A Mind at Play: How Claude Shannon Invented the Information Age

by Jimmy Soni

communication is a war against noise. Noise is interference between telephone wires, or static that interrupts a radio transmission, or a telegraph signal corrupted by failing insulation and decaying on its way across an ocean. It is the randomness that creeps into our conversations, accidentally or deliberately, and blocks our understanding.

The real measure of information is not in the symbols we send—it’s in the symbols we could have sent, but did not. To send a message is to make a selection from a pool of possible symbols, and “at each selection there are eliminated all of the other symbols which might have been chosen.” To choose is to kill off alternatives. We see this most clearly, Hartley observed, in the cases in which messages happen to bear meaning. “For example, in the sentence, ‘Apples are red,’ the first word eliminated other kinds of fruit and all other objects in general. The second directs attention to some property or condition of apples, and the third eliminates other possible colors.” This rolling process of elimination holds true for any message. The information value of a symbol depends on the number of alternatives that were killed off in its choosing. Symbols from large vocabularies bear more information than symbols from small ones. Information measures freedom of choice.

It turns out that some of the most childish questions about the world—“Why don’t apples fall upwards?”—are also the most scientifically productive. If there is a pantheon of such absurd and revealing questions, it ought to include a space for Shannon’s: “Why doesn’t anyone say XFOML RXKHRJFFJUJ?” Investigating that question made clear that our “freedom of speech” is mostly an illusion: it comes from an impoverished understanding of freedom. Freer communicators than us—free, of course, in the sense of uncertainty and information—would say XFOML RXKHRJFFJUJ. But in reality, the vast bulk of possible messages have already been eliminated for us before we utter a word or write a line. Or, to alter just slightly one of the fortuitous sequences that emerged by chance on Shannon’s notepad: THE LINE MESSAGE HAD [TO] BE THESE.

codebreaking remained possible, and remains so, because every message runs up against a basic reality of human communication. It always involves redundancy; to communicate is to make oneself predictable.

Here Shannon completed the reimagining that began with his thesis and his switches eleven years earlier. 1’s and 0’s could enact the entirety of logic. 1’s and 0’s stood for the fundamental nature of information, an equal choice from a set of two.

And now it was evident that any message could be sent flawlessly—we could communicate anything of any complexity to anyone at any distance—provided it was translated into 1’s and 0’s. Logic is digital. Information is digital.

“bits are the universal interface.”

The chess machine is an ideal one to start with, since: (1) the problem is sharply defined both in allowed operations (the moves) and in the ultimate goal (checkmate); (2) it is neither so simple as to be trivial nor too difficult for satisfactory solution; (3) chess is generally considered to require “thinking” for skillful play; a solution of this problem will force us either to admit the possibility of a mechanized thinking or to further restrict our concept of “thinking”; (4) the discrete structure of chess fits well into the digital nature of modern computers.

a genius is simply someone who is usefully irritated.