We conventionally think of time as something simple and fundamental that flows uniformly, independently from everything else, from the past to the future, measured by clocks and watches.

In the course of time, the events of the universe succeed each other in an orderly way: pasts, presents, futures.

The past is fixed, the future open. . . . And yet all of this has turned out to be false.

Carlo Rovelli is Director of the Quantum Gravity Group of the Centre de Physique Théorique (CPT) of the Aix-Marseille University and author of 'The Order of Time', he joined Jonathan to discuss.

First aired 21/7/2018