Copenhagen by Michael Frayn

First published: 1998

First produced: 1998, at the Royal National Theater, London

Type of plot: History; problem play

Time of work: September, 1941

Locale: The home of Niels and Margrethe Bohr, Copenhagen, Denmark

Principal Characters:

• Werner Heisenberg, a famous German atomic physicist
• Niels Bohr, a famous Danish atomic physicist and Heisenberg’s former mentor
• Margrethe Bohr, Niels’s wife

The Play

The action of Copenhagen concerns a visit made by the German physicist Werner Heisenberg to the Copenhagen home of Niels Bohr in September, 1941. The play is actually several retellings of the same event, with variations in each telling. As the play opens, Bohr and his wife Margrethe are inside their house discussing the reasons for Heisenberg’s visit. Exposition makes it immediately clear that all three characters in the play have long been dead, and that they are reliving the events of the visit. World War II is raging, and the Germans are occupying Denmark. Heisenberg had once been an associate at Bohr’s famous Institute for Theoretical Physics. Heisenberg’s great achievement was the discovery of quantum mechanics, featuring the uncertainty principle. Together Bohr and Heisenberg worked out the famous Copenhagen interpretation, which argues that all things can only be understood within the context of a human measuring process. Bohr won the Nobel Prize in Physics in 1922. Heisenberg received the same honor in 1932.

As Bohr and his wife discuss the possible reasons for Heisenberg’s journey to Denmark, Heisenberg chats with the audience as he walks toward the house, noting that there has been constant speculation over the past six decades about why he visited Bohr. Margrethe argues with her husband that Heisenberg is coming to get information about how to construct an atomic bomb because Bohr is one of the world’s great experts in the field of atomic fission. Bohr postulates that no one can develop a weapon based on atomic fission because no one yet understands the mathematics. When Heisenberg enters the Bohr residence, the talk is polite and nostalgic. The three chat about their children and their love of skiing. Heisenberg asks Bohr if he might come to Germany to ski; Bohr reminds him that he is half-Jewish and would not be welcome in Germany. They agree that they should stick to discussing physics and not talk of politics, but Heisenberg is moved to point out that the two subjects are often difficult to keep apart. This observation leads Bohr to ask if Heisenberg has come to borrow the cyclotron—an accelerator in which charged particles are propelled by an alternating electric field in a constant magnetic field—of the Danish Institute of Theoretical Physics. At the time it is not clear whether Germany has been able to construct a cyclotron. Hesienberg says he has not.

The reminiscences continue, and the history of early twentieth century atomic physics is rehashed as the two great minds review their discoveries and those of their colleagues. They recall ski trips together and how skiing down a mountain at breakneck speed is a perfect demonstration of the uncertainty principle: If you know how fast you are going, you cannot know just where you are located on the mountain; if you know exactly where you are located, you cannot tell exactly how fast you are going.

When both are in a jovial mood, Heisenberg asks Bohr to take a walk with him. They exit and return shortly. Bohr is obviously upset and Heisenberg leaves immediately. Margrethe questions her husband about what took place on the walk, but he will not reveal details. The ghost of Heisenberg then intrudes to propose that the conversation during their walk was about his question of whether it was moral for a physicist to work on the practical exploitation of atomic energy. A new retelling of the Heisenberg visit is now under way. Bohr says that as he remembers the events, Heisenberg was discussing building an atomic bomb for Adolf Hitler. Heisenberg interjects that he was discussing building an atomic reactor to provide energy to run ships. The two replay their conversation about the morality of building an atomic weapon and argue about their stances. Bohr indicates that it would be especially immoral for Germany to possess the bomb. Heisenberg argues that all weapons of mass destruction are immoral, no matter who possesses them. It is Bohr, after all, who will ultimately aid the Americans in the construction of an atomic bomb. Here act 1 comes to an end.

Act 2 contains other retellings of the Heisenberg visit, in which Heisenberg argues that he deliberately miscalculated the amount of uranium necessary to create an atomic bomb. It is also revealed that Heisenberg may have been the one who helped Bohr escape to the United States, where Bohr did indeed aid in the creation of an atomic bomb. The act ends with a discussion of the possibility of the emergence of a new kind of morality, “quantum morality.”

