  I give a unified perspective on the properties of a variety of quantum
liquids using the theory of quantum phase transitions. A central role is played
by a zero density quantum critical point which is argued to control the
properties of the dilute gas. An exact renormalization group analysis of such
quantum critical points leads to a computation of the universal properties of
the dilute Bose gas and the spinful Fermi gas near a Feshbach resonance.
