The Laws of Physics in an Animation Universe

            You love a good movie, right? Of course you do—we all do! And I have no doubt that you have very good taste, at that. So what makes a good movie? Obviously, the most important thing is that the story has to be good. Also, the characters have to be relatable, the settings have to work in context, and the action has to be believable. This last one is key. Although we tend to overlook it when it’s done right, we can often tell when something feels off. So with that in mind, let’s explore the physics in the world of Avatar:

            What? No, not that one. While James Cameron’s ‘Avatar’ was truly a groundbreaking film—and presents a whole slew of physics I could talk about—I’m going to go with something a little more fun; Avatar: The Last Airbender

            No! Definitely not that one! To review M. Night Shyamalan’s monstrosity of an adaptation would require watching it again, and once per lifetime is far more than enough for me.

            Ah, here we go. That’s more like it. This is Aang. He’s the star of our show today, with a little help from these guys:

            Their series—Avatar: The last Airbender— was aired on the kid-targeted network Nickelodeon. It had 61 half-hour episodes in 3 seasons, and ran from 2005 to 2008. Ok, so it’s not really a movie after all. But a great TV show is just as good. I will be pulling examples from multiple episodes to answer the great mysteries of physics in the Avatar universe. Before I can do that, though, there’s something you should know: Magic. Although it’s not magic, not really—It’s called bending. This bending introduces a new natural force, and does have a quite significant effect on the physics of the world. Most objects and actions NOT associated with bending stretch the laws of physics, but remain believable. Many, but not all, actions associated WITH bending deliberately break them.

So what is this magical bending, and how does it work? Well, people with the ability, called benders, can “bend,” or manipulate one of the four elements: Water, Earth, Fire, and Air.

Bending does not always necessarily follow the physics of our world, but does follow what I would consider logical. In Ba Sing Sei the mysterious Dai Li, use earth bending to cling to solid wall faces. Geckos can do this in real life, but humans can’t. There has to be a whole lot of friction to balance the force of gravity. The Dai Li get around this problem by literally willing the earth wall to hold them up, just like willing a rock to levitate without touching it.
There are particular types of bending that actually do follow real-world physics.. While fighting Zuko, Aang uses Airbending to change his trajectory and dodge a blow mid-air. Newton’s third law of motion states: for every action, there is an equal and opposite reaction. When Aang created a blast of air going in one direction, the air also exerted and equal and opposite force on him. He was pushed away from his air blast, successfully dodging.

            Ok, in real life, pick up a rock. And no, unfortunately you cannot use earth bending to do it. Now pick up a heavier rock. Which is harder to lift? Obviously, the heavier one is harder. Well, it works exactly the same in Avatar. Heavier objects, such as large rocks or large amounts of water, take a great deal more effort to bend.

There is a counter argument to the logic: One of the largest deviations from believable physics is fire bending. In the Avatar universe, fire exerts a physical force. Disposable crewmen hit by fireballs are thrown back, as if struck by a solid object. Fire benders often use blasts of fire to propel themselves forward. In the case of strong fire benders, such as Azula, they can even fly.

This should not be possible. Fire is pure energy. It exists as the breaking of chemical bonds in its fuel source. It should not be able to exert a force its own.

            Now let’s take a look at the gravity of the situation. Falling and flying both happen a lot in this series. Usually, it’s Sokka (the comic relief of the group) falling and Aang flying.

            And here’s how well one one of Sokka’s comical falls turned out. Before he got stuck in a hole, however, Sokka fell in a parabolic arc. Proper arcs occur throughout the series. Thrown objects follow realistic arcs (except Sokka’s boomerang. More on that shortly), though not always realistic timing. Aang uses airbending to jump many times higher than he should be able to, but also follows parabolic arcs.

Often though, rules of gravity are broken. As Sokka exclaimed, “I’m just a guy with a boomerang. I didn’t ask for all this flying and magic.” Sokka is decidedly the least-magical member of the group. But that boomerang, though… I don’t know much, but here’s my best reasoning (based on the class so far, plus some internet research); The return factor of a boomerang is dependant on the forward motion (inertia) as well as the rotation. The top wing travels forward and the bottom wing travels backward as it spins. Although they are rotating at the same speed, the wings are traveling through the air at different speeds. This brings into play the Magnus effect, which is aerodynamic lift produced by an object’s spinning motion. It creates pressure from the side at the top of the spinning boomerang, causing it to turn. To return completely, the flight must not be interrupted. But at one point, Sokka throws it at Combustion Man. It hits, then Sokka catches it. What?

            When the boomerang struck an object, the lift caused by the rotating wings would have been dispersed. The unbalanced force (Combustion Man’s head) would have caused the boomerang to stop, and then gravity would have done the rest. But the story didn’t call for Sokka to lose it (yet!).

            Later on, Aang slows himself during a fall by twirling his staff and hovering like helicopter. According to Bernoulli’s Principle, the speed of the staff would cause its airspace to become lower pressure. Then the air pressure under Aang would be enough to exert an upward force. But Aang is not light enough. Think 12 year old boy, not ping-pong ball... It’s possible he was using a form of airbending in tandem with his trick. Another airbending oopsie occurs with Appa, the Sky Bison. It appears that Appa flies by being lighter than air (floating), but it is established that he is heavy while on the ground. He lumbers, and leaves deep footprints. I call shenanigans.

            There are both realistic and non-realist depictions of Inertia in the avatar universe. When the main characters go ice dodging, Sokka has to steer sharply to avoid hitting dangerous rocks. The rules of inertia call for Katara and Aang (in the back of the boat), to be thrown against the side of the boat, to the outside of the turn. Guess what? It happens. The boat suddenly turns out from beneath them, but inertia causes them to continue to travel in their original line of motion. Another good depiction inertia is when Aang bends the elements in an orbit around himself. His bending force acts as centripetal force, keeping the objects in. When he lets them go, they fly outwards away from him, following the rules of inertia. Zuko has a similar attack with fire.

            Here’s an example of “cartoon physics.” That is, a scene that deliberately breaks the laws of physics to achieve a comical effect. After a chase scene, Azula manages to stop at the edge of a drop-off—from a run— without her inertia carrying her over. Her arms flail wildly, but she regains her balance. This is in direct contradiction to Newton’s first law, which states that an object in motion stays in motion with the same speed and in the same direction until acted upon by an unbalanced force. There is no unbalanced force present, and Azula should have continued along her path of motion and fallen (as Zuko does when he charges through the door after her).

            The avatar universe is rich with possibilities, and I’m really glad the creators chose to structure them the way they did. I think the physics were presented in a very mature way, without relying heavily on gags and tricks. While there are times that laws of physics are broken for effect, these are used sparingly. The general physics, while not exactly like our own, are close enough that they are believable.

            I have wondered what the show would be like if they had use a more “cartooney” handling of physics. I think it would have severely detracted from the overall impact. The actions would not have seemed as important. The bending would have lacked organization and logic. Without the more serious approach to the physics, this could have been “just another kid’s show.” I was skeptical when I first began to watch it (I was already in college—far too old for cartoons), but I was amazed at how good it was, and I believe the handling of the physics played a part in that. If you subtract the “magic” (bending) effects, this series has slightly exaggerated, but still believable physics.