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Isn't all action, spooky action at a distance

  1. Jul 23, 2012 #1
    There is a lot of empty space inside a proton. A proton is 10^-15 m and a quark is 10^-18 m, so that's 3 orders of magnitude which is equivalent to 1 m versus 1,000 meters. And there is certainly even more empty space inside a quark but we don't know for sure yet if ever. So two protons do not occupy the same space due to the Pauli Exclusion Principle, therefore 3 quarks, say 1 meter long, do not occupy the same space as three other quarks a 1000 meters away because of some mysterious property they have. They are acting at a distance. They know that they are not supposed to occupy the same space that three other quarks occupy and they are doing this at a distance. Is this picture correct?
     
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  3. Jul 24, 2012 #2
    there are nuclear forces involved in case of protons, neutrons etc..i think

    in quantum entanglement scientists have been unable to detected the "forces/fields" (if they do even exist) yet.

    also- the disturbance travels (max) at the speed of light in case of the four (yet known) fundamental forces. however in case of quantum entanglement it's thought to be instantaneous or at the least/minimum 10,000 times the speed of light
     
    Last edited: Jul 24, 2012
  4. Jul 24, 2012 #3
    I'm talking about how the protons know not to occupy the same state of another proton.
     
  5. Jul 24, 2012 #4

    DrChinese

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    There is a lot to comment upon in your description. First, protons repel because they are positively charged, not because of the Pauli exclusion principle. This repulsion is more than overcome by the attractive effect of the strong force.

    Second, action at a distance between the nucleus and its bound electrons occurs by mediation of the electromagnetic force operating at the speed of light. There is nothing "spooky" about that (in normal parlance), what is considered spooky is when the effect is instantaneous.

    I would recommend that you read up a bit more on the Standard Model, there is a lot to understand in the structure of an atom.
     
  6. Jul 24, 2012 #5
    You still have the problem of how the proton knows that another proton is a proton and not a neutron. Two, how is that protons do not occupy the same space as a neutron?
     
  7. Jul 24, 2012 #6

    DrChinese

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    The structure of the nucleus is mostly described as a result of the strong nuclear force. Therefore, both neutrons and protons are "attracted" into the bundle we call the nucleus (only protons repel electromagnetically), and both are spin 1/2 particles. The interactions between these particles are mediated by forces which operate at the speed of light c. By definition, these are not spooky.
     
  8. Jul 24, 2012 #7
    You don't understand what I mean. Let's focus on the Pauli Exclusion Principle. When one billiard ball hits another billiard ball, the quarks from one billiard ball do not touch the quarks from another billiard ball. The quarks from one are pushing the quarks from the other but they do it at a distance, they never touch each other, even though that distance is 10^-15 m it is still a distance. The 3 quarks are only 10^-18 m yet a 4th quarks cannot enter into a space 10^-15 m, that's equivalent to three one meter objects occupying a space 1000 m's large and excluding anything from entering into that space.
     
  9. Jul 24, 2012 #8
    Speaking in layman terms, the particles keep a distance between them because they don't interact directly but via other particles called gauge bosons. In the case of quarks, these could in principle be the gluons of the strong interaction, but they only act on very small distances. In your case, it will be the photons of the electromagnetic interaction which mediate the repulsion between the billard balls.
     
  10. Jul 24, 2012 #9

    DrChinese

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    Not sure about your question then, as it seems you have a suitable understanding of the nucleus. There is of course a field effect, a sea of virtual particles, etc. The PEP is relatively short range, obviously affecting electrons over a larger distance than nucleons. So the question seems to be, how does any quantum system know to behave according to these rules? Or are you saying that the PEP acts non-locally? Or?
     
  11. Jul 24, 2012 #10

    Bill_K

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    g.lemaitre, You're making a common mistake of thinking that quantum particles are somehow just like classical particles, only with the Pauli excusion principle tacked on. In the classical world, if you have two marbles, say, you have two things. And they only find out about each other by direct contact. In the quantum world, if you have two identical fermions, you have one thing.

    They are excitations of one and the same quantum field, whether they are 10-13 cm apart or 10+13 cm apart. And it is simply impossible for both of them to be in the same state. The Pauli principle does not just forbid them to be located at the same point, it says the two-particle wavefunction that describes them must be antisymmetric. This is not a 'force' or a 'repulsion' or 'action at a distance'. It's a basic property of the field, and you can't create an excitation (i.e. a particle) that violates it.
     
  12. Jul 24, 2012 #11

    DrChinese

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    As I understand his question, I think you are answering it. That would make the system exhibit the non-local property that would provide the spooky action at a distance. I guess I hadn't realized this element existed in the puzzle as you would need to bring the particles together first (I guess).
     
  13. Jul 24, 2012 #12
    Ok, I decided to track down a passage form Paul Davies that sort of addresses my problem. First I'm not claiming that there is action out there faster than the speed of light except of course entangled particles, the passage by Davies below does point out a conundrum.

    What I'm concerned about is how one object communicates its presence to another object. So a billiard ball pushes another one due to electric charge because all the protons of the ball are surrounded by electrons and electrons repel each other. But I didn't know that this repulsion was communicated by photons or is it? Would someone walk me through just exactly what happens when a ball collides with another and how this collision is communicated at the electron level.

     
  14. Jul 25, 2012 #13

    Bill_K

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    There really isn't that much to it.

    Atoms like to be a minimum distance apart. If you try to push them closer together, they push back! The simplest example to talk about is two hydrogen atoms. Approaching each other, they can bounce apart, or they can form a hydrogen molecule. How close they come results from a quantum mechanical calculation, in which you look for the minimum energy configuration. In doing this, you have to take into account the repulsion of the two electrons, the repulsion of the two protons, and the attraction of each proton for each electron. And -- the Pauli exclusion principle.

    But the force between atoms is basically electrostatic in origin. This force comes into effect when you collide objects, and also produces the elastic restoring forces when you squeeze an object.
     
  15. Jul 25, 2012 #14
    I know all that. I'm trying to get beyond that simple picture. Is repulsion communicated by photons? The fact that one electron knows that another is repulsive, is there an explanation for that, or is it just a brute fact? If two electrons do not exchange messenger particles, photons I guess, then it would appear that they are aware of each other instantaneously.
     
  16. Jul 26, 2012 #15

    DrChinese

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    This is a field effect (virtual particles are involved). Photons mediate the force between charged particles. And that is NOT instantaneous. How repulsion and attraction itself actually occurs is a more complicated process and probably beyond the scope of this thread. Suffice it to say that whenever you have mediation by particles like photons (electromagnetic force) or gluons (strong force), the effect propagates at c and no faster.
     
  17. Jul 26, 2012 #16
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