Conservation Of Information?

[koganbot]

Posting again on a subject I don't understand and never will: what physicists mean by "information." My brain balks at mathematical symbols, but I'm good at concepts; so my guess is that if some articulate physicist were to wander by, he or she could explain "conservation of information" in a way that doesn't totally leave me at sea. Wikipedia hasn

Comments

The explicit mechanism remains unclear

[koganbot]

This is from Sean Carroll, From Eternity To Here, p. 283; what he's calling "four-dimensional" is what I was calling "3 + 1 dimensions" (three of space, one of time, no gravity) in the previous two comments:

So we make a black hole in anti-de Sitter space and then let it evaporate. Is information lost? Well, we can translate the question into an analogous situation in the four-dimensional theory. But that theory doesn't have gravity, and therefore obeys the rules of ordinary quantum mechanics. There is no way for information to be lost in the four-dimensional nongravitational theory, which is supposed to be completely equivalent to the five-dimensional theory with gravity. So, if we haven't missed some crucial subtlety, the information must somehow be preserved in the process of black hole evaporation.

...But you can see that the argument, while seemingly solid, is nevertheless somewhat indirect. In particular, it doesn't provide us with any concrete physical understanding of how information actually gets into Hawking radiation. Apparently it happens, but the explicit mechanism remains unclear.
(And I'll reiterate on my own behalf that I don't have a concrete physical understanding of what "information" is, or what one means by saying that it's preserved. Also, how do we manage to inhabit five-dimensional anti de Sitter space to begin with?)