Particle physicists explore the microworld of the atom; cosmologists study the universe on a large scale. This study follows the merger of these fields as the authors seek to define the "theory of everything". It describes the development of the current views of the nature of space, time, matter and fundamental forces, and explores what these views reveal about the formation of the universe. The text expands on some of the discoveries of 20th-century science, the explorations of inner space and outer space, and of the promises they hold for decoding beginnings, ends and the ultimate laws of nature.