At “Lifes,” a sundry and symphonic group show at the Hammer Museum in Los Angeles, a string of performances, readings, songs, and a “tuning meditation”—by the great Pauline Oliveros—ebb and flow throughout two galleries as part of an hourly cycle, shifting the vibe as if for the sake of it. The quicksilver approach of the exhibition, which numbers more than fifty participants and runs through May 8, puckishly defies the expectations of a museum to fossilize and dignify its objects on view, to bestow a certain, sacred seriousness. Nothing could be less grave, and more puzzling to pin down, than