by American Prometheus: The Triumph;Tragedy of J. Robert Oppenheimer
Finally, Bohr concluded that such a sweeping new regime of international control could be inaugurated after the war only by promptly inviting the Soviet Union’s participation in postwar atomic energy planning— before the bomb was a reality and before the war was over. A postwar nuclear arms race could be prevented, Bohr believed, if Stalin was informed of the existence of the Manhattan Project and assured that it posed no threat to the Soviet Union. An early agreement among the wartime allies for the postwar international control of atomic energy was the only alternative to a nuclear-armed world. Oppenheimer agreed—indeed, he had shocked his security officers the previous August when he told Colonel Pash that he would “feel friendly” to the idea of the president informing the Russians about the bomb project.
It was easy to see the effect Bohr had on Oppenheimer. “[He] knew Bohr from way back and they were pretty close personally,” said Weisskopf. “Bohr was the one who really discussed these political and ethical problems with Oppenheimer, and probably that was the time [early 1944] when he began to think seriously about it.” One afternoon that winter, Oppenheimer and David Hawkins were walking Bohr back to his guest quarters in Fuller Lodge when Bohr playfully insisted on testing the thickness of the ice on Ashley Pond. The usually daring Oppenheimer afterwards turned to Hawkins and exclaimed, “My God, suppose he should slip? Suppose he should fall through? What would we all do then?”
The very next day, Oppenheimer beckoned Hawkins into his office, pulled a folder from his secure file cabinet, and let him read a letter Bohr had written to Franklin Roosevelt. Oppie obviously set great store by the precious document. According to Hawkins, “the implication was that Roosevelt had fully understood. And this was a great source of joy and optimism. . . . It’s interesting. We all lived under this illusion, you see, for the rest of the time at Los Alamos, that Roosevelt had understood.”
BOHR HAD long since converted his particular “Copenhagen” interpretation of quantum physics into a philosophical world view that he named “Complementarity.” Bohr was forever trying to take his insights into the physical nature of the world and apply them to human relations. As the historian of science Jeremy Bernstein later wrote: “Bohr was not satisfied to limit the idea of complementarity to physics. He saw it everywhere: instinct and reason, free will, love and justice, and on and on.” He quite understandably saw it in the work at Los Alamos too. Everything about the project was fraught with contradictions. They were building a weapon of mass destruction that would defeat fascism and end all wars—but also make it possible to end all civilization. Oppenheimer quite naturally found it comforting to be told by Bohr that the contradictions in life were nevertheless all of a piece—and therefore complementary.
Oppenheimer so admired Bohr that in years to come he often took it upon himself to translate him to the rest of humanity. Not many understood what Bohr meant by an “open world.” And those who did were sometimes positively alarmed by the audacity of what Bohr was proposing. In the early spring of 1944, Bohr received a letter, long delayed in the mails, from one of his former students, the Russian physicist Peter Kapitza. Writing from Moscow, Kapitza warmly invited Bohr to come settle there, “where everything will be done to give you and your family a shelter and where we now have all the necessary conditions for carrying on scientific work.” Kapitza then passed on the greetings of a number of Russian physicists whom Bohr knew—broadly suggesting that they would all be delighted to have him join them in their “scientific work.” Bohr thought this a splendid opportunity, and he actually hoped that Roosevelt and Churchill would authorize him to accept Kapitza’s invitation. As Oppenheimer later explained it to his colleagues, Bohr wished “to propose to the rulers of Russia, who were then our Allies, via these scientists, that the United States and the United Kingdom ‘trade’ their atomic knowledge for an open world . . . that we propose to the Russians that atomic knowledge would be shared with them if they would agree to open Russia and make it an open country and part of an open world.”
