Making of the Atomic Bomb

by Richard Rhodes

  The prospect of coming to Los Alamos aroused great misgivings.1756 It was to be a military post; men were asked to sign up more or less for the duration; restrictions on travel and on the freedom of families to move about would be severe. . . . The notion of disappearing into the New Mexico desert for an indeterminate period and under quasi-military auspices disturbed a good many scientists, and the families of many more. But there was another side to it. Almost everyone realized that this was a great undertaking. Almost everyone knew that if it were completed successfully and rapidly enough, it might determine the outcome of the war. Almost everyone knew that it was an unparalleled opportunity to bring to bear the basic knowledge and art of science for the benefit of his country. Almost everyone knew that this job, if it were achieved, would be a part of history. This sense of excitement, of devotion and of patriotism in the end prevailed. Most of those with whom I talked came to Los Alamos.

  One of the most tough-minded, I. I. Rabi, did not. His reasons are revealing. He continued developing radar at the Radiation Laboratory at MIT. “Oppenheimer wanted me to be the associate director,” he told an interviewer many years later. “I thought it over and turned him down. I said, ‘I’m very serious about this war. We could lose it with insufficient radar.’ ”1757 The Columbia physicist thought radar more immediately important to the defense of his country than the distant prospect of an atomic bomb. Nor did he choose to work full time, he told Oppenheimer, to make “the culmination of three centuries of physics” a weapon of mass destruction.1758 Oppenheimer responded that he would take “a different stand” if he thought the atomic bomb would serve as such a culmination. “To me it is primarily the development in time of war of a military weapon of some consequence.”1759 Either Oppenheimer had not yet thought his way through to a more millenarian view of the new weapon’s implications or he chose to avoid discussing those implications with Rabi. He asked Rabi only to participate in an inaugural physics conference at Los Alamos in April 1943 and to help convince others, particularly Hans Bethe, to sign on. Eventually Rabi would come and go as a visiting consultant, one of the very few exceptions to Groves’ compartmentalization and isolation rules.

  Oppenheimer talked to the Bethes in Cambridge in snowy New England December; they questioned him at length about the life they would be asked to lead. Extracts from his letter of response sketch the invention of an instant community: “Laboratory . . . town . . . utilities, schools, hospitals . . . a sort of city manager . . . city engineer . . . teachers . . . M.P. camp . . . a laundry . . . two eating places . . . a recreation officer . . . libraries, pack trips, movies . . . bachelor apartments . . . a so-called Post Exchange . . . a vet . . . barbers and such like . . . a cantina where we can have beer and cokes and light lunches.” The Bethes’ best guarantee of satisfaction, Oppenheimer concluded, “is in the great effort and generosity that . . . Groves [has] brought to setting up this odd community and in [Groves’] evident desire to make a real success of it. In general [he is] not interested in saving money, but . . . in saving critical materials, in cutting down personnel, and in doing nothing which would attract Congressional attention to our hi-jinks.” He chose not to mention the security arrangements, in the development of which he was participating: the perimeter fence, the pass controls, the virtual elimination of telephones (“Oppenheimer’s idea was one telephone for himself,” says Dudley, “one for the post commander, and any volume business would go out over a teletype.”1760, 1761 ). By March Teller found Bethe taking “a very optimistic view, and there was no need whatever to persuade him to come.”1762

