The Big Bang theory proposes that the universe we know emerged from a uniformly hot and impenetrable mass of protons, electrons and radiation. But until recently, we knew very little of the first stages of the 13 billion year process in which our cosmos took shape. In 1974, a young astrophysicist, John Mather of Columbia University's Goddard Center for Space Studies, devised a proposal for a satellite, the Cosmic Background Explorer (COBE), to measure the microwave background radiation in space. From temperature variations in the radiation emanating from different points in the universe,...