The apparent contradiction between the simple observation that the night sky is dark and the theoretical expectation that an infinite, static Universe, filled more or less uniformly with stars and galaxies, should be as bright as the surface of a star. The first correct discussion of this paradox was published in 1744 by the Swiss astronomer (Jean) Philippe Loys de Chéseaux (1718–51); H. W. M. Olbers published his discussion of it in 1826. The paradox can be resolved by identifying its incorrect assumptions. Most important of these is that, as shown by the Big Bang theory, the Universe is not infinite, having come into being around 15 billion years ago. An additional, less important, effect is that the expansion of the Universe weakens the light from distant galaxies, but this on its own cannot fully explain the paradox.
Subjects: Astronomy and Astrophysics — Physics.