Melvyn Bragg and his guests discuss Einstein's theories of relativity. Between 1905 and 1917 Albert Einstein formulated a theoretical framework which transformed our understanding of the Universe. The twin theories of Special and General Relativity offered insights into the nature of space, time and gravitation which changed the face of modern science. Relativity resolved apparent contradictions in physics and also predicted several new phenomena, including black holes. It's regarded today as one of the greatest intellectual achievements of the twentieth century, and had an impact far beyond the world of science.With:Ruth Gregory Professor of Mathematics and Physics at Durham UniversityMartin Rees Astronomer Royal and Emeritus Professor of Cosmology and Astrophysics at the University of CambridgeRoger Penrose Emeritus Rouse Ball Professor of Mathematics at the University of Oxford.Producer: Thomas Morris.