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O Nature, and O soul of man! how far beyond all utterance are your linked analogies! Not the smallest atom stirs or lives on matter, but has its cunning duplicate in mind. -Herman Melville. Moby Dick [1851)
THE HARDEST THING YOU CAN ASK THEM is how old they are. The question seems to rock them back, to give them pause. "I guess I'm 38," one of them tells me uncertainly. "I must be 54," another answers, after even longer deliberation. It's not that these men are slow, it's that they're physicists. And they're involved in a research area as promising as it is new and strange, so if they seem a little distracted, well, c'est la vie. Despite a cautious modesty so deeply ingrained that it might well be genetic, they also project an air of barely contained excitement. They're building a magical future, and they know it.
Through the entirety of human history, from the moment the first stone was picked up and hurled at an attacking predator, our lives have been shaped and focused and empowered by our technology. Nature would have us naked and unprotected, scrabbling in the dirt for sustenance; we prefer to be clothed and warm, well nourished, and equipped with a variety of tools to shape and interact with the environment around us. Initially these tools were found objects: sticks and stones. Later, we began to shape them for specific purposes, and then to connect them in intricate ways. We progressed from tools-static pieces of specialized matter-to machines, which are tools that can change their shape, and convert energy from one form to another. Matter that works, so you don't have to. Soon, we were experimenting with abacuses, and with animated models of the heavens known as "orreries." These led directly to mechanical calculating machines, and eventually to designs for general-purpose computers-matter that thinks. This idea no longer shocks us-we've lived with computers for too long-but there is nothing natural about it.
Technology is literally the study of technique, but by the twentieth century it had become possible to study technology itself-the changes and directions and underlying motivations of the invented world, and the possibilities that might soon arise. The literature of science fiction took note of these observations, and, indeed, in his 1962 collection Profiles of the Future, writer and visionary Sir Arthur C. Clarke formalized three "laws" of technological development:
First Law: "When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong."
Second Law: "The only way of discovering the limits of the possible is to venture a little way past them into the impossible."
Third Law: "Any sufficiently advanced technology is indistinguishable from magic."
The first two laws are largely forgotten, and the third, commonly known as "Clarke's Law," was actually stated less succinctly in the 1940s, based on a similar comment made by the alchemist Roger Bacon some 700 years prior, when he wrote of crude eyeglasses and telescopes and microscopes and described them as a "natural magic." What Bacon observed, and Clarke formalized, is that the ultimate aim of technology is simple wish fulfillment.
"Magic" has been technology's partner from the very beginning-a similar attempt to grasp and shape the forces of the world. Any anthropologist will tell you that magic is a rational belief based on sound principles of analogy and empiricism. Unfortunately, it has been far less successful than its partner. We yearn for it, write poems about it, but fred no hard evidence for it in our world. The magic we examine turns out to be coincidence or natural processes, or outright trickery. But here is the corollary of Clarke's Law: that trickery is also a technology, and one that fulfills a definite human need. We use the levers and pulleys of technology to shape our world, but what we really want is a world that obeys our spoken commands and reconfigures itself to our unvoiced wishes. What we really want-what we've always wanted-is magic.
The future is where these two notions converge. If matter can work and think, can it also be made to obey, at some fundamental, nearmagical level? The answer I will give here is not a simple yes or no, but a survey of a class of electronic components called "quantum dots" and their possible application to the fields of computing and materials science.
This is not a book about "nanotechnology" in any of its popular incarnations. Nor will I spend much time discussing the nearer-term technology of microelectromechanical systems, or MEMS, which has already found its way into some applications. The future almost certainly holds myriad uses for both of these, but by the time they find their way into the real world, they may wind up looking less magical than a humble television screen, which after all can change its appearance instantly and completely. But there may be a truly programmable substance in our future that is capable of changing its apparent physical and chemical properties as easily as a TV screen changes color. Call it programmable matter.
