Gerardus 't Hooft - Unitarity in the quantum black hole

Talk at Quantum gravity and quantum information held at CERN, Mar.18-22, 2019.

Enjoy!

[stargenemolly]

I think that in restricting to very small time scales, 't Hooft is actually recognizing
a kind of invariant, so that the eternal, static BH picture is sufficient. In the same
way that Einstein saw that the invariants of GR held, as long as he confined
his analysis to sufficiently small volume elements in a g-field.