The problem with tennis and Alan Turing’s solution

“Turing would rather suddenly develop a tremendous passion for some form of activity, or some study, and wish to devote a lot of his time and energy to it. On my first encounter with him at Bletchley Park he was obviously very much fascinated by chess problems. At BP he developed a real delight in playing tennis, and especially enjoyed playing doubles. He was very good up at the net, where his speed and good eye enabled him to make many effective interceptions. However, he was dissatisfied with his success rate: too often he intercepted a return from an opponent, but sent the ball into the net. Applying his remarkable thinking processes to a mundane problem, he reasoned as follows: β€˜The problem is that, when intercepting, one has very little time to plan one’s stroke. The time available is a function of the tautness of the strings of my racquet. Therefore I must loosen the strings.’ And, being Alan Turing, he then carried out the necessary alterations to his racquet himself. At this point my recollection may be coloured by the great distance in time, but I seem to recall Turing turning up for his next game with a racquet somewhat resembling a fishing net. He was absolutely devastating, catching the ball in his racquet and delivering it wherever he choseβ€”but plainly in two distinct operations and, therefore, illegally. He was soon persuaded to revert to a more orthodox racquet!” (Hilton, 2006, pp. 198–199)


Hilton, P. (2006). Living with Fish: Breaking Tunny in the Newmanry and the Testery. In J. B. Copeland (Ed.), Colossus (pp. 189–203). Oxford University Press.