Cosmic Background Radiation
Cosmic Background Radiation refers to the electromagnetic radiation filling the universe, primarily observed as the Cosmic Microwave Background (CMB). It serves as the thermal afterglow of the Big Bang, providing critical evidence for the universe’s hot, dense origin and subsequent expansion.
Key Concepts
- Thermal Remnant: The CMB is a nearly uniform blackbody radiation at ~2.7 K, representing the cooled remnant of the early universe’s recombination epoch.
- Isotropy and Anisotropy: While largely isotropic, tiny temperature fluctuations in the CMB map the seeds of large-scale structure formation.
- Olbers’ Paradox Resolution: The darkness of the night sky is explained by the finite age of the universe and the expansion of space, which redshifts light and limits the observable horizon. This connects directly to the discussion on why the sky is not infinitely bright: Olbers’ Paradox: Why the Night Sky is Dark.
- Cosmological Principle: The uniformity of background radiation supports the assumption that the universe is homogeneous and isotropic on large scales.
Related Concepts
- Big Bang Theory
- Redshift
- Observable Universe
- Dark Energy
- Structure Formation