If you can give me an example of a locomotive "entity" that keeps the earth moving through space at your "9.81 m/s/s", I'll never post here again
We can explain the specifics of our universal acceleration force no better than you can explain your universal gravity.
We see the effects of said force - mainly the earth's constant upward acceleration - but beyond that, the details remain elusive. Exactly like gravity in the RE model.
There are four, which are alot better than a turtle.
* The Schwarzschild solution, which describes spacetime surrounding a spherically symmetric non-rotating uncharged massive object. For compact enough objects, this solution generated a black hole with a central singularity.
* The Reissner-Nordström solution, in which the central object has an electrical charge. For charges with a geometrized length which are less than the geometrized length of the mass of the object, this solution produces black holes with two event horizons.
* The Kerr solution solution for rotating massive objects. This solution also produces black holes with multiple event horizons.
* The cosmological Robertson-Walker solution, which predicts the expansion of the universe.
And there is always
, where objects will be physically acceclerated towards the center of an object.
And there is even
http://en.wikipedia.org/wiki/Quantum_gravity