Rice University Professor Richard Smalley has responded to a longstanding challenge by Dr. Eric Drexler to defend a controversial direction of U.S. nanotechnology policy that excludes molecular assembly. Their four-part exchange, sponsored by the American Chemical Society, is this week’s Chemical & Engineering News cover story.

The controversy centers on “a fundamental question that will dramatically affect the future development of this field,” says Deputy Editor-in-Chief Rudy Baum.

Drexler, Chairman of the Foresight Institute, authored the books that defined the original goals for nanotechnology. He fears that national policy — which currently rejects those goals — is hampering dialogue, increasing security risks, and failing to deliver on revolutionary expectations. Smalley, a specialist in carbon nanotubes and the leading advocate of national efforts in nanoscale science and technology, has been the most vocal detractor of the original goals.

Feynman’s dream betrayed?

Feynman proposed that mechanical systems (now termed molecular assemblers) could direct chemical reactions, building revolutionary, atomically precise products. This vision of nanotechnology helped launch the current global surge in research and spending, including the multi-billion dollar U.S. National Nanotechnology Initiative (NNI).

However, as Baum points out, “Smalley has a dramatically different conception of nanotechnology from Drexler, one that doesn’t include the concept of molecular assemblers.” In a 2001 Scientific American article, Smalley claimed to prove the impossibility of molecular assemblers — a claim used to defend the U.S. NNI leadership’s rejection of the goal. Smalley argued that molecular assembly requires tools that will forever be impossible: “‘There’s plenty of room at the bottom’,” he wrote, “But there’s not that much room,” because “To put every atom in its place … would require magic fingers.”

In the current C&E News exchange, Smalley now agrees that assemblers (without impossible “magic fingers”) could use something like enzymes or ribosomes as tools for doing precise chemistry, but that molecular manufacturing will forever be severely limited — alleging that it must use tools that closely resemble enzymes, and that enzymes can work solely in water, making only materials like “the meat and bone of biology.”

According to Drexler, “Besides misrepresenting molecular manufacturing, these assertions reveal an understanding of enzymatic chemistry that is 19 years out of date: Scientific experiments since 1984 (A. Klibanov, MIT) have proven that many enzymes function effectively in non-aqueous environments. Smalley’s alleged limits on molecular manufacturing clearly do not apply.”

Ralph Merkle, nanotechnology pioneer and Distinguished Professor of Computing at the Georgia Institute of Technology, identifies additional failings: “Smalley hasn’t acknowledged the extensive scientific and technical literature on mechanosynthesis — a literature which includes designs for molecular tools, ab initio quantum chemistry calculations of specific tool-surface interactions, and implementation strategies. My research colleagues and I have published many papers in this new and exciting area, and this work sharply contradicts Smalley’s sweeping dismissal of the field.

“For example, a carbon-deposition reaction which a colleague and I studied using standard quantum chemistry methods moves a carbene tool along a barrier-free path to insert a reactive carbon atom into a dimer on a diamond (100) surface. The tool is then twisted 90 degrees, breaking an internal pi bond, and pulled away to break the remaining sigma bond, leaving a single carbon atom bonded to the dimer on the surface. Further computational chemistry research into fundamental mechanosynthetic reactions should be an integral component of any national nanotechnology program. Smalley’s metaphors merely cloud the issues.”

“Scaring our children”

Baum further observes, “Smalley’s objections to molecular assemblers go beyond the scientific. He believes that speculation about the potential dangers of nanotechnology threatens public support for it.” Smalley also points to scenarios that he says have “scared our children.”

Smalley offers “vehement opinions and colorful metaphors but no relevant, defensible scientific arguments, hence no basis for crucial policy,” responds Drexler. “Smalley has struggled for years to dispel public concerns by issuing false denials of the capabilities of advanced nanotechnologies. That campaign has failed. It should be abandoned.”

Commenting on Smalley’s position, Ray Kurzweil states, “Denying the feasibility of both the promise and the peril of molecular assembly will ultimately backfire, and will also fail to guide research in the constructive direction that is needed.” Kurzweil has also written a detailed analysis of this issue, posted today.

The risks of denial

Regarding U.S. policy, Drexler warns, “In the global race toward advanced nanotechnology, the U.S. NNI leadership has its eyes closed, refusing to see where the race is headed. This creates growing risks of a technological surprise by a strategic adversary, while delaying medical, economic, and environmental benefits. It’s time to remove the blinders and move forward with public dialogue and vigorous research, embracing the opportunities identified by Richard Feynman.”

Last week, the 21st Century Nanotechnology Research and Development Act passed through congress and is awaiting signature from President Bush. The act authorizes $3.7 billion for research and development programs coordinated among several federal agencies. The legislation further provides funding for public hearings, expert advisory panels and established an American Nanotechnology Preparedness Center, which will study nanotechnology’s potential societal and ethical effects.

Drexler believes this Act and the accompanying funds should be applied to long-term research to ensure that the U.S. is not left behind and that our society can enjoy the benefits more quickly. “It is crucial that molecular manufacturing be an integral component of these nationally funded programs,” he says.

The Drexler-Smalley Debate on Molecular Assembly, Ray Kurzweil

More on Smalley-Drexler debate, Foresight Institute

CRN analyzes Drexler-Smalley debate, KurzweilAI.net