It is hard not to admire Shane Carruth’s sci-fi puzzler “Primer,” a film that operates like a cold mathematical equation, every detail precisely placed. The problem is, as the variables become more and more complex, most viewers will abandon the equation rather than spend the infinite hours required to figure it out.

The solution, if there is one, demands a specialized knowledge of physics few have. A simple glance at the film’s internet message board reveals discussions of Feynman diagrams, wave functions and recursion postulates that would baffle the average filmgoer. “Primer” captures the dual essence of scientific exploration: the exciting quest for knowledge and the boring, impenetrable analysis.

Taking the form of a serious drama about time travel, the film uses the endless possibilities of science as a starting point to explore deeper issues of self and morality. Engineers Abe (David Sullivan) and Aaron (Carruth) are best friends who spend their spare time tinkering with inventions in Aaron’s garage. Using parts from microwaves, fridges and other appliances, they manage to piece together a marketable device that reduces the so-called apparent mass of an object.

A side effect of the machine turns out to be far more important than its original purpose: anything placed within its field travels back in time.

After making this startling discovery, Aaron and Abe begin to cautiously explore the possibilities of their invention, picking stocks and winning the lottery. But once time has been disrupted, things inevitably begin to spin out of control.

Eventually the entire fabric of Abe and Aaron’s existence is called into question: the friends have traveled back so many times that there are, maddeningly, double and triple temporal versions of themselves running around. As the plot implodes in on itself it becomes clear that Carruth’s film is too smart for its own good. He seems more interested in the film’s concepts than in its characters, focusing on the particulars of the machine at the cost of its emotional effects on Abe and Aaron.

So generic that they can be replicated, they are checkers, pieces in the game; arguments, not people. Though this lack of warmth is forgivable while the story makes sense, as it becomes increasingly obtuse there is no hook to retain interest.

Nevertheless, “Primer” remains suspenseful because the script (also Carruth’s) gives the impression that answers are just around the bend. Frustratingly, they never come.

For most of the film, Carruth succeeds in traveling a little faster than the speed of sense, injecting philosophical twists into the mix to keep things interesting. “Primer” is at its best when toying with time, especially when its characters are involved in extrapolating the abstractions. Listening to Abe and Aaron try to figure out what their future selves changed in the past is certainly surreal, but wonderfully so.

Besides starring in the movie, Carruth produced, directed, scored, edited, wrote and directed “Primer” — which was made for an infinitesimal $7,000. Even more impressively, Carruth is a first-time filmmaker.

Visually the movie is expert. No special effects were needed to create the duplicate figures, only smart directing. Thankfully absent are both high-tech special effects and the flourished, bawdy camera movements of the film student. Carruth shoots without adornment, in service of the story.

Although it could easily be construed as a morality tale about the evils of science, “Primer” shies away from making any clear judgements. The film is supposed to be watched and analyzed afterward, not felt; and, as a result, it is difficult to feel emotionally engaged.

A controlled presentation on the loss of control always feels artificial, and Carruth — himself an engineer — seems happy to settle with a laboratory experiment of a film. One wonders what would happen if the restraints were removed.

“Primer” is one of five films showing at the new Criterion Cinemas, a welcome addition to New Haven.