Bomb (12 page)

Scribbling graphs and formulas on the blackboard as he spoke, Serber began to explain the physics of an atomic bomb. “He wasn't much of a speaker,” the physicist Isidor Rabi recalled, “but for ammunition he had everything Oppenheimer's theoretical group had uncovered during the last year. He knew it all cold and that was all he cared about.”

Serber had the room's attention—until a sharp
crack
interrupted the talk. Startled, everyone looked up. They saw a jagged hole in the thin ceiling above, and, dangling through the hole, the wiggling leg of an electrician. The scientists heard the man call for help. They heard men running on the floor above, then saw the leg slowly slide up through the hole and disappear.

Serber returned to his lecture. Almost every sentence included the word
bomb
, which began to worry Oppenheimer. He leaned to the physicist beside him, John Manley, and whispered something. Manley walked up to Serber and told him to stop saying “bomb”—there were too many workers around.

When Serber resumed his talk, he referred instead to the “gadget.” The name stuck. “Around Los Alamos after that,” explained Serber, “we called the bomb we were building ‘the gadget.'”

*   *   *

I
N FOUR MORE LECTURES
over the next two weeks, Serber described the physics of how the gadget might work. Enrico Fermi's Chicago experiment had proved that it was possible to spark a chain reaction in uranium. Fermi's uranium and graphite pile had released energy, but only a tiny amount, and slowly. The problem facing Oppenheimer's team was to figure out how to create a much faster chain reaction that would release so much energy it would cause a massive explosion—and the whole thing had to be light enough to travel by airplane.

In theory, Serber explained, the design of the bomb could be very simple. They could load two pieces of very pure uranium into a specially adapted artillery gun. Inside the gun barrel, they would fire one piece of uranium at the other. When the two pieces met, they would form a critical mass, the amount of material needed to get a chain reaction going. The reaction would begin—speeding neutrons would hit uranium atoms, which would split, releasing energy and more neutrons. Each fission would release just enough energy to move a grain of sand. But within less than one millionth of a second, so many atoms would fission that the lump of uranium would blow itself apart with the force of millions of pounds of regular explosive.

Serber drew a rough sketch of what became known as the “gun assembly” method. Surrounding the uranium would be a tamper—a shield of very dense metal. The tamper would prevent flying neutrons from escaping, bouncing them instead back into the uranium. This would cause more fission, and a bigger explosion.

Major questions remained, Serber told the team. Exactly how much uranium was needed to form a critical mass? What material would perform best as a tamper? How fast would the lumps of uranium need to be brought together inside the gun? How big an explosion would this type of bomb cause? And, of course, would this design even work?

“We started working immediately,” said Richard Feynman.

*   *   *

O
UTSIDE THE WORKROOMS,
Los Alamos was a disaster.

“The site itself was a mess,” said Robert Serber. “It was a shambles,” agreed Hans Bethe. “It was a construction site. You stumbled over kegs of nails, over posts, over ladders.”

Melting snow sank into the dirt roads, turning them to sticky black mud. And while views of the surrounding mountains and deserts were spectacular, the army built high fences around the entire lab—making the scientists feel like prisoners.

“The first thing I noticed,” remembered Edward Teller, “was that we were all going to be locked up together for better or for worse.”

“I was shocked by the isolation,” Bethe said. “Clearly we were very far from anything, very far from anybody.”

Oppenheimer and his wife moved into one of the five log cabins that had originally been built for school directors, a little group of houses known as “Bathtub Row”—they had the only tubs on the Hill. Younger scientists crowded into bunk beds in an old school building while new dorms were being built. “Bob Christy and his wife had to go to the bathroom through our bedroom,” recalled Feynman. “So that was very uncomfortable.”

As construction continued, Oppenheimer was often seen strolling the streets of his growing town in jeans and a Western shirt, his thumbs tucked into his belt. New scientists were arriving all the time, and when the director saw someone he didn't know, he'd stride up to the newcomer.

“Welcome to Los Alamos,” he'd say, smiling. “And who the devil are you?”

*   *   *

T
O GET TO WORK,
scientists struggled through the mud to the half-finished Tech Area, which housed labs and offices and was surrounded by another fence, nine feet high, with barbed wire strung along the top. Military police guarded the only gate twenty-four hours a day. To gain entrance, scientists had to show their white badges—only the scientists were issued these special photo IDs.

Oppenheimer arrived at the gate of the Tech Area each morning at 7:30, flashed his white badge, and walked to his office. This was a big change from his Berkeley days. A lover of late-night parties, he'd never scheduled classes before 11:00 a.m. But Oppenheimer knew that it wasn't just his reputation and career on the line at Los Alamos—it was the outcome of the biggest war in human history.

And in case the pressure wasn't intense enough, President Roosevelt spelled it out in a personal note. “Whatever the enemy may be planning, American science will be equal to the challenge,” Roosevelt wrote to Oppenheimer. “With this thought in mind, I send this note of confidence and appreciation.”

Oppenheimer thanked Roosevelt for the kind words, adding, “There will be many times in the months ahead when we shall remember them.”

Then came a memo from General Leslie Groves. Given Oppenheimer's vital importance to the country, wrote Groves, “it is requested that:

(a) you refrain from flying in airplanes of any description; the time saved is not worth the risk.

(b) you refrain from driving in an automobile for any appreciable distance (above a few miles) and from being without suitable protection on any lonely road.

(c) in driving about town, a guard of some kind should be used, particularly during hours of darkness.”

These were sensible precautions, but the truth is that Groves had more than safety on his mind. Many of Groves's intelligence officers still didn't trust the Los Alamos director. They believed he was secretly a Communist, and perhaps even in touch with Soviet agents. They wanted him under constant surveillance.

