Final answer:
In the mid-1960s, scientists Arno Penzias and Robert Wilson pointed their large antenna in Holmdel, New Jersey to measure astronomical sources. They found unexpected background noise coming from all directions, which they determined was real and originating from space.
Step-by-step explanation:
In the mid-1960s, Arno Penzias and Robert Wilson of AT&T's Bell Laboratories pointed their large antenna in Holmdel, New Jersey to measure astronomical sources, including supernova remnants. However, they were surprised to find that the antenna was picking up unexpected background noise from all directions, similar to static on a radio. After investigating and ruling out various possibilities, they concluded that the background radiation was real and coming from space.