Originally Posted by
Aerith's Knight
According to the multiple reality theory set by Einstein, you wouldn't need to visit the past, because this would merely make a new reality, and why go through all that trouble when you could hop to another reality that has everything you want (and within infinite possibilities, there will be one where you have what you want). I'm assuming that since you have power of space-time, a simple reality jump won't make that much of a difference.
But personally, I think time is more like a jigsaw. You can go back, but all the changes you made will already have been done when you leave. It all fits together, like a self-fulfilling prophecy.