Collision occurs when there is some sort of interaction between massy particles that try and fail to occupy the same space. Whatever stops you from passing through the floor counts as "collision".
An event horizon has no mass or other existence and cannot collide with anything. Within the black hole, there is mass somewhere, but generally not at the event horizon. If you're not comfortable assuming that, we can make it a definition - take this to be an example where none of the internal mass lies within the region of overlap.
What is the obstacle to the black holes separating again?
An event horizon has no mass or other existence and cannot collide with anything. Within the black hole, there is mass somewhere, but generally not at the event horizon. If you're not comfortable assuming that, we can make it a definition - take this to be an example where none of the internal mass lies within the region of overlap.
What is the obstacle to the black holes separating again?