Concept

Cosmic Microwave Background

Also Known As CMB

Cosmology and the Early Universe

The faint glow of microwave radiation filling the whole sky, released about 380,000 years after the Big Bang when the young universe first became transparent to light. Its accidental detection by Arno Penzias and Robert Wilson in 1965 provided decisive evidence for the Big Bang model.

Facts

Concept Domain

Cosmology 1

Formulated Year

1965 2

Year of its detection by Penzias and Wilson; the radiation had been predicted theoretically in the late 1940s.

Proposed By

Ralph Alpher and Robert Herman 1

FAQs

Was the cosmic microwave background discovered on purpose?

No. Arno Penzias and Robert Wilson found it by accident in 1965 while testing a radio antenna, not while looking for it.

No. The cosmic microwave background was found accidentally in 1965 by Arno Penzias and Robert Wilson, who were testing a sensitive radio antenna at Bell Labs and could not get rid of a faint, uniform background noise no matter which direction they pointed it. The noise turned out to be the leftover glow released about 380,000 years after the Big Bang, when the young universe first cooled enough to become transparent to light. Because the signal matched a prediction cosmologists had already made for exactly this kind of relic radiation, its accidental discovery became decisive evidence for the Big Bang model rather than a puzzle that stayed unsolved.

Connections