ATLAS is one of the detectors at the Large Hadron Collider, a miles-long particle accelerator used to search for the Higgs boson in “Particle Fever.” (Abramorama/BOND360)

In science, a theory is never “true.” It is either disproved . . . or simply not disproved yet.

That lack of certainty colors all scientific advancement, even the 2012 announcement that, after spending decades of work and millions of dollars looking for it, physicists had finally found some evidence that strongly suggested the existence of the elusive Higgs boson, a subatomic chunk of matter sometimes referred to as the “god particle.”

From the excitement on the faces of those in attendance at the historic announcement at CERN, as the Swiss-based European Organization for Nuclear Research is known, you’d never know that the discovery was anything less than rock solid. As documented in the wonky but surprisingly compelling film “Particle Fever," even the most cautious scientists occasionally have reason to get a little worked up.

The ostensible subject of the film is the Large Hadron Collider, or LHC, a massive, miles-long particle accelerator designed to detect the Higgs boson by replicating, in miniature, the Big Bang. It works by smashing together two high-energy proton beams aimed directly at each other. Comprised of liquid-helium-cooled magnets and complex microelectronics that one scientist compares to a “five-story Swiss watch,” the LHC is the world’s largest crash-test laboratory.

Since 1964, when Peter Higgs first postulated its existence, the Higgs boson has been a missing piece in the puzzle of modern physics, which attempts to explain the universe as a carefully balanced network of particles and forces.

But the real stars of the film are the half-dozen physicists who tell the story of the search for the Higgs boson, lending the tech talk real drama. They’re led by David Kaplan, a theoretical physicist at Johns Hopkins University who acts as a kind of tour guide to the story and helps simplify a complex subject for a general audience, many of whom would never otherwise care about any of this.

Kaplan, who once considered filmmaking before turning to science, commissioned Mark Levinson, a Hollywood sound man who worked on “The English Patient” and other major films, to direct “Particle Fever.” It plays out with all the suspense of a thriller. Assisted by acclaimed editor Walter Murch, Levinson wisely shapes the story not around the hardware, which was plagued by malfunctions and other delays, but around the people tasked with making the LHC run.

Three of the film’s six protagonists are theorists, armed with chalkboards, and three are experimentalists in hard hats. Two are women, giving the lie to the enduring cliche about the absence of female scientists. But they are all engaging. Along with animations that help illustrate complex concepts, these six “characters” keep the action relatable and entertaining.

That’s no mean feat, given that determining the existence of the Higgs boson bears no clear, practical benefit, economic or otherwise. “Particle Fever” isn’t about the search for a cancer cure, or the race to put a man on the moon or the hunt for some new technology that will enable smarter smartphones. It’s simply about looking for something — something invisible, inconceivably small and possibly apocryphal — that may hold the key to the universe’s last mysteries.

The pursuit of knowledge for knowledge’s sake is science at its purest. As Kaplan says, everyone looking for the Higgs particle always understood that the search could yield nothing, “other than understanding everything.”

★ ★ ★

Unrated. At Landmark’s E Street Cinema. Contains brief obscenity. 99 minutes.