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The Airy disk/Slit Experiment

  1. Dec 16, 2003 #1
    I wanted to know if my understanding of wave-particle duality fits in with Bell's Theorem or any other for that matter.

    The way I see it is that particles exist in multiple dimensions simultaneously. One of these dimensions is the medium in which it is traveling or moving in ie the wave properties, or in the case of chemical reactions the space in which it is reacting eg a beaker. The other dimension would be time another still would be the dimension of observation. So a particle being fired through an aperture or slit 'sees' the other particles and where they have landed as it exists outside of time and sees all time frames of the dimension in which it is in ie the dimension of observation.

    So to simplify what I'm saying is a particle is aware of it's wave properties, it's partner particles and the aperture/slit within the dimension of observation. So whether a particle is fired one at a time is irrelevant, as the particle is already aware of it's observed dimension and what it is interacting with, and what is interacting with it, ie the observer, other fired particles and their collective wave pattern. I propose that it is the act of observation which causes it's final collapse or determines its locality.

    Silvershadow
     
  2. jcsd
  3. Dec 23, 2003 #2
    Silvershadow,

    Let me ask you this question too. This might be a very stupid question, but I’ve never understood mystery of the double slit phenomenon. In this demonstration, why wouldn’t the dot of laser light hit the card the slits are on, right in the middle between the slits, and thus not go through either slit?

    LINK TO JAVA DEMO
     
  4. Dec 24, 2003 #3
    Re: Re: The Airy disk/Slit Experiment


    You would simply use slits that were closer together if this were the case.
    The demo is a graphical representation allowing us to see what affect slit seperation has. In reality they are very close together.
     
    Last edited: Dec 24, 2003
  5. Dec 24, 2003 #4
    Re: Re: Re: The Airy disk/Slit Experiment


    Thanks.

    This type of demo and illustration irritates the heck out of me. For years I’ve looked at illustrations like this in books, and I’ve seen drawings of giant slits far apart, and I’ve wondered why the dot from the laser just didn’t hit the slit card in the middle between the slits.

    A better illustration would just show two side by side lines like this || and say they are two slits very close together so that the laser dot, which has a small diameter no matter how small it is, goes through both slits at the same time.
     
  6. Dec 24, 2003 #5
    Re: Re: Re: The Airy disk/Slit Experiment

    Ok, so in the question about whether an electron is a particle or a wave, could it be that when a single electron is sent to the dead center of the space between the two slits, that could slice a particle-electron in half, causing one half of it to go through one slit and the other half to go through the other slit?
     
  7. Dec 24, 2003 #6
    Re: Re: Re: Re: The Airy disk/Slit Experiment

    There are different interpretations of this experiment, but simply put, the 'electron' doesn't go through either. An electron behaves like a wave and the wave goes through both slits at once creating a wavelike interference pattern. (I am sinplifying this a great deal)
    If you sent one electron through at a time (or one neutron, photon etc) and recorded on a screen where it ended up, after hundred and thousands of events, you would have built up a perfect interference pattern.
    So, the electron can be thought of as going through both slits at the same time and interfering with itself. Alternatively, you could just think about it as a wave with a corresponding wave function.
    Some prefer the 'many universe' idea where the electron goes through one slit in one Universe, and the other slit in another one.

    We can only really calculate probabilities and explain the result. Visualising 'what actually happens' is not possible.
     
  8. Dec 24, 2003 #7
    Re: Re: Re: Re: Re: The Airy disk/Slit Experiment

    Thanks!
     
  9. Dec 25, 2003 #8
    could it be that when a single electron is sent to the dead center of the space between the two slits, that could slice a particle-electron in half, causing one half of it to go through one slit and the other half to go through the other slit?

    If the experiment is properly conducted it should preclude the possibility of the delocaliztion of the electron or to assume that it is “spread out “ in space partially passing through one slit and partially through the other. This has been established experimentally.
    The Double Slit experiment is generally considered to be one of the decisive experiments on which quantum theory is based. However from reading this post and others it becomes clear that there are considerable fallacies associated with the interpretation of this experiment:
    1) It is first established that with only one slit open , no interference is seen. Thus the interference pattern does not arise as the result of the slit being too small to accommodate the particle / wave.
    2) The electron or particle being used does not pass simultaneously through both slits , it either passes through one slit or through the other but never through both simultaneously.

    Having established these ground rules , it is possible to continue to the implications of the experiment. When single electrons pass through a single slit what is perceived is that the electrons ( when calculated over a number of trials ) all land within the classical expectations of where they should be expected to arrive. However if both the slits are open and a single electron passes through one of the slits , the probability ( over a large number of trials ) is that it will land in the area created by the interference pattern created by light (or the particles in question ) passing simultaneously through both slits . The crux of the question is how does the particle sense (or perceive ) that the other slit is open ? According to classical theory ( if the aether theory is ignored ) there is no way that such a phenomenon can take place. Yet , even quantum theory with its stipulation of all pervasive electromagnetic waves , believes to a certain extent in a sort of aether theory which if applied to this particular experiment , would undermine everything that quantum mechanics says about the experiment. So the question is , what exactly does the experiment prove or disprove ??
     
  10. Dec 25, 2003 #9
    When I first read about the double slit experiment, maybe 20-30 years ago, I read in a couple of places the slits could be a couple of mm wide and several mm apart. So a “beam” dot that is smaller than the width of the distance apart of the two slits, will just hit the center of the card in between the two slits.

    I had a friend who got a diffraction banding effect on some film with just one slit about 3 mm wide.

    I’m not sure I believe that just one “photon” and just one “electron” has ever been fired at two slits as individual units. Do you have any sources for the original “one photon” and “one electron” experiments? Are these “thought” experiments or real experiments? I’ve noticed over the years that the number of myths floating around in the world of theoretical physics “thought experiments” is enormous.
     
  11. Dec 26, 2003 #10
    David,

    I’m not sure I believe that just one “photon” and just one “electron” has ever been fired at two slits as individual units. Do you have any sources for the original “one photon” and “one electron” experiments? Are these “thought” experiments or real experiments? I’ve noticed over the years that the number of myths floating around in the world of theoretical physics “thought experiments” is enormous.

    You've brought up a good point. Of all the the electon 2-slit diffraction experiments I've read about, they get into the "1 electron at a time through the apparatus" by counting the number of detections and computing that on average there is only 1 electron transvering the experiment at 1 given instant.
     
  12. Dec 26, 2003 #11
    Thanks for the info!
     
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