P E R S O N A L    N O T E S

I have been taking self-reflecting notes while writing The Bomb at Farm Hall; a play that intends to investigate and dramatise the science and politics, the expectations and the fears of an atomic bomb during World War II -- and especially so in Germany. It was necessary to write down my own reflections on the various recordings and readings of the historical events. I needed to gain control over the different interpretations that were later applied to thiese original events.
    It is always the case that we are presented with perspectives and narratives, which we can try to correct for a better or more faithful representation. I have an urge to penetrate and explain what appears mysterious or even incomprehensible. My representation is, of course, just another version in a process that, at best, brings us closer to the reality in which people once lived. What people? Primarily the physicist Werner Heisenberg, but also his American critic and adversary Samuel Goudsmit..

OVERVIEW

2023.0725 ..     Robert Oppenheimer was the central figure in the development of the American atomic bombs used against Japan at the end of World War II. The motive for this effort can be traced back to a letter Einstein sent to the American President Roosevelt in August 1939:
"... In the course of the last four months it has been made probable ... that it may become possible to set up a nuclear chain reaction in a large mass of Uranium by which vast amounts of power would be generated. ... This would also lead to the construction of bombs ...
I understand that Germany has actually stopped the sale of Uranium from the Czechoslovakian mines which she has taken over. That ... might perhaps be understood on the ground that the son of the German Under-Secretary of State, von Weizsäcker, is attached to the Kaiser-Wilhelm-Institut in Berlin where some of the American work on Uranium is now being repeated."
    The somewhat cryptic reference to the physicist Carl Friedrich von Weizsäcker in the letter has the implicit meaning that there is a threat: Germany is developing an atomic weapon. Thus, the motive for the American effort should be sought in Hitler's Germany. Immediately upon the German Hahn-Meitner discovery in 1938 that a Uranium atom could be split, it was clear, both in America and in Germany, that an atomic bomb was possibile to build, at least in theory. At a conference in Germany in 1939, someone raised the question of whether they should even start a bomb project, which was promptly answered by the conference authorities. Walther Bothe stood up and said: "Meine Herren, it must be done!" And Hans Geiger set the agenda: "If there is the slightest chance that it is possible, it must be done!"

In 1942, the large-scale American program to produce an atomic bomb began. At the same time, discussions and decisions were made in Germany about a possible industrial effort. At a conference in July 1942 the leading German physicist Werner Heisenberg explained to the authorities that:
    "Pure Uranium-235 is a substance with almost immeasurable explosive power... Once a reactor has been built, the question of how to obtain an explosive of this magnitude takes an unexpected turn: through a transformation of the reactor's Uranium, a new substance is created, most likely as explosive as Uranium-235." That is Plutonium.
    And here is the mystery: we know that Germany never produced an atomic bomb. Einstein commented in 1947: "had I known that the Germans would not succeed in developing an atomic bomb, I would have done nothing." So, he would not have sent the letter to Roosevelt, thinking that it would have spared the world from atomic bombs. What was happening in Nazi Germany was the counter-point of the massive American effort. But what exactly was going on in Hitler's Germany was not possible to know at the time. Even today it remains complicated -- it is still not entirely clear what would explain the failure of the German ambition of 1939.

For the Americans, it was necessary to gather information about the German efforts during the war. An intelligence field unit, ALSOS, was created, with physicist Samuel Goudsmit as its scientific leader. Only in 1944 did the unit obtain materials giving evidence that the German effort was small-scale and therefore not a serious threat to the Allies. Shortly after the war, Goudsmit wrote a report on ALSOS actions (published in 1948), where he discussed the question of why the Germans failed to develop an atomic bomb.
    Goudsmit's thesis was that the Germans failed scientifically in their calculations of the bomb, especially its size - and that this, in turn, was due to the fact that the Hitler regime appointed an incompetent loyal-to-the-regime leadership, and thus hindered scientific development. Einstein's theory of relativity was not fit for Aryan science, and most importantly, Jewish physicists of the highest caliber fled to the USA, where they participated in the Manhattan Project.

