The document discusses definitions of science fiction from various science fiction authors and sources. Isaac Asimov defines science fiction as literature concerned with the impact of scientific advance on humans. Ray Bradbury sees science fiction as sociological studies of the future based on extrapolating current trends. John Scalzi outlines three criteria for science fiction: it takes place in the future or what was the future when written, uses technology that did not exist at the time, and events are rationally based. The document also explores the relationship between science fiction and scientific literacy as well as the differences between science fiction and fantasy.