If you’ve ever wondered, as Heidegger, put it, “why is there something rather than nothing?” try imagining nothing. That inconceivable void is the point of departure for Jim Holt’s thorough parsing of the question, Why Does the World Exist? (Liveright,$16.95). Holt, author of Stop Me If You’ve Heard This: A History and Philosophy of Jokes, is a genial and thoughtful guide to the many theories we’ve come up with to explain the universe, from creation myths and a benign deity to godless materialist theories and on to the wild, everything-goes scenarios of the multi-verse. For each line of inquiry, Holt surveys the major literature and interviews the experts, pointing out the strengths and weaknesses of each argument. So why is there something? Ultimately, the answers don’t resolve the matter but raise more questions, implicitly suggesting, perhaps, that the world exists to make us wonder.