I would think one can pick any frame of refrence one wants for a though experiment?e
They may not correspond to the “truth” but the certainly can help us to understand things better.
For example saying “but for the purposes of this debate that is complex and subtle and we can consider that there is an absolute reference frame that is something like Machian.” Doesn’t mean a bloody thing to me…
I’m absolutely certain that my 2 year old daughter is certain that the entire universe revolves around her. (And by golly I thinks she’s right!)
So if you could tell me where my daughter would be sitting, relative to her current postion here on earth, if she was at the center of the Machian absolute reference frame, it would be more useful in terms of understand your point (and then she could visit and for a while she would be right.)
I am afraid this view is scientifically flawed and the thought experiment of someone grabbing the earth is horribly muddled.
The fact is that any frame of reference located on the earth’s surface (a non-inertial frame) is different from an inertial frame. All forces in an inertial frame are resolved, but in a non-inertial frame residual forces exist; in the case of the earth, coriolis and centrifugal forces arising from diurnal and annual rotation. These forces can be easily measured. It is fallacious to reason from the correct premise that it is possible to perform an instantaneous mathematical transform between any pair of frames, to the conclusion that all frames are equivalent. When we say the earth spins on its axis and that it orbits the sun, we are saying something that is true and non-trivial - these are more than relative ‘point of view’ statements.
Mach’s principle states that the universal frame is measured against the mean of the stellar field. Debate stiill rages as to whether GR is Machian, but for the purposes of this debate that is complex and subtle and we can consider that there is an absolute reference frame that is something like Machian.