Audiences who came to “2001” expecting a sci-fi movie got, instead, an essay on time. The plot was simple and stark. A black monolith, shaped like a domino, appears at the moment in prehistory when human ancestors discover how to use tools, and is later found, in the year 2001, just below the lunar surface, where it reflects signals toward Jupiter’s moons. At the film’s conclusion, it looms again, when the ship’s sole survivor, Dave Bowman, witnesses the eclipse of human intelligence by a vague new order of being. “2001” is therefore only partly set in 2001: as exacting as Kubrick was about imagining that moment, he swept it away in a larger survey of time, wedging his astronauts between the apelike anthropoids that populate the first section of the film, “The Dawn of Man,” and the fetal Star Child betokening the new race at its close. A mixture of plausibility and poetry, “real” science and primal symbolism, was therefore required. For “The Dawn of Man,” shot last, a team travelled to Namibia to gather stills of the desert. Back in England, a massive camera system was built to project these shots onto screens, transforming the set into an African landscape. Actors, dancers, and mimes were hired to wear meticulously constructed ape suits, wild animals were housed at the Southampton Zoo, and a dead horse was painted to look like a zebra.

For the final section of the film, “Jupiter and Beyond the Infinite,” Ordway, the film’s scientific consultant, read up on a doctoral thesis on psychedelics advised by Timothy Leary. Theology students had taken psilocybin, then attended a service at Boston University’s Marsh Chapel to see if they’d be hit with religious revelations. They dutifully reported their findings: most of the participants had indeed touched God. Such wide-ranging research was characteristic of Clarke and Kubrick’s approach, although the two men, both self-professed squares, might have saved time had they been willing to try hallucinogens themselves.

The Jupiter scenes—filled with what Michael Benson describes as “abstract, nonrepresentational, space-time astonishments”—were the product of years of trial and error spent adapting existing equipment and technologies, such as the “slit-scan” photography that finally made the famous Star Gate sequence possible. Typically used for panoramic shots of cityscapes, the technique, in the hands of Kubrick’s special-effects team, was modified to produce a psychedelic rush of color and light. Riding in Dave’s pod is like travelling through a birth canal in which someone has thrown a rave. Like the films of the late nineteenth century, “2001” manifested its invented worlds by first inventing the methods needed to construct them.

Yet some of the most striking effects in the film are its simplest. In a movie about extraterrestrial life, Kubrick faced a crucial predicament: what would the aliens look like? Cold War-era sci-fi offered a dispiriting menu of extraterrestrial avatars: supersonic birds, scaly monsters, gelatinous blobs. In their earliest meetings in New York, Clarke and Kubrick, along with Christiane, sketched drafts and consulted the Surrealist paintings of Max Ernst. For a time, Christiane was modelling clay aliens in her studio. These gargoyle-like creatures were rejected, and “ended up dotted around the garden,” according to Kubrick’s daughter Katharina. Alberto Giacometti’s sculptures of thinned and elongated humans, resembling shadows at sundown, were briefly an inspiration. In the end, Kubrick decided that “you cannot imagine the unimaginable” and, after trying more ornate designs, settled on the monolith. Its eerily neutral and silent appearance at the crossroads of human evolution evokes the same wonder for members of the audience as it does for characters in the film. Kubrick realized that, if he was going to make a film about human fear and awe, the viewer had to feel those emotions as well.

And then there is HAL, the rogue computer whose affectless red eye reflects back what it sees while, behind it, his mind whirrs with dark and secret designs. I.B.M. consulted on the plans for HAL, but the idea to use the company’s logo fell through after Kubrick described him in a letter as “a psychotic computer.” Any discussion of Kubrick’s scientific prescience has to include HAL, whose suave, slightly effeminate voice suggests a bruised heart beating under his circuitry. In the past fifty years, our talking machines have continued to evolve, but none of them have become as authentically malicious as HAL. My grandfather’s early-eighties Chrysler, borrowing the voice from Speak Spell, would intone, “A door is ajar,” whenever you got in. It sounded like a logical fallacy, but it seemed pleasantly futuristic nonetheless. Soon voice-command technology reached the public, ushering in our current era of unreliable computer interlocutors given to unforced errors: half-comical, half-pitiful simpletons, whose fate in life is to be taunted by eleven-year-olds. Despite the reports of cackling Amazon Alexas, there has, so far, been fairly little to worry about where our talking devices are concerned. The unbearable pathos of HAL’s disconnection scene, one of the most mournful death scenes ever filmed, suggests that when we do end up with humanlike computers, we’re going to have some wild ethical dilemmas on our hands. HAL is a child, around nine years old, as he tells Dave at the moment he senses he’s finished. He’s precocious, indulged, needy, and vulnerable; more human than his human overseers, with their stilted, near robotic delivery. The dying HAL, singing “Daisy,” the tune his teacher taught him, is a sentimental trope out of Victorian fiction, more Little Nell than little green man.

