《哥本哈根》是迈克尔·弗雷恩创作的戏剧，基于1941年在哥本哈根发生的一次事件——物理学家尼尔斯·玻尔和他的学生维尔纳·海森堡之间的会面。该剧于1998年在伦敦国家剧院首演，并上演了超过300场

版权归属为迈克尔·弗雷恩，如有侵权，联系作者处理

特别说明：此本涉及很多专业名词，谨慎盲走。

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 Hillered.

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. . .

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: Mostly Germans.

Bohr: Yes, but Schr?dinger in Zurich, Fermi in Rome.

Heisenberg: Chadwick and Dirac in England.

Bohr: Joliot and de Broglie in Paris.

Heisenberg: Gamow and Landers 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 Born at G?ttingen, 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 become your assistant.

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. You said you couldn' t think in Copenhagen.

Heisenberg: No, well, it was summer by then. I had my hay fever.

Margrethe: On Heligoland, on your own, on a rocky bare island in the middle of the North Sea. . .

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 no one did. it was a very obscure backwater of arithmetic . . . 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 Schr?dinger nonsense?

Bohr: Nonsense? Come, come. Schr?dinger'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 Schr?dinger'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. Schr?dinger 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 Schr?dinger 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!

Bohr: Nor will he!

Heisenberg: You made him ill! He had to retire to bed to get away from you!

Bohr: He had a slight feverish cold.

Heisenberg: Margrethe had to nurse him!

Margrethe: I dosed him with tea and cake to keep his strength up.

Heisenberg: Yes, while you pursued him even into the sickroom! Sat on his bed and hammered away at him!

Bohr: Perfectly politely.

Heisenberg: You were the Pope and the Holy Office and the Inquisition all rolled into one! And then, and then, after Schr?dinger had fled back to Zurich and this I will never forget, Bohr, this I will never let you forget you started to take his side! You turned on me!

Bohr: Because you'd gone mad by this time! You'd become fanatical! You were refusing to allow wave theory any place in quantum mechanics at all!

Heisenberg: You'd completely turned your coat!

Bohr: I said wave mechanics and matrix mechanics were simply alternative tools.

Heisenberg: Something you're always accusing me of. 'If it works it works.' Never mind what it means.

Bohr: Of course I mind what it means.

Heisenberg: What it means in language.

Bohr: In plain language, yes.

Heisenberg: What something means is what it means in mathematics.

Bohr: You think that so long as the mathematics works out, the sense doesn't matter.

Heisenberg: Mathematics is sense! That's what sense is!

Bohr: But in the end, in the end, remember, we have to be able to explain it all to Margrethe!

Margrethe: Explain it to me? You couldn't even explain it to each other! You went on arguing into the small hours every night! You both got so angry!

Bohr: We also both got completely exhausted.

Margrethe: It was the cloud chamber that finished you.

Bohr: Yes, because if you detach an electron from an atom, and send it through a cloud chamber, you can see the track it leaves.

Heisenberg: And it's a scandal. There shouldn't be a track!

Margrethe: According to your quantum mechanics.

Heisenberg: There isn't a track! No orbits! No tracks or trajectories! Only external effects!

Margrethe: Only there the track is. I've seen it myself, as clear as the wake left by a passing ship.

Bohr: It was a fascinating paradox.

Heisenberg: You actually loved the paradoxes, that's your problem. You revelled in the contradictions.

Bohr: Yes, and you've never been able to understand the suggestiveness of paradox and contradiction. That's your problem. You live and breathe paradox and contradiction, but you can no more see the beauty of them than the fish can see the beauty of the water.

Heisenberg: I sometimes felt as if I was trapped in a kind of windowless hell. You don't realise how aggressive you are. Prowling up and down the room as if you're going to eat someone - and I can guess who it's going to be.

Bohr: That's the way we did the physics, though.

Margrethe: No. No! In the end you did it on your own again! Even you! You went off ski-ing in Norway.

Bohr: I had to get away from it all!

Margrethe: And you worked out complementarity in Norway, on your own.

Heisenberg: The speed he skis at he had to do something to keep the blood going round. It was either physics or frostbite.

Bohr: Yes, and you stayed behind in Copenhagen. . .

Heisenberg: And started to think at last.

Margrethe: You're a lot better off apart, you two.

Heisenberg: Having him out of town was as liberating as getting away from my hay fever on Heligoland.

Margrethe: I shouldn't let you sit anywhere near each other, if I were the teacher.