Before we begin, it's helpful to clarify the issue of scale. Virtually everyone is familiar with the millimeter (mm), a unit of length equal to one tenth of a centimeter or 0.03937 inches. This is the smallest of the everyday units that nonscientists use in normal life. People in the medical and electronics professions may be almost as familiar with the much smaller micron or micrometer (µm), which represents one thousandth of a millimeter the primary unit for measuring microscopic things, whether living or non-. Only a handful of professionals (mainly chemists and physicists) are interested in the nanometer (nm), which is one thousandth of a micron or one millionth of a millimeter. This is the scale of molecules, and it is generally invisible to us even with optical microscopes. There are still smaller units, such as the Angstrom (0.1 nm), picometer (0.001 nm), and Planck length ([1.610.sup.-26] nm), but for the purposes of this book, these are awkward and will be avoided. Similarly, since the objects and devices we'll be considering are mainly microscopic, the millimeter is a bloated unit for anything other than occasional reference. For the next seven chapters, we'll be dealing heavily in microns and especially nanometers, so Table 1.1 is provided to show how familiar objects stack up against these measurements. If you get confused later on in the book, checking back here may help.
In the microscopic realm, scale is of critical importance. On the macroscale-the familiar world of meters and millimeters and kilometers-the laws of physics are essentially the same regardless of how big or small an object is. Gravity and electromagnetism have the same effect on stars and planets as they do on pebbles and sand grains. This rule holds true in the upper reaches of the microscopic realm as well: red blood cells (about 10 µm across) can be modeled quite well with the equations of classical dynamics and fluid mechanics.
At the nanoscale, where we find very tiny, very simple objects like the water molecule (about 0.3 nm across at its widest), these rules barely apply at all. Instead, the behavior of particles is governed by quantum mechanics, that elusive and slippery physics pioneered in the time of Einstein. Quantum mechanics is almost completely counterintuitive; your "gut feel" about how a particle should behave is virtually useless for predicting what it will actually do. This is because on the nanoscale, what we call "particles" are really "probability waves"-regions where a particle-like phenomenon is more or less likely to occur. Probability waves can do "impossible" things like leaping across an impenetrable barrier, or existing in many places at the same time, or apparently predicting the future, or being influenced by distant events much faster than the speed of light should allow.
But this intuitive mess is at least orderly in a mathematical sense, and is well described by the "quantum field theory" of the early and middle twentieth century. Small molecules possess a high degree of symmetry and a relatively small number of constituent particles (or waves). As a result, their behavior under various circumstances can be predicted with great accuracy, even though it makes no apparent sense to us as human beings.
So the microscale of the red blood cell is a very different place from the nanoscale of the water molecule. The mathematics that describe them are completely different. But these two scales are separated by three orders of magnitude (i.e., by a factor of 1,000) in size, and between them lies a mysterious realm called the mesoscale (from the Greek "mesos," or middle), where neither set of theories is accurate. The equations of quantum field theory become exponentially more complicated as the number and size of particles increase-especially because random voids and impurities creep in, disrupting the quantum waveforms in unpredictable ways. So while quantum theory is highly accurate, its predictions tend to be almost worthless on the mesoscale.
Similarly, the classical "laws of physics" are really just statistical observations-the averaged behavior of large groups of atoms. But these averages, like any statistics, lose their validity as the sample size decreases. There is no "average particle," just as there's no "average human being" or "average hockey game." Objects much smaller than a micron in size start to behave in some very non-Newtonian ways, as the nonaverage behavior of individual particles increasingly stands out.
So if mesoscale physics are neither classical nor quantum, we clearly need some entirely new set of theories to describe them. This will be an important frontier for physics and chemistry as the twenty-first century unfolds. Meanwhile, our shrinking electronics technology is creeping down into the mesoscale whether we're ready or not, and our increasingly large and sophisticated designer molecules are unfortunately creeping up into the same realm from the other direction. Experimentation on the mesoscale-to give us at least some marginal information about where we're headed-has been a hotbed of activity since the late 1980s.
