Answer :
Final answer:
Penzias and Wilson discovered the Cosmic Microwave Background while looking for astronomical sources using a microwave antenna.
Explanation:
Penzias and Wilson were looking to measure astronomical sources with a delicate microwave antenna they built at AT&T's Bell Laboratories. They discovered the Cosmic Microwave Background (CMB), a faint afterglow of radio waves that permeates the universe, coming from all directions at once.
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