The Man Who Knew Too Much: Alan Turing and the Invention of the Computer (Great Discoveries)

by David Leavitt

  DAVID LEAVITT

  The Man Who Knew Too Much

  Alan Turing and the Invention of the Computer

  Dedication

  For Mark—friend, comrade, partner

  PUBLISHED TITLES IN THE GREAT DISCOVERIES SERIES

  David Foster Wallace

  Everything and More: A Compact History of ∞

  Sherwin B. Nuland

  The Doctors’ Plague: Germs, Childbed Fever, and the Strange Story of Ignác Semmelweis

  Michio Kaku

  Einstein’s Cosmos: How Albert Einstein’s Vision Transformed Our Understanding of Space and Time

  Barbara Goldsmith

  Obsessive Genius: The Inner World of Marie Curie

  Rebecca Goldstein

  Incompleteness: The Proof and Paradox of Kurt Gödel

  Madison Smartt Bell

  Lavoisier in the Year One: The Birth of a New Science in an Age of Revolution

  George Johnson

  Miss Leavitt’s Stars: The Untold Story of the Forgotten Woman Who Discovered How to Measure the Universe

  David Leavitt

  The Man Who Knew Too Much: Alan Turing and the Invention of the Computer

  William T. Vollman

  Uncentering the Earth: Copernicus and the Revolutions of the Heavenly Spheres

  David Quammen

  The Reluctant Mr. Darwin: An Intimate Portrait of Charles Darwin and the Making of his Theory of Evolution

  FORTHCOMING TITLES

  Richard Reeves on Rutherford and the Atom

  Daniel Mendelsohn on Archimedes and the Science of the Ancient Greeks

  General Editors: Edwin Barber and Jesse Cohen

  Contents

  1.The Man in the White Suit

  2.Watching the Daisies Grow

  3.The Universal Machine

  4.God Is Slick

  5.The Tender Peel

  6.The Electronic Athlete

  7.The Imitation Game

  8.Pryce’s Buoy

  Notes

  Further Reading

  Index

  1

  The Man in the White Suit

  In Alexander Mackendrick’s 1951 Ealing comedy The Man in the White Suit, Alec Guinness plays Sidney Stratton, a dithery, even childlike chemist who creates a fabric that will never wear out or get dirty. His invention is heralded as a great step forward—until the owners of the textile mills at which he was employed, along with the members of the unions representing his fellow workers, realize that it will put them all out of business. Soon enough, these perennial antagonists join forces to trap Stratton and destroy his fabric, which he is wearing in the form of a white suit. They chase him down, corner him, and seem about to murder him, when at the very last moment, the suit begins to disintegrate. Failure thus saves Stratton from the industry he threatens, and saves the industry from obsolescence.

  It goes without saying that any parallel drawn between Sidney Stratton and Alan Turing—the English mathematician, inventor of the modern computer, and architect of the machine that broke the German Enigma code during World War II—must by necessity be inexact. For one thing, such a parallel demands that we view Stratton (especially as portrayed by the gay Guinness) as at the very least a protohomosexual figure, while interpreting his hounding as a metaphor for the more generalized persecution of homosexuals in England before the 1967 decriminalization of acts of “gross indecency” between adult men. This is obviously a reading of The Man in the White Suit that not all of its admirers will accept, and that more than a few will protest. To draw a parallel between Sidney Stratton and Alan Turing would also require us to ignore a crucial difference between the two scientists: while Stratton is hounded because of his discovery, Turing was hounded in spite of it. Far from the failure that is Stratton’s white suit, Turing’s machines—both hypothetical and real—not only initiated the age of the computer but played a crucial role in the Allied victory over Germany in World War II.

