Yangjian Cai

A candle flame flickers in a draft but doesn't go out — the tongue of fire briefly changes shape and then returns. Optical skyrmions behave much the same way — tiny vortices in a light beam, reminiscent of swirling eddies. Until recently, they were created only in the perfect, smooth light of a laser.

Light from an ordinary bulb seems utterly chaotic: its waves oscillate out of sync, like a crowd where everyone walks in their own direction. Such light is called incoherent. For a long time, it was believed that elegant topological structures (knots, rings, links) could only be created in coherent laser light, where all waves march in step.