Heisenberg: And that's when I did uncertainty. Walking round Faelled Park on my own one horrible raw February night. It's very late, and as soon as I've turned off into the park I'm completely alone in the darkness. I start to think about what you'd see, if you could train a telescope on me from the mountains of Norway. You'd see me by the street lamps on the Blegdamsvej, then nothing as I vanished into the darkness, then another glimpse of me as I passed the lamp-post in front of the bandstand. And that's what we see in the cloud chamber. Not a continuous track but a series of glimpses a series of collisions between the passing electron and various atoms of water vapour. . . . Or think of you, on your great papal progress to Leiden in 1925. What did Margrethe see of that, at home here in Copenhagen? A picture postcard from Hamburg, perhaps. Then one from Leiden. One from Gottingen. One from Berlin. Because what we see in the cloud chamber are not even the collisions themselves, but the water droplets that condense around them, as big as cities around a traveller no, vastly bigger still, relatively complete countries - Germany. . . Holland. . . Germany again. There is no track, there are no precise addresses; only a vague list of countries visited. I don't know why we hadn't thought of it before, except that we were too busy arguing to think at all.

Bohr: You seem to have given up on all forms of discussion. By the time I get back from Norway I find you've done a draft of your uncertainty paper and you've already sent it for publication!

Margrethe: And an even worse battle begins.

Bohr: My dear good Heisenberg, it's not open behaviour to rush a first draft into print before we've discussed it together! It's not the way we work!

Heisenberg: No, the way we work is that you hound me from first thing in the morning till last thing at night! The way we work is that you drive me mad!

Bohr: Yes, because the paper contains a fundamental error.

Margrethe: And here we go again.

Heisenberg: No, but I show him the strangest truth about the universe that any of us has stumbled on since relativity that you can never know everything about the whereabouts of a particle, or anything else, even Bohr now, as he prowls up and down the room in that maddening way of his, because we can't observe it without introducing some new element into the situation, an atom of water vapour for it to hit, or a piece of light things which have an energy of their own, and which therefore have an effect on what they hit. A small one, admittedly, in the case of Bohr . . .

Bohr: Yes, if you know where I am with the kind of accuracy we're talking about when we're dealing with particles, you can still measure my velocity to within - what . . . ?

Heisenberg: Something like a billionth of a billionth of a kilometre per second. The theoretical point remains, though, that you have no absolutely determinate situation in the world, which among other things lays waste to the idea of causality, the whole foundation of science because if you don't know how things are today you certainly can't know how they're going to be tomorrow. I shatter the objective universe around you and all you can say is that there's an error in the formulation!

Bohr: There is!

Margrethe: Tea, anyone? Cake?

Heisenberg: Listen, in my paper what we're trying to locate is not a free electron off on its travels through a cloud chamber, but an electron when it's at home, moving around inside an atom. . .

Bohr: And the uncertainty arises not, as you claim, through its indeterminate recoil when it's hit by an incoming photon. . .

Heisenberg: Plain language, plain language!

Bohr: This is plain language.

Heisenberg: Listen. . .

Bohr: The language of classical mechanics.

Heisenberg: Listen! Copenhagen is an atom. Margrethe is its nucleus. About right, the scale? Ten thousand to one?

Bohr: Yes, yes.

Heisenberg: Now, Bohr's an electron. He's wandering about the city somewhere in the darkness, no one knows where. He's here, he's there, he's everywhere and nowhere. Up in Faelled Park, down at Carlsberg. Passing City Hall, out by the harbour. I'm a photon. A quantum of light. I'm despatched into the darkness to find Bohr. And I succeed, because I manage to collide with him. . . . But what's happened? Look - he's been slowed down, he's been deflected! He's no longer doing exactly what he was so maddeningly doing when I walked into him!

Bohr: But, Heisenberg, Heisenberg! You also have been deflected! If people can see what's happened to you, to their piece of light, then they can work out what must have happened to me! The trouble is knowing what's happened to you! Because to understand how people see you we have to treat you not just as a particle, but as a wave. I have to use not only your particle mechanics, I have to use the Schr?dinger wave function.

Heisenberg: I know - I put it in a postscript to my paper.

Bohr: Everyone remembers the paper - no one remembers the postscript. But the question is fundamental. Particles are things, complete in themselves. Waves are disturbances in something else.

Heisenberg: I know. Complementarity. It's in the postscript.

Bohr: They're either one thing or the other. They can't be both. We have to choose one way of seeing them or the other. But as soon as we do we can't know everything about them.

Heisenberg: And off he goes into orbit again. Incidentally exemplifying another application of complementarity. Exactly where you go as you ramble around is of course completely determined by your genes and the various physical forces acting on you. But it's also completely determined by your own entirely inscrutable whims from one moment to the next. So we can't completely understand your behaviour without seeing it both ways at once, and that's impossible. Which means that your extraordinary peregrinations are not fully objective aspects of the universe. They exist only partially, through the efforts of me or Margrethe, as our minds shift endlessly back and forth between the two approaches.