  Why, then, labor the comparison? Only because, in my view, The Man in the White Suit has so much to tell us about the determining conditions of Alan Turing’s short life: homosexuality, the scientific imagination, and England in the first half of the twentieth century. Like Stratton, Turing was naïve, absent-minded, and oblivious to the forces that threatened him. Like Stratton, he worked alone. Like Stratton, he was interested in welding the theoretical to the practical, approaching mathematics from a perspective that reflected the industrial ethos of the England in which he was raised. And finally, like Stratton, Turing was “hounded out of the world” by forces that viewed him as a danger, much as the eponymous hero of E. M. Forster’s Maurice fears that he will be “hounded out of the world” if his homosexuality is discovered. Dubbed a security risk because of his heroic work during World War II, Turing was arrested and tried a year after the opening of The Man in the White Suit on charges of committing acts of gross indecency with another man. As an alternative to a prison sentence, he was forced to endure a humiliating course of estrogen injections intended to “cure” him. Finally, in 1954, he committed suicide by biting into an apple dipped in cyanide—an apparent nod to the poisoned apple in one of his favorite films, the Disney version of Snow White and the Seven Dwarfs, and one which writers on Turing in subsequent years have made much of.

  In a letter written to his friend Norman Routledge near the end of his life, Turing linked his arrest with his accomplishments in an extraordinary syllogism:

  Turing believes machines think

  Turing lies with men

  Therefore machines cannot think

  His fear seems to have been that his homosexuality would be used not just against him but against his ideas. Nor was his choice of the rather antiquated biblical locution “to lie with” accidental: Turing was fully aware of the degree to which both his homosexuality and his belief in computer intelligence posed a threat to organized religion. After all, his insistence on questioning humankind’s exclusive claim to the faculty of thought had brought on him a barrage of criticism in the 1940s, perhaps because his call for “fair play” to machines encoded a subtle critique of social norms that denied to another population—that of homosexual men and women—the right to a legitimate and legal existence. For Turing—remarkably, given the era in which he came of age—seems to have taken it as a given that there was nothing at all wrong with being homosexual; more remarkably, this conviction came to inform even some of his most arcane mathematical writings. To some extent his ability to make unexpected connections reflected the startlingly original—and at the same time startlingly literal—nature of his imagination. Yet it also owed, at least in part, to his education at Sherborne School, at King’s College during the heyday of E. M. Forster and John Maynard Keynes, and at Princeton during the reign of Einstein; to his participation in Wittgenstein’s famous course on the foundations of mathematics; and to his secret work for the government at Bletchley Park, where the necessity of contending with an elusive German cipher on a daily basis exercised his ingenuity and compelled him to loosen up his already limber mind.

  The fallout of his arrest and suicide was that for years his contribution to the development of the modern computer was minimized and in some instances erased altogether, with John von Neumann often being given credit for ideas that really originated with Turing.* Indeed, only after the declassification of documents relating to his work at Bletchley Park, and the subsequent publication of Andrew Hodges’ magisterial 1983 biography, did this great thinker begin to receive his du
e. Now he is acknowledged as one of the most important scientists of the twentieth century. Even so, most popular accounts of his work either fail to mention his homosexuality altogether or present it as a distasteful and ultimately tragic blot on an otherwise stellar career.

  I first heard about Alan Turing in the mid-eighties, when he was often recalled as a sort of martyr to English intolerance. Although I had taken a basic course in calculus in high school, in college and afterward I’d made a point of avoiding mathematics. I’d made an even greater point of steering clear of computer science, even as I grew, like most Americans, increasingly dependent on computers. Then I started to read more about Turing, and to my own surprise, I found myself becoming as fascinated by the work he’d done as by the life he’d led. Within the daunting morass of Greek and German letters, logic symbols, and mathematical formulae that enwebbed the pages of his papers, there lay the prose of a speculative and philosophical writer who thought nothing of asking whether a computer could enjoy strawberries and cream, or of resolving a bothersome problem in logic by means of an imaginary machine writing 1’s and 0’s on an endless tape, or of putting the principles of pure mathematics to the practical goal of breaking a cipher.

