Zombipanda
My Boom-Boom's mostly gay
yeah, we find out that Jacob has been behind the scenes influencing the lives of the losties for years. So presumably the island being blown up removed Jacob's influence and their lives unfolded in slightly different ways.
*nod* Yeah. I follow. An the reflections in the mirror are the point of intersection that causes the divergences in the timelines, which is possibly why the Losties never saw the lighthouse when they were staying in the caves before but they can see it now, after the timelines diverge.
I wonder how Jacob was supposed to be contacting the new arrival (121, I think?) if he's dead.