What will the world look like when computers are smarter than their owners? Kurzweil, the brains behind some of today's most brilliant machines, offers his insights. Kurzweil (The Age of Intelligent Machines, not reviewed) posits that technological progress moves at exponential rates. If we apply that standard to the future of computer evolution, another 20 years or so will give us machines with as much memory and intelligence as ourselves. This projection involves a certain faith in as yet unforeseeable technical breakthroughs. There is no obvious way to reduce the size of an electrical circuit beyond a few atoms' width, for example--but the speed of circuits is a function of their size. Kurzweil gets around this limit (known in the computer industry as Moore's Law) by suggesting a relationship between the pace of time and the degree of chaos in a system; as order increases, the interval between meaningful events decreases. In other words, a more highly evolved system will continue to evolve at increasing speed. While this seems more a matter of faith than an inevitable law of nature, the history of technology (as Kurzweil summarizes it) seems to bear out the relationship. He extrapolates the future of computer technology, offering both a detailed time line and imaginary dialogues with a fully intelligent computer from a hundred years in our future. (This sort of imaginative exercise inevitably partakes to some degree of science fiction.) The book's deliberately nonlinear organization offers a variety of paths through the subject matter, as well, and Kurzweil encourages the reader to take whichever approach is attractive. While much of the material (Turing tests, AI research) will be familiar to readers who have followed the growth of computer science, Kurzweil's broad outlook and fresh approach make his optimism hard to resist. Heavy going in spots, but an extremely provocative glimpse of what the next few decades may well hold.