On 25 May 2011, the President of the United States, Barack Obama, speaking to the parliament of the United Kingdom, singled out Newton, Darwin, and Alan Turing as British contributors to science. Celebrity is an imperfect measure of significance, and politicians do not confer scientific status, but Obama’s choice signalled that public recognition of Alan Turing had attained a level very much higher than in 1983, when this book first appeared.
Born in London on 23 June 1912, Alan Turing might just have lived to hear these words, had he not taken his own life on 7 June 1954. In that very different world, his name had gone unmentioned in its legislative forums. Yet in the secret world, over which Eisenhower and Churchill still reigned, and in which the newly reorganised NSA and GCHQ were the holy of holies, their names to be whispered, Alan Turing had a unique place. He had been the chief backroom boy when American power overtook British in 1942, with a scientific role whose climax came on 6 June 1944, just ten years before that early death.
Alan Turing played a central part in world history. Yet it would be misleading to portray his drama as a power play, or as framed by the conventional political issues of the twentieth century. He was not political as defined by contemporary intellectuals, revolving as they did around alignment or non-alignment with the Communist party. Some of his friends and colleagues were indeed party members, but that was not his issue. (Incidentally, it is equally hard to find money-motivated ‘free enterprise’, idolised since the 1980s, playing any role in his story.) Rather, it was his individual freedom of mind, including his sexuality, which mattered − a question taken much more seriously in the post-1968 and even more in the post-1989 era. But beyond this, the global impact of pure science rises above all national boundaries, and the sheer timelessness of pure mathematics transcends the limitations of his twentieth-century span. When Turing returned to the prime numbers in 1950 they were unchanged from when he left them in 1939, wars and superpowers notwithstanding. As G. H. Hardy famously said, they are so. This is mathematical culture, and such was his life, presenting a real difficulty to minds set in literary, artistic or political templates.
Yet it is not easy to separate transcendence from emergency: it is striking how leading scientific intellects were recruited to meet the existential threat Britain faced in 1939. The struggle with Nazi Germany called not just for scientific knowledge but the cutting edge of abstract thought, and so Turing’s quiet logical preparations in 1936-8 for the war of codes and ciphers made him the most effective anti-Fascist amongst his many anti-Fascist contemporaries. The historical parallel with physics, with Turing as a figure roughly analogous to Robert Oppenheimer, is striking. This legacy of 1939 is still unresolved, in the way that secret state purposes are seamlessly woven into intellectual and scientific establishments today, a fact that is seldom remarked upon.
The same timelessness lies behind the central element of Alan Turing’s story: the universal machine of 1936, which became the general-purpose digital computer in 1945. The universal machine is the focal, revolutionary idea of Turing’s life, but it did not stand alone; it flowed from his having given a new and precise formulation of the old concept of algorithm, or mechanical process. He could then say with confidence that all algorithms, all possible mechanical processes, could be implemented on a universal machine. His formulation became known immediately as ‘the Turing machine’ but now it is impossible not to see Turing machines as computer programs, or software.
Nowadays it is perhaps taken rather for granted that computers can replace other machines, whether for record-keeping, photography, graphic design, printing, mail, telephony, or music, by virtue of appropriate software being written and executed. No-one seems surprised that industrialised China can use just the same computers as does America. Yet that such universality is possible is far from obvious, and it was obvious to no-one in the 1930s. That the technology is digital is not enough: to be all-purpose computers must allow for the storage and decoding of a program. That needs a certain irreducible degree of logical complexity, which can only be made to be of practical value if implemented in very fast and reliable electronics. That logic, first worked out by Alan Turing in 1936, then implemented electronically in the 1940s, and nowadays embodied in microchips, is the mathematical idea of the universal machine.
