The popular idea of so-called nanobots, powerful and at risk of running wild, is not part of modern plans for building things “atom-by-atom” by molecular manufacturing. Studies indicate that most people don't know the difference between molecular manufacturing, nanoscale technology, and nanobots. Confusion about terms, fueled by science fiction, has distorted the truth about advanced nanotechnology. Nanobots are not needed for manufacturing, but continued misunderstanding may hinder research into highly beneficial technologies and discussion of the real dangers.
Nanobots have plagued nanotechnology from the beginning. Eric Drexler’s Engines of Creation (1986), which introduced nanotechnology to the public, described certain kinds of tiny robots with limited capability. But in some fiction and fanciful speculation, these “nanorobots” or “nanobots” possess near-magical powers: transforming any object into anything else, acting as a universal medical device, or destroying anything they touch. This idea has caused confusion about the actual goals of advanced nanotechnology research.
Originally, nanotechnology was about building stuff from the atoms up. “Assemblers” were specialized molecular construction machines. “Disassemblers” were research tools to figure out how to make things. A programmable atom-based manufacturing system would be able to build as many more systems as desired. But all these ideas merged with the nanobot concept, plus a heavy dose of science fiction, to create the idea of a single machine that could do it all—and might run wild, turning the world into a “gray goo” of self-copies.
Meanwhile, the meaning of “nanotechnology” was being stretched. As funding opportunities increased, researchers in related and distant fields of nanoscale technology adopted the term to describe work they'd been doing for decades. By 1992, Drexler had to coin “molecular manufacturing” and “molecular nanotechnology” to indicate what he originally meant by nanotechnology.
Studies have shown that most readers don't know the difference between molecular manufacturing, nanoscale technology, and nanobots. Most nanoscale technologies use big machines to make small products. Molecular manufacturing is about tiny manufacturing systems. But those manufacturing systems are not nanobots. Modern plans for molecular manufacturing do not involve self-contained nanoscale construction robots at all.
No one worries about an inkjet printer crawling off the desk and stealing ink cartridges. Molecular manufacturing systems will be no more autonomous than inkjets. Early, primitive, microscopic systems will not even have onboard computers. In advanced designs, called nanofactories, the molecular fabrication apparatus will all be fastened down in well-ordered ranks inside a much larger structure. All designs will be externally controlled and supplied, capable of producing a duplicate nanofactory in about an hour—but only on command.
As nanoscale technologies begin to move from the lab to the marketplace, and attention turns to molecular manufacturing research, it will be increasingly important for journalists to counter outdated and incorrect ideas of nanotechnology and molecular manufacturing. Both scientists and the public have gotten the idea that molecular manufacturing requires the use of nanobots, and they may criticize or fear it on that basis. The truth is less sensational, but its implications are equally compelling.
 Nanotechnology has several definitions. Today, a widely accepted definition is any technology involving structures between 1 and 100 nanometers with novel properties. (A nanometer is a billionth of a meter, roughly the length your fingernails grow in one second.) There are many ways of building nanoscale structures and materials, and for each there is a different branch of nanotechnology. Most of these nanoscale technologies use large tools to create small structures. In general, these can be understood as traditional industrial or chemical processes, and not the same thing as molecular manufacturing. For more, see What is Nanotechnology? and What is Molecular Manufacturing?
 For more on this worry, see Gray Goo is a Small Issue.
 In the long term, some products of molecular manufacturing systems could be nanobots (e.g., for medical use), but these are not envisioned to be metabolizing or self-replicating (at least not by credible researchers).
 See Bootstrapping a Nanofactory.
 For information on the risks and benefits of advanced nanotechnology, see CRN Research: Overview of Current Findings.
A permanent link to this briefing document is at http://CRNano.org/BD-Nanobots.htm