One case where the bolus does seem to be a problem is when they give dialysis patients a week's worth of iron in a single ferritin injection. This causes local problems in the area of the injection. StuRat (talk) 16:25, 19 April 2011 (UTC)

materials treatment

Could waste materials be heated up to a high enough temperature leaving all the elements of the waste by themselves then could these be filtered by their density? —Preceding unsigned comment added by 82.38.96.241 (talk) 16:12, 19 April 2011 (UTC)

Possibly, but that would take a huge amount of energy. StuRat (talk) 16:31, 19 April 2011 (UTC)

At microscopic/atomic levels, this is (partly) how Mass spectrometry works, but it is difficult to envisage this being scaled up to macroscopic quantities economically. {The poster formerly known as 87.81.230.195} 90.197.66.111 (talk) 16:47, 19 April 2011 (UTC)

Methods based on this principle might be used extra terrestrially at some point in the future (possible by the Chinese at the speed they are advancing). http://www.permanent.com/i-distil.htm --Aspro (talk) 18:54, 19 April 2011 (UTC)

Great website aspro —Preceding unsigned comment added by 82.38.96.241 (talk) 12:47, 20 April 2011 (UTC)

Yes, it exists, it's called: Plasma arc waste disposal. Ariel. (talk) 01:26, 21 April 2011 (UTC)

Absolute

I've been fixing the links to the disambiguation page absolute. I can't seem to find a Wikipedia article about absolute as the opposite concept of relative in a scientific context. Does anyone know of such an article? Thanks, P. D. Cook ^{Talk to me!} 17:39, 19 April 2011 (UTC)

There's Absolute time and space. Does that help? --Tango (talk) 18:11, 19 April 2011 (UTC)

There's also Absolute temperature (redirecting to Thermodynamic temperature), but I suspect that these are too specific for the OP. I'd say that is because "absolute" is rather a case for Wiktionary; it's hard to imagine a whole Wikipedia article about so general a term. — Sebastian 18:36, 19 April 2011 (UTC)

Well the concept of an absolute measurement (versus a relative one) comes up many times in math and science (temperature scales, coordinate systems, scoring systems, etc.), so I could see there being an article about it or maybe a section in a broader one. I had been considering just linking the articles in question to Wiktionary, and now that you mention it as well, I might do that. Thanks for your input. P. D. Cook ^{Talk to me!} 19:15, 19 April 2011 (UTC)

You are raising a good idea, maybe it would make sense as a subsection of Measurement. Still, at least for me, the absolute/relative dichotomy often isn't so clear cut. Take the height of Mount Everest. You'd probably say it's ~9km absolute, and some lesser value relative to the base camp. However, one could just as well argue that 9km is the value relative to sea level, and measure the absolute value from the center of the earth. I see this as a mere situational convention, rather than an underlying physical dichotomy. — Sebastian 21:34, 19 April 2011 (UTC)

Testosterone Levels

In a recent article in the New York Observer, the author writes:

"Indeed, it's no longer so easy to be male. If you're a frog, this is literally true—modern environmental toxins can actually turn you into a female. If you're a human, they've merely halved your sperm count since the 1940s and zapped 15 percent of your testosterone since the 1980s."

We'll let the frogs be for now – are the claims he makes about men really scientifically documented? Wouldn't a 15% change in a testosterone levels have a profound effect on anyone? And, what types of environmental toxins, if any, could alter testosterone levels like this?

Alfonse Stompanato (talk) 18:37, 19 April 2011 (UTC)

Sounds very dubious. As usual, the impetus is on the originator of the claim to provide evidence; it's very hard to publish a scholarly article that provides counter-evidence to every inane claim ever made. Do you need help finding epidemiological studies of hormone levels? Nimur (talk) 18:49, 19 April 2011 (UTC)

The lower sperm count may have more to do with modern fashions, where tight pants overheat the testicles. Scotsmen had the right idea with kilts, apparently. StuRat (talk) 18:52, 19 April 2011 (UTC)

The article on Endocrine disruptors might interest you.--Aspro (talk) 19:08, 19 April 2011 (UTC)

FPGAs in space applications

Where can I find extensive information about that topic? Thanks. --Belchman (talk) 19:18, 19 April 2011 (UTC)

I previously worked on these: Rad Hard FPGAs from Actel; but I think Actel has seen better days. I'm not sure if that datasheet is up to date. You probably cannot find "extensive" information about them, because they are subject to export control and other regulation. Nimur (talk) 21:37, 19 April 2011 (UTC)

That's useful, thanks. --Belchman (talk) 22:32, 19 April 2011 (UTC)

ChemDraw diagrams in articles

how can I place into body article chemical structures, like polysaccharides, written by Chemdraw programBermanel (talk) 19:53, 19 April 2011 (UTC)

You have to save the ChemDraw drawing as a graphics file format (png, gif, jpeg, etc.) rather than as a ChemDraw document (cdx, etc.). Use the ACS template when making your diagram, and save the image as a PNG format with a resolution-option of 720dpi. Then, upload that image file. An image is its own item on wikipedia, not "a component of another page". Finally, edit the page where you want the image to appear and enter the wiki-code for it. Wikipedia:Creation and usage of media files has lots of specific details about how to upload files and insert them in pages. WT:CHEMISTRY is a place to discuss chemistry issues related to wikipedia articles (formatting and style, etc). DMacks (talk) 20:20, 19 April 2011 (UTC)

Actually for something like that SVG will almost definitely be preferred if they render properly. If you only create a PNG it's likely you're creating future work for someone to recreate the image in the future. According to Wikipedia:Manual of Style (chemistry)/Structure drawing#Generating SVG files ChemDraw 12 should be able to generate SVG files. Nil Einne (talk) 10:33, 21 April 2011 (UTC)

Until the very latest release and highest-end product, I don't think the ChemDraw suite supports SVG export:( Of more concern, XfD has extensive trail of SVG images that are "correct" but render incorrectly on WP. Not sure if ChemDraw does them viably, or if they require extensive post-processing to render corectly. It's clearly a better format in many respects and may be the way forward, but CHEMMOS does not state a preference either way at this time. DMacks (talk) 14:18, 21 April 2011 (UTC)

Um the page I linked to earlier is part of the MOS and says "SVG files are preferred, because they are smaller in filesize, can generate high quality images for printing and are easier to translate if text is added to mechanism." In any case, if CHEMMOS didn't say anything it wouldn't overide the general wikipedia (let alone commons) consensus SVG is preferred for anything suitable for vectors images (provided there's no reason it can't be used like the content doesn't render properly which I earlier specified as an exception well aware it can sometimes be a problem). The plenty of images I'm guessing including some chemical structures tagged for replacement atest to that hence I think a good reason to encourage people to start with SVG in the first place, and only use PNG if they can't (note I didn't ask the OP to jump thru hoops to try and make SVG, simply pointed SVG is prefered and any PNGs are likely to require replacement in the future and ChemDraw 12 from our own MOS is allegedly able to generate SVG). BTW the MOS I quoted earlier does say ChemDraw 12 hence why I specified that but doesn't say anything about needing a specific variant/highest-end version hence why I didn't specify that, if it's deficient in this regard it should be rectified. P.S. I'm aware the smaller in file size isn't always true, but I didn't add that text and this isn't the place for such discussion. Nil Einne (talk) 23:27, 21 April 2011 (UTC)

Last I looked (and it has been a year or so), svg did not appear to be present in the student-/entry-level chemdraw packages (vs full chemoffice or chembiodraw suites) and/or only on Windows platforms. The page you linked does agree with windows-only, and the only hits for I'm finding now via google for "svg" on cambridgesoft.com talk about the full suites. It may well be there, I'm just not seeing it:( I'd love to see svg widely used, I hate that it involves hoops and poor results when it should be no harder than other formats and give good results (the "may not be rendered correctly on Wikipedia" note on the same MOS page you link). DMacks (talk) 01:21, 22 April 2011 (UTC)

I see Wikipedia advocates .svg, but I'm not clear on why. There's one good freeware program to draw the files, Inkscape, but anyone using Inkscape is frowned upon - in part because svg files often don't look the same in Inkscape as on your browser! (Those isotope and decay maps we were looking at recently, for example) All the svg policy means is that most people can't/shouldn't bother trying to make images. Oh, and if we ever do get good tools for making svgs, shouldn't they include something that can automagically convert pixelated images into svg images assuming that what look to the eye like straight lines are meant to be straight and so forth? Wnt (talk) 06:59, 22 April 2011 (UTC)

Windward Islands and trade winds

Trade winds (yellow arrows) come from the northeast in most places, including at the Antilles.

There is a great comparison table at Windward Islands#Terminology, which shows that (in English) the "Windward Islands" lie to the south and southwest of the "Leeward Islands". How can this be, given that the trade winds come from the northeast? — Sebastian 21:23, 19 April 2011 (UTC)

The Windward Islands lie to the southeast of the Leeward Islands. See File:LesserAntillesIslands.png. Most ships probably approached the Carribean from the coast of South America, moving northwestward. The first islands they would hit in this path would be the Windward Islands, exactly as the name implies. --Jayron32 04:53, 20 April 2011 (UTC)

Clearly, Aruba lies southwest of any of the Leeward islands. Or are you saying our table at Windward Islands#Terminology is wrong? If we leave out the portion from Isla de Margarita to Aruba, that would take away some of the worst contradictions.

Still, even then the name doesn't fit the wind. Since the remaining islands are not arranged in a straight line, it's a bit moot to quibble over whether they are arranged in a south-north fashion or in a southeast-northwest one. Instead, let's actually measure concrete angles:

• First, let's look at the wind direction. The yellow arrow in the above map indicating the trade wind pointing at Guadeloupe, has an angle of 255°. (We probably have a measurement error of about 10° for this and the other measurements.)
• Next, let's look at the course from Dominica to Martinique, right at the border between "Windward" and "Leeward" islands. That is about 155°. If it were 165°, it would be exactly perpendicular to the wind. It's a bit less than that, so that one can say that Martinique is a little bit upwind from Dominica, but that difference is less than the size of the islands; the downwind side of Martinique is still upwind of the upwind side of Dominica.
• Now let's look at the other extreme, the furthest downwind of each island chain: The course from St Croix to Trinidad is about 160°, which is also about at a right angle to the wind.
• Lastly, let's look at the most upwind islands: Barbuda and Barbados. There, too, the angle is about perpendicular to the wind.

I have to conclude that the island groups are not up- and downwind from each other, but almost exactly abreast. How could Britannia, who ruled the waves, get the direction of the wind wrong by 90°? — Sebastian 07:38, 20 April 2011 (UTC), corrected 08:02, 20 April 2011 (UTC)

The term Leeward Antilles may be of some interest to this discussion, vis-a-vis Aruba; the specific use of "windward" vs. "leeward" in relevence to the islands off the coast of Venuzuela is somewhat in flux; so lets throw those out for the purpose of the discussion. Secondly, the terms "windward" and "leeward" apply not merely to the wind, but how the wind carries your ship to get there. The wind gets you to the Windward islands first on the standard trip from Europe, hence the name. Thirdly, lets look at your supposition: You claim that terms invented by people who had a practical, working, everyday knowledge of seafaring are wrong at their own job, and that you can determine this by looking at a tiny, low-resolution, amateur-created map of the entire world with some yellow arrows on it, yellow arrows of no confirmed reliability, and which are on a map that gives no indication of how literally and acurately we are supposed to understand their direction, and using a protractor on the yellow arrows of dubious reliability and applicability, claim that the entirety of the British Navy, whose job description is largely "know how to get a boat where you want it to do" didn't know how to get their boats where they wanted them to go? Really? --Jayron32 12:05, 20 April 2011 (UTC)

We seem to agree on most of the details. The Leeward Antilles are just the portion from Isla de Margarita to Aruba which I mentioned above, and we agree to throw them out for now. We agree that the British were very good sailors and that it is unlikely that they would choose a name that doesn't fit reality. We also agree that there is some measurement error, but I see no reason to assume an error of 90°. Trade winds are known to have a northeasterly direction, and they're pretty reliable; you can't twist them to become southeast winds just to fit the name.

Where we differ is in the conclusions we draw. You seem to be saying: "Because the British Navy said so, all other evidence must be dismissed." I, OTOH, say: "This is odd. Let's investigate this further. Let's ask at RD/S, there are probably people who like this sort of riddle."

So now, let's investigate this further. You suggest looking at how the wind carries your ship to get there. That is an interesting suggestion which hadn't occurred to me; If I may paraphrase, you translate "windward" as "that which you reach first". You go on to state that "The wind gets you to the Windward islands first". At first glance, the opposite seems to be true, as the Leeward Islands are closer to Britain. (Moreover, the wind direction should not make a difference in this case, because the general direction of the wind is favorable, and ships don't just drift like leaves in the wind, but have great liberty as to the course. In fact, for square rigged ships "best speed is made in a quartering wind"[2].) Well, maybe we need to look at how the current carries your ship to get there. (The Antilles Current, to be exact.) Alas, at about 0.7 kn (about 1/20 of the ship's speed) and with a direction similar to that of the wind, the effect should be too small to counter the bigger distance.[3].

But this gives me another idea: Maybe it is wrong to assume that ships were coming from Britain. Britain was engaged in the triangular trade, so the ships that came from Africa would reach the southeast before the northwest. Could that explain why the English nomenclature is different from the German, as Germans did not engage in the triangular trade, and would therefore come directly from Europe? This sounds like a bold hypothesis; what do other editors think? — Sebastian 06:45, 21 April 2011 (UTC)

As my last question is not a science question, but rather a history question, I posted it at WP:RD/H. Please post any history related replies there. — Sebastian 07:09, 21 April 2011 (UTC)

It appears this was never answered and the paragraphs describing the terminology on each island group's pages is as confusing as ever. We need to answer two very basic questions 1.) Were this islands named in relation to one another or from the relation of England to both groups of islands (it seems it can't be the latter, as it doesn't make sense), and 2.) exactly which way does the wind blow in relation to both sets of island groups? This has been incredibly hard for me to nail down. I literally found a source yesterday describing the winds coming from "the south" which is completely different from most sources saying that the winds come from the northeast and southeast (basically meeting at the islands). So, were most English ships (or at least the ships that gave these islands their names) coming from the southeast (Africa) or the northeast (Europe)? For me, if the winds are coming from the south and/or southeast as were the ships, then the names of the island makes since to me as the leewards would be downwind of the windwards. The direction would be, then, ships traveling the curve from the south to the northwest. If the winds and ships are coming from Europe, I guess it still makes sense, as I guess you'd eventually hit where the winds collide so you'd go from sailing with the windward (leeward thus the leeward islands would be landed upon first) to be sailing into the wind (windward) to hit up the islands to the south/southeast?

I guess what I'm saying is that I want to see some detailed wind maps, because that makes all of the difference in the naming of the island groups. --Criticalthinker (talk) 11:41, 14 September 2017 (UTC)

IBM Watson's size in 10 years.

According to Moore's Law, how small would Watson get by his 10th anniversary? Would his entire hardware finally fit behind a game show podium? What would be his estimated dimensions? --70.179.169.115 (talk) 21:30, 19 April 2011 (UTC)

You're making a few strong assertions: that Moore's law applies to Watson's technology (which is dubious); and that Moore's law implies volumetric scaling of the computer-system (when in fact Moore's law was originally an empirical observation of a trend in transistor feature size). We can't make a conclusive speculation about what future computer architectures and parameters will be like, but you may be interested to read about emerging technologies at IBM AlphaWorks, the official distribution source for IBM research and technology. Nimur (talk) 21:36, 19 April 2011 (UTC)

Our article says Watson runs at about 80 TeraFLOPS, which puts it 94th on the most recent TOP500 List. The number 94 supercomputer on the list 10 years ago was 208 GigaFLOPS. These days, that's slightly faster than a top-end PC (I'm not citing a reference for that because I can't find a good one, but I have found several bad ones that all agree, so I'm fairly confident about it!). If you wanted to, you could easily get 208 GigaFLOPS in a game show podium. So, if we assume past trends continue into the future (they've continued for a while now, so it's a reasonable assumption) there should be no difficulty getting Watson into a game show podium in 10 years. (And that's just considering hardware - if you allow for software improvements (it's the software that is impressive with Watson) then it should be able to get it that small significantly quicker. I've also ignored memory requirements - I don't know what proportion of Watson's volume is memory.) --Tango (talk) 22:03, 19 April 2011 (UTC)

It's very likely that Watson doesn't use floating-point arithmetic in its operation, given its purpose is to answer questions given in a natural language. Therefore, I don't think it's possible to work out when Watson can fit inside a game show podium by estimating when a PC can match or exceed Watson's LINPACK score. I think a better approach would be to look at what hardware attributes enable Watson (my guess is memory capacity, memory bandwidth, and integer performance) and when a PC or podium-sized computer is expected to match or exceed Watson in these areas. Rilak (talk) 06:09, 20 April 2011 (UTC)

Whatever metric you use, you see the same basic trends. I think the fact that I neglected improvements in software will have a greater impact than using floating-point rather than integers. --Tango (talk) 19:40, 20 April 2011 (UTC)

If cars followed Moore's Law from the 1925 Model T

At 6.9 HP per liter for a 1925 Model T, if cars started following Moore's Law from that year, how many HP would an economy car's 1.0 liter engine contain? What devices have that much power today, and what would that kind of power do?

