It is shown that the infinite energy density of zero-point radiation can be renormalized to a finite value, Kroc2 , where Kro is the inertial mass density corresponding to gravitational mass density ro , by inclusion of gravitational self-potential energy, provided that 4pGroR2 = 3Kc2, which is the condition that Kroc2 closes the universe at radius R. When material mass m* is renormalized in the same way the result is mbrg = -cm* 2hc1- r 2 R2 h. Negative mass m(r) interacting gravitationally with positive ro is accelerated outwards subject to Kg 2mbrg = constant, where g = - b - 1 2 1 c h 2 , so that matter of the universe expands with velocity field b = r R. The Hubble redshift can therefore be given a Doppler interpretation. A velocity field b = r R and a Doppler interpretation of Hubble's effect are obtained in de Sitter cosmology, but only as one of several equally valid interpretations depending on reference system. For Robertson coordinates the Hubble redshift emerges in exponential form and receives a "tired light" interpretation in a stationary universe. The same must be expected for extended Newtonian cosmology.
Following previous work, Planck radiation oscillators are quantized gravitationally as eigenstates of a fundamental oscillator of minute constant energy wo , where wo = c R. Quanta wo (gravitons) can be scattered from the w-radiation field to the w? -radiation field, redshifting one and blueshifting the other so that it is possible for an arbitrary radiation spectrum to attain the equilibrium blackbody spectrum without interacting with matter. The redshift dw over the path d in a medium with radiant energy density is dw w = -AUd , where A is a constant with theoretical value A = 6.4 ?10-21 erg-1 cm2. When U = Kroc2 the redshift law reduces to Hubble's law dw w = -d R, which integrates to the exponential form obtained in de Sitter cosmology with Robertson coordinates.
When U is the radiant energy density in a quasar there arise local (anomalous) redshifts exceeding the Hubble redshift. For a quasar at distance r the Hubble redshift varies as r, but the value of U varies as r2 . It is found that the local redshift dominates the Hubble redshift for r > r *, where r * = 0.014R is estimated from observed quasar fluxes and dimensions. The anomalous distribution of high-redshift quasars is explained. A possibility for testing the redshift law in the laboratory is explored briefly.
