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February 17, 1988

Richard Feynman Dead at 69; Leading Theoretical Physicist

By JAMES GLEICK

Richard P. Feynman, arguably the most brilliant, iconoclastic and influential of the postwar generation of theoretical physicists, died Monday night in Los Angeles of abdominal cancer. He was 69 years old.

An architect of quantum theories, a brash young group leader on the atomic bomb project and the inventor of the indispensible ''Feynman diagrams'' of particle behavior, he took half-made conceptions of matter and energy in the 1940's and shaped them into tools that ordinary physicists could understand and calculate with.

Although his handiwork permeates the foundations of modern science, millions of Americans heard his name for the first time in 1986, when he brought an inquisitive and caustic presence to the Presidential commission investigating the explosion of the space shuttle Challenger.

Early on, he stunned a Washington hearing room by calling for ice water, plunking in a piece of the critical O ring seal from the rocket booster and then pinching it with a small clamp. It was a turning point in the investigation - a simple experiment, taking half a minute and no money, that perfectly demonstrated both the vulnerability of the seal and the absolute confidence of the experimenter.

To physicists who knew Dr. Feynman as a colleague or as a teacher, neither his faith in nature's simplicity nor his impatience with mediocrity came as a surprise.

''He was the most original mind of his generation,'' said Freeman Dyson of the Institute for Advanced Study in Princeton, N.J.

A Genius and a 'Magician'

''He's the most creative theoretical physicist of his time and a true genius,'' said Sidney D. Drell, former president of the American Physical Society. ''He has touched with his unique creativity just about every field of physics.''

Hans Bethe of Cornell University, paraphrasing the mathematician Mark Kac, said there were two kinds of geniuses. The ordinary kind does great things but lets other scientists feel that they could do the same if only they worked hard enough. The other kind performs magic.

''A magician does things that nobody else could ever do and that seem completely unexpected,'' Dr. Bethe said, ''and that's Feynman.''

Dr. Feynman shared the Nobel Prize for work he completed in his 20's, remaking the theory of quantum electrodynamics, which governs every physical and chemical process except those embracing gravitation and radioactivity. He could have won it again, many believed, for work with Murray Gell-Mann that created a theory for weak interactions, describing such phenomena as the emission of electrons from radioactive nuclei.

Dr. Feynman himself is said to have liked the later work better. ''I won the prize for shoving a great problem under the carpet,'' he said disingenuously, ''but in this case there was a moment when I knew how nature worked - it had elegance and beauty.''

An Educator and Author

He also provided a mathematical theory that explained the strange behavior of liquid helium at temperatures a breath away from absolute zero. And later, exploring the behavior of electrons in high-energy collisions at the Stanford Linear Accelerator Center, he provided an explanation that proved to be the most illuminating and, characteristically, the simplest.

These were his four greatest scientific achievements, but he also left a deep mark on modern physics as an educator and an author.

At Cornell University in the 1940's and then in a long career at the California Institute of Technology, Dr. Feynman developed a lecture style that kept him at the center of attention, the impossible combination of theoretical physicist and circus barker, all body motion and sound effects.

One series of lectures was collected and published in a set that remains an indispensible physics text, ''The Feynman Lectures on Physics''; another series became an eloquent book, ''The Character of Physical Law,'' and yet another became ''QED: The Strange Theory of Light and Matter.'' His 1985 memoirs, ''Surely You're Joking, Mr. Feynman,'' became a surprising best-seller.

Relentless Pursuit of Knowledge

Above all, in and out of science, Dr. Feynman was a curious character -his phrase, and the double meaning was intentional. He was never content with what he knew or what other people knew. He taught himself how to fix radios, pick locks, draw nudes, speak Portuguese, play the bongos and decipher Mayan hieroglyphics. He pursued knowledge without prejudice, studying the tracking ability of ants in his bathtub and learning enough biology to study the mutation of bacteriophages.

In his youth he experimented for months with trying to observe his unraveling stream of consciousness at the point of falling asleep; in his middle age he experimented with inducing out-of-body hallucinations in a sensory-deprivation tank.

