Why can’t time run backwards?

Tuesday 24 November 2009

Nobel-prize winning scientist Sir Anthony J. Leggett will attempt to answer one of the deepest questions in physics when he visits St Andrews to give a public lecture later this week.

Sir Anthony – who was awarded the Nobel prize in 2003 for his work on superfluidity – will ask why time can’t run backwards in a much anticipated lecture, part of a high-profile series staged by the University of St Andrews involving Nobel laureates.

Leggett said, “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; I will review some relevant considerations, but do not pretend to give a complete answer.”

The lecture takes place on Friday November 27th at 4 p.m. in Lecture Theatre A, School of Physics and Astronomy, North Haugh, St Andrews.

The lecture is free, open to all and members of the public are warmly welcome to attend.



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