CARSTEN HÖLLER’S five silvery slides in Tate Modern’s massive Turbine Hall in London are elegant sculptures that spiral down like giant serpents from the gallery floors, curling and twisting their metallic bodies before reaching the ground with open mouths. They are roofed with transparent acrylic plastic, allowing glimpses of people sliding down. And everyone in the hall can certainly hear them screaming—with excitement, perhaps with fright, and no doubt also with joy. Groups of enthusiasts linger in the arrival area. The ride from the top level, nearly 90 feet high, is terrifyingly fast—the tube itself is 182 feet long and slants 30 degrees downward—but when travelers shoot out onto the floor, they can’t keep from smiling; some of them laugh hysterically.