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Electron annihilation - what happens to gravity

  1. Jun 15, 2012 #1
    It is my understanding (?) that, when an electron is annihilated, the resulting photons do not react with gravity. Why isn't that quality conserved?
  2. jcsd
  3. Jun 15, 2012 #2

    Vanadium 50

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    Your understanding is incorrect. Where did you read that?
  4. Jun 15, 2012 #3


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    Gravitation acts on energy. An electron+positron-annihilation produces photons, which have energy, too.
  5. Jun 15, 2012 #4
    I must be misinterpretating the thing about photons not having mass - that electrons interact with gravitons but photons do not.
  6. Jun 16, 2012 #5


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    As mfb said, "gravitation acts on energy". The fact that photons have 0 mass does NOT mean they are not affected by gravity.
  7. Jun 16, 2012 #6
    The title of the thread stands as an interesting question.

    A particle-antiparticle pair is hald apart by a magic thread. The system has an almost exactly spherical gravitational field.

    At the moment of anhiliation, a pair of photons fly away is opposite directions to preserve momentum, spin, charge and everything else.

    A gravity wave should expand spherically outward from the moment of anhilation to terminate the gravitation from the defunct particles.

    Does this wave contain the binding energy of the particle pair or is it a fraction of their rest masses? Or does it coincide with and somehow represent the outgoing electromagnetic front which is also spherical (even though the two photons will eventually be detected in some colinear trajectory.)

    I think I know the answer but I'd like an expert opinion.
  8. Jun 17, 2012 #7
    Is there a quadrupole moment in this case?
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