"[String theory] has led us in strange directions that we couldn't conceive of; it's revealed depths of mathematical structure that we couldn't have anticipated". Watch a video interview with Professor Michael Green, winner of the 2014 Fundamental Physics Prize.

Theoretical physicists are searching for a 'Theory of Everything' to reconcile quantum mechanics and relativity - the two great physical theories of the twentieth century. String theory is a current hot favourite, and some of the world's most eminent physicists tell us why.