Although he had dropped away from the direct cryptanalytic work, Alan remained within the Bletchley fold, and was to be seen in the cafeteria off duty. Conversation at these times often revolved round mathematical and logical puzzles, and Alan was particularly good at taking some quite elementary problem and showing how some point of principle lay behind it – or conversely, illustrating some mathematical argument with an everyday application. It was part of his special concern for connecting the abstract and the concrete, as well as a pleasure in demystifying the higher mathematician’s preserve. It might be wallpaper patterns for an argument about symmetries. His ‘paper tape’ in Computable Numbers had the same flavour, bringing an ‘abstruse branch of logic’ down to earth with a bump.
One person who appreciated this approach was Donald Michie, to whom as a classicist it all came as fresh and new. He became very friendly with Alan, and in 1943 they began to meet every Friday evening in a pub at Stony Stratford, just north of Bletchley itself, to play chess and talk – or more often, for Donald to listen. The Prof’s chess had always been something of a joke at Bletchley, being all the more exposed to invidious comparison when the chess masters arrived. Harry Golombek had been able to give him queen odds, and still win; or when Alan resigned he was able to turn the board round and win from the position given up as hopeless. He complained that Alan had no idea how to make the pieces work together, and it might well be that as in his social behaviour, he was too conscious of what he was trying to do, to play with fluency. As Jack Good saw it, he was too intelligent to accept as obvious the moves that others might make without thinking. He always had to work it out from the beginning. There had been an amusing moment when Alan had come off a night shift (this would have been in late 1941) and then played a game with Harry Golombek in the early morning. Travis had looked in and was embarrassed to find, as he thought, his senior cryptanalyst playing while on duty. ‘Er … er … want to see you about something, Turing,’ he said awkwardly, like the housemaster catching a sixth-former with a cigarette in the toilet. ‘Hope you can beat him,’ he added to Golombek as they left the room, assuming quite wrongly that the master cryptanalyst was the champion player. But young Donald Michie was a player of Alan’s standard.
These meetings were an opportunity for Alan to develop the ideas for chess-playing machines that had begun in his 1941 discussion with Jack Good. They often talked about the mechanisation of thought processes, bringing in the theory of probability and weight of evidence, with which Donald Michie was by now familiar. The development of machines for cryptanalytic work had in any case stimulated discussion as to mathematical problems that could be solved with the mechanical aid – that of finding large prime numbers, for instance, was a topic that came up in lunchtime conversations, rather to the amazement of Flowers, the electronic engineer, who could see no point in it. But Alan’s talk went in rather a different direction. He was not so much concerned with the building of machines designed to carry out this or that complicated task. He was now fascinated with the idea of a machine that could learn. It was a development of his suggestion in Computable Numbers that the states of a machine could be regarded as analogous to ‘states of mind’. If this were so, if a machine could simulate a brain in the way he had discussed with Claude Shannon, then it would have to enjoy the faculty of brains, that of learning new tricks. He was concerned to counter the objection that a machine, however intricate its task, would only be doing what a person had explicitly designed it to do. In these off-duty discussions they spent a good deal of time on what would be said to count as ‘learning’.
Implicit in these discussions was the materialist view that there was no autonomous ‘mind’ or ‘soul’ which used the mechanism of the brain. (He had perhaps hardened his stance as an atheist, and his conversation was more free with anti-God and anti-church jokes than it would have been before the war.) To avoid philosophical discussions about what ‘mind’ or ‘thought’ or ‘free will’ were supposed to be, he favoured the idea of judging a machine’s mental capacity simply by comparing its performance with that of a human being. It was an operational definition of ‘thinking’, rather as Einstein had insisted on operational definitions of time and space in order to liberate his theory from a priori assumptions. This was nothing new – it was an entirely standard line of rationalist thought. Indeed in 1933 he had seen it on the stage, for in Back to Methuselah Shaw had a future scientist produce an artificial ‘automaton’ which could show, or at least imitate, the thought and emotions of twentieth-century people. Shaw had the ‘man of science’ assert that he had no way of drawing a line between ‘an automaton and a living organism’. Far from it being a novelty, Shaw was trying to make this argument appear a dated piece of Victoriana. Again, his Natural Wonders book had accepted the rationalist view, with a chapter called ‘Where some of the Animals do their Thinking’ which treated thought, intelligence and learning as differing only in degree as between monocellular animals and human beings. It was no new idea, therefore, when Alan talked in terms of an imitation principle: that if a machine appeared to be doing as well as a human being, then it was doing as well as a human being. But it gave a sharp, constructive edge to their discussions.
Meanwhile Donald Michie had been plucked from the Testery, and Jack Good from Hut 8, to work as Newman’s first staff on a very exciting development of the Fish analysis. Donald Michie had continued to work on refinements of the Turingismus method, reporting informally to Alan on their progress – advances reflected in the fact that at the beginning of 1943 a proportion of the Fish signals were being read regularly and with little delay. The Turing theory of statistics, with its formalisation of ‘likeliness’ and ‘weight of evidence’, and with its ‘sequential analysis’ idea, were also playing a general part in the Fish work, in which it found greater application than in the Enigma methods. But by the spring of 1943, Newman's ideas for mechanisation had begun to bear fruit. Here the new developments with electronic technology, in which the crucial steps had been taken while Alan was in America, were in themselves very significant.
