Every short story in this wonderfully varied collection has one thing in common: each features some alteration in history, some divergence from historical reality, which results in a world very different from the one we know today. As well as original stories specially commissioned from bestselling writers such as James Morrow, Stephen Baxter and Ken MacLeod, there are genre classics such as Kim Stanley Robinson's story of how World War II atomic bomber the Enola Gay, having crashed on a training flight, is replaced by the Lucky Strike with profoundly different consequences. Praise for the editors: 'Mr Watson wreaks havoc with what is accepted - and acceptable.' The Times 'One of Britain's consistently finest science fiction writers.' New Scientist

Every short story in this wonderfully varied collection has in common some diversion in history, some alternate reality from what we know, resulting in a very different world. In addition to original stories specially commissioned from bestselling writers such as James Morrow, Stephen Baxter, and Ken MacLeod, there are genre classics from Kim Stanley Robinson, Harry Turtledove, and George Zebrowski: over 20 stories in all.

Here are 25 stories of science fiction that push the envelope, by the biggest names in an emerging new crop of high-tech futuristic SF - including Charles Stross, Robert Reed, Alastair Reynolds, Peter Hamilton and Neal Asher. High-tech SF has made a significant comeback in the last decade, as bestselling authors successfully blend the super-science of 'hard science fiction' with real characters in an understandable scenario. It is perhaps a reflection of how technologically controlled our world is that readers increasingly look for science fiction that considers the fates of mankind as a result of increasing scientific domination. This anthology brings together the most extreme examples of the new high-tech, far-future science fiction, pushing the limits way beyond normal boundaries. The stories include: "A Perpetual War Fought Within a Cosmic String", "A Weapon That Could Destroy the Universe", "A Machine That Detects Alternate Worlds and Creates a Choice of Christs", "An Immortal Dead Man Sent To The End of the Universe", "Murder in Virtual Reality", "A Spaceship So Large That There is An Entire Planetary System Within It", and "An Analytical Engine At The End of Time", and "Encountering the Untouchable."

Dieselpunk: an emerging retro-futuristic sub-genre, similar to steampunk, based on the era between the First World War and the start of the Atomic Age, merging elements of noir, pulp, and the past with today’s technology . . . and sometimes a dash of the occult. Award-winning editor Wallace presents a cutting-edge collection of twenty-five vibrant stories that explore the possibilities of history while sweeping readers into high-powered hydrocarbon-fuelled adventures. Join us in an era when engines were huge, fuel was cheap and plentiful, and steel and chrome blended with the grit and grease of modern machines. Praise for The Mammoth Book of Steampunk: 'World Fantasy Award-winning editor Wallace has compiled an outstanding anthology . . . sure to satisfy even the most jaded steampunk fans and engage newcomers and skeptics. Each story exemplifies steampunk’s knack for critiquing both the past and the present, in a superb anthology that demands rereading.' Publishers Weekly

An anthology focusing on newer elements of steampunk, one which deconstructs the staples of the genre and expands on them, rather than simply repeating them, with a greater spread both in terms of location and character. This is steampunk with a modern, post-colonial sensibility. Contributors include: Jeff VanderMeer, Caitlín Kiernan, Mary Robinette Kowal, Jay Lake, Cherie Priest, Cat Rambo, Catherynne M. Valente, Genevieve Valentine and many more.

This thought-provoking collection not only takes us into the past and the future, but also explores what might happen if we attempt to manipulate time to our own advantage. These stories show what happen once you start to meddle with time and the paradoxes that might arise. It also raises questions about whether we understand time, and how we perceive it. Once we move outside the present day, can we ever return or do we move into an alternate world? What happens if our meddling with Nature leads to time flowing backwards, or slowing down or stopping all together? Or if we get trapped in a constant loop from which we can never escape. Is the past and future immutable or will we ever be able to escape the inevitable? These are just some of the questions that are raised in these challenging, exciting and sometimes amusing stories by Kage Baker, Simon Clark, Fritz Leiber, Christopher Priest, Kristine Kathryn Rusch, Robert Silverberg, Michael Swanwick, John Varley and many others.

Leading historians suggest what might have been if key events during World War II had the war gone differently.