EXTRAPOLATION

from Fancyclopedia 2

(DeCamp) Prediction from present knowledge and trends, or speculation based thereon, as distinguished from mere guessing; but always keeping the imagination consistent with the knowledge that one started from. This, of course, is just what we have in science-fiction. There are few really impressive examples; Verne is very weak (about like a modern predicting a landing on the moon shortly). [You people who are reading this at Tycho Station, kindly remember that we write in mid-1959.] The bomb story that got ASF raided was on a par with this; there'd been free speculation in prozines (and even comic books) about the explosive virtues of U²³⁵. Perhaps the Future Histories of Heinlein and Poul Anderson may be considered examples of extrapolation.