Authors: Michael Frayn
Margrethe
You go on with the reactor, though.
Heisenberg
We go on with the reactor. Of course. Because now there’s no risk of getting it running in time to produce enough plutonium for a bomb. No, we go on with the reactor all right. We work like madmen on the reactor. We have to drag it all the way across Germany, from east to west, from Berlin to Swabia, to get it away from the bombing, to keep it out of the hands of the Russians. Diebner tries to hijack it on the way. We get it away from him, and we set it up in a little village in the Swabian Jura.
Bohr
This is Haigerloch?
Heisenberg
There’s a natural shelter there—the village inn has a wine-cellar cut into the base of a cliff. We dig a hole in the floor for the reactor, and I keep that programme going, I keep it under my control, until the bitter end.
Bohr
But, Heisenberg, with respect now, with the greatest respect, you couldn’t even keep the reactor under your control. That reactor was going to kill you.
Heisenberg
It wasn’t put to the test. It never went critical.
Bohr
Thank God. Hambro and Perrin examined it after the Allied troops took over. They said it had no cadmium control rods. There was nothing to absorb any excess of neutrons, to slow the reaction down when it overheated.
Heisenberg
No rods, no.
Bohr
You believed the reaction would be self-limiting.
Heisenberg
That’s what I originally believed.
Bohr
Heisenberg, the reaction would not have been self-limiting.
Heisenberg
By 1945 I understood that.
Bohr
So if you ever had got it to go critical, it would have melted down, and vanished into the centre of the earth!
Heisenberg
Not at all. We had a lump of cadmium to hand.
Bohr
A
lump
of cadmium? What were you proposing to do with a
lump
of cadmium?
Heisenberg
Throw it into the water.
Bohr
What water?
Heisenberg
The heavy water. The moderator that the uranium was immersed in.
Bohr
My dear good Heisenberg, not to criticise, but you’d all gone mad!
Heisenberg
We were almost there! We had this fantastic neutron growth! We had 670 per cent growth!
Bohr
You’d lost all contact with reality down in that hole!
Heisenberg
Another week. Another fortnight. That’s all we needed!
Bohr
It was only the arrival of the Allies that saved you!
Heisenberg
We’d almost reached the critical mass! A tiny bit bigger and the chain would sustain itself indefinitely. All we need is a little more uranium. I set off with Weizsäcker to try and get our hands on Diebner’s. Another hair-raising journey all the way back across Germany. Constant air raids—no trains—we try bicycles—we never make it! We end up stuck in a little inn somewhere in the middle of nowhere, listening to the thump of bombs falling all round us. And on the radio someone playing the Beethoven G minor cello sonata …
Bohr
And everything was still under your control?
Heisenberg
Under my control—yes! That’s the point! Under my control!
Bohr
Nothing was under anyone’s control by that time!
Heisenberg
Yes, because at last we were free of all constraints! The nearer the end came the faster we could work!
Bohr
You were no longer running that programme, Heisenberg. The programme was running you.
Heisenberg
Two more weeks, two more blocks of uranium, and it would have been German physics that achieved the world’s first self-sustaining chain reaction.
Bohr
Except that Fermi had already done it in Chicago, two years earlier.
Heisenberg
We didn’t know that.
Bohr
You didn’t know anything down in that cave. You were as blind as moles in a hole. Perrin said that there wasn’t even anything to protect you all from the radiation.
Heisenberg
We didn’t have time to think about it.
Bohr
So if it
had
gone critical …
Margrethe
You’d all have died of radiation sickness.
Bohr
My dear Heisenberg! My dear boy!
Heisenberg
Yes, but by then the reactor would have been running.
Bohr
I should have been there to look after you.
Heisenberg
That’s all we could think of at the time. To get the reactor running, to get the reactor running.
Bohr
You always needed me there to slow you down a little. Your own walking lump of cadmium.
Heisenberg
If I had died then, what should I have missed? Thirty years of attempting to explain. Thirty years of reproach and hostility. Even you turned your back on me.
Margrethe
You came to Copenhagen again. You came to Tisvilde.
Heisenberg
It was never the same.
Bohr
No. It was never the same.
