Can black holes even collide? I guess their horizons can merge somehow... Probably a spectacular show.

Disclaimer: This is my own work

https://www.youtube.com/watch?v=doS85Mh78Vc

This is what they look like when they merge, its pretty darn cool

That’s precisely what LIGO measures, the gravitational waves from black hole mergers (or neutron star mergers, etc).

>Cosmic Heavyweights Collide – LIGO Detects Largest, Fastest-Spinning Black Holes Yet

https://scitechdaily.com/cosmic-heavyweights-collide-ligo-de...

I love to contemplate galactic-scale synchrotrons that accelerate supermassive charged black holes to collide at relativistic speeds. The thought never really goes anywhere, but I'm sure it'd be a spectacle to behold.

It would be just about the only way we could get the data required to resolve the contradictions between the Standard Model and general relativity. The unification energy is simply stupendous.