> Shannon makes no apologies. “I’ve always pursued my interests without much regard for final value or value to the world,” he said cheerfully. “I’ve spent lots of time on totally useless things.” > The definition of information set forth in Shannon’s 1948 paper is crucial to his theory of communication. Sidestepping questions about meaning (which he has stressed that his theory “can’t and wasn’t intended to address”), Shannon demonstrated that information is a measurable commodity. The amount of information in a given message, he showed, is determined by the probability that—out of all the messages that could be sent—that particular message would be selected. > He defined the overall potential for information in a system as its “entropy,” which in thermodynamics denotes the randomness—or “shuffledness,” as one physicist has put it—of a system. (The great mathematician and computer theoretician John von Neumann persuaded Shannon to use the word entropy. The fact that no one knows what entropy really is, von Neumann argued, would give Shannon an edge in debates over information theory.)