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Can this explain the double-slit experiment by a classical way?

  1. Aug 15, 2013 #1
    I found it very strange that matter behave as a wave and started thinking a lot...
    I have seen a video previously explaining this experiment and when I saw this:
    In red is the first path and in blue the second path.
    Could it be the answer?
    At the end of the video, in the screen of the experiment, we can see two big lines and at the edges lines that goes lighter just like experiments using electrons.
    Also the electrons are small, so if they collide with wall they would be a bigger pattern just like in the double-slit experiment.

    Thank you.
  2. jcsd
  3. Aug 15, 2013 #2


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    This is a common fallacy.

    Remember that in the double slit experiment, the initial condition is IDENTICAL all the time, i.e. you have a monoenergetic beam with a very specific momentum. That's the idealized starting condition.

    What this means classically is that all the "balls" can be aimed exactly at a particular location ALL THE TIME. I can hit that same slit and at the wall of the slit identically every single time! If that's the case, what do you think is the result after these balls passes through the slits? Do you think you'll get the same distribution?

    Secondly, and this is crucial to understand especially if you are not in science. You simply cannot make a handwaving argument such as this. There must be some quantitative estimation of the result, i.e. you need to use some sort of a classical distribution and make a quantitative prediction on how the result will look like. Physics isn't just saying "what goes up must come down". It must also say "when and where it comes down". So for your proposal to be taken seriously, it MUST have that quantitative calculation. And for this case, you need to show what your initial momentum/energy distribution of the balls are, and then calculate the trajectory of these balls if they hit either one single spot on the slit, of multiple spots on the slits, and then show the distribution pattern on the screen.

    Otherwise, it is a handwaving argument.

    BTW, you might want to also consider how you would apply your scenario when I show you a similar interference pattern made by superconducting current when they pass through two different circuit branches. It is the identical experiment to the double slit. Or, use the Michaelson-Morley interferrometer where instead of two slits, you instead have a beam splitter that separates the beam into two different paths. Where is the equivalent "bounce off the slit walls" in those two examples?

  4. Aug 15, 2013 #3


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    Also, if you actually simulate a "bouncing ball" system like this you will find that you will still not get anynthing similar to an interference pattern, unless you specify a VERY contrived initial distribution (not to mention the right width and thickness of the slits etc).

    So no, it does not work.

    A friend of my wrote a simulation like this as an excersise when we were undergraduates (I guess we must have been working on Monte Carlo techniques), I don't think it is available on the web anymore (this was 15 years ago); but there must be other applets out there that will do the same thing.
  5. Aug 15, 2013 #4
    It do when I made a 2 dimensional simulation.
    Also the wall is radiating electromagnetic radiation that we must include in account.
  6. Aug 15, 2013 #5


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    Then you are proposing your own new theory. If you think you are able to do that, then you've ignored the PF Rules that you had agreed to. Please re-read it.

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