But Dr. Feynman was no mystic, and he despised all kinds of fake learning, particularly pseudo-science. In that category he placed a good part of modern psychology, calling it ''cargo cult science.''

Certain Pacific islanders, he explained, wanted the cargo planes to keep returning after World War II was over. So they made runways, stationed a man with wooden headphones and bamboo for antennas, lighted some fires and waited for the planes to land.

It is the same, he said, with cargo cult scientists. ''They follow all the apparent precepts and forms of scientific investigation, but they're missing something essential because the planes don't land.''

For Dr. Feynman, the planes almost always landed.

A Key Role At Los Alamos

Richard Phillips Feynman was born on May 11, 1918, in Far Rockaway, Queens. His meditative approach to radio repair, a hobby he took up when he was 11 or 12 years old, gave him a neighborhood reputation as the boy who could fix radios by thinking.

After graduating from Far Rockaway High School in 1935, he went on to the Massachusetts Institute of Technology and then to Princeton University, where he received his doctorate in 1942. By then he had been recruited for the Manhattan Project to build an atomic bomb at Los Alamos, N.M.

Stories from the time, including Dr. Feynman's own, give the impression that he spent most of his time thinking up ways to infuriate the military censors and security officers. He and his first wife exchanged letters they had cut into pieces of a jigsaw puzzle.

Dr. Feynman also devoted himself to cracking the combination safes that had been installed to protect the bomb secrets - the plutonium production schedules, the construction dimensions, the neutron radiation data, ''the whole schmeer,'' as he wrote later. When the responsible officers turned their backs he would unlock the steel doors and leave notes with messages like, ''I borrowed document No. LA4312 - Feynman the safecracker.''

Primitive Computer Effort

But Dr. Feynman's real role was deeper than he liked to suggest in his anecdotes for public consumption. Dr. Bethe, the leader of the theoretical division, recognized him as the most ingenious member of his team.

The two men devised a formula for predicting the energy yield of a nuclear weapon - a formula that remains classified, Dr. Bethe said. Dr. Feynman also took charge of the project's primitive computing effort, using rows of new machines to try to manage the vast amount of numerical calculating required.

Dr. Feynman's years with the Manhattan Project brought the brazen young scientist into close contact with the world's greatest physicists and mathematicians. He would attend meetings in Edward Teller's office, furiously exchanging ideas with Enrico Fermi and John von Neumann, manipulating his desk calculator at top speed while von Neumann worked the same problems in his head.

In the end, Dr. Feynman said he was possibly the only man confident enough or reckless enough to watch the first atomic bomb test with the naked eye, protected only by a truck windshield. He decided that the only harm could come from ultraviolet rays and that the window glass would screen those.

Only afterward, sitting in a New York restaurant and calculating the radius of potential bomb damage in midtown Manhattan, did he lose the euphoric feeling that drove him in the years he worked to develop the bomb.

''You see, what happened to me -what happened to the rest of us,'' he wrote, ''is we started for a good reason, then you're working very hard to accomplish something, and it's pleasure, it's excitement. And you stop thinking, you know; you just stop.''

New Approach To Physics

When World War II ended he was invited by Dr. Bethe to teach at Cornell, and Dr. Feynman accepted. Within four years he had completed the work for which he won the Nobel Prize, in quantum electrodynamics, or QED.

In a way, Dr. Feynman was born too late to discover the big mysteries. By the 1940's the two great revolutions of 20th-century physics were in full swing. Einstein's theory of relativity had transformed scientists' understanding of space and time, and quantum theory had transformed their understanding of the behavior of matter and energy in the guises of particles or waves.

Together, these revolutions had made the atomic bomb possible. Now physicists were applying them to a new framework within which to study the properties of fundamental particles and the relationship between gravity, electromagnetism and the forces that bind the atom.

A crucial part of this framework was quantum electrodynamics, a modernization of the classical understanding of electromagnetic radiation - radiation like light and radio waves - formulated in the 19th century.