In the 1930s only a very small club of mathematical logicians could appreciate Turing’s ideas. But amongst these, only Turing himself had the practical urge as well, capable of turning his hand from the 1936 purity of definition to the software engineering of 1946: ‘every known process has got to be translated into instruction table form …’ (p. 326). One of Turing’s 1946 colleagues, Donald Davies, later developed such instruction tables (as Turing called programs) for ‘packet switching’ and these grew into the Internet protocols. Giants of the computer industry did not see the Internet coming, but they were saved by Turing’s universality: the computers of the 1980s did not need to be re-invented to handle these new tasks. They needed new software and peripheral devices, they needed greater speed and storage, but the fundamental principle remained. That principle might be decribed as the law of information technology: all mechanical processes, however ridiculous, evil, petty, wasteful, or pointless, can be put on a computer. As such, it goes back to Alan Turing in 1936.
That Alan Turing’s name has not from the start been consistently associated with praise or blame for this technological revolution is due partly to his lack of effective publication in the 1940s. Science absorbs and overtakes individuals, especially in mathematics, and Alan Turing swam in this anonymising culture, never trying to make his name, although frustrated at not being taken seriously. In fact, his competitive spirit went instead into marathon running at near-Olympic level. He omitted to write that monograph on ‘the theory and practice of computing’ which would have stamped his name on the emergent post-war computer world. In 2000 the leading mathematical logician Martin Davis, whose work since 1949 had greatly developed Turing’s theory of computability, published a book1 which was in essence just what Turing could have written in 1948, explaining the origin of the universal machine of 1936, showing how it became the stored-program computer of 1945, and making it clear that John von Neumann must have learnt from Turing’s 1936 work in formulating his better-known plan. Turing’s very last publication, the Science News article of 1954 on computability, demonstrates how ably he could have written such an analysis. But even there, on terrain that was incontestably his own discovery, he omitted to mention his own leading part.
Online search engines, which work with such astonishing speed and power, are algorithms, and so equivalent to Turing machines. They are are also descendants of the particular algorithms, using sophisticated logic, statistics and parallel processing, that Turing expertly pioneered for Enigma-breaking. These were search engines for the keys to the Reich. But he asked for, and received, very little public credit for what has subsequently proved an all-conquering discovery: that all algorithms can be programmed systematically, and implemented on a universal machine. Instead, he nailed his colours to the mast of what he called ‘intelligent machinery’, but which came to be called Artificial Intelligence after 1956. This far more ambitious and contentious research programme has not developed as Turing hoped, at least as yet. Why did Turing go so public on AI, and make so little of himself as an established maestro of algorithms and the founder of programming? Partly, because AI was for him the really fundamental scientific question. The puzzle of mind and matter was the question which drove him most deeply. But to some extent he must have been a victim of his own suppressed success. The fact that he knew so much of the algorithms of the secret war, and that the war had made the vital link between logic and electronics, cramped his style and constrained his communication. In his 1946 report his guarded allusion to the importance of cryptographic algorithms (p. 332) reflects an inhibition that must have infected all that came later.
Only after thirty years did the scale and depth of wartime cryptanalysis at Bletchley Park begin to leak out, allowing a serious assessment of Alan Turing’s life to be attempted. This point coincided with the break-out of cryptology theory into an expanding computer science, with a re-assessment of the Second World War in general, and with the impact of 1970s sexual liberation. The 1968 social revolution, which Turing anticipated, had to happen before his story could be liberated. (Even so, the change in UK vetting and military law came only in the 1990s, and a legal principle of equality was not established until 2000. ‘Don’t ask don’t tell’ ended only while I was writing this Preface in 2011, showing how the issues of chapter 8 have remained literally unspeakable in the US military.) Alan Turing’s story shows the first elements of this liberating process in the Norway of 1952, since the men-only dances he heard about (p. 476) were probably organised by the fledgling Scandinavian gay organisation. In addition to the gay-themed novels mentioned on p. 487, Norman Routledge recalled in 1992 how Turing expected him to read André Gide in French. One regret, voiced in note 8.31, is that his letters to Lyn Newman did not survive (they were destroyed by John Turing). Their content can be guessed from what in 1957 she wrote to a friend: ‘Dear Alan, I remember his saying to me so simply & sadly “I just can’t believe it’s as nice to go to bed with a girl as with a boy” and all I could say was “I entirely agree with you − I also much prefer boys.”’ This interchange, then confined to a discreet privileged circle, could now be a TV chat show joke, with a happy resonance of the repartee of his famous imitation game. But Alan Turing’s simple openness came decades too early.
