Science fiction is a genre of fiction. It differs from fantasy in that, within the context of the story, its imaginary elements are largely possible within scientifically established or scientifically postulated laws of nature (though some elements in a story might still be pure imaginative speculation). Exploring the consequences of such differences is the traditional purpose of science fiction, making it a "literature of ideas". Science fiction is largely based on writing rationally about alternative possibilities. The settings for science fiction are often contrary to known reality.
The study of science fiction, or science fiction studies, is the critical assessment, interpretation, and discussion of science fiction literature, film, new media, fandom, and fan fiction. Science fiction scholars take science fiction as an object of study in order to better understand it and its relationship to science, technology, politics, and culture-at-large.
The field has grown considerably since the 1970s with the establishment of more journals, organizations, and conferences with ties to the science fiction scholarship community, and science fiction degree-granting programs such as those offered by the University of Liverpool and Kansas University.
A controversial part of the book depicts humans, in the far-off future, escaping the dying Earth and settling on Venus — in the process totally exterminating its native inhabitants, an intelligent marine species. Stapledon's book has been interpreted by some as condoning such interplanetary genocide as a justified act if necessary for racial survival, though a number of Stapledon's partisans denied that such was his intention, arguing instead that Stapledon was merely showing that although mankind had advanced in a number of ways in the future, at bottom it still possessed the same capacity for savagery as it has always had.