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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.

Lewis Miller
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  • 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). –  Aug 03 '16 at 19:57
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    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. –  Aug 03 '16 at 20:08
  • 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. – kpv Aug 03 '16 at 22:51
  • 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. – Bob Bee Aug 03 '16 at 23:57
  • @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 – Lewis Miller Aug 04 '16 at 03:15
  • Comment continued: is probably wrong. My intuition was based on concepts that don't apply to general relativity. – Lewis Miller Aug 04 '16 at 03:25
  • @LewisMiller. Agreed. I came to the same conclusion on mine – Bob Bee Aug 04 '16 at 03:31
  • @LewisMiller. BTW, I see you got the PhD at UF in 71. I got my MS there in 67, my PhD at Berkeley in theoretical physics (yes, general relativity) in 72. But have not practiced it since 76, just caught up in the last 2 years so am still a bit rusty. I caught up with QFT also, but still also a bit rusty. Who was your prof at UF? Mine for the MS was Green. – Bob Bee Aug 04 '16 at 03:39
  • OK I have now suggested this as a duplicate: that's not intended as a hostile act, just because it looks like we agree it is. –  Aug 04 '16 at 04:49
  • @tfb I agree. No offense taken. – Lewis Miller Aug 04 '16 at 12:30
  • @BobBee I arrived at UF in 1966 and also got my degree under Green (in nuclear physics), but didn't start working for him until the summer of 67 (probably about the time you left). So we overlapped but likely had only hall way encounters. – Lewis Miller Aug 04 '16 at 14:11
  • @BobBee BTW Sorry I duplicated your question. I was reading SE on a daily basis until warm weather arrived and I shifted my endeavors to gardening. Your question must have slipped by me while I was working outside. – Lewis Miller Aug 04 '16 at 14:19
  • No problem, nobody can keep track of all the posts and stay sane. I'm not bothered much by duplicates, mainly on a topic where the answers are never really perfect and people have third doubts. I only pointed out my question so you could see it. I'd encourage you to ask for more clarification and explanation on anything still not clear, those are not really triviall nor physically totally resolved issues. – Bob Bee Aug 04 '16 at 17:19
  • Yes, summer of 67 was when I left. Real coincidence. I ran in my previous job into Ravi Sharma who also got the PhD with Green, can't remember the exact timeframe but I also didn't know him then – Bob Bee Aug 04 '16 at 17:22
  • $BobBee Sharma left a while before I arrived. I think l met him once when he returned for a conference. – Lewis Miller Aug 06 '16 at 18:10

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