"Time Machines explores the history of time travel in fiction; the fundamental scientific concepts of time, spacetime, and the fourth dimension; the speculations of Einstein, Richard Feynman, Kurt Godel, and others; scientific hypotheses about the direction of time, reversed time, and multidimensional time; time-travel paradoxes, and much more." "Time Machines is highly readable even for those with no physics background. The text contains no equations or higher calculus: All the mathematics are contained in appendices that require nothing beyond differential and integral calculus. Time Machines contains the most extensive bibliography available on the fictional and scientific literature of time travel."--BOOK JACKET.