We have lived for some years with the first of these self-replicating entities, computer viruses. And we are beginning to have some practical experience with the problems of biotechnology. The recent report that modified maize genes now appear in native maize in Mexico-despite laws against it, and efforts to prevent it-is just the start of what we may expect to be a long and difficult journey to control our technology. At the same time, long-standing beliefs about the fundamental safety of biotechnology-views promoted by the great majority of biologists since the 1970s-now appear less secure. The unintended creation of a devastatingly lethal virus by Australian researchers in 2001 has caused many to rethink old assumptions. Clearly we will not be as casual about this technology in the future as we have been in the past. Nanotechnology is the newest of these three technologies, and in some ways the most radical. It is the quest to build man-made machinery of extremely small size, on the order of 100 nanometers, or a hundred billionths of a meter. Such machines would be about 1,000 times smaller than the diameter of a human hair. Pundits predict these tiny machines will provide everything from miniaturized computer components to new cancer treatments to new weapons of war.

As a concept, nanotechnology dates back to a 1959 speech by Richard Feynman called "There's Plenty of Room at the Bottom." Forty years later, the field is still very much in its infancy, despite relentless media hype. Yet practical advances are now being made, and funding has increased dramatically. Major corporations such as IBM, Fujitsu, and Intel are pouring money into research. The U.S. government has spent $1 billion on nanotechnology in the last two years.