Knots made in a weird quantum fluid can last forever

By manipulating a quantum fluid, researchers could form liquid knots that never unravel. These could help us shed light on odd quantum objects from the dawn of the universe.

When tiny whirlpools called vortices form in a fluid, they can make loops that can then be knotted like a loop of string. But while a string can form knots that won’t unravel without the help of scissors, knotted vortices in a fluid break free more easily. They can explode into a diffuse swarm of…