Genius (76 page)

Whether or not nature has an ultimate, simple, unified, beautiful form is an open question, and I don’t want to say either way.

In the 1980s a mathematically powerful and experimentally untestable attempt at unification emerged in the form of string theory, using stringlike entities wrapped through many dimensions as their fundamental objects. The extra dimensions are supposed to fold themselves out of the way in a kind of symmetry breaking given the name
compactification
. String theory relies on Feynman’s sum-over-histories method as an essential underlying principle; the theory views particle events as topological surfaces and computes probability amplitudes by summing over all possible surfaces. Feynman kept his distance, sometimes saying that perhaps he was too old to appreciate the new fashion. String theory seemed too far from experiment. He suspected that the string theorists were not trying hard enough to prove themselves wrong. In the meantime he never adopted the rhetoric of GUT’s. It made him uncomfortable. He retreated into the stance that he himself merely solved problems as they came along.

When a historian of particle physics pressed him on the question of unification in his Caltech office, he resisted. “Your career spans the period of the construction of the standard model,” the interviewer said.

“‘The standard model,’” Feynman repeated dubiously.

“
SU
(1) ×
SU
(2) ×
U
(1). From renormalization to quantum electrodynamics to now?”

“The standard model, standard model,” Feynman said. “The standard model—is that the one that says that we have electrodynamics, we have weak interaction, and we have strong interaction? Okay. Yes.”

The interviewer said, “That was quite an achievement, putting them together.”

“They’re not put together.”

“Linked together in a single theoretical package?”

“No.”

The interviewer was having trouble getting his question onto the table. “What do you call
SU
(×3)
SU
(2)×
U
(1)?”

“Three theories,” Feynman said. “Strong interactions, weak interactions, and electromagnetic… . The theories are linked because they seem to have similar characteristics… . Where does it go together? Only if you add some stuff that we don’t know. There isn’t any theory today that has
SU
(3) ×
SU
(2) ×
U
(1)—whatever the hell it is—that we know is right, that has any experimental check… . Now, these guys are all trying to put all this together. They’re
trying
to. But they haven’t. Okay?”

Particle physicists were his community. They were the elite who revered him, who passed along his legend, who lent him so much of his prestige. He rarely dissented publicly from their standard dogma. For the past two decades, he had worked on their problems: try though he might to
disregard
, in the end he had accepted their agenda.

“So we aren’t any closer to unification than we were in Einstein’s time?” the historian asked.

Feynman grew angry. “It’s a crazy question! … We’re certainly closer. We know more. And if there’s a finite amount to be known, we obviously must be closer to having the knowledge, okay? I don’t know how to make this into a sensible question… . It’s all so stupid. All these interviews are always so damned useless.”

He rose from his desk and walked out the door and down the corridor, drumming his knuckles along the wall. The writer heard him shout, just before he disappeared: “It’s goddamned useless to talk about these things! It’s a complete waste of time! The history of these things is nonsense! You’re trying to make something difficult and complicated out of something that’s simple and beautiful.”

Across the hall Murray Gell-Mann looked out of his office. “I see you’ve met Dick,” he said.

Feynman had always set high standards for
fundamental
work, although he meant something broader by the word than many particle physicists did. Liquid helium and other solid-state problems had seemed to him as fundamental as the smallest-scale particle interactions. He believed that fundamentalness, like beauty or intelligence, was a multidimensional quality. He had tried to understand turbulence and quantum gravity. Throughout his career he had suffered painful periods of malaise, when he could not find a suitable problem. In later years he and his colleagues had seen their crowded field thin: bright young students, looking for fundamental issues on their own terms, often turned to biology, computation, or the new study of chaos and complexity. When his son, Carl, ended his flirtation with philosophy and took up computer science, Feynman, too, looked again at the field he had helped pioneer at Los Alamos. He joined two Caltech authorities on computation, John Hopfield and Carver Mead, in constructing a course on issues from brain analogues and pattern recognition to error correction and uncomputability. For several summers he worked with the founders of Thinking Machines Corporation, near MIT, creating a radical approach to parallel processing; he served as a high-class technician, applying differential equations to the circuit diagrams, and as an occasional wise man among the young entrepreneurs (“Forget all that ‘local minima’ stuff—just say there’s a bubble caught in the crystal and you have to shake it out”). And he began to produce maverick research at the intersection of computing and physics: on how small computers could be; on entropy and the uncertainty principle in computing; on simulating quantum physics and probabilistic behavior; and on the possibility of building a quantum-mechanical computer, with packets of spin waves roaming ballistically back and forth through the logic gates.

