At the heart of the Milky Way lies a supermassive black hole 4 million times more massive than our Sun. A place where space and time are so warped that light is trapped if it ventures within 12 million km. According to Einstein, inside lies the end of time. According to 21st-century physics, the reality may be far more bizarre. Black holes lie where the most massive stars used to shine and at the edge of our current understanding. They are naturally occurring objects, the inevitable creations of gravity when too much matter collapses into not enough space. And yet, although the laws of nature predict them, they fail fully to describe them. Black holes are places in space and time where the laws of gravity, quantum physics and thermodynamics collide. Originally thought to be so intellectually troubling that they simply could not exist, it is only in the past few years that we have begun to glimpse a new synthesis; a deep connection between gravity and quantum information theory that describes a holographic universe in which space and time emerge from a network of quantum bits, and wormholes span the void. In this groundbreaking book, Professor Brian Cox and Professor Jeff Forshaw take you to the edge of our understanding of black holes; a scientific journey to the research frontier spanning a century of physics, from Einstein to Hawking and beyond, that ends with the startling conclusion that our world may operate like a giant quantum computer.