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Thoughts on double slit

  1. Jul 10, 2004 #1


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    I suppose someone has thought of this but is the supposed "interference" of light particles in the double slit experiment actually only the apparent interference of light particles and actually an interference of paths open for the light particles to travel? I. e. it is something else creating the interference and the light merely travels along the paths open to it, the paths of least resistance, in an interfering medium or field?
  2. jcsd
  3. Jul 10, 2004 #2


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    Also, has the double slit experiment ever been done in a vacuum?
  4. Jul 10, 2004 #3
    intresting observation but these interference patterns also occur for electrons .
    richard feynemann says that all patricles follow every possible path. He calls this the sum over histories.
    P.S you would get the same result in a vacuum
  5. Jul 10, 2004 #4


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    As to the results in a vacuum, has it been tested?
  6. Jul 11, 2004 #5
    Electron diffraction

    LEED (Low energy electron diffraction) and RHEED (Reflection High Energy Electron Diffraction) are two experimental setup commonly used in material (surface) science.

    Both experiments result in diffraction patterns, where the wave-like nature of electrons is used to determine the crystal structure of material (surfaces).

    So we can say that electron diffraction (as well as light diffraction...) occurs also in vacuum.

    Hope this answers your question.
  7. Jul 11, 2004 #6
    Yes but Feynman still theory not established knowledge.

    The two-slitter has been done numerous times with electrons,photons and buckyballs ( buckminstertoluene ), which are roughly the diameter of their wavelength.
    It seems that anything bigger ( in physical reality ) than it's wavelengh can not interfere with itself.
    As for vacuum, yes, electrons in cathode ray tube one at a time built up interference pattern, so a single particle can seem to interfere with itself
    Last edited: Jul 11, 2004
  8. Jul 13, 2004 #7
    the two slitter is annoying... maybe the particles leave traces in the material in which they propagate... maybe they exist outside from the time dependent state or dimension... maybe nobody have studied the slits long enough to figure out if their physical properties have anything to do with it...
    too much for ten physicists to find out in one lifetime, i'll bet...
  9. Jul 14, 2004 #8
    IMHO we wont get a grip on the double slit experiment before we understand the wave function (wf) itself :frown: . When the wf is not collapsed what value(s) does it have? Superposition says theory, but that implies a split :grumpy: of the particle itself. Is the universe really schizofrenic? :rofl:
  10. Jul 14, 2004 #9

    mee,you may go to lectures on physics vol 1 by prof. feynmann.also u can go through that by hecht.actually there is nothing called "something else" in physics.just thing as energy quanta & u ll get it. :smile:
  11. Jul 14, 2004 #10


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    why rudra

    Just because "something else" hasn't been thought of doesn't mean it doesn't exist. To say that we have discovered all there is to discover in physics seems arrogant. We don't even know what dark matter or dark energy is though it may exist all around us.
  12. Jul 15, 2004 #11
    You are right when you say
    >>To say that we have discovered all there is to discover in physics seems arrogant.
    However, the double slit experiment is really puzzling, and people have been thinking about very hard for a while now. (This is for balkan : I bet you have not read Feynman.) Your "something else" is not only unnecessary. Any attempt in order to build a classical-concept reinterpretation of the double slit experiment leads to unconsistencies, as far as I know. As Feynman explains it brillantly, there is no way out of this : if you do not detect by which slit the particle goes through, then it is going to interfere, i.e. it is going through BOTH slits.

    THE ELECTRON IS GOING THROUGH BOTH SLITS if you don't detect it. If you detect it, it is NOT interfering anymore.

    Even if you try to reduce the perturbation induced by the detection, the interferences are restored at best when the indeterminacy in position becomes of order of the slits separation. You see there is no way out. Nature is perfectly clear to us about that.

    I must add to this that nobody understand deeply what's going on here. The double slit experiment might be the first and most important experiment to motivate quantum theory, yet it remains one of the most disturbing fact of elementary quantum mechanics.
  13. Jul 15, 2004 #12
    The word detect is misleading , the apparatus already 'detected ' the electron what happens is that when you introduce another observer you have changed the apparatus and the results reflect that, otherwise people seem to assume it's a human observer which is key to the experiment -- it's not.
  14. Jul 15, 2004 #13
    Bohmian mechanics shows that it is possible to have a consistent interpretation of the double slit experiment with the particle only ever going through one or the other slits, irrespective of whether there are detectors behind the slits or not. Sure, it is a rather weird theory in many respects, but it shows that such interpretations do not necessarily lead to inconsistency.
  15. Jul 15, 2004 #14
    to slyboy , seems incorrect when you measure 'detect' at one slit you find the photon /electron and no inconsistency is present , but that of course changes the apparatus.
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