Some characteristics of literary science fiction include a future or alternative historical setting and a level of scientific, technological or social plausibility. Other common features include characters such as aliens or robots and futuristic technology, such as teleportation or space travel, though not all science fiction features these elements.
There is no universally accepted definition of literary science fiction, but the genre is typically concerned with realistic speculation about alternative or future worlds and events. Science fiction differs from fantasy literature, which makes no attempt at plausibility. The scientific and technological developments in science fiction literature are often rationally possible given existing technology. Earlier works of science fiction often depicted speculative developments that eventually became reality, such as space travel and video communication.
Science fiction literature may also depict a modern setting that occurs within an alternative historical timeline. For example, Phillip K. Dick's novel, "The Man in the High Castle," depicts a world in which Germany wins World War II. Literary science fiction may also depict settings with radically different social structures. Dystopian literature, for example, depicts a society altered in some negative way. Popular examples of dystopian science fiction include Margaret Atwood's "The Handmaid's Tale" and George Orwell's "1984," both of which depict oppressive, totalitarian governments. Though fictional and speculative, these novels speak to real-world concerns about subjects such as fascism and gender inequality.