  This presentation reviews an approach to nuclear many-body systems based on
the spontaneously broken chiral symmetry of low-energy QCD. In the low-energy
limit, for energies and momenta small compared to a characteristic symmetry
breaking scale of order 1 GeV, QCD is realized as an effective field theory of
Goldstone bosons (pions) coupled to heavy fermionic sources (nucleons). Nuclear
forces at long and intermediate distance scales result from a systematic
hierarchy of one- and two-pion exchange processes in combination with Pauli
blocking effects in the nuclear medium. Short distance dynamics, not resolved
at the wavelengths corresponding to typical nuclear Fermi momenta, are
introduced as contact interactions between nucleons. Apart from a set of
low-energy constants associated with these contact terms, the parameters of
this theory are entirely determined by pion properties and low-energy
pion-nucleon scattering observables. This framework (in-medium chiral
perturbation theory) can provide a realistic description of both
isospin-symmetric nuclear matter and neutron matter. The importance of
three-body forces is emphasized, and the role of explicit Delta(1232)-isobar
degrees of freedom is investigated in detail. Nuclear chiral thermodynamics is
developed and a calculation of the nuclear phase diagram is performed. This
includes a successful description of the first-order phase transition from a
nuclear Fermi liquid to an interacting Fermi gas and the coexistence of these
phases below a critical temperature T_c. Density functional methods for finite
nuclei based on this approach are also discussed. Effective interactions, their
density dependence and connections to Landau Fermi liquid theory are outlined.
Finally, the density and temperature dependence of the chiral (quark)
condensate is investigated.
