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Interaction of 2 black holes

  1. Nov 14, 2007 #1
    What would the concequence of 2 black holes moved to a certain distance appart with one being say double or triple the mass of the other. Would the force (or could the force) be strong enough to warp space back so that it 'destroys' the event horision therefore returning the black hole to regular matter or whatnot.

    Can you reverse a black hole?
  2. jcsd
  3. Nov 14, 2007 #2

    Chris Hillman

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    To repeat something several of us have recently had occasion to say: using a spellchecker would be a good idea.

    Is your question: what would happen if two black holes, one twice the mass of the other, encounter each other at a certain initial distance and relative velocity?

    The short answer is that exact solutions modeling such an event are in general hard to come by, but numerical simulations have been developed into an art form; for an authoritative discussion of simulations of black hole formation see this eprint by Stuart Shapiro and for a discussion of black hole-neutron star binaries see this eprint by Shapiro et al.

    Event horizons are not physical surfaces and this kind of question is tricky to discuss for other reasons as well. But the short answer is that while in a close encounter between black holes their horizons become distorted, they are certainly not destroyed.

    Our gold standard theory of gravitation, gtr, is a relativistic classical field theory. In this theory, once a black hole is formed, it cannot be destroyed. However, Nature adores the quantum, so it is natural to try to incorporate ideas from quantum field theories into gtr. As yet, this cannot be done rigorously, but roughly speaking there are fairly well understood but limited approximations which lead to the idea of Hawking radiation, and to the suggestion that black holes might very very slowly evaporate. It is important to understand that a stellar mass black hole would take a very long to evaporate if this suggestion turns out to be correct!

    So the best short answer to your question is probably: as far as we know, no, but over very long periods (much longer than the current age of the universe), possibly yes.
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