Is time travel possible? This is a question that has puzzled human thought for centuries. "The answer is certainly affirmative," declares distinguished theoretical physicist Paul Davies.

With scientific precision and innate humor, he continues: "To visit the future, all we need is a little help from gravity and a spaceship that can travel at a speed just below that of light. As for returning to the past, the best way is to find a neighboring black hole equipped with a passage wormhole."

However, time travel is overflowing with "paradoxes," at the heart of which lies the problem of causality: what happened yesterday affects what happens today. The most famous of the time travel paradoxes is the one where the traveler returns to the past and murders his mother.

Exceedingly imaginative and theoretically substantiated, the work Time Machines is "creative science at its best." The book enlightens, entertains, and provokes thought.