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Photons in vacuum functions

  1. Nov 2, 2006 #1
    I remember reading somewhere about vacuum functions; where a photon strikes a particle, which produces a chain reaction that results in the photon being shot back through time to start the reaction. (Or something like that)

    Now, since I've forgotten most of what I knew about this phenomenon, including what book I read it in, (and I read a lot of books, so it's no use going back to look for it) I was wondering if anybody here knew about such things. (Being able to describe the whole process at the particle level would be ideal.)

    As a side note, this is my first post here, so hello everybody!
  2. jcsd
  3. Nov 2, 2006 #2


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    When two photons of high energy collide, they create an electron and a positron. But a positron is just an electron travelling back in time. So by some piece of reasoning that I can't wrap my mind around at the moment, we conclude that it is possible that all the electrons in the universe are the same one.

    That idea (Wheeler's?) was explained to me by one of my professors a few years ago.

    This thread (https://www.physicsforums.com/archive/index.php/t-29040.html) in the PF archives says that Feynman's book QED as well as John Gribbin's In search of Schrodingers Cat talk about it.

    In that same thread, Robphy redirects the OP to this thread:

  4. Nov 3, 2006 #3
    I certainly like Wheeler's idea of a single electron zinging back and forth through time so many times that it makes up all the electrons in the universe.

    But how does that mesh with the experimental evidence that electrons can be created? They didn't pre-exist, so they have a terminus.

    So maybe some electrons are as Wheeler suggests, and others aren't.
  5. Nov 6, 2006 #4
    Ah, that's helpful! If nothing else, you've reminded me what book I read it in.
    Also, you've reminded me that I've had the wrong particle in mind; I should be focusing on positrons, not photons.
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