A “30 Day Song Challenge” blurb isn’t enough to — isn’t the right place for — describing my love and awe for Arcade Fire, which is arguably the greatest rock band in the world right now. Not only is their music gorgeous, complex, inventive, and yet still populist, it is also relevant, in the best sense of the word. They make music about something, not just love, sex, and revenge, like most bands you find of pop and rock radio; they create work that deals with politics, war, sprawl, ennui, hope, and want. They are the heirs of Bob Dylan, Joni Mitchell, and REM. And they’ve probably recorded 10 or 15 songs for the ages, but the one the gets me in the gut is the great anti-war anthem “Intervention,” from Neon Bible. The first video is a fan-made video that uses clips from The Battleship Potemkin and the second is the band performing live in Paris.