Geocentric theory

As an example of the insufficiency of present usefulness and self-consistency as grounds for belief in a scientific construct, it may be in order to recall some scientific history. In our own field we have the familiar example of phlogiston and in astronomy the example of epicycles. By the use of epicycle superimposed on epicycle, the geocentric theory was able to give a self-consistent, popular, and accurate description of apparent planetary motions. The epicycle treatment is analogous to a Fourier analysis of the motions and its accuracy did not guarantee the physical reality of epicycles. 

The primary objective of modern science is to construct theories that faithfully describe the reality. Theories are nothing but models that are subject to perpetual experimental scrutiny and checks of internal consistency. When a particular theory is abandoned, it is for one of several reasons. Some theories, such as those of flogiston and caloric, are simply proven wrong. Others, such as the geocentric theory of the universe, are superseded by simpler descriptions of reality. Finally, some formalisms (such as the Newtonian mechanics) are found to possess only a limited validity or to constitute special cases of more general (unified) theories. 

See also Celestial mechanics Geocentric theory Heliocentric theory Kepler s laws. 

The year 1543 also saw the appearance of another book that not only challenged the ancient authorities, but was also to have a profound impact on the way people perceived their place in the universe. The book was De revolutionibus orbium coelestium by Nicolaus Copernicus (1473-1543). On the basis that predictions of the future positions of the planets made using Ptolemy s geocentric theory were inaccurate, Copernicus proposed that the sun was at the centre of the universe, and the planets, including the earth, revolved around it. Copernicus still believed in the sphere of the stars, but man s unique position at the centre of all things was gone. 

One classic example of a scientific paradigm shift is the transition from a geocentric (Earth-centered) to heliocentric (Sun-centered) model of the universe. Invention and development of the telescope allowed for greater observation of the planets and the Sun. The theory that the Sun is the center of the universe around which the planets, including the Earth, rotate gained acceptance largely because of the advances in observational technology. 

Geocentric model based on religious beliefs, but explains observed phenomena. Careful observations (Brahe, 9 planets eventually Kepler) point to discovered. Discovery of Heliocentric Model first Neptune confirms Newton s suggested by Copernicus. theory of universal Telescope confirms model. gravitation. Anomaly in orbit of Mercury resists solution with Newton s laws. Precession of Mercury s orbit is solved by Einstein s Theory of General Relativity. Theory and observations agree. Pluto is demoted to non-planet status (4). 

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