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

What materials would best serve as tamper, a surrounding liner that would reflect neutrons back into the bomb? The metal urgists had to begin the work of

fabricating tamper long before a true test was possible.

How pure would the uranium have to be? On this calculation rested a decision to build or not build an enormous third stage in the isotope-separation complex at Oak Ridge.

How much heat, how much light, how much shock would a nuclear explosion create in the atmosphere?

The Battleship and the Mosquito Boat

They occupied a two-story green-painted box cal ed T

building (T for theoretical), which Oppenheimer made his headquarters and the laboratory’s spiritual center. He placed Hans Bethe, Cornel ’s famous nuclear physicist, in charge. The corridors were narrow, the wal s thin. As the scientists worked, they would hear from time to time Bethe’s booming laughter. When they heard that laugh they suspected that Feynman was nearby.

Bethe and Feynman—strange pair, some of their col eagues thought, a pedantic-seeming German professor and a budding quicksilver genius. Someone coined the nicknames “Battleship” and “Mosquito Boat.” Their col aborative method was for Bethe to plow solidly ahead, a determined giant, while Feynman buzzed back and forth across his bow, gesticulating, yel ing in his scabrous New York accent, “You’re crazy” and “That’s nuts.” Bethe would respond calmly in his slow professorial way, working his way through the problem analytical y and explaining that he

was not crazy, Feynman was crazy. Feynman would consider and pace back and forth, and final y through the partitions the other scientists would hear him shout back,

“No, no, you’re wrong .” He was reckless where Bethe was careful, and he was just what Bethe was looking for, someone who would perform the severest and most imaginative criticism, who would find flaws before an idea went too far. Chal enges and fresh insights came easily from Feynman. He did not wait, as Bethe did, to double-check every intuitive leap. His first idea did not always work. His cannier col eagues developed a rule of thumb: If Feynman says it three times, it’s right.

Bethe was a natural choice as leader of the theoretical division. His sweeping three-article review of the state of nuclear physics in the thirties had established him as the authoritative theorist in that field. As Oppenheimer wel knew, Bethe had not just organized the existing knowledge of the subject but had calculated or recalculated every line of theory himself. He had worked on probability theory, on the theory of shock waves, on the penetration of armor by artil ery shel s (this last paper, born of his eagerness in 1940 to make some contribution to the looming war, was immediately classified by the army so that Bethe himself, not yet an American citizen, could not see it again). His explanation in 1938 of the thermonuclear fires that light the sun would win him the Nobel Prize. Since arriving at Cornel in 1935 he had made it one of the new world centers in physics, as Oppenheimer and Ernest O. Lawrence had done for Berkeley.

Oppenheimer wanted him badly and strained to persuade him that the atomic bomb was practical enough to draw him from the MIT Radiation Laboratory, where he had begun to make a contribution in 1942. (When Bethe agreed, the news was sent to Oppenheimer by a prearranged code: a Western Union kiddiegram.) Bethe’s friend Edward Tel er had pressed hard for his participation.

No one but Tel er was now surprised when Oppenheimer appointed Bethe, the sturdy pragmatist, to head the theoretical division, to nurse the egos and the prodigies, to run the most eccentric, temperamental, insecure, volatile assortment of thinkers and calculators ever squeezed together in one place.

Bethe had learned his physics al across Europe: first at Munich, where he studied with Arnold Sommerfeld, a prodigious producer of future Nobel Prize winners, and then at Cambridge and Rome. At Cambridge, Dirac’s lectures on the new quantum mechanics held center stage, but Bethe quit attending after discovering that Dirac, having perfected his formulation of the subject, was simply reading his book aloud. At Rome, where he was the first foreign student of physics in the university’s history, the attraction was Fermi. For a short time they worked together closely, and Bethe acquired from him a style that he cal ed

“lightness of approach.” His first great teacher, Sommerfeld, had always begun work on a problem by writing down a formalism selected from a heavy arsenal of mathematical equipment. He would work out the equations and only then translate the results into an understanding of

the physics. By contrast, Fermi would begin by gently turning a problem over in his mind, by thinking about the forces at work, and only later sketching out the necessary equations. “Lightness” was a difficult attitude to sustain in a time of abstract, unvisualizable quantum mechanics. Bethe combined the physicality of Fermi’s attitude with an almost compulsive interest in computing the actual numbers that an equation entailed. That was far from typical. Most physicists could happily string equations down a page, working out the algebra without keeping in mind a sense of real quantities, or ranges of quantities, that a symbol might represent. For Bethe a theory only mattered when he could get actual numbers out.

From Fermi’s Rome, Bethe returned to a Germany whose scientific establishment was nearing the precipice.

In his classroom at the ancient university of Tübingen, where he took an assistant professorship, he saw students wearing swastikas on arm bands. It was the autumn of 1932. That winter Hitler took power. In February the Reichstag burned. By spring the first of the Nazis’ anti-Jewish ordinances entailed the immediate dismissal of one-fourth of the country’s university physicists—non-Aryan civil servants. Bethe, his father a Prussian Protestant, did not consider himself a Jew, but because his mother was Jewish his status in Nazi Germany was clear. He was immediately shed from the faculty he had just entered.

Across Europe the greatest intel ectual migration in history was already beginning, and Bethe had little choice but to join it. Scientists in general had the advantage of working in

a polyglot community, where international study and temporary overseas lectureships eased their emotional transition—from citizen to refugee. He reached the New World in 1935.

Feynman had known Bethe’s name since he was an undergraduate—the Bethe Bible, the three famous review articles on nuclear physics, had provided the entire content of MIT’s course. He had seen Bethe once from a distance at a scientific meeting. An ugly man, he had thought at first glance, awkward, with slightly squashed features on a strong frame, light brown hair bristling skyward above a broad brow. Feynman’s first impression dissolved when they met up close in Santa Fe before heading up to Los Alamos for the first time. Bethe, thirty-seven years old, had the body of a mountain climber, and he spent as much time as possible hiking in the canyons or up to the peaks behind the laboratory. He radiated solidity and warmth. Soon after their arrival on the mesa, a statistical fluctuation in the comings and goings of the theorists left Bethe stripped of the people he needed to consult. Victor Weisskopf, his deputy, was away. Tel er was away—but Tel er, anyway, had immediately grown more aloof than useful; not only had Oppenheimer passed him over in favor of Bethe, but Bethe had passed him over in favor of Weisskopf. So Bethe drifted into Feynman’s office one day, and soon people down the corridor could hear his booming laugh.

Bethe left the initial lectures trying to work out a way of calculating the efficiency of a nuclear explosion. Serber had presented a formula for the simplest case, when the mass