In ancient times, the Ptolemaic system, in which the planets circle the Earth resting at the center, displaces the mythical models of the Egyptians and Babylonians. At the beginning of the modern era, the Copernican system, with the Sun resting at the center, becomes generally accepted. Constructions of a self-contained world, like Descartes’, expand Copernicanism with assumptions about the entire universe and the relativity of motions. With Newton’s Theory of Gravity and his idea of absolute space, the assumption of absolute movements becomes generally accepted. Einstein’s General Theory of Relativity, however, makes relativistic spacetime the foundation of all modern cosmologies.