[Petrochemicals]

But space is curved and that is why the path is the shortest distance, that being the curved motion from the point of view of the observer. Due to the acceleration of gravity being greater one side as compared to the other. They are under there own relative motion. Only question is  which body is going under acceleration ?

[geordief]

But space is curved and that is why the path is the shortest distance, that being the curved motion from the point of view of the observer. Due to the acceleration of gravity being greater one side as compared to the other. They are under there own relative motion. Only question is  which body is going under acceleration ?

I think neither are  since an accelerometer on either body will read zero.

I also think it is spacetime (rather than space) which is curved

[Petrochemicals]

But space is curved and that is why the path is the shortest distance, that being the curved motion from the point of view of the observer. Due to the acceleration of gravity being greater one side as compared to the other. They are under there own relative motion. Only question is  which body is going under acceleration ?

I think neither are  since an accelerometer on either body will read zero.

I also think it is spacetime (rather than space) which is curved

But if relativity is to be believed, how could space be curved and relative from the point of the observer simultaniously ? Surely the observer should see a straight line space due to acceleration being relative ? I think pedant is the word.

[geordief]

But if relativity is to be believed, how could space be curved and relative from the point of the observer simultaniously ? Surely the observer should see a straight line space due to acceleration being relative ? I think pedant is the word.

Pedant? Do you mean "dependent"?

Do you disagree that we should be discussing "spacetime" rather than "space"?

It is not my understanding that motion caused by gravity can be called "relative acceleration" but I am not really qualified to give an opinion and will defer to others  better able to do so.

Actually it is my understanding that acceleration is not relative but absolute -but again  I could be wrong.

[Petrochemicals]

I do not see how space and "space time" are different.

Free fall acceleration of earth is dependant upon distance, is in no way constant


Thus will give a linear view to the observer, unless it is NOT relative ?

From https://en.m.wikipedia.org/wiki/Structure_of_the_Earth

Pedant https://www.thefreedictionary.com/pedant

[yor_on]

Ok Geordie but you should check both the quotes and article I linked. Einstein did not geometrize SpaceTime. As far as I get it he tried to unify EM and gravity into a 'field', observer dependent .He was not happy with people thinking of SpaceTime as a geometry. So the discussion is slightly out of rails I guess, if we want to understand the way he thought about it :)

"     Dennis proceeded to a detailed account of what Einstein did think he was doing in general relativity. In brief, it was all about unification. In Einstein's special theory of relativity, we learned that the apparently distinct electric and magnetic fields were really just observer dependent manifestations of the one entity, the electromagnetic field. What for one observer might look like a purely magnetic field may manifest for another as a mix of both electric and magnetic fields.

It is the same for motion in general relativity. What may appear as motion in a gravitational field for one observer may manifest for another as gravitation-free motion. This was the real import of Einstein's famous elevator thought experiment and his principle of equivalence. Gravity has not been geometrized. It has been relativized. Inertia and gravity are unified in general relativity. Einstein's research trajectory then leads naturally to the focus of his last decades, a unified field theory that would merge gravity with electromagnetism.  " by John D. Norton

I suppose, or if you like, at least suspect that the 'fifth dimension' he looked for later was to find a way around observer dependencies, to unify those too into one 'field'.

[yor_on]

Acceleration is differing from a uniform motion in that it isn't frame dependent .Earth can be seen as accelerating at one gravity and so when you stand on a scale, you actually prove that acceleration.
=

Maybe a better way to express it is that it (a acceleration/deceleration) is locally provable, as well as locally unchanging no matter what frame of reference you use, whereas a uniform motion is dependent on what frame of reference you use to define it.