His own community had largely left behind questions with the spirit that first drove him toward physics. An intellectual distance had opened between the subatomic particle universe and the realm of ordinary phenomena—the magic that nature reveals to children. In
The Feynman Lectures
he spoke allegorically of the beauty of a rainbow. Imagine a world in which scientists could not see a rainbow: they might discover it, but could they sense its beauty? The essence of a thing does not always lie in the microscopic details. He supposed that the blind scientists learned that, in some weathers, the intensity of radiation plotted against wavelength at a certain direction in the sky would show a bump, and the bump would shift from one wavelength to another as the angle of the instrument shifted. “Then one day,” he said, “the physical review of the blind men might publish a technical article with the title ‘The Intensity of Radiation as a Function of Angle under Certain Conditions of the Weather.’” Feynman had no quarrel with
beauty
—our human illusion, our projection of sentiment onto a reality of radiation phenomena.

“We are all reductionists today,” said Steven Weinberg—meaning that we seek the deepest explanatory principles in the elementary particles that underlie ordinary matter. He spoke for many particle physicists but not for Feynman. Understanding the principles at the lowest level of the hierarchy—the smallest length-scales—is not the same as understanding nature. So much lies outside the accelerators’ domain, even if it is in some sense
reducible
to elementary particles. Chaotic turbulence; the large-scale structures that emerge in complex systems; life itself: Feynman spoke of “the infinite variety and novelty of phenomena that can be generated from such simple principles”—phenomena that are “in the equations; we just haven’t found the way to get them out.”

The test of science is its ability to predict. Had you never visited the earth, could you predict the thunderstorms, the volcanoes, the ocean waves, the auroras, and the colorful sunset? …

The next great era of awakening of human intellect may well produce a method of understanding the qualitative content of equations. Today we cannot. Today we cannot see that the water-flow equations contain such things as the barber pole structure of turbulence that one sees between rotating cylinders. Today we cannot see whether Schrödinger’s equation contains frogs, musical composers, or morality—or whether it does not.

Physicists’ models are like maps: never final, never complete until they grow as large and complex as the reality they represent. Einstein compared physics to the conception a person might assemble of the interior mechanism of a closed watch: he might build a plausible model to account for the rhythmic ticking, the sweep of the hands, but he could never be certain. “He may also believe in the existence of the ideal limit of knowledge and that it is approached by the human mind,” Einstein said. “He may call this ideal limit the objective truth.” It was a simpler time. In Feynman’s era, knowledge advanced, but the ideal of objective truth receded deeper into the haze beyond the vision of science. Quantum theory had left an impossible question dangling in the air. One physicist chose to answer it by quoting Feynman, “one of the great philosophers of our time, whose view of the matter I have taken the liberty of quoting in the form of the poetry it surely is”:

We have always had a great deal of difficulty
understanding the world view
that quantum mechanics represents.

At least I do,
because I’m an old enough man
that I haven’t got to the point
that this stuff is obvious to me.

Okay, I still get nervous with it….
You know how it always is,
every new idea,
it takes a generation or two
until it becomes obvious
that there’s no real problem….

I cannot define the real problem,
therefore I suspect there’s no real problem,
but I’m not sure
there’s no real problem.

