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That's not true. You can check out chapter 32 in Misner's Gravitation for a detailed discussion of a free falling observer's worldline into a black hole.
by sigmoid10 2y ago
That's not true. You can check out chapter 32 in Misner's Gravitation for a detailed discussion of a free falling observer's worldline into a black hole.
- jiggawatts 2y agoIn that section "infinite" is used a bunch of times, which is a non-physical simplification. All of the sections using Penrose diagrams talk explicitly about "the point at infinity", but Hawking showed that black holes don't last for infinite time. You have to keep reading past the overly simplified models. E.g.: right after that section: "But from an external vantage point the star requires infinite time to reach the horizon". In other words, observers don't ever see a black hole form completely, which is an observation that infalling observers can't contradict. Either you believe that there are two different universes for non-infalling and infalling observers, or you have to accept a single physical reality that black holes never completely form, and then evaporate in a finite time.
- sigmoid10 2y agoYou would not see matter falling through the horizon, but you would see the horizon grow beyond the point where you last saw the infalling matter. Just look at the diagrams. People have also done numeric simulations of this for realistic spacetimes, I believe you can find several of them on the LIGO websites. There are some mysteries here, but black hole formation and growth is not one of them.