About 400 photons in every cubic centimeter of space are 13.8 billion years old. They are the ancient light left over from when matter and antimatter annihilated each other at the beginning of time. That primordial flash never truly faded, it simply stretched with the expanding cosmos, cooling from a blinding glare into faint microwave static that still quietly falls on your roof tonight. In 1964, two radio astronomers accidentally captured this echo of creation while trying to scrub pigeon droppings off their giant antenna. That accidental hiss was the cosmic microwave background, and it earned them a Nobel Prize.