Computer scientist Alan Turing, born in 1912, was a man light years ahead of his time. He performed groundbreaking computer science work long before the concept even existed. An artificial intelligence test he developed remains relevant today. During World War II, his cryptanalysis work helped Allied convoys safely cross the Atlantic.
Turing was also openly gay. In 1952, he was convicted for homosexuality and punished by being chemically castrated. Just two years later, he died after eating a cyanide-laced apple. An inquest ruled the death a suicide, but friends and family dispute the finding.
Now, finally, after several petitions, appeals and even an apology from prime minister Gordon Brown in 2009, Turing has finally received a pardon. It was granted on December 24 under the Royal Prerogative of Mercy after a request by Justice Minister Chris Grayling.
Turing was not the only gay man persecuted at the time. More than 50,000 other were convicted of "gross indecency," for being homosexual. Advocates for Turing hope the pardon will be extended to others.
In the meantime, Turing's legacy in computing and beyond should not be overlooked.
James Sumner, a lecturer in the history of technology at the University of Manchester, helped plan the Manchester Museum’s centenary Turing exhibition. “Alan Turing is somebody who, in recent years, has gone from being almost written out of the story of the computer’s origins to being given a very, very strong starring role,” Sumner said.
Sumner highlights Turing’s contribution here.
The Universal Computer
Turing’s now-famous scientific paper published in early 1937, "On Computable Numbers, With an Application to the Entscheidungsproblem," is by no means a beach read. Extremely difficult for the lay person to understand, the article does contain parts that sound like Turing was writing about building a computer, Sumner said.
“It’s an extraordinary thing to do in the 1930s,” he said. “None of the electronics are in place.” Instead, most who read the paper at the time saw it as an exercise in mathematical logic.
In the paper, Turing discussed a theoretical machine that could perform analysis using symbols on paper tape, according to biographer Andrew Hodges. He also put forth the idea of a universal machine that could read from any of the other Turing machines and perform any task given to it. Turing has been credited with anticipating aspects of computing such as input, output, memory and programs.
Sumner, who said he doesn’t believe in lone geniuses, noted that Turing's idea for a universal machine was built on the work of other mathematicians. But it was Turing who codified it and passed the concept on to others while pursuing his PhD at Princeton University. Those people included John Von Neumann, a computer science pioneer involved in the Manhattan Project who helped design an advanced computer architecture in 1945.
“That’s why there was that sudden rush of new computing concepts on both sides of the Atlantic during the Second World War,” Sumner said.
Turing had experience with cryptography prior to World War II but in 1939 he got called to work full time at the government’s decryption establishment in Bletchley Park. His task was to help figure out the German Enigma cipher. Such a code wasn’t one where simply understanding the principle meant cracking it permanently -- that’s a popular misconception, Sumner said.
The Enigma machine settings, used for encoded Nazi communications, changed daily. To speed along the process of checking these settings, Turing developed a special electro-mechanical machine that automated the computations. This made attempts to decipher messages more manageable. The machine had arrays of cylindrical drums that made ticking noises as they spun, so it was called a “bombe.”
Turing’s section of Bletchley Park worked on the German Navy Enigma, and knowing where German submarines were positioned, as well as their planned movements, allowed the Allies’ convoys to dodge them more easily. Food, people, armaments, and material could get safely across the Atlantic, Sumner said.
The war probably would have gone on years longer without that knowledge, he added. Turing’s crucial work stayed top secret until the late 1970s. “I mean, there is wartime secrecy and there’s wartime secrecy,” Sumner said. “It’s just one of those enduring mysteries as to why it was kept so quiet for so long.”
The Turing Test
After the war, Turing taught math at the University of Manchester, where he had access to the Ferranti Mark I, one of the few computers in the country. He began posing the question whether machines could think. The response from different experts tended to be no, because thought was defined simply as something that humans could do and machines couldn’t.
Turing found the criticism a circular argument, Sumner said. So he sought an alternative way to define thinking for a machine and developed the Turing Test. His idea was to put a human and a machine behind a screen. A judge then has a conversation with both and if he can’t work out which is which, the machine has passed the test.
Most people online today are familiar with a reverse version of the test to distinguish humans from bots. The CAPTCHA test displaying squashed letters actually stands for “Completely Automated Public Turing test to tell Computers and Humans Apart.”
While the original Turing test wasn’t part of a research program and didn’t represent the birth of artificial intelligence, it was a big inspiration to the field, Sumner said. “There was somebody who stepped up and wrote this paper that said I see no particular reason why machines couldn’t be made to think.”
Turing was homosexual when it was still a crime in Britain. In 1952 he reported a burglary he suspected was done by someone who knew the young man he’d been with, Sumner said. But the police were more interested in that relationship than the burglary. When pressed, Turing told the truth.
“He was probably trying to show the system its own stupidity,” Sumner said. Facing prosecution, Turing had a choice: go to jail or a year of hormone “treatment.” He chose the latter, which was essentially chemical castration. The Cold War brought another blow. His criminal status meant losing security clearance.
In 1954, a year after he’d stopped taking the hormones, Turing laced an apple with cyanide he’d synthesized and bit into it. The apple was never tested and his mother thought he'd accidentally licked his fingers, but his death is generally accepted as suicide. Biographer Andrew Hodges theorized that Turing deliberately set it up to gave his mother plausible deniability.
Prime Minister Gordon Brown apologized in 2009 for Turing’s prosecution: “n 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.” However, he wasn’t officially pardoned.
Near the end of his life, Turing focused his attention on the origins of form and shape in living creatures, a process that came to be known as morphogenesis. He wanted to understand how symmetrical cells grew into non-symmetrical arrangements of arms and legs and heads.
He was trying to model that shape development using the Ferranti Mark 1 computer, Sumner explained, but the model was very complex. After Turing’s death, one of his students discovered those papers in his office and protected them. That research is on display for most of the year as part of the Manchester Museum's "Alan Turing and Life’s Enigma" exhibit.
Sumner said he hopes young people who come to the museum discover that there are useful connections to be made in all areas of human thought. By the standards of his time, Turing was more interdisciplinary than most around him, Sumner added. "He was somebody who saw connections in places where most people didn't." And for that and his many other accomplishments, he will be remembered.