The following is part of a lecture series on cosmology. In this lecture, we first provided a mathematical description of homogeneity and isotropy. Then, we derived the Friedmann–Lemaître–Robertson–Walker metric. And Finally, we used this metric to describe the possible spatial geometries of a homogeneous and isotropic universe.

Chapters:
00:00 - Introduction
00:11 - Outline of lecture
00:32 - Units and conventions
01:14 - Homogeneity and isotropy
04:04 - Homogeneous and isotropic metric
06:25 - FLRW metric
08:26 - Possible spacetime geometries