Turing, Alan M

What is known today as the Turing machine model captures the character of everyday computation. On the one hand, Alan Turing's design for a universal machine adumbrated the stored-program computer—the “wheel” of the impending computer revolution and of the new information age. On the other hand, he described the unsolvable “halting problem” of this machine: there is an “incomputability,” observable by us, but not by the machine. Turing seems to have seen still a role for human intelligence, even in today's computationally and socially complex world. And he gave us the mathematics to put the failures of mathematics into context. As for the computers on our desks, Turing proclaimed throughout his later career the complementary roles of computing machine and human being.