Time Machines

An overview of time travel - the mystery of time travel; machineless time travel without dreams or drugs; time travel by machine; H.G. Wells - why his time machine won't work; travelling to the future; on the nature of time, spacetime and the fourth dimension - what is time? speculations on the reality of time; has the past been for ever?; time and clocks; hyperspace and wormholes; the arrows of time - language of time travel; does time have a direction?; cause and effect; what does "now" mean?; irreversibility; time-travel paradoxes and (some of) their explanations - paradoxes; early science fiction speculations on time-travel paradoxes; can the present change the past?; can the past be un-done?; changing vs. affecting the past. Epilogue.