London's Hayward Gallery will soon be hosting an exhibition of invisible art. It's the kind of art where you basically have to take the artist's word for it that there's something there.
Included will be works such as Warhol's Invisible Sculpture, "which consists of an empty plinth, on which he had once briefly stepped." Also, 1000 Hours of Staring, which is "a blank piece of paper at which artist Tom Friedman has stared repeatedly over the space of five years."
I wonder how copyright pertains to invisible art. Can you sue someone for copying your blank canvas? Link: telegraph.co.uk.