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Antimatter colliding with matter

  1. Mar 19, 2013 #1


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    I read somewhere that if a particle of antimatter collides with a particle of matter, they annihilate each other.

    Maybe this is because of what is happening in the 4th dimension(time). Since antimatter is matter traveling backwards in time, maybe the two particles stop in the 4th dimension when they collide, causing them to stand still in time, giving the illusion that they disappear...
  2. jcsd
  3. Mar 19, 2013 #2

    Simon Bridge

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    Welcome to PF;
    When matter and antimatter annihilate, they do not just vanish. Their energy continues as a photon.
    It is usually a good idea to find out what others have done in a field before proposing personal theories.
  4. Mar 20, 2013 #3
    2 photons??
  5. Mar 20, 2013 #4
    In the case of positron -electron annihilation yes two photons.
  6. Mar 20, 2013 #5


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    "Stopping in time" doesn't mean to disappear. They are converted to photons which do not experience proper time (do not age)
  7. Mar 21, 2013 #6

    Simon Bridge

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    Single-photon annihilation of a positron is possible in the presence of a high Z nucleus.
    Sodickson, L.; W. Bowman, J. Stephenson (1961). "Single-Quantum Annihilation of Positrons". Phys. Rev. 124, 1851–1861 (1961).

    The "agelessness" of photons is a frequent topic in these forums - i.e.
    Do Photons Age
    ...'age' is sort of a meaningless concept for a photon. If you mean does time pass for a photon, the answer is that photons travel along paths of zero proper time in spacetime, so the answer is no. On the other hand, if you mean if we could somehow watch a photon travelling (from a frame that *wasn't* travelling at the speed of light) would time pass for *us* whilst we watch the photon, the answer is obviously yes. So we could arbitrarily assign an 'age' to the photon from our frame, say, it's time begins when it is emitted from the atom, and ends when it is absorbed by one. The problems are firstly that the age would be frame dependent (this is the whole idea behind proper time in the first place) and secondly we can't actually 'see' or observe a photon until it's been absorbed - it's path before measurement has no real meaning as far as we can make predictions about it. Therefore there is no process by which a photon could even be *given* an age, as far as I am aware. Meaningless concept.
    -- Kane O'Donnell
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