Cosmic Microwave Background
The faint thermal radiation filling all of space, the afterglow of the early universe.
Also: CMB · relic radiation
Definition
The Cosmic Microwave Background (CMB) is the thermal radiation that fills all of space, representing the afterglow of the hot, dense early universe approximately 380,000 years after the Big Bang, when the universe had cooled enough for atoms to form and became transparent to radiation. The CMB has a near-perfect blackbody spectrum at a temperature of 2.725 K. Tiny temperature fluctuations in the CMB encode the seeds of the large-scale structure of the universe.
Example
“The Planck space mission mapped the CMB temperature fluctuations across the entire sky at unprecedented resolution, revealing subtle patterns that match the predictions of cosmic inflation and providing the most precise measurements of the universe's age, composition, and geometry.”
Synonyms
- CMB
- relic radiation
- Big Bang afterglow
Images
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Related Terms
- Big Bang Theory
- Redshift
- Inflation
- Dark Matter