Authors: Jennet Conant
As their second Christmas on the Hill approached, women began descending on Santa Fe in a fruitless hunt for goods that had long ago disappeared off the shelves. Dorothy was deluged with requests for skates and skiis, baby clothes and anything that might pass as a maternity dress. The rapid population growth on the Hill had strained the resources of the little town, and the shops were out of everything. Because of wartime rationing, the amount of goods the local stores were allowed to order was based on the tiny population of Santa Fe alone, and not on the needs of a burgeoning mountaintop city that for all intents and purposes did not exist. There were no new boots to be had, no cribs, no electric ovens, no tires for the car—new, used, or even patched and tread-worn. None. The town was tapped out. There was nothing to do but try to order things from a store back in civilization and have it shipped at considerable expense, or wait and hope the war would soon be over and they would be allowed to leave.
People haunted Dorothy’s office at 109 East Palace in hopes of snagging the first coveted copies of the Sears Roebuck catalog. When they returned to the post, they would run down the street yelling, and everyone in earshot would gather around for a look. Since nearly all personal shopping had to be done by mail, they would pore over the pages, nearly swooning at the wealth of merchandise on display. For some mysterious reason the Montgomery Ward catalog was freely available, while others were so much in demand at Los Alamos that one company dispatched a stern note: “Sir: We don’t know what you are doing to our catalogs. We have sent more than 100 catalogs to this address and will send no more.” The treasured volumes, thick as telephone books, were jealously guarded and passed along from family to family until they were dog-eared and torn. On one occasion the Tech Area operator, by request, sent a pointed message over the laboratory loudspeaker system: “Attention, please. Will the person who took the Sears Roebuck catalog from Harold Agnew’s room please return it immediately. Repeat—immediately!”
Despite Groves’ objections, Los Alamos’s baby boom continued unabated. One after another, the scientists’ wives announced they were pregnant. Oppenheimers assistant, Priscilla Greene, was expecting, as were Elsie McMillan, Beverly Agnew, and Rose Bethe. Phyllis Fisher, the wife of the young physicist Leon Fisher, was reassured to learn that a whole group of her friends would be “waddling around the mesa together,” as though these real-life babies-to-be would somehow counterbalance the “awesome baby” that the project would give birth to in a few months. “It seemed to me that we were all striving to maintain the fiction that somehow life could be normal in that very abnormal setting,” she observed, adding, “Perhaps that was a vain hope.”
On December 7, 1944, the birth of Katherine Oppenheimer was announced, and the whole town shared in their director’s pride and delight. Everyone was in the habit of dropping by the hospital to see the newborns, and friends often stood on packing crates outside the maternity ward’s window for a peek and a chat. So many people wanted to see the boss’s baby daughter that the hospital staff was finally forced to hang a hand-lettered sign that read
OPPENHEIMER
over her crib, and visitors’ hours were suspended to make way for the steady stream of well-wishers who filed by for days. Undeterred by the bad weather, Dorothy drove up with chains on her tires just to see the new addition to Box 1663. “Little Toni,” as she was called, had been born into such great secrecy that when Dorothy filled out her birth certificate, she could only list the benign rural post office box in Sandoval County as the home address. She brought Kevin with her; and as it had been his birthday the day before, she had arranged a special treat. Dorothy had worked out a deal with the sergeant who was the head of the post motor pool “to borrow” one of the heavy, four-wheel-drive army vehicles for the fifteen-year-old to take for a spin. “The snow must have been two feet deep,” recalled Kevin. “I remember driving up and down the main street, and I thought I had died and gone to heaven.”
It was a madly busy holiday season. There was something in the air—no one was in the mood for quiet reflection. People threw themselves into the festivities with abandon, singing, drinking, and dancing until dawn. There were endless rounds of parties, and vats of heavily spiked eggnog were consumed. A group of families banded together and organized a big New Years Eve bash at Fuller Lodge, and at the stroke of midnight, they rang in 1945 with the old Ranch School bell used to call the boys to meals. It was such a memorable evening that they all agreed it should become a mesa tradition—that is, if they were all still captive there in twelve months’ time. Even as they joined hands and broke into a rousing rendition of “Auld Lang Syne,” they heard the quaintly nostalgic words as they never had before, and sang their hearts out, not knowing what the coming year would bring.
