If the area of the surface is decreased, the overall energy of the system decreases, so reduction of surface area is a spontaneous process. The soap bubbles are analogous to the grains, and the surfac...If the area of the surface is decreased, the overall energy of the system decreases, so reduction of surface area is a spontaneous process. The soap bubbles are analogous to the grains, and the surfaces of the bubbles are analogous to the grain boundaries. Compare the photographs of the soap bubbles with the micrograph of a polycrystalline material that has been etched to reveal the grain boundaries.
