Authors: Michael Frayn
Margrethe
And when you take up your chair at Leipzig you’re how old?
Heisenberg
Twenty-six.
Bohr
The youngest full professor in Germany.
Heisenberg
I mean the Copenhagen Interpretation. The Copenhagen Interpretation works. However we got there, by whatever combination of high principles and low calculation, of most painfully hard thought and most painfully childish tears, it works. It goes on working.
Margrethe
Yes, and why did you both accept the Interpretation in the end? Was it really because you wanted to re-establish humanism?
Bohr
Of course not. It was because it was the only way to explain what the experimenters had observed.
Margrethe
Or was it because now you were becoming a professor you wanted a solidly established doctrine to teach? Because you wanted to have your new ideas publicly endorsed by the head of the church in Copenhagen? And perhaps Niels agreed to endorse them in return for your accepting
his
doctrines. For recognising him as head of the church. And if you want to know why you came to Copenhagen in 1941 I’ll tell you that as well. You’re right—there’s no great mystery about it. You came to show yourself off to us.
Bohr
Margrethe!
Margrethe
No! When he first came in 1924 he was a humble assistant lecturer from a humiliated nation, grateful to have a job. Now here you are, back in triumph—the leading scientist in a nation that’s conquered most of Europe. You’ve come to show us how well you’ve done in life.
Bohr
This is so unlike you!
Margrethe
I’m sorry, but isn’t that really why he’s here? Because he’s burning to let us know that he’s in charge of
some vital piece of secret research. And that even so he’s preserved a lofty moral independence. Preserved it so famously that he’s being watched by the Gestapo. Preserved it so successfully that he’s now also got a wonderfully important moral dilemma to face.
Bohr
Yes, well, now you’re simply working yourself up.
Margrethe
A chain reaction. You tell one painful truth and it leads to two more. And as you frankly admit, you’re going to go back and continue doing precisely what you were doing before, whatever Niels tells you.
Heisenberg
Yes.
Margrethe
Because you wouldn’t dream of giving up such a wonderful opportunity for research.
Heisenberg
Not if I can possibly help it.
Margrethe
Also you want to demonstrate to the Nazis how useful theoretical physics can be. You want to save the honour of German science. You want to be there to reestablish it in all its glory as soon as the war’s over.
Heisenberg
All the same, I don’t tell Speer that the reactor …
Margrethe
… will produce plutonium, no, because you’re afraid of what will happen if the Nazis commit huge resources, and you fail to deliver the bombs. Please don’t try to tell us that you’re a hero of the resistance.
Heisenberg
I’ve never claimed to be a hero.
Margrethe
Your talent is for skiing too fast for anyone to see where you are. For always being in more than one position at a time, like one of your particles.
Heisenberg
I can only say that it worked. Unlike most of the gestures made by heroes of the resistance. It worked! I know what you think. You think I should have joined the plot against Hitler, and got myself hanged like the others.
Bohr
Of course not.
Heisenberg
You don’t say it, because there are some things that can’t be said. But you think it.
Bohr
No.
Heisenberg
What would it have achieved? What would it have achieved if you’d dived in after Christian, and drowned as well? But that’s another thing that can’t be said.
Bohr
Only thought.
Heisenberg
Yes. I’m sorry.
Bohr
And rethought. Every day.
Heisenberg
You had to be held back, I know.
Margrethe
Whereas you held yourself back.
Heisenberg
Better to stay on the boat, though, and fetch it about. Better to remain alive, and throw the lifebuoy. Surely!
Bohr
Perhaps. Perhaps not.
Heisenberg
Better. Better.
Margrethe
Really it is ridiculous. You reasoned your way, both of you, with such astonishing delicacy and precision into the tiny world of the atom. Now it turns out that everything depends upon these really rather large objects on our shoulders. And what’s going on in there is …
Heisenberg
Elsinore.
Margrethe
Elsinore, yes.
Heisenberg
And you may be right. I
was
afraid of what would happen. I
was
conscious of being on the winning side … So many explanations for everything I did! So many of them sitting round the lunch-table! Somewhere at the head of the table, I think, is the real reason I came
to Copenhagen. Again I turn to look .… And for a moment I almost see its face. Then next time I look the chair at the head of the table is completely empty. There’s no reason at all. I didn’t tell Speer simply because I didn’t think of it. I came to Copenhagen simply because I did think of it. A million things we might do or might not do every day. A million decisions that make themselves. Why didn’t you kill me?
Bohr
Why didn’t I …?
Heisenberg
Kill me. Murder me. That evening in 1941. Here we are, walking back towards the house, and you’ve just leapt to the conclusion that I’m going to arm Hitler with nuclear weapons. You’ll surely take any reasonable steps to prevent it happening.
Bohr
By murdering you?
Heisenberg
We’re in the middle of a war. I’m an enemy. There’s nothing odd or immoral about killing enemies.
Bohr
I should fetch out my cap-pistol?
Heisenberg
You won’t need your cap-pistol. You won’t even need a mine. You can do it without any loud bangs, without any blood, without any spectacle of suffering. As cleanly as a bomb-aimer pressing his release three thousand metres above the earth. You simply wait till I’ve gone. Then you sit quietly down in your favourite armchair here and repeat aloud to Margrethe, in front of our unseen audience, what I’ve just told you. I shall be dead almost as soon as poor Casimir. A lot sooner than Gamow.