FIFTEEN
Playing with Fire
T
HERE WERE MANY
lighthearted moments that winter, but while relieving the boredom of people’s regimented lives, those good times did nothing to dispel the deepening chill that had settled over the community. The construction of the Trinity site had been completed, and as the laboratory moved into the final production and testing phase, a growing sense of foreboding tugged at everyone’s thoughts. In February, Groves swept in for a conference, and they came to the decision that the time had come to “freeze” the implosion program and focus their efforts on one of the several designs they had been considering. Oppenheimer had set July 20, 1945, as the target date for having both bombs ready. He drew up a schedule and methodically drove the divisions forward, checking off stages as they were completed. The men toiled at a frenzied pace to prepare for the test shot. Even at parties they never seemed to unwind, but gathered in tight knots and discussed complex equations in low, urgent voices.
The fissionable materials—plutonium and uranium 235—were now coming off the production lines in large quantities, and the physicists were faced with the long, arduous task of converting them into metal, casting them, and finally delivering the explosive devices to be used in the bombs. At the Omega site, an operations lab set up in a canyon well removed from the crowded mesa, Don Kerst and Fermi had just about completed work on what was called the “Water Boiler,” code for a small nuclear reactor, and were ready to begin preliminary tests to measure the critical mass of the uranium 235 bomb. As the critical assembly tests progressed, Fermi grew increasingly nervous and kept finding excuses to take his crew on long hikes in the mountains.
All of the work at the Omega site focused on preparing experiments that could help reveal the performance of the bomb. But as Segrè recalled, a nuclear explosion was such a completely new and complex event—with mechanical, thermal, optical, chemical, and nuclear aspects—that in some cases they did not even know the order of magnitude of the quantities to be measured, and consequently needed equipment that could cover a vast range. The physicists were dealing with a host of unknowns, under extremely unusual conditions, and, as Segrè noted, this “worried everyone”:
There was obviously plenty to measure; the energy released was the overall central parameter, which could be inferred in many different, independent ways. Each measurement had its particular difficulties, but one was common to all of them: the experiment could not be repeated. If something failed, there was no second chance.
During this period, Otto Frisch proposed an extremely bold experiment that would simulate bomb conditions and go, as he put it, “as near as we could possibly go towards starting an atomic explosion without actually being blown up,” a risky procedure that Feynman likened, with false levity, to “tickling the tail of a sleeping dragon.” Nonetheless, Frisch managed to convince Oppenheimer and the senior physicists that with the proper precautions, the “Dragon Experiment” could be conducted with complete safety.
Once his experiment was given the green light, the experimental setup was completed in a few weeks, with Frisch as group leader. His idea consisted of using some of the U-235 to assemble an explosive device, but leaving a sizable hole, so that when the missing core of enriched uranium hydride was dropped into the ring, it would cause the material to go supercritical for a fraction of a second. The core would immediately be pulled back and could subsequently be reinserted to enable more measurements. This would allow them, through repeated efforts, to learn exactly how much uranium would be needed for Little Boy.
Everything went as planned. “When the core was dropped through the hole,” recalled Frisch, “we got a large burst of neutrons and a temperature rise of several degrees in that very short split second during which the chain reaction proceeded as a sort of stifled explosion.” There was always the danger of a runaway reaction. They were all aware that the assembly could become critical in no time, and that even a minor mistake could result in death. They devised a reliable system of safety checks and made a strict rule that no one could work alone, so that someone would always be monitoring the equipment and careless accidents could be avoided.
