We know the universe had a beginning. With the Big Bang, it went from a state of unimaginable density to an all-encompassing cosmic fireball to a simmering fluid of matter and energy, laying down the seeds for everything from dark matter to black holes to one rocky planet orbiting a star near the edge of a spiral galaxy that happened to develop life. But what happens at the end of the story? In billions of years, humanity could still exist in some unrecognizable form, venturing out to distant space, finding new homes and building new civilizations. But the death of the universe is final. What might such a cataclysm look like? And what does it mean for us? Here, Katie Mack unpacks these questions, taking us on a mind-bending tour through each of the cosmos' possible finales: the Big Crunch; the Heat Death; Vacuum Decay; the Big Rip; and the Bounce.