Making of the Atomic Bomb

by Richard Rhodes

  D pile went critical with a full 2,004-tube loading on December 17, 1944; B pile followed on December 28. Plutonium production in quantity had finally begun. Groves was enthusiastic enough at year’s end to report to George Marshall that he expected to have eighteen 5-kilogram plutonium bombs on hand in the second half of 1945.2110 “Looks like a race,” Conant noted for his history file on January 6, 1945, “to see whether a fat man or a thin man will be dropped first and whether the month will be July, August or September.”2111

  17

  The Evils of This Time

  The bombs James Bryant Conant speculated about early in 1945 were crude designs of uncertain yield. The previous October he had traveled out to Los Alamos to ascertain their prospects. To Vannevar Bush he reported that the gun method of detonation seemed “as nearly certain as any untried new procedure can be.”2112 The availability of a uranium gun bomb, which Los Alamos expected would explode with a force equivalent to about 10,000 tons of TNT, now depended only on the separation of sufficient U235. Implosion looked far more questionable; intensive work was just then getting under way following Oppenheimer’s August reorganization of the laboratory. Conant estimated the yield of the first implosion design, whether lensed or not, “as an order of magnitude only” at about 1,000 tons TNT equivalent. That was so relatively modest a result that he invited Bush to consider the gun bomb strategic and the implosion bomb tactical.

  For the past three years Bush and Conant had concentrated their efforts entirely on these first crude bombs. Now they were interested in improvements. During the summer of 1944, Conant says, on an earlier inspection trip to Los Alamos, he and Bush had found leisure and privacy to discuss “what the policy of the United States should be after the war was over.”2113 As a result they had sent Secretary of War Henry L. Stimson a joint memorandum on September 19 that independently raised some of the issues Niels Bohr had raised with Franklin Roosevelt in August, in particular that “the progress of this art and science is bound to be so rapid in the next five years in some countries that it would be extremely dangerous for this government to assume that by holding secret its present knowledge we should be secure.”2114, 2115 They did not see the bomb’s complementarity, but did see that whatever control arrangement the United States and Great Britain devised—they favored a treaty—would somehow have to include the Soviet Union; if the Soviets were not informed, as Bush told Conant, the exclusion would lead “to a very undesirable relationship indeed on the subject with Russia.”2116

  Roosevelt had returned from Hyde Park troubled that Felix Frankfurter and Bohr had somehow breached Manhattan Project security, Bush and perhaps Conant had talked to Bohr and the two administrators had submitted to Stimson at his request a more detailed proposal incorporating Bohr’s ideas. In doing so they had explicitly recommended that the United States sacrifice some portion of its national sovereignty in exchange for effective international control, understanding as they did so that they would have to answer vigorous opposition:

  In order to meet the unique situation created by the development of this new art we would propose that free interchange of all scientific information on this subject be established under the auspices of an international office deriving its power from whatever association of nations is developed at the close of the present war. We would propose further that as soon as practical the technical staff of this office be given free access in all countries not only to the scientific laboratories where such work is contained, but to the military establishments as well. We recognize that there will be great resistance to this measure, but believe the hazards to the future of the world are sufficiently great to warrant this attempt.2117

  But how great in fact were the hazards? That was something else Conant traveled to Los Alamos in October to find out. If the argument for allowing the nation’s military establishments to be inspected depended on the dangers of a thermonuclear explosive, it was speculative and therefore weak: the thermonuclear was still only an idea on paper that might not work. How much could fission weapons be improved? How much destructiveness of either kind might a bomber—or, as Bush and Conant briefed Stimson, “a robot plane or guided missile”—eventually visit upon the cities of the world?2118

  What Conant learned first of all was that others had already begun to ask the same questions. The technological imperative, the urge to improvement even if the objects to be improved are weapons of mass destruction, was already operating at Los Alamos. Under intense pressure to produce a first crude weapon in time to affect the outcome of the war, people had found occasion nevertheless to think about building a better bomb. Conant reported to Bush:

