A.I. Artificial Intelligence (2001)

These days, the letters “AI” bring to mind social media squabbles, in which tech bros announce that a computer has created a perfect piece of art and people with functional eyes contend that it decidedly has not. But for much of the 20th century, the concept of artificial intelligence captured the imagination of artists most concerned with exploring the definition of humanity. That included filmmaker Kubrick, who died before he could adapt the story “Supertoys Last All Summer Long” by Brian Aldiss, leaving his friend Steven Spielberg to take over. The result is a sometimes uneven story about a robotic boy called David (Haley Joel Osment) looking for acceptance.

As you might expect, viewers are quick to attribute the colder parts of Kubrick and the warmer parts to Spielberg. However, according to most accounts, Spielberg was responsible for the movie’s chilling ending, in which David gets trapped in an abandoned Coney Island attraction with a blue statue in front of him. Believing the statue to be the fairy from Pinocchio, David begs the statue to make him into a real boy, repeating his plea until his power runs out and he dies. Then, 2000 years later, aliens arrive, retrieve David, and genetically engineer a clone of his human mother Monica (Frances O’Connor), who reads a story to him. It’s such a shocking close to the movie that viewers continue to argue about whether or not it’s real or a hallucination and, more importantly, whether it is a happy or devastating ending. 

Stalker (1979)

In the final act of Stalker, the three main characters finally reach their goal: the mysterious Room at the center of the irradiated Zone, rumored to grant the deepest wish of anyone who answers. Like the hedonistic Writer (Anatoly Solonitsyn), the Professor (Nikolai Grinko) hired the Stalker (Alexander Kaidanovsky) to lead through the Zone to the Room — he for answers to life’s deepest secrets, the Writer for inspiration. But as they near, the Professor reveals that he has a bomb and plans to destroy the Room, in hopes of keeping it out of an evil person’s hands. 

Sounds pretty exciting, huh? Well, it is, but maybe not in the way that you’d expect. Instead of a giant battle, Russian director Andrei Tarkovsky’s adaptation of the novel Roadside Picnic by Arkady and Boris Strugatsky (who also wrote the screenplay) ends in conversation. Unlike some of the other sci-fi movies on this list, Stalker does not try to hide the talking within cool action sequences. Instead, it leans hard into a philosophical debate about the nature of humanity and morality. As a result, the movie may come to a fairly simple narrative conclusion (they do not destroy the Room), but the point cannot be explained, especially with the final scene of the Stalker’s daughter (Natasha Abramova) apparently using telekinesis while reciting a poem.

Primer (2004)

Look, we all know that time travel movies are confusing. And most of us accept that. We don’t need to know how Ted managed to travel back to the moment his past self mentioned to drop a garbage can on his father’s head so he and Bill can escape. We just know that Wyld Stallyns rule. But that wasn’t good enough for Shane Carruth, who decided to make a realistic time travel movie with Primer. Instead of giving us futuristic phone boxes or Deloreans with flux capacitors, Primer features “the box,” a time-travel device accidentally created in a garage by engineers Abe (David Sullivan) and Aaron (Carruth). And instead of seducing their mothers or finishing their homework, the duo does what most of us would do with a time machine and uses it to play the stock market. 

But in pursuit of realism, Primer somehow becomes far more confusing than nearly every other time-travel movie. And that’s because of the movie’s most realistic aspect, the jealousy that drives apart Abe and Aaron and interference from others who want money themselves. As Abe and Aaron use the machine to outwit one another and then try to reconcile with each other, they create more and more versions of themselves existing in overlapping timelines, so dense that not even a flowchart on Wikipedia can make sense of it. By the time the movie closes, we know that Abe from the future is working to protect Abe from the past (more accurately, the business gains his work affords). But the kaleidoscopic nature of the story means that there are probably even more Abes and Aarons, staring from just outside the frame.