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, debate a fundamental question of nanotechnology: Are "molecular assemblers" -- devices capable of positioning atoms and molecules for precisely defined reactions in almost any environment -- physically possible?
The debate started after Drexler posted an open letter to Smalley earlier this year on the Foresight Institute Web site challenging Smalley to clarify his arguments against molecular assemblers. That letter was reprinted by C&EN in its current issue, along with three subsequent and exclusive exchanges between the two scientists.
In the letter that sparked the debate, Drexler wrote to Smalley, "I have written this open letter to correct your public misrepresentation of my work." Drexler specifically noted that Smalley had described molecular assemblers "as having multiple 'fingers' that manipulate individual atoms and suffer from so-called fat finger and sticky finger problems." Drexler maintains that, "like enzymes and ribosomes, proposed assemblers neither have nor need these 'Smalley fingers.'"
"My proposal is, and always has been," Drexler continues, "to guide the chemical synthesis of complex structures by mechanically positioning reactive molecules, not by manipulating individual atoms."
In his response, Smalley praised Drexler's pioneering work and his "contributions to the advancement of technology on the nanometer scale." However, he did not concede his viewpoint that molecular assemblers are physically impossible, at least as described by Drexler. Rather, he challenged Drexler to explain how they would work: "So if the assembler doesn't use fingers, what does it use?"
Smalley focused the balance of his response on the chemistry aspect of the assemblers and put forth a series of questions to Drexler. At one point, he even speculated rather tongue in cheek that perhaps Drexler had discovered "a vast area of chemistry that has eluded us for centuries."
Another area of contention between the two scientists concerns the potential undesirable consequences of nanotechnology. Drexler, who has touted nanotechnology's amazing potential, also warned of its possibly negative effects in his 1986 book, Engines of Creation: The Coming Era of Nanotechnology. In his initial letter, Drexler wrote that Smalley apparently fears "that my warnings of long-term dangers will hinder funding of current research."
In response, Smalley related the concerns he heard recently from high school and middle school students, who were worried what would happen if so-called self-replicating "nanobots" started to spread around the world. "You and people around you have scared our children," Smalley wrote. "I hope others in the chemical community will join me in turning on the light, and showing our children that, while our future in the real world will be challenging and there are real risks, there will be no such monster as the self-replicating mechanical nanobot of your dreams."
Drexler began his nanotechnology work as a research affiliate at the Massachusetts Institute of Technology, where he earned his Ph.D. in 1991. He is the chairman of the board of directors of the Foresight Institute.
Smalley, who won the Nobel Prize for the discovery of fullerenes, a molecular form of pure carbon, is a University Professor and professor of chemistry, physics and astronomy at Rice. He is an advocate for coordinated national research on nanotechnology, according to C&EN.
EDITOR'S NOTE: The full exchange of letters between Drexler and Smalley is available online to reporters at http://pubs.