If this something temporal has its origin in the future, then there might have been a timeline where there was never a rift, and the Enterprise-C never came to the future. In fact, this is exactly how the episode plays it.
In fact, if you look things through down to the nitty gritty, it could even be, that there was a timeline with only one Yar.
...The same rift remained open the entire time, and the Enterprise-C (with Lt. Yar aboard) returned through the same rift to its same past timeline where it had disappeared from. So there were only two timelines depicted in that episode, and the rift connected both of them. And both timelines were identical up until the point where Lt. Yar went back in time on the Enterprise-C to create the new timeline.
Since we saw the rift in all timelines, you can't argue that there was a timeline where there was no rift.
I understand your point here, and the last sentence sums it up cogently. In both the "war" timeline
and the "no war, double Yar" timeline, the existence of a rift is a known (indeed, essential) element of the past at the time of the ENT-C's battle.
The fact remains, however... and I don't want to be didactic, but I think it bears repeating... from the point of view not only of the viewers but
also of the characters in past and future episodes, everyone proceeded smoothly from a pre-rift past to a war-free future. The only oddity in this progression of history is that at the time of the battle the ENT-C briefly disappeared into, and then returned from, a rift that took it into what is (again, from this timeline's POV, but it's a legitimate one) an alternate future.
Yes, in a hypothetical timeline where there never was a temporal rift, then there would be no Klingon war, Lt. Worf would join Starfleet, and Yar might be killed by a tar monster. But in this hypothetical timeline, nothing would ever create a temporal rift, so there would be no time-traveling Yar on the Enterprise-C, and she would never have a half-Romulan daughter. Obviously, this hypothetical no-rift timeline is not the one depicted in "Yesterday's Enterprise" or any other episode...
On the contrary, I'd argue that it isn't hypothetical but is the timeline depicted in every episode of TNG prior to "Yesterday's Enterprise." This is the no-war, single-Yar timeline.
Then (and I use the word with hesitation, not meaning to imply chronology) the rift comes into existence at the critical "past" moment, causing the branching into (on the one hand) the war timeline and (on the other hand) the no-war, double-Yar timeline.
Just like in "Star Trek Generations" when Picard used the Nexus to go back in time and create a NEW timeline where the Enterprise-D crew did NOT die, and the sun did NOT explode, and he did NOT enter the Nexus. ... These are all alternate timelines (as opposed to the "original" timeline), but we, as TV viewers, "care" about these timelines created by time travelers, while we don't "care" about the original timelines the time travelers came from, since the "Star Trek" series does not depict those "original" timelines from week to week.
You can call them "original" if you want, but the fact remains that in most cases (including these examples) they seal themselves off via time loops by preventing their own creation(s) and thus have, quite literally, no future. And, yeah, they also tend to occupy no more than a few minutes of screen time.
The timeline that viewers care about, though (which is hardly deserving of the dismissive quotes, as it's of crucial narrative importance!), and which moreover is experienced as an unbroken sequence of events by the characters (at least most of them -- e.g., everyone except Yar in the "YE" example, everyone except Picard in the "Generations" one),
does in fact continue on into an ongoing future.
Yes! I'm proposing a Logical Pretzel™! You've brilliantly summed up in two words what I wasted thousands of words trying to explain.
Well, at least we can maintain a sense of humor about this.
There is no point at which the timeline incontrovertibly backs up and starts in a different direction, like what we're being told happens in this movie.
I think with that last sentence you just negated your own argument. Starting the timeline in a
different direction is ALWAYS the point of changing the past. (At least in "Star Trek Generations," "Yesterday's Enterprise," "Endgame," and a half dozen other episodes -- excluding causality loops like "Times Arrow" and "Parallax.)
Okay, let me clarify: a different direction from what we the viewers (and, in story, the characters) have grown familiar with over a significant period of time... as opposed to alternatives that are seldom experienced for any longer than necessary to drive home the point "oh no, better avoid this!"
(If "Yesterday's Enterprise" had not "corrected" history but had instead continued on into a Klingon-war future, for instance, I suspect that rather than being a favorite episode of many fans it would be widely loathed.)
In the case of this movie, that "significant period of time" in question (that we've come to know, but which is now being sidelined) is in fact the
entire history of on-screen Star Trek.
It's all subjective -- it's the point of view of the cameras showing us one timeline rather than an infinite number of equally real timelines. ...the difference is just the amount of time spent watching a series of events on our TVs
Subjective, yes, but not
arbitrary. There are powerful narrative reasons for sticking with the timeline we "know," however many zig-zags it may have (when seen from the outside) due to various chronal incursions.
Regardless of which timeline one chooses to consider "original" given a certain interpretation of temporal mechanics (and in the case of this film, from what we know it does appear to be our familiar one), the choice to shift focus to an "alternative" presents a significant challenge to audience sympathies.
In terms of logic and causality, the new movie is not doing anything different from other time travel stories in "Star Trek." The only difference is our emotional reaction to it, since, for the first time in a time travel story, we care more about the timeline the time traveler is coming from than we do about the new timeline the time traveler is creating.
But that's exactly what it
is doing differently: it's sticking with the new variant timeline
rather than restoring or returning to the familiar one (or some very close variant thereof; e.g., two Yars). Are you suggesting that because the plot logic is otherwise familiar, people should be willing or able to set aside their emotional reaction to this difference? IMHO that's a pretty damn crucial difference.
Let me sum this up in the form of a question: why should we be quibbling over details of temporal logic, when what viewers "care about" is
so much more important?
