# Faces of HPC: Alan Turing

Alan Turing is considered the father of theoretical computer science, creating the ‘Turing Machine’ used in World War 2 to crack the German Enigma codes. He would later work on developing the first universal programmable machine, the ACE, and even began foundational investigations into artificial intelligence, creating his well-known ‘Turing Test.’

## Introduction

Alan Turing is best known for his pioneering work on programmable computers. After studying mathematics at Cambridge, he was invited by the British Government to work on cracking the German Enigma codes. Applying his unique skills in mathematics and logic, he developed the Bombe machine that provided the British military invaluable intelligence during the Second World War. He continued to develop the ACE, the first universal programmable computer, and even developed the Turing Test to judge hypothetical artificial intelligence. Two years after being persecuted for his homosexuality, he was found dead, declared as a suicide.

## Biography

Alan was born in London in 1912, although his parents were both stationed in India. His father was a member of the Indian Civil Service, while his mother was the daughter of the Madras Railway’s chief engineer. Rather than staying with his nuclear family in India, he was raised by family friends in England until 1926.

His mother had wanted Alan to receive a public-school education, although the academic system was not an appropriate fit for him. Incredibly intelligent, Turing was concerned with his own ideas, and did not follow the structure set out at school. He was interested in chemistry and mathematics, conducting his own informal experiments during labs, and finding his own methods for solving mathematical problems, rather than following the instructions of his teachers. Outside of school he was interested in chess and studied mathematics and quantum mechanics in his spare time. In 1930, Alan’s close friend, Christopher Morcom, passed away. The event would greatly affect Turing through his life, and inspire his meditations on mind and body, mechanics and spirit.

Turing entered Kings College, Cambridge in 1931 to study Mathematics, and finally found an environment more suited to his free-ranging mindset. Here, his interests moved towards mathematical logic.

He graduated in 1934, and attended Max Newman’s course on the foundations of mathematics. One issue that was raised dealt with finding an algorithm to determine whether or not certain mathematical propositions had attributable truth statements. After working on this problem, Turing published his 1936 paper, *On Computable Numbers, with an Application to the Entscheidungsproblem*. This paper was his first proposal of an abstract ‘Turing machine’ that could move between states using precise and finite rules, depending on symbols printed and read from a tape. Alan’s paper was published just after Alonzo Church’s – the two had unknowingly been working on the same problem.

With his new connection to Church, Alan became a graduate student in 1936 at Princeton, under Church’s supervision. Here, he continued his studies of logic, and entertained the idea of building a computer.

Returning to Cambridge in 1938, he began construction on an analogue machine, which he intended to apply to investigations of the Riemann hypothesis. He was, however, contacted by the Government Code and Cypher School to apply his work to cracking the German Enigma codes. He moved to Bletchley Park at the outbreak of the war in 1939 and worked full-time, applying his skills of mathematics, logic, code, and machine computations.

Working with Mathematician W G Welchman, Turing developed the decoding ‘Bombe’ machine, based on the earlier work of Polish mathematicians. Adapting this machine to the German Navel codes, his statistical methods and captured information allowed Bletchley to decode German signals from as early as 1941.

After the war, Turing continued to work on developing more advanced computers. In 1946, he produced designs of the Automatic Computing Engine (ACE) for the National Physical Laboratory in London. His designs for a universal digital programmable computer would prove the first of a more advanced and modern style computer. In 1948, Turing was offered a readership at the University of Manchester by Newman. Newman wrote:

*“... work was beginning on the construction of a computing machine by F C Williams and T Kilburn. The expectation was that Turing would lead the mathematical side of the work, and for a few years he continued to work, first on the design of the subroutines out of which the larger programs for such a machine are built, and then, as this kind of work became standardised, on more general problems of numerical analysis.”*

In 1950, Turing began exploring the consequences of a computerized world. In connection with his interest in the mind-body problem, he studied the issues surrounding artificial intelligence and the similarities of brains and machines. In his paper, *Computing Machinery and Intelligence*, he proposed the Turing to test a machine's ability to exhibit intelligent behaviour, and assess whether it is equivalent to that of a human.

Turing was arrested in 1952, charged with gross indecency for his homosexuality. Rather than being imprisoned, he agreed to undergo ‘correctional’ oestrogen injections. Nevertheless, he continued his work in mathematics, morphogenesis, and quantum theory.

He was found dead in 1953, and it was declared suicide by cyanide. While his mother maintains it was an accident caused by his somewhat careless informal experiments at home, with the rise of the cold war and Turing's access to sensitive government information, other historians suspect there was a higher involvement in his death. In July 2012 the House of Lords introduced a bill to grant a pardon for his offences under the Criminal Law Amendment Act 1885, of which he was convicted in March 1952. Turing was officially pardoned by Queen Elizabeth II on 24 December 2013, with immediate effect.