Jim Holt is a rarity: a writer who throws light on some of the most daunting problems in physics, philosophy and math in ways that are impressively knowledgeable, artful and entertaining. He's outdone himself in his latest book, "Why Does the World Exist: An Existential Detective Story," which confronts the enigma of existence itself, considered from the perspectives of physics, metaphysics and theology. As Kathryn Schulz wrote in the New York Times, "the book is deep, absorbing, associative, challenging, and makes you laugh, unexpectedly and a lot" – much like my experience talking to Jim in this interview.