Explore the cosmic microwave background radiation spectrum—the oldest light in the universe, dating back to 380,000 years after the Big Bang.
The Cosmic Microwave Background (CMB) is the remnant radiation from the Big Bang, dating back to approximately 380,000 years after the universe's birth. At this time, the universe had cooled enough for electrons and protons to combine into neutral hydrogen atoms, making the universe transparent to light for the first time.
The CMB fills the entire sky uniformly, with a temperature of approximately 2.725 Kelvin (-270.4°C). This radiation has been redshifted by the expansion of the universe from its original visible and ultraviolet wavelengths to the microwave range we observe today.
The spectrum shown in this visualization represents a perfect blackbody curve, matching theoretical predictions with extraordinary precision. This agreement provides strong evidence for the Big Bang theory and our understanding of the early universe.
The CMB spectrum is one of the most important observations in cosmology. Its perfect blackbody shape confirms that the early universe was in thermal equilibrium, while tiny temperature fluctuations (anisotropies) reveal the seeds of cosmic structure formation.
Measurements of the CMB by missions like COBE, WMAP, and Planck have provided precise values for fundamental cosmological parameters, including the age of the universe (13.8 billion years), the composition of matter and energy, and the geometry of space.
The CMB continues to be a rich source of cosmological information. Future observations will probe even smaller scales, potentially revealing evidence for cosmic inflation, gravitational waves from the Big Bang, and other fundamental physics phenomena.