Two experts in the field of nanotechnology, K. Eric Drexler, Ph.D., cofounder of the Foresight Institute in Palo Alto, Calif., and the person who coined the term "nanotechnology," and Richard E. Smalley, Ph.D., a professor at Rice University and winner of the 1996 Nobel Prize in Chemistry, exchanged open letters about this question. These letters are making the -- long -- cover story of the current issue of Chemical & Engineering News.
Drexler predicted a long time ago that these "molecular assemblers" -- devices capable of positioning atoms and molecules for precisely defined reactions in almost any environment -- are not only possible, but will have a huge impact.
They would be able to build anything with absolute precision and no pollution. They would confer something approaching immortality. They would enable the colonization of the solar system.
Like Drexler, Smalley believes the potential of nanotechnology to benefit humanity is almost limitless. But Smalley has a dramatically different conception of nanotechnology from Drexler, one that doesn't include the concept of molecular assemblers. Smalley does not think molecular assemblers as envisioned by Drexler are physically possible.
In lectures and in a September 2001 article in Scientific American, Smalley outlined his scientific objections to the idea of molecular assemblers, specifically what he called the "fat fingers problem" and the "sticky fingers problem."
In this rich exchange, you'll find a letter from Drexler to Smalley asking him to clarify what he meant by "sticky fingers." Smalley answers, Drexler fights back and Smalley concludes. At the end, they still disagree about the issue.
Here are some forceful quotes.
[Drexler in his open letter] A scientist whose research I respect has observed that "when a scientist says something is possible, they're probably underestimating how long it will take. But if they say it's impossible, they're probably wrong." The scientist quoted is, of course, Richard Smalley.
[Smalley in his reply] The central problem I see with the nanobot self-assembler then is primarily chemistry. If the nanobot is restricted to be a water-based life-form, since this is the only way its molecular assembly tools will work, then there is a long list of vulnerabilities and limitations to what it can do. If it is a non-water-based life-form, then there is a vast area of chemistry that has eluded us for centuries.
[Smalley in his conclusion] You don't get it. You are still in a pretend world where atoms go where you want because your computer program directs them to go there. You assume there is a way a robotic manipulator arm can do that in a vacuum, and somehow we will work out a way to have this whole thing actually be able to make another copy of itself. I have given you reasons why such an assembler cannot be built, and will not operate, using the principles you suggest. I consider that your failure to provide a working strategy indicates that you implicitly concur -- even as you explicitly deny -- that the idea cannot work.
If two experts of this stature disagree on such a fundamental question, who is right? Don't count on me to give an answer.
Source: Rudy Baum (introduction), K. Eric Drexler and Richard E. Smalley (letters), Chemical & Engineering News, Volume 81, Number 48, December 1, 2003
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