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By John Toon |
IN THE 1997 MOTION PICTURE "Men in Black," extraterrestrial forces threaten to destroy Earth unless a stolen galaxy is quickly returned. The turning point of the story comes when the good guys realize that galaxies can be small enough to fit in a pocket.
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Just how small is nanoscale? A nanometer is one-billionth of a meter. Written as a fraction, that would be 1/1,000,000,000th of a meter. Five hydrogen atoms side by side span about one nanometer. The cells of our bodies stretch into the thousands of nanometers. At 100,000 nanometers, that old standby for size comparisons – the width of a human hair – seems positively gigantic. The head of a pin measures a million nanometers.
But smallness alone does not account for all the interest in the nanoscale. Because they share size scales with light waves and interact with electrons that can no longer behave like particles, nanoscale structures push the envelope of physics, moving into the strange world of quantum mechanics. That's both good and bad, offering challenges and opportunities.
Building a nanomachine or nanostructure therefore involves more than scaling everything down. At nanometer sizes, inertia critical to old-fashioned motors no longer has meaning. Friction changes, and gravity hardly matters. Nanoscale versions of materials differ significantly from those same materials at "bulk" sizes.
Beyond unique properties, the nanoworld offers the possibility of creating materials that have never existed before, building anew from the atom up. Using breakthrough tools like the scanning probe microscope, researchers can already move atoms around like checkers on a board.
"This is the next technology revolution," says Zhong L. Wang, director of Georgia Tech's Center for Nanoscience and Nanotechnology and a professor in the School of Materials Science and Engineering. "Nanotechnology will allow us to achieve revolutionary advances in many different areas. It's a very broad science, and will impact each and everyone's life."
Wang counts five advances that make the nanorevolution possible:
- Development of the scanning and transmission electron microscopes and scanning tunneling and atomic force microscopes, revolutionary technologies allowing researchers to see the nanoworld, even manipulate it.
- Nanoscale devices and engineering as the critical challenge to the future roadmap for microelectronics.
- Development of novel structures, such as fullerenes and carbon nanotubes, breakthrough structures that helped scientists realize the potential of the nanoworld.
- Appreciation for the effects of quantum mechanics, and structures such as quantum dots to take advantage of them.
- Powerful computers and software powering simulations to allow scientists to understand the phenomena at nanoscales.
Ashok Saxena, chair of Georgia Tech's School of Materials Science and Engineering, notes that every important advance must overcome unforeseen difficulties moving from the lab to real-world application. He compares today's nanoscience and nanotechnology to the burst of enthusiasm greeting advances in superconductivity during the mid-1980s.
"It was supposed to be revolutionary and change a lot of things," he notes. "We are only now beginning to see devices that use superconducting materials. Only time will tell how significant the contributions made by nanoscience and nanotechnology will be."
Others suggest the real implications may be beyond our current grasp.
"The most important results might not even be the things we are thinking about today," says Mostafa El-Sayed, Regents Professor of chemistry and director of the Laser Dynamics Laboratory. "I don't think it will be as great as some people predict, but there will certainly be interesting developments coming out of it."
Success in the nanoworld demands a different way of thinking – perhaps not unlike the good guys who had to accept the idea of a pocket-sized galaxy to save the Earth.
"We are still thinking with the mind of the huge world," El-Sayed says. "We may find that some of what we think are problems, in that small world are really very useful. We just don't know where it will lead. There is a lot of science yet to be done before the engineers can work with it."
For more information, contact Zhong Wang, School of Materials, Science and Engineering, Georgia Tech, Atlanta, GA 30332-0245. (Telephone: 404-894-8008) (E-mail: zhong.wang@mse.gatech.edu)
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Last updated: July 14, 2001