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- TL;DR Summary
- Are the black holes we’ve observed actually “almost" black holes, i.e. indistinguishable from the mathematically idealized form of a black hole?
My understanding from General Relativity is that if as distant observers we watch a probe or any test mass approach a black hole, time dilation goes to infinity as the probe gets closer to the event horizon. This would imply that we would never observe a black hole form, or the collision of two black holes. I understand though that if we look at the proper time of the probe, it will cross the horizon briefly, with it's clock ticking as normal in its own frame. This would mean a black hole has no trouble forming or colliding with another black hole. However, since these events would take an infinite amount of time here in our Earth frame of reference, how has the Event Horizon Telescope observed a black hole? In addition, how has LIGO observed the resulting gravitational waves of colliding black holes? In my searches, I haven't found any clear answers to these questions, but the only resolution I have come up with that reconciles these issues is that the black holes we have observed are not "true" black holes in their mathematically idealized form, but rather "almost" black holes. By "almost" black holes I mean that the distribution of mass is so close to that of a "true" black hole that from an observational standpoint, they are both indistinguishable and we may as well regard these "almost" black holes as actual black holes. Is this correct or do I appear to be making any false assumptions here? If this is correct, this would mean that no "true" black holes actually exist?