Wonderful episode. One of my favorites, right up there with Six months ago and Company Man for me.
Lots of surprises, Nathan being Sylar got me pretty good.
Time travel can be very confusing. Here is my crack at it.
In the Future time the following happens:
Sylar kills Claire and gains her power.
FutureHiro tries to kill Sylar, and fails due to Claires power.
Sylar explodes and destroys NYC (originally it had to be Sylar, not Peter who was the bomb, more on that later).
FutureHiro goes back in time and tells Peter that if he saves the cheerleader, he saves the world.
Peter saves Claire from Sylar.
Sylar does not get Claires power, Peter does.
Peter has visions that he is the bomb.
Hiro and Ando go to the future and meet FutureHiro.
The fact that NYC is destroyed has not changed. (One could argue that FutureHiro could not change his timeline, due to the Paradox theory)
FuturePeter says that he was the explosion not Sylar.
Hiro and Ando go back in time to try to save the world.
A couple of things can be divulged from this.
1. Originally, Sylar was the one who was the bomb.
Peter originally couldnt have been the bomb b/c he didnt have Claires powers. Sylar killed Claire at homecoming before Peter could meet her. FutureHiro says that he knew Peter post NYC explosion. That means that Peter was not at the explosion or he would be dead.
B/c Peter stopped him, Peter became the bomb. This maybe due to the Paradox theory, that if FutureHiro were to have saved NYC, then NYC would have not been destroyed, and if it wasnt destroyed then FutureHiro would not have gone back to save it. If he did not go back to save NYC then it WAS destroyed and the loop continues. (Isnt time travel fun?)
Therefore the universe corrected the paradox and had Peter be the bomb. One could suggest that FutureHiro could never save his own timeline.
2. The second is that Save the Cheerleader, save the world is meaningless. The saying was brought to save Claire b/c SYLAR was the bomb and he had her power. With Peter being the bomb, saving Claire wont necessarily save the world. This all makes the situation more hopeless for our Hiroes.
Hope some of this makes sense.
-casusev
For wonderful time travel info:
http://en.wikipedia.org/wiki/Time_travel