When technology makes knowledge globally available, reshaping the economics of buying and selling it becomes crucial (Image: Louie Psihoyos/Science Faction/Corbis)

TEN years ago, a piece of software called Napster taught us that scarcity is no longer a law of nature. The physics of our universe would allow everyone with access to a networked computer to enjoy, for free, every song, every film, every book, every piece of research, every computer program, every last thing that could be made out of digital ones and zeros. The question became not, will nature allow it, but will our legal and economic system ever …