The closest thing to a unified theory of information comes in the 1940s from Claude Shannon, who is the hero of Gleick's book. An Isaac Newton figure, Shannon deployed mathematics to capture information just as Newton turned to mathematics to capture the essential nature of motion. The inventor of the "bit"—the metric Shannon introduced to quantify information—realized that information is related at its core to order and uncertainty, and therefore to entropy. Indeed, Shannon introduced the deeply confusing idea that information, fundamentally, "is entropy."
That idea is extremely hard to explain, but here is my effort. A tossed coin can land one of two ways, heads or tails. Its outcome is uncertain, and the coin's state is unordered, or entropic. To Shannon, that uncertainty is the informational capacity of the coin: one bit, or two possible outcomes. Moreover, the uncertainty created by multiple bits can code for extraordinarily complex messages, Shannon showed, and those messages can be communicated across giant distances, given the right kind of channels. Shannon's work lies behind the text you're reading right now, which was reduced to bits, sent across some distance, and recreated on the other side.
After reaching the mid-20th century, Gleick turns from history to devote roughly one-half of his book to a mind-bending exploration of theory, which I found the highlight of his undertaking. Here Gleick considers at length, for example, Richard Dawkins' idea that humans might be best described as little more than information carriers. This follows if we believe Dawkins' idea that our bodies are containers for DNA, which itself is just a code and a storage format, from an informational point of view. That's what a scientist means by the word becoming flesh.
Gleick spans so many areas as he delves into efforts to understand and wield information down the centuries—from the invention of Morse code and the OED, through genetics, to the idea of memes and psychology—that at times the chapters, while linked thematically, can resemble stand-alone essays. For example, he includes a debate over whether black holes can destroy information. The question is unquestionably cool, but difficult, for this limited mind, to connect with anything else. It's also quite hard to understand if you're not already familiar with the mathematical properties of time and space.
I couldn't help wishing, though, that Gleick had made it to the economic study of information, which he alludes to briefly in the introduction. Granted, Gleick is a science writer, not a social-science writer. But his book ends with a coda ("A Flood") on the times we live in, and it is here that getting a feel for the economic principles of information would have helped critically. Indeed, to try and understand the Internet or firms like Google, as Gleick does in the end, informational theorists like Joesph Stiglitz and Friedrich Hayek may matter as much as Shannon. * Take Hayek's idea that the superior performance of markets over socialist planned economies had nothing to do with actual efficiencies (competition is wasteful), but can be chalked up to superior use of information (prices are a form of information). It's a perfect example of information as the greater shaper of human history—in this case, arguably winning the Cold War on behalf of the West. Trying to link the economic principles of information with its scientific properties would have been a great service.
Still, the web Gleick has woven is a rare one, a whole that envelops and exceeds its many parts, which certainly suits his topic. His contribution—too easily underrated in a work that synthesizes the ideas of others—lies in linking fields of science that aren't connected in a formal sense. By the close of the book you cannot think of information as you might have before. It has become, quite palpably, something different than almost anything we encounter: resistant to decay and capable of perfect self-reproduction. It outlasts the organic beings who create it, and, by replication, the inorganic mediums used to store it. Gleick's deepest subject, it occurred to me as I finished reading, is immortality. Perhaps it should not come as such a great surprise that The Information—not unlike other science books that tackle big human quests for understanding—at times bears more than a passing resemblance to a spiritual text. For "In the beginning," as Gleick reminds us in the introduction, "was the word."
Correction, March 29, 2011: This article originally misspelled the first name of Friedrich Hayek. ( Return to the corrected sentence.)