Spherical light waves independent of the motion of the frame of reference of the observer are obtained by assigning to the Aether fluid three effects: (I) dilation of times, (ii) contraction of lengths in the direction of Aether motion, and (iii) a velocity-dependent refractive index. Applying to constant units time dilation and length contraction appropriate for the free-fall velocity field of a Newtonian potential field, one obtains coordinate-dependent units (unit fields) in terms of which measurements obey the laws of geometry for flat Minkowski space-time. The Newtonian model of a universe, namely a uniformly dense sphere with finite radius, provides unit fields (derived from free-fall velocity) whose transformation to constant units changes Minkowski geometry to de Sitter geometry.
In order to derive de Sitter space-time with uniform mass density from the Einstein field equations it is necessary to replace matter source term kTab by the cosmological term Lgab . Then a single physical constant L specifies a Universe, which is reasonable if a Universe is defined with respect to mass M as absorber ?bMg of Aether disturbances from M when M is accelerated. The exact distribution of matter surrounding M does not affect the gravitational potential Fo at M in the rest frame of M because the boundary surface of the Universe (a horizon) adjusts so as to maintain constant Fo. The same is true for another mass M? . A universe, so defined, is one of an infinity of Universes, each of which is an inertially isolated system in an infinite Cosmos. The redshift is shown to be capable of different interpretations, including Dopplergravitational and "tired light." Mass density of the Universe is that of vacuum fluctuations whose positive divergent electromagnetic energy density is renormalized by divergent negative gravitational self potential energy to a finite negative value. Thus a mass falls outwards in the Newtonian Universe with negative mass density. Energy conservation demands that matter be created when mass in highly degenerate stars attains the negative energy vacuum state. It is shown how entropy decreases with the onset of degeneracy in stars.
