directed by Christopher Nolan

and starring Matthew McConaughey, Anne Hathaway, Jessica Chastain and Michael Caine

What fills Christopher Nolan’s mind when he looks up at the stars? We know Kubrick ponders the nature of existence; Ridley Scott has nightmares of spacecraft turned to death traps; Michael Bay dreams of robots.

As for the reigning king of the summer blockbuster, he appears transfixed by the power of love…and wormholes. The latter are among “Interstellar”’s highlights, perfect vessels for Nolan to flaunt his prodigious eye for large-scale visual splendor. Like Space Mountain filtered through “2001: A Space Odyssey,” they tickle the gut and brain in equal measure, a thrill ride imbued with metaphysical weight. That dichotomy—between the sensational and the profound—informs much of the film. Problem is, there’s not enough of the latter, and Nolan struggles mightily with the former.

See, Nolan’s not a people person. He conceives of families as plot devices, catalysts for the relentless chug of his breakneck thrillers. When it comes time to pause and reckon with relationships strained and broken, he falters. Nolan’s best films (“The Dark Knight,” “Inception,” “Memento”) derive their power from an unyielding momentum. He needs timers, deadlines, tension. Here, he takes a different tack, letting his characters theorize and formulate as the weight of mankind rests on their shoulders.

What, exactly, mankind needs to be rescued from is a bit murky. We know there’s dust—and lots of it—that hints at an impending environmental crisis. But it doesn’t matter, really. Single father-of-two Cooper (Matthew McConaughey) and his crew of space cadets need to find somewhere else for people to live, and fast.

Sounds simple enough. Establish Earth’s dire state, send a motley crew of attractive science people hurtling into the beyond for giant set pieces and philosophical reflection, mission accomplished. But things aren’t that easy in the Nolan brothers’ (the film was co-written by Christopher’s brother Jonathan) unfocused, often incoherent script. Overwhelmed by the possibilities of deep-space exploration, the Nolans cast their net far too wide, losing the urgency and focus necessary for a film of this size.

Not that the pieces aren’t there. The film’s emotional hook—that Cooper must leave his children parentless indefinitely (and possibly permanently) for the sake of the human race—carries a built-in weight the Nolans can’t sell. They try, at times, but Christopher Nolan’s cool touch with interpersonal relations dulls the impact of the film’s pivotal beats.

In fact, whenever people are talking, “Interstellar” drags. And there’s a lot of talking, particularly in the film’s leaden, exposition-heavy first act, in which tired themes mingle with cliche-ridden dialogue (“This world was never enough for you, Coop,” John Lithgow says with a straight face at one point).

But things will get better when the film goes to space, you think. There’ll be black holes and wormholes and all the CGI-generated planets $165 million can buy. And that’s true, to an extent. The visual bells and whistles do arrive in the film’s final two-thirds, but there’s not nearly enough of them. Given an intergalactic playground, Nolan instead traps McConaughey and Co. in a vessel (ironically titled “Endurance”) marred by unimaginative set design, where they talk, talk and talk some more.

Passing overtures are made to the tragedy of watching your children grow up via video transmission, but what the Nolans neglect is the punishing, wearying loneliness of a decades-long absence from your home planet. There should be frayed nerves and broken spirits. What we get instead are external pressures that attempt to fill the hole where the film’s heart should be.

It’s not like “Interstellar”’s all-star cast (featuring McConaughey, Anne Hathaway, Jessica Chastain, Casey Affleck, John Lithgow, Michael Caine and Ellen Burstyn, among others) couldn’t handle some added responsibility. They deserve room to shine, considering the dreck they so generously wade through. Radiating that rare blend of honesty and movie-star charisma that commands seven-figure paychecks, Nolan’s principals make the best of an unfortunate situation, prying humanity from underwritten characters. Hathaway in particular could have benefitted from some psychological depth, as her quiet, instinctive performance proves a perfect foil to McConaughey’s swagger.

At the least, one would expect Nolan’s visual palette to sparkle when given free reign over the cosmos. He can conjure the wonders of widescreen cinema like few of his peers, but he needs the room to realize his vision. Cramped into “Endurance”’s narrow confines, his camera is stripped of its awe-inspiring power.

But even when Nolan ventures beyond his airlocked quarters, a frustrating tendency to fuse his camera to the side of the ship limits his scope. Not that it matters all that much when every planet looks like Earth, except with lots of water, snow or rocks. As is the case with the film’s interiors, maddeningly literal production design impedes “Interstellar”’s ability to inspire.

The film reaches new lows as it approaches an interminable conclusion. Unable to solve the third act through cinematic means, the Nolans escape via theoretical physics. It’s yet another in a film full of wasted opportunities.

Seeking to craft spine-tingling visions of the beyond, Nolan instead emits a muddled, indecisive love letter to the science-fiction epics of his youth. Sometimes infinity is too much for even the bravest of souls. Count Nolan among their broken ranks.