Life and Legacy of Alan Turing : Life and Legacy of Alan Turing
Alan Mathison Turing (1912-1954) : Alan Mathison Turing (1912-1954) The founder of computer science
Mathematician
Philosopher
Codebreaker
Strange visionary
A man before his time
Birth : Birth Father Julius (Indian Civil Service), serving in the Madras Presidency, married Ethel Sara Stoney (daughter of the chief engineer of the Madras railways)
Conceived in British India, born in a nursing home in Paddington, London on 23 June 1912
The second and last child (after his brother John) of Julius Mathison and Ethel Sara Turing.
upper-middle-class in the peculiar sense of the English class system.
Childhood in India : Childhood in India Alan Turing shared with his elder brother (John F. Turing, who became a London solicitor) a childhood rigidly determined by the demands of class and the exile in India of his parents.
Until his father's retirement from India in 1926, Alan Turing and his elder brother John were fostered in various English homes where nothing encouraged expression, originality, or discovery.
Science for him was an extra-curricular passion, first shown in primitive chemistry experiments. But he was given, and read, later commenting on its seminal influence, a popular book called Natural Wonders Every Child Should Know.
At Sherborne School : At Sherborne School At twelve he expressed his conscious fascination seeking freshly minted answers to fundamental questions.
Despite this, he was successfully entered for Sherborne School.
The headmaster soon reported: "If he is to be solely a Scientific Specialist, he is wasting his time at a Public School." The assessment of his establishment was almost correct.
Influence of Christopher Morcom : Influence of Christopher Morcom The stimulus for effective communication and competition came only from contact with another very able youth, a year ahead of him at Sherborne, to whom Alan Turing found himself powerfully attracted in 1928.
He, Christopher Morcom, gave Turing a vital period of intellectual companionship — which ended with Morcom's sudden death in February 1930.
Mind and Matter : Mind and Matter His thoughts turned to the question of how the human mind, and Christopher's mind in particular, was embodied in matter; and whether accordingly it could be released from matter by death.
This question led him deeper into the area of twentieth century physics, first helped by A. S. Eddington's book The Nature of the Physical World, wondering whether quantum-mechanical theory affected the traditional problem of mind and matter.
Undergraduate at King’s College, Cambridge Univ : Undergraduate at King’s College, Cambridge Univ As an undergraduate at King's College, Cambridge from 1931, he entered a world more encouraging to free-ranging thought.
His 1932 reading of the then new work of von Neumann on the logical foundations of quantum mechanics, helped the transition from emotional to rigorous intellectual enquiry.
At the same time, this was when his homosexuality became a definitive part of his identity.
The special ambience of King's College gave him a first real home.
Life at King’s College : Life at King’s College His association with the so-called anti-War movement of 1933 did not develop into Marxism, nor into the pacifism of his friend and occasional lover James Atkins, then a fellow undergraduate mathematician, later musician.
He was closer in thought to the liberal-left economists J. M. Keynes and A. C. Pigou.
His relaxations were found in rowing, running, and later in sailing a small boat.
Fellow of King’s College, Cambridge : Fellow of King’s College, Cambridge A distinguished degree in 1934 followed by a Fellowship of King's College in 1935 and a Smith's Prize in 1936 for work on probability theory
His uniqueness of mind, however, drove him in a direction none could have foreseen.
Into the world of Logic and Mathematics : Into the world of Logic and Mathematics By 1933 Turing had already introduced himself to Russell and Whitehead's Principia Mathematica and so to the area of mathematical logic.
Bertrand Russell had thought of logic as a solid foundation for mathematical truth, but many questions had since been raised about how truth could be captured by any formalism.
In particular, in 1931 Gödel had shattered Russell's picture by showing the incompleteness of mathematics: the existence of true statements about numbers which could not be proved by the formal application of set rules of deduction.
The Question of Decidability : The Question of Decidability In 1935, Turing learnt from the lecture course of the Cambridge topologist M. H. A. Newman that a further question, posed by Hilbert, still lay open.
It was the question of Decidability, the Entscheidungsproblem. Could there exist, at least in principle, a definite method or process by which it could be decided whether any given mathematical assertion was provable?
To answer such a question needed a definition of 'method' which would be not only precise but compelling. This is what Turing supplied.