  Teller felt underemployed in Chicago and was eager to move to the new laboratory. John Manley asked him to write a prospectus to help with recruiting, which Teller sent to Oppenheimer in early January. During the Berkeley summer study the two men had begun what another participant judged a “mental love affair.”1763, 1764 Teller “liked and respected Oppie enormously. He kept wanting to talk about him with others who knew him, kept bringing up his name in conversation.” Bethe noticed then and later that despite their many outward differences Teller and Oppenheimer were “fundamentally . . . very similar.1765 Teller had an extremely quick understanding of things, so did Oppenheimer. . . . They were also somewhat alike in that their actual production, their scientific publications, did not measure up in any way to their capacity. I think Teller’s mental capacity is very high, and so was Oppenheimer’s but, on the other hand, their papers, while they included some very good ones, never reached really the top standards. Neither of them ever came up to the Nobel Prize level. I think you just cannot get to that level unless you are somewhat introverted.” (Luis Alvarez, the 1968 physics Nobel laureate, disagrees, at least where Oppenheimer is concerned.1766 He believes Oppenheimer would have won a Nobel Prize for his astrophysical work if he had lived long enough to see his predictions concerning exotic stellar objects—neutron stars, black holes—confirmed, as they have been, by discovery.) Both Oppenheimer and Teller wrote poetry; Oppenheimer pursued literature as Teller pursued music; and for a time in 1942 and 1943 the Hungarian apparently admired the older and socially more sophisticated New Yorker and hoped to count him for an ally.

  As Oppenheimer traveled the country recruiting he discovered to his surprise that few of his colleagues were attracted to the notion of joining the Army. It fell to Rabi and his Rad Lab colleague Robert F. Bacher, during the weeks before Rabi decided to stay in Cambridge, to lead the revolt. The necessity of “scientific autonomy” was one crucial reason they cited for resisting militarization, Oppenheimer wrote Conant at the beginning of February 1943, and they insisted as a corollary that although “the execution of the security and secrecy measures should be in the hands of the military . . . the decision as to what measures should be applied must be in the hands of the Laboratory.” On that point Oppenheimer concurred, “because I believe it is the only way to assure the cooperation and the unimpaired morale of the scientists.” The stakes were higher than simply losing Rabi and Bacher, Oppenheimer told Conant: “I believe that the solidarity of physicists is such that if these conditions are not met, we shall not only fail to have the men from M.I.T with us, but that many men who have already planned to join the new Laboratory will reconsider their commitments or come with such misgivings as to reduce their usefulness.” A rebellion, he concluded, would mean “a real delay in our work.”1767

  Groves had wanted the scientists commissioned as a security measure and because their work might be hazardous. He was hardly interested in the politics of the question, but delay was unthinkable. He compromised. Conant wrote a letter, co-signed by Groves, that Oppenheimer could use in recruiting; it allowed the new laboratory civilian administration and civilian staff until the time of hazardous large-scale trials. Then anyone who wanted to stay would have to accept a commission (a provision Groves chose later not to pursue). The Army would administer the community it was building around the laboratory. Laboratory security would be Oppenheimer’s responsibility, and he would report to Groves.

  Robert Oppenheimer thus acquired for Los Alamos what Leo Szilard had not been able to organize in Chicago: scientific freedom of speech. The price the new community paid, a social but more profoundly a political price, was a guarded barbed-wire fence around the town and a second guarded barbed-wire fence around the laboratory itself, emphasizing that the scientists and their families were walled off where knowledge of their work was concerned not only from the world but even from each other. “Several of the European-born were unhappy,” Laura Fermi notes, “because living inside a fenced area reminded them of concentration camps.”1768

  * * *

  The heavy-water installation at Vemork in southern Norway became a target of British sabotage operations in the winter of 1942–43. The British had been planning to send in two glider-loads of demolition experts, thirty-four trained volunteers; when Groves requested Allied action soon after his appointment to administer the Manhattan Project they moved ahead to comply. An advance party of f
our Norwegian commandos parachuted into the Rjukan area on October 18 to prepare the way, but bad planning and bad weather brought disaster to the gliders on the night of November 19 when they crossed the North Sea from Scotland; both crashed in Norway, one into a mountainside, and the fourteen men who survived the separate disasters were captured by German occupation forces and executed the same day.

  R. V. Jones, an Oxford protégé of Cherwell who was now director of intelligence for the British Air Staff, then had “one of the most painful decisions that I had to make” —whether to send another demolition party after the first. “I reasoned that we had already decided, before the tragedy of the first raid and therefore free from sentiment, that the heavy water plant must be destroyed; casualties must be expected in war, and so if we were right in asking for the first raid we were probably right in asking that it be repeated.”

