Surface tension of bulky colloids, capillarity under gravity and the microscopic origin of the Kardar-Parisi-Zhang equation

Experimental measurements of the surface tension of colloidal interfaces have long been in conflict with computer simulations. In this work we show that the surface tension of colloids as measured by surface fluctuations picks up a gravity dependent contribution which removes the discrepancy. The presence of this term puts a strong constraint on the structure of the interface which allows one to identify corrections to the fundamental equation of equilibrium capillarity and deduce bottom-up the microscopic origin of a growth model with close relation to the Kardar-Parisi-Zhang equation.