To Bohr’s thinking, secrecy was dangerous. Knowing Kapitza and other Russian physicists, Bohr thought them perfectly capable of grasping the military implications of fission. In fact, he surmised from Kapitza’s letter that the Soviets already did know something about the British-American atomic program—and he thought it would only sow dangerous suspicions if the Russians concluded that the new weapon was being developed without them. Other physicists at Los Alamos agreed. Robert Wilson later recalled “bugging” Oppenheimer about why British scientists, but no Russian scientists, were working at Los Alamos. “It seemed to me that down the line,” Wilson said, “that was going to make for some very hard feelings.” By the war’s end, it is clear that Oppenheimer agreed, but during the war, he was circumspect, knowing that he was under constant surveillance, and so he always refused to be drawn into such conversations. Either he wouldn’t answer at all or he’d mutter that it wasn’t the business of the scientists to determine such things. “I don’t know,” Wilson later said, “I felt that perhaps he thought that I was testing him.”
Not surprisingly, Bohr’s attitude was not shared by the generals and politicians who employed the scientists. General Groves, for instance, never really thought of the Russians as allies. In 1954, he told the Atomic Energy Commission’s hearing board that “there was never from about two weeks from the time I took charge of this project any illusion on my part but that Russia was our enemy and that the project was conducted on that basis. I didn’t go along with the attitude of the country as a whole that Russia was a gallant ally.” Winston Churchill had a similar view of the Soviets, and he was outraged to learn of the Kapitza-Bohr correspondence from British intelligence. “How did he [Bohr] come into this business?” Churchill exclaimed to his science adviser, Lord Cherwell. “It seems to me Bohr ought to be confined or at any rate made to see that he is very near the edge of mortal crimes.”
Despite personal meetings with both Roosevelt and Churchill in the spring and summer of 1944, Bohr failed to persuade either leader that the Anglo-American monopoly in atomic matters was shortsighted. Groves later told Oppenheimer that he thought Bohr “was at times a thorn in the sides of everyone dealing with him, possibly because of his great mental capacity.” Ironically, as his influence with such political leaders waned, Bohr’s stature among the physicists at Los Alamos rose to new heights. Once again, Bohr was God and Oppie was his prophet.
BOHR HAD come to Los Alamos in December 1943 alarmed by what he had learned from his encounter with Heisenberg about the potential for a German bomb. He left Los Alamos that spring persuaded by intelligence reports that the Germans probably did not have a viable bomb program: “. . . from leakage regarding the activities of German scientists,” he noted, “it is practically certain that no substantial progress has been achieved by the Axis Powers.” If Bohr was convinced, then Oppenheimer too must have realized that the German physicists were in all likelihood far behind in the race to build a bomb. According to David Hawkins, Oppenheimer was told by General Groves at the end of 1943 that a German source had recently claimed that the Germans had abandoned their early bomb program. Groves suggested that it was hard to evaluate such a report; the German source might be passing on disinformation. Oppenheimer just shrugged. Hawkins recalled thinking to himself that it was too late—the men at Los Alamos “were committed to building a bomb regardless of German progress.”
CHAPTER TWENTY-ONE
“The Impact of the Gadget on Civilization”
My feeling about Oppenheimer was, at that time, that this was a man who is angelic, true and honest and he could do no wrong. . . . I believed in him.
ROBERT WILSON
EVERYONE SENSED OPPIE’S PRESENCE. He drove himself around The Hill in an Army jeep or in his own large black Buick, dropping in unannounced on one of the laboratory’s scattered offices. Usually he’d sit in the back of the room, chain-smoking and listening quietly to the discussion. His mere presence seemed to galvanize people to greater efforts. �
��Vicki” Weisskopf marveled at how often Oppie seemed to be physically present at each new breakthrough in the project. “He was present in the laboratory or in the seminar room when a new effect was measured, when a new idea was conceived. It was not that he contributed so many ideas or suggestions; he did so sometimes, but his main influence came from his continuous and intense presence, which produced a sense of direct participation in all of us.” Hans Bethe recalled the day Oppie dropped in to a session on metallurgy and listened to an inconclusive debate over what type of refractory container should be used for melting plutonium. After listening to the argument, Oppie summed up the discussion. He didn’t directly propose a solution, but by the time he left the room the right answer was clear to all.
