Cosmic background radiation

Cosmic Background Radiation is the residual radiation that fills the observable universe and is a remnant from an early stage of the universe, also known as the Big Bang. It is isotropic to roughly one part in 100,000 and has a nearly perfect black-body spectrum. It has a temperature of 2.72548±0.00057 K. The Cosmic Background Radiation is an important source of data on the early universe because it is the oldest electromagnetic radiation in the universe, dating to the epoch of recombination.

Discovery

The Cosmic Background Radiation was first predicted in 1948 by Ralph Alpher and Robert Herman. It was first observed inadvertently in 1965 by Arno Penzias and Robert Wilson at the Bell Telephone Laboratories in Murray Hill, New Jersey. The discovery earned them the 1978 Nobel Prize in Physics.

Characteristics

The Cosmic Background Radiation is almost perfectly uniform and isotropic. It varies by less than 0.003% in all directions. This uniformity is one strong argument for the Big Bang theory, as it is exactly what the theory predicted.

Significance

The Cosmic Background Radiation is a snapshot of the universe when it was just 380,000 years old. It provides a unique probe of the conditions of the early universe and the physics that governed its evolution.

See also

• Big Bang
• Cosmic microwave background polarization
• Cosmic neutrino background
• Cosmic infrared background
• Cosmic X-ray background