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Hawking Radiation

  1. Dec 8, 2014 #1
    Something I don't understand is how the energy is subtracted from the black hole. So lets say one pair of virtual particles pop up on the event horizon, the particle goes in, the antiparticle goes out. Then lets say that a second pair does the opposite.

    My first question is why is the antiparticle from the first pair colliding with the particle from the second pair any different than colliding with its original partner? Has it just had enough time to become a real particle and therefore emits a photon to conserve energy?

    If so, wouldn't the two particles colliding inside the event horizon give off light as well? How is the energy removed from the black hole?
  2. jcsd
  3. Dec 8, 2014 #2


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    I find this very weird myself. The standard "explanation" I have heard several times on this forum is that it doesn't matter which particle falls in, it automatically has negative energy and thus reduces the mass of the black hole.

    More significantly, the whole issue of "virtual particles" as the mechanism for Hawking Radiation is bogus. Hawking said that this "particle pair" thing is JUST an analogy that was the closest he could come to describing in English something that really can only be described in the math.

    As to another part of your post, anything that happens inside the event horizon is irrelevant to the rest of the universe and does not cause any loss of mass to the black hole.
  4. Dec 10, 2014 #3
    But what is the physical process. What does a particle with negative energy actually do to the black hole (other than just saying it takes away energy)?
  5. Dec 10, 2014 #4


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    Taking away energy is equivalent to taking away mass and that is what Hawking Radiation IS ... the removal of mass from a BH.

    EDIT: I think I stated that a bit awkwardly. Taking away mass from a BH is the EFFECT of HR, not quite "what it is" as I said originally).
    Last edited: Dec 10, 2014
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