A Theory Runs Into Trouble

In the domain of everyday life, electromagnetic forces are familiar and well understood. At the subatomic level, though, where they govern the interaction of electrically charged particles, the theory had run into trouble. Its predictions failed to match experiments, and as physicists tried to make calculations more accurately the discrepancies grew without limit.

Physicists struggled for more than a decade to find revisions that would make the theory work. Then, working independently, Dr. Feynman, Sin-Itero Tomonaga of Japan and Julian Schwinger of Harvard University solved the problem.

Dr. Tomonaga and Dr. Schwinger connected their work to the old theory in ways that other physicists could quickly understand. But Dr. Feynman rebuilt quantum electrodynamics from the ground up. He invented a new way of calculating that drew skepticism at first.

''He tried to rediscover the whole of physics by himself,'' said Dr. Dyson, who knew Dr. Feynman well at Cornell. ''Somewhat to his disappointment, what he discovered was in agreement with what other people had done. But he had to do it his own way, and what came out of it all was a new way of looking at things which has been enormously fruitful.''

A Shocking Technique

Dr. Feynman's approach, now in universal use by physicists, allowed calculation in areas that had been regarded as impossibly esoteric. He framed the events of physics in terms of particle interactions, abandoning the idea of waves, and he created a practical way of diagraming the interactions of particles that now bears his name.

Feynman diagrams use lines to represent the histories of particles and nodes to represent their interactions. Using symbols in a highly abstract way, it becomes possible to understand complicated events that otherwise would have taken weeks to calculate.

The resulting predictions have been verified to astonishing precision in a wide range of experiments. But the technique shocked some physicists trained in the old ways. Sometimes a Feynman diagram would produce a result that ran contrary to all intuition -for example, a positron running backwards in time.

Another central notion was equally hard to swallow: that a physicist should make calculations not by solving some overall equation, but rather by taking all the possible histories of a particle interaction and adding them together, making a sum of probabilities. As Dr. Feynman himself said, the theory often seemed absurd.

A Fruitful Collaboration

Dr. Feynman liked to speak of ''the laws,'' meaning the laws of nature, in a particularly clean and classical sense. ''If the only laws that you find are those which you have just finished observing, then you can never make any predictions,'' he said.

''Of course, this means that science is uncertain - the moment that you make a proposition about a region of experience that you have not directly seen, then you must be uncertain,'' he continued. ''But we always must make statements about the regions that we have not seen, or the whole business is no use.''

In 1950 Dr. Feynman moved to the California Institute of Technology in Pasadena, and he spent the rest of his life there. He began a fruitful collaboration with Caltech's other star, Murray Gell-Mann, a brilliant physicist 11 years his junior, and their collaboration often seemed like a rivalry.

''Dick is always calling up to see whether Murray is working,'' Dr. Gell-Mann's wife, Margaret, once said. ''If I say he's in the garden Dick is happy for the rest of the day. But if I tell him Murray is doing physics, then Dick gets nervous and immediately wants to come over.''

Together they discovered new laws. They investigated the weak force, which plays a central role in the binding of the atomic nucleus and governs the emission of fast-moving electrons in the beta-decay of radioactive substances.

Counter to the Evidence

The problem had given rise to theoretical confusion. The Caltech physicists cut through the difficulties with an approach that explained weak interactions in terms of such particle properties as spin. It proved to apply universally, but when they first prepared it for presentation they had a problem: the theory ran counter to specific experimental evidence.

''It seemed that their work contradicted an experiment,'' Dr. Bethe said, ''but they had the courage to say, 'This theory is so simple, so straightforward and beautiful, it must be right.' And it turned out to be right.'' The errors were in the experiment.

Dr. Feynman conceptualized problems in a particularly mathematical way, always trying to cull the essence, the laws, from the physical details. Mathematics was nature's own language, he felt.

''If you want to learn about nature, to appreciate nature, it is necessary to understand the language that she speaks in,'' he said. ''She offers her information only in one form; we are not so unhumble as to demand that she change before we pay any attention.''

