Michael Frayn - Copenhagen

Margrethe Ernest!

Bohr 1924—of course — Ernest.

Margrethe Number five. Yes?

Bohr Yes, yes, yes. And if it was March, you’re right — he couldn’t have been much more than …

Margrethe One week.

Bohr One week? One week, yes. And you really didn’t mind?

Margrethe Not at all. I was pleased you had an excuse to get away. And you always went off hiking with your new assistants. You went off with Kramers, when he arrived in 1916.

Bohr Yes, when I suppose Christian was still only …

Margrethe One week.

Bohr Yes.… Yes.… I almost killed Kramers, you know.

Heisenberg Not with a cap-pistol?

Bohr With a mine. On our walk.

Heisenberg Oh, the mine. Yes, you told me, on ours. Never mind Kramers — you almost killed yourself!

Bohr A mine washed up in the shallows …

Heisenberg And of course at once they compete to throw stones at it. What were you thinking of?

Bohr I’ve no idea.

Heisenberg A touch of Elsinore there, perhaps.

Bohr Elsinore?

Heisenberg The darkness inside the human soul.

Bohr You did something just as idiotic.

Heisenberg I did?

Bohr With Dirac in Japan. You climbed a pagoda.

Heisenberg Oh, the pagoda.

Bohr Then balanced on the pinnacle. According to Dirac. On one foot. In a high wind. I’m glad I wasn’t there.

Heisenberg Elsinore, I confess.

Bohr Elsinore, certainly.

Heisenberg I was jealous of Kramers, you know.

Bohr His Eminence. Isn’t that what you called him?

Heisenberg Because that’s what he was. Your leading cardinal. Your favourite son. Till I arrived on the scene.

Margrethe He was a wonderful cellist.

Bohr He was a wonderful everything.

Heisenberg Far too wonderful.

Margrethe I liked him.

Heisenberg I was terrified of him. When I first started at the Institute. I was terrified of all of them. All the boy wonders you had here — they were all so brilliant and accomplished. But Kramers was the heir apparent. All the rest of us had to work in the general study hall. Kramers had the private office next to yours, like the electron on the inmost orbit around the nucleus. And he didn’t think much of my physics. He insisted you could explain everything about the atom by classical mechanics.

Bohr Well, he was wrong.

Margrethe And very soon the private office was vacant.

Bohr And there was another electron on the inmost orbit.

Heisenberg Yes, and for three years we lived inside the atom.

Bohr With other electrons on the outer orbits around us all over Europe.

Heisenberg Max Born and Pascual Jordan in Göttingen.

Bohr Yes, but Schrödinger in Zurich, Fermi in Rome.

Heisenberg Chadwick and Dirac in England.

Bohr Joliot and de Broglie in Paris.

Heisenberg Gamow and Landau in Russia.

Bohr Everyone in and out of each other’s departments.

Heisenberg Papers and drafts of papers on every international mail-train.

Bohr You remember when Goudsmit and Uhlenbeck did spin?

Heisenberg There’s this one last variable in the quantum state of the atom that no one can make sense of. The last hurdle …

Bohr And these two crazy Dutchmen go back to a ridiculous idea that electrons can spin in different ways.

Heisenberg And of course the first thing that everyone wants to know is, What line is Copenhagen going to take?

Bohr I’m on my way to Leiden, as it happens.

Heisenberg And it turns into a papal progress! The train stops on the way at Hamburg …

Bohr Pauli and Stern are waiting on the platform to ask me what I think about spin.

Heisenberg You tell them it’s wrong.

Bohr No, I tell them it’s very …

Heisenberg Interesting.

Bohr I think that is precisely the word I choose.

Heisenberg Then the train pulls into Leiden.

Bohr And I’m met at the barrier by Einstein and Ehrenfest. And I change my mind because Einstein — Einstein, you see? — I’m the Pope — he’s God — because Einstein has made a relativistic analysis, and it resolves all my doubts.

Heisenberg Meanwhile I’m standing in for Max Born at Göttingen, so you make a detour there on your way home.

Bohr And you and Jordan meet me at the station.

Heisenberg Same question: what do you think of spin?

Bohr And when the train stops at Berlin there’s Pauli on the platform.

Heisenberg Wolfgang Pauli, who never gets out of bed if he can possibly avoid it …

Bohr And who’s already met me once at Hamburg on the journey out …

Heisenberg He’s travelled all the way from Hamburg to Berlin purely in order to see you for the second time round …

Bohr And find out how my ideas on spin have developed en route.

Heisenberg Oh, those years! Those amazing years! Those three short years!

Bohr From 1924 to 1927.

Heisenberg From when I arrived in Copenhagen to work with you …

Bohr To when you departed, to take up your chair at Leipzig.

Heisenberg Three years of raw, bracing northern springtime.

Bohr At the end of which we had quantum mechanics, we had uncertainty …

Heisenberg We had complementarity …

Bohr We had the whole Copenhagen Interpretation.

Heisenberg Europe in all its glory again. A new Enlightenment, with Germany back in her rightful place at the heart of it. And who led the way for everyone else?

Margrethe You and Niels.

Heisenberg Well, we did.

Bohr We did.

Margrethe And that’s what you were trying to get back to in 1941?

Heisenberg To something we did in those three years.… Something we said, something we thought.… I keep almost seeing it out of the corner of my eye as we talk! Something about the way we worked. Something about the way we did all those things …

Bohr Together.

Heisenberg Together. Yes, together.

Margrethe No.

Bohr No? What do you mean, no?

Margrethe Not together. You didn’t do any of those things together.

Bohr Yes, we did. Of course we did.

Margrethe No, you didn’t. Every single one of them you did when you were apart. You first worked out quantum mechanics on Heligoland.

Heisenberg Well, it was summer by then. I had my hay fever.

Margrethe And on Heligoland, on your own, on a rocky bare island in the middle of the North Sea, you said there was nothing to distract you …