Copenhagen (8 page)

Heisenberg
  How did we talk? In Danish?

Bohr
  In German, surely.

Heisenberg
  I lectured in Danish. I had to give my first colloquium when I’d only been here for ten weeks.

Bohr
  I remember it. Your Danish was already excellent.

Heisenberg
  No. You did a terrible thing to me. Half-an-hour before it started you said casually, Oh, I think we’ll speak English today.

Bohr
  But when you explained …?

Heisenberg
  Explain to the Pope? I didn’t dare. That excellent Danish you heard was my first attempt at English.

Bohr
  My dear Heisenberg! On our own together, though? My love, do you recall?

Margrethe
  What language you spoke when I wasn’t there? You think I had microphones hidden?

Bohr
  No, no—but patience, my love, patience!

Margrethe
  Patience?

Bohr
  You sounded a little sharp.

Margrethe
  Not at all.

Bohr
  We have to follow the threads right back to the beginning of the maze.

Margrethe
  I’m watching every step.

Bohr
  You didn’t mind? I hope.

Margrethe
  Mind?

Bohr
  Being left at home?

Margrethe
  While you went off on your hike? Of course not. Why should I have minded? You had to get out of the
house. Two new sons arriving on top of each other would be rather a lot for any man to put up with.

Bohr
  Two new sons?

Margrethe
  Heisenberg.

Bohr
  Yes, yes.

Margrethe
  And our own son.

Bohr
  Aage?

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 …

Heisenberg
  My head began to clear, and I had this very sharp picture of what atomic physics ought to be like. I suddenly realised that we had to limit it to the measurements we could actually make, to what we could actually observe. We can’t see the electrons inside the atom …

Margrethe
  Any more than Niels can see the thoughts in your head, or you the thoughts in Niels’s.

Heisenberg
  All we can see are the effects that the electrons produce, on the light that they reflect …

Bohr
  But the difficulties you were trying to resolve were the ones we’d explored together, over dinner in the flat, on the beach at Tisvilde.

Heisenberg
  Of course. But I remember the evening when the mathematics first began to chime with the principle.

Margrethe
  On Heligoland.

Heisenberg
  On Heligoland.

Margrethe
  On your own.

Heisenberg
  It was terribly laborious—I didn’t understand matrix calculus then … I get so excited I keep making mistakes. But by three in the morning I’ve got it. I seem to be looking through the surface of atomic phenomena into a strangely beautiful interior world. A world of pure mathematical structures. I’m too excited to sleep. I go down to the southern end of the island. There’s a rock jutting out into the sea that I’ve been longing to
climb. I get up it in the half-light before the dawn, and lie on top, gazing out to sea.

Margrethe
  On your own.

Heisenberg
  On my own. And yes—I was happy.

Margrethe
  Happier than you were back here with us all in Copenhagen the following winter.

Heisenberg
  What, with all the Schrödinger nonsense?

Bohr
  Nonsense? Come, come. Schrödinger’s wave formulation?

Margrethe
  Yes, suddenly everyone’s turned their backs on your wonderful new matrix mechanics.

Heisenberg
  No one can understand it.

Margrethe
  And they
can
understand Schrödinger’s wave mechanics.

Heisenberg
  Because they’d learnt it in school! We’re going backwards to classical physics! And when I’m a little cautious about accepting it …

Bohr
  A little cautious? Not to criticise, but …

Margrethe
   … You described it as repulsive!

Heisenberg
  I said the physical implications were repulsive. Schrödinger said my mathematics were repulsive.

Bohr
  I seem to recall you used the word … well, I won’t repeat it in mixed company.

Heisenberg
  In private. But by that time people had gone crazy.

Margrethe
  They thought you were simply jealous.

Heisenberg
  Someone even suggested some bizarre kind of intellectual snobbery. You got extremely excited.

Bohr
  On your behalf.

Heisenberg
  You invited Schrödinger here …

Bohr
  To have a calm debate about our differences.

Heisenberg
  And you fell on him like a madman. You meet him at the station—of course—and you pitch into him before he’s even got his bags off the train. Then you go on at him from first thing in the morning until last thing at night.

Bohr
  
I
go on?
He
goes on!

Heisenberg
  Because you won’t make the least concession!