Cosmic Microwave Background Radiation

  • Cosmic Microwave Background Radiation (CMBR) is the thermal radiation left over from the “Big Bang”. This term often comes up in discussions about the origins and overall structure of the universe.
  • CMBR was first discovered in 1965 by Arno Penzias and Robert Wilson. Their landmark detection provided substantial evidence to support the Big Bang Theory.
  • CMBR fills all observable space and its presence is a crucial piece of evidence for the Big Bang Theory. Its consistency and uniformity in all directions suggests that the early universe was homogeneous and isotropic.
  • The radiation is isotropic to roughly one part in 100,000: the root mean square variations are only 18 µK, after subtracting out a dipole anisotropy from the Doppler shift of the background radiation.
  • The properties of CMBR, including its uniform temperature of about 2.7 Kelvin (approximately -270.45 degrees Celsius), tell us that the universe began as a hot, dense state and has been expanding and cooling since then.
  • Differences in the brightness (or temperature) of CMBR in different directions corresponds to minute density fluctuations in the early universe. These perturbations (tiny temperature differences) jumped-started the formation of stars and galaxies after the Big Bang.
  • CMBR doesn’t interact strongly with matter, which means it carries pristine information about the early universe across billions of years of cosmic time.
  • Detailed analyses of the tiny temperature variations in the CMBR across the sky provide a map of the early universe. This mapping has allowed scientists to determine the age of the universe, the total energy content of the universe, and the speed of its expansion or ‘inflation’.
  • The study of the CMBR continues to offer insights into fundamental physics and cosmology, serving as a crucial tool in our deeper understanding of the universe and its origins. Understanding and revising this concept can help decode higher-level constructs of the universe.