The hydrogen bomb exploded
in 1977, and SPLIT it into 2 PARALLEL time lines. In one, it sunk the island, instead of vaporizing it, and the plane landed in LAX, since the island was no longer there to cause the plane to tear apart.
Sayid's body= "light man/Jacob" most likely. As for what he and the "dark man" (now in Locke's body) is doing, it's called "Backgammon".
Backgammon - Wikipedia, the free encyclopedia
Simple as that... It came up in an aside, right at the very start of the series in 2004, when Locke tried to teach Michael's son Walt how to play it.. "Two players, two sides. One is light, one is dark... Walt, do you want to know a SECRET?"
YouTube- LOST - Backgammon (Season 1 - Pilot Part 2)
YUP, they gave away the
entire series on the pilot, and NOBODY realized it then!! Big joke on all of us!