There's lots of other questions on the forum about 2 black holes, but I think this is different - and I can't get my head around which outcome is consistent with GR. Black holes here are simplistic - non-rotating and let's assume with a tiny accretion disk; just enough grains of matter to allow us to see the black hole, but small enough to ignore when we are talking about the effects below. So in the basic case of an object (usually an unfortunate individual) falling into a black hole, what we see from the outside is that object slowing as it approaches the event horizon, never actually passing the event horizon and eventually pausing at the horizon, and then slowly fading from view. So here's my question. I have two black holes (as per my conditions above) and they start at some random distance from each other but are stationary with respect to each other - i.e. not orbiting, no rotations. etc. As they move together under their own gravitational influence, what will I see when they collide? Thought 1: The simple "unfortunate individual" case is still a two body problem, so extending the thinking would suggest that the accretion disks would meet, and I would never actually see the two holes combine. Though 2: Thought 1 is nonsense! I would see something akin to the models I've seen of two galaxies colliding - the two black holes will pass through each other, dance around a bit and end up as a single black hole, with the matter forming the accretion disks simply being scattered and then re-accreted during the process. Any views?