It is not difficult to imagine the hostility and stigma of those days, for such hatred and fear is still, whether in Africa, the Middle East, or the United States, a major cultural and political force. It is harder now to imagine a world where persecution was not just asserted but taken as an unquestionable axiom. Alan Turing faced the impossible irony that his demand for honesty ran up against the two things, state security and homosexuality, which were the most fraught questions of the 1950s. It is not surprising that it proved impossible to contain them in a single brain. His death left a jagged edge in history, something no-one (with the extraordinary exception of his mother) wanted to talk about. My fusion of these elements into a single narrative certainly encountered criticism in 1983. But nous avons changé tout cela: since then, his life and death have been as celebrated as those of any scientific figure. Hugh Whitemore’s play Breaking the Code, based on this book, and featuring leading performers, pushed at the envelope of public acceptability. It made Alan Turing’s life a popular story in 1986, reinforced by a television version in 1997. By that time the internet had transformed personal openness. In a curious way Turing had anticipated this use of his technology, already hinted at in the risqué text-messaging of his imitation game. The love letters created by the Manchester computer (p. 478), and his message about the Norwegian youth, rendered as a nerdy computer print-out (p. 482), suggest a Turing who would have relished the opportunity for electronic communication with like-minded people.
In 2009 the British prime minister, Gordon Brown, made a statement of apology for Turing’s trial and punishment in 1952-54, framed by a wider vision of how the values of post-war European civil society had been won with his secret help. This statement was enlisted through a popular web-based petition, something impossible in 1983, but already then being mooted as the sort of thing the ‘mighty micro’ could bring about. My own comments (p. 539) in the concluding Author’s Note about future revision of printed text reflected this mood. And indeed from 1995 onwards my website has supplied updating material. In this light it is surprising that such a long volume has remained continuously in print since 1983. But perhaps one thing a traditional stack of paper still makes possible is an immersion in story-telling, and this time-consuming experience was one I certainly supplied.
As narrator I adopted a standpoint of a periscope looking just a little ahead of Alan Turing’s submerged voyage, punctuated by just a few isolated moments of prophecy. The book bears in mind that what is now the past, the 1940s and 1950s, was once the completely unknown future. This policy required an unwarranted confidence that readers would wade through the pettier details of Alan Turing’s family origins and early life, before being given any reason why this life had any significance. But it has had the happy outcome that the text has not dated as do texts resting on assertions about ‘what we know now’. So although so much has changed, the story that follows can be read without having to subtract 1983-era comment. (Of course, this is not true of the Notes, which now show what sources were available in 1983, but do not indicate a guide to ‘further reading’.)
After a further thirty years, how would I re-assess Alan Turing’s pure scientific work and its significance? My book made no attempt to trace the legacy of Turing’s work after 1954; that would be far too large a task. But naturally, the expansion of scientific discovery continually forces fresh appraisals of Turing’s achievement. His morphogenesis theory, since 2000 more actively pursued as a physico-chemical mechanism, would now require more material on the various different approaches and models. As another example, Turing’s strategy of combining top-down and bottom-up approaches to AI, and the neural nets he sketched in 1948, have acquired new significance. There has been a parallel explosion in quality and quantity of the history of science and technology since the 1970s, with many detailed studies of Turing’s papers and many more expected with the 2012 stimulus. Topics that attracted scant attention in 1983 are now the subject of lively debate.
