You can often hear that we live in the “information age” which obviously makes information theory relevant not only to understanding cryptography, but also to understanding modern society. First, however, we must be clear on what is meant by the phrase “information age.” To a great extent, the information age and the digital age go hand-in-hand. Some might argue the degree of overlap, but it is definitely the case that without modern computers, the information age would be significantly stifled. Claude Shannon, who’s regarded as the father of information theory, wrote his famous paper, “A Mathematical Theory of Communication,” in 1948—long before digital computers even existed. From one perspective, the information age is marked by the information itself, which has become a primary commodity. Obviously, information has always been of value, but it was historically just a means to a more concrete end.
For example, even prehistoric people required information, such as locations for obtaining food and game. That information was peripheral to the tangible commodity of food. In this example, the food was the goal—the actual commodity. In the information age, the information itself is the commodity. If you reflect on this even briefly, I think you will concur that in modern times information itself is a product. Consider, for example, this book you now hold in your hands. Certainly the paper and ink used was not worth the price of the book. It is the information encoded on the pages that you pay for. In fact, you may have an electronic copy and not actually have purchased any pages and ink at all. If you are reading this book as part of a class, you paid tuition for the class. The commodity you purchased was the information transmitted to you by the professor or instructor (and, of course, augmented by the information in this book). So, clearly, information as a commodity can exist separately from computer technology. The efficient and effective transmission and storage of information, however, requires computer technology.
Still another perspective on the information age is the proliferation of information. Just a few decades ago, news meant a daily paper, or perhaps a 30-minute evening news broadcast. Today news is 24 hours a day on several cable channels and on various websites. In my own childhood, research meant going to the local library and consulting a limited number of publications which were, hopefully, not more than ten years outdated. Now, with the click of a mouse button, you have access to scholarly journals, research web sites, almanacs, dictionaries, encyclopedias—an avalanche of information. So we could view the information age as the age in which most people have ready access to a wide range of information.
Younger readers who have grown up with the Internet and cell phones and who have been absorbed in a sea of instant information may not fully realize how much information has exploded. Once you appreciate the magnitude of the information explosion, the more you can fully appreciate the need for information theory. To give you some perspective on just how much information is being transmitted and consumed in our modern civilization, consider the following facts: As early as 2003, experts estimated that humanity had accumulated a little over 12 exabytes of data during the entire course of human history. Modern media, such as magnetic storage, print, and film, had produced 5 exabytes in just the first two years of the 21st century. In 2009, researchers claim that in a single year, Americans consumed more than 3 zettabytes of information. 1 As of 2013, the World Wide Web is said to hold 4 zettabytes, or 4,000 exabytes, of data.
These incredible scales of data can be daunting to grasp but should give you an idea as to why information theory is so important. It should also clearly demonstrate that whether you measure data by the amount of information we access, or the fact that we value information itself as a commodity, we are truly in the Information Age.