What happens if a black hole falls into another black hole.

Question: What happens if a black hole falls into another black hole.
- Keywords:
  black hole,
  merge,
  super black hole
Asked by thomasm to Manolis on 11 Mar 2014.
- Manolis Rovilos answered on 11 Mar 2014:
  
  This is a very interesting question! The answer is that we have not seen anything like that yet, but theory says that they will merge releasing huge amounts of energy in a never observed form called gravitational waves. ESA, the european Space Agency is planning to spend more than a billion pounds to send a satellite into space to observe this phenomenon for the first time, and everyone is really excited about that!

Question: What happens if a black hole falls into another black hole.