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Black Hole

  1. Mar 11, 2006 #1
    Supposing I started off with a particle, which I know exactly the state it is in, hence, it is in a pure state. And hence also, its entropy is zero.
    Now, suppose we throw the particle into the black hole and be sucked in, then, then the area of the black hole increases and hence, the entropy of the black hole also increases.
    But, how can this be possible? I started off with a zero von Neumann entropy and why should the entropy/area of the black hole increase?
  2. jcsd
  3. Mar 11, 2006 #2


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    In most physical processes entropy increase, so why are you surprised?
  4. Mar 11, 2006 #3
  5. Mar 30, 2006 #4
    according to the 2nd law of thermodynamic, entropy cannot decrease..decreasing the chance of a whitehole possiblility.
  6. Mar 30, 2006 #5


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    If you started with a pure state, entropy increase is only possible if you allow for a violation of unitary time evolution. This problem is known as black hole information loss and points out an incompatibility between QM and GR.
  7. Mar 30, 2006 #6
    but i thought there is a theory that states that information cannot be lost or destoyed?
  8. Mar 30, 2006 #7


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    Information is lost in irreversible macroscopic processes. I think that the statement is that unitary time evolution of pure quantum states is a principle that should not be violated. In case of quantum field theory of black holes, it's violation is an indication that something is wrong in the theory. If you are interested in knowing more about this I would suggest to ask in the subforum "Beyond the Standard Model".
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