Abstract: The author originally posted this at TrekWeb (link defunct 2018/01/02). The author takes the position that the continued existence of the original Star Trek time line is plausible within Star Trek canon, and that the argument that the events shown in the 2009 movie necessarily mean the original time line has been (narratively) obliterated is hokum. Word count: ±800.
Quote from StillKirok:
It’s clear that the intent was to have them be the same people. So it’s the same universe, overwritten. The movie itself shows that, has no differences in time travel than with previously established canon, and the only “hope” for the prime universe is comments that were clearly meant to appease hardcore fans but have no backing in the movie itself.
This business that the general principle of time travel in Star Trek is that it always endangers the previous time line is hokum. Call it overwriting, obliterating, replacing, throwing in the trash, what-have-you. It’s still hokum.
Sometimes, like in “City on the Edge of Forever,” it appears to. Appears to. Our heroes lose contact with the ship and the Guardian tells them what’s what. And they accept it because it’s consistent with their experience. Then they go back in time, figure out that when McCoy–off screen–prevented the death of Edith Keeler things changed, and that to fix them they have to let her die. Then, having let her die, they all get to come home, and things are fixed.
This interpretation–that a change in the past obliterated our heroes’ present, and that they fixed things by their actions in the past–relies on an assumption that the Guardian gave an accurate assessment of the situation.
On the other hand, we are faced with the time travel story in the movie called The Voyage Home. In that movie our heroes go back in time and make–on screen–at least four significant alterations in the time line. And these don’t include the incidental interactions the characters have (into which category I’ll even put the “Chekov’s arrest and surgery” subplot).
The first is when McCoy and Scotty give transparent aluminum to that 20th Century engineer. This is an incursion of advanced technology into the past. In the new movie the mere implication of advanced technology is enough to make major changes in the technology and design of things in the new time line. What changes in the future time line might happen with transparent aluminum available so many, many years before it was supposed to be? McCoy and Scott briefly wonder, but leave it to the side with a glib, “how do we know he didn’t invent the stuff?” We don’t, of course, know that he didn’t invent the stuff, but it’s a change in the time line even if he was ‘supposed’ to invent it when it appears on his Macintosh computer fully-formed in the late 1980s rather than as a result of years of development.
The second is when McCoy gives the dialysis patient a pill and she grows a new kidney. This is another example of the Edith Keeler problem. What was that woman ‘supposed’ to do as a dialysis patient? What will she do now? What changes to the time line might her no longer needing dialysis cause? How about the fact that she grew a new kidney? Might this lead to the early discovery of McCoy’s organ-growing pills? What changes might this early discovery cause?
The third and fourth changes occur at the same time, and are essentially additional examples of the Edith Keeler problem. Our heroes remove from the time line Dr. Taylor (#3) and the whales (#4). What might these beings not do now that they were ‘supposed’ to do before? It might be argued that the whales can’t affect the time line. I’d respond that clearly humpback whales (generally considered) are very important or that probe wouldn’t be there looking for them in our heroes’ present. It’s therefore possible that any individual whale might be important to the ‘proper’ unfolding of the time line, even if that importance is largely invisible to humans.
Yet, with all of these alterations to events–and remember that these aren’t ‘merely’ interactions with 20th Century people which could be shrugged off; these are actual material changes in the flow of events, changes caused by our heroes–when our heroes go home they end up… home. They even manage to pop out within a handful of seconds of when they left. The initial crisis for which time travel seemed a reasonable solution continues unchanged. There is no alteration in the time line. None.
My point isn’t that, within Star Trek stories, time travel cannot cause an existential threat to the time line, but rather that within canon there appears to be ample evidence that mere alterations in the time line do not necessarily cause the obliteration of the original time line. And the fact that our point of view changes (including both our POV as viewers, and the POV of our characters)–we were following one time line and now we are following a different one–does not have any implications for the continued existence (or not) of the time line we were following in the first place.
All we can say for sure is that, sometimes, time travel causes our heroes to become disconnected from their home time lines and that sometimes it does not. Because that is all we’ve really seen–on screen.