In the main part of this manuscript we present the correlation function des
cription of the polar phase in superfluid He-3 in the bulk in the hydrodyna
mic regime. This is done using the formalism introduced by Mori and Zwanzig
and exploited in the hydrodynamic regime by Forster. The present investiga
tion was triggered by recent NMR experiments on superfluid He-3 in aerogels
of very high porosity which suggested that the superfluid phase found migh
t be different from the A and B phases present in the bulk. It appears from
more microscopic calculations that the polar phase is one of the leading a
lternative candidates. As one of the results, which can only be obtained in
the framework of the projector formalism, we find that the characteristic
contributions in the hydrodynamic equations which guarantee the correct tra
nsformation behavior under rigid rotations are exclusively due to the non-i
nstantaneous reversible contributions from the memory matrix. This result f
or the polar phase contrasts with that for other systems with spontaneously
broken rotational symmetry in real space - which have the same type of con
tributions in the phenomenological hydrodynamic equations - such as nematic
liquid crystals and the superfluid A phase of He-3. In addition to the tru
ly hydrodynamic regime, we study the influence of the magnetic dipole inter
action and of a weak external magnetic field thus including the k = 0 dynam
ics relevant for NMR. For the first time we examine the influence of the pr
esence of the aerogel on the reversible and dissipative macroscopic dynamic
s in the framework of the projector formalism, (C) 1999 Elsevier Science B.
V. All rights reserved.