http://www.nytimes.com/library/national/science/090500sci-physics-computers. html ][for an article that started the race for quantum computers: http://www.qubit.org/resource/deutsch85.pdf
September 5, 2000 The Ultimate Laptop: A Black Hole By GEORGE JOHNSON
For all the corporate enthusiasm over the unveiling of each new generation of computer chip (last month Intel announced that its Pentium 4 would be packed with 42 million transistors performing as many as 8.4 billion operations per second), consumers may be more apt to feel a sense of dread. Once again the expensive desktop computers and laptops they were so proud of have become outmoded, destined to join the scrap piles of unsalable equipment accumulating in closets everywhere.
Moore's law, which holds that computing power doubles approximately every 18 months, sometimes seems less a blessing than a curse. But the law cannot hold forever, and Dr. Seth Lloyd, an associate professor of mechanical engineering at the Massachusetts Institute of Technology, offers hope that the end is in sight.
In a paper in the current issue of Nature, Dr. Lloyd describes the ultimate laptop -- a computer as powerful as the laws of physics will allow. So energetic is this imaginary machine that using it would be like harnessing a thermonuclear reaction. In the most extreme version of this computer supreme, so much computational circuitry would be packed into so small a space that the whole thing would collapse and form a tiny black hole, an object so dense that not even light can escape its gravity.
If that sounds like a rather dangerous device to hold on one's lap -- "Opening the lid," Dr. Lloyd warns, "voids the warranty" -- there is a serious purpose to his theoretical tour de force: to plumb the absolute limits nature sets on computation.
Nothing like Lloyd's Ultimate Laptop is likely to roll off the assembly line at some future Apple or I.B.M.
But his effort, part of a relatively new discipline called the physics of information, gives computer engineers an ideal to aim for. More importantly, this exercise in extreme computer science may help deepen the understanding of the connections between physics and information, and explore the notion, popular among some theorists, that the very processes of nature can be thought of as computations.
"Work like this exemplifies a fruitful new convergence of theoretical physics, computer science and mathematics," said Gregory Chaitin, a researcher at the I.B.M.
Thomas J. Watson Research Center in Yorktown Heights, N.Y., whose specialties include the mathematics of information.
"Interdisciplinary research of this kind would have been unthinkable a few years ago."
Named for its inventor, Gordon Moore, a founder of Intel, Moore's law has continued to hold true because of the dexterity with which engineers have been able to inscribe smaller and smaller circuitry onto silicon computer chips. As the components of the circuits are squeezed closer together, they can exchange information at faster speeds.
"People have been predicting the demise of Moore's law pretty much since it was posited in the early 60's because some manufacturing technology was about to run out," Dr. Lloyd said. "But Moore's law is a law of human ingenuity rather than of nature. Predictions of its demise have been wrong because people are ingenious."
The vanishingly tiny components on a chip are like switches that can be in two positions, either on or off -- representing a bit of information, 1 or 0. Minuscule as they seem, each of these devices is typically made of about a billion atoms. But laboratories are already experimenting with computers in which a bit is stored by a single atom that can spin clockwise for 1 or counterclockwise for 0. And who is to say that the grain could not someday be even finer with subatomic particles like quarks or gluons or even the hypothetical superstrings harnessed to encode and manipulate information?
But ultimately the limits of nature must prevail. "If we believe the laws of physics," Dr. Lloyd said, "then the fundamental constants of nature should tell us where Moore's law absolutely has to end, where we can't miniaturize any further."