Or if we only needed 1,000 HP, how big would the engine need to be? What other object(s) would it then be the size of? --70.179.169.115 (talk) 21:30, 19 April 2011 (UTC)

Well, if HP per liter doubled every two years, starting in 1925, the current value would be 2⁴² times the 1925 value.

That 1.0 liter engine would output more power than is consumed by every piece of equipment on earth. APL (talk) 21:39, 19 April 2011 (UTC)

Wow. Okay then. So if we decided to leave more room for passengers and cargo by shrinking engines, how small would an engine need to be to output 1,000 horsepower if it followed Moore's Law like so? (To give you a starting reference point, 1,000 HPs would need to fit in a 145-liter engine in 1925, strictly calculating from the Model T's stats.) --70.179.169.115 (talk) 22:31, 19 April 2011 (UTC)

Automobile locomotion is not governed by the same physical principles as microelectronics; so your attempt to apply Moore's Law to engine scalability is flawed. As the joke goes, "if GM were like Microsoft..." Nimur (talk) 22:43, 19 April 2011 (UTC)

Hence the "If" in the question. StuRat (talk) 00:28, 20 April 2011 (UTC)

Yes, and to be clear, Moore's 'law' isn't any sort of physical law, just a descriptive pattern for the past few decades. No reasonable scientist thinks it will hold true indefinitely. Even our article says this pattern is only "expected to continue until 2015 or 2020." SemanticMantis (talk) 00:38, 20 April 2011 (UTC)

Actually, the article says "...until 2015 or 2020 or later" (emphasis mine). That sentence is referring to the earliest that Moore's law might end, not the latest. And Moore's law has always been something that's unclear as to whether it'll be possible to sustain for more than about another ten years. Gordon Moore's original 1965 paper just said that the exponential increase was expected to continue "for at least ten years". Moore's law can't be sustained forever, but it won't be possible to predict the timing of the law's demise much in advance. Red Act (talk) 04:48, 20 April 2011 (UTC)

Also note that the article's reference for the 2015 to 2020 dates refers to a news article that was published six years ago, so the referenced article was looking 10 to 15 years ahead with those dates, not 4 to 9 years ahead. And the cited article was actually only predicting that that will be about the time range when the use of silicon for computing will start being replaced by one or more of a large number of newer technologies that are being worked on, not when the exponential growth of computing power might end. That lead paragraph really needs to cite a more current reference about the future of Moore's law; six years ago is ancient history in the computing world. Red Act (talk) 07:05, 20 April 2011 (UTC)

Since you're assuming that these HP/liter would double every two years, and that HP/liter does not depend on total engine displacement, we could also phrase this hypothetical 'law' as saying that the displacement necessary to produce 1,000 HP halves every two years. To get the current displacement for take your 145 L estimate and divide by APL's figure of 2^42. SemanticMantis (talk) 00:44, 20 April 2011 (UTC)

That is 32,970 cubic micrometers of engine displacement that would hold 1,000 HP if it followed Moore's Law. What other objects can you think of that has 32,970 cubic micrometers of volume? (I doubt Google could help me on that.) --98.190.13.3 (talk) 03:40, 20 April 2011 (UTC)

In other words, 32.97 picoliters. I have Wolfram Alpha to thank for that. --98.190.13.3 (talk) 04:15, 20 April 2011 (UTC)

At 3 x 10^-11 L (or 3 x 10^-14 m³), that's about the volume of a grain of sand. Perhaps that should be "grain of salt"; it seems silly to apply Moore's law this way. -- Scray (talk) 04:05, 20 April 2011 (UTC)

Is there an article about wheel-mounted engines? I've read that the cars of the future would have an engine embedded on each wheel. I guess if there ever comes a sandgrain-sized engine, then we could fit many of them to a wheel, or even the lugnuts of each wheel. --98.190.13.3 (talk) 04:15, 20 April 2011 (UTC)

The Toyota Hybrid Highlander and some other high-end electric and hybrid gasoline/electric vehicles have assist motors mounted on two wheels, in addition to the Continuously Variable Transmission drive train. You can read more about this: Highlander Drive-Train specs; the rear motor on 4-wheel-drive variants provides an extra 50 kilowatts and nearly 100 lb-ft. of torque to supplement the Hybrid Synergy Drive. But it is hardly "small as a sand grain."

You may also be interested in the Apollo LRV, which had independent wheel-mounted motors.

To be honest, both of those vehicles represent the fore-front or "frontier" of wheeled vehicle propulsion; the original poster would learn a lot about automotive technology by reading up on such contraptions. Extrapolating trends in digital electronics technology is totally inapplicable to this topic; instead, the OP could read about trends in motor design and vehicle dynamics, to construct a meaningful extrapolation for future technology. Idle speculation without any grounding in actual physical principle, or engineering practice, is never going to help us solve the actual problems of transportation. Nimur (talk) 18:03, 20 April 2011 (UTC)

I assumed that he didn't want to learn about automobiles, he simply wanted a metaphor to enhance his understanding of Moore's Law as it applies to microprocessors. APL (talk) 02:14, 21 April 2011 (UTC)

Craps probability question

Hello scientists. I wanted to post this over at the maths desk, but the page seems to be protected against anons at the moment.

Anyway, I have devised an extremely stupid craps "strategy" where I basically hope against hope that a 7 will never come up on a roll of a pair of dice. I make "place" bets on every number, and as long as 7 never comes up I keep making money. Inevitably, 7 is always rolled and always much sooner than I expected.

I think I read on a gambling website that, even though 7 is the most common die roll, the chances of rolling a 7 on any given roll is only about 16%. But what is the probability that a 7 will come up at least once in two successive rolls? Three rolls?

Could you show me how this is calculated, all the way up to 20 rolls? I want to see mathematically how stupid my strategy is.

Cheers, --24.188.235.80 (talk) 22:51, 19 April 2011 (UTC)

Your win condition is the equivalent of a series of independent Bernoulli trials, where the probability of success (not rolling a 7) is 5/6. Since the probability of winning is 5/6 in each trial, the probability of n successive wins is (5/6)ⁿ. That's 5²/6² = 25/36 (about 70%) for two rolls, 5³/6³ = 125/216 (about 58%) for three rolls, and you can go from there. TenOfAllTrades(talk) 23:08, 19 April 2011 (UTC)

(Expanding slightly on my previous response, there are 6 possible outcomes for each die, and 6*6 possible outcomes with a pair of dice. Six of those combinations give the losing total of 7, so the chance of losing on any given roll of the dice is 6/36, or 1/6: about 16.7%. That leaves the probability of not losing at 5/6.) TenOfAllTrades(talk) 23:12, 19 April 2011 (UTC)

(ec) And, if you are wondering why the chance of rolling a 7 is 1/6 (or 16.6667%), I will describe why. Since there are two dice, with 6 numbers each, this allows for 36 possible rolls (6×6). Of these, 6 rolls add up to 7: (1-6, 2-5, 3-4, 4-3, 5-2, 6-1). So, the chance of rolling a 7 is 6/36 or 1/6. StuRat (talk) 23:16, 19 April 2011 (UTC)

Thank you, those answers make it very clear. And if it were truly a 5/6 success/failure for each throw, it would indeed be a great system. However in craps, you can only make place bets on 4,5,6,8,9 and 10. 7 means you lose; 3, 11, 12 are a push in my system... so rather than looking at it as binary W/L scenario, could we organize odds into win/lose/tie probabilities?

• LOSE: The probability that I will get a 7 and lose all the money on the table is 16.67% on every throw
• WIN: what is the probability that I will win (i.e, get 4,5,6,8,9 and 10)
• TIE: what is the probability for a push (2,3 or 12)

--24.188.235.80 (talk) 23:26, 19 April 2011 (UTC)

Sure, let's start with the odds for each possible roll:

  ROLL  ODDS
  ====  ====
    2   1/36
    3   2/36
    4   3/36
    5   4/36
    6   5/36
    7   6/36
    8   5/36
    9   4/36
   10   3/36
   11   2/36
   12   1/36

You seem inconsistent on what is a push, I will assume that 2, 3, 11, and 12 are. So, then, the odds are:

• LOSE = 6/36 = 1/6

• WIN = 24/36 (3/36 + 4/36 + 5/36 + 5/36+ 4/36 + 3/36) = 2/3

• TIE = 6/36 (1/36 + 2/36 + 2/36 + 1/36) = 1/6

StuRat (talk) 00:09, 20 April 2011 (UTC)

You might also want to know the probability of an eventual win or loss. We can determine this by removing the possibility of a tie, which leaves us with 5/6 of the cases. To "unitize" this (my own term), multiply all odds by the reciprocal, or 6/5:

• LOSE = 1/6 × (6/5) = 6/30 = 1/5 = 20%

• WIN = 2/3 × (6/5) = 12/15 = 4/5 = 80%

StuRat (talk) 00:19, 20 April 2011 (UTC)

Thanks for the detailed answer. Because we're discussing gambling, it's important to distinguish odds, from 'chances' or probability. Odds of 2:1 against means the probability of success is 1/3. I think you mean 'probability' or 'chance of occurrence' in your table above. SemanticMantis (talk) 01:04, 20 April 2011 (UTC)

Yes. (And, true to your name, you attacked based on semantics.) :-) StuRat (talk) 01:51, 20 April 2011 (UTC)

April 20

Getting rid of double chin's fat

If you go on a diet + exercise program and start to loose weight, will the fat of a double chin go away? Or is it some more resilient fat deposit? —Preceding unsigned comment added by 212.169.181.129 (talk) 00:02, 20 April 2011 (UTC)

Each person's body characteristics are unique. No general statements can be made except if you go on a properly supervised diet and exercise program, and lose weight, you will have more positive health outcomes in many aspects of your life. However, as to what such a diet will do to specific body parts and their shapes and sizes; there is no way to make a general statement, everyone is different. In other words, you shouldn't stop exercising and start eating junk food all day merely because your double chin doesn't go away... --Jayron32 00:10, 20 April 2011 (UTC)

Probably, yes. Excess fat under the chin is normally associated with obesity. However, flabby skin may remain, which can be just as bad. StuRat (talk) 00:24, 20 April 2011 (UTC)

A science question concerning light years

I have wondered about the following question for a while, and I haven't been able to figure i out. Can you please help?

Television signals are radio waves which travel at the speed of light. The first commercial TV broadcasts began about 1950. How far have these radio waves travelled in light years?

Thanks —Preceding unsigned comment added by 66.222.179.213 (talk) 01:40, 20 April 2011 (UTC)

Well, it's been 61 years, so those signals would have traveled 61 light years.. Mind you, they weren't designed to be beamed into space, neither in direction or power. So even if theoretically there is any signal left 61 light years away, it would almost certainly be completely undetectable above the "noise". Especially considering the power of the signal follows the inverse square law. Vespine (talk) 01:46, 20 April 2011 (UTC)

You may enjoy this informative XKCD image that illustrates the answer to your question (~61 light years) with its placement of 'expanding shell of radio transmissions' [4](note the logarithmic scale). SemanticMantis (talk) 02:00, 20 April 2011 (UTC)

"if there is any signal left..." I would expect that the signal did not cease to exist as it travelled 61 light years. "..it would almost certainly be undetectable above the noise.." That depends on the antenna array used by hypothetical extraterrestrials. How many dishes of what size located how far apart would be required? Edison (talk) 14:03, 20 April 2011 (UTC)

Maybe 20 years ago I read a science fiction novel where a strange electromagnetic signal being received on earth was translated to be images of Hitler opening the 1936 Olympic Games. Those Games were transmitted by television to 20 or so locations around Germany. So it's not a new idea, and the distance would now be 75 light years. HiLo48 (talk) 02:54, 20 April 2011 (UTC)

You're thinking of Contact, a 1985 novel by Carl Sagan. TenOfAllTrades(talk) 03:00, 20 April 2011 (UTC)

Yes, of course. Thank you. HiLo48 (talk) 03:09, 20 April 2011 (UTC)

Spy camera-type hardware to use as ocular implants for the blind - Why do I never hear of them?

See, this spy camera is nearly the size of our eyes. (There are some smaller models like this one, which appears small enough to fit in a child's eye socket.) If components are small enough to all fit into something that can fit into one's eye sockets, why do I not hear of the blind receiving these implants to help them see again? --98.190.13.3 (talk) 03:49, 20 April 2011 (UTC)

Because we can't yet interface the camera with the visual cortex. Shoving a camera into someone's skull does nothing if the brain can't interpret the signals as "vision." A lot of research is focusing on this issue, and there are lots of very clever schemes being investigated, but we aren't quite there yet. --Mr.98 (talk) 03:58, 20 April 2011 (UTC)

But this and this would seem to be steps in the direction you're asking about. HiLo48 (talk) 04:01, 20 April 2011 (UTC)

Definitely. Very clever schemes. Unclear which will be the one(s) that will end up being most successful in the long run. I wouldn't be at all surprised if we had some very good bionic eyes in the next two decades. But my understanding is that most of them are still too expensive, and too crude, for much practical use at this point. Making a camera is of course trivial; making that camera interface with the brain is not. --Mr.98 (talk) 11:59, 20 April 2011 (UTC)

Would a rail gun give recoil?

I understand relatively how a rail gun works; it uses a magnetic field to accelerate a projectile, if I'm not mistaken.

I'm writing a short story, and I would like to ask those more educated than myself: Would a shoulder mounted rail gun give recoil?

