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I Light has left me in the dark

  1. Mar 25, 2017 #1
    I was studying the double slit experiment and started wondering what exactly does happen to the wave when its in the slit that makes it diffract or not? I toyed around with http://www.falstad.com/ripple/ but could not figure what exactly goes on that makes things as they are.

    While trying to answer myself two additional questions came up:
    Does light require an EM field to travel through or does it create its own?
    Is light nothing more than a ripple through the EM field and if so how do we quantise it? Wouldnt it have a continuous nature (I know it doesnt) because of that?
  2. jcsd
  3. Mar 25, 2017 #2


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    I assume you mean what causes the interference pattern? It is not the slit per se. It is the effect from both slits.
  4. Mar 25, 2017 #3
    Well that would be something I dont know as well, but my question is what happens in a single slit when a wave passes through it? Why is it that when the wavelength is shorter than the slit a tight cone is observed on the other side and if its a longer wl it spreads out and we observe diffraction?
  5. Mar 25, 2017 #4


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    A light wave is an excitation of an EM field.

    You can think of (free) quantum field theory as a theory of an infinite number of particles.
  6. Mar 25, 2017 #5
    During my investigations I stumbled upon this description of the double-slit experiment. According to this description, interference is a natural by-product of the fact that the state of the photon in the double slit experiment is a superposition of two states. The part I find interesting is the description says the interference is caused by the relative phase difference caused by the differing distance the photon is from each of the slits. Here is the description.

    Last edited: Mar 25, 2017
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