But I would not take a radically different point of view. My division of the book into Logical and Physical was already radical, reflecting a rejection of conventional description of him as a pure logician, and portraying him as always, and increasingly, involved in the nature of the physical world. This fundamental perception could now be asserted with even greater confidence. He came to the ideas of 1936 with an unusual knowledge of quantum mechanics, and this is now a more interesting connection, for since the mid-1980s quantum computing and quantum cryptography have become important extensions of Turing’s ideas. Likewise, the renewed interest in quantum mechanics in Turing’s last year, whose significance was correctly signalled with a supersized footnote (p. 512) could now be linked more closely with his 1950 and 1951 arguments about computers and minds. These issues have arisen sharply since 1989, when Roger Penrose2 discussed the significance for minds of the uncomputable numbers Turing had discovered. Penrose himself suggested an answer which related Turing machines to a radical new view of quantum mechanics. Writing now, I would draw more attention to what is now called the physical Church-Turing thesis. Did Turing consider that the scope of the computable includes everything that can be done by any physical object? And what would this mean for his philosophy of the mind? In this light, Church’s 1937 review (p. 123) of Turing’s work has more importance than I noted. Turing’s decisive shift of focus to what could be done by algorithms, stated on page 108, I would now move from 1936 to 1941 (at p. 212). Turing’s argument about infallibility (p. 361) would deserve more analysis, as also his use of ‘random’ elements, and a number of general statements about thinking and doing in my text. But sharper sensitivity to these questions would bring out few if any new answers; it would only make more acute the questions about what Turing really thought.
Much more positive detail could now be given regarding his secret wartime work. Even in the 1992 preface to the Vintage edition, new material could be given from the third volume of F. H. Hinsley’s official history of British Intelligence. But since the mid-1990s, raw American and British documents on Second World War cryptanalysis have been officially released, and it has been possible to elucidate the internal story with far more details than Hinsley allowed. What has emerged has only enhanced the quality and significance of Bletchley Park work, and of Turing as its chief scientific figure. The Park itself is now a famous visitor attraction, though its lesson, that reason and scientific methods were the heroes of the hour, has not really caught on.
These documents show how on 1 November 1939 Turing could announce ‘the machine now being made at Letchworth, resembling, but far larger than the Bombe of the Poles (superbombe machine).’ That prefix ‘super’ dramatised the advance that my explanation (p. 183) was unable, for lack of supporting narrative detail, to highlight as the crucial breakthrough. Turing’s own 1940 report on the Enigma-breaking methods clarified how he made this advance, called ‘parallel scanning’. All of this is now working physically in the rebuilt Bombe at the Bletchley Park Museum. In addition to the document release, members of the original cryptanalytic team have written fully about the technical work, such as the details of the bigram tables which made the Naval Enigma so much more challenging, and the statistical Banburismus method. The super-fast bombes, the break into the Lorenz cipher, and the now-famous Colossus are all open to study, a great deal being due to the inspiring work of the late Tony Sale. The description in this book is now unnecessarily hazy. On the other hand, there was no room for any more codebreaking technicalities in the book, and the reader will not be seriously misled by its summary.
In particular, these revelations have only reinforced the significance of the ‘Bridge Passage’ between the logical and the physical, Turing’s top-level liaison visit to the United States in the winter of 1942-3. His report of 28 November 1942 from Washington, now released, documents the difficult and anomalous position he faced, including an initial confinement to Ellis Island (p. 242). He was not overawed by the US Navy: ‘I am persuaded that one cannot very well trust these people where a matter of judgment in cryptography is concerned.’ Something that I had heard only as rumour in 1983 has been confirmed: on 21 December a train brought Turing to Dayton, Ohio, where the US Bombes were under construction. There is also more revealed on his initiation into the most secret US speech encipherment technology. There is more on his response to it, the Delilah speech scrambler − an interim report dated 6 June 1944, and a later complete description. As a precursor of the mobile phone, this belongs to the future, whilst the Enigma was a mediocre adaptation of 1920s mechanical engineering. This new material only underlines that in the post-war period, Turing had a unique knowledge of the most advanced American technology, as it emerged from victory in 1945.
