Alan Turing: The Enigma (76 page)

As a theoretician of computers, von Neumann had been joined by
Norbert Wiener, the American mathematician of a slightly earlier generation, whom the war had likewise taken from group theory to machinery, although in his case the servo-mechanisms of anti-aircraft artillery had been the formative influence. Thus von Neumann and Wiener corresponded in connection with the potential of the planned EDVAC, but mostly in terms of the faculty of conditional branching corresponding to ‘feedback’. They did not discuss hierarchies of programs, nor the computer reorganising and creating its own instructions. They remained most impressed with the McCulloch and Pitts ideas, which suggested that the logical functions of electronic valves bore some similarity to the structure of neurons in the human nervous system. In a letter
¹⁵
of 29 November 1946, von Neumann wrote to Wiener of the ‘extremely bold efforts’ of Pitts and McCulloch, with which he ‘would like to put on one par the very un-neurological thesis of R. [sic] Turing.’

In the other direction, likewise, there was limited communication. The
Draft Report on the EDVAC
was there at the NPL, and Alan continued to make use of its notation for logical networks. David Rees, who attended the Moore School lectures on behalf of the Manchester interest, reported back to Alan and Jim Wilkinson for ten days or so. But the American plans had no particular influence on the ACE project, Alan being notably sceptical about the prospects for the Iconoscope, the storage medium on which the Americans were pinning their hopes. They did not think of the American development as a rival; it was simply another project. The ACE was Alan Turing’s own thing, like naval Enigma, like the Delilah. It was not, however, developing in quite the same way.

Although the wartime spirit lived on amongst the huts and bombsites of 1946, the ACE section did not flower with the
camaraderie
of Hut 8, or the quite remarkable
rapport
that Alan had established with Don Bayley. Mike Woodger came back from sick leave in September and found a note on his desk asking him to program BURY and UNBURY. The relationship continued in this master-and-servant way. Alan liked the earnest, rather nervous Mike Woodger, and tried to be kind, but hid it under what appeared as an abrupt, rather frightening manner. He probably did not realise the awe with which he was regarded by young people like Mike Woodger, just starting on a career. Always casting himself as the Young Turk embattled against officialdom, he still found it hard to see himself as the official in others’ eyes. He was impatient of slowness, and could not use his imagination to make communication more effective.

Jim Wilkinson was older and more experienced than Mike Woodger, but he too found many days when it was better to keep out of the way of the now somewhat isolated ‘creative anarchy’ that was Alan Turing. ‘Likeable, almost lovable …but some days depressed’, he appeared; his mercurial
temperament and his emotional attitude to his work showing clearly. It was at about this time that Alan got the long-promised promotion to Senior Principal Scientific Officer, and he took Jim Wilkinson and Leslie Fox from Goodwin’s department out to a celebration dinner in London. The train journey was spoilt by a sultry row over some mathematics, and then, as they arrived at Waterloo, the clouds cleared and he was buoyant again.

This particular argument arose because Alan had become involved in a problem of numerical analysis, the work done in Goodwin’s section. In 1943 the statistician H. Hotelling
¹⁶
had analysed the procedure for solving simultaneous equations (or, roughly equivalently, for inverting a matrix) and his result made it appear that errors would grow very rapidly as successive equations were eliminated. If this were so it would undermine the practical usefulness of the ACE. Goodwin’s section, being directly concerned with the problem, had attacked it heuristically in 1946 by solving a set of eighteen equations that had come up in an aerodynamic calculation, and Alan had joined in (notably the least competent at the detailed work), on the desk machine exercise. To their surprise, they found the final errors to be remarkably small. Alan had undertaken a theoretical analysis of why this should be. It was a typical Turing problem, needing a fresh attack, and with a concrete application. He tackled it much as he had developed a theory of probability for use at Bletchley.

