Bohr was Danish, Heisenberg German. They became friends in the 1920s. Bohr became the "pope" of quantum theory by virtue of his slow, deep-thinking mind; Heisenberg was a skittish younger cardinal. By the '40s their governments had begun courting and keeping track of them, largely because the outcome of Hitler's war depended, or seemed to depend, on the atom bomb. One day in 1941 Heisenberg paid a mysterious visit to Niels and his wife Margarethe Bohr at their house near Copenhagen, and the Bohrs wondered if he was a spy. At the very least, the Nazis would debrief him on his return home. Bohr had to watch his tongue, and (in Frayn's conception) certain future-determining things were left unsaid.
The meeting in Copenhagen has been argued about so often that any reconstruction behaves according to its own uncertainty principle, so Frayn lets his characters hash out the story from beyond the grave. He puts the two scientists and Mrs. Bohr in a stark, circular, marble-walled limbo -- a kind of Olympus for physicists -- where they revisit motives, loyalties, and careers. This arrangement has the disadvantage of forcing the actors to narrate. "So here I am," says Heisenberg, striding across bare marble, "walking out in the twilight to Niels Bohr's house." It's a huge burden on the actors. They have to discuss history and quantum physics in a way that introduces the audience to the details of World War II but that also resembles normal conversation. That's an impossible burden, actually, but the visible strain of it dissolves after half an hour.
What doesn't dissolve is the strain on the audience. Copenhagen is all talk, laced with humor but mostly concerned with a grim race for nuclear power. It's a Shaw play without the lively conversation. Listening to Heisenberg and Bohr and Margarethe discuss the war is not like going to the theater; it's like going to class, and a good part of the audience on opening night was nodding off.
Still, I like a good lecture, and Copenhagen qualifies. Heisenberg starts as a villain -- a Nazi collaborator, if not a spy -- which is more or less how he's been viewed since the war. We know that Bohr broke off the meeting as soon as Heisenberg brought up nuclear fission, because moral or technical advice on the bomb was out of the question. But in this afterlife Heisenberg gets to defend himself. He didn't want advice on building a bomb, he says, but on not building it: Heisenberg stayed on as chair of the team in Germany to block an eager Nazi from usurping the project. Slowly Heisenberg's colors change, until he looks like a hero -- and even accuses Bohr of midwifing an actual monster, the one that exploded over Japan.
Soon his colors shift back, though, and Frayn explores the question of Heisenberg's role in the war with a sure and subtle eye. He's not afraid to separate the physicist's native reluctance to lead Germany to ruin from his willed resistance to Hitler. Heisenberg is a shifty character -- an uncertainty principle applies to his legacy, too, and Frayn wants to elaborate it into a metaphor. "When we look into ourselves we do come up against limitations on what we can observe and know," he writes in the program notes, "that are not entirely unlike the barriers that he and Bohr had established as restricting our knowledge of events inside the atom." But the metaphor is best seen intellectually, from a distance; it doesn't radiate brilliantly from the stage.
I'm not sure why Copenhagen has won so many awards. Maybe the actors were stronger in London and New York. Len Cariou plays a stout, grandfatherly Bohr (although Bohr was thin), vacillating nicely between friendship and mistrust. Mariette Hartley is a composed, intelligent Margarethe who rises to eloquence in a speech about the men romanticizing their past. But neither of them transcends the formal, large-house acting that Frayn's script demands, and Hank Stratton seems especially bland as Heisenberg. It's not that he fails to present the physicist as a nervously two-sided man -- he does -- but the real Heisenberg had a clear, sharp-eyed persona, for all his contradictions. Stratton might as well not be there at all.