By the time we finish this book, we understand a wide variety of scientific concepts pertaining to time. And most important, we will understand that time travel is, indeed, possible.

Like a number of his other books, Surfing is structured as a fiction, in this case an X-Files romance--Pickover clearly has a deep and personal appreciation for Scully (whom he calls "Sally," presumably on advice of counsel). You, dear reader, are the FBI's chief investigator of four-dimensional phenomena. As you and your cohorts chase bizarre manifestations from "upsilon" (4-D up) and "delta" (4-D down), Pickover provides explanations, paradoxes, and problems, with many helpful drawings and computer-generated illustrations.

Pickover's book, like every work on higher dimensions, is something of a sequel to Edwin Abbott's classic story, Flatland. Like Abbott, Pickover doesn't just look at the mathematics: "I want to know if humankind's Gods could exist in the fourth dimension." Not for the theologically squeamish, this book is lively, provocative, outrageous, and fascinating. --Mary Ellen Curtin

Whether or not you believe in life on other planets, the artist's renditions of creatures such as Cheelas, Mesklinites, and Radiates from SF novels, as well as mathematical "alien messages" to decipher, are a real treat. (Here's an easy one: "Aliens are waiting for humanity to replace the question mark with the next value in the sequence before they will consider us worthy for further communication: 77, 49, 36, 18, ?") He also raises interesting issues; for example, what form would art take for creatures sensitive to smells or heat rather than light? To top it off, Pickover includes examples of potential interplanetary humor taboos: "Don't make puns around Scolexes because it outrages their sense of linguistic symmetry, which they've fought holy wars over." SF fans will enjoy this entertaining and thought-provoking book. --C.B. Delaney