  This time six men, Norwegians native to the region and trained as Special Forces, parachuted onto a frozen lake thirty miles northwest of Vemork on February 16, 1943, the night of a full moon.1769 “Here lay the Hardanger Vidda,” one of them, Knut Haukelid, writes of the high plateau that surrounded the lake, “the largest, loneliest and wildest mountain area in northern Europe.” The men wore white jumpsuits over British Army uniforms and parachuted with skis, supplies, a shortwave radio and eighteen sets of plastic explosives, one for each of the eighteen stainless-steel electrolysis cells of the High Concentration Plant—which happened to have been designed by a refugee physical chemist, Lief Tronstad, who was now responsible to the Norwegian High Command in London for intelligence and sabotage. Haukelid, a powerfully built mountaineer, says they weathered “one of the worst storms I have ever experienced in the mountains” to rendezvous some days later with the four Norwegians of the original advance party, who had been forced to hide out on the barren Hardanger Vidda and were malnourished and weak.1770, 1771, 1772 The new arrivals fattened up their compatriots while one of them skied on to Rjukan to gather the latest information about the plant. He returned to report minefields laid around the obvious approaches, guards on the suspension bridge that crossed the sheer gorge above the shelf on which the hydrochemical facility was built but only fifteen German soldiers on duty despite the forewarning of the failed glider attack. The factory itself was fitted with searchlights and guarded with machine guns.

  The commandos set out mid-evening on Saturday, February 27, leaving one man behind to guard the radios. They carried cyanide capsules and agreed that if anyone was wounded he would take his own life rather than allow himself to be captured and risk betraying his comrades. They had camped high on the mountain across the gorge from the plant, which was located to take advantage of the fall of water from the lake that fed it, Tinnsjö. “Halfway down we sighted our objective for the first time, below us on the other side. The great seven-storey factory building bulked large on the landscape. . . . [The wind] was blowing fairly hard, but nevertheless the hum of the machinery came up to us through the ravine. We understood how the Germans could allow themselves to keep so small a guard there. The colossus lay like a mediaeval castle, built in the most inaccessible place, protected by precipices and rivers.”1773

  They crashed down through soft snow all the way to the bottom of the gorge, crossed the frozen river, climbed up toward the plant on the other side. Above at the elevation of the shelf was a seldom-used railroad siding leading into the compound that they hoped the Germans had chosen not to mine. “It was a dark night and there was no moon,” Haukelid remembers. The searchlights were kept turned off and the high wind “drowned all the noise we made. Half an hour before midnight we came to a snow-covered building five hundred yards from Vemork, where we ate a little chocolate and waited for the change of sentries.”1774 They divided into two groups, a demolition party and a covering party. “We were well armed: five tommy-guns among nine men, and everyone had a pistol, a knife and hand grenades.”1775

  In an hour, time for the sentries to settle, they attacked. Haukelid in the covering party led the way. With bolt cutters they snipped “the thin little iron chain which barred the way to one of the most important military objectives in Europe.”1776 The covering party dispersed to its prearranged positions—Haukelid and one other man took up posts twenty yards from the Wehrmacht barracks, a flimsy wooden building they saw they could easily shoot through—and the demolition party moved ahead. The doors on the ground floor of the plant were locked, but Tronstad in London had identified for the commandos a cable intake that they could crawl along that led directly to the heavy-water facility. Two men looked for some other entrance while two disappeared into the cable intake.

  After what seemed to Haukelid an interminable delay he heard an explosion, “but an astonishingly small, insignificant one. Was this what we had come over a thousand miles to do?” The guards were slow to check; only one German soldier appeared and seemed not to realize what had happened; he tried the doors to the plant, found them locked, looked to see if snow falling from the mountain above had detonated a land mine and returned to his quarters.1777 The Norwegians moved out fast. They had descended to the river before the sirens began to sound.

