Dark Matter Superfluidity
  In this talk I summarize a novel framework that unifies the stunning success
of MOND on galactic scales with the triumph of the $\Lambda$CDM model on
cosmological scales. This is achieved through the rich and well-studied physics
of superfluidity. The dark matter and MOND components have a common origin,
representing different phases of a single underlying substance. In galaxies,
dark matter thermalizes and condenses to form a superfluid phase. The
superfluid phonons couple to baryonic matter particles and mediate a MOND-like
force. This framework naturally distinguishes between galaxies (where MOND is
successful) and galaxy clusters (where MOND is not): dark matter has a higher
temperature in clusters, and hence is in a mixture of superfluid and normal
phase. The rich and well-studied physics of superfluidity leads to a number of
striking observational signatures, which we briefly discuss. Remarkably the
critical temperature and equation of state of the dark matter superfluid are
similar to those of known cold atom systems. Identifying a precise cold atom
analogue would give important insights on the microphysical interactions
underlying DM superfluidity. Tantalizingly, it might open the possibility of
simulating the properties and dynamics of galaxies in laboratory experiments.
