Merging black holes generate gravitational waves – the target of the recently successful LIGO experiment. But generating such a wave takes energy – a lot of it, as reported in NewScientist (18 June 2016):
The second signal, called GW151226, also came from a pair of black holes merging. But these were much lighter – about 14.2 and 7.5 times the mass of the sun. They merged to form a black hole of 20.8 solar masses, meaning about 1 solar mass of energy radiated away in gravitational waves during the collision.
“This event radiated the equivalent of the mass of our sun in a couple of seconds,” [Salvatore Vitale of MIT] says. “Our own sun radiated about a millionth of its mass in 5 billion years. This really gives you the scale of how violent and sudden this release of energy is, as compared to our everyday experience.”
That’s a lot of energy.
