title: Young's equation revisited.
abstract: Young's construction for a contact angle at a three-phase intersection forms the basis of all fields of science that involve wetting and capillary action. We find compelling evidence from recent experimental results on the deformation of a soft solid at the contact line, and displacement of an elastic wire immersed in a liquid, that Young's equation can only be interpreted by surface energies, and not as a balance of surface tensions. It follows that the a priori variable in finding equilibrium is not the position of the contact line, but the contact angle. This finding provides the explanation for the pinning of a contact line.
authors.affiliation: Technical Research Centre of Finland, Espoo, 02044 VTT, Finland.
authors.forename: Lasse
authors.initials: L
authors.lastname: Makkonen