Superfluid analogies of cosmological phenomena

In a modern viewpoint relativistic quantum field theory is an emergent phenomenon arising in the low-energy corner of the physical fermionic vacuum - the medium, whose nature remains unknown. The same phenomenon occurs in condensed matter systems: In the extreme limit of low-energy condensed matter systems of special universality class acquire all the symmetries, which we know today in high-energy physics: Lorentz invariance, gauge invariance, general covariance, etc. The chiral fermions as well as gauge bosons and gravity field arise as fermionic and bosonic collective modes of the system. Inhomogeneous states of the condensed matter ground state - vacuum - induce nontrivial effective metrics of the space, where the free quasiparticles move along geodesics. This conceptual similarity between condensed matter and the quantum vacuum allows us to simulate many phenomena in high-energy physics and cosmology, including the axial anomaly, baryoproduction and magnetogenesis, event horizon and Hawking radiation, cosmological constant and rotating vacuum, etc., probing these phenomena in ultra-low-temperature superfluid helium, atomic Bose condensates and superconductors. Some of the experiments have been already conducted. (C) 2001 Elsevier Science B.V. All rights reserved.