Turing's Cathedral by George Dyson: review While our universe may have popped out of nothing due to what physicists describe as a quantum fluctuation, the origins of the digital universe of 0s and 1s required the US military's desire to be armed with a hydrogen bomb at the beginning of the Cold War and it "had to be squeezed into existence" between simulations of nuclear explosions. Two real-world explosions in 1952 and 1954 confirmed the correctness of those calculations and the indispensable nature of a computer that could be reprogrammed to carry out different tasks, the theory behind which had first been worked out by the British mathematician Alan Turing. Despite its title, Turing doesn't make his much anticipated entrance in Dyson's book until chapter 13, when as a 24-year-old he boards a transatlantic liner bound for New York in September 1936. Turing was to spend the next two years in Princeton working on his PhD, but before leaving Britain he had already finished his seminal paper "On computable numbers." It would, as Dyson points out, "lead the way from logic to machines" as Von Neumann's team turned Turing's theoretical ideas into Maniac. Turing may have been the intellectual visionary, but Dyson's book is about Von Neumann, the chief architect who oversaw the construction of the hardware and software architecture that allowed sequences of code to be stored, recalled and executed. Yet Dyson acknowledges that Maniac was not the first operational stored-programme computer. That was the Small Scale Experimental Machine, developed in June 1948 at Manchester University where Turing was by then based having helped break the German navy's Enigma code during the war as a leading member of Bletchley Park. Turing and Von Neumann were chalk and cheese in everything except their shared interest in computers. Von Neumann always dressed in a suit and spoke with precision; Turing was unkempt and hesitated as if words could not keep up with his thoughts. Von Neumann had an eye for women; Turing's homosexuality would lead to a conviction for gross indecency. Forced to undergo "therapy" with oestrogen injections, he committed suicide in 1954. Faced with the tricky task of balancing technical details with keeping the narrative accessible for the non-computer buff, Dyson ends up probably not giving enough detail to satisfy the aficionado but too much for the lay reader. "Evolution in the digital universe now drives evolution in our universe," he says, "rather than the other way around." Turing, Von Neumann and their colleagues may have let the genie out of the bottle, but Dyson has done the difficult job of reminding us of how much we owe them and how far we have come in such a short time. Manjit Kumar is the author of Quantum (Icon) Turing's Cathedral by George Dyson 401pp, Allen Lane t £23 (PLUS £1.25 p&p) Buy now from Telegraph Books (RRP £25)