Genius (68 page)
Authors: James Gleick
He was frightened. In the years after the prize he felt uncreative. His Caltech colleague David Goodstein traveled with him to the University of Chicago when he went to address the undergraduates there early in 1967. Goodstein thought he seemed depressed and worried. When Goodstein came down to breakfast at the faculty club, he found Feynman already there, talking with someone who Goodstein gradually realized was the codiscoverer of DNA, James Watson. Watson gave Feynman a manuscript tentatively titled
Honest Jim
. It was a tame memoir by later standards, but when it was published—under a different title,
The Double Helix
—it caused an enormous popular stir. With a candor that shocked many of Watson’s colleagues, it portrayed the ambition, the competitiveness, the blunders, the miscommunications, and the raw excitement of real scientists. Feynman read it in his room at the Chicago faculty club, skipping the cocktail party in his honor, and found himself moved. Later he wrote Watson:
Don’t let anybody criticize that book who hasn’t read it through to the end. Its apparent minor faults and petty gossipy incidents fall into place as deeply meaningful… . The people who say “that is not how science is done” are wrong… . When you describe what went on in
your
head as the truth haltingly staggers upon you and passes on, finally fully recognized, you are describing how science
is
done. I know, for I have had the same beautiful and frightening experience.
Late that night in Chicago he startled Goodstein by pressing the book into his hands and telling him he had to read it. Goodstein said he would look forward to it. No, Feynman said. You have to read it
now
. So Goodstein did, turning pages until dawn as Feynman paced nearby or sat and doodled on a sheet of paper. At one point Goodstein remarked, “You know, it’s amazing that Watson made this great discovery even though he was so out of touch with what everyone in his field was doing.”
Feynman held up the paper he had been writing on. Amid scribbling and embellishments he had inscribed one word:
DISREGARD
.
“That’s what I’ve forgotten,” he said.
In 1983, looking back on the evolution of particle physics since the now-historic Shelter Island conference, Murray Gell-Mann said, uncontroversially, that he and his colleagues had developed a theory that “works.” He summed it up in one intricately crafted sentence (rather more refined than “All things are made of atoms …”):
It is of course a Yang-Mills theory, based on color
SU
(3) and electroweak
SU
(2)
U
(1), with three families of spin ½ leptons and quarks, their antiparticles, and some spinless Higgs bosons in doublets and antidoublets of the weak isotopic spin to break the electroweak group down to
U
1 of electromagnetism.
His listeners recognized vintage Gell-Mann, from the “of course” onward. For aficionados there was a poetry in the jargon, much of which Gell-Mann had invented personally. He loved language more than ever. As always, during the next hour he punctuated his physics with a stream of abstruse and punning nomenclatural asides: “By the way, some people have called the higglet by another name [holds up a box of Axion laundry presoak], in which case it’s extremely easy to discover in any supermarket”; “… many physicists—Dimopoulos, Nanopoulos, and Iliopoulos, and for the benefit of my French friends I add Rastopopoulos”; “… O’Raifertaigh. (His name, by the way, is written in a simplified manner; the ‘f’ should really be ‘thbh’)”; and so on.
Some people found his style irritating—among them, those whose names he tried to correct—but that was a minor detail. Gell-Mann, more than any other physicist of the sixties and seventies, defined the mainstream of the physics that Feynman had reminded himself to
disregard
. In so many ways these two scientific icons had come to seem like polar opposites—the Adolphe Menjou and Walter Matthau of theoretical physics. Gell-Mann loved to know things’ names and to pronounce them correctly—so correctly that Feynman would misunderstand, or pretend to misunderstand, when Gell-Mann uttered so simple a name as
Montreal
. Gell-Mann’s conversational partners often suspected that the obscure pronunciations and cultural allusions were designed to place them at a disadvantage. Feynman pronounced
potpourri
“pot-por-eye” and
interesting
as if it had four syllables, and he despised nomenclature of all kinds. Gell-Mann was an enthusiastic and accomplished bird-watcher; the moral of one of Feynman’s classic stories about his father was that the name of a bird did not matter, and the point was hardly lost on Gell-Mann.
