Look closely at the pattern on the wheel. Start spinning it. Slowly increase the spinning speed. What are you seeing? Experiment by rotating the disc with various angular velocities in both directions.
How does it work
A slowly spinning wheel looks like it has a circle moving along the circumference. When the speed is high, black-and-white details blur into grey. The eye cannot catch up and the images transmitted to the brain are indistinct. In the centre of the wheel the linear speed is the smallest. That’s why we can distinguish black lines against the white background in this region.
French artist Marcel Duchamp (1887–1968) used the stereoscopy (the illusion of depth) in 1935 in spinning cardboard wheels called Rotoreliefs). Two different designs of his are presented in our exhibition as ‘Crater’ and ‘Colourful crater’.