Weak synchronization and macroscopic collective oscillation in dense bacterial suspensions

This real time video uncovers a spectacular form of biological collective motion: Millions of motile cells in dense bacterial suspensions can self-organize into highly robust collective oscillatory motion, while individuals move in an erratic manner. Here two silicone oil tracers appeared as dark spots near the center of field of view, and they underwent synchronized oscillation in elliptical trajectories, revealing the hidden order in bacterial collective motion. See: Chen et al. Nature (2017) doi:10.1038/nature20817.