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.
Star Maker is an influential science fiction novel by Olaf Stapledon, written in 1937. Stapledon undertakes the immense task of describing the entire history of life in the universe. It dwarfs in scale even his 1930 book Last and First Men, which is a history of the human species over two billion years. It tackles philosophical themes such as the essence of life, of birth, decay and death, and the relationship between creation and creator. The narrator starts with a concern at the clash of ideas on Earth and finds analogies to both communism and fascism among the aliens he visits.
A pervading theme is that of progressive unity within and between different civilizations. Some of the elements and themes briefly discussed prefigure later fiction concerning genetic engineering and alien life forms. Arthur C. Clarke considered Star Maker to be one of the finest works of science fiction ever written.