This business of things stopping at the event horizon came up before in a discussion here. If the speed of light falls to zero at the event horizon, then nothing can cross the event horizon, ever. Light and matter simply goes more and more slowly, effectively stopping, although it's never technically a complete halt.I agree that we’re probably wrong about painting the picture just like this. I’ve heard that the official physics line says that things actually do fall in, but a description of how/when from the POV of various frames is typically omitted. The book from Thorne recommended above perhaps covers this.
From my naive view, one can drop some material ‘on’ a black hole, which gets stuck when time dilates to nothing, but drop anything else and the event horizon expands just enough and swallows the earlier material. That sounds pretty wrong, but at least it gets stuff in there, and allows the original hole to form in the first place.
On another note is the observed behavior of the merger of two black holes, where one gets to observe something big fall in. The gravity waves come slow at first but with increasing frequency, getting higher and higher until a brief ‘chirp’ at the end when the waves cease abruptly. That’s a view from a distant frame, and yet it speeds up at the end. If it got stuck on the surface, wouldn’t the waves slow to imperceptibility instead of speeding up? This pattern was predicted before it was first witnessed.
On the ‘freeze’ front, I think it was Hawking that was disturbed by the seeming violation of conservation of information when things fell into a black hole, but this was solved by realizing that from any external moment in time, the information never makes its way in, and is thus not actually lost.
I’m just pointing out what I see is evidence on both sides of this fence.
The reason many people imagine that a space ship could cross the event horizon of a large black hole while the people inside it continue to live normally is that the lack of Newtonian time in GR (and SR) leaves the "time" dimension as the only kind of time in the model, and that provides no mechanism to allow any clocks run slow, so for the people in the space ship their clocks must keep on ticking at full speed. However, they will be systematically annihilated before they reach the event horizon because they'll actually be stuck there for countless billions of years while the black hole gradually evaporates - the mechanism behind Hawking radiation will eliminate every single piece of their matter.The surviving the crossing is hypothetical. You’re right in that the radiation there (which is only considered Hawking radiation if part of it escapes permanently) would likely explode our traveler as he compresses years of intense radiation into a millisecond. The gravitational field inside is even more intense, and barring a description of the physics there, it is guesswork if a biological being could exist. The comment was just to point out that little black holes kill you via tidal forces before you ever get that close. The big ones need to use different means to kill you.
The part of the ship clock ticking at full speed is correct. Except for the clock exploding in a radiation cloud, there would be no discontinuity or anything from a temporal standpoint.
It looks to me as if the only matter that can ever get into a black hole is the matter that collapses to form a black hole, and most of the material of a collapsing body will miss the party and end up sitting just outside the event horizon of the first part to become dense enough to become a black hole. Also, if multiple parts form separate black holes during the collapse of the body, those separate parts may not be able to merge because there may be material around and between them which cannot reach/cross any of the event horizons, so I predict that you'd actually end up with a set of black holes stuck together which collectively form a sphere, but which remain distinct from each other (and the same would happen with any black hole merger).By that logic, all black holes would be of no size, each preventing additional mass upon reaching the threshold. For that matter, each would then immediately evaporate, preventing actual formation of black holes.
So the view of stuff getting stuck on the surface is probably wrong, at least when worded that way. I’d appreciate if somebody more informed (perhaps the answer from the book) would chime in.
All the above is dependent on the idea that the speed of light reaches zero at the event horizon. Perhaps it only reaches zero outwards though.I think the answer lies on this front. The event horizon of a BH is very much like the edge of the Hubble Sphere. Time there is stopped relative to us and the big bang is still banging, because space itself (not just the matter) is moving away at lightspeed. That is dilation due to relative speed, not gravity, so the analogy might not be appropriate. I know it is invalid to apply the rules of an inertial frame over distances large enough for space to not be flat.
If [lightspeed] remains higher than that inwards, then there would presumably have to be a mismatch between the speed of light up vs. down at all altitudes in a gravity well.Doesn’t much matter if time is dilated to zero. Insufficient speed isn’t the problem. Light speed going down could be 3c, but it isn’t going to help if it has no time to go anywhere.
Bottom line is I don’t know the answers. I’m no GR expert.