By contrast, General Groves’ visits were always interruptions—and sometimes comically disruptive. One day, Oppie was showing Groves around a lab when the general put his considerable weight on one of three rubber tubes funneling hot water into a casing. As McAllister Hull recalled for the historian Charles Thorpe, “It [the rubber tube] pops off the wall and a stream of water just below the boiling point shoots across the room. And if you’ve ever seen a picture of Groves, you know what it hit.” Oppenheimer looked over his soaking-wet general and quipped, “Well, just goes to show the incompressibility of water.”
Oppie’s interventions sometimes proved to be absolutely essential to the success of the project. He understood that the single major impediment to building a usable weapon quickly was the meager supply of fissionable material. And so he was constantly looking for ways to accelerate the production of these materials. Early in 1943, Groves and his S-1 Executive Committee had settled on gaseous diffusion and electromagnetic technologies to separate out enriched fissionable uranium for the Los Alamos bomb lab. At the time, another possible technology, based on liquid thermal diffusion, had been rejected as unfeasible. But in the spring of 1944, Oppenheimer read some year-old reports about liquid thermal diffusion and decided that this had been a mistake. He thought this technology represented a relatively cheap path to providing partially enriched uranium for the electromagnetic process. So in April 1944, he wrote Groves that a liquid thermal diffusion plant might serve as a stopgap measure; its production of even slightly enriched uranium could then be fed to the electromagnetic diffusion plant and thereby accelerate production of fissionable material. It was his hope, he wrote, “that the production of the Y-12 [electromagnetic] plant could be increased by some 30 to 40 percent, and its enhancement somewhat improved, many months earlier than the scheduled date for K-25 [gaseous diffusion] production.”
After sitting on Oppie’s recommendation for a month, Groves agreed to explore it. A plant was rushed into production, and by the spring of 1945 it was producing just enough extra partially enriched uranium to guarantee a sufficient amount of fissionable material for one bomb by the end of July 1945.
Oppenheimer had always possessed a high degree of confidence in the uranium gun-design program—whereby a “slug” of fissionable material would be fired into a target of additional fissionable matter, creating “criticality” and a nuclear explosion. But in the spring of 1944, he suddenly faced a crisis that threatened to derail the entire effort to design a plutonium bomb. While Oppenheimer had authorized Seth Neddermeyer to conduct explosive experiments aimed at creating an implosion design bomb—a loosely packed sphere of fissionable material that could be instantly compressed to reach criticality—he had always hoped that a straightforward gun assembly would prove viable for the plutonium bomb. In July 1944, however, it became clear from tests performed on the first small supplies of plutonium that an efficient plutonium bomb could not be triggered within the “gun-barrel” design. Indeed, any such attempt would undoubtedly lead to a catastrophic pre-detonation inside the plutonium “gun.”
One solution might have been to separate further the plutonium materials in an attempt to make a more stable element. “One could have separated out those bad plutonium isotopes from the good ones,” John Manley explained, “but that would have meant duplicating everything that had been done for uranium isotope separation—all those big plants—and there was just no time to do that. The choice was to junk the whole discovery of the chain reaction that produced plutonium, and all of the investment in time and effort of the Hanford [Washington] plant, unless somebody could come up with a way of assembling the plutonium material into a weapon that would explode.”
On July 17, 1944, Oppenheimer convened a meeting in Chicago with Groves, Conant, Fermi and others, to resolve the crisis. Conant urged that they aim merely to build a low-efficiency implosion bomb based on a mixture of uranium and plutonium. Such a weapon would have had an explosive equivalent of only several hundred tons of TNT. Only after successfully testing such a low-efficiency bomb, Conant said, would the lab have the confidence to proceed with a larger weapon.
