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

They reached Albuquerque, Dyson seeing for the first time the deceptively clear air and the red desert beneath stil snowy peaks. Feynman bore into town at 70 miles per hour and was immediately arrested for a rapid sequence of traffic violations. The justice of the peace announced that the fine he handed down was a personal record. They parted—Feynman to find Rose McSherry (marriage was impossible, as it happened, in part because she was determinedly Roman Catholic and he could not be), Dyson to find a bus back toward Ann Arbor and Schwinger.

Oppenheimer’s Surrender

With Bethe’s blessing Dyson moved to the Institute for Advanced Study in Princeton in the fal of 1948.

Oppenheimer had taken over as director the year before.

Dyson was eager to impress him, and he immediately sensed he was not alone. “On Wednesday Oppenheimer returns,” he wrote his parents. “The atmosphere at the Institute during these last days has been rather like the first scene in ‘Murder in the Cathedral’ with the women of Canterbury awaiting the return of their archbishop.”

He did not wait for Oppenheimer’s blessing, however, before mailing off to the Physical Review a manuscript representing a cathartic outpouring of work during the last days of the summer. He proudly told his parents that the concentration had nearly kil ed him. Inspiration came most snappily on the fifty-hour bus ride east to Princeton, he told

col eagues. (When Oppenheimer heard this he retorted with a sarcastic al usion to the lightning-from-the-blue legend of Fermat’s last theorem: “There wasn’t enough room in the margin to write down the proof.”) Dyson had found the mathematical common ground he was sure must exist. He, too, created and reshaped terminology to suit his purpose. His chief insight was to focus on a so-cal ed scattering matrix, or S matrix, a mustering of al the probabilities associated with the different routes from an initial state to a given end point. He now advertised “a unified development of the subject”—more reliable than Feynman and more usable than Schwinger. His father said that Feynman-Schwinger-Dyson reminded him of a clause in the Athanasian Creed: “There is the Father incomprehensible, and the Son incomprehensible, and the Holy Ghost incomprehensible, yet there are not three incomprehensibles but one incomprehensible.”

It occurred to Dyson that he was rushing into print with accounts of theories not yet published by their inventors and that the inventors themselves might take offense. He visited Bethe, temporarily in New York visiting Columbia, and they took a long walk in Riverside Park as the sun set over the Hudson River. Bethe warned him that there could be problems. Dyson said it was Schwinger’s and Feynman’s own fault that they had not published “any moderately intel igible account”: Schwinger, he suspected, was polishing obsessively, while Feynman simply couldn’t be bothered with paperwork. It was irresponsible. They were retarding the development of science. By publicizing

their work Dyson was performing a service to humanity, he argued. He and Bethe ended up agreeing that Feynman would not mind but that Schwinger might, and that it would be poor tactics for an ambitious young physicist to irritate Schwinger. “So the result of al this,” Dyson wrote his parents,

is that I am reversing the tactics of Mark Antony, and saying very loud at various points in my paper, “I come to praise Schwinger, not to bury him.” I only hope he won’t see through it.

Stil , he made his judgment clear. The distinctions he drew and the characterizations he set down soon became the community’s conventional wisdom: that Schwinger’s and Tomonaga’s approach was the same, while Feynman’s differed profoundly; and that Feynman’s method was original and intuitive, while Schwinger’s was formal and laborious.

Dyson wel understood that he was reaching out to an audience that wanted tools. When he showed a Schwinger formula with commutators threatening to subdivide like branches on a tree and remarked that “their evaluation gives rise to long and rather difficult analysis,” he knew that his readers would not suspect him of overstating the difficulty. Ease of use was the Feynman virtue he stressed.

To “write down the matrix elements” for a certain event, he explained, one need only take a certain set of products, replace them by sums of matrix elements from another

equation, reassemble the various terms in a certain form, and undertake a certain type of substitution. Or, he said, one could simply draw a graph.

The simplest Dyson graph.

Graph was the mathematician’s word for a network of points joined by lines. Dyson showed that there was a graph for every matrix and a matrix for every graph—the graphs provided a means of cataloging these otherwise-misplaceable arrays of probabilities. So alien did this conceit seem that Dyson left it to his readers to draw the graphs in their minds. The journal editors made room for just one figure. Dyson cal ed the solid lines, with an implicit direction, electron lines. The directionless dotted lines were photon lines. Feynman, he mentioned, had something more in mind than the mere bookkeeping of matrices: “a picture of the physical process.” For Feynman the points represented the actual creation or annihilation of particles; the lines represented paths of electrons and photons, not through a measurable real space but through the history from one quantum event to another.

from one quantum event to another.

Oppenheimer depressed Dyson with a coolness bordering on animosity. It was the last response he had expected:

a

defeatist

Oppenheimer,

a

lethargic

Oppenheimer, an Oppenheimer hostile to new ideas and unwil ing to listen. He had been in Europe, where he had summarized the present state of the theory at two international conferences. It was “Schwinger’s theory” and

“Schwinger’s program.” There were developments “the first largely, the second almost whol y, due to Schwinger.” In passing, there were “Feynman’s algorithms”—an exotical y disdainful phrase.

Dyson decided that there would be no prize for timidity and—stil in his first weeks at the institute—sent Oppenheimer by interoffice mail an aggressive manifesto.

He argued that the new quantum electrodynamics promised to be more powerful, more self-consistent, and more broadly applicable than Oppenheimer seemed to think. He did not mince words.

From Mr. F. J. Dyson.

Dear Dr. Oppenheimer:

As I disagree rather strongly with the point of view expressed in your Solvay Report (not so much with what you say as with what you do not say) …

I… . I am convinced that the Feynman theory is considerably easier to use, understand, and teach.

I . Therefore I believe that a correct theory, even if radical y different from our present ideas, wil contain more of Feynman than of Heisenberg-Pauli. …

V. I do not see any reason for supposing the Feynman method to be less applicable to meson theory than to electrodynamics… .

VI. Whatever the truth of the foregoing assertions may be, we have now a theory of nuclear fields which can be developed to the point where it can be compared with experiment, and this is a chal enge to be accepted with enthusiasm.

Enthusiasm was not immediately forthcoming, but Oppenheimer did set up a series of forums to let Dyson make his case. They became an occasion. Bethe came down from New York to listen and lend moral support. As the seminars went on, Oppenheimer was a dramatical y nerve-tightening presence. He interrupted continual y, criticizing, jabbing, pouncing on errors. To Dyson he seemed uncontrol ably nervous—always chain-smoking and fidgeting in his chair. Feynman himself was fol owing Dyson’s progress by long-distance as he continued his own work. Dyson visited him at Cornel one weekend and watched, amazed, as he rattled off two new fundamental calculations in a matter of hours. Then Feynman fired off a hasty letter: “Dear Freeman: I hope you did not go bragging about how fast I could compute the scattering of light by a potential because on looking over the calculations last night I discovered the entire effect is zero. I am sure some smart fel ow like Oppenheimer would know such a thing right off.”