Mustrum_Ridcully said:
But this would immediately cause a paradox, as nobody needs to go back now to make Sylar feel special. Sylar must at least become a serial killer for anyone to have a reason to use time travel to stop him from doing something worse.
I think that might be the problem future hiro has encountered with his time travel (maybe that's what causes time rifts he talks about when he asks Peter to "Save the Cheerleader")
That's my theory on the limits of time travel in the show. We'll see if that holds.
Nature fills a vacuum immediately by an inrushing of the matter surrounding it.
Time and space are essentially the same thing, or facets of the same thing.
A time-paradox is like a vacuum in time. Since no new events would be created, events as they stand, slightly altered by the "inrushing", would still be accurate until something so massive occurred that some totally-unrelated event had to fill the hole in time.
Basically, Sylar could be made into a model citizen, killed at birth, or turned into a monkey, and the people who were directly related---as in taking the actions that changed events---would still remember, unless it caused such a massive inrush of events that all of history in that moment were completely altered.
The same would be true of anything that was changed, regarding the people/events that caused the change.
EDIT: I submit that Claire didn't die in the locker room because she didn't die in the locker room. It was what happened, a la future Hiro's timeline, but he only changed the particulars by warning Peter, not the actual outcome. Some more massive, and altering action was needed to prevent the destruction of NYC, such as killing Sylar, etc. Hiro might have opted for the less-intrusive option simply because he was afraid that all of time would implode trying to correct the change in a viable way.
Also, New York's destruction was a catalyst, not the end of the world, itself. The worldwide ramifications are just beginning to be felt in the Five Years Gone episode. There's more to Claire's living than just regeneration of whomever blows up. She needs to be saved in the future, as well; her power or her presence is somehow key to world events.
Just brainstorming. I hate it when lightning comes out of my ears.
