The expanding universe and thermal relics

Ta-Pei Cheng

in Relativity, Gravitation and Cosmology

Second edition

Published in print November 2009 | ISBN: 9780199573639
Published online February 2010 | e-ISBN: 9780191722448 | DOI:

Series: Oxford Master Series in Physics

                      The expanding universe and thermal relics

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The dynamics of a changing universe are determined by Friedmann equations, which have simple quasi-Newtonian interpretations. The universe began hot and dense (the big bang), and thereafter expanded and cooled. The early universe had undergone a series of thermal equilibriums (e.g., neutrino decoupling). The observed abundance of the light nuclear elements (helium, deuterium, etc.) match well with their being the product of the big bang nucleosynthesis. When the universe was 360,000 years old, photons decoupled, and they remain today as the primordial light having a blackbody spectrum with temperature T=2.725K. The cosmic microwave background (CMB) is not perfectly uniform. The higher multipoles contain much information about the geometry, matter/energy content of the universe, as well as the initial density perturbation out of which grew the cosmic structure we see today.

Keywords: Friedmann equations; quasi-Newtonian interpretation; critical density; big bang cosmology; nucleosynthesis; helium; deuterium; cosmic microwave background; CMB anisotropy; neutrinos

Chapter.  16136 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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