The Age of Radiance (33 page)

By May of 1941, the British came to understand why the Nazis were so keenly interested in Norwegian heavy water. The construction superintendent of the dam that powered Vemork, Einar Skinnarland, took a two-week vacation in England, during which he was trained by the Special Operations Executive to be a key member of a commando team, the Norwegian Independent Company. On October 13, 1942, Combined Operations put into effect Operation Freshman. Advance ground party Grouse, nine natives of the region experienced in the local wilderness, were trained by the SOE in pistols, knives, poisons, explosives, hand-to-hand combat, breaking locks, and cracking safes. Led by the twenty-four-year-old Jens Pousson, Grouse would find a landing spot to welcome commandos floating in on gliders, and the combined team would disable the heavy-water plant and then hike 250 miles to the Swedish border. On October 18, Grouse was parachuted in, but the drop turned out to be thirty miles from where they were supposed to be. Terrible weather meant it took them fifteen days to reach their base near the dam. At the same time, Norsk Hydro’s chief of hydrogen research, Jomar Brun, was running a campaign of sabotage within his own plant, putting castor oil in the electrolyte, producing a foam that would stop the process for hours and sometimes days. He didn’t know that others were themselves adding cod-liver oil to achieve the same purpose. Of the five tons of heavy water that Heisenberg wanted by June 1942, Norway delivered one.

On November 11, Grouse informed SOE that they’d found a landing site, and on November 19, two British Halifax bombers towing Horsa Mk.I gliders each carrying seventeen men flew into Norway. These fragile plywood gliders landed in a “controlled crash.” The first Halifax released too soon, and her glider crashed into a mountain, killing seven. The second glider’s towline broke, and it crashed, killing eight. All of the survivors were captured by the Nazis, interrogated, and executed by firing squad. On one officer’s body, the Germans found a map of the Vemork plant. They stationed nine hundred troops in the vicinity, and now the Grouse team was cut off from rescue.

A six-man reinforcement, Operation Gunnerside, parachuted in on February 16, 1943. The Nazis had heavily reinforced the plant, but not its
rail-line depot. From that direction, leader Joachim Ronnenberg snuck into the building, set up demolition charges, and blew up the tanks. Evading the Germans, they raced to an icy plateau and skied to the Swedish border. By August, the Germans had repaired the damages and had the plant running again.

On November 16, 1943, under orders from Leslie Groves, three hundred B-17 Flying Fortresses and B-24 Liberators from the Eighth Air Force took off from East Anglia to drop 700 thousand-pound and 295 five-hundred-pound bombs on Vemork, to end its production of heavy water once and for all. But only two bombs hit the plant directly, and neither took out the electrolysis cells that were the real target, while twenty-two civilians died. SOE agent Knut Haukelid learned that the Nazis were planning to move the whole of the plant and its heavy water to Germany on February 20, 1944, the cargo being railed and ferried through Denmark to Berlin. The SOE arranged an operation to sink the cargo’s Norwegian ferry in the middle of a fjord, ensuring the Nazis could never resurrect their cargo. On February 18, Haukelid snuck onto the ferry and improvised a bomb with two alarm clocks. It worked, and Hitler’s entire stock of heavy water was finally destroyed.

But before this difficult victory, there was the meeting that had so terrified Niels Bohr. On September 15, 1941, accompanied by fellow Uranverein member Carl Friedrich Freiherr von Weizsäcker, Werner Heisenberg took the train from Berlin to Copenhagen to visit his great mentor. After the war, a controversy arose over who said what in Denmark that autumn, a controversy that turned out to be one of many German attempts to rewrite history.

The rewrite began with letters Heisenberg sent to Robert Jungk after reading Jungk’s 1956 history of nuclear science,
Brighter than a Thousand Suns
. In these letters, Heisenberg claimed that he had gone to Copenhagen in 1941 to discuss with Bohr his moral objections about scientists working on nuclear weapons, but that he had failed to say this clearly before the conversation came to a sudden stop. Jungk published portions of the letters in the Danish edition of the book, conveying that Heisenberg suggested he had sabotaged the German bomb project on moral grounds:

With the beginning of the war there arose of course for every German physicist the dreadful dilemma that each of his actions meant either a victory for Hitler or a defeat of Germany, and of course both alternatives presented themselves to us as appalling. . . .

My visit to Copenhagen took place in the fall of 1941; I seem to
remember that it was about the end of October. At that time, as a result of our experiments with uranium and heavy water, we in our “Uranium Club” had come to the following conclusion: It will definitely be possible to build a reactor from uranium and heavy water which produces energy [but] the production of nuclear explosives from reactors obviously could only be achieved by running huge reactors for years on end. . . . This situation seemed to us to be an especially favorable precondition as it enabled the physicists to influence further developments. For, had the production of atomic bombs been impossible, the problem would not have arisen at all; but had it been easy, then the physicists definitely could not have prevented their production. The actual givens of the situation, however, gave the physicists at that moment in time a decisive amount of influence over the subsequent events, since they had good arguments for their administrations—atomic bombs probably would not come into play in the course of the war, or else that using every conceivable effort it might yet be possible to bring them into play. That both kinds of arguments were factually fully justified was shown by the subsequent development; for, in fact, the Americans could not employ the atomic bomb against Germany. . . .

Because I knew that Bohr was under surveillance by German political operatives and that statements Bohr made about me would most likely be reported back to Germany, I tried to keep the conversation at a level of allusions that would not immediately endanger my life. The conversation probably started by me asking somewhat casually whether it were justifiable that physicists were devoting themselves to the Uranium problem right now during times of war, when one had to at least consider the possibility that progress in this field might lead to very grave consequences for war technology. Bohr immediately grasped the meaning of this question as I gathered from his somewhat startled reaction. He answered, as far as I can remember, with a counter-question: “Do you really believe one can utilize Uranium fission for the construction of weapons?” I may have replied, “I know that this is possible in principle, but a terrific technical effort might be necessary, which one can hope, will not be realized anymore in this war.” Bohr was apparently so shocked by this answer that he assumed I was trying to tell him Germany had made great progress towards manufacturing atomic weapons.

In my subsequent attempt to correct this false impression I must not have wholly succeeded in winning Bohr’s trust, especially because I only dared to speak in very cautious allusions (which definitely was a mistake on my part) out of fear that later on a particular choice of words could be held against me. I then asked Bohr once more whether, in view of the obvious moral concerns, it might be possible to get all physicists to agree not to attempt work on atomic bombs, since they could only be produced with a huge technical effort anyhow. But Bohr thought it would be hopeless to exert influence on the actions in the individual countries, and that it was, so to speak, the natural course in this world that the physicists were working in their countries on the production of weapons. . . . Since 1933 Germany had lost a number of excellent German physicists through emigration, the laboratories at universities were ancient and poor due to neglect by the government, the gifted young people often were pushed into other professions. In the United States, however, many university institutes since 1932 had been given completely new and modern equipment, and been switched over to nuclear physics. Larger and smaller cyclotrons had been started up in various places, many capable physicists had immigrated, and the interest in nuclear physics even on the part of the public was very great. Our proposition that the physicists on both sides should not advance the production of atomic bombs was thus indirectly, if one wants to exaggerate the point, a proposition in favor of Hitler. The instinctive human position “As a decent human being one cannot make atomic weapons” thus coincided with an advantage for Germany.

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.”