The Pope of Physics

by Gino Segrè

  37

  THE SUPER

  The debates about further exploration and use of nuclear energy were hotly pursued not only in the streets and homes of Americans but also in the corridors of Washington. The atomic bomb was not an apparition; it was here to stay. Security issues and military applications overshadowed moral and ethical considerations. How many bombs could or should be built? Could they be made bigger? How soon would other countries possess the technology to make bombs?

  During the immediate post–World War II years, United States government circles pondered how nuclear weapon development and nuclear power management should be regulated. These concerns were intensely argued as the Atomic Energy Act made its way through Congress in 1946. Several physicists, Szilard and Oppenheimer in particular, had tried to influence its formulation. A major bone of contention revolved around technology transfer—that is, sharing research with other scientists and countries. The act in its final form specified that all information regarding nuclear weapons was classified unless specifically indicated otherwise. Given the increasing hostility between the United States and the Soviet Union, attempts to either ban nuclear weapons or have an international control system were tabled.

  Another contentious question was the proposed shift of all atomic energy production facilities from military to civilian control. When President Truman signed the act into law in August, the Manhattan Project basically morphed into the Atomic Energy Commission (AEC). Los Alamos was no longer under the aegis of the army. Instead, it was operated by the University of California in a contractual agreement with the AEC. A new director, Norris Bradbury, a Stanford University professor who had been at the laboratory since 1944, became Oppenheimer’s successor.

  A provision of the AEC, a civilian board of five members, was that it was to consult regularly with a General Advisory Committee of nine scientists. When it was effectuated on January 1, 1947, Fermi was named to serve on the GAC. The president had asked him and he, as a good citizen, felt he could not refuse. Fermi anticipated that his appointment would be relatively apolitical, focusing on technical questions. Instead, it would force him to take a public stand on one of the most perilous questions the world could imagine.

  Fermi assiduously tried to avoid the political arena. Writing in January 1946 to Edoardo Amaldi, Fermi mocked those physicists who “are much more occupied with politics rather than science and are spending their time in pleasant conversations with senators and congressmen.” Divisions among scientists characteristically ran deep. Fermi skirted around the personality clashes between Teller and Oppenheimer as well as the national controversies between advocates and opponents of weapon proliferation. The most astonishing fact is that physicists on both sides of a given issue seemed to universally like Fermi, forgiving and excusing his neutrality. In the words of Norris Bradbury, “No man could have been more respected for his achievements, nor more loved for himself.”

  The GAC’s first meeting took place in Washington on January 3. The group—almost all of whom had been involved in the Manhattan Project—chose Oppenheimer to chair the committee. They also decided not to keep minutes of their discussions; at the end of each meeting they would submit a set of recommendations to the AEC.

  As their first task, the AEC decided to assess the nuclear stockpile in Los Alamos. On a site visit, commission members were shocked by what they found there. No nuclear weapons were ready for use, an especially frightening realization since they had assumed, as had the president, that America’s nuclear stockpile was the deterrent to the Soviet Union’s far greater land army in Europe. The laboratory reorganized and developed a formidable nuclear arsenal over the next few months.

  A topic that hovered over the AEC was whether to initiate a crash program for building a hydrogen bomb, or H-bomb, alternatively called the Super. Based on fusion rather than on fission, the Super was potentially thousands of times more powerful than the A-bomb. The prospect had obsessed Edward Teller since Fermi had casually introduced it during an after-lunch stroll in September 1941. Fermi had been musing whether fission could re-create on earth the conditions present in the sun’s core, reaching temperatures above 15 million degrees Centigrade, sufficient for fusing hydrogen nuclei into helium ones. The idea was fleeting for Fermi, but Teller fixated on it.

  The concept had been discussed the day after the Nagasaki bombing by the same scientific panel that had given advice on whether or not to drop the A-bomb. The four panel members feared that once the military heard of the possibility for a more powerful bomb, they would want to pursue it. The panel were not in favor of doing so but felt they needed to pose the question. In a set of recommendations, they wrote that prospects for developing the Super were “quite favorable.” But panel members continued by asserting, “We believe that the safety of this nation—as opposed to its ability to inflict damage on an enemy power—cannot be wholly or even primarily in its scientific or technical prowess. It can be based only on making future wars impossible.” They were unanimous in their belief that possessing the weapon would not protect the country from future war.

