Einstein's theory of general relativity opens the door to other universes, and weird universes at that: universes that allow time travel, universes where you can see the back of your head, universes that spin and bounce or multiply without limit. The Book of Universes gives us a stunning tour of these potential universes, introducing us along the way to the brilliant physicists and mathematicians who first revealed their startling possibilities. John D. Barrow explains the latest discoveries and ideas that physics and astronomy have to offer about our own universe, showing how these findings lead to the concept of the "multiverse"-the Universe of all possible universes. New ideas force us to confront the possibility that our visible universe is a tiny region, governed by its own laws, within a Multiverse containing all the strange universes that could be-an idea that is among the most exciting and revolutionary in all of modern science.