Pseudoscience/Heliocentricism: Difference between revisions
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====390 BC====
(Greek) The first non-geocentric model of the universe was '''proposed''' by the Pythagorean philosopher Philolaus, who '''taught''' that at the center of the universe was a "central fire", around which the Earth, Sun, Moon and planets revolved in uniform circular motion. This system '''postulated''' the existence of a counter-earth collinear with the Earth and central fire, with the same period of revolution around the central fire as the Earth. The Sun revolved around the central fire once a year, and the stars were stationary. The Earth maintained the same hidden face towards the central fire, rendering both it and the "counter-earth" invisible from Earth.
The Pythagorean concept of uniform circular motion remained unchallenged for approximately the next 2000 years, and it was to the Pythagoreans that Copernicus (a [[Agencies/Jesuits|'''Jesuit''']]) referred to show that the notion of a moving Earth was neither new nor revolutionary.
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Harlow Shapley's work on globular clusters and Edwin Hubble's '''assumptions''' in 1924 showed that the Sun is not the center of the universe, cosmology moved on from heliocentrism to galactocentrism, which states that the Milky Way is the center of the universe.
Hubble's observations of redshift in light from distant galaxies '''assumed''' that the universe was expanding and acentric. As a result, soon after galactocentrism was '''formulated''', it was abandoned in favor of the '''Big Bang model''' of the acentric expanding universe. Further '''assumptions''', such as the Copernican principle, the cosmological principle, dark energy, and dark matter, eventually '''lead to the current model of cosmology''', Lambda-CDM (Lambda-Cold Dark Matter, or ΛCDM model is a mathematical model of the Big Bang '''theory''' with three major components: 1. a cosmological constant denoted by lambda associated with dark energy 2. the '''postulated''' cold dark matter denoted by CDM 3. ordinary matter).
The '''concept''' of an absolute velocity, including being "at rest" as a particular case, is ruled out by the principle of relativity, also eliminating any obvious "center" of the universe as a natural origin of coordinates. Even if the discussion is limited to the Solar System, '''the Sun is not at the geometric center of any planet's orbit''', but rather approximately at one focus of the elliptical orbit. Furthermore, to the extent that a planet's mass cannot be neglected in comparison to the Sun's mass, '''the center of gravity of the Solar System is displaced slightly away from the center of the Sun.''' (The masses of the planets, mostly Jupiter, amount to 0.14% of that of the Sun.) Therefore, a '''hypothetical astronomer''' on an extrasolar planet would observe a small "wobble" in the Sun's motion.
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