Джеймс Глик - Genius - The Life and Science of Richard Feynman

The saga continues. Blocks vanish beneath the dirty water of a bathtub, and further calculations are needed to infer the number from the rising water level. “In the gradual increase in the complexity of her world,” Feynman said, “she finds a whole series of terms representing ways of calculating how many blocks are in places where she is not al owed to look.” One difference, he warned: in the case of energy, there are no blocks—just a set of abstract and increasingly intricate formulas which must always, in the end, return the physicist to his starting point.

With the vivid analogies and large themes immediately came computation. In the same one-hour lecture on the conservation of energy, Feynman had his students calculating potential and kinetic energy in a gravitational field. A week later, when he introduced the uncertainty

principle of quantum mechanics, he not only conveyed the philosophical drama of this “inherent fuzziness” in the description of nature but also leapt through the calculation of the probability density of an undisturbed hydrogen atom.

He stil had not reached the basics of speed, distance, and acceleration.

No wonder his col eagues found their nerves jangling as they tried to write problem sets. Before a half-year was gone, he was teaching an uncompromising version of the geometry of relativistic space-time, complete with particle diagrams, geometrical transformations, and four-vector algebra. For col ege freshmen this was difficult. Along with the mathematics Feynman tried to convey a feeling for how he visualized such problems, placing his “brain” into his diagrams like Alice plunging through the Looking-Glass. He tried to make his students imagine the apparent width and depth of an object:

They depend upon how we look at it; when we move to a new position, our brain immediately recalculates the width and the depth. But our brain does not immediately recalculate coordinates and time when we move at high speed, because we have had no effective experience of going nearly as fast as light to appreciate the fact that time and space are also of the same nature.

The students were sometimes terrified. Yet Feynman also returned to the standard fare of an introductory physics

course. When he covered centers of mass and spinning gyroscopes, experienced physicists realized that he was giving the students not just the mathematical methods but also original, physical understanding. Why does a spinning top stand upright on your fingertip and then, as gravity pul s its axis downward, slowly circle about? Even physicists felt they were learning the why for the first time when they heard Feynman explain that the gyroscope began by “fal ing” an invisibly smal distance … (He did not want to leave the students thinking a gyroscope was a miracle: “It is a wonderful thing, but it is not a miracle.”) No realm of science was out of bounds. After consulting with experts in other fields, he gave two lectures on the physiology of the eye and the physiochemistry of color vision, making a profound connection between psychology and physics. He described the view of time and fields that arose from advanced and retarded potentials, his graduate work with Wheeler. He delivered a special lecture on the principle of least action, beginning with his high-school memories of his teacher Mr. Bader—how does a bal know what path to fol ow?—and ending with least action in quantum mechanics. He devoted an entire lecture to one of the simplest of mechanical gadgets, the ratchet and pawl, the sawtoothed device that keeps a watch spring from unwinding—but it was a lesson in reversibility and irreversibility, in disorder and entropy. Before he was done he had linked the macroscopic behavior of the ratchet and pawl to the events occurring at the level of its constituent atoms. The history of one ratchet was also the

thermodynamic history of the universe, he showed: The ratchet and pawl works in only one direction because it has some ultimate contact with the rest of the universe… . Because we cool off the earth and get heat from the sun, the ratchets and pawls that we make can turn one way… . It cannot be completely understood until the mystery of the beginnings of the history of the universe are reduced stil further from speculation to scientific understanding.

The course was a magisterial achievement: word was spreading through the scientific community even before it ended. But it was not for freshmen. As the months went on, the examination results left Feynman shocked and discouraged. Stil , when the year ended, the administration pleaded with him to keep on for a second year, teaching the same students, now sophomores. He did, final y trying to teach a thorough subcourse in quantum mechanics, again reversing the conventional order. Another Caltech physicist, David Goodstein, said long afterward, “I’ve spoken to some of those students in recent times, and in the gentle glow of dim memory, each has told me that having two years of physics from Feynman himself was the experience of a lifetime.” The reality was different: As the course wore on, attendance by the kids at the lectures started dropping alarmingly, but at the same time, more and more faculty and graduate

students started attending, so the room stayed ful , and Feynman may never have known he was losing his intended audience.

This was the world according to Feynman. No scientist since Newton had so ambitiously and so unconventional y set down the ful measure of his knowledge of the world—

his own knowledge and his community’s. With intensive editing by other physicists, chiefly Robert B. Leighton and Matthew Sands, the lectures became the famous “red books”—the three-volume Feynman Lectures on Physics .

Col eges and universities worldwide tried to adopt them as textbooks and then, inevitably, gave them up for more manageable and less radical alternatives. Unlike true textbooks, however, Feynman’s volumes continued to sel steadily a generation later.

Adorning each volume was a picture of Feynman in shirtsleeves, gleeful y pounding a bongo drum. He came to regret that. “It is odd,” he said after hearing himself introduced yet again as a bongo player, “but on the infrequent occasions when I have been cal ed upon in a formal place to play the bongo drums, the introducer never seems to find it necessary to mention that I also do theoretical physics. I believe that is probably because we respect the arts more than the sciences.” And when yet another request came in for a copy of the photograph—

from a Swedish encyclopedia publisher who wished to

“give a human approach to a presentation of the difficult matter that theoretical physics represents”—he exploded.

“Dear Sir,” he scrawled,

The fact that I beat a drum has nothing to do with the fact that I do theoretical physics. Theoretical physics is a human endeavor, one of the higher developments of human beings—and this perpetual desire to prove that people who do it are human by showing that they do other things that a few other humans do (like playing bongo drums) is insulting to me.

I am human enough to tel you to go to hel .

The Explorers and the Tourists

“When you have learned what an explanation real y is,”

Feynman had said, “you can then go on to more subtle questions.”

Creeping philosophy. What is an explanation? Science and scientists had commandeered the practice of explanation, but the theory they left mainly to philosophers.

The why seemed to fal in their domain. “With this question philosophy began and with this question it wil end,” Martin Heidegger had recently said, “provided that it ends in greatness and not in an impotent decline.” Feynman, who believed that the impotent decline was wel under way in the academies that supported philosophers, realized that he had had to develop a view of what constituted explanation, what legitimized explanation, and which phenomena did