An Abstract Machine : An Abstract Machine He analyzed what could be achieved by a person performing a methodical process, and seizing on the idea of something done 'mechanically', expressed the analysis in terms of a theoretical machine able to perform certain precisely defined elementary operations on symbols on paper tape.
He presented convincing arguments that the scope of such a machine was sufficient to encompass everything that would count as a 'definite method.'
Daringly he included an argument based on the transitions between 'states of mind' of a human being performing a mental process.
The Turing Machine : The Turing Machine The triple correspondence between logical instructions, the action of the mind, and a machine which could in principle be embodied in a practical physical form, was Turing's definitive contribution.
Having made this novel definition of what should count as a 'definite method' — in modern language, an algorithm — it was not too hard to answer Hilbert's question in the negative: no such decision procedure exists.
Work Preempted : Work Preempted In April 1936 he showed his result to Newman; but at the same moment the parallel conclusion of the American logician Alonzo Church (Princeton) became known, and Turing was robbed of the full reward for his originality.
His paper, On Computable Numbers with an application to the Entscheidungsproblem, had to refer to Church's work, and was delayed until August 1936.
Turing Vs Church : Turing Vs Church However it was seen at the time that Turing's approach was original and different; Church relied upon an assumption internal to mathematics, rather than appealing to operations that could actually be done by real things or people in the physical world.
Subsequently, the concept of the Turing machine has become the foundation of the modern theory of computation and computability.
The Universal Turing Machine : The Universal Turing Machine His work introduced a concept of immense practical significance: the idea of the Universal Turing Machine.
A Universal Turing machine can be made do what any other particular Turing machine would do, by supplying it with the standard form describing that Turing machine. One machine, for all possible tasks.
The abstract Universal Turing Machine naturally exploits what was later seen as the 'stored program' concept essential to the modern computer: it embodies the crucial twentieth-century insight that symbols representing instructions are no different in kind from symbols representing numbers.
The idea of Modern Computer : The idea of Modern Computer Computers, in the modern sense, did not exist in 1936.
Turing created these concepts out of his mathematical imagination.
Nine years later, the electronic technology tried and tested to make it practical to transfer the logic of his ideas into actual engineering.
PhD from Princeton : PhD from Princeton Turing spent two years at Princeton University enrolled as a graduate student in 1936.
Turing did not shoot to fame. He worked on algebra and number theory. On an extension of his ideas in ordinal logics earned him a Ph.D
This was connected to the question of the nature of mind, as Turing's interpretation of his ideas suggested that human 'intuition' could correspond to uncomputable steps in an argument.
But Turing never pursued this line of development after 1938.
Study of Ciphers : Study of Ciphers He also spent time at Princeton making a cipher machine based on using electromagnetic relays to multiply binary numbers.
He saw a link from 'useless' logic to practical computation.
Although not one of the political intellectuals of the 1930s, Turing followed current events and was influenced in studying ciphers by the prospect of war with Germany.
Return to Cambridge : Return to Cambridge In 1938, Turing was offered a temporary post at Princeton by von Neumann but instead he returned to Cambridge.
He had no University lectureship; in the year 1938-39 he lived on his King's College fellowship, as logician and number theorist.
Unusually for a mathematician, he joined in Wittgenstein's classes on the philosophy of mathematics; unusually again, he engineered gear-wheel parts for a special machine to calculate the Riemann Zeta-function.
On the Enigma Cipher : On the Enigma Cipher Publicly, he sponsored the entry into Britain of a young German Jewish refugee.
Secretly, he worked part-time for the British cryptanalytic department, the so-called Government Code and Cypher School.
His appointment was caused by the failure of pre-scientific methods to penetrate the mechanical Enigma cipher used by Germany.
No significant progress was made, however, until the gift of vital ideas and information in July 1939 from Poland.
The Bomba, machine for Enigma decryption : The Bomba, machine for Enigma decryption Upon British declaration of war on 3 September 1939, Turing took up full-time work at the wartime cryptanalytic headquarters, Bletchley Park.
Their ideas was embodied in a machine called a Bomba. This was the result of Turing's generalisation of the Polish Bombe into a far more powerful device, capable of breaking any Enigma message where a small portion of plaintext could be guessed correctly.
The Turing-Welchman Bombe : The Turing-Welchman Bombe Another Cambridge mathematican, W. G. Welchman, made an important contribution, but the critical factor was Turing's brilliant mechanisation of subtle logical deductions.
