Felix Kahlhoefer

A detector filled with superfluid helium-4 is like a perfectly still lake. The liquid doesn't slosh or bubble: it's frozen in a single quantum state. An invisible guest, a dark matter particle, flies through it. It doesn't shine or leave a track. But sometimes it nudges a helium nucleus.

Boiling water in a pot is a good place to start. Bubbles of steam rise, pop, and the surface settles down. Something similar might have happened in the first moments of the universe's life with a special field filling space: bubbles of a new phase inflated and collided, like islands of steam in liquid.