Contains spoilers, but definitely not explanations. Also: The reviewer once wrote a term paper on time travel under general relativity. This means he cares a lot about it but not that he knows what he’s talking about.

I’ve been boring my friends for a long time now with my contention that there hasn’t been a really good science fiction movie made about the experience of time travel – something that suggests how it might feel to be a time traveller in the same way that 2001: A Space Odyssey suggested how it might feel to journey through space. Might Primer be that film?

It seems to me that time travel would be an extraordinarily disorienting experience, something that’s largely been ignored in most pop-cultural treatments of the subject. These tend overwhelmingly either to use time travel as a way to add novelty to a caper (Back to the Future), quest (The Terminator) or farce (Groundhog Day). Sometimes it’s a handy “reset button” (see Quantum Leap) and occasionally a way of adding a particularly bittersweet twist to an otherwise linear story – the modern equivalent of a soothsayers’ prophecy fulfilled (Twelve Monkeys).

But what they generally don’t do is address the problems of trying to negotiate an eerily familiar environment using only unreliable memories – in fact, you could argue (and I have) that the best treatments of that subject so far are actually to be found in Memento, or perhaps Eternal Sunshine of the Spotless Mind – both of which actually use amnesia as their central plot device. I haven’t seen a movie which uses time travel to create the same effect – Donnie Darko comes close, but its “time travel” is virtually indistinguishable from magic. So: no good time travel movies.

Until Primer, that is. Shane Carruth’s microbudget ($7,000!) debut feature hits the ground running. It scores points immediately by dumping us into the garage workshop of a bunch of fast-talking, evidently brilliant boffins whose patter is almost entirely convincing; there’s plenty of technobabble here, but it’s plausible technobabble. (Primer’s style has been described as “analog egghead”, which I would dearly love to see become sci-fi’s next wave.) They could be building anything from Google to a cold-fusion plant, but in fact they’re developing a superconducting rig that can partially levitate objects – which turns out, unexpectedly, to also be a time machine.

It’s a plausible time machine, too: it seems to generate closed timelike curves and its physics are reasonable, if necessarily speculative. There’s none of that “meet yourself and you’ll explode!” bollocks here: mass-energy is conserved, time changes direction but not speed; and there’s even a nod to entropy with the notion that repeated or interrupted travel is harmful (leading to lousy handwriting, spontaneous bleeding and worse). Okay, you need to suspend your disbelief when it comes to the machine’s economy and portability, but that’s not too difficult. It’s certainly no harder than it is to believe in a fusion-powered DeLorean …

Of course, this versimilitude would count for little if all Carruth did with it was to show us Eloi and Morlocks, but that’s not the case. During the film’s brief running time, the central characters – the elementally-named Abe and Aaron – take an unspecified number of trips through the box, creating at least nine time-lines along the way. The first few trips are confusing enough – and made slyly more so by the rapid-fire dialogue, anonymous locales and use of flashbacks – but the story rapidly grows much more tangled when it transpires that there are additional boxes and that Aaron, a control freak if ever there was one, has been making covert solo trips to arrange various matters to his liking and impersonating himself at critical junctures.

In fact, the use of the word “tangled” is misleading here: it suggests solving the puzzle is just a matter of patiently following the threads to their ends, whereas that approach would actually only end up with a handful of loose ends. Carruth’s boldest move is to revisit his time travelers’ bewilderment on Primer’s viewers – even when that means abandoning linearity and narrative resolution. Just as those caught up in a temporal paradox may never be able to gather the information needed to make sense of their experiences, so Primer’s viewers aren’t given enough information to fully decipher the movie’s narrative.

The best example is that of Granger, a potential investor who disrupts Abe and Aaron’s plans after discovering one of their boxes and taking an ill-advised trip – or rather, that’s what they (and we) assume, since we never see the chain of events that lead him there. And just as they struggle to deal with his sudden manifestation, so do we. As Carruth says in an interview: “The universe is not going to explode or break down if you create a paradox. Whatever’s going to break is probably going to be you.” The film isn’t going to explode or break down if you introduce an unexplained narrative element …

So Primer is playing an intertextual game with the viewer that reminds me a bit of Blade Runner, with its multiple edits and corresponding interpretations. There’s another layer, too, in the characters of Abe and Aaron: almost instinguishable at the outset, their divergent paths also suggest bifurcating timelines, in this case splitting as a function of free will, rather than causality. But Primer is no Blade Runner: it has only a feeble emotional core. It seems rather begrudging to complain that a film (and director) which gets so much right, working with so little, fails to deliver in the acting department: but there it is.

Whereas Blade Runner’s replicants make us question what it is to be human, Primer’s humans never seem like much more than automatons. Of course, science fiction frequently skimps on character development, but in Primer’s case the problem’s not so much that characterisation is absent as underdone. Aaron’s actions are perplexing because they’re clumsily introduced, not because they fit into Primer’s puzzle-box, and that undermines the force of the consequent developments. So while Primer is a great time-travel movie, it’s not quite a great movie overall. But that’s good enough for me.