Science Fiction, Mystery, Thriller
Kubrick Blinded Me with Science
2001: A Space Odyssey is a science fiction film. In fact, co-author Arthur C. Clarke has said that Kubrick started the entire project because he wanted to make the "proverbial 'really good' science-fiction movie," implying there hadn't been any good ones before then. (Source)
Before 2001, science fiction was viewed less as a genre and more of a hive for breeding B-movies. The genre was replete with aliens traveling the distances of space to have an intergalactic rumble or rubber-suited monsters fighting against a backdrop of cardboard boxes unconvincingly propped up to represent a cityscape. (We're looking at you, Godzilla and Mothra.)
To separate himself from these films, Kubrick created entirely new practical effects that were so convincing that they still look great today but were also as realistic as possible given the scientific knowledge of the day.
"[Kubrick] wanted us to make certain that every detail was legitimate," noted Fred Ordway, scientific consultant on 2001. "So the geophysical instrumentation, the astronomical module, the chemical analysis module, the communications module, the hibernation module, all of these modules on the Discovery spaceship had to be exact" (Source).
Given this attention to detail, 2001 is what some sci-fi connoisseurs would call "hard science fiction." That is, the story's vision of the future attempts to stick as closely as possible to the rules set by science. A perfect example of this in 2001 is that there's no sound in the space scenes. This is because space is a vacuum, so what we perceive as audible sound—waves that vibrate air molecules—have nothing to pass through. Compare this to the softer science fiction of Star Wars, where you can hear every boom and thrust of the engines and the science is basically techno-magic.
Kubrick made some compromises, though. For example, the ship shouldn't appear to move relative to the stars, but the stars were allowed to drift across the screen to prevent scenes from looking too static. Also, half of the Discovery One should be invisible, because it isn't receiving the sun's light, but this would obviously be distracting, so the whole ship gets its time to shine. (Source)
Also, given our scientific knowledge today, some of the details are no longer accurate. For example, you might notice that the Earth is a very, very pale blue in the film. Since Kubrick didn't have the satellite photographs we take for granted today, he had to take his best guess as to what Earth would look like from space.
This scientific detail influences the story Kubrick and Clarke were trying to tell. For example, computer scientists can't determine how to program artificial intelligence or whether it's even possible. So HAL's consciousness remains an open question throughout the film, whereas other science fiction films might take A.I. as simply a given.
Another example is that the extraterrestrials aren't provided any screen time, despite extensive lobbying by the intergalactic members of SAG. This decision was made because science has no idea what aliens that evolved on another planet might look like. As a result, Kubrick did away with the humanoid alien—those aliens that look just like humans except for skin color, facial features, and scales in places where they really shouldn't be. Not seeing the ETs in 2001 adds to the mystery and sense of transcendence that Kubrick was trying to convey. All we see is the monolith, which reveals nothing.
Who Are You? Who? Who?
2001 is also a mystery, and that mystery revolves around the black monolith. What extraterrestrial entities placed this trail of cubic breadcrumbs for humanity to follow? Why did they intervene in our evolutionary process? How did they do it? What do they gain from it? How do the monoliths work? Seriously, would it have killed them to have left a note or something? The film asks its audience to be detectives and draw their own conclusions.
You Know It's Thriller, Thriller Night
2001 also has a teaspoon of thriller flavor, especially in the film's third section. Even before HAL's mistake about the antenna, Bowman's efforts to retrieve the AE-35 unit are thrilling. The slow, methodical pace of the spacewalk and the constant reminder of danger as represented by his audible breathing are nerve-wracking. The total silence makes the scene even more anxiety-inducing. In Jaws, we at least got some warning from the tuba that the shark was about to attack.
When the crew members decide they might have to disconnect HAL, and HAL learns of their plans, the movie goes into full thriller mode. The only thing missing is a voiceover by Vincent Price. As a serial killer, HAL puts Norman Bates to shame. He manipulates the EVA pod to knock Poole into space and kills the three hibernating scientists with no more effort than it takes to flip a switch.
If you ever start doubting the horror elements of the film, try this: Grab someone you know who was in college in 1968. Look them in the eye, and in an insistent but preternaturally calm voice say, "I'm sorry, Dave. I'm afraid I can't do that.". Watch the color slowly drain from their face. In Shmoop's exhaustive research, 75% of those baby boomers were hiding under the bed within 30 seconds.
The scene of Bowman's pod hanging in the empty, vast blackness of space, helpless outside the ship, and Bowman slowly realizing that HAL has shut him out…well, it's a moment of quiet terror. We'll be right back—we need to get our blankie.