Copenhagen (play)
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Copenhagen is a play by Michael Frayn, based around an event that occurred in Copenhagen in 1941, a meeting between the physicists Niels Bohr and Werner Heisenberg. It debuted in London in 1998. It opened on Broadway at the Royale Theatre on April 11, 2000 and ran for 326 performances. Directed by Michael Blakemore, it starred Philip Bosco (Niels Bohr), Michael Cumpsty (Werner Heisenberg), and Blair Brown (Margrethe Bohr). It won the Tony Award for Best Play, Best Featured Actress in a Play, (Blair Brown), and Best Direction of a Play (Michael Blakemore).
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[edit] The play
The play contains three characters: Heisenberg, Bohr, and Bohr's wife Margrethe. Its temporal and spatial location are intentionally vague, suggesting that the three are spirits in some sort of timeless, ethereal realm, reflecting on past events and interpretations. The characters interact on stage without benefit of written stage direction or set design, and in many ways resemble the photons and particles they discuss in the play – each colliding with the others emotionally and altering the others' paths by their own actions. The original production was staged "in the round," though a stylized, minimalized version of it, and gave the audience a sense of being scientific observers as the "particles" (actors) moved about in a contained space in front of them.
Bohr and Heisenberg were friends and colleagues, with the older Bohr serving as a mentor to Heisenberg. Heisenberg joined Bohr's institute in Copenhagen in the early 1920s and together they were influential in developing quantum theory before World War II, notably the Copenhagen Interpretation. Throughout the play, the characters recount their history of working together. In 1941, Heisenberg was in charge of the German effort to develop atomic energy for practical purposes (possibly including an atomic bomb). Bohr's native Denmark was occupied by Germany, and he was under severe restrictions on what he could work on, and was in a position of potential danger because he was half-Jewish.
At one point in Heisenberg's visit with Bohr, they apparently went outside for a walk so that they could speak without fear of being monitored by the Gestapo. The walk was, however, brief. As a result of something that was said during this walk, the two formerly close companions were never again good friends. The play deals with why Heisenberg had gone to visit Bohr in an occupied country, the potential conversations between Bohr and Heisenberg, and what this visit ultimately signified as to Heisenberg's efforts on behalf of the German war efforts.
The question of why Heisenberg had come to Copenhagen to visit with Bohr is considered in the play, and it is the uncertainty that makes it interesting. Two concepts which Frayn uses as overarching metaphors in the play are the most famous scientific theories associated with Bohr and Heisenberg: Bohr's idea of complementarity (by which a photon can be regarded as both a wave and a particle, depending on how one looks at it) and Heisenberg's idea of the uncertainty principle (by which it is impossible to know the exact momentum and location of a particle at the same time).
Bohr was later smuggled out of Denmark. In the play he thanks Heisenberg for presumably having had a role in the success of his escape, but Heisenberg says he was not influential at that time. Bohr went to work on the Allied effort to produce nuclear weapons at Los Alamos. By the time Germany lost the war in 1945, Heisenberg had almost constructed a self-sustaining chain reaction in a primitive nuclear reactor in a cave, without proper safety equipment. He made it into a zone of Allied occupation and was later moved to Farm Hall, Great Britain, where he and other German scientists were kept under observation as part of an Allied attempt to discover the full extent of the German bomb program.
The play was adapted as a television movie in 2002, with Daniel Craig as Heisenberg, Stephen Rea as Niels Bohr, and Francesca Annis as Margrethe Bohr. The movie substantially cuts down the script of the play, eliminating several recurring themes, and most of the material that established the community of scientists in Copenhagen. It also abandons the abstract staging of the theatrical version in favor of being set in the city of Copenhagen, in Bohr's old house.
Frayn has said the play was inspired by Thomas Powers' book Heisenberg's War: The Secret History of the German Bomb (Knopf, 1993).
[edit] Historical debate
The meeting took place in September 1941 when Bohr and Heisenberg were 55 and 39 respectively. Heisenberg had worked with Bohr in Copenhagen for several years starting in 1924.
Heisenberg historians remain divided over their own interpretations of the event, and the 1998 play put more attention on what had been a previously primarily scholarly discussion. A collection of historical essays provoked by the play was published in English in 2005. [1]
Much of the initial "controversy" resulted from a 1956 letter Heisenberg sent to the journalist Robert Jungk after reading the German edition of Jungk's book Brighter than a Thousand Suns (1956). In the letter, Heisenberg described how he had come to Copenhagen to discuss with Bohr his moral objections toward scientists working on nuclear weapons, but how he had failed to articulate this clearly before the conversation came to a halt. Jungk published an extract from the letter in the Danish edition of the book in 1956 which, out of context, made it look as if Heisenberg was claiming to have purposely derailed the German bomb project on moral grounds. (The letter's whole text shows Heisenberg was careful not to claim this.) [2] Bohr was outraged after reading this extract in his copy of the book, feeling that this was false and that the 1941 meeting had proven to him that Heisenberg was quite happy with producing nuclear weapons for Germany.
After the play inspired numerous scholarly and media debates over the 1941 meeting, the Niels Bohr Archive in Copenhagen released to the public all heretofore sealed documents related to the meeting, a move intended mostly to settle historical arguments over what they contained. Among the documents were the unsent letters Bohr drafted to Heisenberg in 1957 about Jungk's book and other topics. [3].
These drafts proved to be significant in several respects. First, they proved to be relatively consistent with Heisenberg's own recollections of the meeting [4] given to Jungk in 1956, meaning that the course of the conversation can now be fairly well established. Both Bohr and Heisenberg agree that Heisenberg started the visit by stating to Bohr that nuclear weapons were now conceivable. As Heisenberg wrote to Jungk,
"This talk probably started with my question as to whether or not it was right for physicists to devote themselves in wartime to the uranium problem -- as there was the possibility that progress in this sphere could lead to grave consequences in the technique of the war."
