The Big Bang theory was first developed in the 1940s and even then predicted the existence of the microwave background. But only in the 1960s did a group of physicists at Princeton begin to search for it.

At about the same time, Arno Penzias and Robert Wilson, two radio astronomers at Bell Labs, began a study of the radio emissions from our galaxy. Their antenna is shown behind them in the photograph. At first, they were surprised to find persistent, unexplained noise in their antenna. The noise was independent of time of day, the season of the year, and the direction their antenna pointed. Without knowing it, Penzias and Wilson had discovered the microwave background! To help understand their observations, they called the leader of the Princeton group, Robert Dicke, who explained the source of the noise and then announced to his group, “We've been scooped.”

Penzias and Wilson received the Nobel Prize in 1978 for their discovery.

Arno Penzias and Robert Wilson, in front of their microwave antenna (photo courtesy of Lucent Technologies, Inc.)