Heisenberg
I sometimes think that those final few weeks at Haigerloch were the last happy time in my life. In a strange way it was very peaceful. Suddenly we were out of all the politics of Berlin. Out of the bombing. The war was coming to an end. There was nothing to think about except the reactor. And we didn’t go mad, in fact. We didn’t work all the time. There was a monastery on top of the rock above our cave. I used to retire to the organ-loft in the church, and play Bach fugues.
Margrethe
Look at him. He’s lost. He’s like a lost child. He’s been out in the woods all day, running here, running there. He’s shown off, he’s been brave, he’s been cowardly. He’s done wrong, he’s done right. And now the evening’s come, and all he wants is to go home, and he’s lost.
Heisenberg
Silence.
Bohr
Silence.
Margrethe
Silence.
Heisenberg
And once again the tiller slams over, and Christian is falling.
Bohr
Once again he’s struggling towards the lifebuoy.
Margrethe
Once again I look up from my work, and there’s Niels in the doorway, silently watching me …
Bohr
So, Heisenberg, why did you come to Copenhagen in 1941? It was right that you told us about all the fears you had. But you didn’t really think I’d tell you whether the Americans were working on a bomb.
Heisenberg
No.
Bohr
You didn’t seriously hope that I’d stop them.
Heisenberg
No.
Bohr
You were going back to work on that reactor whatever I said.
Heisenberg
Yes.
Bohr
So, Heisenberg, why did you come?
Heisenberg
Why did I come?
Bohr
Tell us once again. Another draft of the paper. And this time we shall get it right. This time we shall understand.
Margrethe
Maybe you’ll even understand yourself.
Bohr
After all, the workings of the atom were difficult to explain. We made many attempts. Each time we tried they became more obscure. We got there in the end, however. So—another draft, another draft.
Heisenberg
Why did I come? And once again I go through that evening in 1941. I crunch over the familiar gravel, and tug at the familiar bell-pull. What’s in my head? Fear, certainly, and the absurd and horrible importance of someone bearing bad news. But … yes … something else as well. Here it comes again. I can almost see its face. Something good. Something bright and eager
and hopeful.
Bohr
I open the door …
Heisenberg
And there he is. I see his eyes light up at the sight of me.
Bohr
He’s smiling his wary schoolboy smile.
Heisenberg
And I feel a moment of such consolation.
Bohr
A flash of such pure gladness.
Heisenberg
As if I’d come home after a long journey.
Bohr
As if a long-lost child had appeared on the doorstep.
Heisenberg
Suddenly I’m free of all the dark tangled currents in the water.
Bohr
Christian is alive, Harald still unborn.
Heisenberg
The world is at peace again.
Margrethe
Look at them. Father and son still. Just for a moment. Even now we’re all dead.
Bohr
For a moment, yes, it’s the twenties again.
Heisenberg
And we shall speak to each other and understand each other in the way we did before.
Margrethe
And from those two heads the future will emerge. Which cities will be destroyed, and which survive. Who will die, and who will live. Which world will go down to obliteration, and which will triumph.
Bohr
My dear Heisenberg!
Heisenberg
My dear Bohr!
Bohr
Come in, come in …
Act Two
Heisenberg
It was the very beginning of spring. The first time I came to Copenhagen, in 1924. March: raw, blustery northern weather. But every now and then the sun would come out and leave that first marvellous warmth of the year on your skin. That first breath of returning life.
Bohr
You were twenty-two. So I must have been … Thirty-eight.
Bohr
Almost the same age as you were when you came in 1941.
Heisenberg
So what do we do?
Bohr
Put on our boots and rucksacks …
Heisenberg
Take the tram to the end of the line …
Bohr
And start walking!
Heisenberg
Northwards to Elsinore.
Bohr
If you walk you talk.
Heisenberg
Then westwards to Tisvilde.
Bohr
And back by way of Hillerød.
Heisenberg
Walking, talking, for a hundred miles.
Bohr
After which we talked more or less non-stop for the next three years.
Heisenberg
We’d split a bottle of wine over dinner in your flat at the Institute.
Bohr
Then I’d come up to your room …
Heisenberg
That terrible little room in the servants’ quarters in the attic.
Bohr
And we’d talk on into the small hours.
Heisenberg
How, though?
Bohr
How?
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 …