Synopsis: This editorial discusses the distinction between "science fiction" and "alternate history" stories. Schmidt's view is that an SF story has to involve a plausible change in our understanding of "the laws of nature or how they play out in the large-scale development of the world". In an alternate history story, instead, the change must involve our understanding of the facts of human history. Schmidt considers that these are independent categories, such that a story can fall into either, neither or both. The editorial ends with a discussion of how the length of a story affects how willing readers are to tolerate a divergence from typical SF story subjects.