Who was Alan Turing?

Alan Turing was not well known during his lifetime, but today he is famous for being a passionate British mathematician and gay icon, who created modern computing and played a key and important role in the Allied victory over Nazi Germany in WW2.

Early Life and Childhood

Alan Turing's father worked in the British administration of India, due to this he spent much of his young life separated from his parents. At 13 years old, he was sent to Sherborne School, a large boarding school in Dorset.
Alan Turing, aged 15, Sherborne School.
Alan Turing, aged 15, Sherborne School.
Young Alan with friends (including Christopher)
Young Alan with friends (including Christopher)


The rigid education system gave his free-ranging scientific mind little encouragement, so he often read books that were much more advanced than the classes on his own free time.
Turing was not the best at most subjects, he only did good in his math and science classes. His headmaster said about him, "If he is to be solely a Scientific Specialist, he is wasting time at a Public School."
The situation changed when Alan Turing became intensely attracted to another able pupil, Christopher Morcom. Christopher helped Alan communicate more and become an academic success. Christopher suddenly died from tuberculosis. Devastated, Turing wanted to believe that Christopher's mind lived on. This emotional turmoil created a scientific fascination with the problem of mind and brain that underlays his later work.Alan come out of his shell. The two created secret codes to be able to write notes to one another in class, and they would always look for ways to create and decipher new codes. Turing was inspired to communicate more and became an academic success. Then

King's College and Founding Computer Science

King's College, University of Cambridge.
King's College, University of Cambridge.

Turing won a scholarship to King's College, Cambridge, and took the Mathematics degree with distinction. He thrived in this new culture that encouraged his scientific interests. At the young age of 22, he was elected to a fellowship. He was already on track for a distinguished career in mathematics, yet his unusual interest in finding practical uses for abstract mathematical ideas pushed him in an altogether different direction.In 1936, Turing published a paper that is now recognized as the foundation of computer science. He was focused on determining which mathematical functions are computable. His answer involved the creation of the universal Turing Machine. He invented the idea of an 'Universal Machine' that could decode and perform any set of instructions. After completing his baccalaureate and master's degree with honors he accepted a year's fellowship to visit Princeton University, later staying to earn his PhD in mathematics. There his dissertation on ordinal logics made yet another important contribution to computer science.
How does a Turing machine work? click for a simple demonstration
On Computable Numbers, With An Application To The Entschedungsproblem By A. M. Turing

Making The Bombe and Breaking the Enigma Code

The 'Bombe'
The 'Bombe'

After two years at Princeton, developing ideas about secret ciphers, Turing returned to Britain and joined the government's code-breaking department at Bletchley Park.
The team there was trying to develop techniques and construct machines capable of decoding German diplomatic and military messages. He played a crucial role in the design of this equipment and in the development of procedures for breaking the codes.The work at Bletchley was critical to the Allied successes in Europe, and Turing was highly decorated for his contributions.

A Brief Engagement with Joan Clarke

In 1941, Turing's section, 'Hut 8', mastered the German Submarine communication system that was
The Team at Bletchley Park.
The Team at Bletchley Park.
vital to the battle of the Atlantic. In the course of this exciting work, Alan Turing developed a great friendship with another mathematician, Joan Clarke. Turing proposed to her, but the day after he told her of his 'homosexual tendencies', and the engagement soon ended. After this, he became more confident in developing his homosexual life. Meanwhile, the war took a new turn as America joined the war.


Video: My Engagement to Alan Turing by Joan Clarke (Murray)



Click here to learn more about Joan Clarke's remarkable career

Electronic Connections and Designing a First Computer

Alan Turing worked on other technical innovations during the war - mainly, a system to encrypt and
The pilot version of the ACE built in 1950
The pilot version of the ACE built in 1950
decrypt spoken telephone conversations. Code named Delilah, it was successfully demonstrated using a recording of one of Winston Churchill speeches, but was never used in actions. It did, however, give Turing hands-on experience working with electronics, and led to a position at the National Physical Laboratory (NPL), where he worked on what he sometimes described as an 'electronic brain'. In march 1946 Turing produces a detailed design for a Electronic version of his Turing Machine, it was called the Automatic Computing Engine (ACE.) This was a digital computer in the modern sense, storing programs in it's memory. His report emphasized the unlimited range of applications opened up by this technical revolution, and software developments far ahead of similar American developments. Sadly, his relationship with NPL went south and he got increasingly bored with how slow Pilot ACE was taking to build. He left NPL in 1948, before a pilot version of the ACE was finally completed in 1950.

Artificial Intelligence: Can Machines Think?

Turing moved to the University of Manchester, where electronic engineers had already demonstrated
A team of scientists work on the Baby
A team of scientists work on the Baby

a very small stored-program computer called 'the Baby' - formally known as the Manchester Small-Scale Experimental Machine. Now he focused on the use of computers. His main theme was investigating the power of a computer versus human thought. In 1950, he published a philosophical paper including the idea of an 'imitation game' to compare human thoughts with machine outputs, later called the Turing Test. This paper remains his best know work and was a very important contribution to the field of Artificial Intelligence. One of Turing's most famous quotes is on the challenge of machine intelligence: "We can only see a short distance ahead, but we can see plenty there that needs to be done."
Take an interactive tour of the Baby
Computing Machinery and Intelligence by A. M. Turing

Spots, Stripes and Flower Petals

Turing turned to a completely new and different scientific project, it was the problem of understanding the biological patterns - spots, stripes, flower petals - of nature. He proposed an explanation in terms of chemical interactions and developed equations for them. He completed a paper on this theory in 1951, and it has since become a classic and is still the subject of intense investigation 60 years later. In the same year he was elected a Fellow of the Royal Society for his earlier work. Scientists later confirmed his thesis on 'morphogenesis'
The Chemical Basis of Morphogenesis by A. M. Turing

Gross Indecency

Alan Turing
Alan Turing

All male homosexual activity was illegal until 1967, and Turing was prosecuted when an affair with a
young man came to the notice of the police. He made a statement lacking any repentance and was treated severely. He was given two choices: going to prison for two years or probation on the
condition of having hormonal treatment which was, in effect, a chemical castration. He chose the later, as to continue his work. His security clearance was revoked, ending ongoing work with the government code breaking department. His reaction was very defiant and brave, especially when he escaped British law by going abroad to Norway and Greece.
Video: Benedict Cumberbatch reads Alan Turing's Letter to Norman Routledge: "Yours in Distress"

His Final Year

Defined as a security risk, Turing was harassed by police surveillance. Alan Turing was found dead in bed by his cleaner on 8 June 1954. He had died from cyanide poisoning the day before. A partly eaten apple lay next to his body. The coroner's verdict was suicide. His mother argued that he has accidentally ingested cyanide during one of his chemistry experiments, but he most likely planned his death as to make his mother think this.
It is rumored that the apple logo is inspired by Alan Turing's death
It is rumored that the apple logo is inspired by Alan Turing's death

A Royal Pardon

The Queen visits Bletchley Park and studies an Enigma machine
The Queen visits Bletchley Park and studies an Enigma machine

In December 2013, Alan Turing was granted a posthumous royal pardon, formally cancelling his criminal conviction. It followed a four-year campaign supported by tens of thousands of people, including scientists Stephen Hawking and Richard Dawkings. Opinion was divided on whether singling out an individual in this way did true justice to a situation in which thousands of gay men have been criminalized.
A year later, a multi award winning movie "the imitation game" is released based on Alan Turing's life.