David Deutsch prefers not to travel. He would rather remain in his study, working. And after listening to the 42-year-old Oxford physicist for a moment, you understand his predilection. How horizons-expanding could any trip be to a man who believes that untold numbers of universes coexist with our own, and that many of them contain a David Deutsch, also happily ensconced in his study?
Deutsch’s lack of intimate contact with the world at large does not preclude his ability to change it profoundly. Ten years ago he conceived of a new type of machine--a quantum computer--which at the time seemed unlikely ever to be built. Now a handful of physicists are actually trying to construct the computer Deutsch envisioned, one whose fundamental components are single atoms or even individual particles of light. If someone succeeds--and it must be said that the technological obstacles are formidable--the very existence of such a device, Deutsch believes, will validate his rather unusual view of reality, or as he might say, realities.
A quantum computer would not be merely another step down the well-trodden and seemingly endless road toward ever smaller and more powerful computers. It would in some sense be the ultimate computer, less a machine than a force of nature. Paradoxically, it would take what had appeared to be an unavoidable limitation on computer power imposed by the laws of physics and turn that limitation into a new way of processing information, one that would dwarf the capacities of any existing computer.
A remarkable device, to be sure--but one whose actuality leaves Deutsch unmoved. I really would be hardly interested in this at all if it weren’t for the implications for physics, he says. I’m a theoretical physicist. I want to understand physics fundamentally. It’s not particularly my brief to make better computers.
Nevertheless, Deutsch’s work directly addresses a central problem in computer technology: namely, that components cannot continue to shrink indefinitely. At some point we will be able to squeeze no more circuits onto a chip, and thus wrest no more speed, no more power out of our powerful, speedy machines. At the current rate, we’re going to hit the atomic scale in 20 years’ time, says MIT physicist Seth Lloyd. When that happens, the rules of classical physics that govern the way computers operate will begin to break down and the laws of quantum mechanics will take over.