The Post Office engineers had been able to install a first electronic counting machine in Hut F, where Newman and his two assistants worked, in about April 1943. This and its successors were called the ‘Robinsons’.* Although they had overcome some of the engineering problems associated with passing paper tape very rapidly through an electronic counter, these ‘Robinsons’ still suffered from many defects. They were prone to catch fire; the paper tapes were always breaking; and the counts were unreliable. This was because the slower parts of the counting process were performed by the old relays, and these produced an electrical interference effect upon the electronic components. But the fundamental technological problem was that of synchronising the ingestion of the two separate paper tapes demanded by the method. For all these reasons, the Robinsons proved too unreliable and too slow for effective cryptanalytic use. They were employed only for research purposes. There was also another fundamental difficulty, not so much physical as logical, which made the machine method too slow. In using it for the cryptanalytic process, the operator would constantly have to produce fresh tapes, resorting for this purpose to an6 ‘auxiliary machine that was used to produce the tapes which formed one of the two inputs to the Heath Robinson.’
But even before the first Robinson was finished, Flowers had made a revolutionary proposal which both solved the problem of tape synchronisation, and did away with the laborious production of fresh tapes. The idea was to store the Fish key-patterns internally, and in electronic form. If this were done, only one tape would be required. The difficulty lay in the fact that such internal storage would require the more extensive use of electronic valves. It was a suggestion regarded with deep suspicion by the established experts, Keen and Wynn-Williams. But Newman understood and supported Flowers’ initiative.
By any normal standards, this project was a stab in the technological dark. But they were not in normal times, but in the conditions of 194
3. What happened next was a development unthinkable even two years before. Flowers simply told Gordon Radley, director of the Post Office laboratories, that it was necessary for Bletchley work. Under instructions from Churchill to give Bletchley’s work absolute priority, without questions or delay, Radley had no decision to make, although the development consumed half the resources of his laboratories. Construction began in February 1943 and the machine that Flowers had envisaged was completed after eleven months of night-and-day working. No one but Flowers, Broadhurst and Chandler who together had designed the machine had been permitted to see all the parts, let alone to know what the machine was for. There were no drawings for many of the parts, only the designers’ originals; there were no manuals, no accounts, nor questions asked about materials and labour consumed. In the laboratory the machine was assembled, wired and made to work in separate sections which did not come together until the whole machine was installed and working at Bletchley in December 1943.
In three years, they had caught up with half a century of technological progress. Dillwyn Knox died in February 1943, passing just before the Italian empire he had done a good deal to undermine, and with him the pre-industrial mind. They had been forced into one scientific revolution by the Enigma, and already they were in the throes of a second. The all-electronic machine proved to be much more reliable than the Robinsons, as well as faster. They called it the Colossus, and it demonstrated that the colossal number of 1500 electronic valves, if correctly used, could work together for long periods without error. This was an astonishing fact for those trained in the conventional wisdom. But in 1943 it was possible both to think and do the impossible before breakfast.
Alan knew about all these developments, but declined the invitation to play a direct part.7 Newman built up an increasingly large and powerful group, drawing in the best talent from the other huts and from the mathematical world outside. Alan moved in the opposite direction; he was not a Newman, skilled in overall direction, and still less was he a Blackett, moving in political circles. He had not fought to retain control of naval Enigma, but had retreated before Hugh Alexander’s organising power. If he had been a quite different person, he could now have made his position one of great influence, it being the time for sitting on coordinating committees, Anglo-American committees, future policy committees. But he had no concern for finding a place in anything but scientific research itself. Other scientists were finding the war to be awarding them a power and influence denied in the 1930s, and thrived upon it. For Alan Turing, the war had certainly brought new experiences and ideas, and the chance to do something. But it had given him no taste for organising other people, and it had left his axioms unchanged. A confirmed solitary, he wanted something of his own again.
It would also take more than the Second World War to change his mother’s ideas, which in December 1943 focussed as always upon the duty of choosing Christmas presents. Alan wrote to her8 on 23 December:
My dear Mother,
Thank you for your enquiry as to what I should like for Christmas, but really I think we had better have a moratorium this year. I can think of a lot of things I should like which I know to be unobtainable, e.g. a nice chess set to replace the one that was stolen from here while I was away, and which you gave me in 1922 or so: but I know it is useless to try at present. There is an old set here that I can use till the war is over.
I had a week’s leave fairly recently.* Went up to the lakes with Champernowne and stayed in Prof. Pigou’s cottage on Buttermere. I had no idea it was worth while to go amongst the mountains at this time of year, but we had the most marvellous weather, with no rain at all and snow only for a few minutes when we were up on Great Gable. Unfortunately Champernowne caught a chill and retired to bed half-way through. This was in the middle of November, so I don’t think I’ll be taking Christmas leave until February ….