  By various methods that seem quite possible of development within six months after the first bomb is perfected, it should be possible to increase the efficiency . . . in which case the same amount of material would yield something like 24,000 Tons TNT equivalent. Further developments along this same line hold a possibility of producing a single bomb with such amounts of materials and such efficiencies as to run this figure up to several hundred thousand Tons TNT equivalent, or even perhaps a million Tons TNT equivalent. . . . All these possibilities reside only in perfecting the efficiency of the use of elements “25”[U235] and “49” [Pu239]. You will thus see that a considerable “super” bomb is in the offing quite apart from the use of other nuclear reactions.2119

  A million tons TNT equivalent was devastation indeed—the world war then raging would consume a total of about three million tons of explosives by its end—but Edward Teller, Conant found, had already dismissed such improvements as picayune:

  It seems that the possibility of inciting a thermonuclear reaction involving heavy hydrogen is somewhat less now than appeared at first sight two years ago. I heard an hour’s talk on this subject by the leading theoretical man at L.A. The most hopeful procedure is to use tritium (the radioactive isotope of hydrogen made in a pile) as a sort of booster in the reaction, the fission bomb being used as the detonator and the reaction involving the atoms of liquid deuterium being the prime explosive. Such a gadget should produce an explosive equivalent to 100,000,000 Tons of TNT, which in turn should produce Class B damage over an area of 3,000 square miles!

  This last real super bomb is probably at least as distant now as was the fission bomb when you and I first heard of the enterprise.

  The thermonuclear was something of a Rorschach test. If it could be made to work at all it was, like a fire, potentially unlimited; to build it larger you only piled on more heavy hydrogen. As Los Alamos paid less attention to Teller’s Super his projection of its destructive potential grew moregrandiose.

  Robert Oppenheimer also committed himself at that time to exploring the thermonuclear—after the war was won—in a letter to Richard Tolman on September 20, 1944. “I should like,” he emphasized, “ . . . to put in writing at an early date the recommendation that the subject of initiating violent thermonuclear reactions be pursued with vigor and diligence, and promptly.” A way station on the road to a full-scale thermonuclear might be a boosted fission bomb with a small charge of heavy hydrogen confined possibly within the core of an implosion device:

  In this connection I should like to point out that [fission] gadgets of reasonable efficiency and suitable design can almost certainly induct significant thermonuclear reactions in deuterium even under conditions where these reactions are not self-sustaining. . . . It is not at all clear whether we shall actually make this development during the present project, but it is of great importance that such . . . gadgets form an experimentally possible transition from a simple gadget to the super and thus open the possibility of a not purely theoretical approach to the latter.2120

  (In fact not deuterium but tritium proved to be the necessary ingredient of a boosted fission bomb, and such weapons were not developed until long after the end of the war.)

  Alluding then to the larger consequences that Bohr had revealed, Oppenheimer emphasized once more the urgency he attached to the pursuit of an H-bomb: “
In general, not only for the scientific but also for the political evaluation of the possibilities of our project, the critical, prompt, and effective exploration of the extent to which energy can be released by thermonuclear reactions is clearly of profound importance.”

  Working against the clock to build weapons that might end a long and bloody war strained life at Los Alamos but also heightened it.2121 “I always pitied our Army doctors for their thankless job,” comments Laura Fermi:2122

  They had prepared for the emergencies of the battlefields, and they were faced instead with a high-strung bunch of men, women, and children. Highstrung because altitude affected us, because our men worked long hours under unrelenting pressure; high-strung because we were too many of a kind, too close to one another, too unavoidable even during relaxation hours, and we were all [as Groves had warned his officers not entirely tongue-in-cheek] crackpots; high-strung because we felt powerless under strange circumstances, irked by minor annoyances that we blamed on the Army and that drove us to unreasonable and pointless rebellion.

