  The viscosity of hadronic matter is studied using a classical evaluation of
the scattering angle and a quantum mechanical discussion based on phase shifts
from a potential. Semi classical limits of the quantum theory are presented. A
hard sphere and an attractive square well potential step are each considered as
well as the combined effects of both. The lowest classical value of the
viscosity for an attractive potential is shown to be a hard sphere limit. The
high wave number-short wavelength limits of the quantum result have scaling
laws associated with it for both the viscosity and entropy. These scaling laws
are similar to the Fraunhoher diffraction increase for the hard sphere
geometric cross section. Specific examples for nuclear collisions are given.
The importance of the nuclear tensor force and hard core is mentioned. The
viscosity (eta), entropy density (s) and eta/s ratio are calculated for a gas
of dilute neutrons in the unitary limit of large scattering length. Away from
the unitary limit, the ratio of the interaction radius or the scattering length
to the interparticle spacing introduces a variable y besides the fugacity z.
The isothermal compressibility is shown to impose important constraints. The
results for eta/s are compared to the AdS/CFT string theory minimum of
(1/4Pi)hbar/kb to see how close a nucleonic gas is to being a perfect fluid.
The eta/s ~1hbar/kb for a neutron gas in its unitary limit. The eta/s 3hbar/kb
treating the nuclear scattering as billiard ball collisions. The minimum eta/s
for a neutron gas occurs in regions of negative isothermal compressibility and
high fugacity where higher virial terms are important. In a neutron-proton
system higher virial terms are associated with a liquid-gas phase transition
and critical opalescent phenomena.The type of flow-laminar,vortex, turbulent-
is investigated.

Nuclear Theory