Besides this he refreshed his youthful
interest in quantum physics, studying the problem of wave-function
reduction in quantum mechanics, with a hint that he was considering
a non-linear mechanism for it. He took a new interest in the
representation of elementary particles by spinors, and in relativity
theory.
A factor in his life unknown to most around him was that he had
also continued to work for GCHQ, the post-war successor to Bletchley
Park, on the basis of a personal connection with Alexander, now its
director. But since 1948, the conditions of the Cold War, and the
alliance with the United States, meant that known homosexuals had
become ineligible for security clearance. Turing, now therefore
excluded, spoke bitterly of this to his onetime wartime colleague,
now MI6 engineer Donald Bayley, but to no other personal friends.
State security also seems the likely cause of what he described as
another intense crisis in March 1953, involving police searching for
a visiting Norwegian who had come to see him. Concern over the
foreign contacts of one acquainted with state secrets was
understandable, and his holiday in Greece in 1953 could not have
been calculated to calm the nerves of security officers.
Although unable to tell his friends about questions of official
secrecy, in other ways he actively sought much greater intimacy of
expression with them and with a Jungian therapist. Eccentric,
solitary, gloomy, vivacious, resigned, angry, eager, dissatisfied —
these had always been his ever-varying characteristics, and despite
the strength that he showed the world in coping with outrageous
fortune, no-one could safely have predicted his future course.
He was found by his cleaner when she came in on 8 June 1954. He
had died the day before of cyanide poisoning, a half-eaten apple
beside his bed. His mother believed he had accidentally ingested
cyanide from his fingers after an amateur chemistry experiment, but
it is more credible that he had successfully contrived his death to
allow her alone to believe this. The coroner's verdict was suicide.
