It is always cheering to clear up a troublesome literary and scientific mystery. Isaac Asimov's long-running chronicles of our future have posed one such problem, and now in his seventieth year the answer can at last be revealed, thanks to analysis based on computer hardware specifications.
In its early days the difficulty wasn't recognised. Asimov appeared to be recording two incompatible histories of things to come. One ran from the near future to a time when human colonies are established in several distant solar systems, and revolved around the uses and abuses of intelligent humanoid robots (I, Robot, 1950, and sequels). The second covered a much later period of galaxy-wide hegemony, and was characterised by a total absence of any robots or artificial intelligences whatever (the Foundation trilogy, 1951-53).
Students tended to assume either that these future histories occurred on alternate time-lines--a conjecture easily sliced apart with Occam's Razor--or that one, very probably the first, was fictional.
Dr Asimov dropped his bombshell with the book Foundation's Edge (1982), in which the two historical sequences were declared to be one. Several more dismayingly bulky volumes have expanded on...