A salon with celebrated inventors of alternative futures. Science fiction is really a look at human history, society, and even human nature.  Three authors of popular science fiction spar over exactly how science fiction is constrained by known science and then question the value of science fiction.  The authors describe the way in which science fiction can inspire scientific research and at the same time serve as a warning against our potential misuse of the awesome power of science (citing the novels Soylent Green and On the Beach).  They also good-naturedly point out its limitations – e.g., no science fiction author predicted the personal computer—and wonder why its appeal is not as strong in some countries as in others. With David Brin, Octavia E. Butler, Michael Crichton.