He argues that quantum computation, a discipline in which he is a pioneering thinker, has the potential for building computers that draw on their counterparts in parallel universes; this could make artificial intelligence a reality, despite Roger Penrose's objections (which Deutsch deals with in some detail). Likewise, time travel into both the future and the past should be possible, though not in quite the form envisioned by science fiction writers; the trips would almost certainly be one-way, and they would likely take the travelers into different universes from the one they began in.

Deutsch takes particular pains to refute Thomas Kuhn's "paradigm" model of science, which essentially denies progress. A final chapter looks at the long-range implications of his views, including the place of esthetic and moral values (areas more scientists now seem willing to confront).

Not easy going by any means, but worth the work for anyone interested in the thought processes of a scientist on the leading edge of his discipline.

For scientists and lay readers alike, this complete and rational synthesis of disciplines offers a new, optimistic message about existence. Deutsch discusses, demystifies and connects such topics as quantum computers; the physics of time travel; the comprehensibility of nature and the physical limits of virtual reality; the significance of human life; and the ultimate fate of the universe. Charts & figures throughout.

"Deutsch presents his vision of reality by combining ideas from four "strands" of science: quantum physics, epistemology, the theory of computation, and modern evolutionary theory. The implications of Richard Dawkins' work is also discussed in the book. I highly recommend it." -- John Catalano