by Craig Nelson
Niels Bohr was outraged after reading this in Jungk’s book, for he remembered that in 1941 Heisenberg was elated to be making nuclear weapons for Hitler. Bohr’s wife, Margrethe, remembered the meeting in detail: “Heisenberg stated that he was working on the release of atomic energy and expressed his conviction that the war, if it did not end with a German victory, would be decided by such means. Heisenberg said explicitly that he did not wish to enter into technical details but that Bohr should understand that he knew what he was talking about as he had spent two years working exclusively on this question. Bohr restrained himself from any comment but understood that this was important information which he was obliged to try to bring to the attention of the English. . . . Heisenberg and Weizsäcker sought to explain that the attitude of the Danish people towards Germany, and that of the Danish physicists in particular, was unreasonable and indefensible since a German victory was already guaranteed and that any resistance against cooperation could only bring disaster to Denmark. . . . Weizsäcker further stated how fortunate it was that Heisenberg’s work would mean so much for the war since it would mean that, after the expected great victory, the Nazis would adopt a more understanding attitude towards German scientific efforts.” Other Danish physicists at the meeting said that Heisenberg “stressed how important it was that Germany should win the war. . . . The occupation of Denmark, Norway, Belgium and Holland was a sad thing but as regards the countries in Eastern Europe it was a good development because these countries were not able to govern themselves.”
After reading Jungk, Bohr wrote several letters to Heisenberg about this meeting but had never mailed them, and after his death Bohr’s private papers, including these letters, were to remain sealed until the year 2012. But when Michael Frayn’s 1998 play Copenhagen turned the incident into a global conversation about the morality of science in a time of war, the Niels Bohr Archive decided to release the correspondence to protect Bohr’s reputation . . . and seal Heisenberg’s:
Dear Heisenberg,
I have seen a book by Robert Jungk, recently published in Danish, and I think that I owe it to you to tell you that I am greatly amazed to see how much your memory has deceived you in your letter to the author of the book, excerpts of which are printed in the Danish edition.
Personally, I remember every word of our conversations, which took place on a background of extreme sorrow and tension for us here in Denmark. In particular, it made a strong impression both on Margrethe and me, and on everyone at the Institute that the two of you spoke to, that you and Weizsäcker expressed your definite conviction that Germany would win and that it was therefore quite foolish for us to maintain the hope of a different outcome of the war and to be reticent as regards all German offers of cooperation. I also remember quite clearly our conversation in my room at the Institute, where in vague terms you spoke in a manner that could only give me the firm impression that, under your leadership, everything was being done in Germany to develop atomic weapons and that you said that there was no need to talk about details since you were completely familiar with them and had spent the past two years working more or less exclusively on such preparations. I listened to this without speaking since [a] great matter for mankind was at issue in which, despite our personal friendship, we had to be regarded as representatives of two sides engaged in mortal combat. That my silence and gravity, as you write in the letter, could be taken as an expression of shock at your reports that it was possible to make an atomic bomb is a quite peculiar misunderstanding, which must be due to the great tension in your own mind. From the day three years earlier when I realized that slow neutrons could only cause fission in Uranium 235 and not 238, it was of course obvious to me that a bomb with certain effect could be produced by separating the uraniums. In June 1939 I had even given a public lecture in Birmingham about uranium fission, where I talked about the effects of such a bomb but of course added that the technical preparations would be so large that one did not know how soon they could be overcome. If anything in my behavior could be interpreted as shock, it did not derive from such reports but rather from the news, as I had to understand it, that Germany was participating vigorously in a race to be the first with atomic weapons.
In another undated letter never sent to Heisenberg, Bohr wrote: “I remember quite clearly the impression it made on me when, at the beginning of the conversation, you told me without preparation that you were certain that the war, if it lasted long enough, would be decided with atomic weapons. I did not respond to this at all, but as you perhaps regarded this as an expression of doubt, you related how in the preceding years you had devoted yourself almost exclusively to the question and were quite certain that it could be done, but you gave no hint about efforts on the part of German scientists to prevent such a development.”
