Now that LIGO has demonstrated that two black holes can burp large amounts of energy (in the form of gravitational radiation) in the process of consuming each other, shouldn't we stop saying that nothing can escape the event horizon of a black hole. Clearly, some of the mass energy that was observed in the LIGO experiment was confined by the event horizons of the two black holes prior to their merger. Somehow, in the transition from two separate event horizons to a single event horizon there was opened an escape route (if only for a short time).

I realize that Hawking radiation allows an evaporation of energy from a black hole, but that is a very slow process. Unless I am mistaken, LIGO-like events provide an avenue for prompt release of large amounts of energy.

  • $\begingroup$ No, we shouldn't. The easiest way of thinking about this is to regard the energy that escapes in radiation as having come from the gravitational field outside the horizons of the colliding objects. This can be made precise but it's fairly hairy to do so hence this being a comment not an answer (also, I suspect this may be a duplicate question). $\endgroup$
    – user107153
    Aug 3, 2016 at 19:57
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    $\begingroup$ I'm not voting to close this but it is at least close to a duplicate of this: perhaps someone with better search skills than me can find a better candidate fir a duplicate. It's a good question to ask though, as the answer is subtle. $\endgroup$
    – user107153
    Aug 3, 2016 at 20:08
  • $\begingroup$ What stops anything from escaping the EH? It is gravity. So, I am not sure if the rule should apply to gravity itself, or its waves. $\endgroup$
    – kpv
    Aug 3, 2016 at 22:51
  • $\begingroup$ The link that @tfb refers to was my question, and there are answers there that answer every point made. There are also great comments. All by people other than me. I had misinterpreted the same issues that Lewis Miller also refers to, and also due to LIGO. I recommend those answers. I've since researched it more. Indeed BH mergers can release huge amounts of energy, and the maximums possible are also well known from Hawking-Bekenstein entropy and area relationships. For LIGO about 4-5% was released. Numerical relativity also estimated the same number. $\endgroup$
    – Bob Bee
    Aug 3, 2016 at 23:57
  • $\begingroup$ @BobBee after reading your question and the answers and comments, I see that my intuition that some of the radiated energy came from inside the EHs $\endgroup$ Aug 4, 2016 at 3:15