The theory of the Big Bang - how the Universe exploded from an infinitesimal speck to create matter, radiation, time and space. Within the first trillion-trillion-trillion of a second, the cosmos grew a hundred million times to less than the size of an atom. Then, in another instant, the Universe was the size of a galaxy. Now, 14-billion years later and strung alon vast filaments, the Universe has some 50 billion galaxies that continue to expand - and where stars are born, live and die.