‘2001: A Space Odyssey’ celebrates its big 50th birthday this year. Originally released on April 3, 1968, the cerebral science fiction film, with its stunning special effects, existential scope, psychotic computer, has become the absolute benchmark for visionary futuristic cinema, and nearly half a century later, it has never been surpassed.

Adapted from an Arthur C. Clarke story, Stanley Kubrick’s film is a trippy, epic examination of alien contact, artificial intelligence, the past and future of mankind, and so much more. The scope and nature of its philosophical musings set the movie apart from most other science fiction films. A Space Odyssey inquires about our place in the universe and the nature of humanity.

Although taking place in back in 2001 and the optimistic future that was imagined in 1968, the film appears and feels believable. That is no coincidence, since Kubrick and Clarke in their aim to anchor the film in realism recruited science scholars such as astronomer Carl Sagan, and others from NASA.

Upon release, 2001 polarized critical opinion, receiving both ecstatic praise and vehement derision. Today, it is widely recognized as a masterpiece. Many credit 2001 with opening up a market for films such as Close Encounters of the Third Kind, Alien, Blade Runner, Contact, and Interstellar; proving that big-budget “serious” science-fiction films can be commercially successful, and establishing the “sci-fi blockbuster” as a Hollywood staple.

There are plenty of scenes that stand out in 2001: A Space Odyssey. Not only in the feature, but for film history. One of those is the giant centrifuge. Stanley Kubrick achieved this shot of the astronaut exercising in artificial gravity with Vickers-Armstrongs Engineering Group building him a giant centrifuge that measured 38 feet in diameter and 10 feet wide. This set gave the illusion Kubrick was looking for and is still a marvel of ingenuity. There is another scene that goes down in sci-fi history as one of the most iconic, a scene with a quote that also happens to one of the most famous in movie history.

I’m sorry, Dave.

HAL (Heuristically programmed ALgorithmic computer), or more precisely HAL 9000, is a sentient computer (or artificial general intelligence) that controls the systems of the Discovery One spacecraft and interacts with the ship’s astronaut crew.

HAL’s mission is ambiguous in the film, as the AI is unable to resolve a conflict between his general mission to relay information accurately to the Discovery crew, and orders specific to the mission requiring that he withhold from Bowman and Poole the true purpose of the mission.

A conflict that eventually makes HAL run amok, killing all the astronauts except for their wily commander, Dave Bowman. In an epic showdown between man and machine, Dave, played by Keir Dullea, methodically lobotomizes HAL even as the computer pleads for its life in a terminally decelerating soliloquy.

“I’m sorry, Dave. I’m afraid I can’t do that.”

– HAL

After the film was released fans noticed HAL was a one-letter shift from the name IBM, this has been denied by both by both Arthur C. Clarke and 2001 director Stanley Kubrick. But, IBM was in fact consulted during the making of the film.

HAL’s capabilities, like all the technology in 2001, were based on the speculation of respected scientists. Marvin Minsky, director of the MIT Computer Science and Artificial Intelligence Laboratory (CSAIL) and one of the most influential researchers in the field, was an adviser on the film set.

2001: A Space Odyssey remains relevant not just because it still fills art house theaters, sells DVDs, and is a success in online streaming, but also because references and spoofs of it continue to reverberate throughout the media landscape and HAL very much foreshadowed our anxious contemporary discussion about the potentially dystopian impact of artificial intelligence technologies.

This article is part of the series Iconic Scenes from Science Fiction