Werner Heisenberg led the German so-called Uranium Club. Several researchers at various universities contributed to a German research program on Uranium. There was also competition within the program; a work-group led by army-appointed Kurt Diebner seems to have had a better implementation of a reactor. But none of them succeeded in initiating a self-sustained nuclear reaction. They lacked sufficient raw material of Uranium and heavy-water to reach a critical mass. An industrial effort to produce a bomb seemed to be beyond reach.
    A question from General Becker at the Defense Ministry (February 1942): "Professor Heisenberg, can you produce a bomb that will decide the outcome of the war within nine months?" The answer: "It is not possible." The same question to Walther Bothe and the same answer. Goudsmit claims that Heisenberg's reason for this assessment was that the German calculated the bomb size to be several tons (the actual figure is 56 kg). And there is information supporting Goudsmit's description.
    Heisenberg and nine other German physicists were interned at the end of the war at Farm Hall in England. They were wiretapped, and the secrecy of the transcripts was lifted in 1992 (although Goudsmit had had access to the transcripts). It was revealed that when they heard the BBC news on August 6, 1945, about the American dropping of an atomic bomb on Hiroshima in Japan, Heisenberg assumed a bomb size of two tons.
    In the same transcripts, there is an oddity: Otto Hahn questioned whether they really needed that much Uranium-235 in a bomb. The remarkable thing is that Hahn then wondered why Heisenberg at the start of the war had said that one only needed 50 kilograms of pure Uranium-235 in a bomb. Heisenberg's reply was that he at this moment did not want to commit himself to a specific number - and that in fact he had never made the calculation!

So, if Goudsmit emphasized the incompetence of the German scientists, especially Heisenberg, others have seen a deeper pattern in what happened. Firstly, Goudsmit seems to be wrong about the Germans' knowledge: it is clear from previous quotes that the Germans were well aware of the conditions for an atomic bomb, either through the enrichment of Uranium-235 or by producing Plutonium in a reactor. The latter approach was used by the aforementioned von Weizsäcker to apply for a bomb patent. To this, the author Thomas Powers adds a piece of the puzzle in a rich and highly readable book: "Heisenberg's War" (1993). Over the years, he has put forth the thesis that Heisenberg and an inner circle of confidants actively obstructed a German bomb project (New York Review of Books).
    What evidence does Powers provide for his thesis? Take Hahn's and other researchers' statements that Heisenberg and Weizsäcker initially claimed that a bomb was feasible. However, when an industrialist, von Ardenne, wanted to develop the technology to separate Uranium-235 from raw ore for a bomb, they changed their stance: a bomb would not be practically feasible. In front of an inner circle, they stated the bomb size as 50 kg - to an outer circle: 2 tons. When Heisenberg at Farm Hall was compelled to report the bomb's size to both the inner and outer circles of physicists, the reported contradiction emerged.
    Furthermore, we have a meeting in 1941 in the German-occupied Copenhagen between physicists Werner Heisenberg and Niels Bohr. Heisenberg has claimed that he wanted to discuss a moratorium on the development of atomic bombs, while Bohr later wrote that he had not perceived the slightest hint of this; on the contrary, Bohr believed that Heisenberg assertively spoke about Germany being in the midst of such a bomb project. The question arises: why did Heisenberg seek out Bohr in the midst of a raging war? Even discussing a German Uranium project with outsiders must be considered to be treachery. Much indicates that Heisenberg was genuinely concerned and deeply worried about the development of atomic bombs and therefore sought out the doyen of quantum physics to see if there was a way to put a stop to it. Could Heisenberg have had moral motives for his actions?

