Michael Frayn’s “Copenhagen” at the Hampstead Theatre: Excellent Revival Of Iconic Play About The Ethics Of The Atom Bomb

Every day, for many weeks, we keep hearing about nuclear weapons. Part of the reason for the current attack on Iran by the United States and Israel is the idea, whether true or not, that the Supreme Leader is building an atom bomb. Or worse. So this revival of Copenhagen, Michael Frayn’s 1998 classic about the race to acquire nuclear weapons during the second world war, definitely feels relevant — even urgent. It’s also a fascinating play about quantum physics, historical certainty (or, rather, uncertainty) and ethical choices. Oh, and this time it stars Richard Schiff, familiar from the equally iconic television series, The West Wing.

Set in the afterlife after all the characters have passed away, the plot focuses on the meeting, in Nazi-occupied Copenhagen in 1941, of two theoretical physicists: German Werner Heisenberg and his older former mentor Niels Bohr (Schiff), who is Jewish. To answer the question of why Heisenberg — head of the Nazi nuclear programme — visited Bohr, and what the two men discussed on one of their short walks, Frayn offers different versions of their meeting, and adds Margrethe, Bohr’s wife, who in real life didn’t like Heisenberg and, in this fictional drama, is a much-needed critical voice.

To this day, it remains uncertain what the two men discussed. Of course, “uncertain” is a word which echoes the usual translation of Heisenberg’s uncertainty principle of 1927, his insight that in quantum mechanics it is fundamentally impossible to measure both the exact position and exact momentum of a quantum particle simultaneously. Frayn applies this idea to show how difficult it is to reconstruct a historical event, especially when neither Heisenberg nor Bohr could agree on what had happened, and when both changed their minds over the years, especially after the end of the war. So the questions multiply.

Was the German trying to influence the eminent Dane to persuade the Americans not to build a nuclear weapon? Or was Heisenberg trying to impress his Nazi masters of his loyalty by finding out about the Allied war effort, and maybe even getting some clues about how such a bomb could work? Was he acting in good faith, trying to find a way towards peace, or acting in a nationalistic frame of mind? The whole question of why the Nazi war effort ultimately failed, when the Americans succeeded, gets various answers here: perhaps the Germans failed to make the right mathematical calculations, or perhaps they simply couldn’t find enough uranium-235 and plutonium-239 to cause the chain reaction needed for a huge explosion. Did Heisenberg actually divert the Nazi war effort into safer channels?

Although this atmosphere of uncertainty gives the play its particular, and compellingly cerebral, dynamic, as the characters act out, and then redraft various possible memories of what happened, some of the historical material is deeply resonant. The reason that so many German theoretical physicists were Jewish is that the anti-Semitic Nazis barred them from other aspects of physics research, and of course persecution meant that they fled Germany, and Bohr eventually left Denmark, finally ending up at Los Alamos. Here, under the leadership of J Robert Oppenheimer, they developed the bombs that were dropped on Hiroshima and Nagasaki in 1945. This means that Nazi anti-Semitism resulted in Germany’s failure to create nuclear weapons — and they lost the war.

Frayn’s play carries echoes not only of Tom Stoppard’s Arcadia, with its ideas about chaos theory, but also of Jean-Paul Sartre’s Huis clos (No Way Out), whose three characters are trapped together for all eternity. The presence of Margrethe encourages the men to explain their theories in everyday language, but the result is still quite challenging. The main takeaway is a feeling of dizzy wonder about the sub-atomic world, buzzing with electrons, waves and moments of captured light. As every observation influences the object being observed, this insight has a metaphorical resonance, especially when Heisenberg, after Germany’s surrender, is interrogated at Farm Hall in England — his every conversation spied on and recorded. Knowing this, he may not always have told the truth.

The other vibe that comes across strongly throughout Copenhagen is its demonstration of how modern science is a collective enterprise. Time and again, other physicists are mentioned, such as Wolfgang Pauli, Otto Hahn, Victor Weisskopf and Carl Friedrich von Weizäcker, and their arguments and agreements are articulated, the process of publishing research is discussed and the way that a professional interpretive community is created is shown. There’s a humorous enactment of Schrödinger’s cat, and of particles colliding. Other amusing passages include the characterization of Bohr as “the Pope”, and an instance of bluffing yourself in a game of poker.

Margrethe, about whom little is known, gets some of the best lines, from her incisive criticisms of Heisenberg (“You want to save the honour of German science”) to the passionate insight that “I look around me and what I see isn’t a story. It’s confusion and rage and jealousy and tears and no one knowing what things mean”. Exactly. History is a form of fictional narrative. As the characters replay Heisenberg’s visit over and over, moments of clarity are jumbled up with hazy memories. Yet some images stand out: the ruins of Berlin, which today evoke the destruction of Gaza; Bohr’s escape in a fishing boat and the description of fascism as “the darkness of the human soul”.

Frayn’s text is very rich, as are his postscripts in the published playtext, and the amount of material feels not only fascinating, but almost too much. So there are insights into quantum mechanics as humanism, the struggle for self-understanding, plus mentions of Einstein, and the amazing wartime escape of Denmark’s Jews. The metaphor of reckless skiing recurs more than once, and the family tragedy of a drowned child also keeps coming up. In the end, one takeaway is the question of how far scientists are responsible for their creations, and to this of course there is no neat answer.

Michael Longhurst’s production, beautifully designed with hanging lightbulb lanterns by Joanna Scotcher, is reminiscent of his West End staging of Nick Payne’s Constellations in 2021. His cast is very good: Schiff gives Bohr a parental, father-like gravity, but also his characteristic hesitant, thoughtful, articulacy, while Alex Kingston’s Margrethe pointedly punctures the male egos around her, and delivers some superbly timed insights. By contrast, Damien Molony is suitably nervy as the unreliable narrator Heisenberg, while still having a good deal of charm. A thrilling revival of a play that continues to speak to us today.

• Copenhagen is at the Hampstead Theatre until 2 May.