Ringworld is one of several works dealing with carefully worked out alien worlds, including Poul Anderson's The Man Who Counts (1958) (also published as War of the Wing Men) and Hal Clements's Mission of Gravity (1955). The art of world-building, of designing a fictional planet from geography down to its inhabitants' recreations, is one of the highest accomplishments of hard science fiction. The ability to take a concept like the Ringworld and work out the problems of gravity, atmosphere, and lighting requires great skill at extrapolation, of making logical deductions on the basis of a few givens. This is an essential part of science fiction, its ability to cause the reader to imagine other worlds. Science fiction can tap into people's desire to escape into realms that might be reached by new forms of technology. Much of science fiction's popularity springs from such a desire.