Like Montreal’s Godspeed You Black Emperor! or Reykjavik’s Sigur Ros, Austin’s Explosions are a prog-rock group whose music feels less like a requiem for the world than a hopeful meditation on it. The instrumental Earth begins with the repetition of a lone guitar note, then builds into ringing, elongated rock-band crescendos, as sumptuous melodies rise and fall, generally in slow-motion waltz time. It seems like ideal film-soundtrack music, except that its gargantuan beauty would probably overwhelm any image you’d match it to. SING FOR ME On Desert Farmers (Bar/None), singer Hannah Marcus teams with Godspeed! associates, moving the band’s cathedral of sound into a chapel for a set of odd folk songs.