Diana Preston - Before the Fallout

“Mr. Baker” was, of course, Niels Bohr. He had been given a pseudonym, just as Oppenheimer was “Mr. Smith,” Lawrence was “Mr. Jones,” and Fermi was “Mr. Farmer.” Bohr was fortunate to be alive. In early 1943 British intelligence had received a warning from Denmark that Bohr was likely to be deported to Germany. A message from James Chadwick inviting Bohr to England was smuggled into Denmark on microdots concealed in two ordinary-looking doorkeys. Chadwick promised “a very warm welcome and an opportunity of service in the common cause.” Bohr, however, was reluctant to leave Denmark, knowing his flight would expose family and colleagues to Nazi reprisals. His reluctant refusal—reduced to a two-by-three-millimeter microdot—was smuggled out of Denmark in the hollow tooth of a resistance worker.

The rapidly worsening position in Denmark altered Bohr’s view. News of the Russians’ victory at Stalingrad at the end of January 1943 had encouraged the Danish resistance to launch a series of sabotage attacks. The Germans responded by shooting hostages, prompting a series of strikes that the Germans again savagely suppressed. On 28 August 1943 the Danish government resigned, and the following day the Germans declared martial law. The British sent a further, urgent message to Bohr, passed to him by word of mouth: “We still are waiting for you.”

A few days later Bohr learned from informants that the Germans planned to deport “undesirable aliens.” Realizing that this meant Jewish refugees in Copenhagen, he warned those of his staff who were at risk, helped them contact the Danish underground, who would assist them to flee to Sweden, and gave them money. He expected at any moment to be arrested himself. In fact, as emerged at the Nuremberg war crimes trials, the Germans had intended to seize him the day they declared martial law. They had, however, changed their mind, fearing that it would attract too much attention. They decided, instead, to arrest Bohr during a general roundup of Denmark’s Jews.

Bohr hurriedly destroyed his papers. He also dissolved in acid the gold Nobel medals that James Franck and Max von Laue had left with him for safekeeping. They lived out the war in an innocent-looking bottle on a cluttered shelf, and the gold was later retrieved and recast. On 29 September Mar-grethe Bohr’s brother-in-law brought the news Bohr had been expecting. According to a contact in the German diplomatic corps, Berlin had ordered the deportation of Niels and his brother Harald to Germany. Bohr knew that he and Margrethe had to leave at once. Friends arranged for a boat to take them to Sweden and promised to send their sons after them.

Copenhagen was under strict nighttime curfew. Anyone out on the streets after the deadline was shot on sight. The Bohrs therefore had to try to reach a beach undetected while it was still daylight. In the late afternoon they walked down a still-crowded street, carrying only a small bag. A scientist friend, standing on the corner, gave Bohr a surreptitious nod—the signal that everything was in place for the escape. The Bohrs made their way to fields beyond the city and hid in a shack until dark. They were supposed to make their escape at 9 p.m. However, as Margrethe Bohr recalled, when the time came the Nazis “had come out so that we had to wait until late in the night.” When at last the coast was literally clear, the Bohrs hurried down to the beach. It was, Margrethe remembered, “very dramatic”—“you had to throw yourself down to the ground not to be seen.” They clambered gratefully aboard a small motorboat waiting to take them out to the fishing boat that would carry them to Sweden.

Safely arrived near Malmo, Margrethe waited for their sons while Bohr hurried to Stockholm. His mission was to plead for Denmark’s Jews, who, he knew, were about to be rounded up and shipped to concentration camps. The neutral Swedish government, which had tried unsuccessfully to intercede on behalf of Norway’s Jews, agreed to help and broadcast a formal announcement offering sanctuary to Danish Jews. This offer prompted one of the most honorable and courageous acts of the war. The Danish underground assembled a fleet of small boats and ferried their Jewish countrymen to safety in Sweden. The dangerous shuttle operation saved nearly 6,000. The Nazis were able to deport only 472 Jews, many elderly, helpless, and living in old people’s homes. One of Niels Bohr’s aunts was among them. She did not survive.

The rest of Bohr’s family reached Sweden safely. Margrethe and their younger sons would remain there for the rest of the war, but within weeks Bohr received a telegram from Lord Cherwell, inviting him to England. This time he accepted. On 6 October 1943 a British Mosquito fighter bomber—painted in civilian livery, unarmed, and flown by two civilians to avoid violating Swedish neutrality—landed in Stockholm. The only available space for the large-framed Bohr was in the empty bomb bay, which had been specially padded to take a passenger. He was equipped with flying suit, parachute, and a set of distress flares and told that if the Luftwaffe attacked the plane, the pilot would open the bomb-bay doors, jettisoning Bohr, who was to parachute into the sea and send up the flares. He was also given a helmet fitted with headphones, which was the only means the crew had of communicating with him.

To avoid attack, particularly from Luftwaffe bases in Norway, the Mosquito at first flew at very high altitude. The pilot instructed Bohr to turn on his oxygen supply, but unfortunately Bohr’s helmet was too small for his gigantic cranium. The headphones did not cover his ears, and he never heard the order. He lost consciousness; but as the Mosquito descended he began to revive, and by the time it landed in Scotland he was conscious once more.

Bohr was flown on to London, where James Chadwick was waiting to greet him. Since 1940 Bohr had been cut off from information about British and American progress on atomic research. He was amazed by what he soon learned-—especially that Enrico Fermi had achieved a self-sustaining chain reaction. Bohr was assigned an office near the London headquarters of the Directorate of Tube Alloys, where he was joined by his son, Aage, as his assistant. Bohr spent the next few months visiting laboratories across the country and bringing himself up to speed. The reality of a nuclear bomb disturbed as well as fascinated him, and he already foresaw that it could, in the future, prompt an arms race.

The British tried to persuade Bohr to go to the United States as part of their team under the Quebec Agreement. Bohr, who had close personal ties with America as well as Britain, was reluctant to be affiliated with any particular camp. To meet his concerns and to allow him the requisite degree of independence, he was appointed as “Consultant to the British Directorate of Tube Alloys.” His brief was to review the work under way in the United States and decide how he could best assist the common goal.

Niels and Aage Bohr sailed for the New World under their assumed names of Nicholas and James Baker. However, the FBI agents who met them as they disembarked were horrified to see “NIELS BOHR” written in large black letters on “Nicholas Baker’s” suitcase. General Groves accompanied them on the long train journey from Chicago to Lamy, New Mexico—the nearest station to Los Alamos. To keep the Danes’ presence on the train secret, Groves ordered their meals to be served in their compartment. He was chagrined to discover that on both mornings of the long journey the Bohrs breakfasted in the dining car. Groves found the journey stressful in other ways. During their hours of confinement he found Bohr hard to understand. The morning after they reached Los Alamos, Oppenheimer noticed that the general seemed below par and asked him what the matter was. Groves replied, “I’ve been listening to Bohr.”