You cant go back Lex!!! To go back, you would have to change the entire system back to an earlier configuration....... Where are you going to do this from if you are 'INSIDE THE SYSTEM?'..... You would have to be outside of it, which would mean you'd need the entire systems energy and more, an you cant have more than the system, or be outside of it, because, as Mr. Sagan said, the cosmos is all there is, all there ever was, and all there ever will be....... Infinity is all encompasing, and there can't therefore be anythimg outside of it or it wouldn't be 'ALL ENCOMPASSING......'