In contrast, the more complex Enigma methods used in German Naval communications were generally regarded as unbreakable.
Happy to work alone on a problem that defeated others, Turing cracked the system at the end of 1939, but it required the capture of further material by the Navy, and the development of sophisticated statistical processes, before regular decryption could begin in mid-1941.
The “Professor” of Bletchley Park : The “Professor” of Bletchley Park By 1942 Alan Turing was the genius loci at Bletchley Park, famous as 'Prof', shabby, nail-bitten, tie-less, sometimes halting in speech and awkward of manner, the source of many hilarious anecdotes about bicycles, gas masks, and the Home Guard; the foe of charlatans and status-seekers, relentless in long shift work with his colleagues, mostly of student age.
To one of these, Joan Clarke, he proposed marriage, and was gladly accepted. But then he retracted, telling her of his homosexuality.
U-boat Enigma Crisis : U-boat Enigma Crisis By the end of 1941, as the United States entered the war, the battle of the Atlantic was moving towards Allied advantage.
Turing crossed the Atlantic in November 1942, for highest-level liaison not only on the desperate U-boat Enigma crisis, but on the electronic encipherment of speech signals between Roosevelt and Churchill.
Hut 8 was a section at Bletchley Park tasked with solving German naval Enigma messages. The section was led by Turing.
Breaking of U-boat Enigma : Breaking of U-boat Enigma Turing's section 'Hut 8', which deciphered Naval and in particular U-boat messages, then became a key unit at Bletchley Park.
Before his return in March 1943 from US, logical weaknesses in the changed U-boat system had been brilliantly detected, and U-boat Enigma decryption was effectively restored for the rest of the war. With the battle of the Atlantic regained for the Allies, crisis resolved, chess champion C. H. O'D. Alexander, hitherto Turing's deputy, took charge of Hut 8.
Towards the End of the War : Towards the End of the War Turing became an all-purpose consultant to the by now vast Bletchley Park operation.
Turing himself devoted much time to learning electronics: ostensibly for creating his own, elegant speech secrecy system
He was awarded an OBE- Order of the British Empire
But he had another and more ambitious end in view: in the last stage of the war he planned the embodiment of the Universal Turing Machine in electronic form, or in effect, invented the digital computer.
Practical Modern Computer : Practical Modern Computer In 1944, Alan Turing was almost uniquely in possession of three key ideas:
his own 1936 concept of the universal machine
the potential speed and reliability of electronic technology
the inefficiency in designing different machines for different logical processes.
Combined, these ideas provided the principle, the practical means, and the motivation for the modern computer, a single machine capable of handling any programmed task.
He was spurred even more by a fourth idea: that the universal machine should be able to acquire and exhibit the faculties of the human mind. In 1944, he spoke to Donald Bayley of 'building a brain'.
Again Preempted : Again Preempted For the second time, he experienced being pre-empted by a parallel American publication, in this case the EDVAC plan for an electronic computer, with Von Neumann's name attached in 1945.
This worked to Turing's advantage (American competition stimulating the National Physical Laboratory to plan a rival project, to which he was appointed a Senior Principal Scientific Officer).
His nominal superior J. Womersley steered Turing's design towards formal approval in early 1946 as the Automatic Computing Engine, or ACE.
Building a Brain : Building a Brain Turing's detailed computer scheme was drawn up in a continuation of wartime spirit.
Turing knew that superior technology would soon transform design: his emphasis was on speed in every sense, and in the exploitation of the universal machine concept.
This meant, in particular, implementing arithmetical functions by programming rather than by building in electronic components, a concept different from that of the American-derived designs.
Programming Languages : Programming Languages Turing projected a computer able to switch at will from numerical work to algebra, codebreaking, file handling, or chess-playing.
Methods for handling subroutines included a suggestion that the machine could expand its own programs from an abbreviated form, ideas well ahead of contemporary American plans.
In 1947, he depicted a national computer centre with remote terminals, and the prospect of the machine taking over more and more of its own programming work.
His Abbreviated Code Instructions in 1947 marked the beginning of programming languages.
Failure of ACE : Failure of ACE But not a single component of the ACE was assembled, and Turing found himself without any influence in the engineering of the project.
