Hawking radiation is on pretty firm ground, even if (gasp) black holes don't exist. Hawking was even able to cogently explain the spectrum of the radiation over time (long wavelength early on and increasingly shorter wavelength radiation as the mass of the black hole decreases).
It's just the timescale of all of this that is so daunting. In the current era of our universe, no black hole is actually getting less massive. Even a black hole totally isolated in the depths of intergalactic space and deprived of all matter to ingest will still absorb the current 2.73K degree cosmic background radiation faster than it will emit Hawking radiation, so no black holes are shrinking now, and it will be an extremely distant epoch of our universe before they can start doing so. EXTREMELY distant.
(I'm assuming 'mini primordial black holes' don't exist, if they do, a few might be emitting enough radiation now to be shrinking, but don't hold your breath on them existing)
It's just the timescale of all of this that is so daunting. In the current era of our universe, no black hole is actually getting less massive. Even a black hole totally isolated in the depths of intergalactic space and deprived of all matter to ingest will still absorb the current 2.73K degree cosmic background radiation faster than it will emit Hawking radiation, so no black holes are shrinking now, and it will be an extremely distant epoch of our universe before they can start doing so. EXTREMELY distant.
(I'm assuming 'mini primordial black holes' don't exist, if they do, a few might be emitting enough radiation now to be shrinking, but don't hold your breath on them existing)
