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he said at the end of 1959, when the American Physical Society held its annual meeting at Caltech, “by which you can write the Lord’s Prayer on the head of a pin. But that’s nothing… .” On toward the atom, he urged them. “It is a staggeringly smal world that is below.”

That same pinhead could hold the twenty-four volumes of t h e Encyclopaedia Britannica , pictures and al , if the encyclopedia were reduced 25,000 times in each direction.

A modest reduction, considering that the barely visible dots making up a halftone photoengraving would stil contain a thousand or so atoms. For writing and reading this tiny Britannica , he proposed engineering techniques within the limits of contemporary technology: reversing the lenses of an electron microscope, for example, and focusing a beam of ions to a smal spot. At this scale, the world’s entire store of book knowledge could be carried about in a smal pamphlet. But direct reduction would be crude, he

continued. Telephones and computers had given rise to a new way of thinking about information, and in terms of raw information—al owing six or seven “bits” per letter and a generous one hundred atoms per bit—al the world’s books could be written in a cube no larger than a speck of dust.

His audience, unaccustomed to lectures of this kind at American Physical Society meetings, was enthral ed.

“Don’t tel me about microfilm!” Feynman declared.

He had several reasons for thinking about the mechanics of the atomic world. Although he did not say so, he had been pondering the second law of thermodynamics and the relationship between entropy and information; at atomic scales came the threshold where his calculations and thought experiments took place. The new genetics also brought such issues to the surface. He talked about DNA (fifty atoms per bit of information) and about the capacity of living organisms to build tiny machinery, not just for information storage but for manipulation and manufacturing.

He talked about computers: given mil ions of times more power, they would not just calculate faster but would reveal qualitatively different abilities, such as the ability to make judgments. “There is nothing I can see in the physical laws that says the computer elements cannot be made enormously smal er than they are now,” he said. He talked about problems of lubrication, and he talked about the realm where quantum-mechanical laws would take over. He envisioned machines that would make smal er machines, each of which would make machines that were smal er stil .

“It doesn’t cost anything for materials, you see. So I want to

build a bil ion tiny factories, models of each other, which are manufacturing simultaneously, dril ing holes, stamping parts, and so on.” He concluded by offering a pair of one-thousand-dol ar prizes: one for the first microscope-readable book page shrunk 25,000 times in each direction, and one for the first operating electric motor no larger than a 1/64th-inch cube.

Caltech’s magazine Engineering and Science printed Feynman’s talk, and it was widely reprinted elsewhere.

( Popular Science Monthly retitled it “How to Build an Automobile Smal er than This Dot.”) Twenty years later there was a name for the field Feynman had been trying to invent: nanotechnology. Nanotechnologists, partly inspired and partly crackpot, made tiny silicon gears with careful y etched teeth and displayed them proudly in their microscopes; or imagined tiny self-replicating robot doctors that would swim through one’s arteries. They thought of Feynman as their spiritual father, although he himself never returned to the subject. In the crude mechanical sense, tiny machines seemed a feature of a future just as distant as in 1959. The mechanical laws of physics meant that friction, viscosity, and electrical forces did not scale down as neatly as Feynman’s imagined bil ion tiny factories. Wheels, gears, and levers tended to glue themselves together. Tiny machines had come into being, storing and manipulating information even more efficiently than he had predicted. But they were electronic, not mechanical, using quantum mechanics, not fighting it. Not

until 1985 did Feynman have to pay the thousand dol ars for tiny writing: a Stanford University graduate student, Thomas H. Newman, spent a month shrinking the first page of A Tale of Two Cities onto silicon by almost exactly the technique Feynman had outlined.

The tiny motor did not take so long. Feynman had underestimated existing technology. A local engineer, Wil iam McLel an, read the Engineering and Science article in February. By June, when he had not heard any more, he decided he had better make the motor himself. It took two months of working in his spare time, using a watchmaker’s lathe and a microdril press, dril ing invisible holes and wrapping 1/2000th-inch copper wire. Tweezers were too crude. McLel an used a sharpened toothpick. The result was a one-mil ionth-horsepower motor.

One day in November he visited Feynman, who was working alone in a Caltech laboratory. McLel an brought his equipment in a large wooden box. He saw Feynman’s eyes glaze; too many cranks had turned up, typical y bringing toy automobile engines that they could hold in the palm of a hand. But McLel an opened his box and pul ed out a microscope.

“Uh-oh,” Feynman said. He had neglected to make any arrangements for funding the prize. He sent McLel an a personal check.

All His Knowledge

He could not let go of the simple questions. He had spent much of a lifetime assembling a picture of how the world worked, how atoms and forces conjoined to create ice crystals and rainbows. In conjuring a world of miniature machines, he continued to work out possibilities at the level of long-lived molecules, not ephemeral strange particles.

He had made himself a member of the community of theoretical physics, and he accepted their goals and their rhetoric: he had told the American Physical Society apologetical y that miniaturization was not “fundamental physics (in the sense of, ‘What are the strange particles?’).”

Indeed, his community now assigned a kind of intel ectual primacy to phenomena that could be observed only in the searing less-than-an-instant of a particle col ision. But a part of him stil preferred to give fundamental a different definition. “What we are talking about is real and at hand: Nature,” he wrote to a correspondent in India, who had, he thought, spent too much time reading about esoteric phenomena.

Learn by trying to understand simple things in terms of other ideas—always honestly and directly.

What keeps the clouds up, why can’t I see stars in the daytime, why do colors appear on oily water, what makes the lines on the surface of water being poured from a pitcher, why does a hanging lamp swing back and forth—and al the innumerable little things you see al around you. Then when you have learned what an explanation real y is, you can then go on to more subtle

questions.

The first plank in every Caltech undergraduate education was a two-year required course in basic physics. By the 1960s the institute administration recognized a problem.

The course had grown stale. Too much ancient pedagogy lingered in it. Bright young freshmen arrived from their high schools around the country, ready to tackle the mysteries of relativity and strange particles, and were plunged into the study of—as Feynman put it—“pith bal s and inclined planes.” There was no main lecturer; the course met in sections taught by graduate students. The administration decided in 1961 to revise the course from the bottom up and asked Feynman to take it on for one year. He would have to lecture twice a week.

Caltech was not alone; nor was physics. The pace of change in modern science had accelerated as most col ege syl abuses had hardened. It was no longer possible, as it had been a generation before, to bring undergraduates up to the live frontier of a field like physics or biology. Yet if quantum mechanics or molecular genetics could not be integrated into undergraduate education, science risked becoming a historical subject. Many first-year physics courses did begin with history: physics in ancient Greece; the pyramids of Egypt and the calendars of Sumeria; medieval physics through nineteenth-century physics. Virtual y al began with some form of mechanics. A typical program went: