original_query: What is the significance of "LA X" in the context of the television show Lost?
query: What is the significance of the episode "LA X" in the television show Lost?
answer: "LA X" is the two-part premiere of the final season of Lost.  It introduces a new narrative device of two separate timelines (referred to as 'flash sideways'), replacing flashbacks, flash-forwards, and time travel. One timeline depicts Oceanic Flight 815 never crashing, while the other follows the events after the hydrogen bomb detonation in the previous episode.