  They made the best of it. Mici Teller waged pointed rebellion saving the backyard trees to preserve a playground for her son. “I told the soldier in his big plow to leave me please the trees here,” one of her friends remembers her recounting, “so Paul could have shade but he said, ‘I got orders to level off everything so we can plant it,’ which made no sense as it was planted by wild nature and suits me better than dust. The soldier left, but was back next day and insisted he had more orders ‘to finish this neck of the woods.’ So I called all the ladies to the danger and we put chairs under the trees and sat on them.2123 So what could he do? He shook his head and went away and has not come again.” Contrariwise, to clear a ski area on the hill to the west of the mesa, George Kistiakowsky wrapped the trees with half-necklaces of plastic explosive and thus noisily but efficiently cut them down. “Then we scrounged equipment to build a rope tow and it became a nice little ski slope,” he recalls.2124

  The Fermis moved to Los Alamos in September 1944 and requested one of the less coveted fourplex apartments rather than the Ranch School faculty cottage that had been prepared for them, to make a point about social snobbery. The Peierls, Rudolf and energetic Genia—Otto Frisch’s dish-drying coach in Birmingham—lived below. The mix of birthplaces and citizenships was typical of the Hill: Peierls a German Jew, his wife a Russian, both with British citizenship; Laura Fermi still nostalgic for Rome but she and her husband new American citizens as of July. “Oppie has whistled,” Fermi would announce with a yawn when the morning siren sounded. “It is time to get up.”2125 The Italian laureate directed a new operation, F (for Fermi) Division, a catchall designed to take advantage of his versatility as both theoretician and experimentalist. One of the groups he caught was Teller’s. “That young man has imagination,” the forty-three-year-old Italian emigré told his wife drolly of the thirty-six-year-old Hungarian. “Should he take full advantage of his inventiveness, he will go a long way.”2126 Teller stayed up late at night working out ideas and playing the piano and hardly ever appeared in the Tech Area before late morning.

  “Parties,” remembers Fuze Development group leader Robert Brode’s articulate wife Bernice, “both big and brassy and small and cheerful, were an integral part of mesa life. It was a poor Saturday night that some large affair was not scheduled, and there were usually several of them. . . . On [Saturday nights] we raised whoopie, on Sundays we took trips, the rest of the week we worked.”2127 Single men and women sponsored dorm parties fueled with tanks of punch made potent with mixed liquors and pure Tech Area grain alcohol and invited wall-to-wall crowds. The singles removed all the furniture from their dormitory common rooms to make areas for dancing and by unwritten rule kept their upstairs doors open through the night.

  Square dancing evolved as a natural Saturday evening activity in that Southwestern setting. (“Everybody was wearing Western clothes—jeans, boots, parkas,” Stanislaw Ulam’s French wife Françoise remembers noticing with surprise when she and her husband arrived on the Hill. “There was a feeling of mountain resort, in addition to army camp.”2128) The dances were first held in Deke Parsons’ living room, then the theater, then Fuller Lodge, finally expanding to crowd the large mess hall. Eventually even the Fermis attended with their daughter Nella to learn the vigorous reels. Long after mother and daughter had been persuaded from the sidelines Fermi sat unbudging, mentally working out the steps. When he was ready he asked Bernice Brode, one of the leaders, to be his partner. “He offered to be head couple, which I thought most unwise for his first venture, but I couldn’t do anything about it and the music began. He led me out on the exact beat, knew exactly each move to make and when. He never made a mistake, then or thereafter, but I wouldn’t say he enjoyed himself. . . . He [danced] with his brains instead of his feet.”2129

  Theater sometimes supplied a Saturday alternative. At a performance of Arsenic and Old Lace Robert Oppenheimer surprised and delighted the audience by appearing powdered sepulchrally white with flour as the first of the crowd of corpses emerging from the cellar in the last act. Donald Flanders, tall and bearded, known as Moll, Computation group leader in the Theoretical Division, wrote a comic ballet, Sacre du Mesa, set to George Gershwin music. Despite his beard and his lack of ballet training Flanders danced the part of General Groves. Samuel Allison’s son Keith appeared as Oppenheimer, dancing on a large table wearing suitably casual clothes and a pork-pie hat. “The main stage prop,” Bernice Brode notes, “was a mechanical brain with flashing lights and noisy bangs and sputters, which did consistently wrong calculations, for example, 2 + 2 = 5. In the grand but hectic finale, the wrong calculations were revealed as the real sacred mystery of the mesa.”2130

