A Japanese mathematician has come up with what has been called the best illusion of the year by vision scientists. Kokichi Sugihara created a structure of complicated cardboard ramps that that seemed to make balls placed on the structure defy gravity. "From every viewpoint but one the contraption looks like what it really is: a mess of ramps and columns at different angles and eccentricities. But from one spot, the three-dimensional solid becomes ambiguous, and our brains favor the solution that puts the columns at neat right angles, making the ramps seem to be below the platform."