I'm not entirely sure how Newtons law's would affect the situation involving magnets. I await your answers. —Preceding unsigned comment added by 66.91.44.187 (talk) 05:28, 20 April 2011 (UTC)

If an object is leaving the gun, the gun must recoil with the same momentum that the object leaving the gun has, but in the opposite direction. The source of the force accelerating the leaving object, whether it is exploding gunpowder or a magnetic field, is irrelevent. --Jayron32 05:31, 20 April 2011 (UTC)

Thank you so much, this definitely answers my question. —Preceding unsigned comment added by 66.91.44.187 (talk) 05:33, 20 April 2011 (UTC)

Jayron32 has answered your question using the principle of conservation of linear momentum. You might find an answer expressed using Newton's third law of motion to be simpler. Newton's third law can be explained as Forces always occur in pairs. If object A exerts a force F on object B, then object B exerts the same force F on object A but it is in the opposite direction. In the case of the rail gun, if the gun exerts a force F on the projectile then, simultaneously, the projectile exerts the same force F on the gun but in the opposite direction. So the same force F is applied simultaneously to both bodies but that doesn't mean they have the same acceleration. The small projectile is given a high acceleration and quickly achieves very high speed. The gun with its greater mass is given a smaller acceleration and achieves only a small speed before being stopped by the surrounding structure. Dolphin (t) 05:57, 20 April 2011 (UTC)

If a cannon fired a 1 kg projectile at 500 meters/second, the recoil should be somewhat greater than if a rail gun fired a projectile of the same mass and velocity, since the conventional cannon would also expel the gases and unburned particles of the gunpowder charge. Edison (talk) 13:58, 20 April 2011 (UTC)

I suppose you could design a recoilless railgun that propelled a counterweight in the opposite direction to the projectile. Make the counterweight more massive than the projectile so that it has a lower acceleration and lower top speed. Let the counterweight eject itself from the back of the railgun. Either retrieve the counterweight after each firing and reuse, or maybe load with two-part shells so each projectile has its own counterweight. Dibs on the patent. Gandalf61 (talk) 15:19, 20 April 2011 (UTC)

The impulse would be lower. —Preceding unsigned comment added by 84.92.32.38 (talk) 19:31, 20 April 2011 (UTC)

As it says in the article on Newton's Laws, the Third Law does not apply when electromagnetic fields are considered (the field can carry off momentum). So it is possible to build a recoil-less rail gun, there being no mechanical recoil, the reaction being carried off by an EM field Robinh (talk) 23:52, 21 April 2011 (UTC)

If you want to carry momentum away from the gun, you need a radiant EM field, i.e. an electromagnetic wave. If you're talking about accelerating a bullet, the EM wave coming out the back of the gun would be very intense. I daresay that the EM wave might be more destructive than the bullet. --Srleffler (talk) 17:47, 22 April 2011 (UTC)

Let's crunch some numbers. A photon's momentum is its energy divided by the speed of light (see photon). So, the energy released as EM would need to be equal to the momentum of the projectile times the speed of light. Our article, railgun, mentions a US Navy device that accelerates a 3.4kg projectile to 2.4 km/s. That means the energy release by EM would need to be 3.4*2,400*300,000,000 J = 2.4 terajoules. Orders of magnitude (energy) says that's just under the orbital energy of the Mir space station. The Mir space station got that energy from a rocket engine burning for a period of about a minute (ish - I don't really know the length of the rocket burn, and you need to remove a bit due to atmospheric and gravity drag, but that's not important). The rail gun would need to emit that energy almost instantly. So, in conclusion, I agree with Srleffler that the EM would do more damage than the projectile (unless it was able to dissipate prior to hitting anything and was at a frequency that isn't absorbed by air, I suppose). --Tango (talk) 18:07, 22 April 2011 (UTC)

If there was not salt in oceans

what was happened if there was not salt in ocean water?--78.38.28.3 (talk) 09:55, 20 April 2011 (UTC)a.mohammadzade

All living things would be radically different. Life evolved in the context of water containing a certain combination of electrolytes, which are now are an integral part of biology as we know it. See cells, cell membrane, cell potential, electrochemical gradient, membrane transport and action potential just as a start. --- Medical geneticist (talk) 10:19, 20 April 2011 (UTC)

Your skin would become all wrinkly when you swam in it. --Aspro (talk) 10:17, 20 April 2011 (UTC)

Absurd "if." Salt is in oceans because salt (NaCl) exists, and water dissolves it. To have no salt in oceans would require the amazing position of saying that water can not come in contact with salt. Fresh water exists because water in clouds has essentialy no salt in it - fresh water in aquifers is "old rain". And, yes, some aquifers are brine (having salt in them). Collect (talk) 11:15, 20 April 2011 (UTC)

It's a hypothetical situation. Dauto (talk) 13:58, 20 April 2011 (UTC)

Of course it is, but you can't give a sensible answer to this kind of hypothetical question without considering why the thing you've changed is different. You can't just change the salinity of the oceans in isolation. You need to make sure your new world is still consistent with the laws of physics. If you throw physics out the window, you have nothing to work with and can't get any answers at all. --Tango (talk) 18:32, 21 April 2011 (UTC)

Hmmm, I thought there wasn't much salt in the oceans when they formed on Earth. Count Iblis (talk) 17:12, 20 April 2011 (UTC)

A different way of approaching the question is could life have evolved on Earth without the elements Sodium and Chlorine being present? Exxolon (talk) 17:34, 20 April 2011 (UTC)

Many organisms (not explicitly adapted to be salt tolerant) actually prefer to keep their intracellular environment lower in sodium and higher in potassium than we observe in the modern oceans. Those preferences have been used to suggest that the last universal common ancestor may have developed under conditions with appreciably less sodium and perhaps more potassium than we observe in the modern oceans. (Though on the other hand, the common ancestor may simply have realized that exporting sodium and importing potassium was a good way to live.) Dragons flight (talk) 21:02, 20 April 2011 (UTC)

I think all life died and all of oceans became waste water in less than one month.--78.38.28.3 (talk) 03:19, 21 April 2011 (UTC)

THE best way of transferring water up to top of the hill

what is THE best way for transferring water up to top of the hill?--78.38.28.3 (talk) 09:55, 20 April 2011 (UTC)a.mohammadzade

I don't understand your use of the word "mentions". Maybe if you posted here in your native language, we can get someone to translate it to English for us and give you a meaningful answer? --TammyMoet (talk) 10:52, 20 April 2011 (UTC)

"بهترین روش برای انتقال آب به بالای کوه کدام است " —Preceding unsigned comment added by 78.38.28.3 (talk) 03:03, 21 April 2011 (UTC) چند وقت پیش یک سیستم در نظر داشتم ایجاد کنم که اب را در ارتفاع پایین به بخار تبدیل می کند و در بالادست (بالای کوه یا ارتفاعات )دوباره به اب تبدیل می کند این سیستم همان شیوه ای است که خداوند در طبیعت قرار داده سیتمی که اب اقیانوسها را به بالای قله 8800متری اورست می فرستد نه پمپی در کار است ونه لوله کشی .به نظر بنده بهترین روش و ارزان ترین روش انتقال آب این است"--78.38.28.3 (talk) 03:09, 21 April 2011 (UTC)

the best way may be which the nature does , vaporation in down , and devaporation on top ,without pomping and pipes .--78.38.28.3 (talk) 03:16, 21 April 2011 (UTC)

Google Translate, which isn't perfect, say's that's Persian for "The best way to transport water to the top of a mountain which is" (sic), so in proper English the question is presumably "What is the best way to transport water to the top of a mountain?". Red Act (talk) 03:15, 21 April 2011 (UTC)

THANK YOU VERY WELL >THOSE ARE MY MEANING. —Preceding unsigned comment added by 78.38.28.3 (talk) 03:21, 21 April 2011 (UTC) It was for my spelling "mountain" —Preceding unsigned comment added by 78.38.28.3 (talk) 03:25, 21 April 2011 (UTC)

We have these articles, that may help: fa:چرخه آب (Water cycle), and pump (fa:پمپ). Generally, we try to engineer a water distribution system that doesn't require sending water up hill. In the middle-east, elaborate systems called fa:کاریز or قناة in Arabic - (Qanat, for the English-speakers) is sort of like a man-made artesian well (fa:چاه آرتزین). When it is unavoidable, and we must send water up-hill, we usually use large electric pumps. We have diagrams of many types of water pumps at our article. The largest types of pump I am aware of are radial piston pump, though I am not a water utility specialist.

Near to where I live, we have a reservoir called Hetch Hetchy, which is unfortunately on the opposite side of a mountain from where most people live. You can see photos of the gigantic pipes that were built to carry water over the Sierras and eventually all the way to the greater San Francisco region. I've driven past this particular vista-point many times, and often wondered how they make the water flow up-hill; I still don't know if it's ultimately a gravity pump (i.e., the reservoir is higher than the final destination, so the water is simply siphoned over this hill), or if energy needs to be added via electric pump to make this particular climb. (It's on CA 120 near Old Priest Grade Road and Moccasin Reservoir, if anyone knows what I'm talking about). You can't miss it, if you're driving to Yosemite. I'd wager that it's one of the steepest up-hill aqueducts in the United States. Nimur (talk) 04:11, 21 April 2011 (UTC)

Since you're from Persia, you might also be interested in an ingenious way the Persians employed to cool their buildings, thereby moving water from a qanat: Windcatcher, in Farsi: بادگیر. — Sebastian 07:32, 21 April 2011 (UTC)

For an older (and in my humble opinion, more elegant) approach, see Archimedes' screw. --Rixxin (talk) 09:13, 21 April 2011 (UTC)

Using an aquaduct is an old solution to crossing a valley. 92.24.189.51 (talk) 10:17, 21 April 2011 (UTC)

you have good ideas and very informations about my nation , and our last irrigation systems , cooling buildings and our way of refrigerating food in underground .THANK YOU--78.38.28.3 (talk) 11:05, 21 April 2011 (UTC) last iranians was prefer to find upper code for water flow to their farm or garden , and had not pomp,to upgrade level of water code--78.38.28.3 (talk) 11:12, 21 April 2011 (UTC)

I don't understand the word "kode" here. If the problem is a lack of electricity at the site, then solar and/or windmill energy might be the best way to power the pumps. Placing those at the top of the hill would probably provide for the best results, especially in the case of a windmill. Note, however, that these will provide a rather intermittent flow of water. If this is just for irrigation, that may be acceptable. However, if you also need a supply of water available at the top at all times, then a tank or pond of some type is needed at the top. Also, if the hill is high, it might make sense to use a series of pumps which each pump to a tank a bit higher up, rather than one huge pump at the bottom. Sump pumps have floats and only turn on when there is water to pump, so those might be the best choice here. StuRat (talk) 17:26, 21 April 2011 (UTC)

Rat population dynamics

There was a public health expert on the radio yesterday discussing the public health consequences of an ongoing strike by sanitation workers. He said that if the trash piles up uncollected for more than about 3 weeks the city will have a dramatic increase in rat numbers. He went on to explain that three weeks of plentiful food is all it takes for the rat population growth rate to reach a "tipping point" where a previously stable population in equilibrium with its limited food supply suddenly adjusts to its new increased food supply. I'd like to understand the population dynamics at work. Is it a case of increased fertility or is a decreased mortality the main factor. What makes "about three weeks" be a critical period? The city under discussion is Johannesburg in South Africa - a large metropolitan city with a population of several million people (and who knows how many rats). Roger (talk) 08:50, 20 April 2011 (UTC)

Brown_rat#Reproduction_and_life_cycle--Aspro (talk) 10:22, 20 April 2011 (UTC)

That doesn't explain the mechanism of a population explosion. Do litter sizes directly increase in response to improved nutrition? If so, how long does it take to occur? Rats that are already pregnant on day 1 of the sanitation strike can't contribute to such an increase. Surely a sustained period of plentiful food would be required to increase fertility - I can't see how for example a single good meal could cause "superovulation".

Does decreased mortality play a role? My "gut" says that lower mortality would take considerably longer than three weeks to greatly influence total population size. I supose what I'm really after is a statistical demographic analysis of a rat popultation explosion in response to increased food supply.

I remember seeing a documentary - I think on Nat Geo TV - about the rat population explosions in parts of India that occur in response to bamboo forest coming into seed at the same time, iirc, every 40 or so years. That process took substantially longer than simply the gestation period of the rats - in fact it took several "generations" for the population to "explode". Roger (talk) 10:44, 20 April 2011 (UTC)

Yes, I saw that too. I recall that not only did a higher percentage of baby rats survive, there were also more born per litter and less time between litters at the peak. Then, when the food supply disappeared, the rats started starving and would eat anything they could find. One interesting effect is that it doesn't actually seem to be in the interest of the species to do this population explosion followed by starvation, but it is in the individual interest of each rat to have as high of a percentage of their genes in the surviving rats as possible. Seems like their are some lessons about human overpopulation in there. As far as a "tipping point" goes, there may be a certain amount of time and excess calories needed for the rats to switch to higher fertility mode. StuRat (talk) 23:47, 21 April 2011 (UTC)

Rates live in a rate race. Young rats have very high mortality ratios that favour older rats. With a plentiful food supply most young rats can survive and so the population starts to exploded. As the increase is counted on a generation bases – it takes a minimum of three weeks to make this assertion. That section seems to make this clear to me. Maybe your trying to read too much into it.--Aspro (talk) 13:15, 20 April 2011 (UTC)

Mice and rats are actually well known for eating their young. I don't know for sure, but I suspect the "tipping point" is that once the rats are old enough, reducing their food supply means that they come into your house looking for any scrap, rather than being peacefully eaten by their mothers. Wnt (talk) 17:26, 20 April 2011 (UTC)

Notoungulata

Hi!

In the Notoungulata article it is mentioned that these animals lived also in Asia (there is a map as well). What is the explanation of this, as South America was not connected with other continents in the time of Notoungulata (57 mya)?92.84.196.241 (talk) 10:24, 20 April 2011 (UTC)

Go back to the "Notoungulata" article and under "taxonomy" click on "convergent lines" It's all very well explained.Phalcor (talk) 14:07, 20 April 2011 (UTC)

Those from Asia, are not real notoungulates, but notoungulat like creatures? 92.86.240.138 (talk) 14:13, 20 April 2011 (UTC)

No, Phalcor, you misread the article. Notoungulates in South America evolved (via convergent evolution) to fill many of the niches other mammals filed on other continents. But it's not the case that Notoungulates evolved twice (or thrice, given the two disjoint areas in South America). One explanation for the disjointness of areas is that fossilization is a rare event. We may not have any fossils from some areas where Notoungulates lived. I have, however, no idea if there ever was a land connection from Asia to South America during the last 57My. --Stephan Schulz (talk) 15:42, 20 April 2011 (UTC)

Our article on notoungulata is actually out of date, I believe -- or rather, the map is out of date. The putative Asian members consist of Arctostylopida, which were once thought to be notoungulates but are now classified differently. It would clearly be impossible to have a monophyletic group of land mammals from Asia and South America starting 57 million years ago (as our article says), because South America had already been separated for around 40 million years by that time. Looie496 (talk) 16:57, 20 April 2011 (UTC)

(Edit Conflict) Googling on the subject, some authorities have evidently suggested that the Notoungulates originally evolved in East Asia (as mentioned here) but there seems to be some debate (as here) about whether the sub-orders or families in Asia (and those in North America) that have previously been classified within the Order Notoungulata are truly members or not. The ancestry of Notoungulata also seems less than certain. it would be interesting to know how those who endorsed the Order's monophyly explained their distribution. As in all science, everything is open to revision in the light of new evidence or improved analyses. In short, the OP may well be right. {The poster formerly known as 87.81,230.195) 90.197.66.111 (talk) 17:18, 20 April 2011 (UTC)

Yes, as my response above indicates, the OP is absolutely right. I have just taken a shot at fixing the Notoungulata article to give a more up-to-date picture. I can't fix the map, unfortunately. Looie496 (talk) 17:37, 20 April 2011 (UTC)

Thank you for the answers! 109.96.200.104 (talk) 06:59, 21 April 2011 (UTC)

I removed an absurd bit of math in the lede to that article, which said that, since they existed from 57 million years ago to 11,000 years ago, they were around for 56,989,000 years. This reminds me of this funny dialog:

KID: "Hey mister, how old is that dinosaur ?"

GUARD: "200,000,007 years old."

KID: "How do you know so exactly ?"

