The decade of the 2000s is marked by many indelible images. Among them: black smoke billowing from the World Trade Center's Twin Towers just moments after being struck by airplanes; young people, wearing ear buds, turning the dial on their iPods and listening to their favorite downloaded tunes; traumatized people wandering through scenes of utter devastation on beaches in Thailand and Sri Lanka after a massive tsunami; two robotic rovers crawling...