In a conversation with Otto Hahn at Farm Hall, Heisenberg said: "German physicists did not want Hitler to win the war." Publicly, Heisenberg put it this way: "The atomic bomb project was too extensive for a Germany at war." After the war, he added: "This fact spared German physicists a moral decision." The wording has been regarded as an implicit accusation: what moral considerations dictated the American use of a weapon of mass destruction? A still highly sensitive issue (especially in America), which can be obscured by questioning Heisenberg's motives. Goudsmit explained that Heisenberg tried to transform a scientific failure into a moral success.
    Yet, it does not appear impossible to summarize Heisenberg's attitude like this: he did not want to supply Hitler with an atomic bomb, but he also did not want Germany to lose the war. An apparently impossible equation. The almost impossible compromise: for purely rational reasons, he advised German authorities not to develop an atomic bomb. Had he invoked moral reasons, he would have been celebrated by Americans but seen as a traitor by Germans. He barely survived in the post-war period, mostly distrusted, primarily in America. Goudsmit here played the role of a hero.
    Possibly, Heisenberg had tried to win the peace by demonstrating that Germany now had the solution to the world's energy needs - almost. It was a bitter experience to have nothing of scientific value to teach the world, as the Americans had already done it better. But perhaps there was a moral lesson? On the American side, Oppenheimer did not hesitate to meticulously specify the conditions for the maximum impact of the bomb on Hiroshima: weather conditions, the optimal altitude... Afterwards, he grappled with moral doubts: I have blood on my hands; I have become the one who sends death to people: "Now I am become Death, the destroyer of worlds."

HOW I BEGAN WRTING A PLAY ..

#1   A START AT THE LIBRARY:
       Myth, Truth, and the German Atomic Bomb

2006.0127    Yesterday, I visited the KTH library to borrow first of all Samuel Goudsmit's book "Alsos" written in 1947. The library from the 1920s had moved from a magnificent location facing Valhallavägen to a new beautiful glass building. The thing is I had to reorient myself among the new shapes: I was once a student here in the 1960s, at the Aviation Engineering Section. While walking along the passages, I was aware of the fact that the first swedish experimental nuclear reactor was located in the midst of this complex. A nice introduction to the theme of my not so nice project: the German atomic bomb; or rather its failure -- according to Goudsmit. Thus I intend to orient myself in this historical labyrinth.

2006.0128    I start reading the introduction to Samuel Goudsmit's Alsos. Also reading Mark Walker's critical article on Goudsmit, overnight. Overall, I become very skeptical of Goudsmit; his story of the German atomic bomb feels superficial and not trustworthy. But this does not mean that Werner Heisenberg is the hero as featured in Thomas Powers' book Heisenberg's War. The perspective is further broadened when taking into account Jeremy Bernstein's critical review in the introduction to the FarmHall transcripts. Heisenberg's flaws come to light. These are the books I have started with ..
   - Goudsmit, Samuel (1947): Alsos.
   - Walker, Mark (1995): Nazi Science. Myth, Truth, and the German Atomic Bomb.
   - Powers, Thomas (1993): Heisenberg's War
   - Bernstein, Jeremy (1996, 2001): Hitler's Uranium Club; the Secret Recordings at Farm Hall.

---

#2   THE CRITICAL MASS
In this note I discuss the critical mass - which defines the amount of Uranium needed to produce a chain reaction of neutrons, that would cause an atomic explosion. At the beginning of the war scientist had no definit answer to this question.

2006.0129    Early on in the war Heisenberg, Hahn and Weizsäcker had a conversation with Manfred von Ardenne about the size of an atomic bomb. I wanted to check what was reported to have been said – a few kilos or a few tons? In Powers (p.134), the following is presented:
    "In his memoirs Ardenne says he asked ... how much Uran- 235 would be needed to achieve critical mass in a bomb. Heisenberg said `a few kilograms´ were enough /as did Otto Hahn/ ... Ardenne's laboratory had already began work on electromagnetic separation of /Uranium/ isotopes, and he told Hahn he thought separation of a few kilograms of Uranium-235 would be possible with the aid of ... the Siemens company.
    But a few weeks after the visits by Heisenberg and Hahn, early in 1942, Carl Friedrich von Weizsäcker came to see Ardenne and told him that Heisenberg had concluded from new research that a bomb was not feasable after all: ...the multiplication of neutrons would decline and the reaction would fizzle as the rapidly heating mass of U-235 blew itself apart.
    In effect Weizsäcker was passing on Niels Bohr's hopeful `no bomb´ analysis of the problem of 1939. ... /Ardenne/ had no reason to think that Weizsäcker might deliberately lead him astray. The conversation ended Ardenne's interest in fission; even long after the war he believed Heisenberg's `mistake´ had been a genuine one and that it explained the failure of the German bomb program."

