Greg Egan on Nostr: OK, Alice jumps first, followed by Bob. Bob does not see light from Alice at the ...

OK, Alice jumps first, followed by Bob.

Bob does not see light from Alice at the moment she crossed the horizon until he, too, is crossing the horizon. He certainly doesn’t see her pinned to the horizon and fading away from redshift, as he would have if he didn’t fall himself and just stayed at a fixed distance from the horizon.

But I don’t know why you think the horizon “recedes”. Alice recedes from Bob, because she fell first. He reaches the horizon himself in a finite time by his own personal clock, and at that point he sees Alice at the moment she crossed the horizon.