Elusive Signs: Bruce Nauman Works with Light is one of those art exhibitions you will want to spend hours in, and you will not be able to, because it will give you a headache. Both impulses are right on: The seminal artist Bruce Nauman's neon works from the 1960s to the 1980s, including the masterpiece One Hundred Live and Die and the parallelogram-shaped room with green light that makes you look like death, are gorgeous, rich, and agonizing. No pleasure without pain. (Henry Art Gallery, 15th Ave NE and NE 41st St, 543-2280. 11 am—5 pm, $10 general, $6 seniors, students free.)