MIRROR, MIRROR
Let's begin with the former possibility that there are two (or more) mirror timelines. That's the premise of my theory When Alternate Realities Collide, in which I suggest that the Island is basically a conduit between two realities, light and dark. Under this theory, the first Incident could have involved scientists making mental contact with their "twins" in the mirror reality. The analogy here is to Desmond, who may have crossed minds with his twin in an alternate time-line during S3E8, much like the son in the film Frequency makes radio contact with his father in an alternate timeline. In the case of the Incident, the Swan scientists made psychic contact with their mirror reality twins, drawing them to the Island.
One of the first may have been Dr. Mark Wickmund's counterpart, Marvin Candle, who landed on the Island and lost his arm in a confrontation with the Cerberus security system. After some confusion, the scientists realized that the two timelines were beginning to merge via the Island conduit. In an effort to preserve both realities, Dharma became an experiment in whether people drawn literally from different worlds could co-exist harmoniously. The Linuses were among the first of these test subjects, though it's possible that some of the people who arrived with them had twins who were already present. This could explain why, as a poster named Dark UFO notes, some of the same people seen exiting from the submarine are glimpsed shortly thereafter in the Barracks Orientation Video.
To prevent further incidents, the Island was quarantined out of phase with both realities. Swan Station was redesigned to plug the leak from the electromagnetic anomaly, thus preventing the Island from reaching the critical energy level of "42." To deter one timeline from exploiting the anomaly to alter or destroy its counterpart, Swan was staffed by representatives of each reality. The containment device itself was sealed behind a thick concrete barrier to discourage tampering. The Numbers protocol was the ultimate insurance policy, offering both sides powerful incentive to continue staffing the Swan. Every 108 minutes, someone had to manually enter the code or the resulting implosion would destroy both worlds simultaneously. Think of the Doomsday Device in Dr. Strangelove...
A SOUND OF THUNDER
So what about the possibility of a single timeline? Under this theory, the first Incident may have hurtled the Swan scientists temporarily back through time like Desmond following activation of the Fail Safe. Though the scientists made only slight changes, their cumulative effect on the timeline was still profound. The analogy here is to the Ray Bradbury short story A Sound of Thunder, wherein the destruction of a single prehistoric butterfly alters the future dramatically for the worse. The story is meant to represent the so-called Butterfly Effect -- i.e., the notion that some systems are so sensitive that even minor variations in initial conditions can yield major differences in outcomes over the long term. As a poster named Lostmommy notes, the butterflies displayed on Ben's desk during S3E13 may well be a reference to the Butterfly Effect.
My guess is that the Island is somehow insulated from such alterations to the timeline. As with Desmond and the survivors of Oceanic 815, the Swan scientists may not have realized that the the outside world had changed until visitors showed up on the Island. My guess is that a delegation from the Hanso Group landed led by none other than Dr. Marvin Candle, who was previously known as Mark Wickmund before the Incident changed history. Tragically, the Cerberus security system failed to recognize Dr. Candle and attacked his delegation. This could explain why, as a poster named Mike NY notes, the Blast Door Map refers to "5 fatalities" near the Swan. Once everyone realized what had happened, the nature and purpose of Dharma shifted.
To prevent further alterations to the timeline (e.g., for personal reasons) Swan became a containment device that limited the Island's effect on past, present, and future. Dharma devoted itself to creating the kind of human being who could manipulate history responsibly. The hope was that some day, someone worthy would turn the Fail-Safe key, sacrificing himself to save everyone -- i.e., the Dr. Manhattan Project. I like this particular angle because it resonates with the themes of heroism that the writers have taken pains to emphasize of late. It also explains the elements of a psychological experiment that permeate so many of the Stations. It's entirely possible the whole purpose of the Pearl and Swan was to trigger another Incident, giving a true hero the power to save the world.
So that's my dilemma, fellow Lost theorists, and I'm eager to eat, er, pick your brains. If the choice is between mirror Spock or A Sound of Thunder, which do you favor, one timeline or two?