  The matter was largely left open afterward; it was still unknown whether such a formidable weapon could actually be built. With the formation of the AEC, the idea of the Super surfaced again. The commission’s first chairman, David Lilienthal, a progressive attorney known for leading the Tennessee Valley Authority, regarded such a prospect as obscene, a form of technological fanaticism. Given that such a bomb would be far more destructive than one employing a fission mechanism, he felt it could only be a weapon of mass destruction and therefore could not be justified on moral grounds. Lilienthal wanted nothing to do with it.

  Pressures mounted on September 23, 1949, with Truman’s announcement of the atmospheric detection of a Russian nuclear bomb explosion. Labeled Joe-1 as a nod to the Soviet Union’s leader, Joseph Stalin, it suggested that America could no longer reign supreme over advanced weaponry and that stockpiling fission weapons could not be counted on as a sufficient deterrent to war. However, to the chagrin of the congressional committee charged with overseeing the AEC, Lilienthal did not put the Super on the AEC’s October 5 agenda.

  Incensed by what he perceived as Lilienthal’s obstructionism, Lewis Strauss, one of the five AEC members, took matters into his own hands. Circumventing the regular channels of communication, he asked the secretary of the National Security Council to immediately take the matter up directly with the president. Truman was again surprised. He had not been told about the A-bomb’s existence until after Roosevelt’s death. Now, four years later, he once again had been left in the dark. On October 6, 1949, he was informed for the first time about another potential weapon—the Super.

  These events triggered a flurry of meetings and memos. Should Los Alamos gear up for another crisis? Who would or would not join the effort? Teller, based in Chicago but with summers dedicated to H-bomb research in Los Alamos, had already decided to spend the 1949–50 academic year at the laboratory. He now led the charge to develop an “all hands on deck” approach, meeting with key physicists such as Hans Bethe, James Conant, Ernest Lawrence, John Wheeler, and Luis Alvarez, all previously involved with the A-bomb. He argued for a crash program for the H-bomb, a rebirth of the intensity afforded the A-bomb. A new Manhattan Project was essential for survival, according to Teller.

  Due to coincidental luck, at least in his mind, Fermi had escaped the turmoil. He had left for Italy in late September on a long-planned visit, his first since the war. However, he was expected back in the States in time to attend the GAC’s critical next meeting, scheduled for October 29 and 30. After his eighteen-hour flight, none other than Teller greeted an exhausted Fermi at the Chicago airport, urging him to come immediately to Los Alamos and join the H-bomb push. Fermi, regarding his colleague as close to maniacal on the subject, was noncommittal. For the moment at least, his sights were focused on getting to the GAC meeting in Washington.

  It became clear at the late-October meeting that none of th
e GAC’s members was in favor of a crash program for the Super, although their degree of opposition varied. Conant was flatly opposed on moral grounds, while Fermi and Rabi were intrigued with the scientific feasibility of developing such weaponry. But the argument that it was necessary to have an H-bomb for defense and retaliation purposes against the Soviets held no sway with any of them. An arsenal of conventional nuclear bomb bombs, the GAC argued, would be more than enough.

  While essentially agreeing among themselves, GAC members could not come to consensus on the language of their recommendations, so the report has two annexes. Each annex includes references to genocide, a powerful word introduced in 1944 to describe crimes against humanity. Fermi and Rabi unexpectedly penned the stronger of the two annexes, voicing firm opposition: “The fact that no limit exists to the destructiveness of this weapon makes its very existence and the knowledge of its construction a danger to humanity as a whole. It is necessarily an evil thing in any light.” Their annex concluded by appealing to the president “to tell the American public, and the world, that we think it is wrong on fundamental ethical principles to initiate a program of the development of such a weapon.”

