A new theory doing the rounds of what is Lost is the Time Loop Theory.
Sounds quite plausible and seemingly coherent. Key Quote
Basically, the “rules of the time machine” are not governed by any physical definitions of time travel. The “rules,” if you will, are governed by how FATE decides to preserve the timeline. Thus, if you are required to do something profound in a future timeline, fate will find any way possible to preserve the timeline – we’ve seen ghosts and smoke monsters in LOST. So according to the show’s definition of time travel, fate “does have a funny way of course correcting.”
So even if we could travel back in time and managed to change something, fate would intervene in some form or another and set things right.
If you replace Fate with Physics it would be consistent with the view that time is simply an illusion an artefact of point of view and at a fundamental level there are simply interacting wave-functions correlated to each other.
It is not reality that has a time flow, but our very approximate knowledge of reality. Time is the effect of our ignorance