Okay, I've seen Primer on DVD tonight. It's by far not my first time-travel movie, or time-travel fiction in general. I know all about immutable timelines and timelines mutable because with every change, you create a new universe.
But I have no idea how Primer is supposed to work, both in theoretical physics AND narratively. Actually, it feels like the director had a very good thing going but with only 10 or 15 more minutes to go, he realized that he had too many lose ends and no way to fix anything, so he decided to make the final 15 minutes just some jumbled mess without any sense or meaning to it at all, just throwing in some bizarre, non-sensical images and words to baffle his audience and then leave it all at that.
The only thing where the director didn't mess up was on the actual audio-visual level, which is the most basic skill in film-making. There were no grave mistakes in those areas, but nothing grand either. It was the handling of this most basic issue of film-making that actually kept me at it, whereas the plot was so full of holes there was more of a hole than any plot at all.
When I'd finished watching it, I immediately went to Wikipedia which I always do after a viewing in order to get answers on things still unclear. But the plot description didn't make any sense either, and I came upon this fan-made graphic which was the first hint to me that James Berardinelli was right when he said that only those people can like the film that don't understand it: https://en.wikipedia.org/wiki/File:Time_Travel_Method-2... I mean this chart basically says that time-travel is the same thing as death! "The original loses his existence in the loop". Just where the hell did somebody get that messed-up idea?
Then I went to the official website to the film, with its official forum, to seek some definite answers. After about three hours of reading through that forum, it became clear to me that none of the fans there had much of an idea of the most basic foundations of time-travel theory, such as that they were unable to grasp the concept of a mutable or an immutable timeline, of physics (the forum is plastered with weird statements revealed a muddled understanding at best, such as "Einstein's theory basically says that we all travel through time at the speed of light", I mean WTF?!), and often-times, their sentences don't even make much sense on a grammatical level. Not to mention the fact they often mention whole SCENES that I don't remember from this film but from others, or entirely mix up the order of scenes in this film.
I don't even wanna talk about the unexplained "Granger incident" where a mostly unrelated character suddenly turns up as a time traveller from the future even though the two protagonists pretty much vowed to each other to keep the time machine's existence a secret, and this mysterious time traveller even falls comatose from the very moment they encounter him, and he obviously comes from a future that no longer exists. I mean as I've said, I'm used to time travel fiction, and that seems a totally plausible thing to happen with time travel, even if you wanna add suspense to your plot by never fully showing the background from where that came from or why he went back in time or even give him just a few lines to explain what happened.
There's far worse plotholes to boggle your mind.
To start it off, how do the two protagonists figure they have a time machine at hand? They observe that things age much faster inside their box, so POW! It must be a time machine! Their reasoning for it is weird: They kinda argue that objects must be "bouncing back and forth" between the moment the object is placed inside the box, and the moments it's removed from it. Just how they get this idea just from the fact that things inside the box age 13,000 times as fast as outside of it is never explained, and to call it "creative thinking" is a very nice way of putting it.
So, what we've seen is a machine within which things age much faster. From there, we suddenly jump to the phenomenon that time runs backwards within the box, and thus, it really IS a time machine, in that time inside it runs backwards between the time you stepped in and some time in the past that it's been turned on. How this follows from the fact that things age much faster in it is not explained.
In fact, it would be much more logical to FIRST have them see that time runs backwards inside the box until the moment you've turned it on, then see that if they don't remove the object at the right time, it goes "bouncing back and forth" in time within the box. That would be a much more logical way of thinking for them than have them see a machine which ages things faster and have them conclude from that that it must be a time machine within which time runs backwards.
Okay, so you'll turn the machine on, then at some later time step in and you travel back to the moment you've turned the machine on. That means you can never go further back than when you've turned on the machine in order to prepare your immediate trip. There might be a very complex set-up where you step into another time machine that has been turned on even earlier upon your way out of one, but it requires very meticulous scheduling, planning, and preparing way ahead, most likely from the very earliest moment in time on that you wanna head back to. Not even the fact you have time travel on your hands can change that fact.
Anyway, it all boils down to that you can't go back any further than to the moment the very first time machine was turned on, and from what we see in the film, most likely nobody ever stepped directly from one time machine into another.
What we are shown very late in the film is that the one of the two protagonists that does the first time travel has a so-called "failsafe machine" set up, which is a time machine he started way before any other, never used it, and never told his friend, the other protagonist and time traveler about, so in case of emergency, he'll have a way of erasing everything that went wrong.
What is revealed towards the end is that his friend DID find out about it somehow. How? We're never told. Okay, I'm still with you, and you don't need to explain everything. So what does his friend do? He travels back all the way to the beginning of the story, obviously due to some ethics disagreements on what to do and what not to do if you have time travel. He replaces his own past self, but only to do what? To record his conversations with his friend, and THEN go back AGAIN, eliminate his SECOND self in order to become the THIRD self and FAKE the SAME conversations by listening to his recordings on earplugs.
I mean WTF? What for? Obviously to tell the past version of his friend that they can record everything and then go back to fake-repeat conversations with other people over and over by listening to their recordings of the conversations the first time around. The connection between that and trying to prevent the shooting of the wife of one of them seems vague at best, and the whole thing of this shooting seems so casual to the whole story that you have no idea what they're actually doing there, or what for.
It seems more like that the one guy who used the "failsafe machine" for some reason was trying to trick his friend into something. Trick into what? We'll never know. All we know is it leads into both friends repeatedly knocking their own former selfs out (really their OWN, future A knocks out past A, and future B knocks out past B), without the other one knowing, or us knowing why the heck and what for. Even though they're portrayed as trying to trick each other, they're only knocking out past versions of THEMSELVES, not of the other, or prevent them from doing anything. They're only preventing THEMSELVES from doing anything, not EACH OTHER. By this time, it's all such a jumbled mess, we don't even know WHAT it is they're trying to prevent or make happen. Nor did we ever know.
Not to mention the fact that they obviously did all this with a now seemingly infinite number of "failsafe machines" they had to have set up immediately every time they exited their last one. If you really think this through, there must have been huge fields of time machines pretty close to each other for both of them in the last changed or created universe (one more time machine in each new universe created with each new travel), and out of all of them, new versions of the same guy exit at pretty much the same moment. All that while it's explained at the beginning that it's basic time travel 101 to make sure you never bump into yourself (unless you wanna hurt your earlier self, obviously).
To top it all of, the idea of "using a box inside another box" is mysteriously named as central to this whole weirdness. I don't even know what that could be good for. It still can't change the fact that you can't travel back any further than to when you've turned on the outer box, so what use could "a box inside a box" ever be other than make some obscure, non-sensical, and non-relevant reference to those Russian dolls? Also, this is the latest moment in the movie where nobody in that fan forum seems to be aware of the fact anymore that you can't go back any further than to when you've turned on the time machine you're travelling in.
All this weirdness ends with them both at some airport, where the "good" guy tells the "evil" guy (let's call these two the "final versions") to take one of the planes and leave him the heck alone, while at the same time some earlier versions of them are waking up from having been knocked out and free themselves from where they've been locked in. We then see the final version of the "evil" guy set up some building-sized time machine in some (far-away?) Francophone country with the help of many construction workers.