I repeat X which I have suggested has speed faster than light & is capable of traveling between Universes which itself is against physical laws. Because one of the proposed theory of universe says that the edge of universe is so dense with electromagnetic field that even light cannot cross it. Dark energy is physical. It is a a form of energy which was formed as one of the many forces like strong force , weak force & gravity after the big bang. Dark energy essentially is a physical entity. And my 'X' factor is nothing of that sort.