There is nothing small about Christopher Nolan's newest, longest film, the epic space drama Interstellar. Its strengths are as gargantuan and overpowering as its mighty flaws, and just as impossible to miss. I have absolutely no idea whether I liked it as a work of cinema, but I know this much for a dead certainty: it is worth seeing, and it is worth seeing on the biggest screen available, even with the known problem in the IMAX sound mix where Hans Zimmer's overly Philip Glassy score smothers the dialogue in a blanket of rampaging strings. Not since Avatar (a film whose dopey script looks like Chayefsky next to the structural disaster written by Nolan and his brother Jonathan) has there been a VFX-driven movie whose value is so clearly a function of letting it wash over you as a sensory event rather than trying to appreciate on the level of narrative.

It's easy to see how that could play as a criticism, but in fact, when a film's sensual elements are as rich and robust and emphatic as they are in the case of Interstellar, it's really not. Nolan has surrounded himself with a crack team of craftspeople, some of them new to his fold, and together they've built one of the most dumbfoundingly physical space movies in a generation: practical effects and sets whenever possible (courtesy of production designer Nathan Crowley), based on real-world observation of actual space programs and technology. When practical effects weren't possible, they were completed in advance of the shoot, so they could be projected behind the actors during the shoot, giving them something to play against that wasn't a green screen. And even here, there was much in the way of motion control model work. The results are not flawlessly realistic (the effects seen through the windows of the main spaceship tend to be a little overexposed, for one), but they are weighty in a way that only the very, very best CGI has ever been - if we weren't just a year away from Gravity, I'd be fairly well inclined to say that no effects-heavy film since The Lord of the Rings closed up shop has had a greater sense of its own physical reality. Paul Franklin, receiving his very own title card for supervising the visual effects, fully earns that odd crediting rarity; the film is his brainchild as much as it is anybody's.

It's a pridefully old-school approach to making a pridefully old-school movie: Interstellar is indebted, rather openly, to the hard science fiction of the mid-20th Century, focusing on science as a problem solving tool and technology as an extension of current thought rather than a magical fantasy element. And human characters are stripped-down and spare, functional objects that exist mostly to do the science and wield the technology. Sometimes. Mostly. It's where the film starts to get itself into trouble a bit.

Here's the deal: Interstellar is, like, five movies, playing out mostly in order. First, there's the "we used up the future, and Earth is dying" opening, in which we meet former fighter pilot Cooper (Matthew McConaughey), his father-in-law Donald (John Lithgow), and his children Tom (Timothée Chalamet), a teenager, and Murphy (Mackenzie Foy), a 10-year-old. But not his wife. She's dead. This is a Nolan picture. Then there's Cooper's discovery that, in secret, the U.S. government has kept the space program alive to work on developing a "get the hell off the Earth" program, under the guidance of wizened Dr. Brand (Michael Caine). Then there's the actual mission, with Cooper, Brand's daughter Amelia (Anne Hathaway), physicist Romily (David Gyasi), and geologist Doyle (Wes Bentley) all trekking through a mysteriously convenient wormhole to explore a trio of potential Earth-2s. And there are between two and three more movies after that, but I can't go farther without hitting spoiler territory.

Anyway, the film occupies a billion different tonal registers, veering from the mercilessly austere hard science of the second and third chunks, all the way the the weepy sentimentality of... also the third chunk, since that's when the effects of relativity cause Murphy to grow up into a resentful adult played by Jessica Chastain, working with Dr. Brand as a way of focusing her rage at her dad into something useful. And there are rare communications between them, and really fucking amazing cross-cutting, courtesy of Lee Smith, Nolan's usual editor. And here the characters feel deep, passionate feelings, and Zimmer's Glass impression shifts gears to be far more weepy and romantic. Sometimes it works - Cooper's discovery of a whole package of video messages charting his family's growth over years while he was being time dilated is one of the best moments in the film, boasting a wordless, heartbreaking performance by McConaughey that's unequivocally the best acting anywhere in the movie. Sometimes it doesn't work, like in the agonising, endless first half hour, when the Nolans laboriously set up their family dynamic in long scenes that have heard of narrative efficiency only as something for puny mortal directors who have budgetary restrictions.

The whole script is a car wreck, heavily over-emphasising some details and skipping madly over others, building a world that is excruciatingly spelled out with details that make no sense - like a scene that plays out for minutes and minutes, establishing that the government has declared the moon landing of the ancient past to be a hoax, although what conceivable reason they'd have for doing this is unclear, and what reason Interstellar has for making us watch characters who theoretically know this already to carefully, leadenly hash it out is even less clear (for that matter, given the world the movie depicts - the economy has collapsed, agriculture is collapsing, and people have apparently retrenched into semi-anarchic rural enclaves - why is there still a U.S. government at all?). But then, painfully stretched-out delivery of expository dialogue between two people who both know all the things they're describing happens a lot in Interstellar, and it's never natural, but sometimes it is useful. Even if you walk in a complete neophyte on the worlds of quantum physics and general relativity, you surely will know a lot about them when you walk out. Or, at least, the reductive version the Nolans need to make their plot go.

But even as the story wanders in tiny circles for ages, stopping with gobsmacked amazement for draggy scenes of little value, for every one annoyance, Interstellar offers up two moments of pure visceral movie magic. It is, for the most part, not a film where Nolan's sometimes-notorious difficult in organically stitching two shots together has resolved itself; their are difficulties in figuring out the layout of certain key spaces that pervade the whole movie. But the individual images themselves are so dauntingly huge - and I can't over-stress that this movie begs and craves to be seen in IMAX - and so impressively captured by Nolan and cinematographer Hoyte Van Hoytema (stepping in for absent Nolan regular Wally Pfister), and Franklin, that the relationship between shots is simply never as important as the impact shots make themselves. There are moments of genius - generally, cross-cutting between Cooper on the spaceship and Murphy on Earth is done with a fluidity and sensibility that creates more human meaning than the script ever does, though the final action scene, cross-cutting madly, is kind of ridiculously over-the-top.

But that's the thing: Interstellar moves from brilliance to absolute ineptitude and back regularly and freely. Just about the only thing that's not true of is the acting: with the script bathed in the traditions of hard sci-fi, hardly any of the characters have room for more than the impression of inner life, which means that such gifted people as McConaughey, Chastain, Hathaway, Lithgow, and others whose parts are so small I didn't even get to them are largely there to add gravitas to undernourished roles, but not to do very much real capital-A acting. It's easy for Interstellar to forget its human elements; they are not what it finds interesting, and when it focuses on them, it's usually embarrassingly ripe. But at least the top-shelf cast inhabits their thin stock types with presence and solidity that give the film just enough of an anchor that when it tries to be an emotionally resonant character drama, it kind of feels like it might work, even if it never quite makes it. Anyway, it's not as befuddlingly confused about what makes for plausible human behavior as The Dark Knight Rises, so, I don't know, progress?