A Mind at Play INTRODUCTION The thin, white-haired man had spent hours wandering in and out of meetings at the International Information Theory Symposium in Brighton, England, before the rumors of his identity began to proliferate. At first the autograph seekers came in a trickle, and then they clogged hallways in long lines. At the evening banquet, the symposium''s chairman took the microphone to announce that "one of the greatest scientific minds of our time" was in attendance and would share a few words--but once he arrived onstage, the thin, white-haired man could not make himself heard over the peals of applause. And then finally, when the noise had died down: "This is--ridiculous!" Lacking more to say, he removed three balls from his pocket and began to juggle. After it was over, someone asked the chairman to put into perspective what had just happened. "It was," he said, "as if Newton had showed up at a physics conference. It was 1985, and the juggler''s work was long over, and just beginning. It had been nearly four decades since Claude Elwood Shannon published "the Magna Carta of the Information Age"--invented, in a single stroke, the idea of information.
And yet the world his idea had made possible was only just coming into being. Now we live immersed in that world, and every email we have ever sent, every DVD and sound file we have ever played, and every Web page we have ever loaded bears a debt to Claude Shannon. It was a debt he was never especially keen to collect. He was a man immune to scientific fashion and insulated from opinion of all kinds, on all subjects, even himself, especially himself; a man of closed doors and long silences, who thought his best thoughts in spartan bachelor apartments and empty office buildings. A colleague called Shannon''s information theory "a bomb." It was stunning in its scope--he had conceived of a new science nearly from scratch--and stunning in its surprise--he had gone years barely speaking a word of it to anyone. Of course, information existed before Shannon, just as objects had inertia before Newton. But before Shannon, there was precious little sense of information as an idea, a measurable quantity, an object fitted out for hard science.
Before Shannon, information was a telegram, a photograph, a paragraph, a song. After Shannon, information was entirely abstracted into bits. The sender no longer mattered, the intent no longer mattered, the medium no longer mattered, not even the meaning mattered: a phone conversation, a snatch of Morse telegraphy, a page from a detective novel were all brought under a common code. Just as geometers subjected a circle in the sand and the disc of the sun to the same laws, and as physicists subjected the sway of a pendulum and the orbits of the planets to the same laws, Claude Shannon made our world possible by getting at the essence of information. It is a puzzle of his life that someone so skilled at abstracting his way past the tangible world was also so gifted at manipulating it. Shannon was a born tinkerer: a telegraph line rigged from a barbed-wire fence, a makeshift barn elevator, and a private backyard trolley tell the story of his small-town Michigan childhood. And it was as an especially advanced sort of tinkerer that he caught the eye of Vannevar Bush--soon to become the most powerful scientist in America and Shannon''s most influential mentor--who brought him to MIT and charged him with the upkeep of the differential analyzer, an analog computer the size of a room, "a fearsome thing of shafts, gears, strings, and wheels rolling on disks" that happened to be the most advanced thinking machine of its day. Shannon''s study of the electrical switches directing the guts of that mechanical behemoth led him to an insight at the foundation of our digital age: that switches could do far more than control the flow of electricity through circuits--that they could be used to evaluate any logical statement we could think of, could even appear to "decide.
" A series of binary choices--on/off, true/false, 1/0--could, in principle, perform a passable imitation of a brain. That leap, as Walter Isaacson put it, "became the basic concept underlying all digital computers." It was Shannon''s first great feat of abstraction. He was only twenty-one. A career that launched with "possibly the most important, and also the most famous, master''s thesis of the century" brought him into contact and collaboration with thinkers like Bush, Alan Turing, and John von Neumann: all, like Shannon, founders of our era. It brought him into often-reluctant cooperation with the American defense establishment and into arcane work on cryptography, computer-controlled gunnery, and the encrypted transatlantic phone line that connected Roosevelt and Churchill in the midst of world war. And it brought him to Bell Labs, an industrial R&D operation that considered itself less an arm of the phone company than a home for "the operation of genius." "People did very well at Bell Labs," said one of Shannon''s colleagues, "when they did what others thought was impossible.
" Shannon''s choice of the impossible was, he wrote, "an analysis of some of the fundamental properties of general systems for the transmission of intelligence, including telephony, radio, television, telegraphy, etc."--systems that, from a mathematical perspective, appeared to have nothing essential in common until Shannon proved that they had everything essential in common. It would be his second, and greatest, feat of abstraction. Before the publication of his "Mathematical Theory of Communication," scientists could track the movement of electrons in a wire, but the possibility that the very idea they stood for could be measured and manipulated just as objectively would have to wait until it was proved by Shannon. It was summed up in his recognition that all information, no matter the source, the sender, the recipient, or the meaning, could be efficiently represented by a sequence of bits: information''s fundamental unit. Before the "Mathematical Theory of Communication," a century of common sense and engineering trial and error said that noise--the physical world''s tax on our messages--had to be lived with. And yet Shannon proved that noise could be defeated, that information sent from Point A could be received with perfection at Point B, not just often, but essentially always. He gave engineers the conceptual tools to digitize information and send it flawlessly (or, to be precise, with an arbitrarily small amount of error), a result considered hopelessly utopian up until the moment Shannon proved it was not.
Another engineer marveled, "How he got that insight, how he even came to believe such a thing, I don''t know." That insight is embedded in the circuits of our phones, our computers, our satellite TVs, our space probes still tethered to the earth with thin cords of 0''s and 1''s. In 1990, the Voyager 1 probe turned its camera back on Earth from the edge of the solar system, snapped a picture of our planetary home reduced in size to less than a single pixel--to what Carl Sagan called "a mote of dust suspended in a sunbeam"--and transmitted that picture across four billion miles of void. Claude Shannon did not write the code that protected that image from error and distortion, but, some four decades earlier, he had proved that such a code must exist. And so it did. It is part of his legacy; and so is the endless flow of digital information on which the Internet depends, and so is the information omnivory by which we define ourselves as modern. By his early thirties, he was one of the brightest stars of American science, with the media attention and prestigious awards to prove it. Yet, at the height of his brief fame, when his information theory had become the buzz-phrase to explain everything from geology to politics to music, Shannon published a four-paragraph article kindly urging the rest of the world to vacate his "bandwagon.
" Impatient with all but the most gifted, he still knew very little of ambition, or ego, or avarice, or any of the other unsightly drivers of accomplishment. His best ideas waited years for publication, and his interest drifted across problems on a private channel of its own. Having completed his pathbreaking work by the age of thirty-two, he might have spent his remaining decades as a scientific celebrity, a public face of innovation: another Bertrand Russell, or Albert Einstein, or Richard Feynman, or Steve Jobs. Instead, he spent them tinkering. An electronic, maze-solving mouse named Theseus. An Erector Set turtle that walked his house. The first plan for a chess-playing computer, a distant ancestor of IBM''s Deep Blue. The first-ever wearable computer.
A calculator that operated in Roman numerals, code-named THROBAC ("Thrifty Roman-Numeral Backward-Looking Computer"). A fleet of customized unicycles. Years devoted to the scientific study of juggling. And, of course, the Ultimate Machine: a box and a switch, which, when flipped on, produced a whirring of gears and a mechanical hand that emerged from the box, flipped the switc.