We commonly think of science fiction as dealing with the future, but there is a fascinating subset of science fiction that looks at the past. Learn how science fiction writers often mix real-life history with fiction and invoke mechanisms such as time travel to explore alternate histories - looking at how the world might have been different had history gone another direction at pivotal points in our past. One illuminating example of this approach, Philip K. Dick's The Man in the High Castle, was recently turned into a series by Amazon.