The Arrow of Time

A candle burns down; it doesn't 'unburn' up. Time appears to flow, bringing us a future, mysterious and potential; it carries away events into an unchangeable past. We remember the past but can only guess at the future. Time's arrow points one way.

However, to the atoms in the candle and the air, time looks the same backwards or forwards. 'Unburning' is allowed by their laws of motion. Is the arrow of time an illusion?

Even more perplexing: Einstein's time is laid out like a map in an 'eternal present' - is free will an illusion too?

This talk discusses irreversibility and causality with ideas from thermodynamics, cosmology and quantum theory.