Written by Michael Frayn, Copenhagen is a two-act play based on a real-life meeting between physicists Niels Bohr and Werner Heisenberg in 1941. Although based on real events, the play is nonlinear, as its three characters (Bohr, Heisenberg, and Bohr’s wife Margrethe) reunite after death to relive and better understand that fateful meeting. First performed in 1998, the play has won numerous awards, including a Tony Award for Best Play. The play was also adapted into a film in 2002.

Plot Summary

After their deaths, the spirits of Margrethe and Niels Bohr and Werner Heisenberg meet to try and remember why Heisenberg traveled to Copenhagen in 1941. The meeting’s purpose has become obscured over time, though its fallout was felt for many years. With Denmark under Nazi occupation at the time, it was difficult to arrange. The meeting represented the end of the famous friendship and working relationship between the two celebrated physicists, Bohr and Heisenberg.

Heisenberg is aware that he is being closely monitored by the Gestapo. His presence in Denmark is difficult for Bohr; despite their past friendship, meeting with a famous Nazi will brand Bohr as a collaborator among his fellow Danes. Both men remember the walks they took together, so they may do so again if they need to speak privately. Heisenberg arrives at the Bohr house for dinner. The trio make small talk and try to avoid the awkwardness of the circumstances. At times the talk becomes a little too political, and Margrethe tries to steer the conversation in more socially acceptable directions. The two men share memories of fellow scientists and skiing vacations. Next, they talk about friends and children who are alive and who are dead. The two men take their walk. Though Margrethe expects them to be gone for hours, they return quickly and Bohr seems agitated. Heisenberg thanks Margrethe and then leaves.

Margrethe tries to figure out what was said between Heisenberg and her husband—they had been talking about the atomic bomb project but the exact details are not clear. Remembering the meeting, Heisenberg says that he asked Bohr whether a physicist “had the moral right to work on the practical exploitation of atomic energy” (25). Bohr was horrified. The spirits try and piece together the exact details of the conversation, but it seems clear that both men had misread the other’s intentions, leading to muddled recollections about the combative meeting. The men agree to start over from the beginning. Heisenberg admits that he worked on the atomic project for the Nazis but had hoped to slow down and scupper the program. At their meeting, Heisenberg may have been seeking confirmation from Bohr that the Americans had an equivalent project. Bohr said nothing but worked on the American project in later years. He was hailed as a hero while Heisenberg was reviled by many. Still lacking clarity about the meeting, both men agree to return to the beginning.

The spirits remember Heisenberg’s first visit to Copenhagen in 1924. He became Bohr’s assistant, and the two shared many long walks together. Though the two men believe they accomplished great things together, Margrethe points out that their greatest accomplishments came when they were apart. Bohr says Heisenberg focused too much on the mathematics, while Heisenberg accuses Bohr of being obsessed with the paradoxes and contradictions that surrounded their work. They discuss Heisenberg’s rivalry with Schrodinger and how Heisenberg beat him to a university position; Margrethe wonders whether Heisenberg’s trip to Copenhagen was to show off his success. She tells him that he is no hero of the resistance against the Nazis; he may have told himself that he was trying to ruin the atomic project, but he was truly fascinated by the science. Though she views Heisenberg like a son, she admits that he infuriates her.

They discuss whether Heisenberg ever truly figured out the secret to making an atomic bomb. Bohr is not sure, but Heisenberg believes he did and kept it a secret. Unable to find an answer, they return again to the meeting in 1941. This time, Heisenberg sees himself from an exterior perspective. This time, Bohr wonders what would have happened if he had reacted differently. All of his hypotheses end in death and destruction. Next, he recalls how he fled Denmark with the other Danish Jews. The person who helped them was German, an associate of Heisenberg. Heisenberg denies any involvement. Bohr ruminates on his involvement in the American atomic project and his responsibility for the thousands of deaths it caused. Margrethe and Heisenberg agree that he did nothing wrong. Heisenberg recalls traveling through a ruined Germany toward the end of the war. They wonder what the world will be like when they die, but Heisenberg sees the world preserved by the moment in Copenhagen, “by some event that will never quite be located or defined” (58).