Amazon.com (ISBN 0195120426, Hardcover)

The thought that humans might one day be able to harness time, traveling freely from one age to another, has been a fixture of science fiction for years. Science fact is beginning to catch up to the long-held dream: in this entertaining survey, researcher-writer Clifford Pickover observes that current theories of physics support--or at least do not rule out--the possibilities of time travel.

In chapters that mix whimsical science-fiction scenarios with brief essays on matters of fact, Pickover takes a leisurely stroll through various chrono-cosmological theories and discusses their attendant virtues, flaws, and inherent paradoxes. One modern notion, Kurt Gödel's addendum to Albert Einstein's general theory of relativity, posits a rotating universe in which it is possible for a traveler to move between states of time and return to the present (assuming, of course, that there is such a thing as the present); the theory depends on a universe that rotates slowly, which seems not to be the case, but, as Pickover points out, it nevertheless provides a mathematical basis for time travel--which, he suggests, is a fine and worthy start. Pickover peppers his well-illustrated text with learned asides on such matters as light-cone diagrams, rocket clocks, string theory, parallel universes, and other topics real and speculative. What he turns up in the course of his narrative is fascinating--and fuel for anyone who entertains dreams of interdimensional wandering. --Gregory McNamee