Beware the butterfly effect! With stories from Ray Bradbury, George R.R. Martin, Harry Turtledove, here are 16 journeys into the past that might just change everything, forever.

Intrepid chrononauts Ann and Jeff VanderMeer have scoured time itself to bring you this instalment (the second of four) from their über-guide to exploring the fourth dimension, THE TIME TRAVELLER'S ALMANAC. Be warned: reality will be warped, wormholes opened, paradoxes woven and parallel universes breached.

Just as well then that within these pages you'll also find Stan Love's Time Travel in Theory and Practice...