Turn off your mind, relax and float . . . off? Up? Out? On their breakthrough album, these Icelanders kicked up sound clouds that seem to stretch across the sky, laced with Jónsi Þór Birgisson's droning, bowed guitar, icy falsetto and melodies so spacey they barely register as tunes. Ágætis byrjun is seriously drifty stuff, ideal for laying perfectly still, going totally blank and imagining every particle in your body gently separating from every other particle.