According to classical physics, the universe could be imagined as a giant billiards table. An indeterminate number of years ago, some great force broke the ball rack with a giant pool cue. Since then, the billiard balls — the particles that make up the stars and you and me and all the planets we can see — have been in motion, bouncing off of one another according to a strict set of physical laws. Their behavior is predictable. If you were sufficiently wise and sufficiently skilled in math, you could tally together the size, speed, composition, location, and trajectory of every billiard ball in the universe, all the way back to the Big Break or as far into the future as you wished.
Now consider ordinary drama: Something happens in a playwright's imaginary universe, and he transcribes it. A director receives this information and transmits it to actors, a stage manager, a lighting designer, and what have you. These intermediaries then transmit the information yet again to an audience, and then to another. If you were sufficiently wise and sufficiently empathetic, you could tally together the words of a playwright's script and the combined efforts of a theater's personnel and see as deeply into a play as you wished.
Werner Heisenberg and Niels Bohr, the real-life quantum physics pioneers and Nobel laureates about whom Copenhagen was written, wrought havoc on classical Newtonian physics, announcing limits on what is knowable with at least as much finality as their colleague, Albert Einstein, declared the speed limit of the universe. In tribute to them as well as to his own cleverness, playwright Michael Frayn similarly wrought havoc on ordinary drama with Copenhagen. He was rewarded for his efforts with a Tony Award for Best Play in 1998.
In real life, Heisenberg (portrayed by Christopher Oden in the play), a German, helped the Nazis work on a nuclear bomb. Bohr (Colin McPhillamy), a Dane with no particular love for his German occupiers, helped the British do likewise. At the end of September 1941, the old, estranged friends met at the home of Bohr and his wife, Margrethe (Elizabeth Dimon). The men exchanged pleasantries and went for a walk — perhaps to escape any bugs that the SS may have secreted in Bohr's house.
Generations of historians have speculated on what was said at that now-legendary meeting. Before their deaths, both men offered tantalizingly opaque accounts. Copenhagen explores what may have transpired. It is a known fact that their walk was aborted when the two old friends began to argue.
History, Frayn suggests, may turn on such arguments. Copenhagen takes place not in Bohr's home nor even in Copenhagen but in a kind of afterlife where Heisenberg, Bohr, and Margrethe reunite, as puzzled by their meeting in 1941 as the historians who followed them. Applying theories of quantum mechanics, Heisenberg describes photons passing through a cloud chamber as "not a continuous track but a series of glimpses." Mirroring that idea, the main characters' stories cohere in just a few moments — when Heisenberg arrives, for example, or when Bohr angrily terminates the meeting. Using the information at hand, they try to reconstruct the evening, time and again, until they get it right.
There is something spooky in how they set about it. McPhillamy and Oden have done a splendid job of re-creating the personages of Heisenberg and Bohr, especially given the scarcity of good archival footage of the scientists in those years. Bohr was a stoic who expressed emotion not with his body but with his fat lower lip: Sometimes, McPhillamy concentrates so much feeling into that body part that it look ready to leap off his face and wrap itself around Oden's throat. Oden captures Heisenberg's slipperiness, the characteristic tenderness that always seemed just a tad self-serving. He comes off like the world's charmingest, sincerest weasel. Elizabeth Dimon, having even less source material to draw on than the men, turns Margrethe into a plain cipher.
That would be a problem if all of the characters weren't, in their own way, ciphers. There is a curious sense of remoteness in each actor's portrayal, as though they are aware that they are not quite living the scenes they depict. Every re-created conversation from that night in 1941 is merely a possible history, and even in the moments of greatest emotion, the actor's faces seem indeterminate, ready to leap from one state to another.
Only the desire to find the truth feels genuine. The stakes are high, because between them, Heisenberg and Bohr probably had enough knowledge to build the bomb. Heisenberg was an intellectual expeditionary, a lusty explorer of concepts; Bohr was methodical and cautious. It has been suggested that part of the reason J. Robert Oppenheimer eventually succeeded in building the bomb when Heisenberg did not was that Oppenheimer understood, as an engineer might and a theoretician might not, that a chain reaction would be better initiated in a uniform sphere of fissile material than in a cube. There is one scene near the play's end when we get the sense that the world's nuclear future could have rested on far less. Bohr imagines what would have happened if he'd stuffed his anger and really spoken to his old friend.
"Why are you so confident that it's going to be so reassuringly difficult to build a bomb with [Uranium] 235?" asks Bohr. "Is it because you've done the calculation?"
"The calculation?"
"Of the diffusion in 235," Bohr says plainly. Then it dawns on him: His friend's been scientifically stuck precisely "because you haven't calculated it..."
Heisenberg suddenly realizes: "And of course now I have realized. In fact, it wouldn't be all that difficult!" Then he talks to himself excitedly, back on his walk with Bohr. "Let's see... the scattering cross-section's about six by ten to the negative 24th..." And thus Hitler's Germans might have beaten the Americans to the atomic bomb.
Bohr, addressing the audience, speaks over Heisenberg: "And suddenly a very different and very terrible new world begins to take shape..." Then the theater fills with light and thunder.
