Terminator timelines theory

I like the Terminator franchise. I wholeheartedly agree with the more or less general consensus that Terminator 2 is one of the best sci-fi movies ever made.

Of course the movies leave quite many questions about their internal logic (especially related to time-travel and how it affects the timeline) unanswered, and they could be considered outright plotholes. On the other hand, it's a fun exercise to come up with plausible explanations for these potential plotholes.

I present here a graph of my theory of the four Terminator movies. The contents of the graph are explained in more detail in the questions and answers page.

I will consider only the four movies here. I won't consider the TV series nor the different video games and other works as part of the "movie canon" (although they could work as separate timelines, except that some details in them contradict my theory).

I make the following assumptions in my theory. They are explained in more detail in the questions and answers page.

• Every time anything is sent to the past, the timeline splits. Whatever was sent to the past ends up in an alternate timeline which does not affect the original.
• Ontological inertia: Even if an attempt is made to change a timeline, the events of the timeline will nevertheless gravitate towards the same events of the original timeline (or events which have an equivalent outcome will become more likely). In other words, significant events tend to be preserved, even if it means that they happen with a delay.
• For some physical and/or technical reason there are only a few narrow time windows to which anything can be sent back in time. These time windows are located at 1984, 1995 and 2004.
• Because of some physical reasons or technical limitations (eg. available energy) the earliest possible time window reachable from around 2026 is the 1984 time window. (As Skynet's own time advances, at some point it becomes impossible to reach the 1984 time window anymore, and the next available one is the 1995 time window, and so on.) The time window previous to 1984 is so far in the past that it's not reachable by Skynet.
• Likewise because of technical reasons (time travel energy requirements and available resources) only one terminator can be sent at a time.

The timeline graph

Click on the image for a larger version. Also a PDF version is available.

Some notes:

• The Skynet in the original timeline might also have sent a T-1000 to the 1995 time window, and possibly a T-X to the 2004 time window (when it had gathered the resources and developed the necessary technology to do that). The reason for sending the T-1000 to 1995 is the same as in the other timelines (to kill John Connor himself before Judgment Day). In this timeline 2004 is well after Judgment Day, but sending T-X anyways to kill John Connor makes sense because Connor is still not the resistance leader and not prepared for such a powerful Terminator.
• Likewise the Skynet in the 1984-timeline may have sent a T-X to 2004 for the exact same reason.
• Because of ontological intertia, all the Skynets in all the timelines send the T-800 to 1984, as well as the other Terminators sent "before" the spawning of the corresponding timeline. In the 1995 and 2004 timelines this probably happens later than in the original and 1984 timelines (because Skynet was created later). However, it doesn't happen so much later that it would miss the 1984 time window. These time travels create alternate timelines, not seen in any of the movies.
• This happens eventually also in the 2004-timeline, but this is not marked in the graph because the current timeline "head" is at the fourth movie tag (so sending the Terminators back has still "not happened").
• The numbered "movie" tags are, naturally, Terminator, Terminator 2: Judgment Day, Terminator 3: Rise of the Machines and Terminator Salvation.