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I problem I am struggling: Experiment included.

  1. Aug 30, 2012 #1

    First I would like to say I don't have a formal education in physics but I've dropped everything in order to pursue an education in it. My knowledge is at least high school level and dipping into higher level.

    Recently I thought of a situation and devised an experiment around it. It was based on a problem, I have attached a .jpeg illustrating the experiment and its premise. Even then I will describe it here, along the reasoning I used. It was inspired by the double slit experiment and the phenomena correlated with it. My greatest interest was in the the actual interference. So I pondered:

    What if you could create two beams, which are ideally identical in every way (frequency, wavelength, synchronization) and all components are ideal, and they both meet (illustrated in attachment) out of phase and as such "negate" each other, i.e the sum of the E and M fields are 0?

    When I mean ideal I mean ideal; complete vacuum, etc,. I realize that actually building such an experiment physically might be practically impossible, really this is an issue about the theoretical aspect.

    I have asked this question to a professor and several grad students and I have only received an, "I don't know.".

    Attached Files:

  2. jcsd
  3. Aug 30, 2012 #2
    Once the antiphase photon gets into an emitter, what happens there? There are not too many options. All of them imply that the emitter will have to emit the absorbed energy in some way.
  4. Aug 30, 2012 #3


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    Reflection necessarily introduces a phase shift. This is not just some practical issue, but a very fundamental limitation. Any beam splitter, merger or divider, whether in the visible or radio frequency or whatever range, cannot leave the relative phase of transmission versus reflection unchanged. As a consequence, if you get destructive interference at one exit port of the beam splitter, you necessarily get constructive interference at the other port.

    As a fundamental rule you cannot ever dynamically create a situation where destructive interference occurs without having constructive interference occurring somewhere else.
  5. Aug 30, 2012 #4
    Thanks for the answer. I suspected that there was something fundamentally wrong my question, though, I can't lie, a small part of me felt "smart" when a prof didn't manage to answer it. Worst part is I read about it this in my textbook and already forgot. I have a follow-up question, but I'm so tired at the moment I can't remember it (just noticed the broken English of the title).
  6. Aug 30, 2012 #5
    Just because the prof had no answer doesn't automatically make you profound. There is a vast asymmetry between posing questions (easy) and responding with a correct, succinct answer (lots harder). That's the story of science, where we work on questions that might have been posed decades or centuries ago. An equally tough task is often that of formulating the question correctly in the first place. Without that, a meaningful answer might not be possible.
    Last edited: Aug 30, 2012
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