Science fiction and fantasy tend to be grouped together. Whether listed as “sci-fi/fantasy” by sellers or called “speculative fiction” by enthusiasts, the assumption is that they are the same kind of story. And, in a significant way, they are. Both bring us to worlds other than our own, filled with strange creatures and things that defy the laws of physics we live under.
But they take different roads to reach that end, and the worlds of science fiction and the worlds of fantasy are governed by different dynamics. Science fiction strives to be, well, scientific. The reigning idea of the genre is that everything, no matter how incredible, is completely natural, entirely explicable by the scientific process. Authors often incorporate scientific facts – or at least scientific theories – into their stories. Real phenomena like black holes, solar flares, the different atmospheres of other planets, etc. are dealt with frequently and even factually.
Of course, the science in such books is often purely theoretical, and sometimes impossible. The experts have told us that even traveling faster than the speed of light is impossible. When sci-fi writers cannot be scientific, they try to sound scientific. They explain their impossibilities with psuedo-scientific jargon, making a pretense of obedience to the laws of nature.
Fantasy makes no such pretense, no attempt to explain itself. The Fairyland lives under its own laws, and you don’t have to explain magic. No one wonders how Jack’s beanstalk, however tall, could reach a giant world. No one asks to know the process by which the fairy godmother turns the pumpkin into a coach. But then, no one asks why Cinderella must be back by midnight. The power of love’s first kiss is unquestionable in Faerie, and the doom of touching the needle of the commonest spindle is incontrovertible. The art of fantasy is to create wild freedoms that bring with them peculiar limitations.