Despite all his precautions, however, Frisch nearly made a fatal mistake while working on an unusual assembly he dubbed “Lady Godiva.” He and his assistant were standing by the neutron-counting equipment when they both saw the red signal lamps start blinking faster and faster. His assistant, a young graduate student, panicked and pulled the plug on the meter. Frisch yelled out, “Do put the meter back, I am about to go critical.” Out of the corner of his eye, he saw the signal lamps had stopped flickering and were now glowing red. Thinking quickly, he removed some of the blocks of uranium compound he had just added and the lights began flickering again as the meter slowed. “It was clear to me what had happened,” he recalled. “By leaning forward I had reflected some neutrons back into Lady Godiva and thus caused her to become critical.” He had not felt anything, but after carefully completing the experiment, he checked the radioactivity counter and found that he had received a rather large dose, though within the lab’s permissible parameters. Had he hesitated for even two seconds before removing the fissionable material, the dose would have been lethal.
Even after his close call, Frisch continued to work with critical masses, maintaining that the danger was largely psychological: “Assembling a mass of uranium-235 was something we completely understood, and as long as we hadn’t reached the critical amount—when the chain reaction began to grow spontaneously—the assembly was completely harmless.” Overeagerness and haste were the real threats, and a bright young physicist who pushed too hard for results would pay the price. They were all working under enormous pressure. The uranium had to be returned shortly to be turned into metal and assembled into a real atom bomb, so they worked at a frantic pace to complete their experiments, putting in seventeen-hour days and snatching a few hours sleep from dawn till mid-morning.
Progress was being made in other areas. James Conant visited Los Alamos again to obtain a firsthand report on the “Christy bomb,” project slang for the ingenious proposal made by Bob Christy, one of Oppie’s former students, to simplify the design of the plutonium bomb. His modification promised to save the physicists an enormous amount of work. After the meeting, Oppenheimer and the others left, leaving only Conant and Teller in the room, sitting together in contemplative silence for a few moments. Then Conant muttered, more to himself than anyone else, “This is the first time I really thought it would work.” Teller stared at him. “That was the first indication I had of how little confidence those in the highest scientific quarters had in our work,” he recalled. “I was slightly shocked.”
There were still too many unknowns and uncertainties, and Oppenheimer decided they needed to have some sort of dry run. They had to have at least a working idea of the conditions they could expect at ground zero, to check their equipment and correct for any weaknesses in their plans. The idea was to explode one hundred tons of conventional explosives at the Trinity site and then perform all the same measurements they would later make on the atomic bomb. Although TNT could only approximate the atom bomb’s effect—for example, it did not emit neutrons or gamma rays—it would at least give them a chance to study the blast effects of a huge explosion and begin to calibrate their instruments for the final shot. This was the best they could do without wasting any of their valuable nuclear explosives.
Bainbridge was asked to hastily organize the dress rehearsal. By March, Project Trinity was formalized, and Oppenheimer tapped Bainbridge, a three-year veteran of the MIT Rad Lab, to be director of the test program. Oppie appointed Johnny Williams as deputy director to help oversee the construction crews and make sure the scientific facilities and shelters conformed to the project’s needs and were completed on time. Dozens of physicists were called away from their divisions and assigned to work on experiments designed to obtain measurements on the blast, heat, and radiation effects of a nuclear explosion. He formed the Cowpuncher Committee to “ride herd” on the implosion program and make sure they met their deadline. As Bainbridge observed, “The great push to solve the problems of the implosion method had meant that only a small amount of staff time, shop time, and money could be spent in preparation for a test.” Every decision they made had to be considered on the basis of the time scale for completion. There would be no delay of the implosion test.
As the secrecy intensified, the already high-strung character of the mesa altered perceptibly. The military personnel, feeling more useless and beside the point than ever, were increasingly irritable and impatient. The scientists, dashing between the mesa and the remote test site, were harassed and exhausted. Wives who had been close friends became guarded about their husbands’ new responsibilities and whereabouts, and no longer felt free to confide their mutual worries. For the first time since they had arrived at Los Alamos, the wives could not rely on one another to help defuse the tension, and their fears and anxieties hung heavily in the air. “The wives couldn’t talk to each other,” said Dorothy, who had by then gleaned the purpose of “the gadget,” but was in no position to enlighten anyone else. “Each didn’t know how much the other knew about what their husbands were doing.”