Dr Faustus of Modern Physics - Department of Speech, Music and ...

Chapter 43
Copenhagen Play
Copenhagen is a play by Michael Frayn, based around an event that occurred
in Copenhagen in 1941, a meeting between Bohr and Heisenberg, which debuted
in London in 1998. It ran for more than 300 performances at the
National Theatre in London and opened on Broadway at the Royale Theatre
on April 11, 2000 and ran for 326 performances.
The play is about the development of the atomic bomb during the 2nd
World War: Bohr left Denmark for the US to join the Manhattan project
leading to the bombs over Hiroshima and Nagasaki, while Heisenberg remained
in Germany and (according to the play) discouraged German war
effeorts from constructing a bomb.
Theatrically, the most dramatic moment in the play occurs as Heisenberg,
at Bohr’s urging, performs the crucial calculation for the critical mass of U-
235 that would have given Germany the key to the bomb:
Bohr: Why are you confident that it is going to be so reassuringly difficult
to build a bomb with 235? Is it because you’ve done the calculation?
Heisenberg: The calculation?
Bohr: Of the diffusion in 235. No, it’s because you haven’t calculated it.
You haven’t considered calculating it. You hadn’t consciously realized there
was a calculation to be made.
Heisenberg: And of course now I have realized. In fact it wouldn’t be all
that difficult. Let’s see t he scattering cross-section is s about 6 x 10-24, so
the mean free path would be , Hold on...
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