Turing at 100

In the April 4th Princeton Alumni Magazine, “Daybreak of the Digital Age: The world celebrates the man who imagined the computer”, by W. Barksdale Maynard: a piece on Alan Turing, the great mathematician (and, during WWII, an extraordinary code-breaker) who got his Ph.D. from Princeton in 1938. His 100th birthday comes on June 23rd, to celebrations in Princeton and in the U.K. There’s even a commemorative stamp, in the Britons of Distinction series for this year:

Alas, the stamp depicts, not Turing, but the Bombe, the electromechanical device used by the World War II codebreakers at Bletchley Park to decipher messages encoded by Nazi Germany using Enigma machines.

In a little while, I’ll get to my connections to Turing. But first, various bits of background.

The stamps. The Royal Mail issues commemorate “some notable personalities of our past … from the worlds of science, politics, invention and the arts”. In particular:

Inventor Thomas Newcomen’s first atmospheric steam engine dates from 1712. [300 years ago]

Born in 1812: Gothic Revival architect and interior designer Augustus Pugin best known for the interior of the Palace of Westminster [200 years]

Born in 1862: Composer Frederick Delius, Designer and textile artist May Morris, Ghost story writer MR James, and Quaker relief worker and Social reformer Joan Mary Fry.  [150 years]

Born in 1912: SOE operative Odette Hallowes, contralto singer Kathleen Ferrier, Alan Turing, Bletchley Park code breaker and computer visionary. [100 years]

The new Coventry Cathedral, Sir Basil Spence architect, opened in 1962. [50 years]

[On Odette Hallowes: the Special Operatives Executive sent her into Nazi-occupied France to work with the French underground; she was captured, imprisoned, and sentenced to be executed, but survived the war in the Ravensbrück concentration camp.]

Turing at Princeton, from PAW:

Turing arrived in Princeton in October 1936, moving into 183 Graduate College and living alongside several of his fellow countrymen — enough for a “British Empire” versus “Revolting Colonies” softball game. A star runner, Turing enjoyed playing squash and field hockey and canoeing on Stony Brook. Still, Turing made few close friends. He was shy and awkward, with halting speech that has been imitated by actor Derek Jacobi in the biopic movie Breaking the Code. Being homosexual, Turing felt like an outsider.

Soon the postman delivered proofs of Turing’s article for a London scientific journal. The young author made corrections, then mailed it back: “On Computable Numbers,” surely one of the epic papers in history.

Princeton likes to take some credit — in 2008, a ­PAW-convened panel of professors named him Princeton’s second-most influential alum, after only James Madison 1771 — but Turing actually wrote the paper at Cambridge.

… [Turing’s adviser Alonzo] Church praised his student’s paper and popularized the label “Turing machine.” But Turing kept a certain distance from his professors, with Church recalling years later that he “had the reputation of being a loner and rather odd,” even by rarified Fine Hall standards. When Turing presented “On Computable Numbers” in a lecture to the Math Club in December 1936, attendance was sparse, much to his disappointment. “One should have a reputation [already] if one hopes to be listened to,” Turing wrote to his mother glumly.

(Turing’s Ph.D. dissertation, “Systems of Logic Based on Ordinals”, was unrelated to computation but was in any case a major contribution to mathematical logic. After defending it, he returned to England as the war loomed.)

The gay story: from the Wikipedia entry:

Turing’s homosexuality resulted in a criminal prosecution in 1952, when homosexual acts were still illegal in the United Kingdom. He accepted treatment with female hormones (chemical castration) as an alternative to prison. He died in 1954, just over two weeks before his 42nd birthday, from cyanide poisoning. An inquest determined it was suicide; his mother and some others believed his death was accidental. On 10 September 2009, following an Internet campaign, British Prime Minister Gordon Brown made an official public apology on behalf of the British government for the way in which Turing was treated after the war.

And now he gets a stamp. And, at Princeton, an exhibition in Firestone Library feraturing Turing’s dissertation and graduate file; a lecture later this month by mathematician Andrew Hodges, author of the 1983 biography Alan Turing: The Enigma; and a three-day conference in May on Turing’s contributions.

Turing and me. Turing machines — the abstract automata devised by Turing — played a big role in my mathematics education at Princeton, largely through Stephen C. Kleene’s Introduction to Metamathematics (1952) and Martin Davis’s Computability and Unsolvability (1958). And then I took a course from Alonzo Church (who was in his 30s when he directed Turing and lived into his 90s), and he was on the orals committee for my senior thesis (on the theory of formal languages), 24 years after Turing defended his dissertation — also in Fine Hall.

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