Cosmological models with dynamic equations of state

Abstract EN

Assuming a locally rotationally symmetric Bianchi type I metric, two cosmological models are constructed for a perfect fluid with a dynamic equation of state p = (γ-1)μ, y = γ (t).

Both models are shown to have an initial radiative big bang ”pancake“ singularity.

However, one model approaches the Friedman-Robertson-Walker spacetime as t→∝ , while the other becomes isotropic at a finite time and goes on evolving to an anisotropic spacetime thereafter.