In the next examination of the popular theories prior to Season 6, a lesser viewed notion that the series was about the Island as a mothership.
This theory ties in with the deep American notion that the Rosewell UFO story was true. And plays into the conspiracy theories that surround most government dark projects.
This theory speculates that the island is not an island. We know that the island does not act like a Pacific land mass: it moves, it cannot be seen from the air, it can disappear without displacing a gallon of ocean water, it moves through both time and space at different rates than Earth.
It was called a "snow globe" by Desmond because those on the island could not go through its outer invisible barrier.
Further, the high tech science experiments conducted on the island further bolstered the notion that the supernatural elements inferred that a supernatural race of beings were controlling everything from behind the curtain. In Star Trek, the episode called "The Cage" explored a superior intellectual race viewing human behavior by capturing several star ship crew members to observe human behavior. Likewise, some speculate that the "coincidence" that all the 815 passengers had past connections and/or common personal issues too good to be not forced together by a third party.
As a result, the main characters were “Abducted by Aliens.” The island is not part of Earth. It could be cloaked in a stealth mode between our time and the alien's time. The survivors may no longer on Planet Earth, as the island is a space ship that re-creates Earth like a holodeck, so the aliens can take back these human beings as examples for further experimentation, or be part of an alien collection such as a zoo exhibit.
The smoke monster, as a high tech alien security system to keep the exhibit pieces on the island, is an explanation for the strange events on the island. It would appear that all the Dharma stations could have been set up to keep the human captives "busy" and pre-occupied so they don't realize that they have left their own solar system.
Early in the series run, Damon Lindelof shot down this theory. “There are no spaceships. There isn't any time travel,” he told Sci-FiWire.com. However, he also indicated that there was no purgatory, but the cast wound up in purgatory in the end. The series also featured both mental and physical time travel by various characters. The showrunners have always been inconsistent with their defense of the series against fan speculation to the point of being obstructionist. Again, there would have been nothing wrong with a premise that the 815 survivors were "captured" by aliens as the plane was about to crash into the ocean and teleported to their island cage for human behavioral experimentation. In fact, such a premise would actually lead the characters to rebel against a "real" foe instead of the illusory Jacob-MIB stand-off.