Physicists kept finding new ways to describe the contrast between them. Murray makes sure you know what an extraordinary person he is, they would say, while Dick is not a person at all but a more advanced life form pretending to be human to spare your feelings. Murray was interested in almost everything—but not the branches of science outside high-energy physics; he was openly contemptuous of those. Dick considered all science to be his territory—his responsibility—but remained brashly ignorant of everything else. Some well-known physicists resented Feynman for his cherished irresponsibility—it was, after all, irresponsibility to his academic colleagues. A larger number disliked Gell-Mann for his arrogance and his sharp tongue.
There was always more. Dick wore shirtsleeves, Murray wore tweed. Murray ate at the Atheneum, the faculty club, while Dick ate at “the Greasy,” the cafeteria. (This was only half true. Either man could be found at either place on occasion, although Feynman, when the Atheneum still required ties and jackets, would show up in shirtsleeves and demand the most garish and ill-fitting of the spare items kept on hand for emergencies.) Feynman talked with his hands—with his whole body, in fact—whereas Gell-Mann, as the physicist and science writer Michael Riordan observed, “sits calmly behind his desk in a plush blue swivel chair, hands folded, never once lifting them to make a gesture… . Information is exchanged by words and numbers, not by hands or pictures.” Riordan added:
Their personal styles spill over into their theoretical work, too. Gell-Mann insists on mathematical rigor in all his work, often at the expense of comprehensibility… . Where Gell-Mann disdains vague, heuristic models that might only point the way toward a true solution, Feynman revels in them. He believes that a certain amount of imprecision and ambiguity is
essential
to communication.
Yet they were not so different in their approach to physics. Those who knew them best as physicists felt that Gell-Mann was no more likely than Feynman to hide behind formalism or to use mathematics as a stand-in for physical understanding. Those who considered him pretentious about language and cultural trivia felt nonetheless that when it came to physics he was as honest and direct as Feynman. Over a long career Gell-Mann made his vision not only comprehensible but irresistible. Both men were relentless on the trail of a new idea, able to concentrate absolutely, willing to try anything.
Both men, it seemed to a few perceptive colleagues, presented a mask to the world. “Murray’s mask was a man of great culture,” Sidney Coleman said. “Dick’s mask was Mr. Natural—just a little boy from the country that could see through things the city slickers can’t.” Both men filled their masks until reality and artifice became impossible to pry apart.
Gell-Mann, as naturalist, collector, and categorizer, was well primed to interpret the exploding particle universe of the 1960s. New technology in the accelerators—liquid hydrogen bubble chambers and computers for automating the analysis of collision tracks—seemed to have spilled open a bulky canvas bag from which nearly a hundred distinct particles had now tumbled forth. Gell-Mann and, independently, an Israeli theorist, Yuval Ne’eman, found a way in 1961 to organize the various symmetries of spins and strangeness into a single scheme. It was a group, in the mathematicians’ sense of the word, known as
SU
(3), though Gell-Mann quickly and puckishly dubbed it the Eightfold Way. It was like an intricate translucent object which, when held to the light, would reveal families of eight or ten or possibly twenty-seven particles—and they would be different, though overlapping, families, depending on which way one chose to view it. The Eightfold Way was a new periodic table—the previous century’s triumph in classifying and thus exposing the hidden regularities in a similar number of disparate “elements.” But it was also a more dynamic object. The operations of group theory were like special shuffles of a deck of cards or the twists of a Rubik’s cube.
Much of
SU
(3)’s power came from the way it embodied a concept increasingly central to the high-energy theorist’s way of working: the concept of inexact symmetry, almost symmetry, near symmetry, or—the term that won out—
broken symmetry
. The particle world was full of near misses in its symmetries, a dangerous problem, since it seemed to permit an ad hoc escape route whenever an expected relationship failed to match.
