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Some FRW models with variable G and Λ. (English) Zbl 0870.53073
Summary: Einstein’s field equations with G and Λ both varying with time are considered in the context of general homogeneous, isotropic universes in a way which conserves the energy momentum tensor of the matter content. It is found that the solutions of the field equations, which are based on the variation of Λ as R -2 but with different constants of proportionality, describe significantly different cosmological scenarios. It is also found that the non-static models with constant density having a vacuum-like equation of state are endowed with inflation for a wide class of functions G(t) and Λ(t), and a static universe with constant density without the vacuum-like equation of state can exist only for k=1 with constant G and Λ.
53Z05Applications of differential geometry to physics
83F05Relativistic cosmology