  The operation was successful. No one was injured on either side. All eighteen cells had been blown open, spilling nearly half a ton of heavy water into the drains. Not only would the plant require weeks to repair; because it was a cascade, pumping water of increasing deuterium concentration from one cell to the next, it would need almost a year of operation after repair simply to reach equilibrium again on its own and begin producing. General Nikolaus von Falkenhorst, the commander in chief of the occupying German Army in Norway, called the Vemork attack “the best coup I have ever seen.”1778 Whatever German physicists might be doing with heavy water, they would do it more slowly now.

  * * *

  In Japan both the Army Air Force and the Imperial Navy had moved separately since 1941 to promote atomic bomb research.1779 The Riken, Yoshio Nishina’s prestigious Tokyo laboratory, primarily served the Army, exploring the theoretical possibilities of U235 separation by way of the gaseous barrier diffusion, gaseous thermal diffusion, electromagnetic and centrifuge processes. In the spring of 1942 the Navy committed itself to developing nuclear power for propulsion:

  The study of nuclear physics is a national project.1780 Research in this field is continuing on a broad scale in the United States, which has recently obtained the services of a number of Jewish scientists, and considerable progress has been made. The objective is the creation of tremendous amounts of energy through nuclear fission. Should this research prove successful, it would provide a stupendous and dependable source of power which could be used to activate ships and other large pieces of machinery. Although it is not expected that nuclear energy will be realized in the near future, the possibility of it must not be ignored. The Imperial Navy, accordingly, hereby affirms its determination to foster and assist studies in this field.

  Soon after that nonviolent affirmation, however, the Naval Technological Research Institute appointed a secret committee of leading Japanese scientists—corresponding to the U.S. National Academy of Sciences committee—to meet monthly to follow research progress until it could report decisively for or against a Japanese atomic bomb. The committee included Nishina, who was forthwith elected chairman. An elderly appointee was Hantarō Nagaoka, whose Saturnian atomic model had nearly anticipated Ernest Rutherford’s planetary model in the early years of the century.

  The Navy committee met first on July 8 with the Navy’s chief technical officers at an officers’ club at Shiba Park in Tokyo. It noted that the United States was probably working on a bomb and agreed that whether and how soon Japan could produce such a weapon was as yet uncertain. To the task of answering those questions the Navy appropriated 2,000 yen, about $4,700, somewhat less than the Uranium Committee had summoned from the U.S. Treasury at Edward Teller’s request at the beginning of the American program in 1939.

  Nishina hardly participated in the Navy committee me
etings. The fact that he was already working for the Army probably constrained him; the two services, both of which were responsible directly to the Emperor without detour through the civilian government, operated far more independently than their American counterparts and were increasingly bitter rivals. Nishina was coming to conclusions of his own, however, and at the end of 1942, when the Navy committee began to report discouragement, he met privately with a young cosmic-ray physicist in his laboratory, Tadashi Takeuchi, told his young colleague he meant to carry forward isotope separation studies and asked him to help. Takeuchi agreed.

  Between December 1942 and March 1943 the Navy committee organized a ten-session physics colloquium to work through to a decision. By then it was understood that a bomb would necessitate locating, mining and processing hundreds of tons of uranium ore and that U235 separation would require a tenth of the annual Japanese electrical capacity and half the nation’s copper output. The colloquium concluded that while an atomic bomb was certainly possible, Japan might need ten years to build one. The scientists believed that neither Germany nor the United States had sufficient spare industrial capacity to produce atomic bombs in time to be of use in the war.

  After the final March 6 meeting the Navy representative at the colloquium reported discouragement: “The best minds of Japan, studying the subject from the point of view of their respective fields of endeavor as well as from that of national defense, came to a conclusion that can only be regarded as correct. The more they considered and discussed the problem, the more pessimistic became the atmosphere of the meeting.”1781 As a result the Navy dissolved the committee and asked its members to devote themselves to more immediately valuable research, particularly radar.