Isotropic Expansion of Inhomogeneous Universe

Understand

We propose a cosmological model that describes isotropic expansion of inhomogeneous universe.

• The energy-momentum tensor that creates the spatial inhomogeneity may not affect the uniform expansion scaling factor $a(t)$ in the FLRW-like metrics.
• Such energy-momentum tensor may not be exotic; in fact any linear or non-linear $\sigma$-model has this feature.
• We show that the classical spatial inhomogeneity can be embedded in both inflation models and the traditional cosmological expansion by perfect fluid.