When Bethe returned to Germany after the war in 1948, Heisenberg told him he’d been developing an atomic bomb for the Nazis and came up with another series of reasons for his quisling behavior. Hans Bethe: “He said that his main aim had been to save the lives of German physicists. . . . The second reason he gave was that he believed making an atomic bomb was far beyond the means of any country during the war. . . . His third reason was that in 1942 he had come to the conclusion that the Germans should win the war. This struck me as a very naive statement. He said he knew that the Germans had committed terrible atrocities against the populations on the Eastern Front—in Poland and Russia—and to some extent in the West as well. He concluded that the Allies would never forgive this and would destroy Germany as a nation—that they would treat Germany about the way that Romans had treated Carthage. This, he said to himself, should not happen; therefore, Germany should win the war, and then the good Germans would take care of the Nazis.”
Things were in fact much less fruitful in Berlin than Heisenberg had implied in Copenhagen. On December 16, 1941, Bothe, Hahn, Harteck, and Heisenberg reported a series of uranium research disappointments, and the army ordnance department responded by withdrawing entirely from the nuclear program, as well as from KWI itself, turning everything back over to the (far less moneyed and influential) Reich Research Council. On February 26, 1942, the Uranverein tried to reverse its fall from grace by inviting every significant military and government official to a crucial technical progress announcement on nuclear weapons in Berlin. But along with the invitation came the news that everyone would be treated to an experimental flash-frozen lunch deep-fried in synthetic lard. Not a single influential Nazi attended, and the Uranverein fell further behind in funding and influence.
Then, at the end of April 1942, Albert Speer, Hitler’s second-in-command, was told by General Friedrich Fromm, chief of the army’s training and reservists, that the only way the Germans could win would be through a new weapon some scientists were working on that could “annihilate whole cities.” Speer asked Hitler to appoint Göring as head of the Reich Research Council to elevate the program (which Hitler did) and called for a meeting with the Uranverein on June 4, joined by the heads of ordnance, navy armaments, and the air force. Speer asked the physicists what kind of funding they needed; Weizsäcker responded with 40,000 reichsmarks, a ridiculously low number. Speer asked again for a figure, and they responded with 350,000 marks ($80,000). Speer thought this, too, was absurd (almost this exact same meeting had played out in 1941 in Schenectady, when American physicists had no idea how to estimate the cost of developing nuclear arms and responded to the US War Department’s questions with comically flailing sums). On June 23, Speer told Hitler that nuclear science would reap benefits in the distant future, but no superbomb could be produced in time to affect the war. The German military once again abandoned nuclear research.
The same day that Speer and Hitler gave up on physics, Heisenberg almost died. His Leipzig experimental reactor developed a leak, and water reached the uranium metal, creating hydrogen bubbles. Robert Döpel had the pile pulled out of its water tank, and a technician opened one of the sphere’s inlet valves. Air immediately flowed in,
setting the uranium powder on fire, which sprayed out. Döpel and the technician were able to put out the fire and return the sphere to its tank, but a little later, he and Heisenberg were in the lab when they noticed the sphere was beginning to swell. They ran outside as fast as they could, and the reactor exploded, destroying the uranium, the lab, and the heavy water. When the two scientists had to explain to the city fire department what they were doing, the firemen sarcastically congratulated them on their remarkable achievement in science. A rumor, however, spread across Germany that scientists had been killed in a uranium bomb explosion, and it reached Leo Szilard. To those inside the Manhattan Project, this could only mean that the Germans had already initiated a sustained chain reaction, meaning they were at least a year ahead of the Allies in developing nuclear arms.
