Soap film

A soap film is a natural minimal surface form, as opposed to the mathematical minimal surface. The natural minimal surface form has helical edges. The mathematical minimal surface form has straight edges. This in turn means they have different surface forms, since one surface extends between helical edges, and the other extends between straight edges.

This fact was overlooked by mathematicians for over 150 years because they used thin wire frames within which to suspend their soap-film surfaces, and so could not detect the helical edge of the soap-film.

See also soap bubble.