I'm familiar with the differences between Relativistic physics versus Newtonian, and you're right, Newtonian physics works perfectly well except in high gravity fields, generally stellar masses and above. I'm not all that familiar with quantum physics, I admit, but I don't think there's all that much of an effect on a macro scale. More reading for my list, I suppose.
More reading for me! I'm not up on the effects of gravity waves, and planets moving in the troughs. It seems to make some sense, if indeed gravity is wavelike in nature. I'll have to look into it more deeply, when I can get the time.Now when the sun transitions to red giant status, its gravitational aspect will change, the allready existing pressure waves that act like troughs in the fabric of spacetime that the planets orbit within...will also change. Theorehtically unless there is a mass ejection wave none of the planets should get swallowed so much as shoved out as their orbitale trough moves.