GUARD: "Simple, it was 200,000,000 old when I started working here, seven years ago." StuRat (talk) 18:06, 21 April 2011 (UTC)

Hollow plant stems

What are hollow plant stems like those from dandelion good for? 95.112.153.119 (talk) 12:54, 20 April 2011 (UTC)

Hollow structures can provide stability without additional mass; for example many birds have hollow bones, which provide strength, but are also light enough for the bird to fly (see Bird_anatomy#Skeletal_system. In the case of dandelions, the hollow stem may allow faster production (i.e. less resources needed to produce) while still providing the strength and function that a stem is supposed to provide. It should also noted that some cousins of dandelion (like Catsear) do not have hollow stems, so its likely one of those multitude of traits which is "optional". --Jayron32 14:36, 20 April 2011 (UTC)

The hollow stems are also good for amusing young children et. al.. If you take a 6 - 8 length of dandelion stem, the thicker the better, squeeze the bottom half inch and separate the two halves so that the two sides separate into two outward curving 'reeds' then place the 'reed' end inside the mouth and blow gently. Once you have acheived a 'note' then with hands cupped around the open end and some tongue trilling, you're away. The summer evenings will fly by! Richard Avery (talk) 15:41, 20 April 2011 (UTC)

Isn't the white sap poisonous? --TammyMoet (talk) 19:52, 20 April 2011 (UTC)

Not that I know of. Dandelions are quite edible, and parts of them, or their close relatives, find their way into all sorts of recipes. I've had dandelion greens in a salad often enough, and being a cousin of chicory, dandelion root makes a decent ersatz coffee substitute. The flowers (pre-puffball stage) are perfectly edible and are often used to make wine. I've never heard that the sap was particularly toxic; if it were it would make all of the other parts toxic as well, which they clearly are not. --Jayron32 20:06, 20 April 2011 (UTC)

As child I was told the sap was toxic (which it really isn't). I think this is a common myth at some places. Likewise, any unknown berries were called "birds berries" and declared poisonous. 95.112.153.119 (talk) 20:17, 20 April 2011 (UTC)

Yes, I remember being told that dandelion sap was poisonous. I wonder where the idea came from, and if there are any unpleasant chemicals in the sap. Dbfirs 22:42, 20 April 2011 (UTC)

I don't think I was told it was poisonous but I do remember that it is quite bitter and not very pleasant tasting. Vespine (talk) 23:03, 20 April 2011 (UTC)

Yeah, I was never told (or didn't bother to listen to those trying to tell me) it was poisonous, and discovered the same thing. It tastes crap. HiLo48 (talk) 23:48, 20 April 2011 (UTC)

I also prefer beefsteaks, French fries and chocolates. I put the dandelions in vinegar (in a jar that previously contained gherkins. Yes, yes, I reuse nearly everything) and eat it in quantities like mustard. (Oh, I see, I have different customs with mustard, too. So that is 3-5 tablespoons per dish.) I hope the vinegar also releases the minerals from phytic acid. 93.132.132.156 (talk) 00:12, 21 April 2011 (UTC)

The sap is interesting because it's latex. I sometimes wonder about its potential for craft activities (but it's probably easier to go out and buy a big bottle of latex than harvest several hundred dandelions).  Card Zero  (talk) 10:44, 21 April 2011 (UTC)

As a child, I was told it would make me wet the bed if I ate it, hence the alternative (and French-equivalent) name piss-a-bed. I now fail to see a mechanism by which this could be true, and I've never known anyone to experience it. I did discover, as a child, that the sap stains your skin, and so can be used to give yourself temporary tattoos. This is also how I know eating the sap doesn't make you piss. 82.24.248.137 (talk) 22:07, 21 April 2011 (UTC)

It is said to be (without mentioning any mechanism) to be a diuretic, which is simply another word for "it will make you piss". 93.132.132.156 (talk) 22:36, 21 April 2011 (UTC)

Well, yes (I deliberately stuck to the terms used in the folk-name), but being a diuretic isn't as specific as making you urinate while asleep, or even making you urinate at all: it just fills your bladder quicker. And, given children pretty commonly get the stuff on their hands and end up eating it, we can clearly see that any effect it has is much less dramatic than the folk tradition has it. And it certainly doesn't involve any sleep-triggered weeing (which was the ridiculous claim). 82.24.248.137 (talk) 22:11, 22 April 2011 (UTC)

Smell of salt

When I pour salt into boiling water, there is a characteristic smell of salt. I thought that this may be due to small droplets which are created as the ascending vapor bubbles reach the surface transporting the salt, or just by the flow of air and vapor which may transport very small salt grains, but the smell is also there when I heat water that has been salted when it was cold, long before it boils. This leads me to the question: What is the vapor pressure of sodium chloride at e.g. 80 degrees Celsius? The sodium chloride vapor pressure (or the vapor pressure of the Na⁺ or Cl^- ions for that matter) shouldn't be higher above the solution than above solid sodium chloride, it wouldn't be soluble (up to 356 g/l or more, depending on temperature, a concentration that I certainly didn't reach) otherwise. Icek (talk) 12:54, 20 April 2011 (UTC)

It's a common misconception that something has to strictly be a gas for you to smell it. It merely needs a mode to get into your nose. It's quite possible that very small salt crystals could become airborne, as you say transporting "very small salt grains", or in the case of a solution very tiny droplets of salty water could become airborne which can transport the salt to your nose. These sorts of macromolecular mixtures of particles are called Colloids, and a description of various types can be found at Colloid#Classification_of_colloids. There are lots of ways for salt to get to your nose, either in solid or solution form, which do not require detectable amounts of "NaCl" gas, which do not exist at all under normal household conditions. According to this MSDS, sodium chloride has a vapor pressure of 1 torr at 865C, which likely means it is immeasurably small at merely 80C. --Jayron32 16:57, 20 April 2011 (UTC)

Also, if this is iodized salt, is it possible you are smelling the iodine (which has a very strong odor) ? StuRat (talk) 17:35, 21 April 2011 (UTC)

Iodized salt contains no iodine anymore than regular salt contains chlorine. Iodized salt contains iodide or iodate which has many more differences from iodine than the mere change in spelling. Yes, elemental iodine contains a very distinct odor, but you don't find elemental iodine in iodized salt. --Jayron32 23:43, 21 April 2011 (UTC)

Iodized salt contains no iodine ? Since both iodide and iodate contain iodine, that means the iodized salt does too. And salt contains chlorine by the same logic. Now, if you mean it doesn't contain elemental iodine and chlorine, then OK, but you need to say it that way. StuRat (talk) 09:55, 22 April 2011 (UTC)

Also, iodized salt certainly tastes different, and I believe I can smell the difference, too. StuRat (talk) 00:13, 23 April 2011 (UTC)

Iodized salt contains either the I^1- ion or the IO₃^1- ion. Both of those ions will have a different taste than the chloride ion in normal salt; as well the counterion for introducing the iodide and iodate ions is often potassium, which will introduce its own taste. Additionally, the mechanism by which you "smell" pure sodium chloride is the same for smelling "iodized" salt. When you think of volatile iodine, that is elemental iodine, that is I₂, which is not I^1- or IO₃^1-. Iodide and iodate have no vapor, and so do not have a strong smell (unless they get into your nose as already described above). Iodine (I₂) is highly volatile and has a distinct smell. There is no I₂ in iodized table salt. What you are doing is confusing the properties of very different substances with similar names. --Jayron32 00:53, 23 April 2011 (UTC)

Edible plant parts

I can't find an article about that. Worse, there are many articles that try to cover it. When I look at the plant in my garden, I get hungry and start to wonder what can be eaten. I somewhere heard that all parts of rosaceae are edible. Is that true? What about hazel leaves and catkins? Sorry if this looks near to trolling. 95.112.153.119 (talk) 13:19, 20 April 2011 (UTC)

No, it doesn't look like trolling, it does look like an honest question, which I will endeavor to honestly answer. The term for an "edible plant part" is a Vegetable. However, there are no general rules for which plants, or which parts of which plants, are automatically edible. Take cashews for example: The seed itself is edible, but surounded by a shell and a fruit which is pretty toxic. Contrawise, the apple has a very edible fruit whose seeds contain cyanide, which is toxic (see Apple seed oil). Then you have stuff like pokeweed, which is toxic in raw form, and edible when cooked properly. Your best solution to deciding what to eat is to first research the specific plant in question. --Jayron32 14:19, 20 April 2011 (UTC)

It is certainly not true that all parts of rosaceae are edible. The family includes many fruit trees, whose wood is obviously not edible. Looie496 (talk) 16:31, 20 April 2011 (UTC)

This depends on what exactly is meant by "edible". Pearwood is surely not chewable, but neither is raw sweet corn. Salad, in contrast, is chewable, but contains nearly nothing to nourish you. So aside from the normal use of the word, I would not exclude that some woods are "edible", in some sense. 95.112.153.119 (talk) 17:44, 20 April 2011 (UTC)

"Salad....contains nearly nothing to nourish you". No, its packed with vitamins, minerals, antioxidants etc. There is much more to food than mere calories. Datrk leaf vegetables such as cabbage are better for you than lettuce, but lettuce is still good. 92.15.24.113 (talk) 21:21, 20 April 2011 (UTC)

I think that's a myth. It's mostly indigestible cellulose and water. (See Green Salad: "Due to their low caloric density, green salads are a common diet food.") The tiny amount of minerals is largely indigestible, too, as it is bound to phytic acid and for vitamins there are richer sources elsewhere. 95.112.153.119 (talk) 22:01, 20 April 2011 (UTC)

Compare the nutrition tables from dandelion with lettuce, OK dandelion leaves if prepared are also called "salad", but so is potato salad. 95.112.153.119 (talk) 22:37, 20 April 2011 (UTC)

Both lettuce and dandelions are packed with nutrition, and luckily have few calories. The dandelion table simply includes more nutrients than the lettuce table does. Neither of the tables include antioxidants etc. I agree that eating a lettuce is not quite as good as darker-leaved vegetables, but its still good. Something very important is that eating veg and fruit fills you up and thus avoids you eating high-calorie junk food. If you were starving then yes, a Big Mac would be more nutritious for you than a plate of salad, but few people reading this are going to be starving - most will be overweight and consuming too many calories than is good for them, particularly in North America. OP, I'm willing to bet that you are not underweight. 92.28.253.8 (talk) 10:05, 22 April 2011 (UTC)

Actually I was slightly underweight during childhood and adolescence. Now I am in my late forties and gaining some additional weight. I bet you are not underweight, despite your mainstream healthfood? If your stomach is trained to do work, it will start to work even if you don't need food. This is what most people in the western world think of as hunger. If you don't need food, the simplest thing to do then is to ignore the feeling and your colleagues' strange looks for the sound of a rumbling belly. 95.112.196.91 (talk) 12:24, 22 April 2011 (UTC)

Here's why you should eat lots of fruit and veg: http://www.nhs.uk/Livewell/5ADAY/Pages/Why5ADAY.aspx Persionally, I also think that since we evolved eating plenty of fruit and veg, it is wise to continue to do so for optimum health. 92.15.5.152 (talk) 20:34, 22 April 2011 (UTC)

Some salads are nutritious, others aren't. A garden salad is high in fiber, vitamin A and vitamin C, and has a bit of iron and calcium, too: [5]. Adding some meat (or nuts or beans) to the salad provides for protein, too: [6]. Croutons add starch. Egg adds cholesterol. Then salad dressings add fat and sugar. So, a salad can be a full meal: [7]. StuRat (talk) 18:21, 21 April 2011 (UTC)

Vegetable is the key word and I really don't know why it didn't come to my mind. Thus I fond List_of_vegetables and List_of_plants_with_edible_leaves. Nevertehless, it looks kind of futile trying to list *all* edible parts in one or two articles. Wouldn't it be better to have some box in each plant article stating the edible parts? (The way it is done with main properties of chemical elements). 95.112.153.119 (talk) 17:44, 20 April 2011 (UTC)

Again, you'd have to define "edible". Just about anything that doesn't kill you (at least, kill you mostly instantly) and which can end up in your digestive system somehow is considered "edible" by some culture. And even much of the stuff that kills you, people have found ways to render it less toxic (see the aforementioned pokeweed). --Jayron32 20:01, 20 April 2011 (UTC)

In the context of this question I think of "edible" as "non-toxic when eaten raw in quantities reasonable for other kind of food" 95.112.153.119 (talk) 20:23, 20 April 2011 (UTC)

Note that means you're counting things like cassava and probably cashew nuts as inedible Nil Einne (talk) 23:09, 20 April 2011 (UTC)

(Second try, somehow the first answer didn't get through) Yes, in the context of this question, cassava and a lot more things would not be considered edible (if not further processed). But I make this restriction only to not further complicate the original question. Any answers the like of " beans are poisonous if raw but edible if properly cooked" are highly welcome. 93.132.132.156 (talk) 00:58, 21 April 2011 (UTC)

For safety sake it's also important to bear in mind that many toxic plants are easily mistaken for non toxic plants. There can be a problem with accurate identification. So if you feel a desire to eat plants from your garden (the gatherer instinct) it might be a good idea to plant seeds or plants that are known to be safe to eat.190.56.14.28 (talk) 21:28, 20 April 2011 (UTC)

My garden behaves in a quite autonomous way. Everything I deliberately plant will almost surely not grow. Full grown trees, weeds and the roof tiles from the little house are among the few things the slugs don't eat. That is why I'm putting it the other way round and start from what I find there. 95.112.153.119 (talk) 22:17, 20 April 2011 (UTC)

All gardens behave in an autonomous way unless they are controlled. plants that are commonly eaten by humans have been selected and developed over countless generations for good reasons. If a plant is not eaten by local organisms, there is virtually always a good reason for that too. Those reasons would include considerations like unpalatability, indigestability, toxicity, thorns, tough husks etc. Sufficient botanical knowledge for safe eating would have to be a lot more extensive than "how to grow a vegetable garden" and there's a wealth of information about that.190.56.14.125 (talk) 23:13, 20 April 2011 (UTC)

And then you face the challenge of countries like mine, Australia. An Aboriginal culture thrived here for 40,000 years, on a plant collection almost entirely different from that known to the rest of the world. Unfortunately much of that culture and knowledge base about what was good to eat and how to prepare it was destroyed before we bothered to learn it. So there's still plenty of good food there. We just need to (re)discover it. HiLo48 (talk) 23:43, 20 April 2011 (UTC)

So you perfectly understand my purpose, only that the reason why the knowledge was lost (or never existed) is different. 93.132.132.156 (talk) 23:56, 20 April 2011 (UTC)

(ec) What I already harvested are dandelion leaves, blackberry leaves (intended for making tea) and ground elder (not really my taste but abundant). I could not find out if hazel leaves and catkins are edible. The shrubs have to be cut anyway and I am too big a niggard to grant anything to the slugs that could otherwise be used. Petals from wild roses are to show up soon, and I think the can be eaten or dried for tea, too. Young raspberry sprouts are really, really full of little thorns, especially near the ground and thus ward off the slugs. Ivy is clearly not for food. Common grasses are probably not toxic, but as I am not a ruminant I can't take profit from eating. There is some kind of juniper shrub but I am not certain if I can use the berries safely as spice. There are lots of unidentified "herbs" but ion total not enough to bother if they are edible or not. 93.132.132.156 (talk) 23:56, 20 April 2011 (UTC)

Elder berries are great for making a delicious rich red wine.190.56.18.243 (talk) 02:24, 21 April 2011 (UTC)

Richard Mabey wrote Food for Free, which gives details of edible wild plants in Britain. Since that book was written, it is now known that nettles have tiny calcium structures in them that damage kidneys and bladders, so only the young green tops should be eaten. 92.28.253.8 (talk) 10:10, 22 April 2011 (UTC)

Human kindness

So, in this article there's a reference to an OECD study which among other things tried to report "kindness" by country which includes things like volunteering, helping strangers, etc. However, this is self-reported, so people may be lying. I seem to recall reading about an actual study where people pretended to be injured on the street in different countries and tracked the response time and rate from general populace. Can someone help me find this or any other study that's not based on self-reporting? --216.239.45.4 (talk) 16:40, 20 April 2011 (UTC)

Desmond Morris did such studies as part of (I think) his TV series The Human Animal though he may simply have been replicating earlier studies. Our article links to videos of the episodes. I'm sure I've read that book, but I don't recall offhand whether this was in it. Matt Deres (talk) 19:56, 20 April 2011 (UTC)

I would be interested to see how efforts to get objective measures of this would be designed. It's obvious that in every society you get some very caring, sharing people, and some selfish bastards. (That's a simple Australian expression whose meaning should be pretty clear.) But the societies would also differ in so many other ways too. How to isolate the sought after variable is the challenge here. HiLo48 (talk) 23:38, 20 April 2011 (UTC)

The stuff that Morris presented was very basic stuff. Essentially they had someone lay down on the ground, apparently unconscious and they timed how long it was until someone stopped to help. IIRC, the two instances they showed on the video were one from a small Mediterranean village and one from a large city (New York or London or something). In the small village, help was offered almost instantly - the first person to see the "casualty" knelt down to check on him; in the big city, the casualty was simply stepped over. Morris wasn't attempting to examine whether different nationalities or ethnicities were more or less helpful, however, he was pointing out that people in large cities are forced to shield themselves from the crowd to the point where normal human compassion is over-ridden.In smaller communities, people can interact with virtually everyone in some kind of meaningful way (know their name, etc.) while in large cities being that open would be completely overwhelming, if not impossible. In response, people "fence off" the masses around them to the point where they almost don't identify them as being human (or at least worthy of human interaction). Matt Deres (talk) 01:23, 21 April 2011 (UTC)

What an interesting question for the science desk! It's not easy to come up with truly objective and culturally independent ways to measure this. Some ideas off the top of my head:

1. Act as a beggar, and divide the money collected by the average income. (To remain true to the spirit of the givers, the researchers should pass the collected money to a charitable cause.) Problems with that: (a) In countries with a good social net, people will feel less need to give to a beggar. (b) You would need several beggars per measured region to neutralize variations in gender or age preferences.
2. Inquire in lost-and-found offices how many items are collected per year.
3. One value for which good data exist is income equality; I'm wondering if that can be used for this purpose; I can imagine a correlation to kindness, at least in a free country. — Sebastian 07:54, 21 April 2011 (UTC)

Given that many people in a wide variety of cultures, perhaps all cultures to some extent, place what is essentially a karmic value of one form or another on actions that an observer may identify as kindness, I think distinguishing between unconditional kindness (altruism) and kindness as a cultural virtue, a form of reciprocal altruism (even if the benefit is expected to come much later such as in an afterlife etc), might be difficult even if you asked each person why they did what they did. I guess many people may not know exactly why they did what they did. "Kindness" seems like a difficult thing to measure. Sean.hoyland - talk 11:24, 21 April 2011 (UTC)

(OP here) I think I don't care if it's cultural or pure altruism. It certainly wouldn't matter much to a person who needs this sort of help. I also don't care if one can't measure "kindness" in general, but only a specific element of it, such as willingness to help strangers which is not nearly as vague. 216.239.45.4 (talk) 16:38, 21 April 2011 (UTC)

This American Scientist article from 2003 may interest you then. Sean.hoyland - talk 17:38, 21 April 2011 (UTC)

Thanks, that's exactly the sort of thing I wanted. --216.239.45.4 (talk) 19:31, 21 April 2011 (UTC)

pvc

does pvc yellow from light or only abs — Preceding unsigned comment added by Kci357 (talk • contribs) 21:37, 20 April 2011 (UTC)

I think that needs a bit of elaboration/clarification before it's likely to get an answer. You need to expand the seeming abbreviations of "pvc" and "abs", and clarify whether you mean "yellow" as a verb (meaning gain a yellowish colouring). It's not really clear at this stage. HiLo48 (talk) 02:24, 21 April 2011 (UTC)

The question is about polyvinyl chloride and acrylonitrile butadiene styrene.