This fact draws further attention to the question of what he did for GCHQ after 1948. In the 1992 preface I floated the suggestion that this might have been connected with the now famous Venona problem of Soviet messages. But there has been no comparable release of GCHQ or MI5 documents on 1948-54 to indicate the nature of his work, or to show how the British (and American) State dealt with the arrest and trial. The recently published history of GCHQ3 opens by saying that ‘Today it is more important than ever — yet we know almost nothing about it’.
No Turing Diaries have emerged to reveal the enigma of Alan Turing’s inner life, or to pose new puzzles; no new lovers have told stories. No great treasure troves of correspondence have come to light. But a few gems of personal writing surfaced too late for the 1983 book, and were included in the 1992 preface. They are given again here.
A cosy continuity between King’s College, Cambridge, and the pre-war codebreaking establishment is evoked by some brief letters placed in the King’s archive in 1990. ‘Dilly Knox, who is my boss, sends you greetings,’ wrote Turing on 14 September 1939 to the Provost, John Sheppard. ‘It is always a joy to have you here’, wrote back the Provost, encouraging him to visit. The economist J. M. Keynes, who looked after the question of Turing’s fellowship for the duration of the war, also knew the older generation of codebreakers (and indeed had apparently enjoyed an intimate relation with the ‘boss’). These connections lend further colour to my description (p. 148) of how in 1938 Turing’s interest in ciphers could have been transmitted to the British government, thus making possible his fateful appointment.
The following account, which in 1983 was only available in Polish, also concerns the early months of the war.4 It settles the question raised in note (4.10) as to whether Turing was the personal emissary who took the new perforated sheets to the Polish and French cryptanalysts. Indeed he was: there is no mistaking his voice in this account of their farewell supper.
In a cosy restaurant outside Paris staffed by Deuxième Bureau workers, the cryptologists and the chiefs of the secret decryptment center, Bertrand and Langer, wished to spend an evening in a casual atmosphere free of everyday concerns. Before the dishes ordered and the choice wine selected for the occasion had been served, the attention of the diners was drawn to a crystal flower glass with flowers, placed on the middle of the tablecloth. They were delicate rosy-lilac flowers with slender, funnel-shaped calyces. It was probably Langer who uttered their German and then their Polish names: “Herbstzeitlose … Zimowity jesienne….”
This meant nothing to Turing, as he gazed in silence at the flowers and the dry lanceolate leaves. He was brought back from his reverie, however, by the Latin name, Colchicum autumnale (autumn crocus, or meadow saffron), spoken by mathematician-geographer Jerzy Rózycki.
“Why, that’s a powerful poison!” said Turing in a raised voice.
To which Rózycki slowly, as though weighing each word, added: “It would suffice to bite into and suck at a couple of stalks in order to attain eternity.”
For a moment there was an awkward silence. Soon, however, the crocuses and the treacherous beauty of the autumnal flowers were forgotten, and an animated discussion began at the richly laid table. But despite the earnest intention of the participants not to raise professional questions, it proved impossible to get completely away from Enigma. Once again, there was talk of the errors committed by German operators and of the perforated sheets, now machine-rather than handmade, which the British sent in series from Bletchley to the Poles working at Gretz-Armainvillers, outside Paris. The inventor of the perforated sheets, Zygalski, wondered why their measurements were so peculiar, with each little square being about eight and a half millimeters on a side.
“That’s perfectly obvious,” laughed Alan Turing. “It’s simply one-third of an inch!”
This remark in turn gave rise to a dispute as to which system of measures and currency, the traditionally chaotic British one or the lucid decimal system used in France and Poland, could be regarded as the more logical and convenient. Turing jocularly and eloquently defended the former. What other currency in the world was as admirably divided as the pound sterling, composed of 240 pence (20 shillings, each containing 12 pence)? It alone enabled three, four, five, six or eight persons to precisely, to the penny, split a tab (with tip, generally rounded off to a full pound) at a restaurant or pub.
