In a geocentric universe...

[drelda]

OK - but if we allow an external frame of reference then there is a real distinction? eg for the solar system we could use the positions of nearby stars as the frame of reference.

From that perspective its clear that the solar system doesn't revolve around a static earth isnt it?

For the universe as a whole we can't have such an external frame of reference - so the laws of physics say nothing about which reference we choose to use?

However - I'd argue there is still a reason not to choose the geocentric model. In the case of the solar system the motions of the planets are simple and elegant with the sun at the center - in the geocentric model they are really complicated and messy. Therefore the sun centered model of the solar system is 'better' - even without an external frame of reference.

I guess the same goes for the universe as a whole. Because the earth spins it makes the geocentric model a nightmare compared to the alternative - regardless of the physics refusing to rule it out.

Therefore all we need to do is stop the earth spinning... then it would be much easier to assume the earth was the center of the universe .

- Drelda

 

[BowlOfRed]

However - I'd argue there is still a reason not to choose the geocentric model. In the case of the solar system the motions of the planets are simple and elegant with the sun at the center - in the geocentric model they are really complicated and messy. Therefore the sun centered model of the solar system is 'better' - even without an external frame of reference.

Of course. That was already mentioned.

Some coordinate systems are much more convenient than others. Geocentric coordinates where the earth isn't rotating are great for doing calculations related to navigation on the earth's surface, but terrible for astronomy.

Just don't think that because it's better choice for some purpose that it is "more correct" or "what is really happening" compared to an alternative system.

 

[sol invictus]

OK - but if we allow an external frame of reference then there is a real distinction? eg for the solar system we could use the positions of nearby stars as the frame of reference.

From that perspective its clear that the solar system doesn't revolve around a static earth isnt it?

Well, if you were sufficiently masochistic you could choose coordinates where the nearby stars are fixed but the sun is revolving around the earth. There'd be some kind of horrible swirly thing (to use a technical term ) happening to the space in the middle. It would be a terrible mess, but it would be mathematically (and physically) consistent.

For the universe as a whole we can't have such an external frame of reference - so the laws of physics say nothing about which reference we choose to use?

They say we can use any one we like, and tell us how to formulate the laws in whichever one we choose.