Oppenheimer rejected this notion on the grounds that it would lead to unacceptable delays. Despite having been skeptical about the implosion idea when it was first broached by Serber, Oppenheimer now marshaled all his persuasive powers to argue that they gamble everything on an implosion-design plutonium bomb. It was an audacious and brilliant gamble. Since the spring of 1943, when Seth Neddermeyer had volunteered to experiment with the concept, little progress had been made. But in the autumn of 1943, Oppenheimer brought the Princeton mathematician John von Neumann to Los Alamos, and von Neumann calculated that implosion was possible, at least theoretically. Oppenheimer was willing to bet on it.
The next day, July 18, Oppenheimer summarized his conclusions for Groves: “We have investigated briefly the possibility of an electromagnetic separation. . . . It is our opinion that this method is in principle a possible one but that the necessary developments involved are in no way compatible with present ideas of schedule. . . . In the light of the above facts, it appears reasonable to discontinue the intensive effort to achieve higher purity for plutonium and to concentrate attention on methods of assembly which do not require a low neutron background for their success. At the present time the method to which an overriding priority must be assigned is the method of implosion.”
Oppenheimer’s assistant, David Hawkins, later explained, “The implosion was the only real hope [for a plutonium bomb], and from current evidence not a very good one.” Neddermeyer and his men in the Ordnance Division were making very little progress on the implosion design. Neddermeyer, shy and retiring, liked to work alone, and methodically. He later admitted that Oppenheimer “became terribly impatient with me in the spring of 1944. . . . I think he felt very badly because I seemed not to push things as for war research but acted as though it were just a normal research situation.” Neddermeyer was also one of the few men on the mesa who seemed immune to Oppie’s charms. In his frustration, Oppie uncharacteristically began to lose his temper. “Oppenheimer lit into me,” Neddermeyer recalled. “A lot of people looked up to him as a source of wisdom and inspiration. I respected him as a scientist, but I just didn’t look up to him that way. . . . He could cut you cold and humiliate you right down to the ground. On the other hand, I could irritate him.” Stoked by this personality conflict, the crisis over the implosion design came to a head late that summer when Oppenheimer announced a major reorganization of the lab.
Early in 1944, Oppenheimer had persuaded an explosives expert from Harvard, George “Kisty” Kistiakowsky, to move to Los Alamos. Kistiakowsky was opinionated and strong-willed. Inevitably, he had numerous run-ins with his ostensible superior, Captain “Deke” Parsons. Neither did Kistiakowsky get along with Neddermeyer, who seemed to him far too lackadaisical in his approach. Early in June 1944, Kistiakowsky wrote Oppenheimer a memo threatening to resign. In response, Oppenheimer swiftly called Neddermeyer in and told him that Kistiakowsky was replacing him. Angry and hurt, Neddermeyer walked out. Although he would feel an “enduring bitterness,” he nevertheless was persuaded to remain in Los Alamos as a senior technical adviser. Acting decisively, Oppenheimer had announced this chang
e without first consulting Captain Parsons. “Parsons was furious,” recalled Kistiakowsky. “He felt that I had bypassed him and that was outrageous. I can understand perfectly how he felt, but I was a civilian, so was Oppie, and I didn’t have to go through him.”
Parsons chafed at what he considered a loss of control over his Ordnance Division, and in September he sent Oppie a memorandum proposing to give himself broad decision-making powers over all aspects of the implosion bomb project. Oppenheimer gently but firmly refused: “The kind of authority which you appear to request from me is something I cannot delegate to you because I do not possess it. I do not, in fact, whatever protocol may suggest, have the authority to make decisions which are not understood and approved by the qualified scientists of the laboratory who must execute them.” As a military man, Navy Captain Parsons wanted the authority in order to short-circuit the debates among his scientists. “You have pointed out,” Oppenheimer wrote him, “that you are afraid your position in the laboratory might make it necessary for you to engage in prolonged argument and discussion in order to obtain agreement upon which the progress of the work would depend. Nothing that I can put in writing can eliminate this necessity.” The scientists had to be free to argue—and Oppenheimer would arbitrate disputes only for the purpose of reaching some kind of collegial consensus. “I am not arguing that the laboratory should be so constituted,” he told Parsons. “It is in fact so constituted.”
