Point of order. Einstein didn't have a different theory of gravity. He did however, through relativity describe how "Newton's bucket" was no longer a conundrum. The laws of mass and attraction still hold. Newton did not question steady state and absolutism, hence Einstein's simple relativity was all the more profound.

it is the reason for gravity that is being refined. Newtonian physics are constantly refined as indeed they should be. A copy of the Principia I had when doing research into mechanical vibration is a hell of a lot thinner than the copy Mrs Musket bought me last year, as the appendixes concerning refinements and impact grow all the time. I especially like the citation on page 923 of appendix 4, but I digress.