The afterglow radiation from the Big Bang, now cooled to microwave frequencies and detectable as a faint radiation field filling all of space. It provides a snapshot of the universe when it first became transparent to light, about 380,000 years after the Big Bang.
First predicted in 1948 by Ralph Alpher and Robert Herman, then accidentally discovered in 1965 by Arno Penzias and Robert Wilson. The name describes its cosmic origin, microwave frequency range, and its role as a background radiation permeating space.
The CMB is baby pictures of the universe - tiny temperature fluctuations in this ancient light show the seeds that grew into all the galaxies and stars we see today! Every TV static contains about 1% signal from this primordial radiation.
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