7th Hermann Staudinger Lecture: "Why Can't Time Run Backwards?"
Nobel Laureate Anthony Legget (University of Illinois at Urbana-Champaign)
We can all tell when a movie of some everyday event, such as a kettle boiling or a glass shattering, is run backwards. Similarly, we all feel that we can remember the past and affect the future, not vice versa. So there is a very clear "arrow" (direction) of time built into our interpretation of our everyday experience. Yet the fundamental microscopic laws of physics, be they classical or quantum-mechanical, look exactly the same if the direction of time is reversed.
So what is the origin of the "arrow" of time? This is one of the deepest questions in physics. Anthony Leggett will review some relevant considerations, but he does not pretend to give a complete answer.