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I Double slit experiment in 3 dimensions?

  1. Feb 14, 2017 #1
    Has anyone performed the double slit experiment in three dimensions? By this I mean, having double slits and a detection screen on three sides? This would imply there are 6 slits and 3 detection screens. What would we observe? Would we see the electron exhibiting wave like behavior (ie interference in 3 directions) and would the particle behavior at the detecting screen show interference patterns on all three detecting screens?
     
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  3. Feb 14, 2017 #2

    DrClaude

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    The way you describe it, this is simply three double-slit experiments running simultaneously in three different directions. I don't see why this would produce any unexpected result.

    By the way, there is no such thing as wave-like vs particle-like behavior. the concept of wave-particle duality has been abandoned long ago.
     
  4. Feb 14, 2017 #3
    Well, no I do not mean 3 double slit experiments running simultaneously. Only 1 electron is fired, not 3 electrons. There would be 3 double slits and 3 detection screens but only one electron gun. One double slit and detection screen would be in the conventional location. Another double slit and detection screen would be oriented to detect any transverse wave motion (say to the particles right) and another double slit and detection screen will be place to detect any transverse wave motion above or below the particles path.

    I think you can think of it as firing an electron into a cube. On 5 sides of the cube there are double slits and detection screens. The electron gun fires an electron in the direction of the 6th side which is open to allow the electron to pass into the cube.

    I do not think the concept of wave particle duality has been abandoned. If so can you please tell me what has replaced it? Are you saying that DeBroglie's equation has been discredited?
     
    Last edited: Feb 14, 2017
  5. Feb 14, 2017 #4

    ZapperZ

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    All this means is that you are using something that had gone through an interference and then having it pass through another slit. The orientation here is irrelevant.

    https://www.physicsforums.com/threads/double-slit-experiment-wave-collapse.902726/#post-5683981

    You misunderstood. Read one of your FAQ's here:

    https://www.physicsforums.com/threads/is-light-a-wave-or-a-particle.511178/

    Zz.
     
  6. Feb 14, 2017 #5
    No, I am not saying to place the double slits AFTER the electron has already passed through a set of slits. Think of firing an electron into box that is open on one side. All the other sides of the box have double slits and beyond each wall of the box is a detection screen. There would be 5 sets of double slits and 5 detection screens.

    I read the article you linked to. You are talking about light. I am talking about Debroglies equation, which embodies the concept of wave and particle. His equation implies that a wave has momentum. Has DeBroglies' equation found to be incorrect?

    And while I'm on it, what does it mean for a wave to have momentum?
     
  7. Feb 14, 2017 #6

    ZapperZ

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    But unless you are asserting that the electron goes through ALL of the different double slits ALL AT ONCE, then it will will go through one double slit and then the next, etc... So why is this not the same as what I had described? And why is your setup interesting or tells us anything new?

    I've done interference of electrons with not one, but MANY "slits". When I shoot low-energy electrons at a crystal surface, I get a 2D pattern of dots (LEED). I can send these electrons into as many other interference experiments as I want, in whatever direction that they go off. What will that tell me?

    Zz.
     
  8. Feb 14, 2017 #7
    It is not what you described. You implied that after the electron goes through one set of slits then then that interference wave passes through a successive slit. That is not what I am describing.

    Also, I am not asserting that the electron goes through all of the double slits at the same time but I think the Schrodinger Equation may create a wave function that tells us that is what may happen.

    Also I read the article you linked to. That is talking about light. I am not talking about light. I am talking about DeBroglies equation. DeBroglies equation assigns momentum to waves. What does it mean when one says that a wave has momentum? Has DeBroglie's equation been discredited?
     
  9. Feb 14, 2017 #8

    ZapperZ

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    Then maybe you should draw out your setup, and then explains what you are proposing. Otherwise, after rereading what you wrote earlier, I see no difference with what I described.

    Yeah? deBroglie proposed the existence of "matter waves". Both photons and electrons practically the identical properties. Look at, for example, single-photon interference versus single-electron interference patterns (G. Matteucci et al., Eur. J. Phys. v.34, p.511 (2013)). They are the same! As I've stated in the link to another post, it isn't the object, it is the SITUATION of the superposition of paths that is creating this effect. It is why photons, electrons, neutrons, protons, buckyball, etc... can show the same phenomena!

