Flocks of birds and schools of fish swarm in complicated collective motions, but groups of non-living components can move collectively, too. In this Lutetium Project video, we learn about grains that, when vibrated, self-propel and form complex collective motions similar to those seen in groups of living organisms.
A key feature of the grains is their lack of symmetry. To be self-propelling, they must have a well-defined orientation, defined by a different front and back. The grains also have the freedom to move in a direction that is not the same as the direction they’re oriented in. This allows the grains to rotate, which enables them to perform the large-scale motions seen in the experiments. (Video and image credit: The Lutetium Project; research credit: G. Briand et al.)