Where some writers create sci-fi worlds to stretch our notions of the possible, Silverberg increasingly limits our options with grim extrapolations of contemporary reality and half-baked shibboleths. Thus, a grad student who discovers, suddenly, that industrial society is increasingly geared to morons joins an underground proeugenics organization. . . a story about the mid-air destruction of a space liner defends the morality of triage. . . and an extended United Nations debate over whether to ""terraform"" Mars or genetically alter mankind to fit it for life on other planets fizzles out into a short-term political compromise. The slick sociology, interspersed with short shorts demonstrating the author's mechanical ingenuity and/or ""poetic"" whimsicality, makes up a familiar, professionally performed repertoire, but Silverberg's pessimism is often hard to distinguish from plain fatigue.