Recursion model of time travel is an alternate way to understand or explain the events in the Terminator franchise regarding time travel. The two major schools of thought to explain time travel in Terminator franchise are
- Predestination paradoxes occur, where something happens in history which could not occur without involvement from the future, and this past event lead to the event in the future that caused the past event to occur. The primary example of this in Terminator movie, John Connor exists in the future, and sends Kyle Reese back into the past, in order to become his father.
- The second theory is divergent timelines and alternate futures, where the idea is that all stories are interacting at once and can continue to change the past. Rather than this particular future then "ending", it continues on and events can continue to unfold and change the past.
The recursion model of time travel states that one major event in the future changes one major event in the past, and then life plays itself out again in the new present to create a new future, where at some point, another major event, which could be similar to a previous choice or completely different, changes the past again.
Why another theory?
Time travel is often a confusing point for people enjoying Terminator franchise. Recursion model is offered as a simplification, which mirrors the entertainment structure of one film or television show at a time.
Recursion model can unite all the major works (Terminator 1 thru 3, the Sarah Connor Chronicles (TV), Terminator Salvation, and Terminator Genisys) into one simple, cohesive story.
Recursion model treats the future where choices impact the past as "in the past" for the purpose of story telling, making it easy to understand. So, at the start of the Terminator Film, it is explained that in the future-past, time travelers were sent to 1984. Now, we begin story in 1984. There is no direct interaction with the future, no back and forth time travel. The future simply becomes the past.
This is very important for telling a good story. The story is always told in the present, whatever year that might be. Any future choices causing time travel known to the characters in the present become past choices, in the "future-past."
While there may be a temporal war going on, cause and effect still has an ordering to it. Sending things back in time creates a new present where the story takes place, but characters in the now future do not feel impact of the changes in the new present. History has to re-evolve based upon new decisions to create a new future, and that new future is the one the characters are creating in the new present. This means that the characters' choices are impactful and every time the story recurses through time travel and characters can change significantly.
Consider after Terminator, we learn in Terminator 2 that Skynet is built many years earlier than in the events described in Terminator. Thus, the new Skynet that invents time traveler did NOT send the first Terminator back. That was a different version of the character, with a different past and a different consciousness. "Skynet 2" may be completely unaware of "Skynet 1" and its actions in the future-past.
Basics on recursive time travel
Time Traveler's Gambit
Every time traveler has a big dilemma: if he goes back to the past and changes the past to change his future, he might not like the consequences or changes reaped of those changes. Therefore, it behooves the time traveler to make as small or minor changes as possible in order to make the desired change. For example, killing one person is likely to be unnoticed in the greater scheme of the world.
Skynet is in a particularly difficult gambit. Skynet's creation and very existence depends on confluence of events regarding advanced technology and political will in United States in the first part of the 21st century. Therefore, Skynet by using time travel could prevent its own creation by meddling with the past. As a matter of self-interest and military victory, Skynet must encure its own existence.
Limited Engagement and First Three Films
Because of time traveler's gambit, Skynet used time travel only sparingly and in a single use during the events depicted in the first three films. Note that Skynet at the start of Terminator film, used time travel as a last resort after John Connor's army made a decisive victory.
The strategy of limited engagement is critical to the plot of the first three films. For example, a common question is, "Why doesn't SkyNet try to kill Sarah Connor's mother or her mother's mother? Why 1984?" The answer: to minimize the risk to its own existence, Skynet risks going back in time only to 1984 and not further.
After the first three films, Skynet's strategy to have limited impact in the past has failed. So it then adopts a new strategy: massive time travel.
Recursion Model to explain Major works
Terminator Franchise can be summed up in this short story. Notice how when time travel recurses, the present becomes a future-past to the new present.
(Prior to Terminator Film)
Somewhere between 1986-1995, Sarah Connor gives birth as a single mother to her son, John. (Kyle Reese was not his father.) He eventually enlists in the army and then leads a resistance war against the machines c. 2029. Major event: time travel is invented and used as a last resort weapon by Skynet to send a lone cyborg to murder Sarah Connor in 1984, and the resistance sends Kyle Reese as a single protector. Time travel recurses to 1984.
Now Terminator film begins. After Terminator, in the new future, Skynet is built earlier and starts the war with humans earlier. This time John Connor completes the same task as he did in the future past, he defeats Skynet militarily. The plot repeats with one lone time traveler for each side, except technology is far more advanced, raising the stakes. Time travel recurses to 1994.
The Terminator 2 film occurs. John Connor has the inside track on Skynet now, he is able to aggressively take the fight to Skynet and win sooner than in the most recent future-past. The story recurses where a less advanced Terminator than T-1000 is sent back.
Terminator 3 film occurs. Skynet changes its strategy. It decides to ignore the Time Traveler's Gambit and begin massive incursion into the past. This begins a time war. Time travel recurses.
It is unclear how many times time travel may have recursed prior to the start of Terminator: Sarah Connor Chronicles. The time war is going on. At the conclusion of Sarah Connor Chronicles, John and Sarah Connor travel to the future. This does not break the recursion model. We can infer that succeed (hurray for our heroes), but not until Skynet uses time travel again as a last resort. Time travel recurses.
This brings us to Terminator Salvation, where things are very different than in any of the "future pasts" we know of. Most notably, extremely advanced cybernetics existed in early 21st century. It is possible Teminator Salvation occurs in a recursion before Sarah Connor Chronicles. It does not truly matter, because what matters is the present struggle told in the movie. Time travel recurses.
(At this point it should be clear, the Recursion model is a writer's delight: they can change as many details as they want without creating inconsistencies.)
Finally, we come to Terminator: Genisys. There has been a lot of recursive time travel going on prior to this movie. Terminator(s) were sent to kill Sarah Connor as child, so this reaches further back in the past than in any previous stories. Kyle Reese is sent to protect Sarah Connor in a repeat of events from before the first movie. It is not clear how Recursive time travel can explain this. One possible explanation is that after Kyle Reese is sent back, Skynet counters by sending another Terminator back even earlier in the past to kill Sarah Connor as a child, which prompts the resistance to send her a protector. While details may not be clear, we can easily understand this film in the same context: future events create changes and new story unfolds.