Question

Does black hole complementarity apply to white holes?

Answer 1

If physics is time reversal invariant, there ought to be white hole complimentarity as well. Imagine a white hole so enormous that it is possible for life to evolve entirely within it for billions of years before emerging to tell their story about the interior of the white hole. Meanwhile, an external observer can observe and keep note of everything in the vicinity of the white hole and what comes out of it. Both observers can meet and compare notes. Can the external observer really claim the white hole interior doesn't exist.

Answer 2

Black holes are the same thing as white holes. This has come up a hundred times. Time reversing an equilibrium state is still an equilibrium state. But this suggests strongly that emission from a white hole (at least in the non-rotating neutral state) is entropically forbidden, since it reduces the equilibrated horizon area by more than the entropy of the outgoing stuff.