A Book Cosmological Models

A solution of the Einstein equations is by definition cosmological if it can reproduce the Friedmann (1922, 1924), Lemaitre (1927, 1931), Robertson (1929, 1933), and Walker (1935) (FLRW) metric by taking limiting values of arbitrary constants or functions. It has been a conventional wisdom in cosmology that the FLRW models successfully describe the large scale properties of our observed Universe, even since the 1930ies.