Cosmology, Particle Physics, and Superfluid 3he

Many direct parallels connect superfluid 3 He with the field theories describing the physical vacuum, gauge fields and elementary fermions. Superfluid 3 He exhibits a variety of topological defects which can be detected with single-defect sensitivity. Modern scenarios of defect-mediated baryogenesis can be simulated by the interaction of the 3 He vortices and domain walls with fermionic quasiparticles. Formation of defects in a symmetry-breaking phase transition in the early Universe , which could be responsible for large-scale structure formation and for microwave-background anisotropy, also may be modelled in the laboratory. This is supported by the recent observation of vortex formation in neutron-irradiated 3 He-B where the " primordial fireball " is formed in an exothermic nuclear reaction.