The lack of cooperation, very different from the wartime spirit, he found deeply frustrating.
From October 1947, the NPL allowed, or perhaps preferred, that he should spend the academic year at Cambridge.
On Neural Nets : On Neural Nets Rather than publish these fundamental principles of computing, he spent his time not in mathematics or technology but in neurology and physiology.
Out of this came a pioneering paper on what would now be called neural nets, written to amplify his earlier suggestions that a sufficiently complex mechanical system could exhibit learning ability. This was submitted to the NPL as an internal report, and never published in his lifetime.
Meanwhile the NPL made no advance with the construction of the ACE, and as Turing's position fell back, other computer projects at Cambridge and Manchester took the lead.
As cross-country Runner : As cross-country Runner Although losing in the race to implement a universal machine, and slow to communicate or compete in the game of scientific priority, Turing ran very competitively in a literal sense.
After the war he developed his strength in cross-country running with frequent long-distance training and top-rank competition in amateur athletics.
He would amaze his colleagues by running to scientific meetings, beating the travellers by public transport, and only an injury prevented his serious consideration for the British team in the 1948 Olympic Games.
Alan Turing (on the bus steps) with other members of the Walton Athletic Club, an amateur club based in Walton, Surrey, an outer suburb of south-west London. : Alan Turing (on the bus steps) with other members of the Walton Athletic Club, an amateur club based in Walton, Surrey, an outer suburb of south-west London.
Running in 1946 From The Times, 25 August 1947 : Running in 1946 From The Times, 25 August 1947
At Manchester Univ : At Manchester Univ On his 1945 appointment to the chair of pure mathematics at Manchester University, he had negotiated a large Royal Society grant for the construction of a computer.
Newman strongly promoted Turing's principle of the stored-program computer, but unlike Turing, intended no personal involvement with engineering.
He conveyed the basic principles to the leading radar engineer F. C. Williams, who had been attracted to Manchester, and the latter's brilliant innovation made possible a rapid success: Manchester in June 1948 had the world's first practical demonstration of Turing's computer principle.
Alan Turing (right) at the console of the Manchester computer : Alan Turing (right) at the console of the Manchester computer
As Deputy Director of Computing at Manchester : As Deputy Director of Computing at Manchester In May 1948, Newman offered Turing the post as Deputy Director of the computing laboratory at Manchester University.
Turing accepted, resigned from the NPL, and moved in October 1948.
Turing at Manchester could perhaps have led the world in software development.
However, his work on machine-code programming at Manchester, produced only as a working manual, was limited in scope.
Computing Machinery and Intelligence : Computing Machinery and Intelligence There followed a confused period, in which Turing hovered between new topics and old.
He revisited his 1939 calculation of the Riemann zeta-function with the use of the prototype computer; he pursued the question of computability within the algebra of group theory.
Out of this confused era arose, however, the most lucid and far-reaching expression of Turing's philosophy of machine and Mind, the paper Computing Machinery and Intelligence which appeared in the philosophical journal Mind in 1950.
The Turing Test : The Turing Test The wit and drama of the Turing Test (a test of a machine's capability to perform human-like conversation - a human judge engages in a natural language conversation with two other parties, one a human and the other a machine; if the judge cannot reliably tell which is which, then the machine is said to pass the test) has proved a lasting stimulus to later thinkers, and the paper a classic contribution to the philosophy and practice of Artificial Intelligence research.
But he had apparently no influence on the American foundation of Artificial Intelligence later in the 1950s.
FRS : FRS He modelled hypothetical chemical reactions on the circle and the plane, and for the repetitive numerical simulation required to test his ideas, became the first serious user of an electronic computer for mathematical research.
He was elected to Fellowship of the Royal Society in July 1951, for the work done fifteen years before, but equal originality was on the way: his first successful work on The Chemical Basis of Morphogenesis was submitted as a paper that November.
Long overlooked, it was a founding paper of modern non-linear dynamical theory.
On Morphogenetic Theory : On Morphogenetic Theory His work on the morphogenetic theory continued.
He developed his theory of pattern formation out of instability into the realm of spherical objects, such as the Radiolaria, and also on the cylinder, as a model of plant stems.
He set as a particular goal the explanation for the appearance of the Fibonacci numbers in the leaf patterns of plants — most noticeable in the close-packed spirals of sunflower heads and fir cones.
