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Thermodynamics and black holes.

  1. Dec 17, 2007 #1
    I have been recently wondering about black holes and the laws of

    So I would like to ask:
    Can there be physical movement without thermal radiation in other words loss of
    energy in thermal form?

    Every particle in the universe that have mass will be in movement. I am
    in belief that black holes/singularity is not stationary objects so if
    they are in movement they should be radiating heat? If there is no
    particle without mass then there are no stationary particles in the

    Hawking radiation equals thermal radiation and radiated energy from the
    black hole in this case? That would mean: E=mc2+Hawking radiation then?

    I bet this have been discussed earlier so if you can point me a link to an answer i will look there...

    Last edited: Dec 17, 2007
  2. jcsd
  3. Dec 17, 2007 #2
    As one of the laws of thermodynamics states, each transformation of energy results in a loss of heat.

    Therefor something with kinetic energy will only give off energy when that energy changes form, i.e collides with something.
    Ofcourse this is not taking into account the energy already being given off by the mass itself.
  4. Dec 17, 2007 #3
    So is it safe to say then that there are no collisions between the particles inside the black hole? 0 friction?

    Can we say there is no collision without movement and backwards there are no movement without collision?
    Last edited: Dec 17, 2007
  5. Dec 19, 2007 #4


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    Staff Emeritus
    Science Advisor

    Where did you get the idea that "every particle in the universe that has mass will be in movement?

    It appears to me that you may have some fundamental misconceptions about thermodynamics that need to be addressed judging from the above statement :-(.

    The short version: While some sources such as http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/temper.html#c1 state

    this is not the definition of "temperature" used to describe the "temperature" of black holes.

    The defintion of "temperature" that is applicable to black holes, and that serves as the general defintion of the term is the equation relating the rate at which energy is converted into entropy.


    [tex]\Delta S = \frac{\Delta Q}{T}[/tex]

    Black hole entropy requires quantum mechanics and general relativity to understand, though a simple argument that suggests black holes have entropy is that if entropy always increases, when an object with entropy falls into a black hole that the entropy of the black hole must increase.
  6. Dec 19, 2007 #5

    jim mcnamara

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    Staff: Mentor

    Pervect -

    Thanks for a good answer.

    In the thread 'Are black holes cold' none of the answers implied that temperature of a black hole was in any way different from the first definition of temperature above.

    This answer clears up the correct but very incomplete information Janus gave in that thread, which made no distinction about temperature/entropy. My area is Population Biology, not GR.
  7. Dec 27, 2007 #6
    i totally agree with u . but the radiations emmited by the black hole cannot escape its event horizon due to its high gravity.more or less there r rotating as well as non rotating blackholes
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