The dark tone of Turing’s knowledge of poisonous plants, arising unexpectedly in the midst of secret work and mathematical banter, recalls the manner of his death. The shock of that event is vividly portrayed by another first-account, that written by Turing’s housekeeper Mrs Clayton on the night of Tuesday 8 June 1954:
My dear Mrs Turing
You will by now have heard of the death of Mr Alan. It was such an awfull shock. I just didn’t know what to do. So I flew across to Mrs Gibson’s and she rang Police & they wouldn’t let me touch or do a thing & I just couldn’t remember your address. I had been away for the weekend and went up tonight as usual to get his meal. Saw his bedroom light on the lounge curtains not drawn back, milk on steps & paper in door. So I thought he’d gone out early & forgot to put his light off so I went & knocked at his bedroom door. Got no answer so walked in, Saw him in bed he must have died during the night. The police have been up here, again tonight for me to make a statement & I understand the inquest will be Thursday. Shall you or Mr [John] Turing be coming over[?] I feel so helpless & not able to do anything. The Webbs removed last Wed. & I don’t know their new address yet. Mr & Mrs Gibson saw Mr Alan out walking Mon. evening he was perfectly all right then. The weekend before he’d had Mr Gandy over for the weekend & they seemed to have had a really good time. The Mr & Mrs Webb came to dinner Tues. & Mrs Webb had aftern[oon] tea with him Wed. the day she removed. You do know you have my very deepest sympathy in your great loss & what I can do to help at this end you know I will continue to do so.
Yours respectfully, S. Clayton
This account indicates how the police took charge of the house immediately, leaving open the possibility that there was information in official hands not made public at the inquest. It is now in the archive at King’s College.
The police also feature in two valuable letters written by Alan Turing himself to his friend Norman Routledge, and now also in the archive. The first, undated, must be from early 1952:
My dear Norman,
I don’t think I really do know much about jobs, except the one I had during the war, and that certainly did not involve any travelling. I think they do take on conscripts. It certainly involved a good deal of hard thinking, but whether you’d be interested I don’t know. Philip Hall was in the same racket and on the whole, I should say, he didn’t care for it. However I am not at present in a state in which I am able to concentrate well, for reasons explained in next paragraph.
I’ve now got myself into the kind of trouble that I have always considered to be quite a possibility for me, though I have usually rated it at about 10:1 against. I shall shortly be pleading guilty to a charge of sexual offences with a young man. The story of how it call came to be found out is a long and fascinating one, which I shall have to make into a short story one day, but haven’t the time to tell you now. No doubt I shall emerge from it all a different man, but quite who I’ve not found out.
Glad you enjoyed broadcast. J[efferson] certanly was rather disappointing though. I’m rather afraid that the following syllogism may be used by some in the future
Turing believes machines think
Turing lies with men
Therefore machines do not think
Yours in distress, Alan.
The allusion to the traditional syllogism about Socrates, who drank the hemlock, is an extraordinary piece of black humour. (It also stands as a superb example of how Turing himself fused the elements of his life.) The opening of the letter is perhaps equally remarkable in its absurdly off-hand description of six years of crucial wartime work, and in its inexplicable statement that the work had not involved any travelling.
The second is dated February 22, and must be from 1953:
My dear Norman
Thanks for your letter. I should have answered it earlier.
I have a delightful story to tell you of my adventurous life when next we meet. I’ve had another round with the gendarmes, and it’s positively round II to Turing. Half the police of N. England (by one report) were out searching for a supposed boyfriend of mine. It was all a mare’s nest.
