**Introduction**

Against my better judgement, I agreed to post a summary of the arguments that demonstrate that geocentrism (the doctrine that the earth is the unmoving centre of the universe) is not a tenable hypothesis for a reasonable person with a moderate knowledge of modern physics. Please note that I am not seeking to show heliocentrism or any-other-centrism, merely that geocentrism is not a tenable hypothesis. Here we go.

The whole argument can be summarised in one sentence, so if you can’t be arsed to read the whole thing, just read the next sentence:

[list]

*]In Newtonian mechanics, geocentrism cannot be true for many physical reasons; in General Relativity the centre of the universe has no meaning, so to claim that the earth is the centre of the universe is meaningless; in neither system can the earth be said to be the unmoving centre of the universe

[/list]I’ll also argue that the promotion of geocentrism is unnecessary for salvation, is contrary to reason, and represents a major source of scandal, calling ridicule down on the Church and the Faithful

OK, let’s start. (I have posted some of this material before and some of it is new.)

**In Newtonian mechanics, geocentrism cannot be true for many physical reasons

**Newtonian mechanics works within Euclidean geometry, which, for our purposes, we can summarise as a two dimensional spatial geometry based on an absolute space. Euclidean space is absolute and independent of matter or energy, which exist within Euclidean space without, in any way, affecting it. In addition, Newtonian mechanics relies on an additional dimension of absolute time.

Note that the concept of the equivalence of reference frames exists in Newtonian mechanics. It is a mistake to think that the idea that reference frames are equivalent is a new finding of Special or General Relativity. Indeed, the concept of relativity and the equivalence of reference frames was first understood by the great scientist, Galileo, whose name is given to the mathematical expressions used to transform between reference frames in Euclidean geometry - these expressions are called Galilean transformations after him.

Galilean relativity states that relative motions of systems of bodies are the same no matter what inertial reference frame they are in, where an inertial reference frame is one in which the motion of a body not subject to forces is in a straight line and uniform and where the acceleration of bodies is proportional to applied forces. In Newtonian mechanics inertial reference frames move uniformly and rectilinearly with respect to one another.

Newton used this property of Galilean relativity in his calculations of planetary motion. It follows from the definitions of inertial frames and their equivalence that the centre of mass of an isolated system of bodies is at rest in an inertial frame. Newton reasonably approximated the solar system as an isolated system of bodies (this is not strictly true, but the forces and influence of the rest of the universe on relative motions within the solar system are vanishingly small on the scale of years). Within this reference frame, he then calculated the accelerations that would result from the gravitational forces between the bodies. Newton rejected the notion of geocentrism and heliocentrism (neither of which were ever to make an appearance in physics again); instead it is the centre of mass of the system of bodies (in this case the solar system), that is at rest with respect to the reference frame - all the other bodies (including the sun) experience accelerations and are not therefore at rest in the inertial frame. The sun, of course, is vastly more massive than every other body in the solar system, and so its centre is nearly at the centre of mass of the solar system and nearly stationary with respect to it, but not quite. So heliocentrism, within the solar system, can be seen as a close approximation to the Newtonian case. All of this is true whether we observe this from an inertial frame at rest with respect to the solar system or the fixed stars, as we can transform between them using the Galilean transformation.

`***To be continued***`