Copernican principle

Named for Copernican heliocentrism, it is a working assumption that arises from a modified cosmological extension of Copernicus' argument of a moving Earth.

Copernicus proposed that the motion of the planets could be explained by reference to an assumption that the Sun is centrally located and stationary in contrast to the geocentrism.

He argued that the apparent retrograde motion of the planets is an illusion caused by Earth's movement around the Sun, which the Copernican model placed at the centre of the universe.

Michael Rowan-Robinson emphasizes the Copernican principle as the threshold test for modern thought, asserting that: "It is evident that in the post-Copernican era of human history, no well-informed and rational person can imagine that the Earth occupies a unique position in the universe.

[7] In practice, astronomers observe that the universe has heterogeneous or non-uniform structures up to the scale of galactic superclusters, filaments and great voids.

[8] However, recent evidence from galaxy clusters,[9][10] quasars,[11] and type Ia supernovae[12] suggests that isotropy is violated on large scales.

Since the 1990s the term has been used (interchangeably with "the Copernicus method") for J. Richard Gott's Bayesian-inference-based prediction of duration of ongoing events, a generalized version of the Doomsday argument.

[17] Before the term Copernican principle was even coined, past assumptions, such as geocentrism, heliocentrism, and galactocentrism, which state that Earth, the Solar System, or the Milky Way respectively were located at the center of the universe, were shown to be false.