I misunderstood the Physics? Fair enough - so help me out... What is the correct reference frame?
There is no such thing as a 'correct' reference frame. There are just simplier reference frames than others.
I know why geocentrism is a dumb area - it does not match observation (and therefore reality).
Okay, perhaps I should distinguish here. The older ideas of geocentrism certainly did have different predictions - but these ideas were based on the idea that all
the planets orbited the Earth. This is clearly not the case, without making extremely convoluted laws of physics up. It's simply far less laden with convoluted 'fixes' to the theory if you have Newton's laws (or Einstein's theory) as valid, and the planets orbiting about a common centre of mass which is within the Sun.
Now, these days we also have an understanding that motion is
relative, that it's daft to say that such and such is moving (or even rotating) without specifying with
respect to what. (If you're interested in why rotations are also included in this, and what RichardT's rather confused posts are about, read about Mach's insights and Newton's Bucket. Or go
here for a pretty good summary. But the synopsis is that the old notion of absolute motion is simply wrong. RichardT is taking this to mean that geocentrism and heliocentrism are identical - by which he is meaning that the viewpoint of the Sun being the centre of your coordinte system is physically identical the Earth being the centre of your coordinate system.
In this case, he is correct but he has just made geoecentrism
redundant. The whole point of geocentrism was that the Earth is somehow
special, but by taking this view he has reduced geocentrism to just a complicated picture of heliocentrism. And that makes it pointless to consider.