Capillarity is a manifestation of the cohesion of matter due to strong, short-ranged forces between adjacent particles. Examples abound: The curving meniscus in test tubes and the soaking up of liquids by a sponge reflect the balance between the adhesive forces between the walls and liquid and the cohesive forces or surface tension of the liquid. In fluids and other deformable media, capillary forces—a general term that encompasses adhesive and cohesive forces and surface tension—tend to minimize the surface area of a given volume and are responsible for the spherical shape of isolated drops. Although qualitatively straightforward to describe, capillary phenomena have presented numerous challenges to quantitative understanding.
The notion of force was central to the early development of modern physics. The foremost example was the gravitational force, by which large masses attract each other. Capillarity first arose in the history of ideas as an anomaly to the law of...
