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Second law of thermodynamics and black holes ?

  1. Sep 25, 2009 #1
    second law of thermodynamics and black holes ?!!

    I am having a hard time thinking about the perservation of the second law of thermodynamics in black holes. If we throw a mass that have some level of disorder (entropy) into a black hole, it will disappear and that will appear to us as violating the second law of thermodynamics (entropy can only increase or at least remains constant in an adiabatic reversible process). yet some said (I think Hawking was one of them) that when B.H absorbs mass its area will increase and that is an indication that entropy is preserved inside a B.H. I have no problem accepting that, however, what if a B.H evaporates ? does that imply that entropy dicreased in our universe? can the second law of thermodynamics cease to be valid in B.Hs ?
     
    Last edited: Sep 25, 2009
  2. jcsd
  3. Sep 25, 2009 #2
    Re: second law of thermodynamics and black holes ?!!


    Negative.

    The entropy of an isolated system can only increase.

    If such a mathematical model predicts an affirmative result, then the mathematical model probably has been formulated incorrectly with respect to Thermodynamics and General Relativity.

    Theoretically with respect to Hawking radiation all the laws of thermodynamics are valid with all masses down to quantum particles and quantum Planck scales, where these scales themselves become quantum limits due to singularities.
     
    Last edited: Sep 25, 2009
  4. Sep 26, 2009 #3
    Re: second law of thermodynamics and black holes ?!!

    I see, so you're saying that given that Hawking's radiation are true, the second law of thermodynamics is valid, right ?

    I understand that Hawking radiation is one of the few theories that combine quantum mechanics with general relativity, but has it been validated yet ? or even can it be validated ?

    one more thing, I am curious to know what are the alternatives to the Hawking hypothesis that contradicts with the second law ?
     
    Last edited: Sep 26, 2009
  5. Sep 27, 2009 #4
    Re: second law of thermodynamics and black holes ?!!


    All the laws of thermodynamics are valid and therefore Hawking radiation is a valid theory based upon that consequence.

    Hawking radiation has not been observationally verified.

    Affirmative, by observing the radiation emitted by a Black_Hole or quantum Black_Hole particle.
    If such a mathematical model predicts an affirmative result, then the mathematical model probably has been formulated incorrectly with respect to Thermodynamics and General Relativity.
     
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