In October 1987 another abdominal tumor appeared, and his doctors made one last attempt to stall his cancer surgically. When the
Los Angeles Times
sent him an advance copy of his obituary, he thanked the author but said, “I have decided it is not a very good idea for a man to read it ahead of time: it takes the element of surprise out of it.” He knew he was not recovering. He was sixty-nine years old. Pain wracked one of his legs. He was exhausted. He had no appetite. In January he began awakening in the night with sweats and chills. In one corner of his dusty office blackboard he had written a pair of self-conscious mottoes: “What I cannot create I do not understand” and “Know how to solve every problem that has been solved.” Nearby was a running list under the heading, “TO LEARN” (“Bethe Ansatz Prob., 2D Hall …”). Physics changed; he talked about it once with his old Los Alamos friend Stanislaw Ulam, who had been watching a few white clouds roll against the blue New Mexico sky. Feynman seemed to read his mind: “It is really like the shape of clouds,” he said. “As one watches them they don’t seem to change, but if you look back a minute later, it is all very different.” He had not accumulated much: a hand-knitted scarf, hanging on a peg, from some students in Yugoslavia; a photograph of Michelle with her cello; some black-and-white pictures of the aurora borealis; his deep leather recliner; a sketch he had made of Dirac; a van painted with chocolate-brown Feynman diagrams. On February 3 he entered the UCLA Medical Center again.

Doctors in the intensive care unit discovered a ruptured duodenal ulcer. They administered antibiotics. But his remaining kidney had failed. One round of dialysis was performed, with little effect. Feynman refused the further dialysis that might have prolonged his life for weeks or months. He told Michelle calmly, “I’m going to die,” in a tone that said:
I
have decided. He was watched and guarded now by the three women who had loved him longest: Gweneth, Joan, and his cousin Frances Lewine, who had lived with him in the house in Far Rockaway. Morphine for pain and an oxygen tube were their last concessions to medicine. The doctors said it would take about five days. He had watched one death before—trying to be scientific, observing the descent into coma and the sporadic breathing, imagining the brain clouding as it was starved of oxygen. He had anticipated his own—toying with the release of consciousness in dark sensory-deprivation tanks, telling a friend that he had now taught people most of the good stuff he knew, and making his peace with bottomless nature:

You see, one thing is, I can live with doubt and uncertainty and not knowing. I think it’s much more interesting to live not knowing than to have answers which might be wrong. I have approximate answers and possible beliefs and different degrees of certainty about different things, but I’m not absolutely sure of anything and there are many things I don’t know anything about, such as whether it means anything to ask why we’re here… .

I don’t have to know an answer. I don’t feel frightened by not knowing things, by being lost in a mysterious universe without any purpose, which is the way it really is as far as I can tell. It doesn’t frighten me.

He drifted toward unconsciousness. His eyes dimmed. Speech became an exertion. Gweneth watched as he drew himself together, prepared a phrase, and released it: “I’d hate to die twice. It’s so boring.” After that, he tried to communicate by shifting his head or squeezing the hand that clasped his. Shortly before midnight on February 15, 1988, his body gasped for air that the oxygen tube could not provide, and his space in the world closed. An imprint remained: what he knew; how he knew.

ACKNOWLEDGMENTS

I never met Feynman. I’ve relied on the published (and semipublished) record; on his own accumulation of personal letters, notes to himself, and other documents, released to me in 1988 by Gweneth Howarth Feynman; on letters shared by other family members and friends; on his office files and other documents stored in the California Institute of Technology Archives in Pasadena; on early material collected at the Niels Bohr Library of the American Institute of Physics in New York. I obtained recently declassified notebooks and papers from the archives of Los Alamos National Laboratory. Other material came from the libraries and manuscript collections of the following institutions: the American Philosophical Society (papers of H. D. Smyth and J. A. Wheeler); the Brooklyn Historical Society; Cornell University (papers of H. A. Bethe); Far Rockaway High School; Harvard University; the Library of Congress (papers of J. R. Oppenheimer); the Massachusetts Institute of Technology; Princeton University; Rockefeller University; and the Stanford Linear Accelerator Center.