The noted science-fiction writer blurs the boundaries between present and future, fiction and nonfiction, in this collection of three apocryphal essays. ''One Human Minute'' purports to be a review of a book collecting statistics on everything that occurs on Earth in 60 seconds; in fact, it's a meditation on the nature of reality and the meaning of human behavior plus a wickedly funny satire of publishing. ''The Upside-Down Evolution'' chronicles the metamorphosis of 21st century armaments from nuclear stockpiles into micro-armies of ''synsects,'' deadly machines so tiny and elusive that conventional weapons are helpless against them. ''The World As Cataclysm'' pretends to be an introduction to a book of the same title; it sees the emergence of humanity as the end result of a series of catastrophic, chance occurrences that killed off other species with just as good a claim to rule the world. (''The laws of Nature act not in spite of random events but through them,'' he concludes.) Lem's delightful sense of humor accentuates his essential seriousness about humanity's possible fate.