For the better part of a century, attempts to explain what was really going on in the quantum world seemed doomed to failure. But recent technological advances have made the question both practical and urgent. A brilliantly imaginative group of physicists at Oxford University have risen to the challenge. This is their story. At long last, there is a sensible way to think about quantum mechanics. The new view abolishes the need to believe in randomness, long-range spooky forces, or conscious observers with mysterious powers to collapse cats into a state of life or death. But the new understanding comes at a price: we must accept that we live in a multiverse wherein countless versions of reality unfold side-by-side. The philosophical and personal consequences of this are awe-inspiring. The new interpretation has allowed imaginative physicists to conceive of wonderful new technologies: measuring devices that effectively share information between worlds and computers that can borrow the...