Cosmic Microwave Background
First published: 2017
Brief summary
NASA overview of CMB radiation and early-universe fluctuations.
Article
The linked NASA page presents the Big Bang framework for the origin and evolution of the universe. It describes cosmology as the study of how the universe began, developed and acquired its present large-scale structure, while noting that important questions remain unresolved.
The cosmic microwave background is identified as the oldest light that can be observed. It was released when the expanding universe had cooled enough for light to travel freely, and it now appears as faint microwave radiation arriving from every direction.
Small variations in this background record differences in the density of the early universe. Those differences provided the initial conditions from which matter later accumulated into stars, galaxies and larger cosmic structures under gravity.
Observations of the cosmic microwave background are used with measurements of cosmic expansion and large-scale structure to test models of the universe. The currently linked page is a broad overview and does not itself provide a detailed discussion of the CMB acoustic-peak spectrum.
Source details and credits
- Source / publisher: NASA Science
- Source type: Educational article
- URL type: WWW
- Credits: NASA Science
- URL: https://science.nasa.gov/astrophysics/focus-areas/what-powered-the-big-bang/