Pandora's Keepers (18 page)

Among many things they discussed was a far-fetched idea that Teller had hatched with Fermi the year before: could the explosion
of an atomic bomb heat the nuclei of heavy hydrogen (deuterium) enough to begin thermonuclear fusion? Such a bomb would be
infinitely more destructive than even a fission bomb. Out of curiosity, Oppenheimer vigorously pursued the idea of a “superbomb”
based on thermonuclear fusion. He and the other conferees made extensive calculations, which were disappointing—such a weapon
apparently could not be made. Yet the concept of a “superbomb” would remain a nagging challenge to Teller’s restless mind,
one that he took secretly to heart and would nurse for years to come.

The Berkeley conference was the first and only time Oppenheimer and Teller discussed physics with the shared purpose that
they enjoyed with other colleagues throughout their lives. “We had a few days of quite violent discussion by which we even
learned something,” Teller reported to Fermi at the end of their deliberations.
⁷⁰
Teller attributed the progress they had made to Oppenheimer. It was a pleasant surprise for Teller, who had first glimpsed
Oppenheimer four years earlier at a physics colloquium in Berkeley. After the colloquium Oppenheimer had taken Teller to dinner
at a Mexican restaurant in San Francisco. Teller had found the dishes spicy and Oppenheimer overwhelming, even intimidating.

Now, during the summer conference, Oppenheimer and his wife, Kitty, invited Teller and his wife, Mici, to dinner at their
home on Eagle Hill. The other guests at dinner that night were Haakon Chevalier and his wife, Barbara. Teller brought along
a record of his favorite Mozart piano concerto as a hospitality gift, which he felt Oppenheimer found uninteresting. His feeling
was subtly reinforced by
mikosh
, a cultural inferiority complex that Teller, a Hungarian Jew, felt toward Oppenheimer, a descendant of German Jews. Teller
had imagined or actually experienced this superior feeling of Germans toward Hungarians as a graduate student at Leipzig and
Göttingen and was sensitive—perhaps hypersensitive—to it. Oppenheimer may have been born in New York, but to Teller he represented
the Germany that had always been out of reach, even to the son of a respected and socially responsible Hungarian lawyer. That
they were both Jews made little difference, since in Oppenheimer Teller saw a Jewish elite far above his orbit, an elite whose
riches and status commanded respect and opened doors. Oppenheimer, unlike Teller, did not hail from the trembling class.

Feeding the electricity between Oppenheimer and Teller were their differing personalities and temperaments. Teller was gregarious
and extroverted, Oppenheimer was shy and introverted. However, both were arrogant, ambitious, charismatic, and intense. Both
wanted to be “top dog” and resented those whom they thought were rivals. Running through their relationship from the beginning
was an unstated but unmistakable—and inescapable—tension. Their fates were intertwined, although each barely sensed it at
the time.

At the end of the Berkeley conference, Oppenheimer, Teller, and Bethe concluded that an atomic bomb
could
be made, but it would require an immense scientific and engineering effort. They now realized the sheer scale and complexity
of what was involved, and how much of themselves would be required to make the bomb a reality.

The design and construction of the bomb would be a major task, but until enough plutonium could be produced, bomb design was
of secondary importance. The task of constructing a chain-reacting pile that would yield plutonium fell to Fermi, with help
from Szilard. One of the biggest problems was the impurity of uranium and graphite supplies. Szilard immediately set about
convincing the main U.S. graphite producer, Union Carbon and Carbide, to produce very large quantities of incredibly pure
graphite. He also had Compton call Westinghouse and ask, “How soon can Westinghouse supply three tons of pure uranium?” Compton
heard a gagging sound at the other end of the line, but the firm’s response was positive. Using uranium ore spirited out of
the Belgian Congo at the time of the fall of France and sent to a warehouse in New York, Westinghouse stepped up purification
from eight ounces a day to over five hundred pounds, and by November 1942 had delivered the three tons.