But with this quotation another problem becomes apparent: the interpretation of events. Either one assumes that Heisenberg sincerely meant that a bomb was impossible for the reasons he gave to von Ardenne, or one leans towards what Powers suggests: that Heisenberg and Weizsäcker deliberately misled the industrialist.
    Both approaches seem possible. Let me look at contrasting interpretations presented by Powers, and on the other hand Jeremy Bernstein. One can say that they seem to agree that Heisenberg had a negative impact on the development of a German atomic bomb. However, while Powers believes this was due to Heisenberg's political/ moral considerations, Bernstein argues that it was due to Heisenberg's poor decisions and incompetence in experimental/ practical matters.
    Therefore, I must find a reasonable approach to Heisenberg's character. Bernstein's interpretation is based on what Heisenberg initially said at Farm Hall in 1945 just after the BBC radio broadcast of the Hiroshima bombing (1945.0806 at 21:00), regarding the critical mass for example. Bernstein believes that Heisenberg did not display the knowledge required to make an accurate judgment about the bomb's feasibility.
    In Powers' chapters 9-13, there is a detailed description of how Heisenberg and his confidants in 1941 discussed the dilemma of putting a bomb in Hitler's hands. This includes the episode of the visit to Bohr, and Houtermans' warning to America regarding a German bomb program. This suggests that Heisenberg believed a bomb was possible. So, it indicates Ardenne was misled in 1942? Or suppose, again, that Heisenberg in the meantime had made a new calculation that changed the prospects for a bomb.
    The question is also whether one can expect a consistent stance from Heisenberg over time on this critical issue - Bernstein spans the years 1941 to 1945. [ comment: in March 1940 Otto Frisch and Rudolf Peierls in England were the first to suggest the bomb size for pure Uranium-235: a few kilograms. This was overly `optimistic´, but it changed the minds of people involved from impossible to might be possible. The estimated size has varied over time and is today reported to be around 50 kg. ]

---

#3 A CONVERSATION WITH NIELS BOHR
In the war year of 1941, Heisenberg and Weizsäcker traveled to Copenhagen to meet with the quantum physics pioneer Niels Bohr. One intention was to discuss issues related to the new perspectives opened up by the splitting of the uranium atom. Copenhagen was occupied by the Germans, and at the same time, German armies were advancing in the Soviet Union and seemed invincible.

2006.0131    I am reading once again Powers' account of the meeting in September 1941 between Heisenberg and Bohr (P.120-128). Also retrieving Bohr's never-sent letter to Heisenberg about the meeting, written around 1950 and 1962. How should one relate to what Bohr writes?
    -Around 1950:
If anything in my behaviour could suggest alarm, it came from.. the intelligence that, as far as I could understand, Germany was eagerly participating in a race to be first with atomic weapons.
    A quite different matter is that back then and since, I have always had the definite impression that you and Weizsäcker had arranged the symposium at the German Institute and the visit to us to assure that we were not suffering any maltreatment and to try in every way to help us in our dangerous situation.
    -In the 1962 draft letter:
[it was] a [very] difficult situation to meet and talk with someone who, as strongly as you and Weizsäcker did, expressed your confident conviction of a German victory... Of course, we do understand that it may be difficult for you to keep track of how you thought and expressed yourselves at different times during the war... What I particularly think of, though, is the conversation we had in my office at the Institute, and where, because of the topic you brought up, I carefully imprinted every word that was said. It must have made a very strong impression on me that you immediately stated, to begin with, that you felt sure that the war, if it lasted long enough, would be decided by atomic weapons. On the other hand, there was no hint from your side that among German physicists there were efforts to prevent such exploitation of atomic science.

