Alan Turing
1912  1954
While addressing a problem in the arcane field of mathematical
logic, he imagined a machine that could mimic human reasoning.
Sound familiar?
By PAUL GRAY for Time Magazine
If all
Alan Turing had done was answer, in the negative, a vexing
question in the arcane realm of mathematical logic, few
nonspecialists today would have any reason to remember him. But
the method Turing used to show that certain propositions in a
closed logical system cannot be proved within that system — a
corollary to the proof that made Kurt Godel famous — had
enormous consequences in the world at large. For what this
eccentric young Cambridge don did was to dream up an imaginary
machine — a fairly simple typewriterlike contraption capable
somehow of scanning, or reading, instructions encoded on a tape
of theoretically infinite length. As the scanner moved from one
square of the tape to the next — responding to the sequential
commands and modifying its mechanical response if so ordered —
the output of such a process, Turing demonstrated, could
replicate logical human thought.
The device in this inspired mindexperiment quickly acquired a
name: the Turing machine. And so did another of Turing's
insights. Since the instructions on the tape governed the
behaviour of the machine, by changing those instructions, one
could induce the machine to perform the functions of all such
machines. In other words, depending on the tape it scanned, the
same machine could calculate numbers or play chess or do
anything else of a comparable nature. Hence his device acquired
a new and even grander name: the Universal Turing Machine.
Does this concept — a fairly rudimentary assemblage of hardware
performing prodigious and multifaceted tasks according to the
dictates of the instructions fed to it — sound familiar? It
certainly didn't in 1937, when Turing's seminal paper, "On
Computable Numbers, with an Application to the
Entscheidungsproblem," appeared in "Proceedings of the London
Mathematical Society." Turing's thoughts were recognized by the
few readers capable of understanding them as theoretically
interesting, even provocative. But no one recognized that
Turing's machine provided a blueprint for what would eventually
become the electronic digital computer.
So many ideas and technological advances converged to create the
modern computer that it is foolhardy to give one person the
credit for inventing it. But the fact remains that everyone who
taps at a keyboard, opening a spreadsheet or a wordprocessing
program, is working on an incarnation of a Turing machine.
Turing's 1937 paper changed the direction of his life and
embroiled a shy and vulnerable man ever more directly in the
affairs of the world outside, ultimately with tragic
consequences.
Alan Mathison Turing was born in London in 1912, the second of
his parents' two sons. His father was a member of the British
civil service in India, an environment that his mother
considered unsuitable for her boys. So John and Alan Turing
spent their childhood in foster households in England, separated
from their parents except for occasional visits back home.
Alan's loneliness during this period may have inspired his
lifelong interest in the operations of the human mind, how it
can create a world when the world it is given proves barren or
unsatisfactory.
At 13 he enrolled at the Sherbourne School in Dorset and there
showed a flair for mathematics, even if his papers were
criticized for being "dirty," i.e., messy. Turing recognized his
homosexuality while at Sherbourne and fell in love, albeit
undeclared, with another boy at the school, who suddenly died of
bovine tuberculosis. This loss shattered Turing's religious
faith and led him into atheism and the conviction that all
phenomena must have materialistic explanations. There was no
soul in the machine nor any mind behind a brain. But how, then,
did thought and consciousness arise?
After twice failing to win a fellowship at the University of
Cambridge's Trinity College, a lodestar at the time for
mathematicians from around the world, Turing received a
fellowship from King's College, Cambridge. King's, under the
guidance of such luminaries as John Maynard Keynes and E.M.
Forster, provided a remarkably free and tolerant environment for
Turing, who thrived there even though he was not considered
quite elegant enough to be initiated into King's inner circles.
When he completed his degree requirements, Turing was invited to
remain at King's as a tutor. And there he might happily have
stayed, pottering about with problems in mathematical logic, had
not his invention of the Turing machine and World War II
intervened.
Turing, on the basis of his published work, was recruited to
serve in the Government Code and Cypher School, located in a
Victorian mansion called Bletchley Park in Buckinghamshire. The
task of all those so assembled — mathematicians, chess
champions, Egyptologists, whoever might have something to
contribute about the possible permutations of formal systems —
was to break the Enigma codes used by the Nazis in
communications between headquarters and troops. Because of
secrecy restrictions, Turing's role in this enterprise was not
acknowledged until long after his death. And like the invention
of the computer, the work done by the Bletchley Park crew was
very much a team effort. But it is now known that Turing played
a crucial role in designing a primitive, computerlike machine
that could decipher at high speed Nazi codes to Uboats in the
North Atlantic.
After the war, Turing returned to Cambridge, hoping to pick up
the quiet academic life he had intended. But the newly created
mathematics division of the British National Physical Laboratory
offered him the opportunity to create an actual Turing machine,
the ACE or Automatic Computing Engine, and Turing accepted. What
he discovered, unfortunately, was that the emergency spirit that
had shortcircuited so many problems at Bletchley Park during
the war had dissipated. Bureaucracy, red tape and interminable
delays once again were the order of the day. Finding most of his
suggestions dismissed, ignored or overruled, Turing eventually
left the NPL for another stay at Cambridge and then accepted an
offer from the University of Manchester where another computer
was being constructed along the lines he had suggested back in
1937.
