On the Newtonian Cosmology Equations with Pressure
  The basic equations describing a Newtonian universe with uniform pressure are reexamined. We argue that in the semi-classical formulation adopted in the literature the continuity equation has a misleading pressure gradient term. When this term is removed, the resulting equations give the same homogeneous background solutions with pressure and the same evolution equation for the density contrast as are obtained using the full relativistic approach. 
J.A.S. Lima (UF Rio Grande do Norte and Brown Univ.), V. Zanchin (UF   Santa Maria and Brown Univ.) and R. Brandenberger (Br...