    Zz.
     
  10. Feb 14, 2017 #9
    I do not think it is that hard to understand what I am saying. It is actually a quite natural question to ask after one learns about the one dimensional version of the double slit experiment. Don't you want to know that the wave character looks like in 3 dimensions?

    You did not answer my question, what does it mean when we say that a wave has momentum?
     
  11. Feb 14, 2017 #10
    Quantum mechanics replaced it. There is no wave-particle duality in QM.
     
  12. Feb 14, 2017 #11

    ZapperZ

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    If you have taken basic QM classes, we solve the Schrodinger equation in 3D frequently (look at the hydrogen atom problem). So yes, I am quite aware of MANY situations that are in 3D.

    It means that it has the ability to "push" on something. What part of p=hk did you not understand?

    Zz.
     
  13. Feb 14, 2017 #12

    PeroK

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    If you are paddling in the sea near the shore, and a water wave hits you its momentum could knock you backwards. Why wouldn't a wave have momentum?
     
  14. Feb 14, 2017 #13

    DrChinese

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    :welcome:

    As you described your 5 sided contraption, there is nothing much of interest to talk about. There would be interference patterns at all slit pairs that are exposed to the source emitter.

    As to momentum: when particle momentum is well defined, position is not - and vice versa. Such a particle is not localized in the traditional sense. The trade-off between position and momentum definition is variable - it is not limited to all or nothing. What would you call something in between a wave and a particle? In quantum discussions, the term "particle" is usually used as the generic. Or you could also say electron or photon and be more specific. All particles have momentum, at all times, however it value need not be well defined at all times. Generally it will be conserved.
     
  15. Feb 14, 2017 #14
    And does that mean we will observe electron hits on all 5 detection screens? But we don't know that is what we will see. That is what we think we will observe. That is why we need to run the experiment.

    I know this but that is not a deep enough response for me. What does it mean for a wave to have momentum? Does it have any meaning at all?
     
  16. Feb 14, 2017 #15

    ZapperZ

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    Who is this "we" that you think should run your experiment? And do you think this is how one make a proposal to run such an experiment, when many of us here do not see the value of it?

    One of the things we all learn when we apply for a research grant is to show not only that something is interesting, but that it is also IMPORTANT. Those two are not always mutually inclusive. Based on your description, I see this satisfying neither criteria.

    But you know the "meaning" of a ball having a momentum?

    Zz.
     
  17. Feb 14, 2017 #16
    Quite frankly, I find your reaction to this a little harsh. For you to say you find nothing interesting in running an experiment like this I do not find credible. It is obviously of interest.

    Yes I do know the meaning of a ball having momentum. Momentum is a vector. How do I apply a vector to a wave?
     
  18. Feb 14, 2017 #17

    PeroK

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    One answer to your question lies in Special Relativity, and specifically the energy-momentum four-vector. In SR, the energy of a particle is the component of its momentum in the time dimension. This ties together energy and momentum, where classical physics does not. An electromagnetic wave also has both energy and momentum, as they are in fact different components of the same vector.

    A wave is clearly a vector as it has direction of motion, if nothing else.
     
  19. Feb 14, 2017 #18
    Whose interest, and whose opinion you find credible?
     
  20. Feb 14, 2017 #19

    DrChinese

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    1. It would be unreasonable for others to run experiments that have no theoretical point in question - just to satisfy your curiosity. You are of course welcome to run any experiment you like. You won't find much interest, however, for experiments that are completely in accord with theory and have little or no unique twist. Generally, scientists don't run experiments "just to see what happens". They have something specific in mind.


    2. Waves have momentum, which is defined as mass x velocity.

    https://en.wikipedia.org/wiki/Momentum

    To get a "deeper" response, you will need to do more self-study.

    NOTE: Rather than worry whether anyone is being harsh, you might pause to note that a number of experienced folks (including 2 mentors!) have taken time to help you.
     
  21. Feb 14, 2017 #20
    How do you calculate the total momentum for a wave? And if I did calculate the total momentum for the wave would I find that it was equal to the total momentum of the electron when it strikes the screen and all the mass is localized instead of spread out in a wave?

    And where is the center of mass for the wave?
     
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