My girlfriend has lots of PVC dog agility equipment that's been kept outdoors in the sunlight for in some cases over a decade, and so far at least it hasn't yellowed at all that I can tell. Red Act (talk) 02:55, 21 April 2011 (UTC)

There are different grades of PVC some will yellow, some won't. If you want to be sure get CPVC or check that they PVC you are buying is rated for UV exposure. I don't know about ABS, but I imagine it's similar. Ariel. (talk) 04:11, 21 April 2011 (UTC)

April 21

Venus

If people don't start protecting the environment from greenhouse gases, will Earth become like Venus (9 MPa CO2 atmosphere, 850 F surface temperature, sulfuric acid rainstorms, etc.)? --75.40.204.106 (talk) 02:07, 21 April 2011 (UTC)

Unlikely. For one thing, Earth's living systems are surprisingly resiliant, and are quite able to alter the atmospheric composition in dramatic ways. Don't get me wrong, humans impact on the environment, to change it from the world we know, into something far less friendly for us to live in, is a serious deal. We stand in real danger of making the world a less hospitible place for humans, and doing real harm on a timescale which is quite long on human measurements, but short on the Geologic timescale. Lets say we screw up the environment for the next 10,000 years. That's like 500 generations on a human timescale, and longer than there has been evidence of human civilization. It seems like a serious issue, and it is for us. However, 10,000 years is a minor blip on a geologic timescale. Consider that life on earth has existed for something like 2,000,000,000 years, and that 10,000 years seems insignificant to the Earth. And it is. The "earth" will recover, ultimately, from whatever we do to it. The question becomes, for me, if we will be around to enjoy it at that time... --Jayron32 02:15, 21 April 2011 (UTC)

Was Venus like Earth a long time ago until its life destroyed the environment? --75.40.204.106 (talk) 02:17, 21 April 2011 (UTC)

No, quite the contrary, there has never been life on Venus. Indeed, pre-life Earth used to look a lot more like Venus; the introduction of life drastically changed Earth's atmosphere in some very big ways. See Great Oxygenation Event where the atmosphere of the Earth changed drasticly. --Jayron32 02:56, 21 April 2011 (UTC)

According to Oxford Professor Fred Taylor, "In the light of the new data [from Venus Express] it is possible to construct a scenario in which the climates on Venus and Earth were very similar when they started out, and then evolved to the state we see now, like twins separated at birth. Billions of years ago there is even the possibility that Venus would have been habitable." Clarityfiend (talk) 03:01, 21 April 2011 (UTC)

Venus is significantly closer to the sun than is the Earth. (The average distance from the Earth to the sun is about 40% greater than the average distance from Venus to the sun.) The greater intensity of solar radiation on Venus has always represented a significant difference between the two planets and shows they could never have provided similar environments for living things, nor will they ever be similar. Dolphin (t) 03:02, 21 April 2011 (UTC)

(edit conflict) I can accept a similarity between Earth and Venus a long time in the past, but "habitable" does not equal "had life". I'm not saying you or your source said that. But it must be made clear that there's nothing there to indicate that there ever has been life on Venus. I could have married Jennifer Lopez. Doesn't mean it happened... --Jayron32 03:04, 21 April 2011 (UTC)

Hummmn. Got thing for J Lo huh?190.56.105.52 (talk) 04:50, 21 April 2011 (UTC)

People seem to disregard the fact that evolutionary processes are influenced by feedback-loops. So is climate evolution - an increase of atmospheric carbon dioxide will, through a chain of cause and effect, alter our rate of CO2 output.

For instance, assume that the only source of CO2 is industry. A drastic change in atmospheric CO2%, will eventually alter and reallocate sociological and economical priorities, including industrial sectors. As global industry shuts down a number of sectors, atmospheric CO2% decreases. Given a chance, the climate will heal itself and reajust to a new equilibrium. In short, alteration of the climate will automatically affect our ability to alter it.

I'm not argueing against global wariming, infact, I believe that at present the collective effort to change climate altering habits is insuffient to prevent the progress of global warming. Assuming that the effort remains unchanged into the future, then civilaisation will collapse, we will be forced to change our habits as it would no longer be energetically favourable to continue carbon dioxide producing technologies. Over time, global warming will naturally reverse, albeit slowly, as it is reabsorbed by ecogenesis and other minor processes.

Venus atained its current climate without the benefit of a negative feed-back loop, it actually suffered from a positive feedback loop. Plasmic Physics (talk) 11:47, 21 April 2011 (UTC)

Jayron, I don't think we can really make a statement like "there has never been life on Venus". In fact, I don't think that we can state with authority that it isn't there now. APL (talk) 14:00, 21 April 2011 (UTC)

I can't state with authority that I even exist. There's no definitive proof that Wikipedia itself is not a halucination that you are having as a result of being administered powerful mind altering chemicals placed in your tapwater supply by the CIA, and that this entire conversation isn't happening inside of your own deluded mind as you are actually, right now, lying on the floor in your living room drooling on yourself. Can you prove THAT to not be true?

Back to the life on Venus issue: Its the positive assertion that requires evidence to prove it, not the negative one. We don't assume every utterance a human could make to be true by default, and then require others to disprove it. I could make any number of rediculous assertations (Clouds used to be made of cotton candy, but they arent anymore!, Elvis Presley didn't die, he had plastic surgery and became George H. W. Bush! Grilled Cheese sandwiches cause pregnancy!), and there's no requirement that we give them any possibility of being true. You seem to be taking the stance that "any nondisproven idea must be at least considered to be possibly true". That's not necessarily the case, since I can present any number of statements that have not been disproven (to any arbitrary standard of proof I wish to demand) and then demand that you accept them as possibly true, no matter how rediculous they may be. A scientist has presented data that there may have been conditions on Venus, in the past, which may have been similar to conditions under which life on Earth is known to have existed. We can entertain that idea (we are not required to accept it as absolutely true, but we can entertain it) because the assertion is at least backed up with data. However, there is no need to entertain wild speculations that have zero data to back them up, for example, that there was actually life on Venus. Yes, you can say "you don't KNOW there was no life on Venus." But there's no need to prove the negative; the lack of any evidence is enough so far. Since you are making the positive assertion (there may have been life on Venus), you need to supply the evidence to make it. See Argument from ignorance, which is exactly the fallacy you are committing here. --Jayron32 15:34, 21 April 2011 (UTC)

You made a very definite assertion. I'm saying that it was almost completely unevidenced. It's not like you're saying "Many people have observed the Loch Ness, but no one has every produced evidence of a monster. It's safe to say that there is no monster." You're saying "No one has ever even been to Scotland, but we've got a dozen very low-res photographs, so There is no monster.". The first is a scientific statement, the second is not. You can't bluntly say that something doesn't exist because no one has produced evidence, if we haven't looked for that evidence! At that point you have to say that it's unknown.

Confusing the line between "Science is never 100% certain of anything." and "This particular thing is completely unknown" just gives fuel to the creationists and other anti-science types. APL (talk) 16:43, 21 April 2011 (UTC)

Agreed. As for the possibility of life on Venus now, if life can exist near hydrothermal vents at the bottom of our oceans, at extreme temperatures and pressures, then maybe it can on Venus too. Yes, the acidic environment of Venus is also harmful to life, but then so is free oxygen, yet life on Earth evolved to not only survive that, be to take advantage of it. And Venus does have a very reactive environment, with lots of energy available, which would promote both the creation of life and it's evolution. I have no problem imagining something similar to bacteria living on Venus. It may or may not exist, and I will make no definitive statement either way until I see some proof. StuRat (talk) 17:46, 21 April 2011 (UTC)

Here is what I remember having heard about venus. It is nearer to the sun and thus receives more solar energy than earth does. At times of the faint young sun this would have helped venus not to turn into a snowball. Venus is less massive than earth and I read somewhere (not on wikipedia, can't find it again now) that any planets less massive than earth cannot hold hydrogen by gravity. If so, venus, like mars, was bound to dry completely sooner or later. Venus does not have plate tectonics the way earth does. This way the exchange between the atmosphere and ground is limited. CO₂ would not be as dynamically released or bound geochemically like on earth. I think it was somewhere on wikipedia where I have read that the whole of the venus' surface was submerged in one single event. If so, there is no hope of ever finding any traces of life that may or may not have existed. 93.132.132.156 (talk) 22:11, 21 April 2011 (UTC)

I found part of the information here Geology of Venus#Global resurfacing event 93.132.132.156 (talk) 22:26, 21 April 2011 (UTC)

Bosch reaction

Is it endothermic or exothermic? --75.40.204.106 (talk) 02:16, 21 April 2011 (UTC)

According to the Wikipedia article Bosch reaction it is exothermic. You could check yourself with the data at Standard enthalpy change of formation (data table). --Jayron32 02:52, 21 April 2011 (UTC)

What would Earth be like if it was 82% more wonderful?

It's great that you're being creative and imaginative, but this isn't the correct place for it.
The following discussion has been closed. Please do not modify it.
I have collapsed this discussion. This is the science reference desk. On this page, we seek to improve the quality of our encyclopedia by helping people find scientific references. If you want help finding internet discussion forums or other outlets for your creative energies, you might find better answers on the Humanities or Miscellaneous desks. Nimur (talk) 04:21, 21 April 2011 (UTC) When people think of environments much better than those found on Earth, they invariably talk of Heaven and its variants, which are INCOMPARABLY better. Earth is amazing, wonderful, astonishing, charming, exciting and deep, but the world to which I refer is 82% more enhanced in all of these properties. What would such an Earth, one that is better but not incomparably better to the one we know be like? The immediate objection to this question will be that it is not “scientific” because the properties of “amazing, astonishing…etc” are subjective descriptions. This is so, but subjective evaluations can be quantified and measured by psychometric means. We don’t need to do that here; for the time being a respondent can estimate what features such a planet might have that would render it 82% more wonderful in every way to the one we live in. Not 100%, or 200%, but 82% - it is important that the last figure be the one under consideration, although respondents to this query might wish to compare their 82% ideal with what would be the case if the figure were much higher. For myself, I believe the following would be a reality in such an Earth: 1. There would be four sexes, male, female, devotrain and andila. Everyone would be male or female but also be either devotrain or andilian. A devotrainian male could make love to an andilian male without being homosexual. There would be an another entirely different kind of eroticism which would run parallel with the one we know. Human navels would become powerfully erotic organs which, when joined with another’s, would emanate fibres that would extend through the other’s body. When the moment of devotrainian or andilian orgams occurred, it would be felt from head to toe. 2. Humans would have eyes which, when properly trained upon the night sky for half an hour or so, can see the cosmos as clearly as the Hubble Telescope does now. Indeed, humans will be able to see in the infra red and unlta violet, and the brain will be hard wired to see two extra colours. 3. People will be able to glide for considerable distances, and death by falling will no longer occur. To fly like a bird, however, would require an Earth 128% better than the one we have. 4. There will be creatures like vast air ships, 10 times larger than the biggest whale, which will be tame and carry thousands of passengers across the seas in great comfort, requiring only some food and love. 5. The Earth will be 34% larger, but correspondingly less dense so that gravity is largely unaffected. There will be two extra continents. 6. We will share the planet with another species equal to our own in intelligence, and with whom we can communicate. 7. During the night when we sleep, we will be able to join in a universal dream in which all sleeping people of good will can partake, involving vast on-going dramas ranging from passionate love to intense adventure. Can you provide some more background for this world? Myles325a (talk) 02:54, 21 April 2011 (UTC) Wait, you've invented a fantasy world and now you want us to provide you with more information about it? The world is in your head. You can give it all the background information you want. The reference desks aren't really an appropriate place to try to write a crowdsourced science fiction novel. Do you have a specific factual question we can help you find answers to in Wikipedia articles? --Jayron32 02:59, 21 April 2011 (UTC) Op myles325a back live. Sigh...sigh...I DID say, above "The immediate objection to this question will be that it is not “scientific” because the properties of “amazing, astonishing…etc” are subjective descriptions. This is so, but subjective evaluations can be quantified and measured by psychometric means. We don’t need to do that here...". And so you go ahead and make exactly the same objection I had already tried to pre-empt. You very well might not agree with this pre-emption, but you could have at least acknowledged that I made it. A couple of other points. One: These questions are not just for people who can't use the Search function in WP. And two: It's not just IN my head. You are assuming that. The reality is more complicated. Myles325a (talk) 03:13, 21 April 2011 (UTC) You may be interested in Leibniz's 'Theodicy', which argues that we live in the best possible world (and hence it cannot be made 82% more wonderful). Or you may be interested in Voltaire's Candide, which was influenced by Leibniz's work, and largely ridicules this notion. SemanticMantis (talk) 03:15, 21 April 2011 (UTC) And no doubt this world has 82 percent more giant purple mushrooms.190.56.105.52 (talk) 04:01, 21 April 2011 (UTC) You realize you've basically described the movie Avatar right? Ariel. (talk) 04:09, 21 April 2011 (UTC) No ariel .I don't think Pandora had any giant air ship creatures that carried people across the seas in great comfort.190.56.105.52 (talk) 04:19, 21 April 2011 (UTC) OP myles325a back live. Thanks. You have ensured that everyone will want to see what has been censored by you, Nimur, just as surely as they will touch the wood where a sign says "wet paint". But I ask of these potential respondents. Please don't. Don't look at this question. It's just..not something you should see. I have conformed to the wishes of my betters. The question is now posed in the Humanities Board. Myles325a (talk) 05:14, 21 April 2011 (UTC)

Kindle 1 reflective scrolling — how does it work?

The first-generation Amazon Kindle has a visually fascinating way to select on-screen options. Above a scroll wheel is a long vertical grayish-white line which looks plastic or rubber. But as you turn the wheel, portions of this line suddenly become reflective, like a mirror — you can actually see (part of) yourself in it. The location of the reflective part tells you which line on the screen you'll select if you push the wheel down.

It looks like magic; even having owned this thing for a couple hours, I still can't wrap my mind around it. What exactly is it made of? How can something instantly go from "mirror" to solid gray/white? (To clarify, the line seems to respond to the computer input of the Kindle — it doesn't do anything if the Kindle is off, and larger or smaller portions of it become reflective based on the size of what is being selected.) ± Lenoxus (" *** ") 03:10, 21 April 2011 (UTC)

How is that any more "magical" than the rest of the screen where white turns into black (and shades of gray)?

I think the question is how the "mirror" works. (Normal pixels can't "mirror" -- presumably the e-ink allows for the use of reflective coloration, but I don't really know.) --Mr.98 (talk) 16:20, 21 April 2011 (UTC)

No, it's not e-ink. The "Cursor Bar" is not part of the main screen. It's a separate display next to the main screen that updates quickly like a normal LCD.

Except instead black/clear like a normal cheap LCD, the cells turn mirrored when they're on and clear when they're not on.