  Alan Turing bridged the gap between the delightfully useless and (for most people) remote landscape of pure mathematics and the factory world of industry in which the ability of a machine to multiply together giant prime numbers, or go through tens of thousands of possible letter substitutions in search of a match, or assist in the engineering of a bridge, meant the difference between financial success and failure, and in some cases between life and death. Yet it would be misleading to claim that Turing saw it as his duty or calling to effect such a bridging; on the contrary, the road he took from mathematical logic to machine building was an accidental one, and the only map he used was the one provided by his very particular, in some ways peculiar, in every way eccentric brain. He was the polar opposite of a company man, and had he been, in some sense, more “normal,” he might never have made the advances that he did. It was his status as an outsider that allowed him to make the creative leaps that marked his career, and changed the world.

  In a brief recollection published in the late fifties, Lyn Irvine, a novelist and the wife of the mathematician Max Newman, wrote of Turing, “Alan certainly had less of the eighteenth and nineteenth centuries in him than most of his contemporaries. One must go back three centuries (or on two perhaps) to place him. . . .” Her recognition of Turing as a figure who belonged to the past and the future is an insightful one, in that it emphasizes his failure to find a place for himself in the age in which he was born. “He never looked right in his clothes,” she adds a few paragraphs later,

  neither in his Burberry, well-worn, dirty, and a size too small, nor when he took pains and wore a clean white shirt or his best blue tweed suit. An Alchemist’s robe, or chain mail would have suited him, the first one fitting in with his abstracted manner, the second with that dark powerful head, with its chin like a ship’s prow and its nose short and curved like the nose of an enquiring animal. The chain mail would have gone with his eyes too, blue to the brightness and richness of stained glass.

  The alchemist took logical principles, wire, and electronic circuits, and made a machine. The knight defended the right of that machine to a future.

  If only he had been able to save himself.

  * * *

  *Martin Davis must be credited with setting the record straight on this account.

  2

  Watching the Daisies Grow

  1.

  He was a child of empire, and of the English middle class. His father, Julius, was in the Indian civil service, and it was in Chatrapur, near Madras, that Turing was conceived. Julius and Ethel Sara Turing then returned to England, where their second son was born on June 23, 1912, in a nursing home at Paddington. His full name was Alan Mathison Turing. According to his mother, “Alan was interested in figures—not with any mathematical association—before he could read and would study the numbers on lamp posts, etc.” He also showed a fondness for inventing words: “quockling” for the noise made by seagulls fighting over food, “greasicle” for “the guttering of a candle caught in a draught,” “squaddy” for squat and square. He seems to have had a hard time grasping the principle of the calendar, however, and later admitted that as a small child he was “quite unable to predict when [Christmas] would fall. I didn’t even realize that it came at regular intervals.”

  When he was six, he was sent to a small school called Hazelhurst. Already he had begun to show an incipient interest in science, once, again according to his mother, carefully concocting “a mixture in which the chief ingredient was pounded dock leaves for the cure of nettle stings, the formula for which he wrote down in all seriousness with a sense of its importance.” He also set out to compile an “encyclopaedio” [sic] and at eight wrote what his mother calls “the shortest scientific work on record,” About a Microscope, the entire text of which consisted of the line “First you must see that the lite is rite.” Mrs. Turing goes on to report, rather modestly, that she herself taught him long division, noting that “as a child he always sought to know underlying principles, and apply them. Having at school learnt how to find the square root of a given number, he deduced for himself how to find the cube root.” A drawing of him that she made in the spring of 1923 shows young Alan standing on the hockey field, stick in hand, bent over to gaze at some flowers—the caption reads, “Hockey, or Watching the Daisies Grow”—while a Hazelhurst end-of-term song included a couplet as indicative of his talents as of his attitude toward games:

  Turing’s fond of the football field

  For geometric problems the touch lines yield.

