Nanotechnology will mean complete control of the structure of matter, building complex objects with molecular precision. It doesn't exist yet, because we don't have molecular assemblers yet. Work related to nanotechnology accordingly falls into two broad areas: the study of nanotechnology itself (which must remain theoretical, for the time being) and research on enabling technologies leading toward assemblers and nanotechnology (which can be theoretical in part, but which also has an experimental, developmental component).
"Because we lack the tools to do real nanotechnology today, these theoretical studies amount to building castles in the air."
The theoretical study of nanotechnology involves exploratory engineering work in any of several of areas. It includes basic studies in nanomechanical engineering (the study of molecular machines) and nanoelectrical engineering (the study of molecular and atomically-precise nanometer scale electronic systems). It also includes studies of complex systems, such as assemblers, replicators, and nanocomputers. More broadly, it includes studies of non-nanoscale applications, such as large systems built by teams of assemblers.
Because we lack the tools to do real nanotechnology today, these theoretical studies amount to building castles in the air. Accordingly, there is little funding for such efforts and frequent skepticism about their value. Nonetheless, such studies can be pursued with intellectual discipline, yielding firm results and a better understanding of our choices as a society. They have been my main focus and have spawned the current interest in nanotechnology—including the interest in giving these theoretical castles hardware foundations.
Studying what can be done with assemblers yields more foresight than it does progress; working to develop assemblers yields more progress than it does foresight. Inevitably, more resources will go into development than into theory, because technology development will yield practical, short-term results on the way to long-term objectives. It makes no practical sense to try to build an assembler today, but it does make sense to build tools today that will make it easier to build assemblers tomorrow. These tools are termed "enabling technologies."
Promising enabling technologies fall into several familiar categories. These include:
• protein engineering (involving efforts to develop techniques for designing molecular devices made of protein)
• general macromolecular engineering (involving efforts to develop techniques for designing and synthesizing molecular devices made of more tractable materials)
• micromanipulation techniques (involving efforts to extend the technology of scanning tunneling and atomic force microscopy to chemical synthesis, and then to the construction of molecular devices)
These approaches have differing strengths and weaknesses. Protein engineering can draw on a host of examples and prototypes from nature, and can exploit existing self-replicating machines (bacteria) to make products cheaply—a major consideration, where short-term payoffs are concerned. General macromolecular engineering avoids the major problem with protein engineering (proteins, not having been designed for designability, are hard to design), but at the cost of moving away from natural prototypes and requiring more expensive chemical synthesis techniques for making near-term products (thus reducing the potential market). Micromanipulation techniques promise to ease design problems by allowing direct construction of molecular objects, but they suffer from higher costs: a chemical reaction typically makes many trillions of molecules at once, while a manipulator would make but one, hence manipulator-made products can be expected to cost trillions of times more, dramatically reducing the potential market. Also, as of this writing , micromanipulation has not achieved even a single chemically-specific step in molecular synthesis, while chemists have built specific molecules containing thousands of atoms.
All the above areas bear watching, and all will be pursued to some extent, regardless of which ultimately proves to have the biggest payoff. Hybrid approaches, combining techniques from several of these areas (e.g., micromanipulation of molecular tools), seem promising.
Finally, improved computational modeling of molecular systems is a generic enabling technology, relevant to all these approaches.
Nanotechnology is fundamentally a branch of engineering.
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