Science_ The Definitive Visual Guide ( PDFDrive )

1890–1970

MATH EMATICIAN AN D CRYPTANALYST B o r n 1 9 1 2 D i e d 1 9 5 4

Alan Turing

“ We can only see a short distance
ahead, but we can see plenty there
that needs to be done.”

ALAN TURING, “COMPUTING MACHINERY AND INTELLIGENCE”, 1950

A pioneer in the fields of computing science through a guided reading machine, reading instructions
and artificial intelligence, Alan programme, although he neglected from a tape. Later known as
a “Turing machine”, this
Turing was one of the founders of his classics. He was accepted on a described the working of a
computer before the technology
modern computer degree course at King’s existed to build such a machine.

science. His work on College, Cambridge, to Cracking codes

algorithms led to the study mathematics. Gaining his PhD at Princeton
in 1938, Turing then returned
concept of an abstract to Britain, where he was
approached by the Government
“machine” that was The Turing machine Code and Cypher School to
work on deciphering codes of
fundamental to the At Cambridge, Turing the German Enigma machine
(see pp.342–43). At first he
development of studied for the worked for them only part time,
while starting the construction
computers, as well as mathematical tripos. of a mechanical computing
device back at Cambridge, but
a test that considered After graduating after the outbreak of World
War II he moved to Bletchley
in a practical way how he followed Max Park, headquarters of the Code

far a machine can be Newman’s course Alan Turing
Photographed here in 1951, Turing is widely
said to be “intelligent” on the foundations recognized as the visionary of the general-
purpose computer. Not only was he responsible
(see pp.380–81). Later, of mathematics, for the creation of the first practical prototype,
he also foresaw the limitations that computers
his interests diversified producing a dissertation would theoretically encounter.

into chemistry and entitled On the Gaussian

developmental biology. Error Function. The

Turing was born into Turing the athlete dissertation earned
a middle-class family Turing, who ran as a relief from stress, Turing a fellowship
in London, England, reached world-class Marathon standards. at King’s College,
but he was brought In a 1948 cross-country race he finished where he worked on
up by friends when ahead of Tom Richards, who won the probability theory; he

his parents returned to silver medal in the 1948 Olympics. later studied under

India, where his father Alonzo Church at

worked as a civil servant. He attended Princeton University. In a paper

Sherborne School, a public school in published in 1936 he proposed an

Dorset, where he voraciously pursued abstract device that mathematically

his interests in mathematics and modelled the operation of a computing

INVENTION

ELECTRONIC STORED-PROGRAM COMPUTER

A stored-program computer stores not only data but also its
programmed instructions within its writable
random access memory. Between 1946 and
1947 Turing formulated designs for a large
computer of this type, the ACE, but
its development was postponed.
The Pilot ACE, a smaller model
based on Turing’s designs,
was first demonstrated in
1950. It superseded
earlier computers that
were either not fully
electronic or used only
read-only memory.

344

ALAN TURING

TIMELINE

O 23 June 1912 Alan Turing is born in Maida
Vale, London. His father, who works for the
Indian Civil Service, wants Alan to be brought up
in England. When he is about one year old his
parents return to India, leaving him with friends
of the family in Hastings.

O 1926 Takes the Common Entrance Examination
for entry to public school, and is accepted at
Sherborne School in Dorset.

O February 1930 His best school-friend,
Christopher Morcom, dies of bovine tuberculosis.
Turing, greatly affected by his death, questions
his own religious faith and becomes an atheist.

O 1931 Fails to win a scholarship to Trinity College,
Cambridge, but is accepted by his second
choice, King’s College, to study mathematics.

O 1935 Elected Fellow of King’s College for his
dissertation in probability theory, in which he
proves the central limit theorem.

Bletchley Park O 1936 Publishes On Computable Numbers, with
The urgent wartime task at Bletchley Park was to break the an Application to the Entscheidungsproblem. In
German Enigma cypher, used for military and intelligence this paper he introduces the abstract machine,
communications, and convey decoded information to the later called a “Turing machine”.
Allied military. About 10,000 people were involved.

The Turing–Welchman Bombe O 1936 Travels to the US and studies at Princeton
University under Alonzo Church, later gaining a
and Cypher School, to devote himself To decode Enigma transmissions, Turing calculated PhD in mathematical logic.
full time to code-breaking. With his that a machine capable of replicating 60 German
colleague, Gordon Welchman, he Enigma machines would be required. Conceived O 1939 After war begins, Turing works at the
developed the “Bombe”, a computing with the help of Gordon Welchman and built by Government Code and Cypher School at
machine based on work done by Polish Harold “Doc” Keen, the machine, named the Bletchley Park. He helps develop the “Bombe”
Bombe, was installed at Bletchley Park in August to decode messages from the Enigma machine.

cryptographers, and successfully broke 1940. In all, about 200 bombes were built. O 1942–43 Goes to the US to liaise with American
experts on cryptanalysis.
the Enigma code. Subsequent, more

complex German codes were also sought to apply his mathematical O 1945 Is awarded the OBE for his war services.

eventually deciphered, and he was theories to biology, which culminated O 1945 Designs a computer for the National
Physical Laboratory in London. Because of its
awarded the OBE in 1945. in a paper on morphogenesis (the size and complexity, work on its construction is
delayed until after Turing has left the laboratory.
Stored-program computer development of form and pattern in
living organisms) in 1952.

