Nanotechnology is really very counterintuitive, even to scientists. Here are two definitions that may be helpful.
Nanotechnology is the transition from the classical to the quantum regime. Nanotechnology involves the design and use of quantum-based properties of a material. Typically the transition from classical to quantum properties occurs at dimensions of 30 nanometers or less. It's important to realize that there is a great deal of latitude in this transition state. Perhaps one of the best definitions of nanotechnology was from a talk given by Paul Alivisatos where he pointed out that there are a half dozen different forces, ranging from charge attraction to Van der Waals forces which have varying dependences on r, from r2 to r6. Thus, this classical/quantum transition doesn't happen at the same size regime for all the properties under discussion.
Nanotechnology is really about how atoms are assembled into larger structures. Assembling atoms isn't like putting pieces into a puzzle where they can only go one way. It's more like a Lego set - you have a bunch of pieces that have to be assembled with their neighbors in several restricted ways, but what you build overall is pretty wide open. Nanotechnology is discovering that the Lego pieces fit together in some new and different ways.
The Evolution of Nanotechnology
In 1959 Richard Feynman gave his now famous lecture, "There's always room at the bottom." In this lecture and subsequent article, he pointed out that there were no theoretical limitations to building or modifying molecules atom by atom. However, Feynman wasn't the first person to notice that changing a nanostructure altered the properties of materials. In the 1920s, it was commonly understood in metallurgy that nanosized crystalline grain structures altered the ductility, tensile strength, modulus, and impact strength of metals- changes which metal workers had been doing for years with repeated heating, quenching and hammer blows. X-ray crystallography revealed that metal alloys were often composed of nanocrystalline grains in a matrix. Unfortunately chemists were extremely limited in finding nanostructured materials other than metals for decades.
Nature was also providing lots of hints about the importance of nanostructures. Molecules such as DNA showed the importance of nanostructure to cellular processes. How DNA was folded affects replication, and many of the systems that nature has developed such as DNA transcription, protein production, photosynthesis etc. all operate on the nanoscale.
Unfortunately, the tools to examine these processes were lacking in the first half of the twentieth century, and there was little theoretical development as well. However, in the mid 1970s through the 1980s, a variety of microscope technologies were developed that allowed chemists and materials scientists to really examine what was happening at the nanoscale. Atomic Force Microscopy (AFM) allows scientists to move and image surfaces with atomically fine probes-effectively braille on an atomic basis. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) fill out the set. These microscopes produce the familiar black and white images of things from dust mites to atoms spelling out IBM.
In the mid 1980s and early 1990s, the discovery of novel structures such as buckeyballs and nanotubes also drove scientific interest in materials at the nanoscale. However, funding for nanotechnology was being spread throughout the scientific research base, and was not achieving critical mass for breakthroughs to be made. Mike Rocco (with assistance from others) became the point man on a nanotechnology interagency working group which is often regarded as the driving force behind the National Nanotechnology Initiative, set up in the late 1990s.
Scientists are often driven more by curiosity than economics, but with funding tight, the need to help justify research led to some high-profile political announcements, including the 21st Century Nanotechnology Research and Development Act.
Today, research involving novel nanostructures (unknown prior to 2000) is making progress at a rapid rate. Roughly a quarter of the papers at the 2005 MRS (Materials Research Society) meeting involved comparing nanostructured materials to conventional bulk materials, while nanostructured materials played a role in about half of the talks. The concepts of nanotechnology are here to stay and are being integrated into mainstream science.