The study of mesoscale effects is an important aspect of "condensed matter physics," which Britannica defines as "the study of the thermal, elastic, electrical, magnetic, and optical properties of solid and liquid substances." It is here in this scientific hinterland that we fred Drs. Marc Kastner, Moungi Bawendi, Charles Marcus, and Raymond Ashoori. Their specialty: mesoscopic semiconductor structures with bizarre new properties.
Some of their early discoveries are quite astonishing.
Already we know the varieties of atoms; we are beginning to know the forces that bind them together; soon we shall be doing this in a way to suit our own purposes. The result-not so very distant-will probably be the passing of the age of metals.... Instead we should have a world of fabric materials, light and elastic, strong only for the purposes for which they are being used. -John Bernal, "The World, the Flesh, and the Devil" (speech, 1929)
BOSTON IS A CHALLENGING CITY to get around in even if you have a good map, a good sense of direction, and a mile-wide destination right on the banks of the Charles River. One wrong turn, and you're lost among narrow one-way streets that are hundreds of years older than the automobile. From hilltops and between buildings you may glimpse the bridges that lead across into Cambridge, though never via the road you're actually on. You may even see MIT itself it's an imposing collection of cement and sandstone edifices, giant columns, and very tall buildings for a university. Of course, there are five other college campuses in the immediate area, plus hospitals and museums and government centers to confuse the unwary. Also identical parking garages that will happily charge you $20 for an afternoon.
But rest assured, you'll get there. MIT is as ugly as it is hard to reach, and it sticks up out of the city like a bouquet of sore thumbs. Universities are quirky by nature, but here quirkiness seems to be a point of pride; the scale of the place, while impressive, dictates that it can't really be imaged or photographed except possibly from the air. The buildings are too large, too close together, too close to other things to fit in a camera lens, and anyway every square and courtyard boasts a big, ugly, nonrepresentational sculpture that seems calculated to repel photographs. Most quirkily, what appear on the map as separate buildings are in fact all connected like a giant Victorian shopping mall, through a gloomy central passage known as the "Infinite Corridor." The occasional south-facing window, looking out across the river at the towers of Boston, half a mile and a few dozen IQ points away, provides the only real connection with the world as most people know it. By American standards this place is old-everywhere you find doorknobs worn smooth, staircases bowed like grain chutes, stone benches so old they sag in the middle, flowing over centuries like benchshaped sculptures of molasses.
The decor is schizophrenic as well: here a row of old classrooms, there a carved monument to the university's war dead. The bulletin boards are adorned with notices of various kinds: some political, some artistic, some related purely to student life. Many of them are ads from and for extremely specialized technical journals, conferences, and job postings. Now we pass through a set of double doors, up a few flights of well-hidden stairs, and into a red-painted hallway lined with pressure tanks and cryogenic dewars and other heavy and vaguely dangerouslooking equipment. Suddenly there are a lot of warning signs:
WARNING: High Magnetic Field
WARNING: Potential Asphyxiant. May cause severe frostbite.
Wear Eye Protection
And my personal favorite,
CAUTION: Designated area for use of particularly hazardous chemicals. May include select carcinogens, reproductive toxins, and substances with a high degree of acute or chronic toxicity. Authorized personnel only.
Interestingly, that notice is dated 1990, and curls up noticeably at its yellowed corners.
We are, to put it mildly, not in Kansas anymore. We've entered the Center for Materials Science and Engineering, a fey landscape whose residents would be appalled to describe it as "magical." The drinking fountains don't work, for one thing. Nonetheless, the air virtually crackles with subdued excitement.
Excerpted from Hacking Matter by Wil McCarthy Copyright © 2004 by Wil McCarthy. Excerpted by permission.
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|Programmable Matter: A Retrospective|
|1||Clarke's Law and the Need for Magic||1|
|3||The Play of Light||39|
|4||Thermodynamics and the Limits of the Possible||61|
|5||Magnetism and Mechanics||89|
|6||The Point-and-Click Promise||113|
|7||The Programmable City||133|
|8||The Future Tense||151|
|Afterword: Accidental Demigods?||171|
|App. A: References||175|
|App. B: Patent Application||185|