Astrophysics & Particle Physics-APPC 2026

The Cosmic Microwave Background (CMB) is the leftover radiation from the Big Bang, which is a snapshot of the universe around 380,000 years after it came into existence. It is the oldest observable record of the universe, providing vital insight into cosmology, cosmic inflation, and the development of large-scale structures.CMB radiation is seen as a slightly varied microwave signal throughout the sky, with small anisotropies—extremely small temperature and polarization variations—mapping out the distribution of matter and energy in the early universe. These oscillations sowed the seeds of galaxy, cluster, and cosmic structure formation.Observations of CMB have been conducted by space missions like COBE, WMAP, and Planck, giving extremely accurate observations of the makeup, geometry, rate of expansion, and curvature of the universe.

The CMB can be analyzed by scientists to find out the relative amounts of dark energy, dark matter, and normal matter, and to check predictions of Big Bang theory as well as cosmic inflation.The recombination period, when electrons and protons came together to create neutral hydrogen, enabled the free propagation of photons, resulting in the CMB radiation detected today. Polarization patterns in the CMB also carry information about primordial gravitational waves, offering a window into high-energy physics and the early moments of the universe.By studying the CMB, cosmologists can trace the history of the universe, the formation of large-scale structures, and the fundamental physical processes that shaped cosmic evolution.

The CMB continues to be a foundation of contemporary cosmology, linking theoretical frameworks with observational information and allowing scientists to know about the birth, structure, and destiny of the universe.The Cosmic Microwave Background is not only a remnant of the early universe but also an extremely sensitive probe of fundamental physics, a test of cosmological models, and a chart of the universe's development, thereby being an essential topic in astrophysics and cosmology.