21 - Closed steady-state models

Summary

G.F.R. Ellis’s late 1970s exploratory model, the topic of the chapter, reverse-engineered the current state of the universe into an inhomogeneous static state with two centers located at the opposite sides and our galaxy very close to one of them. This relativistic framework attempted to bypass the cosmological principle as an unjustified assumption while agreeing with the observations, including the measurements of the CMB, and offering alternative explanations of the key parameters (e.g., the observed redshift of galaxies has a gravitational origin). In the model, the CMB photons are continuously produced at one center (singularity) and annihilated at the other. Variations of the model were worked out, and another model similar in spirit was devised by Phillips in the 1990s. It introduced two singularities (poles) and two kinds of matter that circulate across the universe from one center to another. The hot plasma near the singularity acted as a perfect black body radiating the redshifted CMB. The chapter discusses the epistemic virtues of these models (e.g., the “natural” origin of CMB photons as in the orthodox approach) and their observational refutation and mentions a related model by P.C.W. Davis.