Contrary to what you may have heard, Newton’s theory of Gravity was NOT killed by Relativity Theory.
In Newton’s view of the Universe, a directly undetectable substance called Ether permeates much of Space. When Matter is present, it partially displaces this Ether field. To say another way: Ether is less dense inside Matter than outside of it. Due to this pressure differential (and we assume here some sort of Ether “pressure”), Ether is continually flowing from the area of greater density (outside the Matter) toward the area of lesser density (inside the Matter). This flow of Ether influences other objects in the Ether field (which are simultaneously creating their own systems of Ether differentials) to move toward the Matter, drawn by the Ether-currents.
It is held by many that we’ve moved past the old Newtonian Gravity and now have Relativistic Gravity. However, there is nothing whatsoever in Newton’s view of Gravity that is at variance with the outcomes of Relativity. Einstein conjectured that Space, itself, bends toward Matter; Newton said it’s the Ether moving toward Matter. Either way, objects are influenced toward each other– as if Space curved toward the object– as if Ether flowed toward the object.
Some will argue that Relativity takes into account the essence of Time (whatever that is), whereas Newton’s Gravitational theory does not. However, I believe that Essence Of Time theories can be separated-out from functional Gravitational theories; for instance, we might have multiple, working Gravitational theories, and one Time theory that can overlay or parallel each Gravitational theory. I don’t think that is a bad idea at all– I mean, our brains have a hard enough time grasping concepts pertaining to the cause for Gravitation, but we are completely out to sea when it comes to thinking about Time.
Additionally, I’m not convinced that we have actually proven beyond doubt Einstein’s theory about Time (yes, I’m familiar with the clocks-in-space experiments).
And theoretically speaking, Einstein’s Time “Transformations” were not something he deduced from observations; Einstein had no choice but to include Time Transformation into his theory of expanding-and-contracting Space to keep his interconnecting conjectures logical and internally consistent. So what he did, he lifted, variable for variable, the Time Transformations that Lorentz had come up with to go with his own theory pertaining to the Distortion Fields created by Moving-Charged-Objects (I contend that Lorentz completed 75% of Einsteinian Relativity theory before Einstein was even out of school].
One thing some people will point-to when they want to dismiss Newtonian Gravity is that Newton contended that Light moving past a heavy object will bend AWAY from it, whereas Relativity predicts it will move TOWARD the object, and that Relativity turned out to be right (they’ll mention a solar eclipse in the late 1910s). However, this is a case where we should not allow a theorist to interpret his own theory. In truth, Newton’s Gravity has no problem whatsoever supporting the view that Light would bend toward a heavy object like the sun on its way past, for Light could be affected by the Ether similar to how Matter is.