White Holes And Kitchen Sinks

Turn on your kitchen tap and the steady stream of water will spread out into a thin circular disc when it hits the sink. This disc has an unusual property: it is surrounded by a circular “lip”, where the height of the water changes suddenly.

This so-called hydraulic jump has puzzled physicists for at least a hundred years (John Strutt, otherwise known as Lord Rayleigh, published the first mathematical description of the phenomenon in 1914). These kinds of hydrodynamic problems are notoriously difficult to tackle.