[1][2][3] The term was first used in print in 1957 by P. Schuyler Miller in a review of John W. Campbell's Islands of Space in the November issue of Astounding Science Fiction.
Though there are examples generally considered as "hard" science fiction such as Isaac Asimov's Foundation series, built on mathematical sociology,[7] science fiction critic Gary Westfahl argues that while neither term is part of a rigorous taxonomy, they are approximate ways of characterizing stories that reviewers and commentators have found useful.
[16] One requirement for hard SF is procedural or intentional: a story should try to be accurate, logical, credible and rigorous in its use of current scientific and technical knowledge about which technology, phenomena, scenarios and situations that are practically or theoretically possible.
[18] Hard science fiction authors only include more controversial devices when the ideas draw from well-known scientific and mathematical principles.
For example, a group at MIT concluded that the planet Mesklin in Hal Clement's 1953 novel Mission of Gravity would have had a sharp edge at the equator, and a Florida high school class calculated that in Larry Niven's 1970 novel Ringworld the topsoil would have slid into the seas in a few thousand years.