What makes such information so thrilling is that we think of music as a mirror: To love a song is to identify with it; to love an artist is to declare that his or her view of the world resonates with our own. And just as we can learn a lot about our friends by scrolling through their mp3 libraries, so too could someone analyze, say, the last 30 years of recorded music and tell a new kind of story about our culture as a whole.
