Which evidence supports the idea that cosmic microwave background radiation is a remnant of the big bang
There are several pieces of evidence that support the idea that cosmic microwave background (CMB) radiation is a remnant of the Big Bang:
1. Uniformity and isotropy: The CMB radiation is nearly isotropic and uniform, meaning it has the same temperature in all directions of the sky. This indicates that it originated from a highly uniform and balanced event, such as the Big Bang explosion, which would have spread radiation evenly throughout the universe.
2. Redshift: The CMB radiation has a redshift, meaning its wavelengths have been stretched due to the expansion of the universe. This supports the idea that the radiation originated from an intense, compact source billions of years ago, which has since expanded and cooled.
3. Predicted existence: The existence of CMB radiation was predicted by the Big Bang theory itself. In the 1940s, physicists George Gamow, Ralph Alpher, and Robert Herman theorized that if the universe started with a hot, dense phase (the Big Bang), it would have left behind a faint radiation after it expanded and cooled. This prediction was confirmed in 1965 by the discovery of the CMB radiation by Arno Penzias and Robert Wilson.
4. Anisotropies: While the CMB radiation is mostly uniform, it also exhibits small fluctuations in temperature. These anisotropies provide valuable information about the early universe, as they are thought to arise from density fluctuations that eventually grew into galaxies and other cosmic structures. The precise measurements of these anisotropies from various satellite missions, such as the Cosmic Background Explorer (COBE), the Wilkinson Microwave Anisotropy Probe (WMAP), and the Planck spacecraft, have further supported the Big Bang theory.
Overall, the uniformity, redshift, predicted existence, and anisotropies observed in the CMB radiation all strongly support the idea that it is a remnant of the Big Bang.