Originally Posted by Civbert

If you consider a rock that large, the definition of lift becomes meaningless. Objects move relative to other objects (motion is not absolute). Lifting is simply separating two objects of mass - the one so massive that due to inertia, it experiences no measurable acceleration relative to the other as they are forced apart. Consider progressively massive rocks on earth. At some point the rock either collapse into the earths crust, or it becomes a planet and the earth becomes the rock. This would apply to any other planet. If the rock is in space, there is no other rock to lift against. Objects so massive they can not be forced apart would not be identifiable as separate objects - it would be one object..