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Hawking Raditation and particle-antiparticle pairs

  1. Dec 2, 2008 #1
    The way I understand it it, black holes decay because particle-antiparticle pairs appear so close to the black hole that the particle gets away, but the antiparticle falls in and annihilates part of the black hole (Hawking Radiation), but there are two things I don't understand:
    1) When the antiparticle falls in, doesn't it add energy to the black hole (because energy is always positive) and shouldn't it increase the size?
    2) Why would more antiparticles fall in than regular particles, since the eruption of pairs from the vacuum is random, shouldn't equal numbers of both fall in while equal numbers of particles and antiparticles escape as radiation? Wouldn't this mean that the black hole's size shouldn't change (or if my understanding of 1 was right, get bigger).
    Any insight would be appreciated.
  2. jcsd
  3. Dec 2, 2008 #2


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  4. Dec 3, 2008 #3

    George Jones

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    Read the stuff at the link that cristo gave.

    Particles and anti-particles are equally likely to fall into the black hole, and, yes, both real particles and anti-particle have positive mass/energy. Virtual particles and anti-particles can be off-shell, and even can have negative energy, If a negative energy particle or anti-particle falls into the black hole, the mas of the black hole decreases.
  5. Dec 3, 2008 #4
    @cristo: Nice link!
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