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Preface

In a little time I felt something alive moving on my left leg, which advancing gently forward over my
breast, came almost up to my chin; when bending my eyes downward as much as I could, I perceived
it to be a human creature not six inches high, with a bow and arrow in his hands, and a quiver at his
back. … I had the fortune to break the strings, and wrench out the pegs that fastened my left arm to the
ground; for, by lifting it up to my face, I discovered the methods they had taken to bind me, and at the
same time with a violent pull, which gave me excessive pain, I a little loosened the strings that tied down
my hair on the left side, so that I was just able to turn my head about two inches. … These people are
most excellent mathematicians, and arrived to a great perfection in mechanics by the countenance and
encouragement of the emperor, who is a renowned patron of learning. This prince has several machines
fixed on wheels, for the carriage of trees and other great weights.

(From Gulliver’s Travels—A Voyage to Lilliput, by Jonathan Swift, 1726.)

In the Nevada desert, an experiment has gone horribly wrong. A cloud of nanoparticles — micro-robots —
has escaped from the laboratory. This cloud is self-sustaining and self-reproducing. It is intelligent and
learns from experience. For all practical purposes, it is alive.
It has been programmed as a predator. It is evolving swiftly, becoming more deadly with each passing
hour.
Every attempt to destroy it has failed.
And we are the prey.

(From Michael Crichton’s techno-thriller Prey, HarperCollins Publishers, 2002.)

Almost three centuries apart, the imaginative novelists quoted above contemplated the astonishing, at
times frightening possibilities of living beings much bigger or much smaller than us. In 1959, the physi-
cist Richard Feynman envisioned the fabrication of machines much smaller than their makers. The length
0
scale of man, at slightly more than 10 m, amazingly fits right in the middle of the smallest subatomic par-
ticle, which is approximately 10 26 m, and the extent of the observable universe, which is of the order of
26
10 m. Toolmaking has always differentiated our species from all others on Earth. Close to 400,000 years
ago, archaic Homo sapiens carved aerodynamically correct wooden spears. Man builds things consistent
with his size, typically in the range of two orders of magnitude larger or smaller than himself. But humans
have always striven to explore, build, and control the extremes of length and time scales. In the voyages
to Lilliput and Brobdingnag in Gulliver’s Travels, Jonathan Swift speculates on the remarkable possibili-
ties which diminution or magnification of physical dimensions provides. The Great Pyramid of Khufu
was originally 147 m high when completed around 2600 B.C., while the Empire State Building con-
structed in 1931 is presently 449m high. At the other end of the spectrum of manmade artifacts, a dime
is slightly less than 2 cm in diameter. Watchmakers have practiced the art of miniaturization since the
13th century. The invention of the microscope in the 17th century opened the way for direct observation

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