From the best-selling author of The Elegant Universe and The Fabric of the Cosmos comes his most expansive and accessible book to date -a book that takes on the grandest question: Is ours the only universe?There was a time when "universe" meant all there is. Everything. Yet, in recent years discoveries in physics and cosmology have led a number of scientists to conclude that our universe may be one among many. With crystal-clear prose and inspired use of analogy, Brian Greene shows how a range of different "multiverse" proposals emerges from theories developed to explain the most refined observations of both subatomic particles and the dark depths of space: a multiverse in which you have an infinite number of doppelgängers, each reading this sentence in a distant universe; a multiverse comprising a vast ocean of bubble universes, of which ours is but one; a multiverse that endlessly cycles through time, or one that might be hovering millimeters away yet remains invisible; another in which every possibility allowed by quantum physics is brought to life. Or, perhaps strangest of all, a multiverse made purely of math.Greene, one of our foremost physicists and science writers, takes us on a captivating exploration of these parallel worlds and reveals how much of reality's true nature may be deeply hidden within them. And, with his unrivaled ability to make the most challenging of material accessible and entertaining, Greene tackles the core questio: How can fundamental science progress if great swaths of reality lie beyond our reach?Sparked by Greene's trademark wit and precision, The Hidden Reality is at once a far-reaching survey of cutting-edge physics and a remarkable journey to the very edge of reality -a journey grounded firmly in science and limited only by our imagination.From the Hardcover edition.