Fermi worked countless hours with younger scientists planning the pile and calculating the uranium and graphite needed. He
was not above doing tedious work himself. “Fermi was doing it with all the rest of us,” said a young physicist who helped
construct the pile. “When he was on shift, he was on shift—the same as the rest of us.”
⁷¹
It made him a beloved figure. He found release from the strain and long hours of work by swimming on hot summer afternoons
in the choppy waters of Lake Michigan off the huge breakwater rocks from the Fifty-fifth Street Promontory to the Sixty-eighth
Street Pier. He did a funny dog paddle but had amazing stamina.

The site of the pile’s construction was a large squash court beneath the west stands of Stagg Field, whose masonry facade
and crenellated towers facing Ellis Avenue between East Fifty-sixth and Fifty-seventh Streets a block north of Eckart Hall
concealed a warren of indoor courts and locker rooms. Scarcely anyone had come this way since the university abandoned participation
in intercollegiate football several years before. But here, on November 7, 1942, assembly of the world’s first nuclear reactor—called
Chicago Pile One (CP-1)—began. There was nothing ceremonial about it. A couple of physicists finished sweeping the floor of
a square-shaped gray rubber balloon that would enclose the pile. The huge balloon was hung from the ceiling, with one side
left open; then, in the center of the floor, a layer of graphite bricks was placed in a circle and braced by a wooden frame.
Somebody jokingly shouted, “Well, Enrico, why don’t you lay the cornerstone?”
⁷²
Fermi grabbed a graphite brick and placed it with a grin.

The concept was to build a lattice of graphite bricks, interspersing plugs of uranium oxide until it was big enough to maintain
a critical reaction. There were no plans or blueprints, just layer after layer of dark, slippery graphite bricks four inches
wide and deep and sixteen inches long and uranium plugs weighing six pounds each and spaced eight inches apart. A layer of
solid graphite blocks alternated with a layer of graphite blocks filled with uranium plugs. The pile had an odd shape. The
base was square like a windowless brick house, but the top was tapered in the form of a roughly flattened sphere. Before the
work was finished, 45,000 graphite bricks with uranium plugs were stacked into a sphere twenty-five feet wide at its midpoint
and twenty feet high enclosed within the square rubber balloon.

Fermi directed assembly of the pile from his office in Eckart Hall and then from the balcony of the squash court as the work
progressed. Young physicists laying graphite bricks carefully lined up slots for control-rod channels of neutron-absorbing
cadmium that passed at various points through the pile. As it grew, layer by dusty layer, they assembled wooden scaffolding
to stand on and ran loads of bricks up to the working surface on a portable elevator. “It was hard work, and it was dirty,”
said one who helped build the pile. “You’d look like you came out of a Kentucky coal mine at the end of a shift.”
⁷³
Fine black powder covered faces, lab coats, shirts, trousers, walls, flooring—everything. A dark haze dispersed light in
the floodlit air. The only white to be seen was the gleam of teeth. “The people were all black with red eyes peering out,”
recalled an eyewitness. “It was like a scene from hell. It was a different world.”
⁷⁴

As the pile neared completion, Compton had to decide whether to bring the pile to critical mass (initiating a self-sustaining
chain reaction) right in the middle of a crowded city. “We did not see how a true nuclear explosion, such as that of an atomic
bomb, could possibly occur,” Compton later wrote with more calm and certainty than he probably felt at the time. “But the
amount of potentially radioactive material present in the pile would be enormous and anything that would cause excessive radiation
in such a location would be intolerable.”
⁷⁵
He asked Fermi about the probability of controlling a chain reaction; Fermi said it could be controlled.

Compton gave Fermi permission to go ahead, but he chose not to inform University of Chicago president Robert Maynard Hutchins.
“The only answer he could have given would have been—no. And this answer would have been wrong. So I assumed the responsibility
myself.”
⁷⁶
If the number of neutrons generated became too large, the pile would heat up and melt down. No one, including Fermi, could
be sure that a meltdown would not occur and take all Chicago, or even Illinois, with it, so two young physicists volunteered
to form a “suicide squad.” The two would stand on scaffolding overlooking the pile with buckets of liquid cadmium in their
grip. If all other controls failed and the pile started to melt down, they would hurl the cadmium on it.