I have also wondered what kind of technology this is, and why they don't make digital watches with it. APL (talk) 16:51, 21 April 2011 (UTC)

[8] suggests it's as simple as an LCD with a mirror backing instead of a backlight. Nil Einne (talk) 17:06, 21 April 2011 (UTC)

That sounds plausible to me. It would make sense for a device that has no backlight — you'll need to have it in light of some sort anyway, so a mirror backing is a clever way to deal with the LCD lighting issue (like an old microscope). --Mr.98 (talk) 18:54, 21 April 2011 (UTC)

Thanks for the responses! I guess I'd never put much thought to exactly how a normal Liquid crystal display works either; it's pretty fascinating too. In reply to APL above, I would guess that a watch (or similar device, such as a calculator) which used "mirror" instead of black would be rather difficult to read. On the Kindle, you can simply tell that "stuff's there" on the LCD line; more detailed information would likely become difficult to parse, if it were mirror on gray. Although perhaps not mirror on black, come to think of it. I wonder why Amazon didn't go with that instead… ± Lenoxus (" *** ") 23:53, 21 April 2011 (UTC)

unknown herb

Hi, does anyone know the name of this herb: http://img816.imageshack.us/i/photo1jd.jpg/ 84.228.108.151 (talk) 11:24, 21 April 2011 (UTC)

Perhaps some variety of thyme? Note the the variety of thyme foliage, e.g. [9]. Aside from visual ID, you can taste / smell a few crushed leaves, and compare to any known herbs you may have in your kitchen. SemanticMantis (talk) 14:02, 21 April 2011 (UTC)

Looks more like a variety of mint to me. --ColinFine (talk) 16:13, 21 April 2011 (UTC)

Hard to tell from the picture, but mint (or something in the same family like basil or catnip) will have stems with square cross sections. That said, it looks very much like the pot of marjoram I have. (Marjoram smells something like a cross between thyme and oregano.) - Actually, following links tell me that thyme, marjoram, and oregano are also included in Lamiaceae, the mint family. Checking the pot, marjoram does indeed have a square stem cross section (only noticeable on the larger stems). -- 174.31.219.218 (talk) 16:27, 21 April 2011 (UTC)

Glow discharge creation

Whats the best way of creating a glow discharge betweem 2 parallel wires, and would it be better if one or both of the wires had a circular cross section?--92.29.203.164 (talk) 11:37, 21 April 2011 (UTC)

Besides the article you cited, see also Geissler tube and Neon sign. A glass vessel filled with low pressure gas of the appropriate sort and sufficient voltage (AC or DC) to produce ionization, with a resistor to prevent excess current when the gas starts to conduct, with airtight seal for the leads. The voltage to produce a discharge between electrodes decreases as the gas pressure is reduced down to some low pressure, below which the required voltage increases. A neon lamp presents a very high resistance until the voltage is high enough to ionize the gas. One demo was to have a high voltage battery in an RC circuit, which would gradually charge the cap until the conduction voltage was reached, at which point the neon light would flash. Do you have a vacuum pump and glassblowing equipment? I have pondered using a kitchen vacuum food preservation pump, with the plastic jars they supply, and sealing the electrodes through the lid with aquarium seal. This would not work for a long term use such as a a commercial neon sign, but might be ok for a demo or experiment. I would avoid using glass jars due to the danger of implosion and shards flying, and any high voltage has the potential to produce a dangerous shock. Old books on the subject suggest using mercury to pull a vacuum in the tube, which would be considered too dangerous for amateur experimentation now. A discharge tube under some circumstances might put out dangerous xrays, so home experimentation is not a good idea. An old reference on the subject is Townsend, "Electricity in Gases," (1915). The classic Geissler tubes used electrodes at either end of a cylinder or other shape of evacuated tube with a residue of gas. Your question was about parallel wires. We see that configuration in the common NE-2 neon lamp It ionized at about 90 volts. They can be used for lots of interesting projects. See [10] in particular.Edison (talk) 19:19, 21 April 2011 (UTC)

Oh, you're so punny... --Jayron32 19:51, 21 April 2011 (UTC)

I typed "potential" in all innocence and only on rereading noted the pun, so went ahead and bolded it. Edison (talk) 20:08, 21 April 2011 (UTC)

As for circular cross section: at least for high voltage conductors in air, a conductor with a large cross section and no sharp edges is less prone to cause ionization of the gas molecules in the air, and less corona discharge. For a gas discharge tube, the same is likely to be true. I would expect parallel small diameter wires to cause ionization of the trace gas at a lower voltage than larger radius conductors the same distance apart. A sharp edge might concentrate the current and cause more local heating if the current is larger. This is just my expectation, and I have not found a reference on it. Edison (talk) 00:20, 22 April 2011 (UTC)

Where have the "edit" buttons per section gone?

Normally there should be an "[edit]" button with each section. I don't see any any more. I have reloaded about 10 times now. What's wrong? 93.132.132.156 (talk) 21:37, 21 April 2011 (UTC)

They're right where they've always been for me. But I don't see how this is a science question... Dismas|^(talk) 21:39, 21 April 2011 (UTC)

Because I missed them here on this desk, I posed the question here. Why should this not be a science question? is computer science less a science? 93.132.132.156 (talk) 21:43, 21 April 2011 (UTC)

Normally computing questions go on the computing desk. But then again, normally questions about how Wikipedia works should go at the Help Desk. Anyway, it's possible that your CSS or something got messed up, or what Wikipedia just had a hiccup for you. If it's better now, I wouldn't worry about it. --Mr.98 (talk) 22:32, 21 April 2011 (UTC)

(ec) And now I have edit buttons. Do I have to ask a question first in order to see them? Doesn't make much sense. And I haven't altered anything with my browser or computer lately. 93.132.132.156 (talk) 21:43, 21 April 2011 (UTC)

Usually when that happens to me, I'm actually looking at a version from the page history. Those have a notice at the top that you're editing an old version, but on a long page like this you never notice. Wnt (talk) 22:34, 21 April 2011 (UTC)

At the top of the page, did you see the 'edit' tab or a 'view source' tab? If it's the later, it's been discussed before on the talk page and I've encountered it myself that for some strange reason the page appears as protected for anonymous users even though it was never (semi-)protected. Note that when reloading a page you should always try WP:BYC and probably even WP:PURGE since reloading 10 times is no use if your browser or the wikipedia servers just keep sending you the same cached content Nil Einne (talk) 23:54, 21 April 2011 (UTC)

It looks like a case for WP:PURGE. I saw 'view source' instead of 'edit' at the top. After I asked this question (instead of a null edit) it went away. Perhaps you know a workaround for yet another plague: lately some of the formulas display with an incomplete (west north) border that gives the impression of a square root. 95.112.196.91 (talk) 14:31, 22 April 2011 (UTC)

Cookie Monster ate them. Count Iblis (talk) 22:52, 21 April 2011 (UTC)

Same thing happened to me man. All the edit links are gone! When I logged in, they appeared, so this must be part of the movement to disenfranchise anonymous editors. Mac Davis (talk) 01:32, 22 April 2011 (UTC)

"Semi-protection" might do that for other pages, but the Science Refdesk isn't semi-protected, and according to the logs it hasn't been semi-protected, at least not any time this year. Wnt (talk) 06:47, 22 April 2011 (UTC)

See my comment above or check out the latest RD archive. Nil Einne (talk) 14:15, 22 April 2011 (UTC)

Digital signals in space

Analogue signals are broadcast out into space, and any aliens out there within 60 light years will be receiving them and can see/hear what we are like!:

1. would an alien civilisation be able to see/hear them in the same way as they could with the analogue signals, or would they not be able to decipher them?

I looked around for an answer but couldn't find any, so I hope someone can answer this for me!

Regards, -- PhantomSteve.alt/talk\^{[alternative account of Phantomsteve]} 23:18, 21 April 2011 (UTC)

The answer to #1 is unambiguously yes. We can't stop electomagnetic signals generated on Earth from leaving the Earth. However, this signal tends to degrade over time, due to two things: attenuation and the inverse square law which basically states that as a signal travels over space, it "spreads out" and becomes gradually weaker to the point where it becomes so weak it disappears. The answer to #2 is that we're not even sure that an alien civilisation would be able to decode our analogue signals. In the novel and film Contact, an alien civilization beams some our own TV signals back at us. There is, however, no need for them to have decoded them; they could just have reflected the signals back at us. However, given point #1 I made above, its not readily clear that any signals that have been generated at earth would even make it to the nearest star, let alone be able to be decoded... --Jayron32 23:27, 21 April 2011 (UTC)

While it's impossible to know how aliens will think, I'd bet they can make sense out of an analog TV signal. The signal, after all, consists of raster lines which are similar from one to the next, yet differ... before long, they're putting them side by side and realizing it makes an image. They might not know which color is which - yet I'd give them even credit for that, because the observant alien will see occasional rainbow icons and substances such as magma that can only come in certain colors on any planet. I would likewise give them good odds of making sense out of a digital signal because it can be worked over to produce recognizable patterns. I don't know if they'll work out the AACS key, but I wouldn't put it past them. ;) Wnt (talk) 23:52, 21 April 2011 (UTC)

Is that for when they land and take away some Blurays? AACS isn't used in broadcast television or anything but Blurays and the now defunct HD-DVDs AFAIK. Of course smarters aliens would just find it online. Nil Einne (talk) 00:01, 22 April 2011 (UTC)

They probably have a radio telescope made from a network of single-atom filaments, the size of the solar system. It zeroes in and logs every time Earthlings make a cell phone call, play a video, type anything that appears on a computer screen that isn't secured against Van Eck phreaking, or talk somewhere in the open within a hundred yards of a power line. They're supposed to be advanced - they're aliens. And how do you think they made this simulation you're enjoying now if they couldn't properly spy on EM signals? Wnt (talk) 06:53, 22 April 2011 (UTC)

That aliens would be able to figure out that analog TV signals, when arranged a certain way make images than can be "seen" assumes that aliens have vision and are able to see images like we do. Vision is not uncommon for Earthly species, but even here there are alternate ways of "seeing"--like echolocation. For all we know the first aliens to intercept Earthly TV signals live gas giants and "see" via magnetic fields or something similarly unlike human vision. Or perhaps they "see" some aspect of reality we don't even know exists and can't perceive light at all. The idea of aliens with eyes similar to ours strikes me as very unlikely. Seems they'd be as likely to know about Jesus Christ and hot dogs. Perhaps intelligent aliens capable of abstract thought might recognize TV signals as a curious pattern, and perhaps could figure out how to decode the signal into what we would call images. But it seems to me a huge assumption to think they would "see" the images in a way that made any sense, if they could "see" at all. The common stereotypical "alien" we picture is ridiculous anthropomorphic. I wouldn't be surprised if there are sentient aliens out there, but I would be very surprised if they were remotely similar to us--that we would even be able to recognize them as sentient beings at all (and vice versa). Even on our planet we have trouble recognizing sentience or lack thereof among birds, cetaceans, etc etc etc. Pfly (talk) 09:52, 22 April 2011 (UTC)

The eye has evolved almost from scratch many times on Earth. The mammalian eye, the cephalopod eye, the insect compound eye and numerous others each evolved separately (our common ancestor may have had some kind of light sensitive cells, but not a specific eye). That suggests an extremely strong and near-universal selection pressure toward vision. If so many different animals have evolved eyes on Earth, it is highly likely that any life-as-we-know-it on other planets will have eyes too. (Life-as-we-don't-know-it is a very different kettle of fish, and not one we can have any useful discussions about. We just don't have a starting point to understand how such life would work.) --Tango (talk) 13:48, 22 April 2011 (UTC)

As others have mentioned, typical early TV signals will be quite weak by now, but we have occasionally sent radio messages into space at much higher power, with the explicit intent of catching someone's attention. See e.g. the Arecibo_message. Note that in this message, as in the Voyager_Golden_Record, scientists have taken great care to encode the message in terms that are thought to be fairly universal. SemanticMantis (talk) 01:23, 22 April 2011 (UTC)

I would be very surprised if a human seeing the Arecibo message in isolation would be able to interpret it. It's just looks cool. That was the whole purpose of it. If it was actually intended to catch someone's attention, they would have made it much simpler and send it towards a nearby yellow dwarf star. Instead, they made it very complicated and sent it towards a very distant cluster. As our article says, it was just a demonstration of their cool new toy, not a real attempt at making contact with aliens. --Tango (talk) 13:48, 22 April 2011 (UTC)

But by sending it to M13, the signal arrives at all the few hundred thousand stars it is composed of. Count Iblis (talk) 14:54, 22 April 2011 (UTC)

That would be true if they had sent it to M13. They actually sent to where M13 was 25,000 years ago. They should have sent it to where M13 will be in 25,000 years time. Our articles explains this (with references to official press releases - they were perfectly open about the whole thing). --Tango (talk) 15:30, 22 April 2011 (UTC)

I see! This looks rather stupid :) . In Ref 1. where that fact is mentioned it is also clamied that the signal could still be received with similar equipment in M31. If that were to happen, ET would also get the message of just how stupid we are :) . Count Iblis (talk) 16:10, 22 April 2011 (UTC)

Yes, I agree it would be difficult for any single human to decode, and that it was a somewhat symbolic gesture (voyager record even more so). However, if the Arecibo message were given to a room of scientists that were well-educated (but ignorant of this message), I think they could decode it, given a little time and motivation. I believe decoding the Arecibo message or Voyager record would be easier than decoding a TV signal (assuming you could find the properly educated group of scientists with no prior knowledge), but this is potentially debatable. SemanticMantis (talk) 15:17, 22 April 2011 (UTC)

The issue is whether there is a single interpretation that makes more sense that any other. Figuring out the binary should be easy enough, but then why would you interpret the numbers as atomic numbers of elements rather than any number of other things? With a TV signal, there's really only one interpretation that makes sense. It may take a while to stumble across it, but once you have you'll know you've got it right. --Tango (talk) 15:30, 22 April 2011 (UTC)

Advanced civilizations will likely be machine civilizations. Now, intelligent machines can travel at the speed of light, simply by uploading themselves via electromagnetic signals to another machine. That's easy to do within one civilization, but then they can only travel to locations where they have build their machines. However, by contacting distant civilizations, they can travel to those civilizations, if these civilizations are able to download and run the code of the machines.

So, you can imagine that a civilization sends a simple message to catch the attention of other civilizations and then that message is followed by a message containing a schematic outline of a machine so that it is clear how a machine code is to be interpreted. Then the entire code of a machine is sent. This whole sequence of sending the simple message, the message containing information on how to interpret the code and then the code itself is then repeated over and over again.

Civilizations that receive this message do not send a reply, as no reply is expected. All they have to do is build a suitable machine, download the code and run it on the machine. Count Iblis (talk) 16:59, 22 April 2011 (UTC)

What do you mean by "machine"? Any lifeform is a machine, in a sense, but I don't see any reason why organic life forms can't form an advanced civilisation. The idea of mind uploading for interstellar travel isn't a new one, but trying to give instructions on how to build the receiving device to a completely alien civilisation by remote (especially without two-way communication) seems ridiculously difficult to me. --Tango (talk) 19:22, 22 April 2011 (UTC)

Consider our own future. The free market economy has a natural end point. When all human involvement in all production processes from raw materials to finished end product is fully automized, everything will be free of charge (while labor cost only form part of the costs of a product, the costs of raw materials, energy etc. are ultimately also due to labor costs.). In that end state you'll have humans living in a planned economy. Free enterprise will be outlawed, because you don't want out of control growth of machines, like in the grey goo-scenario. Humans are then more or less barred from doing anything productive. Only an elite will be in control of things. But that elite will find it more and more difficult to control things as the civilization becomes more complex.

As the machines get more complicated, the elite need ever more intelligent machines to control things, but then these intelligent machines will, at some point, be so much more intelligent than humans, that the elite won't really control anything at all. Humans will then be prisoners of the machines, much like most animals on Earth are now. Freedom is only tolerated up to a point: as soon as a wild animal interferes with our civilization (e.g. when a lion shows up in a city, claiming the teritory there, we remove the lion). Count Iblis (talk) 20:41, 22 April 2011 (UTC)

You seem to have forgotten about the service economy. In the developed world, agriculture and industry are becoming smaller and smaller portions of the economy and more and more people work in providing services to others, not producing physical things. As some services become automated or obsolete, others become common. That's the trend that's been going on for the last 100 years and I see now reason why it won't continue. --Tango (talk) 21:09, 22 April 2011 (UTC)

You're all making great points, but isn't this straying into forum/soapbox/opinion? Are you editors any longer contributing to a cogent answer to the OP, or just musing now? Franamax (talk) 22:06, 22 April 2011 (UTC)

April 22

What's the species?

