If Christopher Nolan’s movies are anything they are grounded.

His breakthrough Memento is a time travel movie with no actual time travel. His Batman trilogy stripped away Tim Burton’s gothic operatics to create bleeding, bruised Caped Crusader confronting a terrorist siege.

And The Prestige – which I call “Batman vs. Wolverine, With Magic” – doesn’t contain magic or mysticism, just stagecraft, misdirection and technology.

Nolan’s literalism has led some critics to ding his movies for lacking “poetry,” and rightly so. Still, the Batman trilogy remains intriguing and unique, in part, because Nolan seemingly had to understand the superhero in literal terms to make a movie about him.

Nolan’s literalism also gives him a tendency toward flat-footed and overly expository dialogue. His movies always come with a clearly voiced thesis statements, such as The Dark Knight’s “You either die a hero or you live long enough to become the villain” or the wonderfully memeable “Some men just want to watch the world burn”

Matthew McConaughey growls “We used to look up at the sky and wonder at our place in the stars. Now we just look down and worry about our place in the dirt.” That seems a usable enough premise for a great sci-fi movie.

Interstellar certainly seemed promising, if not downright thrilling in its potential. Film’s grounded literalist was basically getting all the money and making a space movie. After Nolan’s successes, he could clearly do what he wanted.

Top theoretical physicists were consulted to make sure the special effects were scientifically accurate, not just pretty. And they are both. The black hole Gargantua makes for a looming, silent cinematic presence while being so accurate that a scientific paper was written about discoveries made during its creation.

Everything suggested the movie would be a literal look at man’s expansion into space. Who couldn’t watch the teaser with its highlight reel of spaceflight achievements and not get excited. Or, less promisingly, be reminded of the Star Trek: Enterprise opening credits.

Turns out, however, Interstellar ended up with a competing thesis statement, found in Anne Hathaway’s “love is the most powerful force in nature” soliloquy.

Physics, meet metaphysics. Again.

Science fiction dominates movies, but hard sci-fi is a rare treat. We get, what, one or two per decade? Yet the mark of “serious” sci-fi is to wander off into religious allegory, with some scene of the protagonist floating around in a glowey white space heaven as orchestral music swells.

You find that theme in most serious, ambitious sci-fi movies. 2001: A Space Odyssey works quite well as Christian allegory. Mankind is awakened to his potential by an unseen higher power who eventually helps Dave Bowman throw off physical constraints and concerns as a transcendent being.

Contact – whose bravura opening shot weds science and cinematic wonder for one of the most beautiful sequences in all of sci-fi – uses science to transport Ellie Arroway across the galaxy. But only faith allows her to accept alien visitation in the form of her beloved father in a tropical alien afterlife.

In Gravity, broadcasting “in the clear” is a form of prayer that give Ryan Stone strength to achieve physical survival and spiritual renewal.

When Star Trek went the big-ideas route in the ill-fated Star Trek: The Motion Picture the producers hired 2001’s Douglas Trumbull for the special effects and sent the crew off on a search for God and meaning. The crew met God again in Star Trek V but it turned out less well for God as he failed to meet Shatner’s standards and was killed.

Interstellar has its own big-ideas religious themes to unpack. The more obvious is the Christ analogy of McConaughey’s Cooper leaving earth with a promise to return and save humanity from destruction. A black hole serves as a celestial Pearly Gates that instead of horribly killing Cooper, it sends him into the Space Library of Congress to create the movie’s bootstrap paradox.

Or maybe higher beings save him. Or super-advanced humans. It’s confusing that way.

Including all this religiosity doesn’t necessarily make for a bad sci-fi story.

These movies are just the stories we like to create and to tell and the ideas we grapple with. Most people know that Joseph Campbell formulated the idea of cross-cultural themes after George Lucas popularized the idea with Star Wars.

Lucas was savvy enough to throw in some quasi-religon sorcerer’s ways into “Star Wars” to keep things mythic.

But religious allegory has become the go-to sci-fi story. Coldly atheistic Alien was transubstantiated into a quest to find our creator in the muddled Prometheus, presumedly so the story could be “more meaningful.”

Humans are tiny and fragile compared with the scale and brutality of the universe, a theme Interstellar handles well. The human reaction to our smallness is to conjure up gods with the power to control what’s beyond our grasp.

Creating distant benevolent entity playing to our better natures and saving humanity with technology indistinguishable from magic is just inventing God out of science and reason.

Like so many in sci-fi, Nolan seemed unwilling to send his characters out into a godless and barren universe filled with discovery, fact and reason, toward the kind of movie he seemed so suited to make.