Glossary term: Cosmological Principle

Description: The cosmological principle is the basis for modern cosmology and is built on observations and a fundamental assumption. It states that spatially the Universe is isotropic and homogeneous on large scales (clusters of galaxies). Observations on sufficiently large scales, show that the Universe appears to "look" the same in any direction; there is no preferred direction (isotropic). The fundamental assumption, based on the Copernican Principle (humans do not occupy a special location in the Universe), is that the Universe is the same everywhere (homogeneous); there appears to be no preferred location. The cosmological principle is accompanied by universality, where the laws of physics and the fundamental constants are the same everywhere in the Universe, here on Earth or a distant galaxy.

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