Arno Penzias

Arno Allan Penzias was born in Munich in 1933 to a Jewish family. In 1939, at the age of six, he and his younger brother were sent to England on the Kindertransport; their parents escaped Nazi Germany soon after, and the family reunited and emigrated to the United States, settling in New York. Penzias studied physics at the City College of New York, served in the U.S. Army Signal Corps, and earned his doctorate at Columbia University under Charles Townes, the inventor of the maser, working on radio astronomy of interstellar gas.

In 1961 Penzias joined Bell Telephone Laboratories in Holmdel, New Jersey, where he was paired with Robert Wilson. The two acquired a 20-foot horn-reflector antenna originally built for the Echo satellite communication experiments and set about turning it into the most carefully calibrated radio telescope of its day. To use it for sensitive astronomy they had to account for every source of noise, and one source defeated them: a persistent, isotropic hiss corresponding to an antenna temperature of about 3.5 K that they could not eliminate by any means — including evicting nesting pigeons and cleaning their droppings from the horn.

Unaware that a Princeton group led by Robert Dicke was independently predicting and preparing to search for relic radiation from a hot early universe, Penzias and Wilson had in fact detected exactly that: the cosmic microwave background, the redshifted afterglow of the era of recombination. Their 1965 paper, a model of cautious understatement, announced the measurement; Dicke's companion paper supplied the cosmological interpretation. The detection settled the decades-long debate between the Big Bang and steady-state models decisively in favor of the Big Bang.

Penzias and Wilson shared the 1978 Nobel Prize in Physics for the discovery. Penzias went on to a distinguished career in research management at Bell Labs, eventually serving as its Vice President of Research, and later worked as a venture capitalist in Silicon Valley. He remained an influential voice on the role of basic research in industry until his death in 2024.