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Olber's paradox

The puzzle of why the night sky is not as uniformly bright as the surface of the Sun if, as used to be assumed, the universe is infinitely large and filled uniformly with stars. It can be traced as far back as Johannes Kepler in 1610, was discussed by Edmond Halley and Philippe Loys de Chéseaux in the 18th century, but wasn't popularized as a paradox until Heinrich Olbers took up the issue in the 19th century. It is completely resolved in the standard Big Bang cosmology, according to which the universe has a finite age (providing a horizon beyond which we can't see) and contains a finite number of stars.

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