  Shortly after Fermi returned to Chicago from the meetings, Leona Woods Marshall stormed into his office. She had heard of Fermi’s position on the Super and could not fathom how he, as someone who always sought knowledge, “could have voted against finding out whether the hydrogen bomb worked.” Confronted by one of his closest colleagues, a woman haranguing him about not proceeding with devastating weaponry, Fermi “flared up,” according to Woods Marshall, leaving both of them “shaking and speechless.” She had witnessed Fermi’s occasional outbursts, recalling his childhood nickname of Little Match, but had not yet borne the brunt of his temper. For months afterward, the two of them stepped gingerly around each other, the wounds of their battle over the Super slowly healing.

  When the AEC took a vote on the issue, it was three to two against developing the Super. But Congress and the Joint Chiefs of Staff countered the recommendations of the GAC scientists and of the AEC vote. The controversy was stoked further on January 24, 1950, by the British Secret Service’s arrest of the German refugee Klaus Fuchs on suspicion of being a Soviet spy. Fuchs had not left Los Alamos until August 1946 and had been present during all the initial Los Alamos discussions about building an H-bomb. Could he, a brilliant physicist, have shared this possibility with the Soviets? Might they have forged ahead in the direction of the Super?

  A few days later, on January 31, 1950, President Truman made an announcement applauded by most politicians but criticized by the majority of scientists. He directed the AEC to work on the Super. Teller felt triumphant. In addition, Truman placed a gag order on the GAC scientists, forbidding them to speak publicly about the details of the decision. A veil of secrecy once again descended.

  Fermi found this exasperating. He had opposed secrecy on neutron research in 1940, bowing to pressure as he saw war becoming imminent. Then, there was at least a good reason for silence. But the postwar constraints of secrecy, far less evident, weighed heavily on him. This had struck him particularly in the fall of 1946 during the course of a visit by Edoardo Amaldi, his dear friend and collaborator in Rome.

  Fermi had forewarned Amaldi about the issue of secrecy months earlier, writing him that government funding for science carried “some very serious inconveniences. The most serious of all are military secrets. In this regard one hopes that a good part of the scientific results that are still kept secret can soon be published, but for the moment things are proceeding very slowly.”

  Despite the warning, their meeting was painful. Amaldi later reflected on what it had been like. “We used to talk and talk, and it was quite clear that after the war he could not say everything any more. With another person, it could have been different, but with Fermi it was terrible. I don’t blame Fermi—of course it was the situation.”

  Seeing the shackles of secrecy extended had annoyed Fermi, but the Cold War had come to Washington and a mood of fear prevailed. It did not help that Senator McMahon, the chair of Congress’s Joint Committee on Atomic Energy, was saying that war with Russia was inevitable and that the United States needed to “blow them off the face of the earth before they do that to us.”

  But could an H-bomb be built? Teller had proposed a scheme for the Super, but there were still numerous uncertainties. Hans Bethe, although opposing the Super, commented that nobody blamed Teller for thinking in 1946 that it might be feasible, but “he was blamed at Los Alamos for leading the Laboratory, and indeed the whole country, into an adventurous program on the basis of calculations which he himself must have known to have been very incomplete.”

  Teller’s forte, as Bethe knew from his wartime experience with him, was not elaborate modeling. But in the summer of 1950, the Super’s most ardent advocate had the help of three all-stars: the master calculator Fermi and the adroit mathematician Stan Ulam in Los Alamos, and the great John von Neumann in Princeton. At the end of the summer, all three concluded the bomb would not work. The prerequisite materials were scarce, the design faulty, and the will to proceed shaky.

  Fermi thought the issue had been laid to rest, but the next summer, on June 16 and 17, Oppenheimer asked him to join a meeting at Princeton’s Institute for Advanced Study, which he now directed. A summit conference of sorts, the meeting was intended to exchange information about a Super; it brought together key figures in the government, including AEC officials, and Los Alamos laboratory leaders. Attending as well were what the young physicist Ken Ford referred to as “the big three” consultants, Bethe, Fermi, and von Neumann. To everyone’s shock, Teller and Ulam had produced a new approach making it likely that a Super could be built. The prospects were so promising that those participating at the Princeton summit, including Fermi, endorsed the project. For Woods Marshall, who had berated her colleague so strongly about his former position, this stance was more in keeping with the Fermi she knew.

