Phenomena involving surface tension are extremely complex and have applications in our everyday lives, and researchers are tackling the complicated mathematics behind the physics.

But soap has a lower surface tension, so there is a difference in surface tension between the areas of high and low soap concentration. This drags the water back into the film.

Liquid flows inwards because of effects of gravity and surface tension By RUSS SWAN FOR MAILONLINE Published: 19:01 EDT, 24 November 2015 | Updated: 02:57 EDT, 25 November 2015 ...