Originally Posted by BagginsKQ
Why ignore 60 years of Star Trek time travel mechanics? I.E. if you change time, your previous timeline ceases to exist/paradox created, I.E. City on the Edge of Forever (Original Series), Yesterday's Enterprise (TNG) or Past Tense on DS9, etc, thus the need for Temporal Prime Directives, and an agency that monitors for changes in the timeline?)
You obviously don't watch enough Trek. The TNG episode Parallels explains the concept that "anything that can happen does happen in alternate quantum realities."
In that episode, Worf was being pushed from one alternate timeline to another to another. Also, this parallel universe concept is used with regard to the Mirror Universe
which was introduced in the TOS episode Mirror, Mirror
and was used in various episodes of DS9 and ENT.
Also, you cite Yesterday's Enterprise as evidence of time paradox, but The Enterprise-C didn't go back in time to prevent a paradox (as everyone considered that it should stay until Guinan changed Picard's mind); rather, they went back because the Klingons were about to win the war--a war which the Enterprise-C could have entirely prevented in the past by returning to fight at Narendra III. Similar said for City on the Edge of Forever
and Past Tense
. These episodes aren't about preventing paradoxes, but about restoring the known universe to the timeline which the time-travellers are familiar with.