Comment by Gravityloss 6 months ago
Well yes for example if there was a cannon firing an apple from the moon, then it would travel the same trajectory, just in reverse.
But we know there are no apple firing cannons on the moon.
Ie if an object was coming from the moon and its past trajectory intersected with the moon's surface, you could say "this is reverse video".
Maybe this thought experiment makes it clear. There's a cannon firing straight up from the lunar pole. One cannot observe the explosion charge. The ball goes straight up, and then falls down and goes back to the barrel. The cannon is filmed from afar firing and you can see the whole ball travel.
Then you are shown two films, the normal and a reversed one. Would you be able to tell which one is which, and if so, how?
That was exactly my point, that an apple coming from a black hole may seem problematic but so does an apple coming from the Sun. I don't see an essential difference regarding the "reversibility" of the physical process (but I could be wrong).