The Big Bang theory, based on speculations dating back to 1922 and confirmed by astronomers in the 1960s, posited that the universe began as a minuscule fireball of extreme density and temperature and that it has been expanding and cooling ever since. But the theory said nothing about what came before or even during the split second when everything went bang. In December 1979 Guth, then 32 and an obscure physicist at the Stanford Linear Accelerator Center, emerged as the first scientist to offer a plausible description of the universe when it was less than one-hundredth of a second old. During an unimaginably explosive period between 10-37 second and 10-34 second after its birth, Guth said, the universe expanded at a rate that kept doubling before beginning to settle down to the more sedate expansion originally described by the Big Bang theory.