Army Counter-Intelligence Corps (CIC) agents hid microphones in Oppenheimer's office. They listened in on his phone calls and read his mail. Even Oppenheimer's personal driver and bodyguard—the one Groves insisted he have—was actually an undercover agent. Oppenheimer sensed he was being watched, but he never guessed how closely.

On June 12, he traveled to Berkeley to recruit more brains for Los Alamos. CIC agents followed him every step of the way.

LABORATORY NUMBER 2

BY EARLY 1943,
the Soviet army had finally halted the massive German invasion just short of the Soviet cities of Stalingrad, Moscow, and Leningrad. “The greatest military achievement in all history,” praised Douglas MacArthur, a top American general.

But the fighting raged on, with some of the biggest battles in the history of war taking place on the blood-soaked Soviet soil that spring. Joseph Stalin, the Soviet premier, called desperately for the Americans and British to launch an invasion of German-held Western Europe. This would force Hitler to fight on two fronts, taking pressure off the Soviets.

President Franklin Roosevelt and British Prime Minister Winston Churchill told Stalin it was coming. American and British troops were just beginning their attack on Germany's ally, Italy. And American forces were locked in ferocious battles with Japan all over the Pacific. A major invasion of Western Europe was still a year away.

Americans continued shipping weapons to the Soviets, but the atomic bomb remained a secret. In fact, Roosevelt and Churchill signed a special agreement, vowing to keep it that way. It was the job of Army Counter-Intelligence to guard the world's most dangerous secret—not just from the Germans, but from the Soviets as well. So CIC officers were determined to investigate any suspicious behavior.

Especially when it came from the director of Los Alamos.

*   *   *

O
N
J
UNE 14,
CIC agents tailed Oppenheimer onto a train heading from Berkeley to San Francisco. At the San Francisco station, they watched as Oppenheimer was greeted by a tall woman with dark hair. They recognized her as Jean Tatlock, a former girlfriend of Oppenheimer's and a member of the Communist Party.

Oppenheimer and Tatlock walked arm in arm to Tatlock's car, got in, and drove off. The agents followed the car to a Mexican restaurant in San Francisco. Oppenheimer and Tatlock went inside, had dinner and drinks, then drove to her apartment, and entered together. The agents sat in their car, watching the windows. Tatlock's lights went out at 11:30. “Oppenheimer was not observed until 8:30 a.m. next day,” the agents reported, “when he and Jean Tatlock left the building together.”

The agents sent their report to Lt. Colonel Boris Pash, the top army intelligence officer on the West Coast. He'd already suspected Oppenheimer of disloyalty. Now he was seriously alarmed.

Pash reported to General Groves's office in Washington, D.C., suggesting that the “subject still is or may be connected with the Communist Party.” Pash believed that Oppenheimer was either handing secrets directly to the Soviets, “or he may be making that information available to his other contacts”—Jean Tatlock, for instance.

Pash strongly recommended that Oppenheimer “be removed completely from the project and dismissed from employment by the U.S. Government.”

Groves refused. He had no idea what Oppenheimer and Tatlock had been up to in her apartment. He didn't want to know. He trusted Oppenheimer's loyalty. Besides, his number one worry was to build an atomic bomb before Hitler did. For this, he said, “Oppenheimer is irreplaceable.”

“If anything happens to Oppenheimer,” he added, “the project will be set back at least six months.”

Groves's word was final. But if Army Counter-Intelligence couldn't get rid of Oppenheimer, they could certainly let him know how they felt.

“In the future, please avoid seeing your questionable friends,” Colonel Kenneth Nichols told Oppenheimer. “And remember, whenever you leave Los Alamos, we will be tailing you.”

This frightened Oppenheimer. He had no idea how long intelligence agents had been following him, or what they already knew about his private life. Suddenly worried about losing his position at Los Alamos, he decided to tell Colonel Pash about the time, six months earlier, that his friend Haakon Chevalier had approached him about sharing information with the Soviets. Oppenheimer repeated the brief conversation he had had with Chevalier. He assured Pash the subject had not come up again.

Oppenheimer hoped this confession would convince Pash of his loyalty. Instead, Pash was more suspicious than ever.
Had the Chevalier meeting really been that innocent
? Pash wondered.
If so, why did Oppenheimer wait so long to tell us about it
?

Pash dashed off another memo to Groves, this time accusing Oppenheimer of “playing a key part in the attempts of the Soviet Union to secure, by espionage, highly secret information which is vital to the security of the United States.”

Again, Groves defended the man he'd chosen.

*   *   *

A
RMY
C
OUNTER-
I
NTELLIGENCE
and the FBI still believed Oppenheimer was sneaking information to the Soviets. There's no evidence that he was. Soviet memos and cables from the time show that the KGB never gave up hope of cultivating Oppenheimer—but never made any progress, either.

Meanwhile, the Soviet atomic bomb project was moving ahead. In mid 1943, the Soviet government established “Laboratory Number 2,” a secret lab in the pine woods outside Moscow. The job of building the Soviet bomb was put in the hands of a forty-year-old physicist named Igor Kurchatov.

With resources short during wartime, Kurchatov and his team badly needed help from Soviet spies. Intelligence was still coming in from Klaus Fuchs in Britain, and it was good stuff. “The material as a whole,” reported Kurchatov, “shows that it is technically possible to solve the entire uranium problem in a much shorter period than our scientists believed.”

But what Kurchatov really needed was specific information on bomb design, and there was only one place to get it. “It is extremely important,” he said, “to receive detailed technical material on this problem from America.”