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Question about proton decay and black hole evaporation

  1. Apr 16, 2010 #1
    Just to start, let me reassure you that I am not an LHC alarmist. I understand and agree with the cosmic ray explanation, i.e. earth, the sun, jupiter, and everything else would be a BH if they didn't evaporate.

    Anyway, I was reading around a little on wikipedia and came to this page: http://en.wikipedia.org/wiki/Virtual_black_hole" [Broken].

    So it seems like the various theories predict proton decay because of virtual black hole formation? That would explain why the predicted decay rates are so low. I take it that the virtual black hole thing is a result of the Heisenberg uncertainty principle with respect to energy and position. Am I correct about this? I recognize that virtual BHs may be a product of various unproven quantum gravities, but aren't they inevitable due to Heisenberg?

    The next thing I thought was, well, since proton decay seems to have been disproven by experiment, doesn't that also necessarily preclude a quantum description of gravity by definition? I mean, Heisenberg is central to quantum, and lack of proton decay would seem to say Heisenberg doesn't apply.

    So basically my final thought along this line was, if BH evaporation is based on effects derived from Heisenberg, then is it reasonable to assume that evaporation might in fact not occur? Or perhaps by a different mechanism altogether.

    Does any of this make sense? Or am I wildly off base with this? Thanks!

    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Apr 16, 2010 #2


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    Proton decay hasn't been disproven. However all evidence to date has been that if it does, it must have a half life > 1033 years. Essentially there is no evidence of decay.
  4. Apr 16, 2010 #3


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    I'm not overly familiar with the 'virtual black hole mediated proton decay', however, an absence of proton decays would merely put a bound on the fecundity of decay through this particular process.

    Additionally, the spacetime fluctuations giving rise to these black holes would need to be HUGE if they were to generate Planck mass virtual black holes. My guess is that we only expect such black holes in theories with lower scales of gravity, such as theories with large extra dimensions. But, there may not even be extra dimensions, and if there are, they may not be big. So, I think this type of decay is model dependent, and might not exist in nature to begin with.
  5. Apr 16, 2010 #4


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    I fail to see the relevance. There are no protons in black holes.
  6. Apr 17, 2010 #5


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    I think the relevance is that a black hole can eat a proton. What it burps out in Hawking radiation need not be a proton. This would look like proton decay. I think the idea is pretty crap, but that's pretty much the gist of it.
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