Another thing you have to realize is in order to have a point of reference to whether up and down exist, you have to factor in the fact that everywhere in the universe is the center of it. You can never claim that you are facing up or down or sideways. The earths gravity pulling you towards it's center doesn't mean my up and down are the same a yours...maybe we can agree that the notion of up and down are relative to the person uttering the words "am facing up"