Okay, this theory I do not think has been stated, so here goes. Yondaime had some sort of Space/Time Jutsu that allowed him to either Teleport, or stop time and go to wherever he needed to be, making it look like he teleported. Awesome technique we all can agree on that right? But why can't Jiraiya use it? Or can he and he chooses not to? Why cant anyone but Yondaime use this technique? Bloodline Limit anyone? Anyways, heres the punch line. If Yondaime could stop, or slow down time, wouldnt it be possibly to reverse time as well? What if Yondaime isn't Naruto's father at all, but is Naruto himself, but sealed the Kyubi inside himself and reversed time for whatever reason to an infant state. Which would explain why Yondaimes name was never mentioned, maybe his name is Uzumaki Naruto Just a thought I wanted to throw out and get opinions on.