Spirit World by Chemoboy

Every time, I think of the lighthouse it reminds me of a spirit catcher or at least what I imagine a spirit catcher is.

I know the island is not purgatory, but what if the body and soul lived in two separate places but were thinly connected to each other. The soul world (where our Lostites have operated) and the physical world (the ALT as it has been named). This could explain the sense of deja vu that our travelers experience.

The island is essentially the heart of the spirit world. The lighthouse acts as a way for Jacob to see the physical world. This spirit world is not bound to the all the laws of physics (time travel, island travel), would explain how people off island were 'magically' restricted from hurting themselves, and how the dead still seem never really stay dead.