Should one apply the complex interpretive framework that Heisenberg and Weizsäcker spoke with forked tongues, or in other words, in two different discourses:
1/ one that had to be used in public settings, where every word could be used against them by the Gestapo
2/ a private context where the conversing parties could completely trust each other's discretion (what Powers suggests).
Thus, it might the case that Heisenberg failed to convey to Bohr which discourse was in effect at different times.
    -Take, for example, this excerpt from Bohr's letter:
    ...I heard from the others at the Institute that Weizsäcker had expressed how fortunate it would be for the state of science in Germany after the victory if you could contribute significantly to it.
    Here, it can be argued that, Weizsäcker spoke in an official role, not giving his private opinion on things. But supposedly this was not something that the Danish scientists understood.
    Such a benevolent interpretation of what Heisenberg and Weizsäcker actually meant by what they in fact said might perhaps be supported by the fact that after the meeting, Heisenberg expressed disappointment to his wife and to Weizsäcker: he had completely failed to convey to Bohr what he intended to say. This could mean that Heisenberg was not clear enough in his choice of words, possibly using coded language (according to Bohr, in his office where they could have been bugged). Perhaps Bohr was so upset about the German occupation of Denmark that his present attitude made misinterpretations unavoidable. But to assert this kind of agenda requires making the simpler, straightforward interpretation of Bohr's words less plausible.

Could a solution be to divide the play into two parts: a first part that presents the material/dialogues so that the understandings by Bohr-Goudsmit-Bernstein appears obvious. A second part that presents the exact same sequence so that the Heisenberg-Weizsäcker version has the flavour of being obviously correct. To this, I could possibly add an evaluative part: a conversation between Heisenberg and Goudsmit, or Bohr? Or a contemporary figure? In the spirit of a constructive post-modernism? To develop the audience's insights into epistemology?
[note 2016.0616: already done in the play by Frayn: Copenhagen!]

---

#4 THE GENOCIDE WEAPON
Robert Oppenheimer was the scientific leader for the development of the American atomic bomb. The bomb over Hiroshima was a Uranium bomb, while the one over Nagasaki used Plutonium. When the war ended, the American military debated whether to proceed with the development of even more powerful nuclear weapons, the hydrogen bomb. Oppenheimer opposed this.

2006.0202    I read Powers' post-war chapter Thirty-seven; about how to proceed with atomic weapons now that the war was over -- discussions around the development of the even more powerful hydrogen bomb. And discussions on how the victors should proceed with the Nazi-Germany scientists. It touches Robert Oppenheimer's position in this continued weapons development - highlighting the moral dilemma. It all makes me melancholic. Oppenheimer said...
    It is clear that this weapon would bring about the destruction of innumerable lives. It is not a weapon that can be used exclusively for the destruction of military installations.... It carries a policy of exterminating civilian populations.
In plain language: a super bomb that might become a weapon of genocide.
    For this stance, he underwent a secret humiliating interrogation, to ascertain if he was sabotaging the development of the superbomb. It is depressing to see how people create phantoms of others. This applies especially to the American military leadership.
    But Goudsmit also seems self-enclosed. Heisenberg tries to go through the events of the war with him, but never succeeds. Goudsmit hides an unfavourable impression he had of Heisenberg. Again and again, Heisenberg tries to untangle the knot but fails. The same sadly applies to Bohr from the 1941 meeting. None of them confronts Heisenberg with these concealed opinions, and he can never reach them with a response of one kind or another. Their opinions get stuck, and solidify. Powers commendably tries to explain the circumstances surrounding this. A mood of secrecy lingered over everyone's mind after the war, and it was reinforced by an increasing Cold War mentality caused by tension between the Soviet Union and the West.
    It becomes particularly tragic when Goudsmit's and Bohr's never fully illuminated attitude towards Heisenberg et al spreads to the scientific community at large and to the rest of society.

