Why does time only ever move in one direction? We talk to philosophers of physics Jeremy Butterfield and David Wallace, as well as the eminent Roger Penrose about the puzzle time poses to physicists and what it has to do with the Big Bang and the second law of thermodynamics.
This podcast featuring Paul Davies, a theoretical physicist and cosmologist at Arizona State University and Director of BEYOND: Centre for Fundamental Concepts in Science, explores this difficult question and accompanies our What is time article.
Atomic clocks are the best time keepers, but need to be kept incredibly cold. Paradoxically, the cooling is achieved by shining light on them.
Fundamental physics says time is symmetric - so why does time move forwards for us in a block universe?