The First War of Physics (44 page)

Heisenberg himself was nowhere to be found, but his disappearance was not a mystery. The German physicists made no secret of the fact that he had left Hechingen a few days before, in an attempt to get back to his family in Urfeld, 120 miles away. His journey, largely by bicycle through the detritus of war, was nerve-wracking and exhausting. Aside from the constant threat of Allied fighters roaming the skies searching for targets, there was also the risk of instant, roadside justice meted out by SS units carrying out Hitler’s order to fight to the end. The SS officers would simply pronounce sentence and shoot or hang ‘deserters’ on the spot.

It took Heisenberg three days to get to Urfeld, arriving on 23 April. ‘And finally, suddenly and unexpectedly, I saw him coming up the mountain, dirty, dead tired and happy’, his wife Elisabeth wrote years later. They celebrated the announcement of Hitler’s suicide with their last bottle of wine, and with tears of relief. On 3 May he was visiting his mother, who had also moved to Urfeld and was staying at an apartment in the village, when he received a call from Elisabeth. He returned home promptly to find Pash and a small detachment of men waiting to take him into custody. For Heisenberg his capture was a mixed blessing: ‘I felt like an utterly exhausted swimmer setting foot on firm land.’

The Alsos mission caught up with Gerlach and Diebner in Munich on 1 May, and with Harteck in Hamburg.

A photograph that had been recovered from Heisenberg’s office in Hechingen showed Heisenberg and Goudsmit together, taken at the dockside in Ann Arbor during their last meeting in the summer of 1939. At this meeting, Goudsmit had challenged Heisenberg about his decision to stay in Germany and had urged him to come to America. Meeting again in Heidelberg under rather different circumstances, Goudsmit now repeated the suggestion, but Heisenberg told him: ‘No, I don’t want to leave. Germany needs me.’ When Heisenberg asked if there was a similar atomic
programme in America, Goudsmit lied and said no. Heisenberg offered help: ‘If American colleagues wish to learn about the uranium problem, I shall be glad to show them the results of our researches.’

Goudsmit found this all rather ‘sad and ironic’. The Tube Alloys and Manhattan Project physicists had always thought themselves to be competing in a race. Yet the German atomic programme hadn’t even succeeded in building a working reactor. Heisenberg had lost the race long ago. But he still did not know this yet.

In the ruins of Berlin

Berlin was encircled by the Soviet First Belorussian Front and First Ukrainian Front, and on 20 April – Hitler’s birthday – Soviet artillery began pounding the city. On 29 April the Soviet Third Shock Army crossed the Moltke Bridge, a short distance from the Königsplatz and the Reichstag. Hitler signed his last will and testament and married Eva Braun. Both committed suicide the next day.

Zavenyagin headed the first of the Soviet search missions to Berlin, arriving on 3 May and occupying a building in Berlin-Friedrichschagen. The search teams variously included Artsimovich, Kikoin, Flerov and Khariton, the latter dressed in the uniform of an NKVD lieutenant-colonel. Kurchatov did not join, perhaps concerned that the NKVD might in future lean towards German, rather than Soviet, science to drive the Soviet atomic programme.

On 4 May the search team visited the Kaiser Wilhelm Institute for Physics in Dahlem. The equipment had long since been moved to Hechingen, but the search team discovered detailed documentation giving a complete description of the German atomic programme. The Soviet physicists were not greatly impressed. Some of Heisenberg’s calculations for the critical size of a nuclear reactor had already been surpassed by Soviet scientists. It was obvious from these documents that the German programme had not advanced very far.

German forces surrendered unconditionally on 7 May. Three days later a Soviet search team headed for Manfred von Ardenne’s laboratory in
Berlin-Lichterfelde. The team found Ardenne waiting, and was this time impressed with what had been achieved at his private laboratory. Along with a prototype electron microscope, the search team found a prototype calutron. Ardenne and Zavenyagin discussed plans for the future, and on 21 May Ardenne flew to Moscow, ostensibly to sign an agreement on the creation of a new physical-technical institute in the Soviet Union.

Ardenne probably figured that he would not be returning to Germany any time soon, when on his arrival in Moscow an interpreter asked: ‘Haven’t you brought your children with you?’ Within minutes of his departing Berlin for the airport, about 100 Soviet soldiers had suddenly appeared and started packing everything that could be moved. A few weeks later, the rest of Ardenne’s laboratory staff arrived in Moscow by train.

Anticipating that the Soviets would capture the Auer uranium production facilities at Oranienburg, Groves had sought to ensure that all they would find was rubble. The Auer plant had been heavily bombed by B17s of the American Eighth Air Force on 15 March. Auer’s chief scientist, Nikolaus Riehl, had moved with some of his staff to a small village west of Berlin in the hope that they would meet British or American forces before the invading Soviet forces arrived. However, he was tracked down by Artsimovich and Flerov, who suggested that he join them for a few days of discussion. That few days was to become ten years.

Riehl had been born in St Petersburg, the son of a Siemens Company engineer, and spoke fluent Russian. A highly competent chemist and mineralogist, he was not allowed to return home. Instead he accompanied the Soviets to what remained of the Auer production facilities, where ‘demounting and loading of everything that was not nailed down or riveted proceeded at full speed’. On 9 June, Riehl departed for Moscow with his family and some of his staff.

Khariton and Kikoin now began a systematic search for uranium. They left Oranienburg just before 100 tons of fairly pure uranium oxide was discovered in the rubble. And a chance encounter, some detective work and interrogations by agents of Soviet army counter-intelligence – Smersh – led them to a leather-tanning plant in Neustadt am Glewe, where more than 100 tons of uranium had been hidden. With the uranium from
Oranienburg, the Soviet mission was able to send back about 300 tons of uranium oxide and other compounds.

