Why doesn't anyone question the theory that gravity is the curvature of space time? It's pretty silly if you think about it. Space curves around an object but what is it that moves other objects towards it? The gravity? It is circular reasoning.
Also, think the curving of the space-time would only bring objects closer together once. Space does not curve indefinitely towards the object of greater mass, but only once. However, objects are CONSTANTLY attracted to it. Which implies a constant energy. Where does that constant energy come from? Relativity doesn't explain it.