I am trying to understand the theoretical aspects of bomb construction. It seems important if I am to form my own opinion on the significance of the FarmHall protocols. Bernstein's comments on the protocols are intricate. A crucial detail is the critical mass; the amount of uranium required to trigger the bomb. The critical mass is determined by the radius of Uranium-235 when two effects balance: 1/neutron production 2/neutron leakage at the surface. Today, it is believed that a mass of mc=56 kg is required, which corresponds to a radius rc=8.9 cm. But in addition, one must take into account that the overcritical mass will heat up to a gaseous state.

2006.0210    I have now re-read Powers' presentation of Heisenberg. One is, of course, always ready to agree with the latest speaker. Now it remains to compare Powers' conclusions about Heisenberg's wartime motives with Bernstein's (Powers page 452 and Bernstein page 46 and 185). Bernstein's preconception is in line with Goudsmit's, especially in the assessment of Heisenberg's competence as a physicist.

---

#5 GERMAN VICTORY AND GUILT
How did Heisenberg really feel about Germany and Hitler during the war? Did he expect a German victory or a defeat?

2006.0214    I have read (most of) Barbro Eberan's (2002): Vi är inte färdiga med Hitler på länge än (We Won't Be Done with Hitler for a Long Time). Which deals with the issue of guilt. However, from a side perspective: she maps out the innocently guilty - ordinary people. I miss the perspective of those who were surviving agents, from Speer to Heisenberg. How did they go about at the time of war and after? Did they have a different morality during the Hitler period? What happened when they changed view from believing in a German victory to realizing the inevitable and catastrophic defeat?
    Was it perhaps easier for Heisenberg, who at some point said he never believed in a victory? However, compare this to the strange statement in 1944 in Switzerland at Scherrers :
    but it would have been so good if we had won (Es wäre so schön gewesen, wenn wir gewonnen hätten) (Powers p.402/24).
    How should this be interpreted? This "we" - it is difficult to distinguish between Germany and Hitler in this statement. But there are also statements by Heisenberg at the beginning of the war when he didn't believe it would last long; that Germany could never sustain a war on Hitler's terms. This can be compared to the opposite view: Bohr's strong impression from the 1941 meeting where Heisenberg proclaims Germany's imminent victory. A statement that shocked Bohr.
    There are more facts to refer to for the following thesis: Heisenberg believed in Germany's victory in the war, and he also wished for it. Such a thesis raises several questions. It can be interpreted: a German defeat would be a cultural/scientific catastrophe for Germany. He did not want that to happen, but neither did he want a fascist regime – he himself had experienced the effect of such a regime (as a "white Jew"). As a consequence, the following seems to apply: if a German victory was something Heisenberg hoped for, the use of an atomic bomb does not seem to have been part of that. Perhaps he foresaw the bomb's mass-murder effects, something he didn't want to be held responsible for. And perhaps this is what he wanted to discuss with Bohr - in this ambiguous way?

[Comment 2016.0616.. Should one propose three periods for Heisenberg's attitude towards a German victory?
1.. Before the outbreak of war in 1939: Germany lost the First World War - not much chance that the situation was different now.
2.. German attack on the Soviet Union in 1941: Hitler's bold, victorious attack policy (Sudetenland, Czechoslovakia, Austria, Poland, Denmark-Norway), and especially the entry into Paris, seemed to contradict the assumptions in period 1; thus, Heisenberg believes in a German victory, which he expresses in the meeting with Bohr.
3.. The German defeat at Stalingrad, the retreat from Moscow; Heisenberg now understands that Germany will lose the war (the Battle of Stalingrad was fought from August 1942 to February 1943).]

---

(c) Lasse Rabenius