Broken symmetry
implied a process, a change in status. A symmetry in water is broken when it freezes, for now the system does not look the same from every direction. A magnet embodies symmetry breaking, since it has made a kind of choice of orientation. Many of the broken symmetries of particle physics came to seem like choices the universe made when it condensed from a hot chaos into cooler matter, spiked as it is with so many hard-edged, asymmetrical contingencies.
Once again Gell-Mann trusted his scheme enough to predict, as a consequence of broken symmetry, a specific hitherto-unseen particle. This, the omega minus, duly turned up in 1964—a thirty-three-experimenter team had to canvass more than one million feet of photographs—and Gell-Mann’s Nobel Prize followed five years later.
His next, most famous invention came in an effort to add explanatory understanding to the descriptive success of the Eightfold Way.
SU
(3) should have had, along with its various eight-member and ten-member and other families, a most-basic three-member family. This seemed a strange omission. Yet the rules of the group would have required this threesome to carry fractional electric charges: ? and – ?. Since no particle had ever turned up with anything but unit charge, this seemed implausible even by modern standards. Nevertheless, in 1963 Gell-Mann and, independently, a younger Caltech theorist, George Zweig, proposed it anyway. Zweig called his particles
aces
. Gell-Mann won the linguistic battle once again: his choice, a croaking nonsense word, was
quark
. (After the fact, he was able to tack on a literary antecedent when he found the phrase “Three quarks for Muster Mark” in
Finnegans Wake
, but the physicist’s quark was pronounced from the beginning to rhyme with “cork.”)
It took years for Gell-Mann and other theorists to generate all the contrivances needed to make quarks work. One contrivance was a new property called
color
—purely artificial, with no connection to everyday color. Another was
flavor
: Gell-Mann decided that the flavors of quarks would be called
up
,
down
, and
strange
. There had to be antiquarks and anticolors. A new mediating particle called the
gluon
would have to carry color from one quark to another. All this encouraged skepticism among physicists. Julian Schwinger wrote that he supposed such particles would be detected by “their palpitant piping, chirrup, croak, and quark.” Zweig, far more vulnerable than Gell-Mann, felt that his career was damaged. The quark theorists had to wrestle with the fact that their particles never appeared anywhere, though people did begin a dedicated search in particle accelerators and supposed cosmic-ray deposits in undersea mud.
There was a reality problem, distinctly more intense than the problem posed by more familiar entities such as electrons. Zweig had a concrete, dynamical view of quarks—too mechanistic for a community that had learned as far back as Heisenberg to pay attention only to
observables
. Gell-Mann’s comment to Zweig was, “The concrete quark model—that’s for blockheads.” Gell-Mann was wary of the philosophical as well as the sociological problem created by any assertion one way or the other about quarks being real. For him quarks were at first a way of making a simple toy field theory: he would investigate the theory’s properties, abstract the appropriate general principles, and then throw away the theory. “It is fun to speculate about the way quarks would behave if they were physical particles of finite mass (instead of purely mathematical entities as they would be in the limit of infinite mass),” he wrote.
As if
they were physical particles; then again,
as if
they were conveniences of mathematics. He encouraged “a search for stable quarks”—but added with one more twist that it “would help reassure us of the nonexistence of real quarks.” His initial caveats were quoted by commentators again and again in the years that followed. One physicist’s typically uncharitable interpretation: “I always considered that to be a coded message. It seemed to say, ‘If quarks are not found, remember I never said they would be; if they are found, remember I thought of them first.’” For Gell-Mann this became a permanent source of bitterness.
Feynman, meanwhile, had disregarded so much of the decade’s high-energy physics that he had to make a long-term project of catching up. He tried to pay more attention to experimental data than to the methods and language of theorists. He tried, as always, to read papers only until he understood the issue and then to work out the problem for himself. “I’ve always taken an attitude that I have only to explain the regularities of nature—I don’t have to explain the methods of my friends,” he told a historian during these years. He did manage to avoid some passing fashions. Still, he was turning back to a community after having drifted outside, and he had to learn its shared methods after all. It was no longer possible to approach these increasingly formidable, specialized problems as an outsider. He had stopped teaching high-energy physics; in the late sixties he began again. At first his syllabus contained no quarks.