Dramatic Devices

Copenhagen reflects the images of atomic physics. The home of Niels Bohr is an atomic nucleus, around which Bohr and his wife revolve. They are two particles bombarded by an outside force—the entrance of Werner Heisenberg—which actually bombards the Bohr home several times in several related but different fields, as in an Einsteinian universe. Each time a different reaction is obtained, as in a quantum universe. Thus the play presents a quantum, postmodern universe in which reality is dependent on the context of the energies present and on the way one chooses to measure those energies. The retelling of a single event in which the agreements and antagonisms of the characters change each time is an especially theatrical approach. Literary prose forms may employ multiple retellings, but the impact of the same characters, wearing the same costumes, employing exactly the same scenery, and performing for the same audience would not be as immediate as in theater. Moreover, in both the original London and New York productions, Copenhagen was staged on an arena set in which the audience surrounded the actors, and the only furniture present were three identical chairs moved about to make different configurations. This approach physically reflects the basic pattern of an atomic universe, subject to multiple interpretations depending on the observer’s viewpoint at any given time.

The structure of Copenhagen also suggests the famous “two-slit” experiment, in which a light beam is split and sent simultaneously through two different slits. In one slit the beam is measured as a wave and acts like a wave. In the other slit the beam is measured as a particle and acts like a particle. The conclusion is that if matter is measured as a wave it will act as a wave, but if matter is measured as a particle it will act as a particle. This experiment parallels the secret conversation that takes place during the walk of Bohr and Heisenberg: The matter discussed acts one way according to Heisenberg and another way according to Bohr. Each of their wave functions subsequently collapses, only to be replaced by another, third function. Because of the multiple collapsing of wave functions, the structure of Copenhagen also resembles the famous cat-in-the-box thought experiment of Erwin Schrödinger, in which a cat is locked in a box and can elect to get food or poison by triggering the correct energy beam. When the box is opened, the cat is always dead, because the viewer has chosen to see the cat as dead. In Copenhagen, no matter how many times the audience “opens the box” to view the three characters, they are dead and remain dead.

Finally there is no device more ancient and more characteristic of the theater and its drama than the direct address to the audience, a technique that Frayn employs several times for both Margrethe and Heisenberg. In the case of Copenhagen, this device emphasizes the underlying quantum structure of the play in that each character’s direct address to the audience is a form of measuring reality from a personal context in a postmodern world.

Critical Context

Michael Frayn is well known as a novelist, journalist, and playwright. His writings for the theater have been mainly comic, and his highly successful farce Noises Off (pr., pb. 1982) has been an audience favorite since its inception. Copenhagen represents a major departure from his usual fare, but it has been received with great critical acclaim in England and the United States, where it won the Tony Award for best play in 2000. While the most influential sciences of the twenty-first century are arguably the life sciences, the most influential science of the twentieth century was physics. The repercussions of the advancements in physics that led first to relativity, then to new visions of the atom, and ultimately to the creation of the terrifying atomic bomb remain today. Because of the bomb, civilization remains in constant and absolute danger. Copenhagen explores not only the practical issues of weapons of mass destruction but also the consequences of a science of relativity and uncertainty that results in a moral structure of the same quality. In the postmodern world, influenced by the revelations of physics, humanity has to grapple with the issue that all measurement, all human action and belief, must be understood in some particular and unique context. There are no absolutes. This is an overriding modern issue, and the one that pervades Frayn’s Copenhagen. Since its appearance, the play has precipitated the holding of various conferences around the world on the historic and moral problems it raises.

Sources for Further Study

Burns, Lisa Hemphill. “Michael Frayn’s Copenhagen: A Multidimensional Play.” Studies in Education 78 (Winter, 1999-2000).

Flynn, Michael, and Linda Rothstein. “The Real Mystery Science Theater.” Bulletin of the Atomic Scientists 54 (November/December, 1998): 9-10.

Frayn, Michael, and David Burke. The Copenhagen Papers: An Intrigue. New York: Metropolitan Books, 2001.

King, Robert L. “The Play of Ideas.” North American Review 283 (November/December, 1998): 38-42.

King, Robert L. “The Play of Uncertain Ideas.” Massachusetts Review 42 (Summer, 2001): 165-175.

Logan, Jonathan. “A Strange New Quantum Ethics.” American Scientist 88 (July/August, 2000): 356-359.