The New Time Travelers

April 30, 2007
According to Toomey, professor of English who teaches technical and nonfiction writing at the University of Massachusetts–Amherst, the concept of time travel successfully made the transition from science fiction to the research literature of physics about 20 years ago. This is not to say that physicists uncritically accept the idea but simply that it is now a topic for rigorous scientific discussion. Because Toomey (Stormchasers) spends as much time describing the personalities of those investigating this odd field as he does the subject's technical aspects, he is able to bring the topic fully to life. The contributions made by Stephen Hawking, Carl Sagan and Kip Thorne, in addition to other lesser-known physicists, are described, but even the author's fine writing is not able to make all of the highly technical material easily understood. Given that time travel, if it can occur at all, is likely to involve wormholes and worldlines, multiverses and Minkowski diagrams, as well as negative energy and naked singularities, this is not surprising. Toomey is at his best treating the many paradoxes that time travel engenders and exploring the ways around them, from Hawking's “chronology protection conjecture” to David Deutsch's creation of multiple universes. While physicists have, to date, been unable to demonstrate that any laws of nature make time travel impossible, Toomey makes it clear that we shouldn't expect to make such a trip any time soon. 15 illus.

July 1, 2007
Kip Thornes Black Holes and Time Warps (1994) remains the best general-audience book about the outr' physics of time travel, butfor lay readers who maywant a less-technical introduction, Toomeys title fills the bill. Itillustrates dimension-bending concepts with space-time diagrams, M. C. Escher drawings, and the plot of H. G. WellsTime Machine. Toomey gets a grip on bending the fourth dimension by historically chronicling physicists who have theorized about time travel, Thorne included. As is so often the case in physics, it all goes back to Einstein. After imparting the basic ideas of relativity, Toomey explains how they led physicists to imagine what would happen to light or matterwhen dragged through strong gravitational fields. He introduces black-hole gurus John Wheeler and Stephen Hawking and, relating the deficiency of black holes as time machines (they offer one-way trips), shifts to theoretically permissible specifications of time travel as conceptualized by pioneers Thorne, Frank Tipler, and Igor Novikov. If you dream of getting outside your personal light cone, Toomey shows how it might be imagined.(Reprinted with permission of Booklist, copyright 2007, American Library Association.)