  Kistiakowsky preferred less formally intellectual entertainment:

  I played a lot of poker with important people like Johnny Von Neumann, Stan Ulam, etc. . . . When I came to Los Alamos I discovered that these people didn’t know how to play poker and offered to teach them. At the end of the evening they got annoyed occasionally when we added up the chips. I used to point out that if they had tried to learn violin playing, it would cost them even more per hour. Unfortunately, before the end of the war, these great theoretical minds caught on to poker and the evening’s accounts became less attractive from my point of view.2131

  And Robert Wilson, Cyclotron Program group leader, who served on the advisory Town Council, discovered even more elemental activities on the Hill despite security screening before employment and roving military police:

  Of the many problems that were presented to us during my term of office, the most memorable was when the M.P.’s who guarded the site chose to place one of our women’s dorms off-limits. They recommended that we close the dorm and dismiss the occupants. A tearful group of young ladies appeared before us to argue to the contrary. Supporting them, a determined group of bachelors argued even more persuasively against closing the dorm. It seems that the girls had been doing a flourishing business of requiting the basic needs of our young men, and at a price.2132 All understandable to the army until disease reared its ugly head, hence their interference. By the time we got that matter straightened out—and we did decide to continue it—I was a considerably more learned physicist than I had intended to be a few years earlier when going into physics was not all that different from taking the cloth.

  Married or single, the occupants of Post Office Box 1663 were young and healthy; they produced so many babies that Groves ordered either the reservation commander or the laboratory director—both versions of the story survive—to staunch the flood. Oppenheimer, if Oppenheimer it was, refused the duty. With justification: his wife Kitty bore him a second child, a daughter, Katherine, called Toni, on December 7, 1944. So many people wanted to see the boss’s baby that the hospital identified the crib with a sign and lines formed to file past the nursery window.

  Crowded together behind a fence, Hill families worried about epidemic disease. A pet dog that had bitten several ch
ildren turned up rabid and pet owners debated angrily with parents about which category of dependent should be kept on a leash. More frightening was the sudden death of a young chemist, a group leader’s wife, from an unidentified form of paralysis. Fearing an outbreak of poliomyelitis, doctors closed the schools, put Santa Fe off limits and ordered all children indoors.

  No new cases appeared, the danger abated with the continuation of cold weather and work and play resumed. “I don’t think I shall ever again live in a community where so many brains were,” comments Edwin McMillan’s wife Elsie, Ernest Lawrence’s sister-in-law, “nor shall I ever live in a community so confined that visitors expected us to fight with each other. We didn’t have telephones, we didn’t have the bright lights, but I don’t think I shall ever live in a community that had such deep roots of cooperation and friendship.”2133

  Some reserved Sundays for church and hobbies; others devoted the day to outings. The Oppenheimers maintained magnificent riding horses and rode regularly on Sunday morning but only once in three years found time for an overnight excursion. Kistiakowsky bought one of Oppenheimer’s quarter horses and refreshed himself trailing in the mountains after his late Saturday poker nights; the Army stabled the private animals along with the remuda it kept for the mounted MP’s who patrolled the mesa fences. Emilio Segrè found excellent fly-fishing. “The streams are full of big trouts,” he announced happily to newcomers. “All you have to do is throw in a line and they bite you, even if you are shouting.”2134 Fermi took up angling, says Segrè, “but he went about it in a peculiar way.2135 He had tackle different from what anyone else used for trout fishing, and he developed theories about the way fish should behave. When these were not substantiated by experiment, he showed an obstinacy that would have been ruinous in science.” Fermi insisted on fishing for trout with worms, arguing that the condemned creatures should be offered an authentic final meal, not the dry flies of tradition. Segrè made a point of reviewing the subtleties of trout fishing with his old friend. “Oh, I see, Emilio,” Fermi eventually countered, “it is a battle of wits.”2136