Remember back when we our cast spread over two different eras? Yeah, that was kid’s stuff. We apparently have two different realities now! This is something I suspected back last season, but we have verification now. As seen in Fantastic Four comics, the Back to the Future trilogy, and Sliding Doors, what happens when you change the past is that you create a separate timeline. See, if Flight 815 never crashes, then Jack and the rest never end up on the Island to detonate the bomb, which means the Swan Station is built, and then Flight 815 crashes. Which allows Jack to set off the bomb that prevents it from crashing. It’s a paradox, and it would seem that Lost takes the position that you can’t change your own past, but you create a split in the timeline.