Yours, Alan
But by Christmas 1943, as the Scharnhorst was sunk with Enigma help, Alan had set out on a new project, this time something of his own. He handed over his files on American machinery to Gordon Welchman, who left Hut 6 at this point to take on an overall coordinating role. Welchman had lost interest in mathematics, but found a new life in the study of efficient organisation, and was particularly attracted to American liaison. But Alan, since returning from America, had spent a good deal of time on the devising of a new speech encipherment process. And while other mathematicians might be content to use electronic equipment, or to know about it in general terms, he was determined to build upon his Bell Labs experience and actually create something that worked with his own hands. In late 1943 he became free to devote time to some experiments.
Speech encipherment was not now regarded as an urgent problem. On 23 July 1943, the X-system had been inaugurated for conversations at top level between London and Washington (the extension to the War Room was not completed for another month). The Chiefs of Staff memorandum9 of that date stated that ‘The British experts, who were appointed to examine the secrecy [sic] of the equipment, have expressed themselves as completely satisfied’; it also listed the twenty-four British top brass, from Churchill downwards, who were allowed to use it, and the forty Americans, from Roosevelt downwards, whom they might call. This solved the problem of high-level Atlantic communications, although it meant that the British had to go cap in hand to use it, and found themselves outdone by the links to the Philippines and Australia that the Americans were busily installing. Nor did they necessarily want to have all their transmissions recorded by the Americans, the alliance never being so close that the British government confided all to the United States. There was every incentive, from the point of view of future policy, to develop an independent British high-grade speech system. It was Britain, not the United States, that was supposed to be the centre of a world political and commercial system.
But this was not undertaken, and nor did Alan’s new idea have the potential for such a development. The principle he had in mind would be impossible to apply with the variable time-delays and fading experienced with short-wave transatlantic radio transmissions. It would never be the rival of the X-system, which overcame these problems, and this was made clear at the start. It bore the mark of something that he wanted to achieve for himself, rather than of something he had been asked to provide. The war was no longer calling for his original attack on problems, and he found himself almost redundant after 1943. Neither was his idea backed with more than a token share of resources. It was like going back to early, grudging days. To pursue it he had to move to a rather different establishment. While the Bletchley industry continued, with ten thousand people now at work on rolling secrets off the production line, not only deciphering and translating but doing a great deal of the interpretation and appreciation over the heads of the services, Alan Turing gradually transferred himself to nearby Hanslope Park.
While the Government Code and Cypher School had expanded to dimensions quite unimaginable in 1939, the secret service had also mushroomed in a variety of directions. Just before the war, it had recruited Brigadier Richard Gambier-Parry to improve its radio communications. Gambier-Parry, a veteran of the Royal Flying Corps and a genial paternalist to whom junior officers would refer as ‘Pop’, had thereafter spread his wings much further. His first chance had come in May 1941 when the secret service managed to detach from MI5 the Radio Security Service, then responsible for tracking down enemy agents in Britain. It was he who had taken it over. With all such enemy agents soon under control, the role of the RSS had been diverted into that of intercepting enemy agents’ radio transmissions from all over the world. Now known as ‘Special Communications Unit No. 3’, this organisation used a number of large receiving stations centred on the one at Hanslope Park, a large eighteenth-century mansion in a remote corner of north Buckinghamshire.
Gambier-Parry had also acquired the responsibility for other aspects of secret-service work. These included providing the transmitters for the black broadcasting organisation, which began its ‘
Soldatensender Calais’ broadcasts on 24 October 1943. (The studios where journalists and German exiles concocted their ingenious falsities were at Simpson, another Buckinghamshire village.) SCU3 had further taken under its wing the manufacture of the cryptographic system Rockex, which was to be used for top-grade British telegraph signals. Such traffic now amounted to a million words a day to America alone – pre-eminently, of course, carrying Bletchley’s productions. The Rockex represented a technical improvement to the Vernam one-time teleprinter cipher system.
One problem with the Vernam principle was that the cipher-text, regarded as a teleprinter input in the Baudot code, was bound to include many occurrences of the operational or ‘stunt’ symbols, those which produced not letters but ‘line feed’, ‘carriage return’ and so forth. For this reason, the cipher-text could not be handed over to a commercial telegraph company for transmission in Morse, as was often desirable. It was Professor Bayly, the Canadian engineer at Stephenson’s organisation in New York,* who had devised a method of suppressing the unwanted characters and replacing them in such a way that the resulting cipher-text could be printed neatly on a page. This required the development of electronics which could automatically ‘recognise’ the unwanted telegraph symbols. The problem involved logical circuits such as appeared in the Colossus, albeit on a much more modest scale, using electronic switching for Boolean operations applied to the holes of telegraph tape.
Alan Turing: The Enigma: The Book That Inspired the Film The Imitation Game Page 43