  In 1922 he received as a gift a book called Natural Wonders Every Child Should Know, by Edwin Tenney Brewster. In explaining biology, evolution, and nature, Brewster used the metaphor (very much contrary to his title) of machines. The idea that the body—and particularly the brain—could be thought of as a machine stayed with Turing and influenced the course of his future work. Brewster’s book may also have jump-started his allergy to imprecision, evidenced when he complained in a letter to his brother, John, that the mathematics master at Hazelhurst had given “a quite false impression of what is meant by x.” As his mother explains, the master’s determination to pin x “down to something much too determinate and concrete for Alan’s dawning logician’s mind” disturbed her son at least in part because he feared that the other boys in his form might be misled.

  “Hockey, or Watching the Daisies Grow,” drawn by Sara Turing and sent to Miss Dunwall, matron at Hazelhurst School, in the spring of 1923. (King’s College, Cambridge)

  After Hazelhurst, he was sent to Sherborne, one of the original public schools and the subject of Alec Waugh’s 1917 novel The Loom of Youth. Like most public schools, Sherborne aspired to be what E. M. Forster called a “world in miniature,” striving to invest in its students the political and social values of empire-building Britain and replicating most of its hypocrisies, prejudices, and double standards. Sexual experimentation, as well as romances between older and younger boys, figured prominently in the life of the public schools, even as their administrations decried such behavior as indecent. Indeed, in 1908 C. K. Scott-Moncrieff, later to become the first English translator of Proust’s À la recherche de temps perdu, was expelled from his own public school, Winchester, after he published a story called “Evensong and Morwe Song” in New Field, the school’s literary magazine. The story dealt explicitly with romantic and sexual intrigue among male students, as well as the violent reaction of the headmaster once the intrigue is exposed.

  Turing’s first term at Sherborne began just as the general strike of 1926 was breaking out; he had spent the summer in France, and as no trains were running, he had to bicycle the sixty miles to Sherborne from Southampton, a labor he undertook cheerfully and with no great anxiety. According to a report by his housemaster, Mr. O’Hanlon, his mat
hematics, in which he had started out well, was by the summer term of 1927 “not very good. He spends a great deal of time in investigations in advanced mathematics to the neglect of his elementary work.” Thus he took the time to work out, entirely on his own, Gregory’s series for tan-1x, without realizing that Gregory had beaten him to the punch by two centuries. As Mrs. Turing recalls, this discovery “was a cause of satisfaction to Alan himself. . . . On his asking if the series was correct, Colonel Randolph, his mathematics master, at first thought Alan must have got it from a book in the Library.” The colonel later told his mother that despite its originality, Turing’s form master “complained that his work was so ill-presented that he ought to be sent down.”

  Mr. Nowell Smith, the headmaster at Sherborne, called him “the Alchemist,” in part because of a report from the end of the Michaelmas term of 1927 in which O’Hanlon wrote, “No doubt he is very aggravating: and he should know by now that I don’t care to find him boiling heaven knows what witches’ brew by the aid of two guttering candles on a naked windowsill.” According to Mrs. Turing, “Alan’s only regret was that Mr. O’Hanlon had missed seeing at their height the very fine colours produced by the ignition of the vapour given off by super-heated candle grease.” Had the wind blown the candle out, the result would have been, to borrow Turing’s own term, a “greasicle.” Of course, no one could have foreseen the ominous relevance that the term “witches’ brew” would have both for Turing’s life and for his death.

  It was at Sherborne that he first began to display the stubborn literal-mindedness that would later get him into so much trouble even as it led to some of his most startling intellectual advances. For instance, when asked in an examination, “What is the locus of so and so?” (the shorthand is his mother’s), instead of providing the expected proof, he simply wrote, “The locus is such and such.” Later, when Mrs. Turing asked why he had not bothered to write out the proof, he replied that all he had been asked was “What is the locus?” That question he had answered. He was simply doing what he had been told.