Bohr confirms this by writing
"It had to make a very strong impression on me that at the very outset you stated that you felt certain that the war, if it lasted sufficiently long, would be decided with atomic weapons."
Heisenberg repeated his convictions on the technical feasibility of building nuclear weapons. As Heisenberg recalled:
He [Bohr] replied as far as I can remember with a counter-question, "Do you really think that uranium fission could be utilized for the construction of weapons?" I may have replied: "I know that this is in principle possible, but it would require a terrific technical effort, which, one can only hope, cannot be realized in this war. Bohr was shocked by my reply"
Bohr's draft letters are consistent with this:
"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,"
[This point is of interest, because it is at odds with the view of some that Heisenberg's miscalculations had led him to conclude, erroneously, that atomic weapons were not feasible.] According to Bohr's later notes, Heisenberg then told Bohr that he had not come to discuss the technical aspects of the potential weapons:
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 2 years working exclusively on this question.
Unfortunately, because of Heisenberg's concerns about being monitored -- his discussion of any aspects of the nuclear efforts to someone in an occupied country would have been illegal -- his discussion was cryptic. Indeed, Bohr's letters note that Heisenberg spoke "in vague terms" from which Bohr was only able to get an "impression" about Heisenberg's efforts. Bohr wrote of this:
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 behaviour 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.[5]
This circumspect discussion, combined with Bohr's shocked reaction to it, apparently cut off the discussion between the two. Thus, the Bohr letters cannot resolve the question, posed by the Copenhagen play, of what Heisenberg had wanted -- but failed -- to convey to Bohr.
The Bohr letters are significant here, because they do eliminate some of the more sinister motives that had been postulated. For example, in a 1998 book, Heisenberg and the Nazi atomic bomb project: a study in German culture (Berkeley: University of California Press, 1998), Paul Lawrence Rose had speculated that Heisenberg had visited Bohr as "an intelligence-gathering mission." However, the release of Bohr's letters disprove that claim, showing that Heisenberg had not come to elicit information from Bohr, and did not even want to discuss the technical issues of building a bomb:
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 2 years working exclusively on this question.
This shows that Heisenberg wanted to move the discussion into another area of nuclear weapons, not the technology. This passage also appears to counter the arguments of some Heisenberg critics (such as Rose and Bernstein) that Heisenberg's errors in 1940 had mistakenly led him to conclude that building nuclear weapons was not possible.
Finally, the 1957 Bohr draft letters, written 16 years after the meeting itself, suggest a conflict between Bohr and Heisenberg. However, Heisenberg's own letter to his wife, written on the eve of his departure from Copenhagen, provides no hint of a fracture. In it, he related his final evening with Bohr as very pleasant and unremarkable: "Today I was once more, with Weizsaecker, at Bohr's. In many ways this was especially nice, the conversation revolved for a large part of the evening around purely human concerns, Bohr was reading aloud, I played a Mozart Sonata (a-Major)." [6]
In a March 2006 interview [7] Ivan Supek, one of Heisenberg's students and friends, commented that "Copenhagen is a bad play" and that "Frayn mixed up some things". Supek also claimed that actually Weizsäcker was the main figure of the meeting. Allegedly, "Heisenberg and Weizsäcker came to Bohr wearing German army uniforms. Weizsäcker tried to persuade Bohr to mediate for peace between Great Britain and Germany and Heisenberg practically completely relied on his political judgement". Supek received these details in a confidential conversation with Margrethe who thought he would never make them public. Supek however felt it was "his duty to announce these facts so that future generations can know the truth about the Bohr - Heisenberg meeting".
Supek's statements about Bohr's recollection of "the Bohr - Heisenberg meeting" itself mixes up the visit, and in so doing, suggests the reason why the meeting did not achieve its purpose. Because Heisenberg could only visit Bohr in occupied Denmark through, and on behalf of the German government, Heisenberg was obligated to make public lectures on behalf of the Government, that were monitored by German government officials. Heisenberg, however, had hoped to convey his concerns later, during private discussions with Bohr, away from monitors. Heisenberg's contemporaneous letters to his wife, and later correspondence with Jungkt place the private conversation on Wednesday evening during a walk at Bohr's house, outside the presence of Weizsäcker. [8] ("This talk then took place on an evening walk in the city district near Ny-Carlsberg,") [9] ("Late at night I walked under a clear and starry sky through the city, darkened, to Bohr."). That Supek stated that Margrethe believed that Weizsäcker was present -- and that Bohr himself recalled this private meeting as taking place "in my room at the Institute" [10], where Heisenberg and Weizsäcker had made their public statements -- may suggest that Bohr blurred two events, and did not distinguish between the public statements Heisenberg made and the private message Heisenberg hoped to convey to Bohr in private later that evening at Bohr's house.
[edit] See also
- History of nuclear weapons
- Operation Alsos (Postwar attempt to gauge the progress of the German bomb project)
- Manhattan Project (Allied wartime bomb project)
[edit] External links
- BBC site for "Copenhagen" (TV movie edition)
- PBS site for "Copenhagen" (TV movie edition)
- Review from the American Institute of Physics
- Documents relating to the 1941 meeting written by Heisenberg in 1957[broken citation]
- Documents relating to the 1941 meeting released in 2002 by the Niels Bohr Archive
- Internet Broadway Database page for the 2000-1 Broadway performance
- American Repertory Theatre's production, directed by Scott Zigler
- Michael Frayn's Copenhagen in Debate: Historical Essays and Documents on the 1941 Meeting between Niels Bohr and Werner Heisenberg
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