Our books, our movies—our imaginations—are obsessed with extra dimensions, alternate timelines, and the sense that all we see might not be all there is. In short, we can’t stop thinking about the multiverse. As it turns out, physicists are similarly captivated.     In , physicist Paul Halpern tells the epic story of how science became besotted with the multiverse, and the controversies that ensued. The questions that brought scientists to this point are big and deep: Is reality such that anything can happen, must happen? How does quantum mechanics “choose” the outcomes of its apparently random processes? And why is the universe habitable? Each question quickly leads to the multiverse. Drawing on centuries of disputation and deep vision, from luminaries like Nietzsche, Einstein, and the creators of the Marvel Cinematic Universe, Halpern reveals the multiplicity of multiverses that scientists have imagined to make sense of our reality. Whether we live in one of many different possible universes, or simply the only one there is, might never be certain. But Halpern shows one thing for sure: how stimulating it can be to try to find out.