This is not a mathematically supported proof or a detailed one, but rather a philosophical proof, being my (temporary) conclusion of https://www.physicsforums.com/showthread.php?t=404650". To sum up the initial problem, there are two bodies in space rotating about one another, attracted by gravity, and held in equillibrium. Why do the bodies not collide at the same rate as if they were not rotating about one another? This seems like a simple problem, however the problem is not a question of simple Newtonian mechanics, centrifugal force etc. but involves references frames, particularly non-inertial reference frames. The details of the problem are at the link above. The rotating bodies not colliding prove that objects interact with spacetime, because it is the interaction of those bodies with spacetime that prevent their collision. First I thought, well the difference is in all other objects around them, even being at the vast distances they are, for that is the only difference between two bodies rotating about one another and bodies not rotating about one another. So then this fake centrifugal force is caused by those objects swirling around them, at gravitationally negligible distances away. However, if this is the case, then that means we could induce fake inertial forces on objects by swilring around them, and we know this is not the case. This leads us to one conclusion, that spacetime has underlying mechanics of its own, and that physics does not just deal with the interaction between objects, but even interactions with spacetime. A few things I'd like to mention, is that I don't say anything about how matter interacts with spacetime. Also, when objects are rotating about other objects/spinning/revolving, they perceive EVERYTHING else as swirling around them, this could be a requirement for the fake forces we see in "non-inertial" reference frames, and that just our influence alone on an object in an attempt to induce a fake inertial force is not enough, it requires the movement of all the rest of the objects in the universe. Nevertheless, I still believe, based on the above logic, that objects interact with spacetime. I find this interesting because I have never learned of physical laws that involve interactions between objects and spacetime.