You’re taught never to touch the art, but in this little one-room installation by British artist Anthony McCall, you couldn’t touch it even if you wanted to. McCall’s light sculpture looks solid: in a pitch black room filled with smoke, the lines he creates in the space look like grey marble walls. But reach out and your hand drops right though. Duh, it’s light, bozo. But that’s all part of his trick, as you stand in the middle of lines, you feel trapped in solid matter. His work dissects and bisects the space. It’s solidity out of nothing, or at least the illusion of it. And it’s free. Whaaaaat?! If you only see one exhibition this week, make it this one.