Nanobots Tiny Machines Could Be Hugely Efficient—Or Turn Us All Into "Grey Goo"

Here come the nanobots. Although it sounds like something out of the Terminator films, scientists are taking seriously the concept that we could engineer tiny machines to, well, serve man. And hopefully not in the same sense as the 1960s Twilight Zone episode—where the alien volume To Serve Man turned out not to be an exercise in altruism but a cookbook.

As early as 1959, noted genius and scientific authority Dr. Richard Feynman imagined the possibilities of tiny machines accomplishing useful work. In surveying the huge, room-filling computers of the day, he asked in a speech at CalTech, “Why can’t we make them very small, make them of little wires, little elements—and by little, I mean little. For instance, the wires should be 10 or 100 atoms in diameter, and the circuits should be a few thousand angstroms across

“When we get to the very, very small world—say, circuits of seven atoms—we have a lot of new things that would happen…Atoms on a small scale behave like nothing on a large scale, for they satisfy the laws of quantum mechanics.”

The latter-day scientist Dr. K. Eric Drexler, who first wrote of the possibilities of nanosystems in a 1981 paper for the National Academy of Sciences, talks of Feynman’s work as leading the way to a new form of manufacturing. He envisions not self-replicating machines (a potentially scary concept), but tiny factories that make tiny parts “that can be snapped together to make more nanofactories.”

Drexler imagines incredibly efficient “micron-scale computer CPUs’ running on 100 nanowatts that would make possible air-cooled desktops with a billion individual processors. Surgical tools guided by sub-cellular programmable computers will operate on the molecular level, enabling “the precise destruction of cancer cells and AIDS viruses.” Nanobots might conceivably build materials that are 100 times stronger than diamonds or high-quality graphite, Drexler says.

The technology is not as far off as it seems. The very real possibility of nanotechnology manufacturing was explored in a 2006 National Research Council report entitled A Matter of Size. Sensors for medical diagnostics, such as Drexler imagines, “are built every day with the aid of processes that exemplify molecular self-assembly,” the report says. “More complex structures can be generated by more sophisticated self-assembly processes.”

Today’s microelectronics factories use photolithographic processes to optically project patterns onto silicon wafers. Using this process, electronic circuits can be built with wires as narrow as 90 nanometers. Semiconductor manufacturers are working on the 65-nanometer level, and 45- and 32-nanometer manufacturing processes are underway. The report concludes, “There is no fundamental physical barrier to practicing lithography at atomic levels.”

The use of nano in biotechnology is also well advanced, and the re-engineering of cells for new purposes is firmly established. Biological processes can and likely will form the basis of many manufacturing processes.

In conclusion, the report’s authors see “an amazing future” for nanotechnology, including a distant time in which virtually any stable chemical structure can be built up atom by atom or molecule by molecule. The big challenge: The need to operate at very high speeds, with very low error rates and almost perfect thermodynamic efficiency.

But there are potential problems, too. In his 1986 book Engines of Creation (Anchor), Dr. Drexler imagined self-replicating nanomachines running amok, and breaking down biological material, eventually turning everything into “grey goo.” Author Bill McKibben popularized this frightful idea in his book Enough: Staying Human in an Engineered World (Times Books).

But Drexler himself has backed away from grey goo, though he still considers it “well within the realm of physical law.” Today, he says, “I thought it was important to outline a worst-case scenario.” But he doesn’t think self-replicating machines of the type that could turn us all into mush will ever be in widespread use. “I also underestimated the popularity of depictions of swarms of tiny nanobugs in science fiction and popular culture,” Drexler says.

Another worry is nanoweapons. The futurists Michael Vassar and Robert A. Freitas, Jr., imagine self-replicating attack systems called “ecophages’ making copies of themselves (ã la The Terminator) and eating the enemy or his resources as they self-replicate. They propose a nanoshield defense.

The authoritative Jane’s Defence Weekly suggests that the design of new chemical agents “that attack specific body organs such as the central nervous system would enable far smaller amounts of the chemical to be made without detection and would require only small, low-level facilities.” Non-lethal chemical weapons might also emerge to subdue belligerents for riot control and police work, Jane”s says.