Hi. Could someone help me in finding the species of this lizard? I took this photograph last week at the Horton Plains National Park, somewhere near the summit of the Kirigalpoththa mountain, in Sri Lanka. Rehman 01:39, 22 April 2011 (UTC)

Claiming no expertise in this at all, I looked at "Reptiles of Sri Lanka" and decided it looked like one of the Agamidae and not the other groups they list (I was assuming since this is a tourist snap that it's not a very rare species). Among the Agamidae are horned lizards Ceratophora. Searching for these, I found a "Ceratophora stoddartii" (last photo at [11]) which looks a lot like yours to my eye. Caveat: most of the images on a Google image search for this species don't look much like it and are all different colors. I've made no attempt to determine if that is chameleonlike change of color, genetic variation, iridescence, etc. Wnt (talk) 06:43, 22 April 2011 (UTC)

Thanks! After referring to srilankanreptiles.com you mentioned above, I am pretty sure it is the Rhino-horned lizard. Thanks again. Regards. Rehman 07:45, 22 April 2011 (UTC)

potentiometer question

Can a potentiometer that is designed for a tone control (i.e. bass or treble) work properly when used for a regular volume control? Bubba73 ^{You talkin' to me?} 05:25, 22 April 2011 (UTC)

Perhaps. The replacement potentiometer must of course have the same max resistance as the original pot. The wattage rating also has to be high enough, but that’s probably not going to be a problem.

Looking around at a few tone control circuits, I see that the first couple I looked at at least called for linear taper pots. In contrast, pots used for volume control, at least in more expensive devices, are sometimes logarithmic taper. But the difference isn't all that big of a deal; using a linear taper pot where a log taper pot is called for just means that there'll be a bigger perceived change in volume for the same angle change at one end of the dial than the other. But cheap devices generally go ahead and use the cheaper linear taper pots for volume control anyway, so the difference between a linear taper pot and a log taper pot really isn't anywhere near as important as just making sure the replacement pot has the same max resistance as the original pot.

There are a couple contributors here who can run circles around me at EE, so if anybody pipes in to disagree with what I've said above, listen to them instead of me. Red Act (talk) 07:29, 22 April 2011 (UTC)

ELECTRONICS

How an FM transmitter & receiver is designed27.97.64.66 (talk) 08:32, 22 April 2011 (UTC)

They are rather complicated. Have you read transmitter and receiver? Those articles will get you started.--Shantavira|^{feed me} 11:24, 22 April 2011 (UTC)

I feel the OP is more interested in some kind of circuit diagram, something like that. As wikipedia is not a HOWTO, such things are only found externally. 95.112.196.91 (talk) 13:17, 22 April 2011 (UTC)

marsh plant that needs pressure from flowing water to hold structure?

Has anyone heard about such a plant? A friend told me about it years ago - maybe from the northern parts of Australia? - she described it as having a porous or open lower end - the water flows up into it and gives it structure through hydrostatic pressure... Can someone name the plant for me? Thanks Adambrowne666 (talk) 10:00, 22 April 2011 (UTC)

Indian Thundershowers

Does anyone know why Southern India gets thunderstorms during April, but normal showers during Monsoon (July-October)? Yes Michael? •^Talk 11:41, 22 April 2011 (UTC)

What does the word "Pinkie" mean?

The word "Pinkie" is used in terms like "Pinkie finger" and "Pinkie blue"? What is the meaning of the word "Pinkie"? aniketnik 12:06, 22 April 2011 (UTC) — Preceding unsigned comment added by Aniketnik (talk • contribs)

The "pinky" or "pinkie" is the little finger. Gandalf61 (talk) 12:11, 22 April 2011 (UTC)

If you follow the little finger link, you'll find that the "pinky" in "pinky finger" is listed as being from the Dutch word pink, ultimately from a Proto-Indo-European word for "five", "finger". Note that this seems to be unrelated to "pink", the word for the color, as that is listed as being derived from "pinks", a name for Dianthus (carnations), a name referring to the frilled edge of the flower and probably deriving from the German "pinken", to peck. This latter meaning is also seen in the name "pinking shears". -- 174.31.219.218 (talk) 15:41, 22 April 2011 (UTC)

From Wiktionary it's apparent this root also leads to finger, cinco, quintet etc. Wnt (talk) 21:02, 22 April 2011 (UTC)

What connections should scientists explore?

How do scientists decide which variable could correlate? If some crackpot theorist claims that certain stones cure cancer, should scientists go on and test it empirically? Should scientists dismiss intuitively some claims? Quest09 (talk) 13:29, 22 April 2011 (UTC)

In an ideal world, scientists would test everything (with a few exceptions due to ethical concerns, perhaps). In the real world, there are limited resources so scientists test those things that they think are most likely to give an interesting result (of course, what's interesting to a scientist isn't necessary what would be interesting to everybody else!). For medicine in particular, the normal route is to test things in Petri dishes first, which is fairly easy so they can test all kinds of things, and then only test on real people those things that showed promise in the Petri dish. So, they may well test stones on cancer cells in a Petri dish, but unless they actually seemed to work, they wouldn't test them on people. --Tango (talk) 13:57, 22 April 2011 (UTC)

I could play devil's advocate for a moment and note that some therapies – particularly non-drug interventions – are not always amenable to in vitro testing. While I would be unsurprised to discover that therapeutic touch and magic rocks have no ability to slow the growth of malignant cells in culture, I have to admit that it's also difficult to maintain a regimen of healthy diet and aerobic exercise in a petri dish.

Testing a novel protocol in humans depends primarily on three things. First, you need to find a researcher who wants to do the trial; often that means that they believe the trial will work, but someone who's genuinely curious or who is interested in debunking a bad idea will do. Second, you need to be able to get ethics approval to carry out the trial. An ethical clinician can't and won't participate in a trial if they have a reasonable expectation that the experimental therapy will have a worse outcome than the current therapy (see also clinical equipoise). Third, you need to have the resources – trained medical personnel, equipment, magic rocks, and most importantly, willing and informed patient participants – to carry out the trial. In general, this means it is impossible to do a trial of magic rocks versus chemotherapy, because the experimental therapy isn't supported by any evidence and is likely to kill patients. On the other hand, one might be able to do a trial of magic rocks plus chemo versus chemo alone (or, better, chemo plus blinded 'placebo' rocks); the worst-case scenario is anticipated to be that the rocks are ineffective, so the patients do no worse than with chemo alone. The hard part is finding resources to do the trial, since there are many more plausible treatments ahead of the magic rocks in the queue for funding. TenOfAllTrades(talk) 15:29, 22 April 2011 (UTC)

A problem with doing not well motivated tests is that this tends to lead to a bias where only positive results are reported. Suppose you have good theoretical reasons to believe that X may cause Y (but it is not clear that this must be the case). Then you investigate this and you find that in fact X doies not cause Y. This result is then still interesting enough for peer reviewed journals to publish.

But without any good reason to believe that X may cause Y, a negative result wont merit publication in a peer reviewed journal. Now, suppose that in such a case, you find a positive result at 95% significance level and that in reality this is due to chance alone (so no relation exists and you just happen to be in the 1/20 of cases where you find a significant result). Then that is likely to yield a publication in a peer reviewed journal. Certainly, it is now interesting for other researchers to see if X really does cause Y. But this may take time, and all that the public hears is that: "researchers have found that X causes Y". Also, onses the results come in that debunk the relation, these don't make headline news.

This effect is partially to blame for the paranoia about mobile phones causing cancer, mobile phone relay transmitters near building being involved in all sorts of illnesses, GM foods possibly not being safe etc. etc. etc. Count Iblis (talk) 14:47, 22 April 2011 (UTC)

As usual, there is an all-too-close-to-reality xkcd on this topic. Don't forget to read the mouseover text. TenOfAllTrades(talk) 14:54, 22 April 2011 (UTC)

And for a more serious treatment, see also publication bias, including the bit about the 'file drawer effect'. TenOfAllTrades(talk) 14:56, 22 April 2011 (UTC)

There is no one prescription that describes how scientists do or should approach the question of what areas would be fruitful or interesting. In practice it is almost certainly about who is willing to fund what — all of these things cost money, and finding creative ways to justify a project to a sponsor is a full-time occupation of many PIs. Even the philosophers of science who believe in strict demarcation, like Karl Popper, do not believe that you can apply that kind of criteria to the sources of inspiration or interest, which are often haphazard (e.g., at the extreme end, dreams, hallucinations, falling fruit). The question is perhaps more systematically stated as to what studies should be funded — which is a trickier question that balances likelihood of success, benefits from success, reputation of researcher, things like that. --Mr.98 (talk) 15:40, 22 April 2011 (UTC)

What do you mean by "success"? A study that shows a null result conclusively is just as successful as one that shows a positive result conclusively, in my opinion. --Tango (talk) 16:31, 22 April 2011 (UTC)

Scientifically, yes, but economically, no. That is, most studies are funded in the hope of eventually making money off them. Finding that a (patentable) drug works well may lead to economic success, while finding that one doesn't work isn't as likely to do so. The economics behind science can lead to both a poor choice of studies and, even worse, biased results. Finding a neutral source of funding is difficult, though. Government funding (from taxpayer dollars) of university research may be less profit-motivated, and thus allow studies of things like herbal remedies and traditional Chinese medicine, where profit potential is limited. Political considerations may come into play there, though, such as prohibiting any research on the benefits of stem cells. Use of charitable donations is another option, but major contributors may also have agendas they wish to purse. StuRat (talk) 19:22, 22 April 2011 (UTC)

Proving, based on currently accepted principles, that something (say, a perpetuum mobile) is impossible saves a real lot of money and effort. The major back-draw is that the poor guy who publishes such a result gets nothing in return but the hatred of those who hoped for funds for investigation and building one. 95.112.196.91 (talk) 20:45, 22 April 2011 (UTC)

"Success" would be defined differently in different contexts. I'm not trying to claim one standard for it. Proving a null result conclusively is only "successful" in some contexts, not all. Proving that unicorns don't exist on the moon conclusively would do little to benefit scientific knowledge. Proving that there is no luminiferous aether in the early 20th century did. --Mr.98 (talk) 20:48, 22 April 2011 (UTC)

Reaction Gone Wrong

Hello. When I mix KI, HCl, and starch, my solution turns blue without adding any KIO₃. Why? Thanks in advance. --Mayfare (talk) 15:33, 22 April 2011 (UTC)

Are you sure your original KI was pure enough not to contain any I₂ impurities? 95.112.196.91 (talk) 15:49, 22 April 2011 (UTC)

The KI is pure enough not to contain any I₂. --Mayfare (talk) 20:40, 22 April 2011 (UTC)

Potassium iodide in the first paragraph states that "Aged and impure samples are yellow because of aerial oxidation of the iodide to iodine". Did you try your KI to the starch without HCl? I have no idea how sensitive the starch test is but I remember my wild days when I did some testing for iron and always got false positive until I found out that the test is so sensitive that it gives positive results on the little iron that is contained in the tap water used. 95.112.196.91 (talk) 20:53, 22 April 2011 (UTC)

can a relativistic proton change into a neutron? or break up into various particles?

Are these processes possible? They seem possible to me, if the proton has enough energy ... but can kinetic energy transfer into the weak or the strong interactions?

1. highly energised proton ---> neutron + positron + e-antineutrino
2. neutrino + highly energised proton ---> neutron + positron
3. proton ----> pion+ + positron + electron

John Riemann Soong (talk) 17:41, 22 April 2011 (UTC)

The principle of relativity implies that the internal structure of the proton does not change when the proton is moving. Just imagine the situation from the point of view of the proton: the proton thinks that it is at rest and that you are moving. Since there is no absolute motion there is no absolute "energisation" through kinetic energy and the proton doesn't care whether its moving in your frame of reference or not; if it doesn't decay in its own reference frame, it will not decay in yours either. --Wrongfilter (talk) 17:56, 22 April 2011 (UTC)

Why is this different for electron states then? The kinetic energy of a reactant is important in whether it overcomes a barrioer or not, e.g. there's a transition temperature in which singlet oxygen will be the dominant species over triplet oxygen. -- John Riemann Soong (talk) 21:25, 22 April 2011 (UTC)

I've taken the liberty of formatting your question so it renders properly. (Line-breaks are ignored in wiki-syntax). #1 is Positron emission; #2 is beta decay, with the anti-neutrino written "backwards," and I don't recognize #3. Nimur (talk) 18:26, 22 April 2011 (UTC)

Positron emission and beta (plus) decay are the same thing. 1 and 2 are the same formula, except that 2 assumes the existence of a neutrino that annihilates the antineutrino. 3 looks like nonsense to me. The positron and electron can just annihilate each other, so you have a proton changing into a pion+, which is equivalent to an up quark and a down quark changing into a single anti-down quark. I can't see any reason to believe that could ever happen. --Tango (talk) 18:49, 22 April 2011 (UTC)

Your first two reactions don't conserve lepton number. You can fix that by swapping the antineutrino with the neutrino.

The first reaction (decay) can't happen because the principle of relativity says it's physically the same as the decay of a proton at rest. In the second case the frame-independent properties of the input include a single relative velocity, and the reaction can happen if that is large enough.

Your third reaction (decay) isn't prevented by conservation of energy, because the total rest mass of a pion and two electrons is smaller than the proton rest mass. But it doesn't conserve baryon number, and more strongly, it doesn't conserve B − L. Decays that change the baryon number but not B−L, such as
p⁺
→
π⁺
+
ν
_e, are allowed by grand unified theories but have never been observed. In any case, the proton's speed makes no difference, because these theories still obey the principle of relativity. -- BenRG (talk) 21:28, 22 April 2011 (UTC)

What about the case of electronic transitions? Can't a highly kinetically energised hydrogen atom excite its shell electron? (Isn't that what happens in a plasma?) How is this different from an energetic proton exciting one of its quarks? Also, isn't it possible under a strong electric or gravitational field, to breakup a moving nucleus or a moving nucleon by tidal forces? John Riemann Soong (talk) 22:15, 22 April 2011 (UTC)

You're right, a proton excited state can decay to neutron + positron + neutrino. We all assumed you were talking about overall kinetic energy of the proton. This decay is probably also possible in a background electromagnetic field, although additional particles are involved then, so it's not exactly a decay. I see no reason why gravitational tidal forces couldn't break a proton apart, but that's not an experiment we can do, and nobody really understands quantum gravity. -- BenRG (talk) 23:12, 22 April 2011 (UTC)

But in electronic transitions, mere temperature alone provides the kinetic energy that supplies the activation energy to excite an excited electronic state. John Riemann Soong (talk) 06:35, 23 April 2011 (UTC)

What kind of flowering tree?

I took this photo on 10 April at 39°48′44″N 86°12′9″W. Can anyone identify the species of the trees in this picture? All I can guess is that they're way too big for apples or cherries, and definitely the wrong shape and size and color for redbuds; I don't know what any other kind of tree flower looks like. Nyttend (talk) 19:57, 22 April 2011 (UTC)

I'm guessing dogwood. Looie496 (talk) 20:11, 22 April 2011 (UTC)

Dogwoods tend to be more rounded or slightly flattened. I think it might be a fastigiate pear like this. Obviously the trees are much older than the example, as one can see from the bark which has the cracked and flaky appearance of an old pear tree. Richard Avery (talk) 21:51, 22 April 2011 (UTC)

The species that you linked as "this" is Callery Pear, which sounds right: it's one of the most common ornamental trees in North America. Thanks for the help. Nyttend (talk) 23:03, 22 April 2011 (UTC)

Ornamental pears are excedingly common in the U.S. because they are super cheap and super fast growing, so builders often put them in all over the place. My neighborhood has one in front of just about every house. It would not be uncommon at all. Callery pears, cited above, are often called "Bradford Pears" or "Cleveland Pears" in the U.S., and have a distinctive odor when in bloom, reminiscient of ammonia or old fish; if you've got hundreds in one area it can be overwhelming. --Jayron32 02:44, 23 April 2011 (UTC)

Fission2

I asked a question about binding energy above and now am more confused than before, and feel like an idiot. Please explain the defect in my understanding:

In the nuclear fission of uranium, about 1/10th of 1% of the mass of the nucleus is converted to energy. (I added this information myself in this edit, quoting a 1950 article from the Bulletin of the Atomic Scientists.) That's super. However, our binding energy article, our nuclear fission article, our E=mc2 article, and the responses of knowledgeable editors to my previous question all agree that the masses of the fission products add up to a higher mass than the mass of the original uranium atom.

