Active matter produces fascinating collective motions from the interactions of many moving objects. Daniel Beller and collaborators describe a new kind of collective motion in the first three-dimensional example of an active nematic material, which shares some key properties with liquid crystals. In work published in the journal Science, the authors showed that topologically neutral defect loops are central to the self-stirring motions of 3D active nematics. The loops continually form, reconnect with one another, and self-annihilate as part of the highly chaotic dynamics.
