David Darling has a Ph.D. in astronomy and has been a full-time freelance science writer for more than twenty years. He is the author of Teleportation: The Impossible Leap, as well as three science encyclopedias: The Universal Book of Mathematics, The Universal Book of Astronomy, and The Complete Book of Spaceflight, all available from Wiley. His other narrative science titles include Deep Time and Equations of Eternity, a New York Times Notable Book. Darling's articles and reviews have appeared in Astronomy, Omni, Penthouse, New Scientist, the New York Times, and the Guardian, among others. He also hosts a major informational Web site, www.daviddarling.info.