Geometry & CMB Anisotropy (Lecture #27c of a course on Relativity & Cosmology)

Part 7 The Big Bang Cosmology (Book Ch 9, and video lectures #25 to #27)
Course textbook: A College Course on Relativity and Cosmology by Ta-Pei Cheng

Description: Extrapolating back in the time of an expanding universe suggests a big hot beginning. As the universe expands and cools, the system must pass through thermal equilibria with various constituent particles. This picture is strongly supported by the presence in the present era of these big bang thermal relics, for instance, the light nuclear elements of helium, deuterium, etc. with just the correct relative abundance. Most importantly, the decoupled photons became the cosmic microwave background (CMB) observed today; the statistical feature of its anisotropy contains much information about the geometry and energy contents of the universe.

Learning objective: Understanding how the big bang theory is supported by the observed thermal relics of the cosmic microwave radiation and the abundance of light nuclear elements, etc.