1. is it possible to entangle 3 instead of 2 particles?\n\ni would guess -- they cannot.
127899
Seems to me that if you can manipulate 2 particles into entanglement (let's say one in New York, one in LA), then you can also manipulate a third particle (in Chicago) to the qualities measured in the first.  Sorry mathematician, but your two/three particle wave function theory although fascinating doesn't apply
26055
No Way Man!  Photon-photon scattering?  Highly dubious.  Photons don't have charge. They don't self-interact, that's why the electro-weak theory works so well... right?\n\nResponse to Dr. Bob's response:\n\nI agree that this process occurs (although a photon that decays into a e+e- pair has to be close to another mass so momentum can be transfered; isolated photons cant decay into e+e-).  But in such a case, would you really say that "one light ray has bounced off another?" I'd say that it was "bouncing" off the electron/positron pairs.  Just semantics I suppose.
544786
Looks like only one person got the right idea so far so I will try to underscore that.\n\nEveryone who says that it is possible to have NOTHING inside a box if you have a total vacuum has ignored quantum theory which has proven to reflect reality extremely well.\n\nThe uncertainty principle allows energy to be borrowed from the vacuum for a very short time.  The vacuum is seething with pairs of "virtual" particle+antiparticle pairs that are created with this borrowed energy.  They pop into existence and then annihilate with each other extremely quickly.\n\nSo no, as far as anybody knows we have strong reason to believe that it is impossible to have absolutely nothing inside a box because something is always popping up everywhere in space.  Maybe if you had a very small box and very big luck luck it would be empty just for the tiniest period of time.
143894
They can't be explained. That's why the aforementioned string theory hasn't met a wide acceptance. There are other difficulties with string theory, but they would take a while to explain.
590106
None.  That is the point.  If they exist is not proved, and hypothetical tests to see if they exist are flawed.  \n\nOn your other question of visualizing multiple dimensions, I have a few hints.  Have you read Flatland yet?  Start there, its good, and not overly mathematical.  Multiple dimensions can mean different things to different scientists.  We use them all the time for their mathematical properties.  But mathematics is just a description, the real world is something observable.  In terms of observation, you would not be able to detect a separate dimension by any means pedantic.  We may be able to prove that physical space has more than three dimensions, but that does not mean that those other dimensions are physical space.  Just like time.  Some particle interactions appear to go backward in time briefly.  What if there is more than one time dimension?  \n\nSo the classic three dimensional physical picture of multiple dimensions will always be flawed by the observers expectation of the properties of the unseen dimension.  Which is why we describe those dimensions using 'imaginary' constructions.  Hope this helps a bit.
33959
Flipping over wouldn't be a problem; the asker is building a magnetic monopole on the ping-pong ball.  \nIs this possible?  Check the ref.website and find "Monopole Attempt".  They say that the other pole would leak out through the spaces between the magnets.  \nSomewhere I heard there's only room for one monopole in the universe.  \nWould the first person to do it be a monopolist?
427734
Not every problem should be solved with an elephant gun.\nJust ask yourself a different question. What is the probability that x2 is closer to x1 than to x3. since the answer to that question is the same as the question you ask and the only 2 possibilities are certain\nand mutually exclusive, the answer should be the same, 1/2.\n\nWhat about if x2 is exactly in the middle you ask?\n\nIt's like asking what is the probability that a random number in an interval is the midpoint. 1/infinity=0
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Sounds like you're asking about a quantum mechanical phenomenon sometimes called "spooky action at a distance."\n\nIn it's most basic form, it involves two "entangled" electrons (or any subatomic particle) If you could separate the pair by some great distance--even light years--and then influence some characteristic of one electron, its distant twin would react instantly to assume the same characteristic.\n\nTry this website for a more complete explanation -->http://www.everything2.com/index.pl?node_id=138524
584028
Yikes, I'll try, but it's tricky even for me!  And I've read a lot about it because it fascinates me!\n\nOK, the idea is that you have a cat in a box.  The cat is not visible to you, the experimenter.  In this box is a small amount of radioactive material and a geiger counter.  If one atom decays even the tiniest amount and the geiger counter catches this, a tiny flask of poison is broken and the cat is killed.  The "weird" part (hah) comes in here.  Whether or not the atom decays is strictly a probability issue.  However, using quantum mechanics, the cat would neither be alive nor dead until someone opened up the box to give it a "label" - to observe it and quantify it as alive or dead.  It would exist in a state of "alive/dead"ness, sort of.  \n\nSchrodinger used this as a way of pointing out that sometimes quantum mechanics just doesn't work for a given situation.
460423
Did you know that according to Quantum Mechanics, sub-atomic particles are capable of being in two places at the same time? Maybe if we shrink you down to that size, you will be, too.
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The first website gives a good overview with no math, if you already understand light/waves/atoms skip to the part that I put in paranthesis.\nThe third site is a more advanced and goes more into the consequences.  In case we have different ideas of what laymen are.\nHere's a quick summary:\nquantum entanglement is when one photon of light is split into two equal photons of opposite polarity (direction of the wave disturbance) .  The two photons seem to be linked in a way that is currently innexplicable but demonstratable using interference patterns.  Which I hope you don't consider techno babble, but if you do, just ask what interference patterns are and I'll answer that, too.  That's a quick expanations of what's happening.\nUnless you mean why, the last site does a pretty good job of explaining that we don't really know, but we're trying pretty hard to figure it out.  There are many theories right now.  It'll go over a couple of them.(it's really an excellent paper.  I don't know what level of physics education you have, but it was perfect for me.I'm not a physicist, I'm a chemist.)
