In reading H.G. Wells’ classic The Time Machine , we keep its subject and all other whirring, light-flashing, time-travel devices safely in the realm of fiction. But for decades theoretical physicists, astrophysicists and philosophers have delved into the reality of time travel, the how of travelling through time. Kip Thorne, Carl Sagan and Steven Hawking are among the new time travellers who, calling on special and general relativity and quantum mechanics, have designed theoretical bases for a variety of time machines.David Toomey brings these brilliant minds to life as they confront temporal paradoxes and questions of free will, probe black holes and time warps, conceive of parallel universes, and imagine a civilisation with the power to send signals into the past. In so doing, Toomey takes the reader on a mind-bending adventure to the very edge of physics.