Small Wonders

Local scientists are shrinking chips and wires to atomic scale, revolutionizing the electronics industry. But most of the nanotechnological advances you've read about are outsized hype.

In 1992, Drexler, an engineer, went beyond predicting the general emergence of nanotechnology: He wrote a book, Nanosystems, detailing technical particulars. Paul McEuen and several of his colleagues say that Drexler's drawings of nanothings are just molecule-sized versions of mechanical devices that have been around for centuries: gears, cogs, levers, and pistons. If Drexler's peculiar versions of nanomachines some- day materialize, working physicists say, his engineer's calculations, which hold true in the world most people comprehend, will not be of much use in the realm of the very, very small, because that world is governed by strange scientific laws known collectively as quantum mechanics.


Scientific investigations of large objects, such as planets and solar systems, are done via classical physics, the rules of the universe we know and love. Classical physics declares that nothing is uncertain, only a consequence of some earlier cause. And until quantum theory came along at the dawn of the 20th century, the cause-and-effect determinism of classical physics seemed undeniably true. Isaac Newton's mechanics of motion, such as gravity and centripetal force, applied equally to solar systems and children's merry-go-rounds. James Clerk Maxwell's theories of electromagnetism showed that electricity and magnetism are two sides of the same coin. Technologies developed by classical science lit up our cities and sent people to the moon.

Hongjie Dai.
Courtesy of IBM Research Division
Hongjie Dai.
Mike Crommie with his scanning tunneling microscope.
Courtesy of Hongjie Dai
Mike Crommie with his scanning tunneling microscope.

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RELATED LINKS

"Brave New Nano-World Lies Ahead: One atom at a time, scientists are building a future of the fantastic"
San Francisco Chronicle
July 19, 1999

Foresight Institute
Official site of Eric Drexler's Palo Alto-based futurist organization

McEuen Group
Home page of Paul L. McEuen's research group at the University of California, Berkeley

Dai Lab
Home page of Hongjie Dai's Stanford University-based research group

Marcus Lab
Home page of Charles Marcus' Stanford University-based research group


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But the behavior of extremely small objects, such as elementary particles, is best described by quantum mechanics, the rules of the atomic world. For nearly 100 years, particle physicists -- or nanoscientists -- have tested the power of their quantum theories by measuring the properties of atoms and subatomic particles such as electrons. So far in human history, the machines invented by combining the knowledge of quantum mechanics with the lessons of classical physics have included televisions, nuclear weapons and reactors, and medical imaging devices.

It is easy to imagine the universe as a giant machine subject to celestial stresses and strains and cause and effect. In classical thought, apples fall off trees and stay there, instead of magically tunneling through the ground, as is possible (although improbable) in quantum mechanics.

Quantum mechanics is counterintuitive in the extreme. Even its most famous practitioners, Neils Bohr and Albert Einstein, were utterly perplexed as to how or why quantum mechanics works. But it does work, in the sense that it accurately predicts the behavior of the tiniest components of the universe. In doing so, it turns the laws of classical physics upside down.

At the quantum level, electrical current can no longer be handled as if it is a continuous stream of energy; when observed at the smallest level, electrical energy comes and goes in discrete little electron packages, instead of constant, measurable flows of juice.

At the quantum level, conventional measuring techniques collapse into meaninglessness. There, taking a measurement is no longer an objective act. It becomes subjective -- the act of measuring changes the reality that is measured. For instance, the quantum mechanical rules and regulations, which are well-known and codified, do not allow electrons, the charged particles that make up electrical current, to be simultaneously measured for speed and place. If you want to know how fast an electron is moving you can never know its position in space at the moment you measure, or observe, its velocity. And vice versa. This contradiction is called the uncertainty principle.

Classical physics glories in grasping how the individual parts of a system connect to determine the larger picture. But the larger picture underlying quantum mechanics is, above all else, indeterminate. That is to say, human consciousness cannot perceive a quantum system as a whole, orderly system built from individually relating parts.

Because of the quantum uncertainty principle, the act of observing a small quantum system -- such as electrons flying around the nucleus of an atom -- destroys the coherence, the inherent orderliness, of the quantum system. In scientific parlance, what is coherent "decoheres." And that is a good thing. Without decoherence our classical universe would blink out of existence, and our personal electrons would disappear into the cosmic stew. (Another way of looking at this phenomenon is that observing the orderly, self-coherent quantum world from the point of view of the classical world introduces chaos, or randomness, into the quantum world, allowing it to be observable. In short, what is called order in one system can be called chaos in another.)

Now, it is becoming possible to build structures so small that they operate independently of the world ruled by classical physics, devices so tiny that they directly link to the invisible quantum universe that lurks inside everything. And while there are no nanomachines yet in existence, there are nanostructures at sizes ranging from less than a billionth of a meter up to 10, or maybe 100, nanometers. (In this sense, a machine is defined as a device with a definite function, like an engine or microchip; structures are more passive objects and tend to be pieces of potential machines.)

Scientists and industrial corporations are betting that these tiny apparatuses will become the foundations of a new technological order. Public and private money is being heavily pumped into the research of nanoscientists. The intended effect is to revolutionize the classical manufacturing methods currently used by the consumer electronics industry. A technology based on quantum mechanics may not be just around the corner, but is a holy grail for futurist crusaders and down-to-earth experimentalists alike.

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