Perfect virtue and chastity had governed all our proceedings. But the poor sweeties never knew this. A very light kiss beneath a foreign flag under the influence of drink, was all that had ever occurred. Everything is now cosy again except that the poor boy has had rather a raw deal I think. I’ll tell you all when we meet in March at Teddington. Being on probation my shining virtue was terrific, and had to be. If I had so much as parked my bicycle on the wrong side of the road there might have been 12 years for me. Of course the police are going to be a bit more nosy, so virtue must continue to shine.
I might try to get a job in France. But I’ve also been having psychoanalysis for a few months now, and it seems to be working a bit. It’s quite fun, and I think I’ve got a good man. 80% of the time we are working out the significance of my dreams. No time to write about logic now!
Ever, Alan
The style is a reminder that whilst Turing’s plain-speaking English might be compared with that of Orwell or Shaw, it also had a strong element of P. G. Wodehouse. Both letters perhaps indicate a state of denial about the seriousness with which those in charge of the nosy ‘sweeties’ would contemplate his Euro-adventures.
Alan Turing used logarithms of betting odds as the key to the work he had done for the ‘racket’ of cryptography, and his sustained fascination with probability is illustrated by that reference to a one-in-ten chance of being caught. In his 1953 stoic humour there is a link with innocent Anti-War undergraduate days of twenty years earlier, when he analysed Alfred Beuttell’s Monte Carlo gambling system. While the tectonic forces of geopolitics ground away, Alan Turing dodged his way through as a nimble, insouciant, individual. The lucky streak did not last for ever.
As well as these addenda, this Preface should also confess to corrigenda. Inevitably, a number of errors are perpetuated by reprinting this text. Here are some examples. Note (2.11) on normal numbers understates the significance of normal numbers and of his friend David Champernowne’s 1933 contribution. It seems possible that Turing’s study of such infinite decimals suggested his model of ‘computable numbers’. The note (3.40) on Turing’s work on the Skewes number is inaccurate: his incomplete manuscript actually dates from about 1950 when he briefly resumed this work, and corresponded briefly with Skewes. Audrey née Bates (p. 401) did more interesting and substantial work than is suggested; her Master’s thesis involved representing Church’s lambda calculus on the Manchester computer, an advanced idea which was never published. This sharpens the point made on the footnote on that page, concerning how Turing failed to turn his vision for programming and logic into the creation of a lively school of research and innovation. One clue to the problems he faced comes from her recollection that ‘Max Newman made the immortal statement that “there is nothing to do with computers that merits a Ph.D.”’ The NDRC (p. 300) was the US National Defense Research Committee; a machine called EDVAC (p. 355, footnote) was built. In 1945-47 Alan Turing lodged in Hampton village, a mile south of the Hampton Hill incorrectly mentioned on page 317, and the house is now marked by a blue plaque, as indeed are the places of his birth and death. Further additional and corrective material may be found on www.turing.org.uk.
The curious cocktail of topics in this Centenary Preface is also offered as an aperitif for the story itself, inviting the reader to travel back over that now full century, and to enter the world of 1911. In making that journey as author, I had the peculiar experience of living a previous life. The strangeness is now doubled since I am as far now removed from that Reagan era as it was from Eisenhower’s. The landscape has changed: the science-fiction ‘2001’ in my Author’s Note has become well-trodden history, and Turing’s scientific ‘least waste of energy’ now has a more urgent meaning. But the Victorian roots I drew upon, one English, one American, need no revision or apology. I chose a setting with the binary classicism of Lewis Carroll’s mathematical chessboard, on which Alan Turing was the pawn. But I also imbued it with Whitman’s romance of the ‘history of the future’. These dreams from the nineteenth century still speak to the crimes and follies of the twenty-first.
1 Martin Davis, The Universal Computer, Norton, 2000.
2 Roger Penrose, The Emperor’s New Mind, OUP, 1989.
3 Richard J. Aldrich, GCHQ: The uncensored story of Britain’s most secret intelligence agency, Harper, 2010.
4 W. Kozaczuk, tr. C. Kasparek, Enigma…, Arms and Armour Press, 1984. The original Polish text was published in Warsaw, 1979.