What is it about?

We perceive the world selectively and rely on our expectations. We are accustomed to a world of repeating experiences. This upward flowing waterfall counteracts our intuition and questions our perception.

The illusion is created by a stroboscope which is tuned to a slightly different frequency relative to a series of loudspeakers. Single water droplets fall out of nozzles attached to the loudspeakers and seem to be flowing upwards in the light of the stroboscope.