As Benson’s book suggests, in a way the release of “2001” was its least important milestone. Clarke and Kubrick had been wrestling for years with questions of what the film was, and meant. These enigmas were merely handed off from creators to viewers. The critic Alexander Walker called “2001” “the first mainstream film that required an act of continuous inference” from its audiences. On set, the legions of specialists and consultants working on the minutiae took orders from Kubrick, whose conception of the whole remained in constant flux. The film’s narrative trajectory pointed inexorably toward a big ending, even a revelation, but Kubrick kept changing his mind about what that ending would be—and nobody who saw the film knew quite what to make of the one he finally chose. The film took for granted a broad cultural tolerance, if not an appetite, for enigma, as well as the time and inclination for parsing interpretive mysteries. If the first wave of audiences was baffled, it might have been because “2001” had not yet created the taste it required to be appreciated. Like “Ulysses,” or “The Waste Land,” or countless other difficult, ambiguous modernist landmarks, “2001” forged its own context. You didn’t solve it by watching it a second time, but you did settle into its mysteries.

Later audiences had another advantage. “2001” established the phenomenon of the Kubrick film: much rumored, long delayed, always a little disappointing. Casts and crews were held hostage as they withstood Kubrick’s infinite futzing, and audiences were held in eager suspense by P.R. campaigns that often oversold the films’ commercial appeal. Downstream would be midnight showings, monographs, dorm rooms, and weed, but first there was the letdown. The reason given for the films’ failures suggested the terms of their redemption: Kubrick was incapable of not making Kubrick films.

“2001” established the aesthetic and thematic palette that he used in all his subsequent films. The spaciousness of its too perfectly constructed sets, the subjugation of story and theme to abstract compositional balance, the precision choreography, even—especially—in scenes of violence and chaos, the entire repertoire of colors, angles, fonts, and textures: these were constants in films as wildly different as “Barry Lyndon” (1975) and “The Shining” (1980), “Full Metal Jacket” (1987) and “Eyes Wide Shut” (1999). So was the languorous editing of “2001,” which, when paired with abrupt temporal leaps, made eons seem short and moments seem endless, and its brilliant deployment of music to organize, and often ironize, action and character. These elements were present in some form in Kubrick’s earlier films, particularly “Dr. Strangelove,” but it was all perfected in “2001.” Because he occupied genres one at a time, each radically different from the last, you could control for what was consistently Kubrickian about everything he did. The films are designed to advance his distinct filmic vocabulary in new contexts and environments: a shuttered resort hotel, a spacious Manhattan apartment, Vietnam. Inside these disparate but meticulously constructed worlds, Kubrick’s slightly malicious intelligence determined the outcomes of every apparently free choice his protagonists made.

Though Kubrick binged on pulp sci-fi as a child, and later listened to radio broadcasts about the paranormal, “2001” has little in common with the rinky-dink conventions of movie science fiction. Its dazzling showmanship harkened back to older cinematic experiences. Film scholars sometimes discuss the earliest silent films as examples of “the cinema of attraction,” movies meant to showcase the medium itself. These films were, in essence, exhibits: simple scenes from ordinary life—a train arriving, a dog cavorting. Their only import was that they had been captured by a camera that could, magically, record movement in time. This “moving photography” was what prompted Maxim Gorky, who saw the Lumière brothers’ films at a Russian fair in 1896, to bemoan the “kingdom of shadows”—a mass of people, animals, and vehicles—rushing “straight at you,” approaching the edge of the screen, then vanishing “somewhere beyond it.”

“2001” is at its best when it evokes the “somewhere beyond.” For me, the most astounding moment of the film is a coded tribute to filmmaking itself. In “The Dawn of Man,” when a fierce leopard suddenly faces us, its eyes reflect the light from the projection system that Kubrick’s team had invented to create the illusion of a vast primordial desert. Kubrick loved the effect, and left it in. These details linger in the mind partly because they remind us that a brilliant artist, intent on mastering science and conjuring science fiction, nevertheless knew when to leave his poetry alone.

The interpretive communities convened by “2001” may persist in pockets of the culture, but I doubt whether many young people will again contend with its debts to Jung, John Cage, and Joseph Campbell. In the era of the meme, we’re more likely to find the afterlife of “2001” in fragments and glimpses than in theories and explications. The film hangs on as a staple of YouTube video essays and mashups; it remains high on lists of both the greatest films ever made and the most boring. On Giphy, you can find many iconic images from “2001” looping endlessly in seconds-long increments—a jarring compression that couldn’t be more at odds with the languid eternity Kubrick sought to capture. The very fact that you can view “2001,” along with almost every film ever shot, on a palm-size device is a future that Kubrick and Clarke may have predicted, but surely wouldn’t have wanted for their own larger-than-life movie. The film abounds in little screens, tablets, and picturephones; in 2011, Samsung fought an injunction from Apple over alleged patent violations by citing the technology in “2001” as a predecessor for its designs. Moon landings and astronaut celebrities now feel like a thing of the past. Space lost out. Those screens were the future. ♦