Cell movements in two-dimensional soap froth

We report the measurements of cell motions in two-dimensional soap froth. The motion is random with large fast movements caused mainly by the side-switching T1 topological transitions during the coarsening of the froth. However, the motion is localized such that there are obvious movements in some confined regions involved in the transitions while it can be motionless elsewhere. The displacement of cell center of mass can be large compared to the cell size if the cell does not survive to later times or contains no (persistent) area that has not been swept by soap film boundaries. However, the displacement is small for cell that survives to the latest time.