“With no object, no image and no focus,” the California artist James Turrell asks, “what are you looking at?” A pioneer of the California Light and Space movement, which began in the 1960s, Turrell has long evaded classification. He grew up in Los Angeles with Quaker parents, and as a young man learned to fly airplanes, leaned into the hippy movement, and was a conscientious objector during the Vietnam War. In college, Turrell studied perceptual psychology, training he brought to his first Santa Monica studio, where Robert Irwin, Mary Corse, and Doug Wheeler were frequent visitors. In “Elemental” he experiments with pulsating transitions of color, the minute changes mimicking the breathing patterns of animals, which are projected onto the gallery’s convex walls. The show marks Turrell’s 20th anniversary with Pace. —Elena Clavarino