Authors: Michael Frayn
Some physicists now accept that the loss of interference is caused by a much stranger and less quasi-classical aspect of the quantum world—entanglement. The notion was introduced by Schrödinger in 1935, and suggests that where quantum-mechanical entities become involved with each other (as with the particle and the photon), they form states of affairs which continue to have a collective identity and behaviour, even though their components have physically separated again. The difficulties in this are obvious, but there is no interpretation of quantum-mechanical phenomena that does not involve breathtaking challenges to the logic of our everyday experience.
For the references to all these developments see the
bibliography at the end of this Postscript.
*
What about my characters? Are they anything like their originals?
It’s impossible to catch the exact tone of voice of people one never knew, with only the written record to go on, especially when most of what their contemporaries recall them as saying was originally said in other languages. There are also more particular problems with all three of my protagonists.
Bohr, for a start, was as notorious for his inarticulacy and inaudibility as he was famous for his goodness and lovability. He was fluent in various languages, but I have heard it said that the problem was to know which language he was being fluent in. Schrödinger, after his epic confrontation with Bohr in 1926, described him as often talking ‘for minutes almost in a dreamlike, visionary and really quite unclear manner, partly because he is so full of consideration and constantly hesitates—fearing that the other might take a statement of his [Bohr’s] point of view as an insufficient appreciation of the other’s …’ My Bohr is necessarily a little more coherent than this—and I have been told by various correspondents who knew him that in private, if not in public, he could be much more cogent and incisive than Schrödinger evidently found him.
The problem with Margrethe is that there is relatively little biographical material to go on. She and Niels were plainly mutually devoted, and everything suggests that she was as generally loved as he was. She had no scientific training, but Bohr constantly discussed his work with her, presumably avoiding technical language—though she must have become fairly familiar with even that since she typed out each draft of his papers. I suspect she was more gracious and reserved than she appears here, but she plainly had great firmness of character—in later life she was known as
Dronning
(Queen) Margrethe. She was always cooler about Heisenberg than Bohr was, and she was openly angry about
his visit in 1941. According to Bohr she objected strongly to his being invited to the house, and relented only when Bohr promised to avoid politics and restrict the conversation to physics. Bohr himself always refused to be drawn about Heisenberg’s trip in 1941, but she insisted, even after the war, even after all Heisenberg’s attempts to explain, ‘No matter what anyone says, that was a hostile visit.’
The problem with Heisenberg is his elusiveness and ambiguity, which is of course what the play is attempting to elucidate. The one thing about him that everyone agreed upon was what Max Born, his mentor in Göttingen, called ‘his unbelievable quickness and precision of understanding.’ The contrast with Bohr is almost comic. ‘Probably [Bohr’s] most characteristic property,’ according to George Gamow, ‘was the slowness of his thinking and comprehension.’
As a young man Heisenberg seems to have had an appealing eagerness and directness. Born described him as looking like a simple farm boy, with clear bright eyes, and a radiant expression on his face. Somebody else thought he looked ‘like a bright carpenter’s apprentice just returned from technical school.’ Victor Weisskopf says that he made friends easily, and that everyone liked him. Bohr, after their first meeting in 1922, was delighted by Heisenberg’s ‘nice shy nature, his good temper, his eagerness and his enthusiasm.’ There was something about him of the prize-winning student, who is good at everything required of him, and Bohr was not the only father-figure to whom he appealed. He had a somewhat similar relationship to Sommerfeld, his first professor in Munich, and in his difficulties with the Nazis he turned to two elders of German physics for counsel, Max Planck and Max von Laue. His closest friend and colleague was probably Carl Friedrich von Weizsäcker, who was younger than him, but it is striking that during his internment the person he chose to confide his explanation of the Hiroshima bomb to was not Weizsäcker, who was interned with him (although he may well have discussed it with him already), but the 66-year-old Otto Hahn.
