We are living in what is often referred to as the golden age of cosmology. The study of string theory has led to fast and furious progress being made towards the discovery of the long-searched-for Theory of Everything. If it comes, this theory will describe a universe very different from that which common sense suggests - a quantum univers in which time and space can be measured only relatively, and nothing is certain. In The Fabric of the Cosmos, Brian Greene shows why, explains how far we have come and speculates on how far we still have to go.