This work of course, did not lie far in the past, and he set Mike Woodger some probability problems, including the one about the ‘barrels of gunpowder’. There was also professional contact arising out of wartime work. Jack Good and Newman had made a visit to the ν PL – Newman, of course, being interested in setting up his Manchester computer project – and Jack had managed to disprove Alan’s assertion that no one could write an instruction table that was free from error at the first attempt. Jack Good had also written a short book
¹⁷
on
Probability and the Weighing of Evidence
, effectively setting out the theory they had employed at Bletchley, though not its more advanced applications. The ‘sequential analysis’ method was, as it happened, soon published in America by the statistician A. Wald,
¹⁸
who had developed it independently for the testing of industrial components. Alan, in contrast, published nothing that came of his Bletchley work, except in the less direct sense that almost everything he was doing was flowing from his wartime experience added to his pre-war theory of machines.

Rather than forming new ties of friendship at the ν PL, he retained those of the war. Donald Michie, now an undergraduate at Oxford, was one of these friends, and a footnote on Alan’s October 1946 letter to Jack Good, with comments on the draft of his book, noted cryptically that ‘Donald has agreed to help and I have now got the necessary gadgets for the treasure.’ This was a reference to a proposed expedition to recover the silver bars. (David Champernowne had meanwhile realised a healthy profit in his ingots, which had remained safely in his bank.) There had been a previous
attempt with Donald Michie, who was offered the choice of either a one-third share of the total proceeds or a payment of
£5
per expedition. This was itself a nice example of the Turing theory of probability, which appealed to the odds that a perfectly rational person would be prepared to bet on an event. As a perfectly rational man, Donald Michie opted for the latter choice. The first real-life treasure hunt had been a failure, since when they went to the wood near Shenley where one bar was buried, Alan found that the landmarks had changed since 1940, and he could not locate the spot. The point of the ‘gadget’ was that it was a metal detector which Alan had designed and built himself. On the second trip, it functioned, though only to a depth of a few inches. It successfully located a great many pieces of metal under the surface of the wood, but not the silver bar. As for the second bar, he knew where that was, but they found that they were unable to apply the UNBURY routine when standing in the bed of the stream.

Such failures he would easily laugh off. This was not his only visit back to Buckinghamshire, for he spent a weekend, probably in December 1946, discussing D. Gabor’s new theory of communication
¹⁹
with Don Bayley. This time he distinguished himself by fainting when he grazed himself shaving. He had told Don long before about this reaction to blood, but this was the first time Don had seen it happen. There had also been an occasion in October 1945, when he, Don Bayley, Robin Gandy and ‘Jumbo’ Lee met up to go to a lecture on wartime radio work at the Institute of Electrical Engineers. Afterwards they had gone to Bernard Walsh’s oyster restaurant and rather hoped to be fed on the house – in which they had been disappointed. Alan had cycled into London from Teddington and had parked his bicycle outside the Soho restaurant, from which it was duly stolen.

For him to cycle the fifteen miles was not entirely characteristic, since he would quite happily take in such distances on foot. His success in the Hanslope races had been followed up. On arrival at Teddington he had joined the local Walton Athletics Club, and had taken up running as a serious amateur. He was a long-distance runner, rather than a sprinter; it was his stamina that gave him the edge in races over three miles in length. During this period he would spend two or three hours every day on training, and would run for the club on Saturday afternoons. Thus in October 1946 he wrote to his mother:

My running was quite successful in August. I won the 1 mile and 1/2 mile at the NPL sports, also the 3 miles club championship and a 3-mile handicap at Motspur Park. That was the meeting
^*
at which all the stars were trying to break records, but in fact were pulling muscles instead. Being a very humble athlete myself I was able to get away without pulling a muscle. …The track season is over now, but of course the cross country season will be beginning almost at once. I think that will suit me rather better, though the dark evenings will mean that my weekday runs will be in the dark.

