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, fresh from graduate school at Berkeley, set out to fill in this gap in human knowledge. Leading a small team of researchers at Columbia University's Goddard Center for Space Studies, John Mather devised a proposal for a satellite, the Cosmic Background Explorer (COBE), to measure the microwave...