After looking at all the formulae re black holes, I have another question: If you could somehow accelerate 2 approximately equal black holes in a counter-rotating ring like CERN and have them smash into one another, what would happen? I'm talking about _pure_ GR here, so I'm not concerned about all of the cascade of random particles that you'd get just from a high energy collision, but I'm interested in what happens to the black holes themselves. I can think of 3 possibilities: 1. The black holes merge, producing one extremely fast rotating black hole. 2. The black holes miss one another, but scatter elastically, generating a significant gravitational wave. 3. The black holes rip one another "apart" (whatever that means), producing a shower of smaller black holes. I'm particularly interested if there are any solutions in GR of type 3.