The cosmic microwave background

Lore & Background

The first published recognition of the CMB as a detectable phenomenon appeared in a brief paper by Soviet astrophysicists A. G. Dicke at Princeton University, began constructing a Dicke radiometer to measure the CMB. That same year, Penzias and Wilson at Bell Telephone Laboratories in Holmdel Township, New Jersey, built a Dicke radiometer intended for radio astronomy and satellite communication experiments. After a telephone call from Crawford Hill, Dicke said 'Boys, we've been scooped.' A meeting between the Princeton and Crawford Hill groups determined the antenna temperature was due to the microwave background.

Reader's Guide

The cosmic microwave background is the most important observational evidence for the Big Bang theory. Ground and space-based experiments such as COBE, WMAP, and Planck have measured temperature inhomogeneities, revealing a power spectrum with peaks that hold information about the early universe: the first peak determines overall curvature, the second and third detail densities of normal matter and dark matter. The CMB also has angular variation in polarization, with E-mode and B-mode signals.

Did You Know?

• The first peak of the CMB power spectrum determines the overall curvature of the universe.