Some crucial part of this is clearly sailing about a foot above my head. If a uranium atom is in an imaginary box and the atom fissions, and the resulting gamma rays are allowed to escape the box but the fission products (say, krypton and barium) stay in the box, the contents of that box must be lighter, by the mass of the gamma rays. But, contradicting this understanding, all the information above informs me that the krypton and barium have a greater mass combined than the original uranium atom. The box is now heavier. Huh?

Your idiot,

Comet Tuttle (talk) 21:15, 22 April 2011 (UTC)

To give an example ²³⁵U + n -> ⁹²Kr + ¹⁴¹Ba + 3 n.

I get that the rest masses in amu are 235.044 + 1.009 -> 91.926 + 140.914 + 3*1.009

Which gives 236.053 -> 235.867, a mass loss of 0.186 amu (0.08% of the initial uranium mass).

Does that clarify things? Dragons flight (talk) 21:37, 22 April 2011 (UTC)

Yes; this is great; but see below. Comet Tuttle (talk) 22:08, 22 April 2011 (UTC)

If energy is released by a reaction then the total rest mass of the products is smaller than the total rest mass of the inputs; you're quite right about that. I don't think anybody said otherwise in the previous thread. It's confusing because of inconsistent use of the word "smaller" with negative numbers, as I said there. (But rest masses are never negative, so there's no ambiguity in what I said here.) -- BenRG (talk) 21:44, 22 April 2011 (UTC)

TenOfAllTrades wrote: "the atomic nucleus will always have a slightly lower mass than the sum of the masses of its constituent particles." (I'm not challenging him or her here because the same thing is echoed in the articles I cited above in this thread.) Wouldn't that mean atomic fission is endothermic, contradicting my imaginary box mass statements and reality? Comet Tuttle (talk) 22:08, 22 April 2011 (UTC)

Those "constituent particles" are the nucleons. Splitting a nucleus into individual nucleons does always consume energy (unless it's ¹H); therefore, creating a nucleus from nucleons releases energy. If you build two smaller nuclei using nucleons obtained from a big nucleus, you may release more energy than you spent breaking the larger nucleus apart. -- BenRG (talk) 22:24, 22 April 2011 (UTC)

Ahhhhhh! — so in Binding energy, in the line stating "Classically a bound system is at a lower energy level than its unbound constituents, its mass must be less than the total mass of its unbound constituents", by "constituents" it means to say "individual nucleons"? I had taken "constituents" to mean "any combination of smaller nuclei", so a barium nucleus and a krypton nucleus would count as "constituents" of the uranium nucleus and when added up, their masses had to add up to be greater than the uranium nucleus's mass. Comet Tuttle (talk) 22:46, 22 April 2011 (UTC)

Yep, that's the ticket. The binding energy is calculated relative to the completely disassembled nucleus: individual, separated protons and neutrons. TenOfAllTrades(talk) 23:25, 22 April 2011 (UTC)

"Individual nucleons" would be too narrow a definition of "constituents" to use in the binding energy article. In fact, I disagree with the sentence you quoted. It may be true when you take "constituents" to mean "nucleons", but there's no deep reason why it has to be true even in that case. In quantum mechanics, any system that can decay into components with a lower total rest mass will eventually do so, but the decay half life can be extremely large, like 10²⁰ years or more. Even a free neutron's 15-minute half life is incredibly long compared to the usual time scale of nuclear physics, which is attoseconds or less. It's reasonable to call these bound systems, and physicists do call them that. -- BenRG (talk) 05:22, 23 April 2011 (UTC)

I don't see that it's unreasonable to consider the individual nucleons as the specific "constituents" of a nucleus. If one were to ask what a uranium nucleus' constituents were, one would not expect 'krypton and barium nuclei, of course' as a response. The heavy nucleus doesn't exist with smaller nuclei as independent bound components within it. (Similarly, one wouldn't say that the "constituents" of trees are framing lumber, tongue depressors, and sawdust, even though those could be one valid set of 'fission products'.) TenOfAllTrades(talk) 17:24, 23 April 2011 (UTC)

Nuclear binding energy is positive when you look at when nuclei are built up, say, when energy is released by p-p fusion in the sun. But it is negative in the sense that when you look at the resulting nucleus you get, this energy has gone away, and the net mass of the complete nucleus is lower than the net mass of the protons and neutrons that went into it. You can't split the nucleus back up again - at least, not all the way back to protons and neutrons - without getting energy from somewhere. This is true for any element (except ¹H...) because if the binding energy were positive, the nucleus could emit energy as it blew itself apart, and there would be no barrier to doing so. (Well, the extended periodic table talks about elements over maybe 173 that can't exist, but we haven't seen those. ;) )

April 23

Ibuprofen structure

What does the squiggly bond mean?

--75.40.204.106 (talk) 01:42, 23 April 2011 (UTC)

This is depicted in our article but that specific symbol depicts a bond that extends away from the observer. In this case, it is a bond linking a carbon adjacent to a carbonyl group (at right) and a methyl group represented by the end of that "squiggly" line (by convention, hydrogen atoms bound to carbon atoms are not shown). So, that methyl group is farther from the observer than the carbon to which it is attached. -- Scray (talk) 02:30, 23 April 2011 (UTC)

Actually, the squigly bond means that the structure is racemic. If the methyl group were going away from the viewer, it would be a "dashed" bond. A "wedge" bond is going towards the viewer. Racemic means that the actual medicine is a 50/50 mixture of both forms of the molecules. If the line is supposed to mean that it is going away, whoever created the picture used the wrong line. --Jayron32 02:36, 23 April 2011 (UTC)

Thanks for correcting me, Jayron32 - I was careless, thinking of the dashed bond! -- Scray (talk) 03:21, 23 April 2011 (UTC)

The main article about interpretting all the details of this sort of diagam is "Skeletal formula". DMacks (talk) 14:25, 23 April 2011 (UTC)

Perspiration

Why do some men of the same build and age, sweat more than others? —Preceding unsigned comment added by 74.100.193.38 (talk) 01:43, 23 April 2011 (UTC)

For the exact same reason that some men of the same build and age have different sounding voices or different colored eyes. The Wikipedia article titled Perspiration covers the process in more detail, as well as covering various conditions that can lead to increased or decreased perspiration. --Jayron32 02:40, 23 April 2011 (UTC)

how to pass entrance

SIR I AM A STUDENT OF 12 CLASS,HAVING SCIENCE ,OUGHT TO JOIN MEDICAL FIELD, MANY PEOPLE SAYS THAT IT IS DIFFICULT TO CLEAR THE ENTRENCE EXAM THEN WHAT SHOULD I HAVE TO DO. I M BELOGING TO NORMAL FAMILY HENCE CANT BE ABLE TO PAY LOTS OF COLLEGE FEE, i ought to join goverment college then what 2 do? PLEASE GUIDE ME I WILL PAY MY 100% TOWARDS UR ADVICE.... —Preceding unsigned comment added by 223.189.23.145 (talk) 02:47, 23 April 2011 (UTC)

• You need to tell us in what country you are interested in becoming a certified medical professional, and you would also need to say which medical job you want. After all, an American nurse is going to have a very different set of ceretifications and training than a Russian dentist is, and both will be very different from a South African doctor. Its literally impossible to answer your question without knowing where you are from and what your career aspirations are. --Jayron32 02:59, 23 April 2011 (UTC)

The IP geolocates to India.[12] Red Act (talk) 03:50, 23 April 2011 (UTC)

As a rule of thumb, an OP that addresses us as "Sir" is probably Indian. It's nice to be shown a little respect, rather than the insults and demands we get from some of our OPs! --Tango (talk) 13:09, 23 April 2011 (UTC)

To the original querant: It might help you to arrange a meeting with a local medical professional, to discuss options with them. If they take an interest they may be able to help you. You might also see whether they would allow you to work in their clinic. The experience with them may be very educational - in a practical way. -- Scray (talk) 03:25, 23 April 2011 (UTC)

Medical usually means Medicine.Curb Chain (talk) 11:33, 23 April 2011 (UTC)

Of course it does, but that doesn't necessary mean a doctor. The term can be used more generally to include nursing, dentistry, physiotherapy, nutrition, etc., etc., etc.. I expect the OP does want to become a doctor, though. --Tango (talk) 13:09, 23 April 2011 (UTC)

UHT milk in Greece

In Ultra-high-temperature processing, UHT milk's market share in Greece is only 0.9%.

The article says many northern European countries dislike UHT milk. I thought that Greece is in the south and it has very hot long summers. -- Toytoy (talk) 03:40, 23 April 2011 (UTC)

Do you have a question? That (poorly written and referenced) section also says "these figures conceal wide variations as in most European countries" whatever that means. If you can improve it please do so.--Shantavira|^{feed me} 11:07, 23 April 2011 (UTC)

ELECTRONICS

How can we find out any faults in super hectrodyne radio receiver?please explain with the circuit diagramMathematics2011 (talk) 04:03, 23 April 2011 (UTC)

top-antibottom mesons existance?

Do top-antibottom mesons exist, or does the short half-life of top/bottom quarks, and π⁺/D_s^{*+ mesons prevent them from forming? They are not listed on the list of mesons article. CS Miller (talk) 10:56, 23 April 2011 (UTC)}

Our article, top quark, says: "The Standard Model predicts its lifetime to be roughly 5×10⁻²⁵s. This is about 20 times shorter than the timescale for strong interactions, and therefore it does not form hadrons, giving physicists a unique opportunity to study a "bare" quark." So there aren't any hadrons, including mesons, that include top quarks. --Tango (talk) 13:42, 23 April 2011 (UTC)

Gold Vs. Silver

Gold, according to the article, is the most ductile and malleable metal.

Silver is not far behind though. I have a 99.9% gold necklace. Why is it so hard to find comparable purity in silver in jewelry? Most silver, when searched, is sterling silver (92.5% purity). It is said that silver is too soft so it must be alloyed with other metals, but this contradicts gold because gold is even softer; on top of this, but 24 karat gold is common.Curb Chain (talk) 11:31, 23 April 2011 (UTC)

24 Carat gold jewelry isn't that common either, especially in the West [13]. With both silver and gold, pure metal is typically only used when extreme malleability or softness is needed in crafting the part [14]. Where did you get your 24 carat gold necklace? Is it hand made, such that pure gold is necessary? Buddy431 (talk) 14:45, 23 April 2011 (UTC)

Young's double split experiment

Approximately how much time does it take for a "one photon at a time" YDSE to generate a distinguishable (by a computer) pattern, assuming that all photons pass through the slits and do not hit the barrier. Also, are there screen detectors that can detect a single photon and its approximate (x,y) coordinates? Or do we still use photographic plates or click detectors on tracks for YDSE's?

I've added a section header for you. --Tango (talk) 13:31, 23 April 2011 (UTC)

There is no number N such that you can distinguish the pattern using data from N subsequent photons but not from N-1 subsequent photons. The position where any given photon strikes is drawn statistically from a distribution. You may as well ask how often you have to toss a coin before you know P(heads)=1/2. The more data you have, the more certain you are that quantum mechanics predicts the correct position distribution for the photons (and the more coins you toss, the more certain you are that P(heads)=1/2), but in neither case is there a well-defined boundary between knowledge and ignorance of the pattern. 213.49.91.141 (talk) 17:35, 23 April 2011 (UTC)

The effects of dreams on long term memory

Recently, I was recalling something that happened years ago- a conversation with a friend- but, after further thought, I realize that it was actually a dream. I wonder how much of my memories are actually falsified by these "dream memories"? Obviously we remember nightmares or other implausible events that occur in dreams as dreams. But there is a lot of random normal stuff that happens in dreams that, over time, get mixed in with the memories of actual events. Anyway, is there an article about this? I also wonder if there are extreme conditions where a person's dreams and reality are totally indistinguishable...like a psychological condition? I looked at Dream#Other associated phenomena and Memory#Disorderes (as well as scanning the rest of the articles), and am not finding much along these lines. Quinn ^{✩ STARRY NIGHT} 13:37, 23 April 2011 (UTC)

Well our memories are notoriously poor anyway and our brain outright makes things up to fill in gaps (there a number of books on the issues that the fallibility of human memory creates - e.g. reliabilty in court) so I suspect it wouldn't be difficult for dreams to integrate into memories and become things you think happened. The article Interference theory may be of interest though doesn't specifically related to dreams. ny156uk (talk) 16:18, 23 April 2011 (UTC)

Speaker wire

I've read the wiki article on speaker wire and found the information I was interested in but wonder if something should be included about interference on speaker wire such as the 60Hz line voltage? If the power cord and speaker wire are close together is it possible the 60Hz humm may be audible through the speaker?50.46.189.84 (talk) 15:38, 23 April 2011 (UTC)

You're welcome to edit the article and include the relevant information yourself if you believe it belongs somewhere in there, but try to include a reliable source for it. Note that you can do this even without creating an account, just as you edited this page. Try to make sure it's an encyclopaedic piece of information though, not a 'how to' guide, i.e., a 'how to construct a speaker wire' section would not be appropriate as it's not the aim of an encyclopaedia article. --jjron (talk) 16:57, 23 April 2011 (UTC)

What is a Tripletino?

In the wikipedia article on Proton Decay it talks about a 5 dimension mode of proton decay with two fermions and two Sfermions. It also mentioned that this involves a tripletino of mass M. I am a little familiar with supersymmetry and this name fits the naming conventions of supersymmetry particles. However, I have never heard of such a supersymmetric particle. It maybe a generic name like neutralino that refers to any neutral supersymmetric boson. It is the "triple" that throws me. A triple of what? What are the properties of this hypothesized particle? I have only one reference in the whole world wide web. It comes from your article in wikipedia, but is cut and pasted all over the web with no further information.75.201.50.204 (talk) 16:34, 23 April 2011 (UTC)

Maybe its another word for a Neutralino? Just a guess... --Jayron32 17:08, 23 April 2011 (UTC)

Ocean surface lumps above sea mounts

A Natnl. Geo. documentary entitled "Drain the ocean" states that all ocean sea mounts are mirrored by lumps at the ocean surface level, and that the ratio is 1-1000. That is that a 3000 Ft. ocean sea mount is marked by a 3 Ft. lump of water above it. I've searched a number of Sea level cites and find a lot if info. about sea level variations caused by water temperature, atmospheric pressures, currents etc. but I can't find any explanation about how a sea mount deep below the ocean can cause a lump on the surface. It seems understandable that a deep current welling up the side of a mount might produce a lump but not all sea mounts are subjected to the same degree of current. How is this possible?190.149.154.38 (talk) 16:56, 23 April 2011 (UTC)

It's actually just gravity. The rock that makes up a sea mount actually attracts the water, 'bunching it up' and very slightly increasing the local sea level. (There's a more detailed explanation here.) Because of this distortion, sea mounts have been detected by precise satellite altimetry: [15]. TenOfAllTrades(talk) 17:13, 23 April 2011 (UTC)

The technical term is gravity anomaly, which refers to the "anomaly" in measured gravity between a perfectly spheroid (or perfect, complex-geometric-model-oid) earth, and the true gravity, which is affected by topography and geological composition and density. A fluid, such as the ocean, follows the contour of the gravity potential field; but because of surface winds, turbulence, tides, and other dynamic effects, true sea-level measurements are confounded by lots of practical details. In the open ocean, wind waves regularly have crest-to-trough amplitudes of 20 or 30 feet - so if there's a 3 foot "bulge", it's tough (but not impossible) to measure it!

Usually, if you want millimeter-accurate measurements of anything related to geodesy, you start with a reference geoid, such as WGS-84; apply your needed corrections using Shuttle RADAR Topography Mission data. That brings you to around a 2 meter accuracy. If you need more accuracy, you can correct these measurements using a local reference. If you were out in the open ocean, and you wanted to measure the sea depth with accuracy to ~ 1 or 2 feet, you could use a RADAR or SONAR measurement from a fixed object, such as a buoy or a semi-permanent man-made or natural structure on the seafloor, or an acoustic beacon.

Here's a chapter out of a textbook on geophysical estimation; this runs down the entire process of estimating sea-level bulges, with actual data from a satellite overflight of Madagascar. Altitude of Sea Surface near Madagascar; and further related work, Madagascar numerical estimation. Nimur (talk) 17:31, 23 April 2011 (UTC)

Many thanks guys. Even I can understand it. Why didn't I think of that. (Rhetorical). 190.56.18.215 (talk) 17:47, 23 April 2011 (UTC)