NOVA

PBS | 9:00 pm

This five-part limited series concludes with "NOVA Universe Revealed: Big Bang," a finale that looks back at the moment many people think of as the moment the universe — and even time itself — started. That notion raises a related question that's a real head-scratcher, though: namely, what existed before the universe was born? This episode winds back the ages using animation based on stunning images from the Hubble Space Telescope.