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 The Allure of the Multiverse, 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.

Shermer and Halpern discuss: definitions of universe and types of multiverses • Is the multiverse science, metaphysics, or faith? • theists claim the "multiverse" is just handwaving around the God answer • many worlds interpretation of quantum mechanics? • inflationary and Darwinian cosmology • infinity and eternity • multiple dimensions • string theory • cyclical universes • Big Bounce • Anthropic Principle (weak, strong, participatory) • time travel • sliding doors, contingency, and the multiverse.

Dr. Paul Halpern is the author of 18 popular science books, exploring the subjects of space, time, higher dimensions, dark energy, dark matter, exoplanets, particle physics, and cosmology. The recipient of a Guggenheim Fellowship, a Fulbright Scholarship, and an Athenaeum Literary Award, he has contributed to Nature, Physics Today, Aeon, NOVA's "The Nature of Reality" physics blog, and Forbes "Starts with a Bang!" He has appeared on numerous radio and television shows including "Future Quest," "Science Friday," "Radio Times," "Coast to Coast AM," "The Simpsons 20thAnniversary Special," and C-SPAN's "BookTV." He appeared previously on the show for his book Synchronicity: The Epic Quest to Understand the Quantum Nature of Cause and Effect. His new book, The Allure of the Multiverse, describes the controversial history of higher dimensional and parallel universe schemes in science and culture.