// The Chapters
From Maida Vale to the Apple
Five acts. Forty-one years. The mind that built the future and the system that broke it.
1912 – 1938 · The Foundation
The Universal Machine
A shy, awkward boy who loved numbers and fell in love with his classmate Christopher Morcom — and then invented the theoretical computer.
Born in Maida Vale, London. His father was a civil servant in India; Alan was raised largely by strangers. At Sherborne School, he was isolated, bullied, and brilliant. He formed a deep attachment to Christopher Morcom — his intellectual companion and likely his first love. Christopher died of tuberculosis in 1930, at age 18. The grief shaped everything that followed. At Cambridge, Turing studied mathematics under Max Newman. In 1936, at age 24, he published "On Computable Numbers" — a paper that defined the theoretical limits of computation and described a "universal machine" that could compute anything computable. It is the founding document of computer science. He went to Princeton for his PhD, studying under Alonzo Church, and returned to England in 1938 — just in time for war.
Christopher
February 13, 1930 · Sherborne School
Christopher Morcom dies of bovine tuberculosis. He was Turing's closest friend and intellectual soulmate. Turing writes to Christopher's mother: "I feel sure I shall meet Morcom again somewhere and that there will be some work for us to do together." The loss drives Turing toward questions about the nature of mind and mechanism.
"On Computable Numbers"
November 12, 1936 · London Mathematical Society
Turing publishes his proof that a universal machine can compute any calculable function. The paper invents the concept of the algorithm, the stored program, and the modern computer — all as a side effect of solving a mathematical logic problem posed by David Hilbert. He is 24. The paper that founds computer science is 36 pages long.
Princeton
1936 – 1938 · Princeton University
Turing studies under Alonzo Church, who independently developed an equivalent formalism (lambda calculus). Their combined work — the Church-Turing thesis — defines what computation is. Turing also builds an electromechanical binary multiplier in the Princeton machine shop. Theory meets hardware.
Personal Life
Turing was an exceptional long-distance runner. He ran with Walton Athletic Club and his marathon time of 2 hours 46 minutes was only 11 minutes slower than the 1948 Olympic gold medalist. He told colleagues he ran to relieve the stress of work. His running was the only thing that made his body feel as free as his mind.
1939 – 1945 · The Secret War
Bletchley Park
He cracked the Enigma code. He may have shortened the war by two years. He was forbidden from telling anyone for thirty years.
On September 4, 1939 — one day after Britain declared war on Germany — Turing reported to Bletchley Park, the secret codebreaking center in Buckinghamshire. The German Enigma machine produced 158 million million million possible settings each day. Turing designed the Bombe, an electromechanical device that could systematically test Enigma configurations. At peak operation, Bletchley Park was decrypting up to 4,000 German messages per day. The intelligence, codenamed Ultra, is estimated to have shortened the war by two to four years and saved 14 million lives. Turing also cracked the even more complex Naval Enigma, breaking the U-boat codes that were winning the Battle of the Atlantic. Churchill called the Bletchley Park codebreakers "the geese that laid the golden eggs and never cackled." Every person involved was sworn to secrecy. The secret was not declassified until 1974.
The Bombe
March 14, 1940 · Hut 8, Bletchley Park
Turing's first Bombe machine, "Victory," begins operation. It tests Enigma settings using known-plaintext attacks — cribs. The machine clicks and whirs through thousands of configurations. When it stops, the operators know they've found the day's Enigma setting. The war changes that afternoon.
Breaking Naval Enigma
June 1941 · Bletchley Park
Turing cracks the Naval Enigma, used by U-boats in the Atlantic. German submarines have been sinking 500,000 tons of Allied shipping per month. With the code broken, convoys can be rerouted around wolf packs. The Battle of the Atlantic tips. Britain will not starve. Turing has saved the supply chain that keeps the island alive.
The Churchill Letter
October 21, 1941 · Bletchley Park
Turing and three colleagues write directly to Churchill, bypassing the chain of command, demanding more resources for Bletchley Park. Churchill reads the letter and writes one line to his chief of staff: "Action this day. Make sure they have all they want on extreme priority." The resources arrive within weeks.
Personal Life
At Bletchley Park, Turing became engaged to Joan Clarke, a fellow codebreaker in Hut 8. He told her he was homosexual. She said she didn't mind. He broke off the engagement anyway, unable to live the lie. They remained close friends for the rest of his life. Clarke went on to become one of Britain's finest cryptanalysts.
1945 – 1950 · The Architect
Building the Brain
He had designed the theoretical computer in 1936. Now he built the real one.
