The Second World War showcased the courage of countless soldiers on the battlefield. However, heroism also flourished behind the scenes. Alan Turing, a brilliant mathematician, significantly impacted the war effort without ever firing a shot. He cracked the German Enigma cipher machine, a feat that mechanized intelligence and profoundly influenced the development of computers.
Alan Turing’s Early Life and Education
Born in London on June 23, 1912, Alan Turing attended Hazelhurst Preparatory School and later Sherborne School. His early years at boarding school were challenging; his clumsiness and untidy appearance drew the criticism of his peers. Yet, his exceptional mathematical abilities shone through, evident in his ability to solve complex problems without formal instruction in advanced subjects like calculus.
Though somewhat socially isolated, Turing formed a deep bond with Christopher Morcom, another student passionate about science. Their friendship, however, was tragically cut short when Morcom succumbed to illness in 1930.
Alan Turing’s University Years
Alan Turing pursued studies in mathematics at King’s College, Cambridge between 1931 and 1934, graduating with first-class honors. His transition to Cambridge was eased by architectural similarities to his previous school and the shared background of many fellow students. Importantly, Cambridge placed him at the forefront of the scientific world. His coursework emphasized the intersection of mathematics and physics, and he was exposed to the work of renowned figures such as Arthur Eddington and Paul A.M. Dirac.
During his undergraduate years, Turing became more outgoing. He actively participated in the Cambridge Boat Club, enjoyed playing bridge, and was open about his homosexuality.
Upon obtaining his master’s degree, Turing authored an influential paper titled “On Computable Numbers, with an Application to the Entscheidungsproblem.” This paper introduced the concept of the Turing Machine, a theoretical computing device that remains foundational in computer science.
Turing furthered his education at Princeton University in New Jersey. His doctoral thesis explored formalized mathematical proofs and their mechanical verification. After completing his PhD in 1938, Turing returned to the United Kingdom.
The Enigma Machine
The rise of the Nazi regime in Germany during the 1930s set a course for global conflict. This totalitarian regime, fueled by extremist beliefs, led to the suppression of democratic principles, persecution of minorities, and ultimately the start of World War II with the invasion of Poland in 1939. During this conflict, the German military relied on a complex cipher device known as the Enigma machine. Invented by Arthur Scherbius, the Enigma machine scrambled plain text into ciphertext using a system of rotors, making messages nearly impossible to intercept and understand without the proper settings.
The Enigma machine offered a staggering 159 quintillion possible combinations, with settings changing daily, leading the German forces to believe it impenetrable. However, this confidence in the code’s complexity proved to be their strategic downfall.
Bletchley Park and the Codebreakers
In 1938, British intelligence established a secret wartime operation at Bletchley Park, a country estate in Buckinghamshire. Known as the Government Code and Cypher School, this specialized unit brought together brilliant minds in mathematics and cryptography. The team, bolstered by Cambridge University academics, included the exceptional Alan Turing. Bletchley Park grew exponentially throughout World War II, peaking at 10,000 personnel and necessitating additional structures to house the codebreaking efforts.
Crucially, British codebreakers didn’t work in isolation. They were heavily influenced by the groundbreaking work of Polish mathematician Marian Rejewski and his team at the Polish Defense Ministry’s Cipher Bureau during the 1930s. This early analysis was pivotal in laying the groundwork for cracking Enigma’s sophisticated encryption.
Cracking the Enigma: Innovations of Turing, Welchman, and the Bletchley Park Team
Alan Turing, along with crucial contributions from mathematicians like Gordon Welchman, Hugh O’Donel Alexander, and Joan Clarke, made significant advances in codebreaking during World War II. One of their most notable achievements was the development of the electromechanical ‘bombe’.
Inspired by the Polish ‘bomba’ device, Turing’s machine essentially replicated the function of multiple Enigma machines in tandem. It employed rotors and a plugboard to systematically test possible solutions to decipher encrypted German communications. Welchman’s innovation of a diagonal board proved vital. This enhancement significantly optimized the bombe’s efficiency, reducing false solutions and streamlining the decryption process.
The Turing-Welchman bombe became indispensable to the Allied war effort. The Bletchley Park team tirelessly decoded German messages, providing critical tactical and strategic intelligence. Examples of its impact include locating the Bismarck in 1941 and Allied preparation for D-Day in 1944.
The Allies faced a unique challenge: protecting their ability to break the Enigma code. Direct responses to decrypted messages could alert the Germans. Strategic selectivity was vital – knowing when to act on intelligence and when to maintain the illusion of ignorance.
In 1942, Turing devised another breakthrough technique, ‘Turingery’. This method laid the groundwork for deciphering the intricate Lorenz cipher machine. Mathematician W.T. Tutte played a pivotal role in unraveling the Lorenz’s structure, ultimately allowing the Allies to access high-level German military communications.
While difficult to quantify precisely, historians credit the efforts of the Bletchley Park codebreakers with shortening the war by years and ultimately saving countless lives.
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The Final Years
By the close of 1945, Alan Turing had formulated a comprehensive design for a general-purpose computer, the Automatic Computing Engine (ACE). Yet, setbacks in the machine’s construction led to frustration, prompting Turing’s departure from the National Physical Laboratory in 1948.
Turing’s fascination with the possibility of machine intelligence grew. He delved into this concept in influential essays such as “Intelligent Machinery” (1948) and “Computing Machinery and Intelligence” (1950). Turing’s inquiries centered on whether a machine could convincingly mimic human communication, a concept now known as the Turing Test.
In 1952, while at the University of Manchester, Turing was arrested for his relationship with a nineteen-year-old man. Homosexuality was a criminal offense in Britain at the time. Pleading guilty to public indecency, Turing faced the stark choice of imprisonment or chemical castration, tragically choosing the latter.
An End and a Legacy
On June 7th, 1954, Alan Turing died by suicide at the age of forty-two. His pioneering work in mechanizing intelligence firmly establishes his position as a central figure in the evolution of computer science.
Turing’s story is also a poignant reminder of the historical persecution of the LGBTQ+ community. The Sexual Offences Act of 1967 finally decriminalized homosexuality in Britain. In 2013, Turing’s mistreatment was acknowledged with a posthumous royal pardon.
Alongside the honors bestowed upon Turing during his lifetime, including his appointment as an Officer of the British Empire, the Bank of England featured his portrait on the new fifty-pound note in 2021. This, coupled with the 2014 film “The Imitation Game,” has sparked renewed public interest in Turing’s remarkable life and contributions. He is rightfully celebrated alongside other great figures of the Second World War.
