I have a bar of metal 1 light second long and if i push it at one end it can not move at the other end until at least 1 second has passed because otherwise it would move faster than the speed of light. A .1 light second long bar .1 seconds later before the other end may move, and smaller and smaller and smaller etc., until finally we are the size of an atom. Does the same principle apply here? At subatomic levels such as a proton? Quark? Is this the cause of inertia or is it some other force that is manifesting itself?