In the episode "Parallels", Worf starts jumping around to different universes after going through some kind of quantum fissure while returning from a Bat'leth tournament. When he first started jumping, the changes were small, and increased more as the episode went on. Some of these universes could only have existed based on event outcomes/decisions made PRIOR to his first entering the fissure, e.g. the more militant Bajorans, Captain Picard killed in the fight with the Borg, etc. However, since he entered the fissure at the particular time he did, it would seem he should only be able to jump to universes created after that moment, not before. Thoughts?