Meanwhile, nanotechniques are already being used to make sunscreens, stain-resistant fabrics, and composite materials in cars. Soon they will be used to make computers and storage devices of extremely small size.

And some of the long-anticipated "miracle" products have started to appear as well. In 2002 one company was manufacturing self-cleaning window glass; another made a nanocrystal wound dressing with antibiotic and anti-inflammatory properties. At the moment nanotechnology is primarily a materials technology, but its potential goes far beyond that. For decades there has been speculation about self-reproducing machines. In 1980 a NASA paper discussed several methods by which such machines could be made. Ten years ago, two knowledgeable scientists took the matter seriously:

Within fifty to a hundred years, a new class of organisms is likely to emerge. These organisms will be artificial in the sense that they will originally be designed by humans. However, they will reproduce, and will "evolve" into something other than their original form; they will be "alive" under any reasonable definition of the word… The pace of evolutionary change will be extremely rapid… The impact on humanity and the biosphere could be enormous, larger than the industrial revolution, nuclear weapons, or environmental pollution. We must take steps now to shape the emergence of artificial organisms…

And the chief proponent of nanotechnology, K. Eric Drexler, expressed related concerns:

There are many people, including myself, who are quite queasy about the consequences of this technology for the future. We are talking about changing so many things that the risk of society handling it poorly through lack of preparation is very large.

Even by the most optimistic (or dire) predictions, such organisms are probably decades into our future. We may hope that by the time they emerge, we will have settled upon international controls for self-reproducing technologies. We can expect such controls to be stringently enforced; already we have learned to treat computer virus-makers with a severity unthinkable twenty years ago. We've learned to put hackers in jail. Errant biotechnologists will soon join them.