This would be enough to support development of the Soviet Union’s first nuclear reactor.

¹
There is tantalising evidence that Diebner’s last Gottow experiment, G-1V, may have actually gone critical for a short time and ended in an accident. There is also evidence that Diebner’s group may have been working on crude atomic weapons, using enriched uranium and lithium deuteride, in an experimental project known to Gerlach but kept secret from Heisenberg, Weizsäcker, and other Uranverein physicists. See Karlsch and Walker, p. 18.

²
As there is no single word in Russian meaning ‘implosion’, Kurchatov used the cumbersome term ‘explosion towards the inside’. It seems likely that this report would also have been partly based on espionage materials derived from Greenglass.

Chapter 15

TRINITY

April–July 1945

G
roves had taken a dislike to Leo Szilard the very first time they had met in October 1942. Ever since then, Szilard had lodged like an increasingly painful thorn in Groves’ backside. Growing ever more annoyed at Szilard’s erratic behaviour, his outspoken criticism of the Manhattan Project’s administration, unauthorised travels and intransigence over his chain-reaction patent claims, Groves had the FBI put him under close surveillance. His contract with the Met Lab had expired at the end of 1942 and was not immediately renewed. He had been obliged to sign over his patents as a condition of his reinstatement.

He rejoined just as the work programme at the Met Lab was winding down, with many physicists heading for Hanford or Los Alamos. The mood at the Met Lab became somewhat restless and depressed. With some time on his hands, he turned his attention to post-war atomic politics.

The problem that he and other like-minded Manhattan Project physicists now confronted was simply stated. The reason for the very existence of the project had been fear of German atomic weapons. Yet, by early 1945, the defeat of Germany seemed certain and fear of a Nazi super-weapon groundless. Rotblat had come to similar conclusions, and had taken the
unilateral decision to leave the project and Los Alamos in December 1944.
¹

This restlessness was not confined to the Met Lab. As work on the Hill accelerated, so too did the intensity of the discussion among many scientists, their sense of moral responsibility growing along with their concern for the likely impact of the ‘gadget’ on future civilisation. Oppenheimer attended many of the discussion meetings, gently but persuasively defusing the situation. If atomic weapons were to foreshadow the end of all conventional war, as Bohr had argued, then Oppenheimer believed the world needed first to see the effects of these new weapons if they were to be properly respected.

To Szilard and many other scientists, it was equally certain that the shock of the first use of such weapons by America would spark an arms race with the Soviet Union. A system of international controls was needed if such a race was to be avoided. In March 1945 he decided to write once more to Roosevelt, and again enlisted Einstein’s support. Unable to share the full details of his memorandum with Einstein, who had never become involved in the Manhattan Project, he asked only that Einstein write him a letter of introduction. Szilard also thought to write to Eleanor Roosevelt, and was delighted to receive an invitation to meet her in Manhattan on 8 May.

The meeting never happened. Roosevelt’s death on 12 April forced Szilard to start again.

Szilard now had to find a channel to Truman. He enlisted the support of a young Met Lab mathematician, Albert Cahn. Cahn hailed from Kansas City, which sat at the heart of Truman’s political base. Born in Missouri, Truman had served as a judge in the Jackson County Court before defeating the Republican incumbent for Missouri, Roscoe C. Patterson, in the 1934 Senate elections. Through Cahn’s contacts, Szilard was able to secure an appointment with Truman at the White House on 25 May.

But Szilard did not get to meet the new president. On the day they were to meet, Truman’s appointments secretary instead pointed Szilard in the direction of James Byrnes, in Spartanburg, South Carolina. Somewhat puzzled, Szilard agreed and made the necessary travel arrangements.

At the time of Szilard’s visit, Byrnes was retired and did not appear to have any role in the new administration. A close confidant of Roosevelt, he had headed the government’s Economic Stabilisation Office and War Mobilisation Board, and had served informally as a kind of’assistant’ president, running the country while Roosevelt ran the war. He had been the favourite for selection as Roosevelt’s running mate for the US presidential election in 1944 in place of Henry Wallace but, much to his disappointment, had lost out to Truman. At Roosevelt’s request, Byrnes had attended the Yalta conference, where he had listened intently and taken copious notes in shorthand.

But Byrnes was not retired. Although the Yalta conference was the limit of his experience of foreign affairs, within days of assuming the presidency, Truman had decided that he should be his new Secretary of State.

The meeting between the erratic physicist and the astute politician from South Carolina went predictably. Szilard made an unfavourable impression on Byrnes, and Byrnes’ seeming inability to grasp the significance of atomic energy left Szilard fearful that a US–Soviet arms race was inevitable. Byrnes suggested that the Soviets might be suitably impressed and therefore more ‘manageable’ if they were shown an example of American military supremacy. ‘I was rarely as depressed as when we left Byrnes’ house and walked to the station’, Szilard wrote.

Targets

As Szilard walked disconsolately back to the station, Groves’ Target Committee was meeting for the last time at the Pentagon. The committee had been tasked with finalising the precise details of the first use of atomic weapons against Japan. Oppenheimer served as an adviser. It had previously identified four potential targets for further study – Kyoto, Hiroshima, Yokohama and Kokura Arsenal – and it was now agreed that
three targets would be reserved: Kyoto, Hiroshima and Niigata. The committee had agreed the height at which the bomb, in this first instance a uranium bomb using the Little Boy design, should be detonated. It had examined the bomb’s likely radiological effects.