The Cosmological Principle: Theoretical and Empirical Foundations

The idea of the (“perfect”) cosmological principle (CP), viz. that the Universe presents the same aspect from any place at any time, is traced to the ancient Greek philosophers, who also suggested how such a cosmic order might work. The antithesis of this view, i.e. the Aristotelian-Ptolemaic world-picture, was to become the hallmark of the Dark Ages. The Copernican revolution constitutes the first step by science in a modern direction, and the advance of science is thus seen as a succession of world pictures, all centred on local systems, in a hierarchical progression. We demonstrate that the prevailing picture of the Universe as an evolving system is still trapped in a local mode of thinking: the Copernican revolution is unfinished.