K. Eric Drexler

If you take all the factories in the world today, they could make all the parts necessary to build more factories like themselves. So, in a sense, we have a self-replicating industrial system today, but it would take a tremendous effort to copy what we already have.

My greatest concern is that the emergence of this technology without the appropriate public attention and international controls could lead to an unstable arms race.

On the molecular scale, you find it's reasonable to have a machine that does a million steps per second, a mechanical system that works at computer speeds.

An international race in the relevant technologies is getting under way at this point, not necessarily with an understanding of where that race leads in the long run, but strongly motivated by the short-term payoffs.

The basic parts, the start-up molecules, can be supplied in abundance and don't have to be made by some elaborate process. That immediately makes things simpler.

But while doing that I'd been following a variety of fields in science and technology, including the work in molecular biology, genetic engineering, and so forth.

The really big difference is that what you make with a molecular machine can be completely precise, down to the tiniest degree of detail that can exist in the world.