Copenhagen, Theatre Royal Bath, review: Nazis, atomic physics and an enduring mystery

If you’re going to put any Michael Frayn play on the stage, amid the chronic uncertainty around theatrical activity, then it seems most appropriate to reach for that copper-bottomed modern classic, Copenhagen. It entails three actors, no singing or dancing, and enough food for thought to ensure that the audience members at Theatre Royal Bath would be stocked up if the shutters came down again.

An insistently cerebral, near-sepulchral affair, it handles the real-life 1941 encounter in the Nazi-occupied Danish capital between theoretical physicists Werner Heisenberg and his ex-mentor Niels Bohr (with the latter’s wife Margrethe a crucial figure too). The riddle at its core, concerning what was said at that mysterious meeting, is explored through overt reference – both in terms of the scientific discourse and the slippery drama – to Heisenberg’s “Uncertainty Principle”. (Crudely put: to apprehend a particle, you might also need to view it as a wave, but it can’t be both.)

The frustration and fascination of the play is that you emerge both steeped in the subject and little the wiser as to what took place between Heisenberg and Bohr – or why they met at all. What was the former trying to achieve in approaching the latter (a Dane and half-Jewish)? Since the play’s premiere in 1998, it has emerged that Bohr was left convinced that Heisenberg was helping the Nazis to develop atomic weapons. Frayn then enlarges on these contested specifics to encompass vast thoughts on the nature of existence itself.

This production was twice delayed by lockdowns, hence a double directing credit – Polly Findlay and Emma Howlett. But having seen the Chichester revival of 2018, watching it feels like picking up where I left off three years ago. Back again we go to that rendezvous in Bohr’s house, the opening query by Haydn Gwynne’s bright, poised and aloof Margrethe – “But why?” – setting off a chain-reaction of re-enacted conversations in an eerie afterlife. The trio pore three times over their past words and actions, offering fresh “drafts” of how things went.

Frayn audaciously, and still controversially, gives Heisenberg (an animated, restless Philip Arditti) the case for the defence – arguing that he sought the protection of his beloved homeland, irrespective of its being ruled by the Nazi regime. Even though such involvement makes him a damnable figure, the question remains: why did he brief his old friend (an upright, sage Malcolm Sinclair) on the weapons programme, even on the sly? To fish for information? To pool knowledge? Both?

The clinically precise direction, and the design by Alex Eales, emphasise the circular nature of the confab and give proceedings a sheen of atomic activity: carefully spaced actors and strategically dotted period furniture shift into new configurations via a stage-revolve. That’s not a new approach, but it works, staving off the stasis of a scholastic talking-shop. Yes, the exhaustive probing courts an air of interminability. But in the week that the Biden-Putin summit is reminding us of the atomic pioneers’ terrifying legacy, Copenhagen’s timelessness and timeliness both ultimately prevail.

Until June 26, then touring. Tickets: theatreroyal.org.uk; 01225 448844