JOHN D. BARROW, a physicist, is Professor of Mathematical Science, Director of the Millennium Mathematics Project, University of Cambridge, and Gresham Professor of Geometry.

He is the author of The World Within the World, Pi in the Sky, Theories of Everything, The Origin of the Universe (Science Masters Series),The Left Hand of Creation, The Artful Universe, Impossibility: The Limits of Science and the Science of Limits; Between Inner Space and Outer Space; and The Constants of Nature: From Alpha to Omega—the Numbers That Encode the Deepest Secrets of the Universe:andThe Constants of Nature: From Alpha to Omega.