A stream of water appears to form a corkscrew shape and even move backwards in this video by science & illusion enthusiast Brusspup. The effect is achieved by playing a 24hz sine wave sound on a speaker, running water past the speaker, and filming the water at 24 frames per second (the effect is not visible to the naked eye). The water appears to move slowly forwards or backwards by raising or lowering the sound frequency.
via Colossal
