Vector field theories in cosmology

Recently proposed theories based on the cosmic presence of a vectorial field are compared and contrasted. In particular the so-called Einstein æther theory is discussed in parallel with a recent proposal of a strained space-time theory (cosmic defect theory). We show that the latter fits reasonably well the cosmic observed data with only one, or at most two, adjustable parameters, while other vector theories use much more. The Newtonian limits are also compared. Finally we show that the cosmic defect theory may be considered as a special case of the æther theories, corresponding to a more compact and consistent paradigm.

Figure 1

Expansion rate of the universe versus the scale factor $a$ according to the CD theory. The graph is valid both for empty spacetime and for a universe filled with an incoherent dust.