Bohr: You've never absolutely and totally accepted complementarity, have you?

Heisenberg: Yes! Absolutely and totally! I defended it at the Como Conference in 1927! I have adhered to it ever afterwards with religious fervour! You convinced me. I humbly accepted your criticisms.

Bohr: Not before you'd said some deeply wounding things.

Heisenberg: Good God, at one point you literally reduced me to tears!

Bohr: Forgive me, but I diagnosed them as tears of frustration and rage.

Heisenberg: I was having a tantrum?

Bohr: I have brought up children of my own.

Heisenberg: And what about Margrethe? Was she having a tantrum? Klein told me you reduced her to tears after I'd gone, making her type out your endless redraftings of the complementarity paper.

Bohr: I don't recall that.

Margrethe: I do.

Heisenberg: We had to drag Pauli out of bed in Hamburg once again to come to Copenhagen and negotiate peace.

Bohr: He succeeded. We ended up with a treaty. Uncertainty and complementarity became the two central tenets of the Copenhagen Interpretation of Quantum Mechanics.

Heisenberg: A political compromise, of course, like most treaties.

Bohr: You see? Somewhere inside you there are still secret reservations.

Heisenberg: Not at all - it works. That's what matters. It works, it works, it works!

Bohr: It works, yes. But it's more important than that. Because you see what we did in those three years, Heisenberg? Not to exaggerate, but we turned the world inside out! Yes, listen, now it comes, now it comes. . . . We put man back at the centre of the universe. Throughout history we keep finding ourselves displaced. We keep exiling ourselves to the periphery of things. First we turn ourselves into a mere adjunct of God's unknowable purposes, tiny figures kneeling in the great cathedral of creation. And no sooner have we recovered ourselves in the Renaissance, no sooner has man become, as Protagoras proclaimed him, the measure of all things, than we're pushed aside again by the products of our own reasoning! We're dwarfed again as physicists build the great new cathedrals for us to wonder at - the laws of classical mechanics that predate us from the beginning of eternity, that will survive us to eternity's end, that exist whether we exist or not. Until we come to the beginning of the twentieth century, and we're suddenly forced to rise from our knees again.

Heisenberg: It starts with Einstein.

Bohr: It starts with Einstein. He shows that measurement.....measurement, on which the whole possibility of science depends measurement is not an impersonal event that occurs with impartial universality. It's a human act, carried out from a specific point of view in time and space, from the one particular viewpoint of a possible observer. Then, here in Copenhagen in those three years in the mid twenties we discover that there is no precisely determinable objective universe. That the universe exists only as a series of approximations. Only within the limits determined by our relationship with it. Only through the understanding lodged inside the human head.

Margrethe: So this man you've put at the centre of the universe - is it you, or is it Heisenberg?

Bohr: Now, now, my love.

Margrethe: Yes, but it makes a difference.

Bohr: Either of us. Both of us. Yourself. All of us.

Margrethe: If it's Heisenberg at the centre of the universe, then the one bit of the universe that he can't see is Heisenberg.

Heisenberg: So. . .

Margrethe: So it's no good asking him why he came to Copenhagen in 1941. He doesn't know!

Heisenberg: I thought for a moment just then I caught a glimpse of it.

Margrethe: Then you turned to look.

Heisenberg: And away it went.

Margrethe: Complementarity again. Yes?

Bohr: Yes, yes.

Margrethe: I've typed it out often enough. If you're doing something you have to concentrate on you can't also be thinking about doing it, and if you're thinking about doing it then you can't actually be doing it. Yes?

Heisenberg: Swerve left, swerve right, or think about it and die.

Bohr: But after you've done it. . .

Margrethe: You look back and make a guess, just like the rest of us. Only a worse guess, because you didn't see yourself doing it, and we did. Forgive me, but you don't even know why you did uncertainty in the first place.

Bohr: Whereas if you're the one at the centre of the universe . . .

Margrethe: Then I can tell you that it was because you wanted to drop a bomb on Schr?dinger.

Heisenberg: I wanted to show he was wrong, certainly.

Margrethe: And Schr?dinger was winning the war. When the Leipzig chair first became vacant that autumn he was short-listed for it and you weren't. You needed a wonderful new weapon.

Bohr: Not to criticise, Margrethe, but you have a tendency to make everything personal.

