You can find academic and industrial groups doing some relevant work, but there isn't a focus on building complex molecular systems. In that respect, Japan is first, Europe is second, and we're third.

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.

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.

I had been impressed by the fact that biological systems were based on molecular machines and that we were learning to design and build these sorts of things.

Protein engineering is a technology of molecular machines - of molecular machines that are part of replicators - and so it comes from an area that already raises some of the issues that nanotechnology will raise.

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.