After the war, Turing joined the National Physical Laboratory and designed the Automatic Computing Engine (ACE) — one of the first detailed designs for a stored-program computer. Frustrated by bureaucratic delays, he moved to Manchester in 1948, where he worked on the Manchester Mark 1 — one of the world's first working electronic stored-program computers. In 1950, he published "Computing Machinery and Intelligence" in the journal Mind, proposing what became known as the Turing Test: if a machine can converse indistinguishably from a human, it should be considered intelligent. The paper opens with the line: "I propose to consider the question, 'Can machines think?'" Every AI system built since — including the one generating this text — exists in the intellectual shadow of that paper.
"Can Machines Think?"
October 1950 · Mind Journal
"Computing Machinery and Intelligence" proposes the Imitation Game — now called the Turing Test. If you can't tell whether you're talking to a machine or a human, does the distinction matter? The paper founds the field of artificial intelligence. Every chatbot, every language model, every AI assistant descends from this question.
The Manchester Mark 1
June 21, 1948 · University of Manchester
The Manchester Baby (Small-Scale Experimental Machine) runs its first program — a factoring algorithm that takes 52 minutes. Turing writes the programming manual. He is simultaneously the world's greatest theorist of computation and a practical programmer debugging real hardware. Theory and machine finally merge.
The Chemical Basis of Morphogenesis
August 1952 · Philosophical Transactions
Turing publishes his final great paper, explaining how biological patterns (spots on leopards, spirals on sunflowers) emerge from chemical reactions. Reaction-diffusion equations. The father of computer science, in his spare time, solves a fundamental problem in biology. The paper is decades ahead of its field.
1952 – 1954 · The Persecution
Gross Indecency
The man who saved millions was prosecuted for who he loved. The sentence was chemical castration. He lasted two years.
In January 1952, Turing began a relationship with Arnold Murray, a 19-year-old from Manchester. When Turing reported a burglary at his home, the police investigation revealed the relationship. Homosexuality was illegal in Britain under the Criminal Law Amendment Act 1885. Turing was charged with "gross indecency" — the same law used to convict Oscar Wilde. Rather than prison, he accepted chemical castration: injections of diethylstilbestrol, a synthetic estrogen that caused breast tissue growth, impotence, and depression. His security clearance was revoked. He was banned from the United States. The man who had cracked the code that helped win the war was now a convicted criminal. On June 7, 1954, his housekeeper found him dead. A half-eaten apple lay beside his bed. The inquest ruled suicide by cyanide poisoning. He was 41 years old.
The Arrest
February 1952 · Wilmslow, Cheshire
Police investigating a burglary at Turing's home discover his relationship with Arnold Murray. Turing makes no attempt to deny it. He is honest to the point of naivety — he doesn't understand why loving someone should be criminal. He is charged under Section 11 of the Criminal Law Amendment Act 1885. Conviction is certain.
Chemical Castration
March 1952 – April 1953 · Manchester
For one year, Turing receives injections of synthetic estrogen. He develops gynecomastia. His mind — the most valuable mind in British computing — is clouded by the hormones. His security clearance is revoked. GCHQ, the successor to Bletchley Park, no longer trusts the man who built its foundation. He continues working on morphogenesis. He keeps running.
The Apple
June 7, 1954 · Wilmslow, Cheshire
Turing is found dead by his housekeeper, Eliza Clayton. Beside his bed: a half-eaten apple. The inquest rules suicide by cyanide poisoning. His mother believes it was an accidental inhalation from his chemistry experiments. The apple was never tested for cyanide. He was 41. He had saved millions. He had invented the computer. He was a convicted criminal.
1954 – Present · The Reckoning
Pardon, Apology, Legacy
It took 59 years for Britain to say sorry. His face is now on the 50-pound note.
For decades, Turing's contributions were classified and his story was forgotten. The Official Secrets Act kept Bletchley Park sealed until 1974. In 2009, Prime Minister Gordon Brown issued a public apology: "We're sorry, you deserved so much better." In 2013, Queen Elizabeth II granted a posthumous royal pardon — the first in 60 years. In 2017, the "Alan Turing law" retroactively pardoned all men convicted of consensual homosexual acts. In 2021, Turing's face appeared on the Bank of England 50-pound note. The Turing Award, given by the ACM, is the Nobel Prize of computer science. Every phone, every laptop, every server, every AI system runs on principles he described in a 36-page paper in 1936. He won. He just didn't live to see it.
The Apology
September 10, 2009 · 10 Downing Street
PM Gordon Brown: "On behalf of the British government, and all those who live freely thanks to Alan's work, I am very proud to say: we're sorry, you deserved so much better." Fifty-five years after his death. The words come too late. They still needed to be said.
The 50-Pound Note
June 23, 2021 · Bank of England
Turing's face appears on the new polymer 50-pound note. Born 1912, convicted 1952, pardoned 2013, honored 2021. The note features his birth date in binary, a depiction of the Bombe, and his quote: "This is only a foretaste of what is to come." The man the state destroyed is now the face of its currency.