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Blackhole Radiation

  1. Feb 9, 2005 #1
    OK guys I know that one of the ways that blackhole radiation is detected is by detecting some sort of radiation.

    My question is.... is this radiation or whatever released at a point were light cannot escape from the blackhole? I mean the escape velocity from blackholes is immensly greater than even the speed of light so how exactly does the radiation or whatnot escape the gravitational feild? Or does it happen before an object crosses the event horizon? I am curious exactly how this works. Thanks :smile:
  2. jcsd
  3. Feb 9, 2005 #2
    If I am not wrong, what I have learnt is that it has something to do with thermodynamics of the blackhole system. There is existance of virtual particles in empty space, and one type is beyond the event horizon and its anti-particles is outside the event horizon. In effect, you will see a net dissipation of particle radiation from the black hole, which in effect is its blackhole radiation.
  4. Feb 9, 2005 #3


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    Hawking radiation, as it is called is generated outside (just outside) the event horizon, which is the limit within which nothing can escape the black hole. A particle and its antiparticle are "promoted" from the quantum vacuum by the gravitational energy of the black hole. One of them falls into it, and the other escapes. Because creation of the pair took some of the black holes's energy, and only half of it came back through the infalling particle, the black hole's gravity, and hence its mass, is diminished.
  5. Feb 9, 2005 #4
    So I would be correct in assuming that none of this radiation and whatnot occurs once objects have crossed the event horizon?
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