My understanding of the "rules" of time travel
The Logic Part
- Whatever happened happened is the fundamental principle of the universe, i.e., events that have already occurred are unchanging.
- Whatever happened happened also means whatever happens happens and whatever will happen will happen. Events were, are, and will be. With the amount of destiny talk on this show, this viewpoint shouldn't be surprising.
- DHARMA seeks to find an exception to that principle, as evinced by the Sri Lanka Video1.
- According to the Sri Lanka Video, the Valenzetti Equation "predicts the exact number of years and months until humanity extinguishes itself."
- DHARMA is attempting to change key numbers in the equation in order to change its outcome, i.e. the future.
- If time is fundamentally changeable, DHARMA would not need to research a method to change it. Any action they perform in the past could be capable of changing an outcome.
- They are spending a great deal of time, money, and resources toward finding how to change the equation. To go to those lengths implies their belief that they can change the equation.
- Events will not be changed by individual moral decisions or impulses, e.g. shooting a young Ben. However, through extensive research, someone may be able to change a specific event or events by successfully manipulating "the core environmental and human factors" of that event.
The Speculation Part
The obvious candidate to successfully change those variables seems to be Daniel Faraday.
Faraday, as early as his first flashback, seems to have some kind of foreknowledge or awareness that he can't quite grasp. He cries about the loss of people he has not yet met, and can't understand why. He appears surprised to find a note he wrote to to himself in his own journal.
His knowledge of Desmond's "specialness" and identity as Daniel's own constant imply that Desmond will be of significance when Daniel unravels the equation. Perhaps Desmond himself is one of the numbers in the equation, or he simply has the ability to manipulate one, or all, of the variables.
Either way, I think we will go on this season or next to see that time can be changed, but that a very precise set of factors need to be fulfilled to do so. Whatever the change, it will be deliberate and much labored over, not incidental.
1. Note that the producers consider the material presented in this video canon. It's background information that doesn't have time or precedence to be shown on air, but is a valid part of the LOST plot line.