The idea that we deviate from the path we are on - because of choice, chance or some sort of determinism - is one that British master dramatist and author Michael Frayn has long explored.
It threads through Frayn's 1998 play Copenhagen, which, following an international trend to revive many of his plays, gets an Auckland staging next week courtesy of recently arrived English director Alex Bonham and actors Jennifer Ward-Lealand, Bruce Phillips and Simon Kane.
Based on murky real-life events long argued over by historians and scientists, the award-winning drama revolves round a 1941 meeting between Werner Heisenberg (Kane), one of the scientists leading Nazi Germany's nuclear energy project, and his friend, mentor and fellow physicist Niels Bohr (Phillips), in occupied Denmark.
Exactly what Heisenberg's motivations were remain unclear, not helped by the fact that the protagonists, fearing they were being monitored by the Gestapo, talked to one another carefully and cryptically. Did he want Bohr to help him develop an atomic bomb so Germany could drop one on London, did he want moral guidance, or did he want the older man to know what might lie ahead so he could try to stop it?
In true post-modern style, Copenhagen explores what he might have been seeking by bringing together after their death the spirits of Heisenberg, Bohr and the latter's wife Margrethe, who acts as a sort of spectral witness, opening the play by asking, "Why did he come to Copenhagen?' and watching, commenting on from time to time, what the men are discussing and debating.
Ward-Lealand says of all the characters she has played, this is the one who has to listen with the keenest ears and interpret in the sharpest possible way.
"I don't think I have had a piece that is so packed with ideas. Each role is complex in its own way, but I don't think I have played a character so closely involved with the creation of such a huge and potentially world-changing idea."
Each character sees things differently and they proffer their own versions of what took place. If they feel a re-telling of the meeting is wrong, they call for "another draft" and the story takes on a fresh perspective. Along the way, there is lively discussion about nuclear physics and the morality of scientists developing atomic bombs.
Bonham and the cast acknowledge there is a lot of talk about physics, but say Frayn makes the science accessible and relevant so Copenhagen becomes a human story about moral dilemmas and how fate can depend on what a person chooses not to do as much as the actions they do take.
Dr Cather Simpson, a senior lecturer in Auckland University's Department of Physics, helped the cast get to grips with the scientific concepts. Phillips says Simpson's input has been invaluable, further personalising and bringing to life the science behind the play. As Kane says, if the actors have a clear understanding, it makes the play and its themes more real for an audience.
Bonham saw Copenhagen 11 years ago and says the "fiercely intelligent" play changed her life. It made her see the world in a different light and think more deeply about the impact of making a conscious decision not to do something.
Where & when: Tapac, Western Springs, May 31-June 10