In the 1950's he used a mathematical approach to make a theory for liquid helium, which at very low temperatures becomes superfluid, behaving as if it had no viscosity at all. Dr. Feynman's approach gave physicists a way of consistently understanding a whole range of properties of liquid helium. And more than a decade later, he put forward an equally illuminating theory for the scattering of electrons at high energy.

The Challenger Investigation

With rare exceptions, Dr. Feynman avoided the usual kinds of committees that prominent scientists serve on. In the 1960's he agreed to serve briefly on the California State Curriculum Commission and evaluate high school science textbooks, a memorable experience for the commission, since he found the books consistently ''lousy,'' ''false'' and ''useless.'' And when the space shuttle Challenger exploded shortly after it was launched on Jan. 28, 1986, Dr. Feynman joined the Presidential commission investigating the disaster. His co-commissioners soon found that it was hard to keep track of him.

Sometimes, with the commission meeting in full session, he would be missing. Later it would turn out that he had been conducting a private investigation, prowling around Cape Canaveral, Fla., questioning engineers and looking at the rocket boosters in storage.

That did not sit well with the chairman, William P. Rogers, who wanted an ''orderly investigation.'' Nor did Mr. Rogers like Dr. Feynman's habit of heading for the television cameras to share his findings.

At the hearings themselves, his hair often disheveled, Dr. Feynman ambushed witnesses from the National Aeronautics and Space Administration with aggressive questioning. Then, on Feb. 11, as a piece of O ring material was being passed from commissioner to commissioner, he quietly asked for ice water.

The rubbery O ring provided the critical seal in the rocket booster, and was designed to block the escape of hot gas from the joint connecting the individual rocket segments. Its ability to perform when cold was coming under sharp scrutiny.

As Dr. Feynman expected, when he cooled the rubbery material and squeezed it with a clamp, it failed to spring back into shape. Mr. Rogers saw what was coming, and a few minutes later, at the lunch break, he turned to the astronaut Neil Armstrong and said, ''Feynman is becoming a real pain.''

Material Found Vulnerable

After the break, Dr. Feynman brought the crowded hearing room to dead silence by addressing Lawrence B. Mulloy, the former chief of the solid rocket booster program: ''I took this stuff that I got out of your seal and I put it in ice water, and I discovered that when you put some pressure on it for a while and then undo it, it doesn't stretch back. It stays the same dimension. In other words, for a few seconds at least and more seconds than that, there is no resilience in this particular material when it is at a temperature of 32 degrees.''

Dr. Feynman and others concluded that if the space agency had conducted the same experiment and acted on the results, the disaster could have been avoided. When the commission finished its work, Mr. Rogers was barely able to prevail upon Dr. Feynman not to dissent from the report.

But he held a separate news conference to deliver a harsh and independent verdict: that NASA had ''exaggerated the reliability of the space shuttle to the point of fantasy.''

Even then, Dr. Feynman had begun a struggle with the cancer that killed him Monday.

Dr. Feynman's first wife, whom he married in 1941, died five years later while he was in Los Alamos. After a second marriage ended in divorce, he married Gweneth Howarth. She and their two children, Carl and Michelle, and his sister, Joan Feynman, survive him.

'I Can Live With Doubt'

The physics that he leaves behind is more difficult, more abstract and more distant from the world of everyday human experience than any science of the past. To those qualities, he contributed as much as anyone of his time.

Physicists like Einstein had to struggle to reconcile their ordinary intuitions with the evidence of their equations. Dr. Feynman happily gave up the struggle. He and the physicists of his generation made peace with a way of describing nature that only explained how, not why.

Much of what he accomplished he would admit to not understanding. ''I can live with doubt and uncertainty,'' he once said. ''I think it's much more interesting to live not knowing than to have answers which might be wrong.

''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, so far as I can tell,'' he added. ''It doesn't frighten me.''

Copyright 1997 The New York Times Company (used without permission, but with respect)