Cluster persistence: A discriminating probe of soap froth dynamics

The persistent decay of bubble clusters in coarsening two-dimensional soap froths is measured experimentally as a function of cluster volume fraction. A dramatically stronger decay is observed in comparison to soap froth mode ls and to measurements and calculations of persistence in other systems. Th e fraction of individual bubbles that contain any persistent area also deca ys, implying significant bubble motion and suggesting that T1 processes pla y an important role in froth persistence.