What if you could change the past?

It's an old dream. As far back as 35 BC Livy, a Roman historian, wondered what would have happened if Alexander the Great had not died young.

Someday it may even be possible to change the past, or at least explore alternate realities. Modern scientists speculate that parallel universes might actually exist. Quantum physicists argue that every time you toss a coin, the universe splits into two copies, heads and tails. Some cosmologists believe our universe is just one of many, stacked up like pages in a book. But even if you could, should you change the past? Chaos theory tells us that large and unexpected consequences can follow from small actions.

Perhaps someday we will be able to access other timelines, for good or ill. Until then, we can only dream – what if?

The essays in this book explore many aspects of alternate history – but it is important to remember that history is determined by more than human choices and achievements.

The Sidewise Award of 2014, given for the best alternate history fiction of the previous year, featured a tie in its long form section. Of the two (deserved) winners, D. J. Taylor's The Windsor Faction (2013) is a subtle alternate history of the early days of the Second World War:

Thanks to the death of Wallis Simpson in 1936 (after complications following surgery for appendicitis), Edward VIII does not abdicate, and as war approaches he is active in trying to avert hostilities: a ‘Windsor Faction’ gathers, a loose collection of right-wing MPs, writers, and others, who argue against going to war. In the end the Nazis’ aggression forces the conflict into being, but a different war from the historical follows.

The second Sidewise winner of 2014 was Bryce Zabel's Surrounded by Enemies (2013), in which Kennedy survives the 1963 assassination attempt: