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Is a black hole considred a black body?

  1. Jun 25, 2009 #1
    Is a black hole considered a black body?
     
  2. jcsd
  3. Jun 26, 2009 #2

    Wallace

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    The Hawking Radiation that black holes are supposed to emit (though this hasn't been directly observed yet I believe) has as black body spectrum. In that sense a black hole behaves like a 'black body', although perhaps there are other characteristics of the formal definition of a black body that a black hole does not satisfy? I'm not sure.
     
  4. Jun 26, 2009 #3
    Current theory is that you CAN consider it that way. It just has a really low emissivity coefficient (which also happens to vary with its size) AND all non-rotating black holes of the same size have the same temperature, and rotating ones are hotter.
     
  5. Jun 26, 2009 #4

    George Jones

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    As Wallace and fleem have noted, Hawking showed that black holes radiate in (close to) black body-like fashion. Taking a black hole to be a black body and using some hand waving leads to

    https://www.physicsforums.com/showthread.php?t=205711.
     
  6. Jun 27, 2009 #5

    Chronos

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    It's really not a good analogy. A blackbody is an entity in classical physics. A black hole is a construct of general relativity. It posseses some of the same properties, but is not of the same species.
     
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