This book is the first serious, book-length study of the philosophical implications of relativity. It explains the relevant technical issues of general relativity theory and discusses how these issues bear upon philosophical problems about the nature of space and time, causality and laws of nature. Features include an analysis of time travel, The Big Bang and the Horizon Problem, Eternal Recurrence and Cyclic Time amongst other much debated issues today which have been brought to light in the the face of a series of theorems, due largely to Stephen Hawking and Roger Penrose. Written by a leading philosopher, this book provides an overview of the technical literature as well as analytical commentary on its philosophical significance.