Numerical Relativity 102: Simulating fast binary black hole collisions on the GPU
Hello! Today we’re going to do one of the coolest things in all of physics in my opinion, which is simulating the collision of two black holes. Last time round, we implemented most of what we’ll need to simulate this, so today’s job is to capitalise on that and finally smash some black holes together. I’d highly recommend reading the prior article first
If you’re looking for someone with a lot of enthusiasm for GPU programming, and who’d rather love to do a PhD in numerical relativity - please give me a shout! 1
It’s worth taking a minute to understand what a black hole actually is, and why it’s such a difficult road to simulate them numerically. In general relativity, a black hole is a stable, self supporting configuration of spacetime, which propagates itself indefinitely. It does not require any matter to support it, nor necessarily to even form it. The spacetimes we are dealing with are vacuum solutions - there’s no matter of any description here
The event horizon itself acts completely normally in general relativity, but it is the singularity which causes problems for us. It is a true mathematical error, and we cannot simulate it by any means. Because it will always form no matter what we do2, we must come up with some method for dealing with it
