How can a black hole grow in mass, if it takes an infinite time to cross the event horizon, for matter approaching the black hole (as seen from an outside observer far from the black hole)?
To make a black hole, one must concentrate mass or energy sufficiently that the escape velocity from the region in which it is concentrated exceeds the speed of light.
So , as seen from an outside observer, we have redshift and time dilation (all the GR effects in action ) for matter approaching the event horizon of a black hole.
Eventually (in finite time ), the outside observer sees sufficient matter (energy ) accumulating in a small neighborhood of the event horizon of the original black hole that other black holes must emerge (in the neighborhood of the event horizon of the original black hole ). So the outside observer sees a continuous merging of black holes , those formed in the neighborhood of the event horizon of the original black hole, and the original black hole itself. That could explain how a black hole can grow, even as seen from an outside observer.
Question. Is this explanation correct?
