How did Stephen hawking prove that black holes are actually white?

Answer 1

Professor Hawking didn't really prove black holes were white. One of his famous contributions to black hole theory is that black holes interact thermodynamically with the universe (as if they have some intrinsic temperature relating to entropy) and can emit antiparticles near the event horizon which "drain" energy and thus, per mass-energy equivalence, drain mass from the black hole, and over long periods of time could cause a black hole to "evaporate" entirely. The radiation is now called Hawking radiation. So maybe in a strict sense one might call them "not entirely black" instead of using the term white.

The term "white hole" does appear in astrophysical theory but relates to an entirely different, and, to date, unobserved phenomenon notionally the opposite of black holes which can only emit matter, and which, although they add a parity or symmetry to the black hole theory, are considered somewhat speculative.