It’s billed as a biopic of theoretical physicist J Robert Oppenheimer, dubbed the “father of the atomic bomb”. But “biopic” seems too small a word to contain the ambition and scope of Christopher Nolan’s formidable if occasionally unwieldy latest. Oppenheimer is a dense and intricate period piece, playing out in a tangle of timelines. It weaves together courtroom drama, romantic liaisons, laboratory epiphanies and lecture hall personality cults. But perhaps more than all of this, Oppenheimer is the ultimate monster movie. Cillian Murphy’s Oppenheimer is an atomic-age Frankenstein, a man captivated by the boundless possibilities of science, realising too late that his creation has a limitless capacity for destruction. Ultimately, however, the monster in this story is not Oppenheimer’s invention but the appetite for annihilation that it unleashes in mankind. It’s a realisation that plays out, inexorably, in Oppenheimer’s hollow, haunted face as the film unfolds. Murphy’s far-seeing ice-chip eyes have never been put to better use. In fact, Murphy’s physicality as a whole is one of the most potent weapons at the film’s disposal. He seems impossibly slight, a theoretical idea of a man in contrast to the robust certainties of the military figures he works alongside (Matt Damon’s Lt Gen Leslie Groves, for example, is bullish and solid, a clenched fist looking for something to punch). In one shot we see Oppenheimer hauling an armful of books into a new classroom, and it looks as though he’s buckling under the weight of his accumulated knowledge. At other times he’s calm and glassily composed, somehow removed from jostling egos and the fusion of ideas that will take shape into the ultimate weapon. The version of Oppenheimer that we see on screen at any given time is a marker, an indication of which timeline we are currently inhabiting. Insights into his stellar early academic career are punctuated by glimpses of a later humiliating security clearance hearing that picked over every aspect of his life; the development of the bomb – the so-called Manhattan Project – is cut together with another hearing, this time in the Senate, to establish whether Oppenheimer’s former colleague Lewis Strauss (Robert Downey Jr, excellent) should be appointed in a federal government role. It’s a knotty mesh of a structure. Time in Oppenheimer doesn’t feel entirely linear – there are moments, in particular a pivotal encounter with Albert Einstein, that seem unmoored from the rest of the film. Nolan’s films frequently require a couple of viewings to unravel fully, and while it lacks the baffle-factor of Tenet, Oppenheimer is no exception. There are other problems: the cursory treatment of the female characters is one. Florence Pugh, as Oppenheimer’s mistress Jean Tatlock, gets short shrift. And Emily Blunt, as J Robert’s wife Kitty Oppenheimer, spends much of the first two hours mutinously clutching a martini on the edge of the frame. She does, however, claim a couple of terrific moments later on: a skin-flaying interrogation scene; a wordless glare that conveys the full nuclear winter of her animosity towards a disloyal colleague. But, for the most part, the film is a towering achievement. Not surprisingly, given Nolan’s preference for shooting on Imax 70mm film, the picture has a depth of detail you could drown in. There’s no shortage of scenes of furious blackboard scribbling, the accepted cinematic signifier of scientific genius. But more interesting are the abstract moments; it’s as though we are venturing into the heart of the atom itself. Equally inventive is the way the sets seem to quake at moments of tension. Oppenheimer’s world is literally rocked by the shockwaves of the reaction that has been set in motion. Most effective, however, is the use of sound and music. Like Jonathan Glazer’s upcoming The Zone of Interest, this is a film in which the horrors of war are not shown but conveyed inescapably through what we hear. Ludwig Göransson’s score is masterful and mercurial, surely one of the finest of the year. And there’s a recurring motif in the soundscape, a crescendo of thunderously stamping feet. It’s taken from a moment of triumph and glory, the high point of Oppenheimer’s career. But it takes on a mounting sense of threat with each use, as the catastrophic potential of the physicist’s work becomes clear.