Slide46 : The program below, which is in Turing's own hand, formed
part of his study of the development of the fir cone.
On Quantum Physics : On Quantum Physics He refreshed his youthful interest in quantum physics, studying the problem of wave-function reduction in quantum mechanics, with a hint that he was considering a non-linear mechanism for it.
He took a new interest in the representation of elementary particles by spinors, and in relativity theory.
Alan Turing's Crisis : Alan Turing's Crisis A factor in his life unknown to most around him was that he had also continued to work for GCHQ, the post-war successor to Bletchley Park, on the basis of a personal connection with Alexander, now its director.
Since 1948, known homosexuals had become ineligible for security clearance.
Turing, now therefore excluded, spoke bitterly of this to his onetime wartime colleague
Crisis Intensified : Crisis Intensified Alan Turing was arrested and came to trial on 31 March 1952, after the police learned of his sexual relationship with a young Manchester man.
He made no serious denial or defense, instead telling everyone that he saw no wrong with his actions.
Rather than go to prison he accepted, for the period of a year, injections of oestrogen intended to neutralise his libido.
Another intense crisis in March 1953, involving police searching for a visiting Norwegian who had come to see him (Concern over the foreign contacts of one acquainted with state secrets)
Crisis Intensified … : Crisis Intensified … Although unable to tell his friends about questions of official secrecy, in other ways he actively sought much greater intimacy of expression with them and with a Jungian therapist.
Eccentric, solitary, gloomy, vivacious, resigned, angry, eager, dissatisfied — these had always been his ever-varying characteristics, and despite the strength that he showed the world in coping with outrageous fortune, no-one could safely have predicted his future course.
Death of Turing : Death of Turing He was found by his cleaner when she came in on 8 June 1954.
He had died the day before of cyanide poisoning, a half-eaten apple beside his bed.
His mother believed he had accidentally ingested cyanide from his fingers after an amateur chemistry experiment, but it is more credible that he had successfully contrived his death to allow her alone to believe this.
The coroner's verdict was suicide.
He died while in the middle of this groundbreaking work, leaving a large pile of handwritten notes and some programs. This material is still not fully understood.
The Turing Award : The Turing Award ACM's most prestigious technical award is accompanied by a prize of $100,000.
Given to an individual selected for contributions of a technical nature made to the computing community.
The contributions should be of lasting and major technical importance to the computer field.
Financed by the Intel Corporation.
Turing Award Recipients : Turing Award Recipients 1966 A.J. Perlis 1967 Maurice V. Wilkes 1968 Richard Hamming 1969 Marvin Minsky 1970 J.H. Wilkinson 1971 John McCarthy 1972 E.W. Dijkstra 1973 Charles W. Bachman
1974 Donald E. Knuth 1975 Allen Newell 1975 Herbert A. Simon 1976 Michael O. Rabin 1976 Dana S. Scott 1977 John Backus 1978 Robert W. Floyd 1979 Kenneth E. Iverson
1980 C. Antony R. Hoare 1981 Edgar F. Codd 1982 Stephen A. Cook 1983 Ken Thompson 1983 Dennis M. Ritchie 1984 Niklaus Wirth 1985 Richard M. Karp 1986 John Hopcroft 1986 Robert Tarjan 1987 John Cocke
Turing Award Recipients … : Turing Award Recipients … 1988 Ivan Sutherland 1989 William (Velvel) Kahan 1990 Fernando J. Corbato' 1991 Robin Milner 1992 Butler W. Lampson 1993 Juris Hartmanis 1993 Richard E. Stearns 1994 Edward Feigenbaum 1994 Raj Reddy 1995 Manuel Blum 1996 Amir Pnueli 1997 Douglas Engelbart
1998 James Gray 1999 Frederick P. Brooks, Jr. 2000 Andrew Chi-Chih Yao 2001 Ole-Johan Dahl 2001 Kristen Nygaard 2002 Ronald L. Rivest 2002 Adi Shamir 2002 Leonard M. Adleman 2003 Alan Kay 2004 Vinton G. Cerf 2004 Robert E. Kahn
Conclusions : Conclusions Alan Turing appears now (in four inadequate words) as the founder of computer science
These words were not spoken in his own lifetime
A man before his time
He may be seen in a different light in the future
Slide56 : Thanks