I am having difficulty understanding the statement "gravity propagates through mass without loosing power". I asked a friend about this and he replied that gravity is not a "force" that acts on objects. Its more like a curving of space. A rock rolls down a hill towards the "deeper" part of the hill, but the hill remains the same gradient, its effect on the rock doesn't change the hills shape. Sadly I am still not grasping either statement. Surely gravity is a force, a free body force diagram of objects of rest even indicate gravity as a force. And while I do understand what gravity can act on objects without loosing power, I cannot fathom the mechanics behind it.