Margrethe: Because everything is personal! You've just read us all a lecture about it! You know how much Heisenberg wanted a chair. You know the pressure he was under from his family. I'm sorry, but you want to make everything seem heroically abstract and logical. And when you tell the story, yes, it all falls into place, it all has a beginning and a middle and an end. But I was there, and when I remember what it was like I'm there still, and I look around me and what I see isn't a story! It's confusion and rage and jealousy and tears and no one knowing what things mean or which way they're going to go.

Heisenberg: All the same, it works, it works.

Margrethe: Yes, it works wonderfully. Within three months of publishing your uncertainty paper you're offered Leipzig.

Heisenberg: I didn't mean that.

Margrethe: Not to mention somewhere else and somewhere else.

Heisenberg: Halle and Munich and Zürich.

Bohr: And various American universities.

Heisenberg: But I didn't mean that.

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 re-establish 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 ski-ing 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.

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 have to say – if people are to be measured strictly in terms of observable quantities...

Heisenberg: Then we should need a strange new quantum ethics. There’d be a place in heaven for me. And another one for the SS man I met on my way home from Haigerloch. That was the end of my war. The Allied troops were closing in; there was nothing more we could do. Elisabeth and the children had taken refuge in a village in Bavaria, so I went to see them before I was captured. I had to go by bicycle – there were no trains or road transport by that time – and I had to travel by night and sleep under a hedge by day, because all through the daylight hours the skies were full of Allied planes, scouring the roads for anything that moved. A man on a bicycle would have been the biggest target left in Germany. Three days and three nights I travelled. Out of Württemberg, down through the Swabian Jura and the first foothills of the Alps. Across my ruined homeland. Was this what I’d chosen for it? This endless rubble? This perpetual smoke in the sky? These hungry faces? Was this my doing? And all the desperate people on the roads. The most desperate of all were the SS. Bands of fanatics with nothing left to lose, roaming around shooting deserters out of hand, hanging them from roadside trees. The second night, and suddenly there it is – the terrible familiar black tunic emerging from the twilight in front of me. On his lips as I stop – the one terrible familiar word. ’Deserter,’ he says. He sounds as exhausted as I am. I give him the travel order I’ve written for myself. But there’s hardly enough light in the sky to read by, and he’s too weary to bother. He begins to open his holster instead. He’s going to shoot me because it’s simply less labour. And suddenly I’m thinking very quickly and clearly – it’s like ski-ing, or that night on Heligoland, or the one in Faelled Park. What comes into my mind this time is the pack of American cigarettes I’ve got in my pocket. And already it’s in my hand – I’m holding it out to him. The most desperate solution to a problem yet. I wait while he stands there looking at it, trying to make it out, trying to think – his left hand holding my useless piece of paper, his right on the fastening of the holster. There are two simple words in large print on the pack: Lucky Strike. He closes the holster, and takes the cigarettes instead... It had worked, it had worked! Like all the other solutions to all the other problems. For twenty cigarettes he let me live. And on I went. Three days and three nights. Past the weeping children, the lost and hungry children, drafted to fight, then abandoned by their commanders. Past the starving slave-labourers walking home to France, to Poland, to Estonia. Through Gammertingen and Biberach and Memmingen. Mindelheim, Kaufbeuren, and Sch?ngau. Across my beloved homeland. My ruined and dishonoured and beloved homeland.

Bohr: My dear Heisenberg! My dear friend!

Margrethe: Silence. The silence we always in the end return to.

Heisenberg: And of course I know what they’re thinking about.

Margrethe: All those lost children on the road.

Bohr: Heisenberg wandering the world like a lost child himself.

Margrethe: Our own lost children.

Heisenberg: And over goes the tiller once again.

Bohr: So near, so near! So slight a thing!

Margrethe: He stands in the doorway, watching me, then he turns his head away...

Heisenberg: And once again away he goes, into the dark waters.

Bohr: Before we can lay our hands on anything, our life’s over.

Heisenberg: Before we can glimpse who or what we are, we’re gone and laid to dust.

Bohr: Settled among all the dust we raised.

Margrethe: And sooner or later there will come a time when all our children are laid to dust, and all our children’s children.

Bohr: When no more decisions, great or small, are ever made again. When there’s no more uncertainty, because there’s no more knowledge.

Margrethe: And when all our eyes are closed, when even the ghosts have gone, what will be left of our beloved world? Our ruined and dishonoured and beloved world?

Heisenberg: But in the meanwhile, in this most precious meanwhile, there it is. The trees in Faelled Park. Gammertingen and Biberach and Mindelheim. Our children and our children’s children. Preserved, just possibly, by that one short moment in Copenhagen. By some event that will never quite be located or defined. By that final core of uncertainty at the heart of things.

ACT TWO 完结