Turing was invited to work at the National O 1947 Returns to Cambridge for a sabbatical year.
He explores interests such as neurology and
Physical Laboratory in London, where he Trial and suicide physiology, and becomes interested in athletics.

used his experience of Colossus, the However, in that same year, during the

code-breaking computer (see p.343), investigation of a break-in at his home, O 1948 Is offered a readership at the Mathematics
Department of the University of Manchester,
to design an Automatic Computing he naively admitted to a homosexual where he works in the computing laboratory.

Engine (ACE). This would have been affair with the intruder. He was tried

the first-ever stored-program computer, and convicted for homosexuality, O 1950 Publishes Computing Machinery and
Intelligence in the journal Mind, studying the
but its construction fundamental questions of
computing and artificial
was delayed and “ Machines take me by surprise intelligence and introducing
it did not run its the “Turing test” to determine
whether a machine can be
first program with great frequency.” called “intelligent”.
until 1950.

Disillusioned by ALAN TURING, “COMPUTING MACHINERY AND INTELLIGENCE”, 1950

the delay, he

accepted a readership at Manchester which was a serious offence at that O 1951 Is elected a
Fellow of London’s
University in 1948. Here he studied the time, and offered the choice of either a Royal Society.

question of how far a machine can be prison sentence or hormone treatment.

considered capable of “thinking”. He Rather than face jail, he underwent a O 1952 Opts for
a course of
devised an experiment to help determine series of oestrogen injections, which he hormone treatment
following a trial for
whether a computer could convince an took with characteristic good humour. homosexuality.

interrogator in conversation that it The government no longer gave him

was in fact human. The “Turing test”, security clearance for decoding work,

as it became known, is still used today although this freed him to concentrate O 7 June 1954 Dies at

to ascertain a machine’s ability to on his Manchester projects. his home in Wilmslow,

show human-like intelligence. In June 1954 he was found dead at Cheshire, of cyanide

Studies in morphogenesis his home, apparently poisoned by poisoning. The ruling
cyanide on a half-eaten apple. His
that he took his own
During the early 1950s he returned to death was ruled suicide, but his mother
life is generally TURING MEMORIAL
subjects he had pursued at Cambridge maintained that he had accidentally accepted. STATUE AT BLETCHLEY

a few years before. He was fascinated poisoned himself with chemicals he

by neurology and physiology, and he was using to silver-plate cutlery.

345

BREAKTHROUGH 1953

The Structure of DNA

It was the ultimate biological question: how does life spring from life?
By the early 1950s scientists had unraveled many of the body’s inner
workings, including the discovery that DNA carried genetic information,
but the structure of this molecule eluded them. But on a spring day in
England, in a year that a young woman was crowned Queen Elizabeth II
and Edmund Hillary conquered Everest, the mystery was solved.

New kinds of biologists, their roots exciting new technique called X-ray
in physics, emerged in the 1950s crystallography, which could provide
from a world rocked by war. At the clues towards the structure of
University of Cambridge, England, molecules. At King’s College,
Francis Crick was one such scientist. London, Maurice Wilkins and
He was joined by a precocious, young Rosalind Franklin were doing just
American called James Watson, who that. Franklin, in particular, had used
arrived at the Cavendish Laboratory her skills as a physical chemist to
in Cambridge for postdoctoral produce crystals for clear pictures,
research on viruses. Neither Watson one of which, ”Photograph 51,“
nor Crick was officially sanctioned revealed an X-ray diffraction pattern
to work on deoxyribonucleic acid in the shape of an ”X“ that Watson
(DNA), but both had been inspired and Crick correctly interpreted as
by tantalizing reports questioning being produced by a helical molecule.
its structure. They completed building their
structural model of DNA on March 7,
Proof that DNA was the molecule 1953 and published the result in the
responsible for carrying genetic scientific journal Nature on April 25,
information had already come in accompanied by a report from Franklin
1943 with an experiment by the and Wilkins. In their report Watson
American medical researcher Oswald and Crick noted that the structure
Avery. However, most scientists ”suggests a possible copying
suspected that his conclusions were mechanism for the genetic material.“
flawed; they thought that protein, Watson, Crick, and Wilkins shared
rather than DNA, had to be responsible the Nobel Prize in 1962 for
since it had the complexity necessary. Physiology or Medicine.
By the early 1950s opinion was still
divided among scientists, but Watson By the late 1950s further
and Crick were convinced that DNA experiments confirmed that the
was the true genetic material. The structure of DNA was the carrier
prospect of unlocking the secrets of of genetic information from one
DNA had been opened up by an generation to another.

The double helix
James Watson and Francis Crick present their model
of DNA in 1953. The model was built from workshop
materials in the Cavendish Laboratory of the physics
department of the University of Cambridge, England.

Rosalind Franklin
Franklin tragically died from ovarian cancer in
1958. The Nobel Prize rules prevent posthumous
nominations, so she was never fully rewarded for
her crucial X-ray diffraction image of DNA.

346