Background microwave radiation

Using a big horn-shaped antenna built to detect radio reflections, Penzias and Wilson found an unexplainable excess of radio emissions coming from all directions with equal intensity. This was the predicted background radiation that would be a consequence of the big bang.
 Arno Allan Penzias and Robert Woodrow Wilson United States 1964 Background microwave radiation

Using a big horn-shaped antenna built to detect radio reflections, Penzias and Wilson found an unexplainable excess of radio emissions coming from all directions with equal intensity. This was the predicted background radiation that would be a consequence of the big bang.