What is life? Where do its boundaries begin, and where do they end? These are some of the simple yet daunting questions science writer Carl Zimmer explores in his new book, Life’s Edge: The Search for What It Means to Be Alive. From the coronavirus to consciousness, Zimmer seeks to demonstrate that biology, for all its advances, has yet to achieve its greatest possible triumph: a full theory of life. Join this conversation to understand why one of life’s greatest mysteries remains the definition of life itself.