  In later explaining his reversal from the conclusions reached in October 1949, Oppenheimer said, “It is my judgment in these things that when you see something that is technically sweet, you go ahead and do it and you argue about what to do about it only after you have had your technical success.” The morality of building such weapons had not changed. Oppenheimer justified his change of mind on other grounds. The Korean War had increased the tension between the United States and the Soviet Union. In addition, the possibility of only the Soviets’ possessing thermonuclear weapons now seemed more ominous, more likely to upset the tenuous balance of terror. For Fermi as well, these were convincing reasons for changing his mind. Again and always the rational scientist, he felt that “once basic knowledge is acquired, any attempt at preventing its fruition would be as futile as hoping to stop the earth from revolving around the sun.”

  Both the United States and the Soviet Union did indeed pursue the development of the H-bomb. Los Alamos again swung into action, not at full throttle as for the Manhattan Project, but with a concentrated and intense effort. Fermi, who spent two months at Los Alamos during the summers of 1951, 1952, and 1953, continued to be an invaluable consultant on both developing the bomb and deciphering the results of Soviet explosions.

  The Americans conducted their first full test of the Super on November 1, 1952, on a Pacific atoll. Its yield was more than 450 times as great as the bomb dropped on Nagasaki. Soon after, on November 24, the Executive Director of the Joint Committee on Atomic Energy wrote to Fermi asking for his personal estimate of how much lead time the United States had over the USSR. Fermi answered on November 26, “It is impossible to make anything but a wild guess of the answer … My utterly uninformed guess is that it might take them some time between two and five years.” Again, Fermi’s formidable intuition (intuito formidabile) was correct. Although ten months afterward the Soviet Union—basically for propaganda purposes—exploded a bomb with some elements of fusion, it was not until three years later that they tested a bomb trul
y like the Super.

  38

  CIRCLING BACK

  Fermi had missed the October 5, 1949, General Advisory Committee (GAC) meeting and its arguments over weaponry. Instead, he was enjoying himself much more. He had arrived in Italy three weeks earlier, his first return to his homeland in the eleven years since he left in 1938.

  Laura had gone back to Europe earlier, in the summer of 1946, to see her brother, her two sisters, their families, and various friends. By that time, she had completed the multiple details associated with selling one house and buying another. The Fermis, when they left New Jersey for Chicago, had thought the relocation would be temporary. Little did they suspect that yet another move—to Los Alamos—would occur. From 1942 to 1946, they had rented their Leonia house to a family, the Ferralls, who regularly informed them about house problems. Several letters from Mr. Ferrall, often beginning with “Mrs. Ferrall has noticed,” recited a list of woes: the lack of screens, moth infestations, and dying trees. The American dream of home ownership, which Laura and Enrico had so avidly pursued as new immigrants, had its downsides. They sold the Leonia house in early June 1946, remembering one last thing. When they had bought the house in 1939, unsure of what the future might bring, the Fermis had placed some of their Nobel Prize money in a lead pipe to protect it from dampness. It was buried in the basement. They did not forget to dig the money up.

  The sale of the Leonia house coincided with the Fermis settling into their gracious new home in the Hyde Park neighborhood of the university. Laura had undertaken the exhausting task almost single-handed and in July 1946 was more than ready to reunite with her Italian relatives, while Enrico, Nella, and Judd stayed in the States. That summer Enrico was busy with work and, as had become customary, he was scheduled to spend several weeks in Los Alamos. Laura had arranged for temporary help in the Fermi household with the addition of Enrico’s devoted student Harold Agnew, his wife, and their two-year-old toddler. Fifteen-year-old Nella, according to Agnew, did most of the cooking that summer. Unlike her mother, whose privileged childhood had left the culinary arts to servants, Nella was showing her competence and self-sufficiency.