Believing the Nazis were equal or better when it came to research and development, in the heat of the war and the New Mexican desert of Los Alamos, the scientists and engineers rushed pell-mell forward to beat Hitler at the mastery of nuclear arms. Isidor Rabi: “The big problem was: Where was the enemy in the field of work? We finally arrived at the conclusion that they could be exactly up to us, or perhaps further. We felt very solemn. One didn’t know what the enemy had. One didn’t want to lose a single day, a single week. And certainly, a month would be a calamity.” Germany’s visible military losses during this period did not encourage the expatriates in New Mexico; they assumed the Reich’s leaders would become desperate and turn to desperate solutions.
A number became convinced that the Nazis had a two-year lead on the Allies. Bethe and Teller wrote Oppenheimer on August 21, 1943, of their worries that the American effort wasn’t moving fast enough: “Recent reports both through the newspapers and through secret service, have given indications that the Germans may be in possession of a powerful new weapon which is expected to be ready between November and January. There seems to be a considerable probability that this new weapon is tube alloy [i.e., uranium]. It is not necessary to describe the probable consequences which would result if this proves to be the case. It is possible that the Germans will have, by the end of this year, enough material accumulated to make a large number of gadgets which they will release at the same time on England, Russia and this country. In this case there would be little hope for any counter-action. However, it is also possible that they will have a production, let us say, of two gadgets a month. This would place particularly Britain in an extremely serious position but there would be hope for counter-action from our side before the war is lost, provided our own tube alloy program is drastically accelerated in the next few weeks.”
Others at the mesa thought Allied efforts were lagging because of the slow-moving corporations managing production and suggested that Fermi and Urey lead a crash course in R&D on heavy-water piles that could be overseen directly by the physicists in New Mexico. Then in the autumn of 1944, the émigrés were terrified to learn that the Nazis had taken over the French company Terres-Rares and had shipped a notable amount of thorium back to Germany. Could they have developed a highly advanced thorium reactor? As it turned out, the German chemical company Auer, sensing that the war was coming to a close, had forcibly cornered the thorium market, hoping to cash in on the craze for radioactive cosmetics, especially its thorium toothpaste, which promised to give you “sparkling, brilliant teeth—radioactive brilliance!”
But there were few reasons to laugh at the time. Ed Teller: “The thought of how far the Germans might have come in the years since the discovery of fission was enough to give us all nightmares.”
Philip Morrison remembered believing that “the only way we could lose the war was if we failed in our jobs.”
As the Third Reich sputtered to its gruesome final months, a combination of gossip, competing evidence, and the urgent need to get security officer Boris Pash to stop bothering him about Robert Oppenheimer’s youth of Communist flirtation inspired Leslie Groves to create Project Alsos. Greek for “grove” and a play on the general’s name, Alsos was a scientific intelligence mission that followed victorious Allied troops across Europe to assess the status of the German nuclear program, as well as prevent the Russians from amassing nuclear materials and scientific manpower. Simultaneously with Alsos, Groves set up AZUSA with the OSS, sending in onetime Boston Red Sox catcher, attorney, and linguist Moe Berg to interview Amaldi, Wick, and other scientists whose names were provided by Fermi. Groves ordered Colonel Carl Eifler to kidnap Heisenberg and bring him to America, depriving the Nazis of their chief nuclear scientist. If the kidnapping was not successful, Eifler was told to “deny the enemy his brain.” But Eifler’s plan was so convoluted, with so many things that could go wrong, that it was eventually canceled. Instead, Moe Berg was sent to listen to a December 1944 lecture given by Heisenberg in Zurich. If Berg thought the Germans were close to having nuclear weapons, he was to kill Heisenberg in what would have become a suicide mission. Berg wasn’t schooled enough in physics to make a decision on German weaponry based on the lecture, but he was then invited to join a group for dinner, a group that included Heisenberg. When the physicist admitted that the Germans were lost, Berg understood that there could be no Hitler-triggered nuclear holocaust, and Heisenberg’s life was saved.
