A last-minute call from Jean Tatlock—who continued to lean upon Oppie at moments of psychological distress—went unanswered.87
Another friend to whom Oppie bid adieux was Haakon Chevalier, who would subsequently describe their leave-taking elegiacally, as evoking “a ‘Cherry Orchard’ mood.”88 Chevalier remembered Oppenheimer expressing the fear that the Germans might win the war. “But perhaps we can think up a few tricks,” Oppie added, brightening.89 Barbara Chevalier had figured out that the couple must be headed for the mountains, since Kitty was buying woolen clothes for Peter. Oppie would later recall only that he had complained to Chevalier about his security clearance being held up.90
Their political coffee klatch had held its final meeting the previous spring, before disbanding on account of the war; Oppenheimer had missed this last gathering, having been summoned to Chicago by Compton.91
Chevalier, too, was adjusting to changes brought about by the war. He had long been aware that his fortunes at the university were on the wane. His department chairman had informed him that he should look for a teaching job elsewhere. But Chevalier, like Oppenheimer, was also feeling guilty to be sitting out the war. A week before he bid farewell to Oppie, Haakon had written to his son, Jacques, an undergraduate at Yale:
We are such a small part of this big, world-shaking revolution that we may well feel discouraged. But the world does move, however slowly, and perhaps, even in our small way, we shall be able to play an effective role. It is ironic for me to feel how little I am doing for this war while I imagine the possibility of doing so much. I certainly don’t intend to resign myself to remaining a bystander, but as yet I am not reconciled to becoming a small cog in the monster machine, where my hands would be tied and where, though I would be an integral part of the “war effort” I might have fewer possibilities of doing some [sic] effective within my feeble competence than if I retain, for the time being, some freedom of action.*92
PART TWO
INSIDE THE WIRE
We shall all be one large family doing work inside the wire.
—Robert Oppenheimer, Los Alamos, 1943
5
ENORMOZ
OPPENHEIMER HAD BARELY unpacked at Los Alamos when Underhill arrived by train on his first inspection trip. The regents’ representative was still hoping to learn what he and Sproul had committed the university to do. Oppie, however, did his best to frustrate Underhill’s investigation. Wedged in the backseat of an army sedan between Oppenheimer and Priscilla Duffield, Oppie’s secretary at the lab, Underhill was driven quickly up the rough and dusty road that led to the mesa before being taken back to Santa Fe. The lab’s director volunteered no useful information about the project during the drive.
Undeterred, Underhill would make monthly visits to Los Alamos for the duration of the war. As ever, the regents’ representative remained the soul of discretion. To discourage questions from curious strangers, Underhill told everyone he met on the east-bound train that he was a farmer from Manhattan, Kansas—a town the railroad bypassed. On the return trip, Underhill introduced himself as a California olive farmer, knowing that there were only a few places in the state where olives were grown. He memorized the market price of oats and alfalfa and read a book on olive tree diseases so that his cover would be all the more believable.1
With a university attorney in tow, Underhill headed east again the following month to work out final arrangements with the army. On April 20, 1943, he signed Contract 36 on behalf of the regents, for administrating Los Alamos. Six weeks later, Underhill was back in Groves’s suite at the Biltmore to sign Contract 48, for expenses related to the Calutrons and other army projects at the Rad Lab. Both agreements were dated January 1, 1943, to account for the work already done by the university.2
At Los Alamos, work on the bomb was already under way. Oppenheimer assigned Serber the job of briefing the dozens of scientists arriving from colleges and universities around the country. In early April, the recruits assembled in the uncompleted library of T Building, future offices for the theoretical physicists. In a series of five lectures given over the next two weeks, Serber laid out the current state of knowledge about the atomic bomb, including what had been learned since the Berkeley summer seminar.
Eager to dispel any illusions about the nature of the task, Serber emphasized at the outset that the “object of the project is to produce a practical military weapon.”3 Cautioned about using the word bomb while uncleared construction workers were still crawling around in the ceiling above his head, Serber began calling it the “gadget” instead. Taking the last digit of the atomic number, 94, and the last digit of the atomic weight, 239, he referred to plutonium as “49”; uranium was simply “U” or “the material.”
The first gadget discussed by Serber was the so-called gun, the earliest image of the bomb going as far back as the M.A.U.D. report. In a gun-type bomb, two subcritical pieces of U-235 or plutonium would be “assembled” by being fired into each other by a cannon. Theoretically, the 3,000-foot-a-second acceleration would drive the pieces together into a supercritical mass before stray neutrons could predetonate it. Serber named the long, skinny device the “Thin Man,” after the character in the popular film starring William Powell and Myrna Loy.4
An alternative design, more complex but more efficient—if it worked—had been dubbed the “Introvert” by Caltech’s Richard Tolman, whom Groves had sent to Los Alamos as a kind of inspector general.5 The weapon that Tolman and Serber imagined would surround a
