Located in the cavernous, semicircular structure behind the Palace of Fine Arts rotunda (plans are afoot, however, to move to a larger space on the Embarcadero in coming years), this innovative museum of science, art and human perception has served as a model for similar science museums around the world since its opening in 1969. The Exploratorium's creator, physicist Frank Oppenheimer, maintained a novel philosophy that a museum can best teach science through hands-on participation.The museum boasts more than 650 exhibits in physics, electricity, life sciences, thermodynamics, weather, light, psychology, linguistics, sense perception and a host of other subjects. In-structions and explanations accompany each exhibit, and staff members are available to answer questions. Among the most popular exhibits are the miniature tornado demonstration; the photosensitive Shadow Box, where people's shadows are temporarily recorded on a wall; and the distorted room, where visitors can enter an optical illusion. An additional ticket is needed to enter the soundproof, pitch-black Tactile Dome, a multilevel crawl chamber through which visitors must find their way only by sense of touch (reservations suggested; 415-561-0362). New exhibits are continually being developed in the extensive workshops adjacent to the main floor, in full view of visitors.