609136
You want it literally untangled?  Here goes - it's a tricky one because you can't tell which negative pairs with which:\n\nAin't you going to not answer none of these questions no more?\nAin't you going to answer some of these questions no more?\nAre you going to answer some of these questions ...more?\nAre you going to keep answering these questions?  yes\n\ntry again\n\nAin't you going to not answer none of these questions no more?\nAre you going to answer none of these questions no more?\nAre you going to answer some of these questions ...more?\n\ncomes out the same!  whack. Once more for luck:\n\nAin't you going to not answer none of these questions no more?\nAre you going to not answer none of these questions...more?\n...same again!\n\nErgo, Dorypanda is logical despite her legendary forgetfulness and evolutionary stubbornness (bamboo shoots... I ask you...)\n\nYes, despite my best efforts, I am.
228411
This is an subject area where vocabulary is vital for clear understanding, to a degree I am not capable of, however the stuff that you ask about are so small that the only way to attempt to prove their existence is through mathematical formulae based on what we suspect to be true. Our lack of understanding on this subject, which is still very voung, means the answers available are sketchy at best compared to our understanding of molecular structure or atomic structure.\nWhat is known so far can be found in places like the noetic sciences knowledge centre, or wikipedia.
195510
I'm not sure I follow what you're trying to ask clearly enough, but maybe this will help.\n\nWhen A 'collapses' the wave function, he's affecting it, but not.  He gains the information about the entangled photons, but he hasn't actually changed the state of the photons.\n\nWhen B goes to 'look at' the entangled photons, he also sees the collapse.  However, wavefunctions only collapse because you see them as being in a defined state - it is impossible to look at something without it being collapsed.  B cannot observe photons in jar 1 to be non-collapsed.  By looking at it, it's collapsed.\n\nThere is debate whether these wavefunction collapses are due to our observations or simply a description of our lack of knowledge prior to observation.  Taking Schrodinger's cat... observing the cat does not change whether it is dead or alive, it merely collapses the 'wavefunction' of the cat's existance to being either alive or dead.
213973
This is the kind of question I like ... :-)\n\nNo, this is not information transfer. I will try to enlighten the problem by formulating it more precisely.\n\nBut first, I'd like to show that if you could tranfer information faster than light, you'd get a contradiction with special relativity.\n\nSuppose A can communicate some information faster than light to B. Let A sending the information be event 1, B receiving it event 2. If the message is travelling faster than light, it can be shown that in the reference frame of A, event 1 happens _before_ event 2, while in the reference frame of B event 1 happens _after_ event 2, which is a contradiction because Bob cannot receive the message before Alice sends it. If a light-signal cannot travel between events 1 and 2, we call them spacelike separated (at least in some other languages than English we do :-) ). Spacelike separated events don't have a definite temporal order (the order depends on the reference frame).\n\nOf course, in your example there is a correlation between the outcome of Alice's and Bob's measurement, but it cannot be considered information transfer. They always knew that they would get opposite results, but they didn't know who would get |up> and who would get |down>. Information transfer would mean that Alice already has a piece of data she knows, eg. a bit of 1, and she would like to transfer it to Bob. Bob's gaining knowledge of this information is the result of Alice's sending it. So there is a definite temporal order (and causal relationship) between these events. In the entagled particle-pair example she doesn't have this piece of information before she does a measurement.\n\nHowever, you could say that A can transfer information like this: she does a measurement, and as the result of the measurement the wave function of both particles collapses, and B can measure to see if his particle is in a collapsed (|up> OR |down>) or superposed (|up> + phase_factor*|down>) state. So B will know if A has already measured or not! But B cannot decide which state the particle was in with only one measurement! And he can make only ONE measurement, because the measurement collapses the state. As a result he will always get either UP or DOWN, so he cannot tell if the original state was |up>+|down> or one of |up> or |down>.\n\nOf course if B could copy the state of his particle, he would be able to make multiple measurement on the same quantum-spin-state, but he cannot copy the state because of the no-cloning theorem (Zurek-Wootters, Nature, 1983 if I remember well, but anyway, see it on Wikipedia). Of course, if he would be able to copy the state, we would get a contradiction with special relativity.\n\nAs satanorsanta pointed out there are still problems with the _interpretation_ of quantum mechanics (especially with the measurement postulate), but I wouldn't consider this specific question unsolved.\n\nI know my English is not the best ... I hope you will understand my reasoning. If you's like to chat about these thing, send me a mail.
198708
I would say NO... at certain point, particles are made of energy, and energy can't be splitted as matter does...
655904
Well this one is interesting.  Mathematics tell us that to move in time, one must move faster than the speed of light.  There are particles that do move that fast so it is theoretically possible.\n\nWith that having been said, I'll go back to the particles that move faster than light.  These particles cannot be seen or measured in any way that we can figure out but we know that they exist because of the reaction of other things.  ( its like the wind blowing,  you dont see it but trees and stuff react to it )\n\nOne theory suggests that if we do manage to travel back in time,  we wont be able to interact with it at all. ( I dont understand all the mechanics on this one)  But it would be like being an invisible ghost.  You could observe things and events but couldnt make actual physical contact with anything thus you couldnt change events.