The American physicist Jeremy Bernstein says that ‘he
had the first truly quantum-mechanical mind—the ability to take the leap beyond the classical visualizing pictures into the abstract, all-but-impossible-to-vizualise world of the subatomic …’ Cassidy believes that a great part of his genius was his ‘ability to adopt a serviceable solution regardless of accepted wisdom.’ Rudolf Peierls stresses his intuition. He would ‘almost always intuitively know the answer to a problem, then look for a mathematical solution to give it to him.’ The obverse of this, according to Peierls, is that ‘he was always very casual about numbers’—a weakness that seems to have contributed to his downfall—or his salvation—in the atomic bomb programme.
Margrethe always found him difficult, closed, and oversensitive, and this propensity to be withdrawn and inturned was exacerbated as life went on—first by his political problems in the thirties, and then by his efforts to reconcile the moral irreconcilables of his wartime work. His autobiographical writing is rather stiff and formal, and his letters to Bohr, even during the twenties and thirties, are correct rather than intimate. Throughout the period of their closest friendship they addressed each other with the formal
Sie
, and switched to
du
only when Heisenberg also had a chair.
The conversations that Heisenberg claimed such freedom to recreate in his memoirs are stately. Much more plausibly colloquial is the transcript of David living’s long interview with him for
The Virus House
, living’s history of the German bomb programme, though he is still (naturally) watchful. In the transcripts of the relatively unguarded conversations that the German atomic team had among themselves during their internment, where Heisenberg emerges as the dominant figure, both morally and practically, a certain hard-headed worldliness can be detected. He is much concerned with professional prospects, and with how they might make some money out of their wartime researches. When one of the others says that if they agree to work on atomic matters under Allied control they will be looked down upon as traitors ‘in the eyes of the masses’, Heisenberg replies: ‘No. One must do that cleverly. As far as the masses are
concerned it will look as though we unfortunately have to continue our scientific work under the wicked Anglo-Saxon control, and that we can do nothing about it. We will have to appear to accept this control with fury and gnashing of teeth.’
There was always something a little sharp and harsh about him, something that at its best inspired respect rather than love, and that after the war occasioned really quite astonishing hostility and contempt. Even Samuel Goudsmit turned against him. Goudsmit was an old friend and colleague; when the investigators of the Alsos mission, the Allied agency for gathering intelligence on German atomic research, for which he was working, finally broke into Heisenberg’s office in 1945, one of the first things they saw was a picture of the two of them together that Heisenberg had kept there as a memento of happier days. But when Goudsmit subsequently interrogated Heisenberg he found him arrogant and self-involved. Goudsmit had understandably bitter feelings at the time—he had just discovered the record of his parents’ death in Auschwitz. Heisenberg was also caught in a false position. Confident that his team had been far ahead of the Americans, he offered Goudsmit his services in initiating them into the secrets of uranium fission. (Goudsmit did nothing to correct his misapprehension, which gave Heisenberg, when the truth finally came out, grounds for returning Goudsmit’s bitterness.) In his superficial and strangely unimpressive book on Alsos, Goudsmit wrote about Heisenberg and his team with contemptuous dismissal, and in the year-long correspondence in the American press that followed its publication, accused him of self-importance and dishonesty.
Weisskopf gave a reception for Heisenberg during his trip to America in 1949, but about half the guests—including many people from the Los Alamos team—failed to appear, explaining to Weisskopf that they didn’t want to shake the hand of the man who had tried to build a bomb for Hitler. Even Cassidy, who gives full measure to Heisenberg as a physicist in his biography, is notably cool and cautious in his assessment of Heisenberg’s role in the German bomb
programme. Ronald Fraser, the British intelligence officer who escorted Heisenberg back to Copenhagen in 1947 (the British seem to have been frightened that he would defect to the Russians, or be kidnapped by them) replied to living’s inquiry about the trip in tones of patronising contempt that seem slightly unhinged. The whole story of “a kind of confrontation”,’ he wrote to Irving, ‘in the matter of his 1941 natter with Bohr in the Tivoli Gardens [sic] is a typical Heisenberg fabrication—maybe a bit brighter than a thousand others, but like them all a product of his
Blut und Boden
guilt complex, which he rationalises that quickly that the stories become
for him
the truth, the whole truth, and nothing but the truth. Pitiful, in a man of his mental stature.’
