I don't know, but then I never proposed what you describe.
You said this:
Indeed. And in my interpretation, the white hole - if one exists - is indefinitely far into the future. So we wouldn't expect observe such a thing.
You also said this:
There could be a discrepancy there, and we'd have no way to know it, because we cannot know exactly how much mass has fallen into a black hole in order to give it its present mass.
I'm assuming this doesn't mean "the mass that has fallen into the black hole from the moment it first appeared", as that wouldn't be scientific. We can't travel backward in time, as far as we know, so we wouldn't be able to observe this, unless, by some stroke of luck, we happened to find a star that was just about to collapse into a black hole and studied it for decades.
"Relatively speaking" can mean a lot of things. What did it mean when you used it here? Relative to what?
Surprisingly enough, I thought this was the problem, but dismissed it, as you don't tend to make mistakes like that. I didn't say "relatively
". I said "relativity
". See here:
This is relativity speaking. We can't directly observe spacetime, as far as I know.
Where would we observe it coming out? Inside of existing black holes? I'm not the random-white-hole-appearing-in-random-places advocate.
White holes are the "end" of a black hole's gravity well. It has to be this. Either that or you're suggesting that black holes and white holes are the same (that is, that the properties scientists expect from white holes are not true, which would explain why we've never observed white holes, per se
), in which case I'd have to quote (maybe even screenshot, should you not believe it) a PM I sent from myself to myself several hours ago expecting this exact statement.
I know. And QFT only works in a locally flat-as-a-board spacetime.
How "locally" are we talking? Because all things are flat as a board if you look at it at a small enough scale (but not too small, such as atomic scale).
You should also read up on [wiki=Quantum field theory in curved spacetime]the extension of QFT to curved spacetime[/wiki].
In particle physics, quantum field theory in curved spacetime is an extension of standard, Minkowski-space quantum field theory to curved spacetime.
EDIT: I want to note that I was not aware that the standard QFT only applied to flat-as-a-board spacetime.