Olbers’ paradox

In an infinitely extended universe that does not change over time and is evenly filled with stars, the “night sky” would look as bright as the surface of the sun. The reason: The farther away a star, the weaker the light we receive from it. But: The greater the distance, the greater the number of stars that have exactly that distance from us. In an eternal and infinite universe, the two effects cancel exactly.

The big bang models based on Einstein’s general theory of relativity, with a changing universe evolving out of a hot initial state, make no such counter-factual prediction.