The historian Paul Lawrence Rose, who has focussed upon Heisenberg as an emblem for what he regards as the general failings of German culture, also takes a remarkably high moral tone. In a paper he wrote in 1984, entitled
Heisenberg, German Morality and the Atomic Bomb
, he talked about Heisenberg’s ‘guff,’ his ‘self-serving, self-deluding claims,’ and his ‘elementary moral stupidity.’ After a further fourteen years research Professor Rose returned to the subject in 1998 in a full-length book which was published after the play was produced, and which has attracted considerable attention,
Heisenberg and the Nazi Atomic Bomb Project: a Study in German Culture
. His contempt for Heisenberg remains unmoderated. He believes that Heisenberg failed, in spite of his perfect readiness to serve the Nazi regime, because of his arrogance and wrong-headedness, and because he embodied various vices of German culture in general, and of the Nazi regime in particular, whose values he had absorbed.
It is a difficult book to read—Rose can scarcely quote a word of Heisenberg’s without adding his own disparaging qualification. Here is a selection of his interjections on two facing pages taken more or less at random: ‘ … self-incriminating … a somewhat inadequate explanation … this inconsistency … the falseness of these lame excuses … a characteristic Heisenberg lie … Heisenberg’s usual facile rationalising ability … Heisenberg then went on glibly to
recollect … the delusory nature of Heisenberg’s memory …’
You wonder at times whether it wouldn’t look better if it was handwritten in green ink, with no paragraph breaks. Rose seems to be aware himself of the effect he is producing. He realises, he says, that some readers may ‘find distasteful the recurrent moral judgments passed on Heisenberg.’ They may also, he thinks, be put off by what seems a ‘lack of sympathy with German culture’—he cannot say, he confesses, that his ‘British background’ has made him entirely sympathetic to it. He is at pains to distance himself from any unfortunate echoes that this attitude may awaken: he hopes that readers will not accuse him of ‘unthinkingly preaching a crude view of German “national character,” whatever that term may mean.’ What he is concerned with, he explains, is not that at all, but ‘the enduring nature of what one might call the “deep culture” of Germany … In this book I have tried to penetrate into how Germans think—or rather, perhaps, used to think—and to show how radically different are German and what I have termed “Western” mentalities and sensibilities.’ It is this that underlies what he calls, without apparent irony, ‘the Heisenberg problem.’
Some of his evidence induces a certain dizziness. He quotes without comment, as the epigraph to a chapter, a remark by Albert Speer, the Nazi Minister of Armaments: ‘I do hope Heisenberg is not now claiming that they tried, for reasons of principle, to sabotage the project by asking for such minimal support!’ It’s true that any claim to have sabotaged the project, particularly for reasons of principle, would represent an astonishing departure from Heisenberg’s habitual caution on the subject. But the question is not what Speer hoped, but whether Heisenberg
did
make such a claim.
So did he or didn’t he? Rose doesn’t tell us, and the only reference he gives is Gitta Sereny’s new book,
Albert Speer: His Battle with Truth
. The allusion is to the crucial meeting at Harnack House in 1942, mentioned in the play. Speer said in his memoirs that he was ‘rather put out’ by the very small amount of money that Heisenberg requested to run the nuclear research programme. In an earlier draft of the
manuscript (the ‘Spandau draft’), says Sereny, he had added in brackets the remark that Rose quotes—and Heisenberg, she says, ‘did in fact try precisely that after the war.’
So he
did
make the claim! But when and where? Sereny doesn’t tell us. The only references to the smallness of the sums of money he asked for that I can find in the record are the one quoted, by Speer himself, and another by Field Marshal Milch, Goering’s deputy in the Luftwaffe, who was also present at the meeting. There’s certainly nothing about it in Heisenberg’s memoirs, or in Robert Jungk’s book,
Brighter Than a Thousand Suns
, or in Heisenberg’s long interview with Irving, or in the other two obvious places, his interview with
Der Spiegel
in 1967, when living’s book was published, or his review of the book in the
Frankfurter Allgemeine Zeitung
. I hardly like to put myself forward to fill the gap, but so far as I know the only reference he made to the subject was posthumously and fictitiously in my play.