Cosmic microwave background discovery (1965)
May 1965What Happened
Arno Penzias and Robert Wilson, working at Bell Labs in Holmdel, New Jersey, found a persistent microwave hiss they could not eliminate from their horn antenna. Princeton physicists Robert Dicke and Jim Peebles identified the signal as leftover radiation from the Big Bang, cooled to about 3 Kelvin. The two groups published back-to-back papers in Astrophysical Journal Letters.
Outcome
The detection became the strongest evidence for the Big Bang model and ended a long debate with steady-state cosmology.
Penzias and Wilson shared the 1978 Nobel Prize in Physics. Later satellites (COBE, WMAP, Planck) mapped the CMB in detail and fixed the universe's age, geometry, and composition.
Why It's Relevant Today
Like the cosmic microwave background, the cosmic web was predicted decades before anyone could see it directly. Direct observation moves cosmology from inference to measurement.