He was lengthening his distance, and
working up to marathon running. If possible he would make official visits double as training runs. In particular, he would run the ten miles across west London to Dollis Hill in connection with the plodding development of the ACE delay lines. Every few months, he would run the rather longer distance of eighteen miles to Guildford, to put Mrs Turing’s social imperatives to some constructive use. It amazed everyone, but he did not care about that. It also, as Mrs Turing put it, gave him contact with men ‘in all walks of life.’

He even managed to combine running and chess. He saw something of David Champernowne from time to time, either at Oxford, where he now had a position, or at his parents’ house at Dorking. They would play ping-pong, and talk about probability theory, but they also devised a form of chess in which each player had to make his move while the other ran round the garden. Fast running would tend to prevent good thinking, so the problem was to choose the right balance. Alan was also interviewed by the
Sunday Empire News
on training hints. He might have remembered the discussion of ‘second wind’ in
Natural Wonders
, which explained how it depended upon ‘teaching’ the brain not to ‘raise such a row’ when it smelt a little carbon dioxide in the blood.

One of the difficulties of his position was that there was a good deal of carbon dioxide in the blood supplying the British brain. For all the talk of planning for the future, there was a terrible exhaustion after the war, and little eagerness to upset the apple-cart any further. In one way this became clear at once. At Hanslope, Don Bayley had continued to improve and test the Delilah. Later in 1945 he had taken it to Dollis Hill for evaluation where – hardly surprisingly – they failed to find any cryptographic weakness. In early 1946 he had taken it to the Cypher Policy Board, which was a coordinating organisation established in February 1944. He set it up in the basement of their London offices, and left it with one of their officers. They were more interested than the Post Office, and suggested to Gambier-Parry that his man might join them to continue work. But Gambier-Parry turned this down, and this refusal closed the story. The Delilah’s two neat packages of equipment, providing speech security with no more than thirty valve-envelopes, were completely forgotten. As a contribution to British technology it had been a complete waste of time.
^*

But Delilah had been part of the preparations for the ACE, and this, Alan Turing’s logical Overlord, was what mattered. The plans were all ready, and only needed the signal to start. And they did at least gain a sort of
second wind on 31 October 1946, when Mountbatten, as president of the Institution of Radio Engineers, gave a speech
²⁰
that conveyed – however inaccurately – the excitement of what had happened in the new technology of communication and control. It was as far beyond the old days of the
Glorious y
as they had been ahead of the papyrus scroll:

The war not only taught us a great deal about techniques, but it proved the occasion for new departures in application, particularly in electronics, which had enormously augmented our present human senses. Apart from radar, which aided to a remarkable degree the sense of sight, we might in future be able, by pooling and transforming the potentialities of other forms of radiation, such as light, heat, sound, X-rays, gamma-rays and cosmic rays, to receive the counterpart of radar screen pictures from inside our bodies, or even from individual body cells. Or perhaps we might receive them from the interior of the earth, or from the stars and galaxies.…there was reason to believe that facilities for impressing information and knowledge on the human brain …may be extended by the direct application of electrical currents to the human body or brain. …

The stage was now set for ‘the most Wellsian development of all’. It was considered possible to evolve an electronic brain, which would perform functions analogous to those at present undertaken by the semi-automatic portions of the human brain. It would be done by radio valves, activating each other in the way that brain cells do; one such machine was the electronic numeral [sic] integrator and computer (ENIAC), employing 18,000 valves …

Machines were now in use which could exercise a degree of memory, while some were being designed to employ those hitherto human prerogatives of choice and judgment. One of them could even be made to play a rather mediocre game of chess! …

Now that the memory machine and the electronic brain were upon us, it seemed that we were really facing a new revolution; not an industrial one, but a revolution of the mind, and the responsibilities facing the scientists to-day were formidable and serious. ‘Let us see to it,’ he concluded, ‘that we not only insist on being allowed to shoulder it; but that when we have established our right, we can also prove our fitness.’