We know the universe had a beginning, and expanded from a state of unimaginable density to an all-encompassing cosmic fireball to a simmering fluid of matter and energy. This laid down the seeds for everything from black holes to one rocky planet orbiting a star near the edge of a spiral galaxy that happened to develop life as we know it. But what happens at the end? Mack takes us on a tour through five of the cosmos's possible finales. Along the way she guides us through cutting-edge science and major concepts in quantum mechanics, cosmology, string theory, and much more.