Bound for entropy and viscosity ratio of strange quark matter

High energy density (ϵ) and temperature (T) links general relativity and hydrodynamics leading to a lower bound for the ratio of shear viscosity (η) and entropy density (s). We get the interesting result that the bound is saturated in the simple model for quark matter that we use for strange stars at the surface for T∼80 MeV. At this T we have the possibility of cosmic separation of phases. At the surface of the star where the pressure is zero-the density ϵ has a fixed value for all stars of various masses with correspondingly varying central energy density ϵc. Inside the star where this density is higher, the ratio of η/s is larger and are like the known results found for perturbative QCD. This serves as a check of our calculation. The deconfined quarks at the surface of the strange star at T=80 MeV seem to constitute the most perfect interacting fluid permitted by nature.