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

he used himself to solve equations. Beginning with his jottings on the night train that brought him to Ithaca, he designed a new course from the bottom up.

On the first page of a cardboard notebook like the ones he had used in high school he began with first principles: Phenomena complex—laws simple— connection is math-phys—the solution of equ obtained from laws.

He was thinking about how to mold students in his own image. How did he solve problems?

Know what to leave out… . physical insight knowing what can be done by math.

He decided to give the students a blunt summary of what did and did not lie ahead.

Lots of tricks to introduce—no time for complete study or math rigor demonstration. Lots of work.

He crossed that out.

Real y introduce each subject.

But after al it would be lots of work.

Lots of work—practice. Interested in more detail, read books, see me, practice more examples. If no go

—OK we slow up. Hand in some problems so I can tel .

He would promise them important mathematical methods left out of ordinary courses, as wel as methods that were altogether new. It would be practical, not perfect, mathematics.

Specify accuracy required. Let’s go

He scanted some of the laborious traditional techniques, such as contour integration, because he had so often found

—winning bets in the process—that he could handle most such integrals directly by frontal assault. Whether he would succeed in conveying such skil s to his students was a question that worried some of his col eagues as they watched Feynman plow apart the mathematical-methods syl abus. Nevertheless, during the few years that he taught the course, it drew some of the younger members of the physics and mathematics faculty along with the captive graduate students. The coolest among them had to feel the jolt of an examination problem that began, “In an atom bomb in the form of a cylinder radius a , height 2π, the density of neutrons n …” The students found themselves in the grip of a theorist whose obsession with mathematical methods concerned the uneasy first principles of quantum mechanics. Again and again he showed his affinity with the purest core issues of the propagation of sound and light.

He drove his students through calculations of the total intensity of radiation in al directions when emitted by a periodic source; through the reluctant visualization of vectors, matrices, and tensors; through the summations of

infinite series that sometimes converged and sometimes failed to converge, running inconveniently off toward infinity.

Gradual y he settled in at Cornel , though he stil made no progress on his theoretical research. The atomic bomb was on his mind, and he went on the local radio to speak about it in unadorned language. Announcer: Last week Dr.

Feynman told you what one atom bomb did to Hiroshima, and what one bomb would do to Ithaca … The interviewer asked about atomic-powered automobiles. Many listeners, he said, were awaiting the day when they could slip a spoonful of uranium into the tank and thumb their noses at the fil ing stations. Feynman said he doubted the practicality of that—“the rays emitted by the fission of the uranium in the engine would kil the driver.” Stil , he had spent time working out other applications of nuclear power.

At Los Alamos he had invented a type of fast reactor for generating electric power and had patented it (in the government’s behalf). He was also thinking about space travel. “Dear Sir,” he wrote to a physicist col eague as 1945

came to a close, “I believe that interplanetary travel is now (with the release of atomic energy) a definite possibility .”

He had a radical y quirky, almost flaky, proposal. Rocket propulsion would not be the answer, he said. It was fundamental y limited by the temperature and atomic weight of the propulsive gas, the temperature in turn being limited by the ability of metal to withstand heat. He predicted—

anticipating the ungainly disposable boosters and giant fuel tanks that became the curse of space travel thirty years in

the future—that the weight and bulk of fuel would exceed by too many times the weight and bulk of the vehicle.

Instead he proposed a form of jet propulsion, using air as the propel ant. Jet technology had just now reached practicality in airplanes. Feynman’s spacecraft would use the outer edges of the earth’s atmosphere as a sort of warm-up track and accelerate as it circled the earth. An atomic reactor would power the jet by heating the air that was sucked into the engine. Wings would be used first to provide lift and then, when the speed rose beyond five miles per second, “flying upside down to keep you from going off the earth, or rather out of the atmosphere.” When the craft reached a useful escape velocity, it would fly off at a tangent toward its destination like a rock from a slingshot.

Yes, air resistance, heating the ship, would be a problem. But Feynman thought this could be overcome by delicately adjusting the altitude as the craft sped up—“if there is enough air to cause appreciable heating by friction there surely is enough to feed the jet engines.” The engines would need impressive engineering to operate in such a wide range of air densities, he admitted. He did not address a problem of symmetry: how such a spacecraft would slow down on reaching an airless destination such as the moon. In any event he could not have anticipated the kil ing flaw in his idea: that people would lose faith in the innocence of nuclear reactors flying about overhead.

They All Seem Ashes

He visited Far Rockaway just before the fal semester began in 1946 and gave another talk on the atomic bomb at the local Temple Israel the day after Yom Kippur. The synagogue had a glamorous new rabbi, Judah Cahn, who delivered widely admired sermons on modern problems.

Feynman’s parents, despite their atheism, had started attending from time to time. Melvil e’s health seemed slightly better. His uncontrol able high blood pressure had become a constant source of worry to the family, and in the preceding spring he had traveled out to the Mayo Clinic, in Minnesota, where he was enrol ed in an early experiment on the effect of diet. He accepted a strict regimen of rice and fruit. It seemed to work. His blood pressure decreased.

He returned home and occasional y sneaked out, in violation of doctors’ orders, to play golf with friends. He was fifty-six years old. One day Feynman saw him at the table, staring at a salt shaker. Melvil e closed one eye, opened it, closed the other eye, and said he had a blind spot. A smal blood vessel must have burst in his brain, he said.

The knowledge that sudden death might come at any time hung over the family. Melvil e and his son almost never wrote each other—Lucil e handled the intrafamily correspondence—but when Richard first accepted the Cornel professorship he sent his father a letter expressing twenty-five years of love and gratitude, and Melvil e, moved, responded in kind. His chest was swel ed with pride, he wrote (while Lucil e complained that he was wasting paper by writing on only one side):

It is not so easy for a Dope of a father to write to a son who has already arrived to a state of learning and wisdom beyond his… . That was al right when you were smal and I had a great advantage over you—but today it would be more equitable if I could bask in the sunlight of your knowledge, and sit by your side and learn from you some of the more wondrous secrets of nature that now are beyond my ken but are known to you.

On October 7 he col apsed from a stroke. He died the next day. Richard signed his second death certificate in two years. Melvil e Feynman had written him: “The dreams I have often had in my youth for my own development, I see coming true in your career… . I envy the life of culture you wil have being constantly with so many other big men of equal culture.”