The latest developments in physics have the potential to radically revise our understanding of the universe: its make-up, its evolution and the fundamental forces that determine its operation. Knocking on Heaven's Door is an exhilarating and accessible overview of these developments and a rousing defence of the role of science in our lives. There could be no better guide than Lisa Randall: the bestselling author of Warped Passages is an expert on both particle physics (the study of the smallest objects we know of) and cosmology (the study of the largest) and is one of the most highly regarded theoretical physicists in the world. In Knocking on Heaven's Door she recounts the thrilling progress in our understanding of the universe from Galileo and Newton to Einstein and Feynman; she explores how we decide which scientific questions to study and how we go about answering them; and she examines the role of risk, creativity, uncertainty, beauty and truth in scientific thinking. Throughout, Lisa Randall explains with wit and clarity the latest ideas in physics and cosmology, including the aims of the biggest and most expensive machine ever built: the Large Hadron Collider, the enormous particle accelerator situated over a 100 metres below the French-Swiss border. More than 27 kilometres in circumference, it has within it the hottest spot in the galaxy as well as the coldest and features the most powerful supercomputer system of all time. One of the most illuminating science books in years, Knocking on Heaven's Door makes clear the biggest scientific questions we face and reveals how answering them could ultimately tell us who we are and where we came from.