Quantum Mechanics at the Black Hole Horizon

Gerard 't Hooft, Utrecht University

At extremely tiny distance scales it seems that black holes will be hard to distinguish from the other elementary particles. This is why the study of black holes will be necessary if we want to understand that domain of physics, where perhaps the `ultimate laws of physics' originate. This motivates us to try to understand as accurately as possible the physical laws controlling black holes and elementary particles, and to study the restrictions posed by quantum mechanics on the black hole horizon. Even the task to devise just any `reasonable' theory appears to defy our imagination. We discuss information loss, hidden variables, and the special role played by `extreme black holes'.