Thanks for the book reference.
I want to set aside the question of an apology for the moment, and talk about some interesting details. The first is that I don’t think the conviction for homosexual behavior in 1952 had much effect on Alan Turing’s intellectual work, most of which was going on in university and did not depend upon his having security clearance. So the idea that the conviction significantly affected his career is doubtful.
Here’s some information about what he was up to after the war. Following this I want to say something about why he lost his security clearance.
http://www.thocp.net/biographies/turing_alan.html
(By 1948 Newman was the professor of mathematics at the University of Manchester and offered Turing a readership there. Turing resigned from the National Physical Laboratory to take up the post in Manchester. Newman writes in [12] that in Manchester:-
... 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 published Computing machinery and intelligence in Mind. It is another remarkable work from his brilliantly inventive mind which seemed to foresee the questions which would arise as computers developed. He studied problems which today lie at the heart of artificial intelligence. It was in this 1950 paper that he proposed the Turing Test which is still today the test people apply in attempting to answer whether a computer can be intelligent.
Turing did not forget about questions of decidability which had been the starting point for his brilliant mathematical publications. One of the main problems in the theory of group presentations was the question: given any word in a finitely presented groups is there an algorithm to decide if the word is equal to the identity. Post had proved that for semigroups no such algorithm exits. Turing though at first that he had proved the same result for groups but, just before giving a seminar on his proof, he discovered an error. He was able to rescue from his faulty proof the fact that there was a cancellative semigroup with insoluble word problem and he published this result in 1950. Boone used the ideas from this paper by Turing to prove the existence of a group with insoluble word problem in 1957.
Turing was elected a Fellow of the Royal Society of London in 1951, mainly for his work on Turing machines in 1936. By 1951 he was working on the application of mathematical theory to biological forms. In 1952 he published the first part of his theoretical study of morphogenesis, the development of pattern and form in living organisms.
Turing was arrested for violation of British homosexuality statutes in 1952 when he reported to the police details of a homosexual affair. He had gone to the police because he had been threatened with blackmail. He was tried as a homosexual on 31 March 1952, offering no defence other than that he saw no wrong in his actions. Found guilty he was given the alternatives of prison or oestrogen injections for a year. He accepted the latter and returned to a wide range of academic pursuits.
Not only did he press forward with further study of morphogenesis, but he also worked on new ideas in quantum theory, on the representation of elementary particles by spinors, and on relativity theory. Although he was completely open about his sexuality, he had a further unhappiness which he was forbidden to talk about due to the Official Secrets Act.
The decoding operation at Bletchley Park became the basis for the new decoding and intelligence work at GCHQ. With the cold war this became an important operation and Turing continued to work for GCHQ, although his Manchester colleagues were totally unaware of this. Now after his conviction, his security clearance was withdrawn. Worse than that, security officers were now extremely worried that someone with complete knowledge of the work going on at GCHQ was now labelled a security risk. He had many foreign colleagues, as any academic would, but the police began to investigate his foreign visitors. A holiday which Turing took in Greece in 1953 caused consternation among the security officers.
Turing died of potassium cyanide poisoning while conducting electrolysis experiments. The cyanide was found on a half eaten apple beside him. An inquest concluded that it was self-administered but his mother always maintained that it was an accident. ]
Why did Turing lose his security clearance? I don’t know for sure and I’m not in a position to do the research now but I do think it goes something like this.
The British government was riddled with KGB agents during World War II and the postwar period. These were high profile British citizens, highly educated, and usually homosexual, sometimes quite openly. Four or five of them had been to Cambridge. People like Guy Burgess, Anthony Blunt, Kim Philby sent hundreds of British agents and contacts in Eastern Europe to their deaths, they helped the Soviets get nuclear weapons, they informed the Soviets about decoding efforts in which Turing had been involved, some of them are said to have played an essential role in initiating the Berlin Blockade. Several of these people defected to the Soviet Union in the late 40s and early 50s. Others remained under cover for longer. But surely the British government knew they probably were still there. I believe some of John Le Carres novels are about this.
Anybody homosexual could be blackmailed by the KGB, given the laws in place in the UK. Alan Turing had studied at Cambridge, he had been a left-winger, and he probably had known some these spies personally and moved
in the same circles. And he was very openly homosexual, another reason he would have known them. He fit the profile of the spies, he was vulnerable to blackmail, he had a penchant for traveling outside the UK, probably to have homosexual relationships with young men (something he continued to do after the estrogen injections ended– they went on for a year– which scared the BeJesus out of the British government, as mentioned above). The people who lifted Turing’s security probably did not much like the law that he had been convicted of breaking, and it is unlikely that they cared about Turing's homosexuality per se. But under the circumstances, the world close to the brink of World War III, I believe they judged that Turing was too vulnerable and potentially too dangerous to have continued access to top-secret British decoding efforts.