As the pile grew larger, the neutron strength became stronger, so it became easier to predict when it could be made to go
critical. When the fifty-seventh layer of bricks was completed on the night of December first, the work was halted. All the
control rods but one were removed and the neutron count was taken. It was clear from the count that once the remaining rod
was removed, the pile would go critical. Since it was late, the control rods were put back in and locked up for the night.
The pile contained 771,000 pounds of graphite and 12,400 pounds of uranium, assembled at the cost of $1.5 million. Fermi was
confident that the next day’s experiment would be a success: he would start—and control—a chain reaction. And if he could
not? asked one of his colleagues. “I will walk away—leisurely,” he breezily answered.
⁷⁷

Szilard also doubted that the pile would run out of control, but he brooded nonetheless and seemed withdrawn. That night he
walked to Culver Hall, where a psychologist whom he knew often worked late. “Come to dinner with me,” Szilard said, and the
psychologist, who enjoyed Szilard’s speculative conversations, accepted. Szilard had already eaten but would have a second
dinner “just in case.” “Just in case what?” asked the psychologist. “In case an important experiment doesn’t succeed,” answered
Szilard.
⁷⁸

December 2, 1942, dawned brutally cold. Ellis Avenue was strangely empty. Inside under the west stands of Stagg Field it was
as cold as it was outside. Fermi put on his gray lab coat, which normally matched the color of his hazel eyes but now was
black with graphite, entered the squash court, and went up to the balcony. Compton took his place next to Fermi. The balcony
was now filled with control equipment glowing and radiating some grateful heat. It was unusually quiet in the vast, drafty
room. Only the silhouettes of half a dozen physicists could be seen around the pile, which squatted black and menacing, watched
by a roomful of hopeful and nervous eyes.

At 9:45
A.M.
Fermi ordered all but one of the control rods withdrawn from the pile. The last control rod would be withdrawn by measured
increments. Everyone stopped talking; only Fermi’s voice could be heard in the silence. He instructed a young physicist to
move it out halfway. The pile was still below critical mass. Fermi’s fingers moved quickly over his small slide rule as his
eyes checked the monitoring equipment. As usual, he looked completely self-confident. He had thoroughly prepared every detail
of the experiment and was going to make a good show of it. He wanted to demonstrate how completely he understood the process.
He wanted to prove that his predictions were accurate. Not only was he going to a witness a new phenomenon, he was going to
be its master. “Fermi was playing this like an orchestra leader,” said a young physicist who was there.
⁷⁹

He ordered the final control rod moved out another six inches. The tension in the room mounted as the Geiger counters registering
neutrons from the pile began to click faster and faster, until their sound became a rattle. The physicists watched, fascinated,
as the curve climbed steadily upward. Then the automatic control rod (which had been set for too low a neutron count) slammed
back into the pile with a clang. “I’m hungry,” deadpanned Fermi. “Let’s go to lunch.”
⁸⁰
The other rods were inserted and the pile quieted down. He was drawing out the suspense like an accomplished showman.

At 2
P.M.
everyone gathered again in the squash court. This time a crowd stood on the balcony. Szilard and Compton watched Fermi standing
above what looked like an ominous black beehive. One by one, on Fermi’s orders, the control rods were withdrawn, the counters
clicking faster. The pile was alive with neutrons now. But it was not quite a chain reaction. Fermi ordered the control rod
out another foot. He was enjoying himself tremendously. The pile was nearly critical. “This is going to do it!” Fermi announced.
“Now it will become self-sustaining!”
⁸¹
An eyewitness recalled:

At first you could hear the sound of the neutron counter, clickety-clack, clickety-clack. Then the clicks came more and more
rapidly, and after a while they began to merge into a roar; the counter couldn’t follow anymore. That was the moment to switch
to the chart recorder. But when the switch was made, everyone watched in the sudden silence the mounting deflection of the
recorder’s pen. It was an awesome silence. Everyone realized the significance of that switch; we were in the high intensity
regime and the counters were unable to cope with the situation anymore. Again and again, the scale of the recorder had to
be changed to accommodate the neutron intensity which was increasing more and more rapidly. Suddenly Fermi raised his hand.
“The pile has gone critical,” he announced. No one present had any doubt about it.
⁸²