Since his original paper, Turing had considerably broadened his
thoughts on thinking machines. He now proposed the idea that a
machine could learn from and thus modify its own instructions.
In a famous 1950 article in the British philosophical journal
Mind, Turing proposed what he called an "imitation test," later
called the "Turing test." Imagine an interrogator in a closed
room hooked up in some manner with two subjects, one human and
the other a computer. If the questioner cannot determine by the
responses to queries posed to them which is the human and which
the computer, then the computer can be said to be "thinking" as
well as the human.
Turing remains a hero to proponents of artificial intelligence
in part because of his blithe assumption of a rosy future: "One
day ladies will take their computers for walks in the park and
tell each other, 'My little computer said such a funny thing
this morning!'"
Unfortunately, reality caught up with Turing well before his
vision would, if ever, be realized. In Manchester, he told
police investigating a robbery at his house that he was having
"an affair" with a man who was probably known to the burglar.
Always frank about his sexual orientation, Turing this time got
himself into real trouble. Homosexual relations were still a
felony in Britain, and Turing was tried and convicted of "gross
indecency" in 1952. He was spared prison but subjected to
injections of female hormones intended to dampen his lust. "I'm
growing breasts!" Turing told a friend. On June 7, 1954, he
committed suicide by eating an apple laced with cyanide. He was
41.
~~~<"((((((><~~~<"((((((><~~~<"((((((><~~~<"((((((><~~~<"((((((><~~~
The British mathematician Alan Mathison Turing (19121954) was
noted for his contributions to mathematical logic and to the
early theory, construction, and use of computers.
Alan Turing was born in London, England, on June 23, 1912. Both
his parents had upper middle class origins, and his father
continued that tradition as an administrator in the Indian civil
service. With his father off in India, Turing was sent away to
private boarding schools. After some early problems with social
adjustment, he distinguished himself in mathematics and science.
Turing's exceptional mathematical abilities were first generally
recognized in his college years (19311936) at King's College of
Cambridge University. His most important mathematical work, "On
Computable Numbers, " was written in Cambridge in 1936. In this
paper Turing answered a question of great significance to
mathematical logic  namely, which functions in mathematics can
be computed by an entirely mechanical procedure. His answer was
phrased in terms of a theoretical machine (today known as the
"Turing machine") which could mechanically carry out these
computations. Embodied in the Turing machine idea is the concept
of the stored program computer.
In 1936 Turing was awarded a Proctor fellowship to visit
Princeton University for a year. There he came in contact with
Alonzo Church, a professor of mathematics working on problems in
logic related to those addressed by Turing in his 1936 paper. He
decided to remain at Princeton an additional two years to write
a doctoral dissertation under Church's direction on ordinal
logics.
Soon after Turing's return to England Britain was drawn into
World War II. He joined the Government Code and Cypher School in
Bletchley Park, located between Oxford and London, where a
massive effort was underway to break German codes which had been
encyphered by machine. Turing played an important role (still
partly classified) in the design of equipment and development of
techniques to break these codes.
Work at Bletchley provided Turing with valuable experience in
electronics and with specialpurpose calculating equipment which
served him well after the war. In 1945 he moved to the National
Physical Laboratory (NPL) in Teddington, England, to assume
responsibilities for designing an electronic computer to be used
in government work. Turing drew up plans for the ACE computer,
an ambitious stored program computer utilizing vacuum tubes for
switching and mercury delay lines for storage. A scaled down
version completed in 1950, known as Pilot ACE, was one of the
earliest operating stored program computers. Pilot ACE served
many important functions, including aircraft design, for many
years.
Meanwhile, dissatisfied with progress on his project at NPL,
Turing accepted a position at Manchester University where a
large computer, the Mark I, was being built. His position as
chief programmer of the Mark I allowed him the opportunity to
program the computer to do mathematics, play chess and other
games, investigate automatic language translation, and do
cryptanalysis. This was probably the first major attempt to use
a stored program computer for noncomputational activities.
Turing's work on computers influenced the design of early
computers built by the English Electric and Bendix companies.
However, of more enduring significance were his theoretical
contributions to automata theory and artificial intelligence.
The 1936 paper and the concept of the Turing machine is the
starting point of the modern theory of automata, and Turing
anticipated many of the fundamental questions. During and after
the war Turing began to investigate and champion the field of
artificial intelligence. To his credit are the Turing Test (a
test for determining whether a machine can be claimed to be
thinking), a series of papers arguing against the most common
objections to the possibility of intelligent machinery, and the
recognition that scientists should approach the problem of
artificial intelligence through the programming of stored
program computers rather than through the construction of robots
that mimic human actions. Turing also made a number of other
contributions to mathematical logic, algebra, statistics, and
morphogenesis (the study of biological forms).
Turing died in his home in Manchester, England, of cyanide
poisoning. His death, ruled to be suicide by the coroner, may
have been the result of a depression caused by chemotherapy. The
courts had mandated this treatment as a result of his conviction
for public practice of homosexuality, then a criminal offense in
Britain.
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