Time travel makes great science fiction, but can it really be done? Travel into the future is already a reality, but visiting the past is a much tougher proposition, and may require fantastic resources such as a wormhole in space. Nevertheless, if going back in time is allowed, even in principle, then what about all those paradoxes that make time travel stories so intriguing?
Paul Davies is a physicist, cosmologist and astrobiologist at Arizona State University, where he is Director of the Beyond Center for Fundamental Concepts in Science. He is the author of many books, including “How to Build a Time Machine” and, most recently, “The Eerie Silence: are we alone in the universe?”