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Photon in a shell

  1. Nov 3, 2004 #1


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    My Physics professor was teaching mordern physics yesterday and he gave us this experiment to ponder about

    Imagine we have a single photon in a spherical shell. The shell is 2 light years long. Now inside this big shell there is a smaller hemispherical shell with photon dectors at a distance of 1 light year away. Inside this sphere at the center is a photon. First I detect at the photon at the center of the sphere. By Quantum mechaincs (IS this true?) the probability of finding the electron elsewhere inside a region of the sphere increases. Now, we keep waiting and we dont observe anything. After one year, we still dont observe anything, but now we know that the probability of finding the photon in one half of the larger shell is much less. But we actually dont observe anything! How can this probability (If it is a quantum feature) change by mere knowldege?
    Last edited: Nov 3, 2004
  2. jcsd
  3. Nov 4, 2004 #2
    Can you explain what you mean with "the shell is 2 light years long"?
    Is it the radius?
  4. Nov 6, 2004 #3


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    yes, it is the radius
  5. Nov 8, 2004 #4
    Are we talking about wavefunction collapse here? I don't really understand your question, and can't really visualize the sphere (i suck at visualizing stuff, hence my geometry is sh*it). But if the last part of the question, the probability is not really changed, but there is no probability at all, once you actually "look" at the photon.
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