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.
The Invisible Man is a science fictionnovella by H.G. Wells published in 1897. Wells' novel was originally serialised in Pearson's Magazine in 1898, and published as a novel the same year. The Invisible Man of the title is Griffin, a scientist who theorises that if a person's refractive index is changed to exactly that of air and his body does not absorb or reflect light, then he will be invisible. He successfully carries out this procedure on himself, but cannot become visible again, becoming mentally unstable as a result.
Russian writer Yakov I. Perelman pointed out in Physics Can Be Fun (1913) that from a scientific point of view, a man made invisible by Griffin's method should have been blind, since a human eye works by absorbing incoming light, not letting it through completely. However, Wells briefly addresses this in Chapter 20. In the passage describing the experiment on the invisible cat Wells wrote "there remained two little ghosts of her eyes" meaning that its eyes (and retinas presumably) were just visible, and thus able to function by absorbing light.