Bohr
My dear Heisenberg, the suggestion is of course …
Heisenberg
Most interesting. So interesting that it never even occurred to you. Complementarity, once again. I’m your enemy; I’m also your friend. I’m a danger to mankind; I’m also your guest. I’m a particle; I’m also a wave. We have one set of obligations to the world in general, and we have other sets, never to be reconciled, to
our fellow-countrymen, to our neighbours, to our friends, to our family, to our children. We have to go through not two slits at the same time but twenty-two. All we can do is to look afterwards, and see what happened.
Margrethe
I’ll tell you another reason why you did uncertainty: you have a natural affinity for it.
Heisenberg
Well, I must cut a gratifyingly chastened figure when I return in 1947. Crawling on my hands and knees again. My nation back in ruins.
Margrethe
Not really. You’re demonstrating that once more you personally have come out on top.
Heisenberg
Begging for food parcels?
Margrethe
Established in Göttingen under British protection, in charge of post-war German science.
Heisenberg
That first year in Göttingen I slept on straw.
Margrethe
Elisabeth said you had a most charming house thereafter.
Heisenberg
I was given it by the British.
Margrethe
Your new foster-parents. Who’d confiscated it from someone else.
Bohr
Enough, my love, enough.
Margrethe
No, I’ve kept my thoughts to myself for all these years. But it’s maddening to have this clever son forever dancing about in front of our eyes, forever demanding our approval, forever struggling to shock us, forever begging to be told what the limits to his freedom are, if only so that he can go out and transgress them! I’m sorry, but really .… On your hands and knees? It’s my dear, good, kind husband who’s on his hands and knees! Literally. Crawling down to the beach in the darkness in 1943, fleeing like a thief in the night from his own homeland to escape being murdered. The protection of the
German Embassy that you boasted about didn’t last for long. We were incorporated into the Reich.
Heisenberg
I warned you in 1941. You wouldn’t listen. At least Bohr got across to Sweden.
Margrethe
And even as the fishing-boat was taking him across the Sound two freighters were arriving in the harbour to ship the entire Jewish population of Denmark eastwards. That great darkness inside the human soul was flooding out to engulf us all.
Heisenberg
I did try to warn you.
Margrethe
Yes, and where are you? Shut away in a cave like a savage, trying to conjure an evil spirit out of a hole in the ground. That’s what it came down to in the end, all that shining springtime in the 1920s, that’s what it produced—a more efficient machine for killing people.
Bohr
It breaks my heart every time I think of it.
Heisenberg
It broke all our hearts.
Margrethe
And this wonderful machine may yet kill every man, woman, and child in the world. And if we really are the centre of the universe, if we really are all that’s keeping it in being, what will be left?
Bohr
Darkness. Total and final darkness.
Margrethe
Even the questions that haunt us will at last be extinguished. Even the ghosts will die.
Heisenberg
I can only say that I didn’t do it. I didn’t build the bomb.
Margrethe
No, and why didn’t you? I’ll tell you that, too. It’s the simplest reason of all. Because you couldn’t. You didn’t understand the physics.
Heisenberg
That’s what Goudsmit said.
Margrethe
And Goudsmit knew. He was one of your magic circle. He and Uhlenbeck were the ones who did spin.
Heisenberg
All the same, he had no idea of what I did or didn’t understand about a bomb.
Margrethe
He tracked you down across Europe for Allied Intelligence. He interrogated you after you were captured.
Heisenberg
He blamed me, of course. His parents died in Auschwitz. He thought I should have done something to save them. I don’t know what. So many hands stretching up from the darkness for a lifeline, and no lifeline that could ever reach them …
Margrethe
He said you didn’t understand the crucial difference between a reactor and a bomb.
Heisenberg
I understood very clearly. I simply didn’t tell the others.
Margrethe
Ah.
Heisenberg
I understood, though.
Margrethe
But secretly.
Heisenberg
You can check if you don’t believe me.
Margrethe
There’s evidence, for once?
Heisenberg
It was all most carefully recorded.
Margrethe
Witnesses, even?
Heisenberg
Unimpeachable witnesses.
Margrethe
Who wrote it down?
Heisenberg
Who recorded it and transcribed it.
Margrethe
Even though you didn’t tell anyone?
Heisenberg
I told one person. I told Otto Hahn. That terrible night at Farm Hall, after we’d heard the news. Somewhere in the small hours, after everyone had finally gone to bed, and we were alone together. I gave him a reasonably good account of how the bomb had worked.
Margrethe
After the event.
Heisenberg
After the event. Yes. When it didn’t matter any more. All the things Goudsmit said I didn’t understand. Fast neutrons in 235. The plutonium option. A reflective shell to reduce neutron escape. Even the method of triggering it.
Bohr
The critical mass. That was the most important thing. The amount of material you needed to establish the chain-reaction. Did you tell him the critical mass?
Heisenberg
I gave him a figure, yes. You can look it up! Because that was the other secret of the house-party. Diebner asked me when we first arrived if I thought there were hidden microphones. I laughed. I told him the British were far too old-fashioned to know about Gestapo methods. I underestimated them. They had microphones everywhere—they were recording everything. Look it up! Everything we said. Everything we went through that terrible night. Everything I told Hahn alone in the small hours.
Bohr
But the critical mass. You gave him a figure. What was the figure you gave him?
Heisenberg
I forget.
Bohr
Heisenberg …
Heisenberg
It’s all on the record. You can see for yourself.
Bohr
The figure for the Hiroshima bomb …
Heisenberg
Was fifty kilograms.
Bohr
So that was the figure you gave Hahn? Fifty kilograms?
Heisenberg
I said about a ton.
Bohr
About a ton? A thousand kilograms? Heisenberg, I believe I am at last beginning to understand something.