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I question the double-slit experiment:

  1. Feb 27, 2013 #1
    Concerning the double-slit experiment:

    In the basic version of this experiment, photons pass through a thin plate pierced by two parallel slits. The photons (interference pattern) are observed on a screen behind the pierced thin plate.

    If you change the depth of the slits does it change the diffraction pattern?

    I question if the thin plate material causes the interference pattern?

    I question if the thin plate material black body absorption radiation and temperature causes the light wave interference pattern?

    If you change the temperature of the thin plate to near absolute zero will this change the diffraction pattern?

    Thank You,
  2. jcsd
  3. Feb 27, 2013 #2


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    Not in any relevant amount.
    No. If the material would emit so much light, you would see it glowing. In addition, this light would be radiated in all directions.
  4. Feb 28, 2013 #3
    You're confused about Black body radiation and quantum excitation

    Quantum excitation is something that happens when a photon interacts with an electron of a FREE atom. Electrons act very differently when they're in some sort of rigid structure like a pure metal or (even worse) something more complex like glass or plastic. If you want to know how exactly electrons in a pure metal behave when interacting with light there is a very famous phenomenon called the photoelectric effect.

    If you look at that you'll see that "re-emission" of light is impossible. The light will either eject electrons from the solid or it won't. Either way this causes a slight increase in the solid's temperature.

    Now that's a SLIGHT increase. Nowhere near enough to make it hot enough to emit visible light as black body radiation. If the light source was powerful enough to actually make it that hot then the material would likely melt. And as said before it would radiate in all directions like a light bulb.

    Luminescence is not a type of black body radiation, and it requires some sort of process involving a large release of stored energy. A light source certainly could not be the only fuel for any reaction whose product was the exact same wavelength of light, as you seem to be suggesting.

    But most importantly. The diffraction of a light is a well-established theory which makes a lot of very good predictions and you haven't given any reason to suggest that its wrong. If you had evidence that the depth of the slits or the temperature of the material makes some significant difference then you'd have a reason to try to find some alternate explanation for diffraction patterns. In any case it would have to be very different from the explanation you have now.
  5. Feb 28, 2013 #4


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    Welcome to PhysicsForums, Symmetry3!

    As already mentioned, your ideas about the source of the interference are not applicable. The following may help you to see this.

    If you place polarizers in front of each slit, aligned parallel, you get interference. If you change the polarizers so they are perpendicular, the interference disappears. This is because it is possible, in principle, to determine which slit information in this instance. So clearly, the variables you describe do not contribute to the result in any meaningful manner.
  6. Feb 28, 2013 #5


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    Furthermore, the double slit isn't unique to just this type of setup. We have seen such similar interference in everything from electrons, neutrons, and even buckyballs! It implies that this is a more general principle, rather than tied to a specific setup and "thickness of slits".

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