In a further attempt to understand the time frames and two worlds of LOST, the above chart was created to help identify when and where the main characters were alive in the series. An early theory was that no one survived the plane crash (and the show was all about lost souls in purgatory). At the end of the series, the sideways world turned out to be an after life realm so initial indications of character deaths was nearly confirmed. Since the Sideways world was absolutely identified as a place of death, there are three time signatures in that world: when 815 "landed" at LAX, the last 7 days those dead souls lived in their sideways world, and the church reunion.
Then, comparing the four major time zones (the crash, the time skips, the O6/island disappearing time travel and the post-Incident/time returns to normal) in the island chronology to the sideways compressed time sphere.
If one supposes that the characters all died in the plane crash, then the two worlds are merely dream sub-sets of lost dead souls.
If one supposes that the characters did survive the plane crash, then one can imagine that the island characters were "alive" during the critical final 14 days of island existence (which is about 7 days run time in the sideways universe).
But things get confusing when looking at the major island time events. When Desmond used the fail safe key and the Hatch exploded, imploded, it is unclear whether anyone survived based upon the fact Desmond should not have. If Desmond's appearance after the Hatch destruction was his dead soul manifested as a whisper or a smoke monster or a lost soul, then were the other main characters also dead? (If Desmond was dead at that point, but living with living beings, is this why he was able to awake first in the sideways world?)
Then, there was the major event when the O6 were in the helicopter and saw the island disappear. Did that mean everyone on the island was dead? It certainly looked like it. The same was true when the freighter blew up. And then, there is the possibility that when the helicopter was ditched in the ocean, the passengers did not survive so the Penny rescue was another Desmond fantasy or dream. So at this point in the island time line, it is unclear who is alive or dead.
Likewise, the post Incident 1977 jughead/construction site implosion would have had the same effect on Juliet as it previously did with Desmond. She should not have survived. And the people on the island, ripped from various space-time locations, would likely not have survived either (because the emotional cure of having a "constant" would likely not overcome the laws of quantum physics). But if one believes that the characters could have survived this time reboot, then there is the final ambiguity.
If people were still alive on the island, such as Ben, how could he be "dead" in the sideways world. How could any character who was still alive on the island to the very end, like Jack, be concurrently "alive" in the dead sideways world? Logically, one cannot be alive and dead at the same time. Christian's excuse that the sideways world is only "now," with no past, present or future time, is a white wash explanation that explains nothing.
It seems like the final 14 days on the island, after allegedly three years after Flight 815 crashed, are the most important part of the time inconsistencies. The strongest arguments could be made that the characters on the island were still alive, but someone the events of the first 7 days "created" the entire sideways matrix - - - an alternative, complex world with characters in totally different lives, careers and situations in minute detail - - - which again makes little sense if the trauma of the final days of island life was the last thing the characters would have remembered before their deaths.
