Chasing rainbows in the Nanoworld?
06/01/2006
Nanotechnology is seen by many as “the next big thing.” It promises many new types of devices and effects that could be used in sensors, displays, light sources, and a host of other applications, in electronics as well as in a wide range of other fields.
Today, of course, most of these potential applications are in the early research phase, often with the underlying science still not well understood. Many are expected to depend on nature’s tendency toward self-organization. Unfortunately, although there are many examples of self-organization, without some prodding all tend to be somewhat messy. There may be small local regions of perfect alignment, size, and spacing, but this breaks down at the scales needed for useful devices. The hope is that we will master techniques allowing regular arrays to deposit themselves, somewhat like perfect crystals forming out of a melt. Once we understand the detailed dynamics and quantum forces of these self-organizing processes, the hope is that we will be able to bend nature’s mechanisms to our own needs in a “bottom up” fashion, whether forming microcrystals in a flash memory cell, regular arrays of light emitters or detectors, or other types of devices.
The world of biotechnology is full of self-assembled nanostructures. And another vision of nanotech pioneers is to mesh biotech with electronics and other chemical processes to form new types of devices, often using nature’s own mechanisms to form useful structures. This promises an efficient approach to fabrication rather than using the exacting and increasingly expensive methods of deposition, lithography, etching, implantation, and other top-down processes.
All we need, some believe, is better nanoscale measurement tools enabling scientists to observe nature’s building-block methods for self-organization. This will help us learn how to create conditions to improve these natural processes and create perfect arrays, much as had to be done (with some difficulty!) to develop zone refining of semiconductor materials to create single-crystal boules for wafermaking.
But the problems in nanotech may be tougher than most of us think. Physicists are now hotly debating a very pertinent issue-reductionist versus emergent science. The emergent view, ably presented by Robert B. Laughlin of Stanford U. in A Different Universe (Reinventing Physics from the Bottom Down), Basic Books, 2005, holds that Newtonian views of physics break down at quantum levels, where strange things happen that may be either very hard or impossible to measure. You cannot explain the ideal gas law by building it up from a model based on molecules bouncing around like billiard balls, argues Laughlin, who shared the Nobel Prize in physics in 1998 for work on the fractional quantum Hall effect. Many things in physics are actually collective phenomena, not amenable to explanation or prediction by isolating individual particles and building up theories based on their observed behavior. Phase changes (such as water to steam or ice) are like this. Even the holes and electrons in a semiconductor device must actually be viewed as entangled throughout the crystal lattice rather than being treated as isolated units.
In Laughlin’s view, there are many bad experiments in science and false theories based on them, and he especially singles out those working in biotechnology and nanotech, where quantum effects and collective phenomena may be very significant. Many experiments are really taking isolated snapshots of a dynamic process, and extrapolating from them is like trying to predict the outcome of a tug-of-war between closely matched teams by taking quick glimpses of the action along the way. He cites some work in biotech where varying results under the same experimental conditions are found by different groups, and sometimes even by the same researchers! Some phenomena, like phase changes, may not be amenable to reductionist methods at all, he believes.
Laughlin recognizes that commercial R&D often focuses on experiments aimed at developing or improving a practical process, rather than probing the underlying science, and he doesn’t deplore these methods. But a sector like nanotech with great commercial prospects has the potential to absorb millions of misspent research dollars chasing rainbows if the underlying science is not understood.
Fortunately, there are some far-seeing researchers who do recognize that we may not be able to completely harness nature to our will. At nanotech panel sessions, they speak about finding ways to make workable devices in spite of somewhat imperfect fabrication. Actually, memory designers already use some of these techniques, and error-correcting computing methods are being developed for nanoscale mesh networks.
Smart people in our industry can figure out how to make things work well in spite of a few unavoidable flaws. But with the limited resources available for inventing future technologies, we shouldn’t be spending a lot of money on silly science.
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Robert Haavind Editorial Director