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What is the size of a black hole?

  1. Jan 31, 2012 #1
    If Planck length is the smallest size, does that mean a black hole would get compressed down to the Planck scale, but no further or can the black hole really have zero size like an electron?
  2. jcsd
  3. Jan 31, 2012 #2
    According to many string theories, the planck size is the limit---and thus a BH's center would indeed be about that size, and not a true singularity (as general relativity suggests). The answer is unknown.

    1) Black-hole refers to the entire object, specifically the event horizon---not just the central singularity
    2) Electrons have a finite (non-zero) size.
  4. Jan 31, 2012 #3


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    The term 'singularity' is math speak for 'we don't know'. It is the point where our math ceases to yield intelligible results. We know the chunk of matter hiding behind an event horizon is smaller than the event horizon [duh]. A good guess would be some multiple of planck lengths, but, that is still just a guess. We probably need a theory of quantum gravity to get the right answer.
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