A significant tradition in Science Fiction has focused on speculation regarding future technologies and thought experiments concerning human progress and alien civilisation, often predicated on real physics: ‘hard’ Science Fiction. 

However, there has always been a looser and more story-based side to the genre, in which scientific plausibility matters less than adventure, wonder, social speculation or mythic possibility. At its furthest edge, Science Fiction can blur into Science Fantasy, where the line between technology and magic becomes uncertain. In contemporary media, these tendencies find contrasting expression in the more scientifically rationalised universe of Star Trek and the more mythopoeic world of Star Wars.