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Dark Radiations

  1. Oct 17, 2003 #1
    Prof.Stephen Hawkings has proved that black holes shine with dark radiations.
    How is this possible when even light cant escape a black hole? What is the nature of such radiations?
  2. jcsd
  3. Oct 18, 2003 #2
    Do a web search and you'll find a lot from there. Alternatively, you can read his books.

    I do not know the details, but I know that at the event horizon, there is quantum fluctuation in the vacuum, hence causing matter and their antimatter counterpart to form for a split second, before annihilating again. For some reason which I'll leave it for others to explain (because I don't know), there is a very small chance that the one with negative mass will fall back into the black hole.

    According to E = mc², since the black hole gained negative mass, it experience a drop in energy, and hence the energy that's lost must be due to the particle that has escaped.
  4. Oct 18, 2003 #3


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    It's called Hawking radiation and is to do with the fact that black holes must be consitent with the laws of thermodynamics. Stephen Hawkings suggested the mechanism that P. described above, there are other ways to think of it though, for example you can think of it as particles tunelling through the potential barrier of the black hole.
  5. Oct 18, 2003 #4


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    The tricky part is that nothing is actually escaping the black hole. The virtual particles referred to by Pandemonium form exactly on the event horizon. If one virtual particles forms just inside the event horizon, and its meet forms just outside, then the one that forms outside cant escape. It does not cross the event horizon; it came into existence already outside the black hole. However, energy generated by stresses on the fabric of space-time (caused by the black hole's gravitational gradient) is the energy which formed in both virtual particles. So, when one of them escapes, 1/2 of the energy expended to generate them is lost. This virtual particle has now become a real photon (for example), and radiates away from the black hole. As a result, the black hole loses mass.
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