Turing, Computing and Communication

This essay is a slightly edited transcription of a lecture given in 1997 in King’s College, Cambridge, where Alan Turing had been a Fellow. The lecture was part of a meeting to celebrate the 60th anniversary of the publication of Turing’s paper On computable numbers, with an application to the Entscheidungsproblem, published in the Proceedings of the London Mathematical Society in 1937.