The shards of broken symmetry

The breaking of symmetry in superfluid helium-3 (He-3) and the formation of defects is used to model the dynamics of cosmological phase transitions. Superfluid He-3 is heated and rapidly cooled to make it non-superfluid. Below the critical temperature, the symmetry of He-3 is broken. A gradient in the phase produces a flow pattern whose energy defines the superfluid analogues of cosmic strings, vortex lines. Superfluids are a good medium for studying the defects caused by symmetry breaking.