There is one piece of information that makes me wonder why finitely sized black holes are even possible: to an observer from afar, anything that approaches a black hole's event horizon is never observed to cross the event horizon, instead asymptotically approaching.
If that is indeed the case, then that would suggest that, for the generation of a black hole, the instance an event horizon arises from a singularity, surely, to outside observers, no more mass should be observed to cross that infinitesimal event horizon. Therefore, that would suggest that no more mass contributes to the singularity, and the mass of the singularity does not change. Therefore, the event horizon would remain infinitesimal in size, and no black holes would have the opportunity to grow to a size that any outside observers could observe in the first place.
This, of course, seems to be unlikely, given how black holes have indeed been detected. Therefore, I suspect there is a flaw in my logic, or that I'm making an incorrect assumption. However, I do not know where the flaw lies.
For example, perhaps the initial formation of a black hole does not start off with an infinitesimally sized event horizon. I assume this as I thought the generation of an event horizon occurs instantaneously whenever enough mass is collected within a certain volume.
Perhaps objects do indeed pass the event horizon, but only after an extremely long time passed.
Or could it be that objects just at the event horizon contributes to the mass of the black hole, even without passing through, until the event horizon grows in size and eventually consumes that which was just beside the event horizon.
Or, as a wild afterthought, is it feasible for black holes to have existed since the very start of the universe?
Any help with this would be very much appreciated!
