This is a question I've always had about the conventional explanation for gravity... I read something recently (either here or elsewhere) that reminded me of it, and it still puzzles me, so maybe you guys can shed some light on this. The conventional relativistic explanation of gravity goes like this: Imagine a stretched out rubber sheet; this is space-time. Place an object on the sheet and it will deform and curve downward in accordance to the shape and mass of the object; this curvature in space-time is what we call gravity. If we place another object on the sheet near the curvature, it will fall down the curvature 'well' towards the initial mass; this is analogous to the mechanism of gravitational attraction via curvature of space-time. Now, what bugs me about this explanation is that in some respects, it begs the question-- that is, in trying to explain how gravity works in the model, we are using a demonstration that depends crucially on our intuition of the functioning of gravity in the real world. Now, I suppose we could superficially get around this by conducting the demonstration in outer space, using metallic objects and replacing the downward pull of gravity with the downward pull of an appropriately situated magnet. But this is still presuming the existence of an attractive force to explain the mechanism of an attractive force. Anyone care to clear up the confusion?