Black holes and the reversibility of time

A basic principle of physics is that time evolution is always reversible: given knowledge of the present, we can reconstruct the past and predict the future. But it is a challenge to preserve this principle when we combine the theory of gravity, which predicts the existence of black holes, with quantum mechanics, which governs the microscopic world. This is a problem in theoretical physics, but also one that has philosophical implications. In this talk, we will discuss some recent progress on this problem