It has been 20 years since the futurist Eric Drexler daringly predicted a new world where miniaturized robots would build things one molecule at a time. The world of nanotechnology that Drexler envisioned is beginning to come to pass, with scientists conjuring new applications daily.

Now Salvatore Torquato, a Princeton University scientist, is proposing turning a central concept of nanotechnology on its head. If the theory bears out -- and it is in its infancy -- it could have radical implications not just for industries like telecommunications and computers but also for our understanding of the nature of life.

Torquato and colleagues have published a paper in the November 25, 2005 issue of Physical Review Letters, the leading physics journal, outlining a mathematical approach that would enable them to produce desired configurations of nanoparticles by manipulating the manner in which the particles interact with one another.

This may not mean much to the man on the street, but to the average scientist it is a fairly astounding proposition.

"In a sense this would allow you to play God, because the method creates, on the computer, new types of particles whose interactions are tuned precisely so as to yield a desired structure," said Pablo Debenedetti, a professor of chemical engineering at Princeton.

The standard approach in nanotechnology is to come up with new chemical structures through trial and error, by letting constituent parts react with one other as they do in nature and then seeing whether the result is useful.

Nanotechnologists rely on something called "self-assembly." Self-assembly refers to the fact that molecular building blocks do not have to be put together in some kind of miniaturized factory-like fashion. Instead, under the right conditions, they will spontaneously arrange themselves into larger, carefully organized structures.

As the researchers point out in their paper, biology offers many extraordinary examples of self-assembly, including the formation of the DNA double helix.

(www.nanotechnology.com)