Copenhagen is also a play by
Michael Frayn, directed by
Michael Blakemore.
The play is based on an historic event: a meeting of Neils Bohr and Werner Heisenberg in 1941. It is interesting to note, as the play takes place during WWII, that Bohr was half-Jewish and a citizen of occupied Denmark and Heisenberg was a professor at Leipzig in Germany, and even, unknown to Bohr, Heisenberg had become head of the Nazi regime's project to harness atomic energy.
The play investigates how these men might have felt about the development of nuclear weapons, but more importantly it proposes that the motives, the feelings, and the relationships mankind experience almost have their own Heisenberg Uncertainty Principle that obscures them.