Outer space: Dark. Expansive. Full of lasers and explosions.
The tagline for the 1979 science-fiction horror film Alien was "In space no one can hear you scream", an ironic statement coming from Hollywood. If all the knowledge you had about space was obtained from Hollywood movies you might think the statement is nonsense, as you can almost always hear all sorts of sounds in space. This is obviously incorrect as far as physics goes, however, Hollywood is not interested in vacuum physics as we can plainly see not just in sound design but also in the sheer number of explosions and fire that occur.
It's obvious why they do this, a completely silent space battle is hardly as entertaining as a bombastic loud spectacle. The same way we animators have to exaggerate and push poses, film makers and video game designers push and break the laws of physics. From sounds to explosions and even fire, video games and movies take liberties with the rules of physics in order to make a more entertaining and engaging experience.
Take Star Wars for instance, during one of the final scenes in the movie, in which the rebels attack the Imperial battlestation the Death Star. We'll start with this scene because it takes the most liberties with vacuum physics:
The loudest vacuum ever.
First, the physics of sound: Sound is carried when air molecules travel through matter and collide with other air molecules. In the expansive vacuum of space there are very few molecules and they are few and far between, so they have to travel very far and seldom collide, making space silent. Characters inside the Death Star would hear sound because of the vibrations but on the outside all those explosions would be silent.
Speaking of explosions, there are a lot of them in the Death Star scene. Some of the rebel ships even catch on fire. Hollywood likes to treat explosions in space very similarly to how they treat them on Earth (which they also get wrong), as very large fireballs. In space however there is no oxygen to keep a fire sustained. An explosion would just be a bright silent flash before it gets immediately snuffed out. Either that or the ship would just break apart. That said the Death Star attack sequence is one of the most iconic scenes in film, due in no small part to how bombastic and entertaining it is, something it might lose had the filmmakers decided to go for a realistic approach.
A very similar scene is from the video game series Mass Effect. A series filled with technical jargon so one might get the impression they were taking a somewhat realistic approach, and in some ways they did but in many ways, it falls into the same issues. We'll be taking a look at the large space battle in the third game of the series It does a few more things correctly than Star Wars did, but not by much:
This brings us to the Halo series, which also makes a decent attempt at a realistic vacuum, but it fails in an entirely new ridiculous way. There are a few moments in outer space in the Halo series but we'll be focusing on the situation that occurs on Cairo Station at the beginning of Halo 2.
To understand the physics in this situation, we'll first take a look at exactly what Cairo Station is. Cairo is a space station in geosynchronous orbit around the Earth, named such as it is positioned above the city of Cairo, Egypt. It's main function in orbit is as an Orbital Defense Platform; It is a Magnetic Accelerator Cannon (MAC), essentially an absurdly huge railgun.
It is quite literally a gigantic gun in space.
In the situation we'll be talking about, Cairo comes under fire and the Master Chief is tasked with defending the station. At one point he leaves and is outside in the vacuum and basic physics are thrown out. This small clip highlights the issue:
There are the usual vacuum issues such as explosions and fire in space, though to be fair they did muffle the sound effects, which was a step in the right direction. With this situation though, we're going to focus on the odd gravity going on here.
Ignoring the fact that when the gun fires the station stays completely in place (I'll give them the benefit of the doubt on that one), there is no force keeping the Chief on the deck. Even if he jumps he falls back down instead of floating off. I'll give them the benefit of the doubt again and assume that the because it is the future, that they've found a way to simulate gravity within the station even without centrifugal force (Much like in Alien). However, there is absolutely no reason that this would apply out in the vacuum of space. So while Halo gets a few things right, this gravity situation is so absurd that it overwrites it.
Ignoring the fact that when the gun fires the station stays completely in place (I'll give them the benefit of the doubt on that one), there is no force keeping the Chief on the deck. Even if he jumps he falls back down instead of floating off. I'll give them the benefit of the doubt again and assume that the because it is the future, that they've found a way to simulate gravity within the station even without centrifugal force (Much like in Alien). However, there is absolutely no reason that this would apply out in the vacuum of space. So while Halo gets a few things right, this gravity situation is so absurd that it overwrites it.
Oddly enough, Alien got a few of these things right. In scenes taking place in a vacuum, the only sounds heard are things that come in direct contact with Ripley's suit, in which you would hear the vibrations. Another movie that handles vacuums in a realistic way is 2001: A Space Odyssey. These two films are incredibly engaging so at least some section of Hollywood knows how it's done.
So while it is very possible to make a science fiction movie that is entertaining and engaging while still following the proper laws of physics, it's often much more fun (Not to mention easier, I'm sure that's a big part of it) to just take creative liberties. Chances are most people will enjoy the film regardless. It's just fascinating how so many of these films and video games decide to go the general same route with their space battles and generally treat vacuums as if they're still on Earth. I'm just saying that if they're going to take creative liberties with a scene, they should focus a bit more on the "creative" part of it.
