On a bright spring morning 50 years ago, two young astronomers at Bell Laboratories
 were tuning a 20-foot, horn-shaped antenna pointed toward the sky over New Jersey.
Their goal was to measure the Milky Way galaxy, home to planet Earth.
To their puzzlement, Robert W. Wilson and Arno A. Penzias heard the insistent hiss of
radio signals coming from every direction—and from beyond the Milky Way. It took a
full year of testing, experimenting and calculating for them and another group of
researchers at Princeton to explain the phenomenon: It was cosmic microwave
background radiation, a residue of the primordial explosion of energy and matter that
suddenly gave rise to the universe some 13.8 billion years ago. The scientists had found
evidence that would confirm the Big Bang theory, first proposed by Georges Lemaître in 1931.