Some bands turn into shorthand for a certain sound or style, and Pink Floyd belongs among that elite group. The very name connotes something specific: an elastic, echoing, mind-bending sound that evokes the chasms of space. Pink Floyd grounded that limitless sound with exacting explorations of mundane matters of ego, mind, memory, and heart, touching upon madness, alienation, narcissism, and society on their concept albums of the '70s. Of these concept albums, Dark Side of the Moon resonated strongest, earning new audiences year after year, decade after decade, and its longevity makes sense. That 1973 album distilled the wild psychedelia of their early years -- that brief, heady period when they were fronted by Syd Barrett -- into a slow, sculpted, widescreen epic masterminded by Roger Waters.