The following is not a theory, but more like a thesis. An analysis of the elements presented by the creators of LOST in order to establish an unknown, unexpressed or clouded explanation for the premise of the show and its disjointed parts. To unlock the mysteries of LOST, which I believe have even escaped the minds of TPTB, one needs to find the Key. In the search for the Key, one has to first try to determine the core of the show's mythology.
If you have the same character in two different places, seemingly at the same time, how does one reconcile this issue?
We were shown characters in action simultaneously on the island and in the sideways world. Example, Jack: in the sideways world he is a divorcee (from Juliet) with a son. In the island world, Jack is a divorcee (from Sarah) without a son. In the sideways world, Jack is a doctor. In the island world, he is a doctor trapped on a crazy island. In the sideways world, his friends "are waiting for him." (Which many have assumed means Jack needs to "die" on the island to go to the sideways world.)
Except, this is not a clear rule. Charlie died on the island. Yet, his ghost physically interacted with Hurley at the mental institution. Yet, Charlie was one of the last to "awaken" in the sideways world, with the birth of Aaron. Which also leads to a problem: how can an alive Aaron in the island universe not be alive in the sideways world?
Likewise, why are certain principal elements different in the island world versus the sideways world? Sawyer was a police officer in the sideways world, not a con-man. Daniel was a musician in the sideways world, not a theoretical scientist. Widmore was a mean spirited murderous businessman in the island world, but a great affable boss in the sideways world. It appears that each character has two sides to their personal coin.
In the wake of the show's conclusion, no critic, show commentator, or show writer has tried to fully explain this fundamental story structural problem. By not explaining the conclusion relative to the prior seasons' settings, there remains a huge disconnect in the fan base. Some don't care because a happy ending is all that matters; others found it a cheap cop out. There has to be a solution to this dogma.
For the show to stand up to reasonable scrutiny, the core or story foundation must be able to explain the apparent inconsistent duality of the island and the sideways worlds.
FIRST, let us look at the title.
LOST. As an adjective, it is defined as follows:
1. unable to find one's way; not knowing one's whereabouts;
2. unable to be found;
3. very confused or insecure or in great difficulty;
4. denoting something that has been taken away or cannot be recovered;
5. "having perished."
SECOND, "perished" means: "death, typically in a violent, sudden and untimely way."
LOST opened with a sudden, untimely and violent beginning: a plane crash. A mid-air catastrophic break up at 30,000 feet. Chance of survival: nil. But viewers saw survivors on the beach. But how does that mesh with the Flight 815 sideways world time line? It does not. The sideways world is not a "reset" of a time line from the island world perspective. It is its own independent world.
THIRD, then reconciliation assumption is that the game board (story foundation) contains two independent worlds with some bridge (means to transverse) between the two.
So what "known" concept can explain the inherit difficulties of this duality?
Ancient Egyptian mythology.
The ancient Egyptians view on the human soul has been lost to the average person. As an early belief system to explain the role of man in the universe, the human soul was described in five elements to explain life. Egyptians had a philosophy of duality; that there was light and darkness, which worked in conjunction against each other to balance the world. The philosophy was filled with symbols, traditions, rituals, judgments and magical spells which can be found peppered throughout the LOST stories.
The ancient concept of a person was that he or she was made up or exist because of five elements present in that person:
1. Name (ren): every person has one; it was stated that "if spoken you'd continue to live." (LOST cue: MIB, a dead person whose name was never spoken).
2. Shadow: part of the duality of the universe; always within a person; it also protects individuals but also needs protection. (LOST cue: the Smoke Monster)
3. Ba: attached to the physical body, it is a person's personality; it needs nourishment.
4. Ka: described as the "life force" in all things; intellectual and spiritual power; needs a body after death in order to survive. (LOST cue: the light cave)
5. Akh: the unification of the soul elements; if ba and ka don't unite after death, a person "will die a second time."
When a person dies, their ba and ka separate. In the underworld, a duplicate body must journey through dangerous tests in order to find enlightenment, redemption and final judgment. If successful, the ba and ka will come together and reunite to create a new "body" in the after life.
Was not Jack's ending, with his friends and father waiting at the church for Jack to "awaken," or join his memories of the island time with his sideways being (a temporary construct) to create a "new" Jack? Jack's "Ka" was waiting in the sideways realm for his "Ba" to complete its journey in the island realm. With the unification, Jack was then ready "to move on" in the after life.
The best explanation for the apparent inconsistent duality of the island and the sideways worlds is that the basic building block for the LOST mythology is ancient Egyptian religious concepts of a person's spirit being divided at death to journey through tests in the underworld in order to reunite to live on in the after life.