In 1936, a year after becoming a fellow at King's College in Cambridge, Alan Turing wrote a proof showing there is no solution to Hilbert's Entscheidunsproblem (Undecidability Problem). Simply stated, Turing proved that no logical system can be both consistent and complete or there are some problems who's solutions are unknowable. He gained this insight through posing a thought experiment where a theoretical device, using a set of instructions, was capable of performing algorithms on an input set encoded on an infinitely long piece of tape. As a consequence Turing also proved any of these Turing machines where capable of being programmed to perform the functions of any other Turing machine. The ideas in his paper were a theory of computability and the beginning of modern computer science.
Instructions for a portrait in 15 equal parts.