Groves now asked for known scientific institutions to be included in Allied bombing runs, and on February 15, 1944, the Kaiser Wilhelm Institute for Chemistry, the Dahlem home to Meitner, Hahn, and Strassmann, was fully destroyed. In December of 1943, Heisenberg’s Leipzig house had been decimated in an aerial assault; another air raid completely destroyed Max Planck’s house. Then Planck’s first son, Erwin, was arrested for taking part in von Stauffenberg’s failed assassination of Hitler. He was tortured by the Gestapo and hanged to death.
The Uranverein moved, with KWI, away from heavily targeted Berlin to a small town in the Black Forest. When Strasbourg was liberated in November 1944, Alsos leader Samuel Goudsmit uncovered a letter dated three months before, from one of the Uranverein to Heisenberg, discussing piles, but not bombs, and the intelligence team knew how far behind the Nazi scientific effort had fallen. Even so, it was believed in America’s interest to ensure that none of the German scientists or their documents and equipment fell into Russian hands. When Alsos discovered eleven hundred tons of Belgian Congo uranium ore in a factory that would fall into the postwar Soviet zone, it was packed up and shipped to the United States. When Groves’s overseas team then determined that a metal-refining plant fifteen miles north of Berlin, also to be included in the Soviet sector, was the source of uranium processing for a reactor, “since there was not even the remotest possibility that Alsos could seize the works, I recommended to General Marshall that the plant be destroyed by air attack,” Groves recalled. It was destroyed, keeping at least that fuel away from the Soviets as well.
Just as the American army with Paperclip swept in to mop up Wernher von Braun and his team of scientists and engineers who developed the V-2 rocket—an effort strategic for both NASA and the Cold War’s missile race—so Alsos, headed by Pash and American physicist Sam Goudsmit, dismantled Heisenberg’s toylike reactor and captured Bagge, von Laue (who had nothing to do with the program), Hahn, Heisenberg, and six other scientists from the Nazi bomb group. Just as with von Braun and his team, the Uranverein had fled west in the war’s last months to avoid being taken prisoner by the Russians and believed their work would save them. A few tried in the last moments to get a reactor burning, but it was too late. When Werner Heisenberg was caught, he thought the British and the Americans would be fascinated by his research, having no idea how long ago he had been eclipsed by Los Alamos. After finishing his mission, meanwhile, Sam Goudsmit would come to believe that America had spent more on Alsos than the Nazis had spent on the whole of Germany’s wartime nuclear research.
Under Allied guard, the Uranverein were taken to Farm Hall in England, the SOE’s country house. Unlike America with its habeas corpus, interrogation under British law allows detaining anyone for six months “at
His Majesty’s pleasure,” and Farm Hall was bugged inch by inch. Not, however, until February 24, 1992, did the British release the transcripts, and before that time the Germans were able to rewrite much of this history.
As captured by SOE’s microphones, the Nazi scientists were initially fearful that they would be turned over to the Russians. They frequently discussed how their work, at the forefront of science before Hitler, was probably being deeply studied by the Allies at that moment, with scientists across the United States re-creating their signal experiments. Then they were told that America had spent 500 million pounds and employed 125,000 people to develop an atomic bomb with the power of twenty thousand tons of TNT, which they dropped on Japan. Twice. The Germans fell into a profound shock. Werner Heisenberg thought that it was so impossible, it had to be a lie. Otto Hahn thought his role in discovering fission left him responsible and considered the only honorable action would be to commit suicide.
Then they started rationalizing their failures as both Germans and as scientists. Heisenberg: “We wouldn’t have had the moral courage to recommend to the government in the spring of 1942 that they should employ 120,000 men just for building the thing up.” Weizsäcker: “I think it was dreadful of the Americans to have done it. . . . I believe the reason we didn’t do it was because all the physicists didn’t want to do it, on principle. If we had all wanted Germany to win the war, we would have succeeded. . . . History will record that the Americans and the English made a bomb, and that at the same time the Germans, under the Hitler regime, produced a workable [reactor].”