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

Mil ikan’s error exerted a psychological pul , like a distant magnet forcing their observations off center. If a Caltech experimenter told Feynman about a result reached after a

complex process of correcting data, Feynman was sure to ask how the experimenter had decided when to stop correcting, and whether that decision had been made before the experimenter could see what effect it would have on the outcome. It was al too easy to fal into the trap of correcting until the answer looked right. To avoid it required an intimate acquaintanceship with the rules of the scientist’s game. It also required not just honesty, but a sense that honesty required exertion.

As the particle era unfolded, however, it made other demands of top theorists—whose ranks, meanwhile, were expanding. They had to demonstrate new kinds of flair in sorting through the relations between particles. They competed to invent abstract concepts to help organize the information arriving from accelerators. A new quantum number like isotopic spin—a quantity that seemed to be conserved through many kinds of interactions—implied new incarnations of symmetry. This notion increasingly dominated the physicists’ discourse. Symmetry for physicists was not far removed from symmetry for children with paper and scissors: the idea that something remains the same when something else changes. Mirror symmetry is the sameness that remains after a reflection of left and right. Rotational symmetry is the sameness that remains when a system turns on an axis. Isotopic spin symmetry, as it happened, was the sameness that existed between the two components of the nucleus, the proton and the neutron, two particles whose relationship had been oddly close, one carrying charge and the other neutral, their masses nearly but not exactly identical. The new way to understand these particles was this: They were two states of a single entity, now cal ed a nucleon. They differed only in their isotopic spin. One was “up,” the other “down.”

Theorists of the new generation had not only to master the quantum electrodynamics set forth by Feynman and Dyson. They also had to arm themselves with a rococo

repertoire of methods suited to the new territory. Physicists had long utilized exotic variations of the idea of space —

imaginary spaces in which the axes might represent quantities other than physical distance. “Momentum space,”

for example, al owed them to plot and to visualize a particle’s momentum as though it were merely another spatial variable. One grew comfortable with such spaces, and now they were multiplying. Isotopic spin space became essential to understanding the strong forces acting on nucleons.

Other concepts, too, had to become second nature.

Symmetries suggested that various particles must come in families: pairs, or triplets, or (as physicists now said) multiplets. Physicists experimented with what they cal ed

“selection rules”—rules about what must or must not happen in particle col isions on account of the conservation of quantities like charge. A physicist Feynman’s age, Abraham Pais, guessed at a rule cal ed “associated production”—certain col isions must produce new particles in groups, preserving some putative new quantum number, the nature of which was unknown. Feynman had had a similar idea in Brazil but had not liked it enough to pursue it diligently. For a few years associated production became an important catchphrase. Experimenters looked for examples or counterexamples. In the longer term its main contribution to physics was that its popularity rankled a younger theorist, Murray Gel -Mann. He thought Pais was wrong, and he was jealous.

Murray

At fourteen he had been declared “Most Studious” and

“wonder boy” by his classmates at Columbia Grammar, a private school on the Upper West Side of New York, and that was the last they saw of him, for he was already a

senior, and he started at Yale that fal . Gel -Mann’s surname was subtly difficult to pronounce. It was wrong to unstress the second syl able, as if the name were Gelman, although Murray’s older brother, Benedict, had chosen that simpler spel ing. Many people leaned the other way, toward a pedantic, European style of pronunciation, the accent on the second syl able and the a broad: gel -MAHN. This, too, was wrong. Later, when he had secretaries, they sometimes upbraided malefactors: “He’s not German, you know.” Of course the g was hard, despite the unconscious tug of the soft g in the word gel . Natives of New York and other regions that distinguish between the a ’s of man and mat suspected rightly that the second, flatter a must be better for Gel -Mann. It was safest to stress the two syl ables almost equal y. By then anyone who knew anything about Gel -Mann knew that his own pronunciation of names in any language was impeccable. Supposedly he would lecture visitors from Strasbourg or Pago Pago about the niceties of their own Alsatian or Samoan dialects. He was so insistent about differentiating the pronunciations of Colombia and Columbia that col eagues suspected him of straining to bring references to the country into conversations about the university. From the beginning most physicists simply referred to him as Murray. There was never any doubt which Murray they meant. Feynman, preparing for a cameo performance as a tribal chieftain in a Caltech production of South Pacific , taught himself a few words of Samoan and then resignedly told a friend, “The only person who wil know I’m pronouncing this wrong is Murray.”

Gel -Mann attended Columbia Grammar on ful scholarship. His father, born in Austria, had learned to speak a perfectly unaccented English and so, in the early 1920s, decided to start a language school for immigrants. It was the closest to success that he came, as his son saw it.

The school moved several times—once, as Murray recal ed, because his mother was afraid that his brother would catch whooping cough from someone in the building

—and went out of business a few years later. It was his brother, nine years older and so adored by his parents, who taught him to read and to take pleasure in language, science, and art. Benedict was a bird-watcher and nature lover before nature became a practical field of interest; dropping out of col ege at the height of the Depression, he stunned his parents and left a complicated impression on his younger brother.

Murray did not find his way immediately to physics, talented as he was in so many subjects. When he applied to the Ivy League graduate schools, he was widely disappointed: Yale would take him only in mathematics, Harvard would take him only if he paid ful fare, and Princeton would not take him at al . So he made a half-hearted application to MIT and heard directly back from Victor Weisskopf, whom he had not heard of. Gel -Mann decided to accept Weisskopf’s offer, though grudgingly.

MIT seemed so lumpen. The joke he told ever after was that the alternatives did not commute: he could try MIT first and suicide second, whereas the other ordering would not work.

He reached MIT in 1948, close to his nineteenth birthday, just in time to watch the exploding competition in quantum electrodynamics from the vantage point of an office near Weisskopf’s. When Weisskopf advised him that the future belonged to Feynman, he studied the available preprints.

Feynman’s struck him as a cuckoo private language, though correct; Schwinger’s version struck him as hol ow and pompous; Dyson’s as crude and sloppy. He was already inclined toward scabrous assessments of his famous fel ow physicists, though for now he kept them mostly private.

His own work was not quite living up to his severe expectations, though he was final y beginning to impress