As one might expect, the BBC News site has a number of articles related to the Alan Turing Centenary. In particular, it has been publishing a series of essays on Turing’s life and work. I have tried to give a brief overview of these below. (The essays are set up as separate pages, but there is a set of links to all of them at the top of each article.)
The first essay, on “Turing’s Genius”, is by Google’s Vint Cerf, who I have mentioned before in connection with the ACM’s participation in the Turing Centenary, and who is a recipient of the ACM’s Turing Award. (As he mentions in his essay, he also, coincidentally, shares a birthday with Turing: June 23.) He discusses the many ways in which Turing’s original work relates to the technological world we all take for granted today.
The second essay, by Prof. Jack Copeland, University of Canterbury, Christchurch, New Zealand, relates Turing’s involvement in code-breaking at the Government Code and Cypher School at Bletchley Park (also called Station X). It mentions Turing’s personal contribution to breaking the naval version of the German Enigma encryption system, and the Lorenz cipher. These mathematical, cryptanalytic contributions would have been impressive; but Turing also made an enormous contribution to the work of turning Station X into what was, in effect, the world’s first code-breaking factory. He helped develop the bombes, electro-mechanical computers used to break Enigma messages on a production basis, and the Tunny machine, used for the Lorenz cipher. (A project to reconstruct a Tunny machine is underway.) As in many aspects of wartime intelligence, time was of the essence.
The faster the messages could be broken, the fresher the intelligence that they contained, and on at least one occasion an intercepted Enigma message’s English translation was being read at the British Admiralty less than 15 minutes after the Germans had transmitted it.
The third essay, “Alan Turing: The Father of Computing?”, is by Prof. Simon Lavington, author of Alan Turing and His Contemporaries: Building the World’s First Computers. He observes that Turing’s ideas were not always terribly influential in some of the early computer implementations.
It was not until the late 1960s, at a time when computer scientists had started to consider whether programs could be proved correct, that On Computable Numbers came to be widely regarded as the seminal paper in the theory of computation.
On Computable Numbers, with an Application to the Entscheidungsproblem [PDF], Turing’s paper, proved nonetheless to be of immense importance. In it, Turing laid out, for the first time as far as I know, the idea of a theoretical machine that, as demonstrated in his mathematical analysis, could solve any solvable problem.
The fourth essay, by Prof. Noel Sharkey of the University of Sheffield, discusses the Turing Test, proposed by Turing in his 1950 paper, Computing Machinery and Intelligence. That paper begins with a statement of the fundamental problem:
I propose to consider the question, ‘Can machines think ?’ This should begin with definitions of the meaning of the terms ‘machine ‘ and ‘ think ‘.
Turing’s paper was provocative, in part, because he realized how woolly the question, “Can machines think?”, really is There are ongoing discussions of whether the test that Turing proposed is the right one, but it does have the considerable virtue of being realizable in practice.