I searched for the definition of frames in relativity because I have seen FE explanations that talk about frames:
A “frame of reference” is a standard relative to which motion and rest may be measured; any set of points or objects that are at rest relative to one another enables us, in principle, to describe the relative motions of bodies.
When I learn about FE models, the most popular is the dome. Far as I know, there is no observation or explanation, possibly no way to know what lies beyond the inside of the dome. The UA theory says we are accelerating, which implies a location outside the dome to measure acceleration relative to. Incidentally, lucky us that the acceleration is not in the opposite direction, or we would be pinned to the dome looking up at thew earth's surface.
Seems to me that in FE models, there is only one possible frame. Most popular is the dome model, its own frame that includes nothing beyond it. My question is whether there is a FE model with multiple frames, or is the frame relativity theory wrong/nonexistent, or what?