Physics vs. Magic

When Shrek came out, millions of viewers instantly fell in love with the tough, yet adorable, main character. Based on the overwhelming success of the first movie, Dreamworks Animation continued the story of this magical world with a few more creations, perfecting them visually as much as the technology allowed. Shrek the Third is an excellent family movie with very detailed graphics and extremely realistic animation. It is clear that the technology has advanced a lot since the first two movies; these advancements allowed the animators to construct a world that indeed feels very real, no matter how magical its inhabitants are. However, the perceived reality comes at a price: it is much easier to spot the deviations from the laws of physics that apply in our world. Clearly, Shrek’s magical kingdom is still governed by similar laws, but they are definitely very different from what we would expect. An observant viewer will notice the unusual application of the law of inertia, special properties of gases and liquids, and the fragility of some natural materials. While the first instinct may be to attribute these differences to magic, a true scientist should always look for a logical explanation. As the next few paragraphs will show, magic plays a very minor role in explaining the observed deviations; it could only be seen as a compensation mechanism for some physical anomalies.

According to Newton’s first law, an object tends to remain in the same state unless an external force is applied to it; thus, an object at rest will tend to remain at rest. However, this fundamental law does not appear to apply in Shrek’s universe; on the contrary, various objects at rest appear to come to motion or change the direction of their movement with little or no external impact. When Shrek and his party arrive at the Worcestershire Academy, the scene with jumping cheerleaders would strike the viewer as a very odd one. The girls make incredible cartwheel jumps and move at an unrealistic speed, but they do not apply any visible muscle force. Just to change the direction of a jump like this in the real world would take a lot of effort and visibly bend one’s body. It seems like the fantasy cheerleaders simply lift their bodies from the ground to escape the friction force and then guide the natural movement with a very little effort. In another scene that supports this theory, a group of small animals and magical creatures try to barricade the door when the castle is under attack. Three little pigs, a feminine wolf, a wooden puppet, and a cookie man move fairly large furniture as if it is made of air. A creature that is no larger than a mouse moves a giant throne all by itself; it seems that no effort is needed aside from giving an object a gentle notch in the right direction, once again, to overcome the friction. Yet another example of this behavior can be seen at the ball when Shrek’s buckle belt snaps off and flies at an incredible speed in a straight line. It then proceeds to gently bounce off the donkey’s head and a series of other objects until finally hitting the floor and remaining there. From all this evidence, it is reasonable to conclude that the objects at rest tend to move on their own accord; friction is the main reason for the objects to remain stationary.

Some of these observations can also be explained by very low gravity; such a condition would indeed make it easier for objects to be lifted off the ground and fly longer distances before dropping. However, several examples contradict this alternative theory. For instance, the jumping cheerleaders come down just as quickly as they would in real life; if the gravity was indeed low, they would jump much higher and stay in the air longer. When attacked by pirates, Shrek unsuccessfully tries to lift a small cannon in order to save his friends; it does not make sense that a big and strong ogre cannot move this object under low gravity when tiny creatures have no problem moving the furniture that is many times their size. Overall, the low gravity does not appear to be a plausible explanation for all the observed deviations. It is much more likely that the first law indeed does not apply, so the stationary objects do not tend to stay at rest.

Aside from the unusual application of some fundamental laws, many solid materials of Shrek’s world appear to have very different characteristics from what we expect in real life. Specifically, wood and stone are very fragile, but metal alloys are extremely sturdy. Near the beginning of the movie, Shrek lightly throws a glass bottle at a large sailing ship; the bottle easily makes a relatively large hole in the side of the ship with pieces of wood flying everywhere. It is clear from the scene that the wood is rather thick, so it should not break that easily. Furthermore, we had seen in the belt buckle example that other objects tend to change the path of their movement on impact rather than break through the material. Hence, the wood of this fantasy universe must be extremely fragile. This assumption is confirmed during the scene where prince Charming attempts to gather up some bandits at the bar; a fragile old lady snaps a thick wooden pool cue with no effort at all. Most of us would have to apply more force to break a plastic pen!

A similar anomaly happens when the princesses break out of their jail cell; the old queen takes down a stone wall by striking it with her head from the distance of just a few inches. The wall looks to be at least a foot thick, but just one small strike is enough to break the stone into bits and pieces; the viewer can actually tell that it is not just the mortar that cracks. To confirm that it is not just a coincidence, the queen takes down the second wall just as easily. After breaking through two walls, the woman looks a little dizzy, but otherwise unharmed; if the stone was as sturdy as in our reality, she would have sustained some visible damage to her skull. While it is unusual to make a wall out of such an easily penetrable material, the fantasy kingdom does not appear to be concerned with security; this explains why the negative characters can break in so easily.

Outside of the security related applications, builders seem to recognize the need to compensate for the unusual fragility of wood and stone. When Shrek and his crew arrive at the Worcestershire Academy, they see a large wooden drawbridge that is reinforced with metal; when the bridge drops open and heavily hits the ground, there is no visible damage at all. This implies that the metals of this world are extremely strong, so they are commonly used to reinforce weaker natural materials that are likely more abundant and easier to work with. We can see some proof of this theory when Doris uses her fist to easily smash a padlock that is hanging on the castle gate. The gate looks like it is made of metal; this is why it does not show any damage. The lock is likely made of wood, so it falls apart easily; this also supports our earlier assumption that the inhabitants of this world are not particularly concerned with their safety. However, they definitely appear to know that reinforcing stone and wood that are extremely fragile with much stronger metals is a necessity in this magic kingdom.

Similarly to the unexpected properties of solid materials, other regular looking substances of Shrek’s world are just as unique. Specifically, liquids appear to have an extremely low viscosity and gases exhibit a very low density.  Going back to the scene where Shrek sinks the sailing ship with a bottle, it is apparent that the damage is not sufficient to sink the ship that quickly. Based on the size of the bottle, the hole is about three feet across; furthermore, most of the damage is clearly above the water line. However, the entire ship sinks in less than five seconds. Given that it takes longer to fill up even a submerged empty bottle in real life, there is a clear deviation in the properties of water.  From this example, we can conclude that the water in Shrek’s kingdom has a very low viscosity, so it flows extremely quickly. We see further evidence of this property at the haunted inn when Stromboli empties a mug of beer into his mouth in a fraction of a second. Even though the mug is nearly empty, it is impossible for the liquid to flow that quickly even when applying a strong suction force in the real world. Based on this, we can establish that liquids indeed have a very low viscosity in this magical universe.

Similarly to liquids, gases do not appear to be as dense as we would expect. When the aerial attack on the castle begins, the witches and bandits sit on the flying brooms upright even at the visibly high speeds. In our world, they would definitely be thrown off by the aerodynamic drag. Since we do not see them bending down even a little, there does not appear to be any air resistance. The obvious explanation is that the air has a very low density in this fantasy world; the previously established fact that objects tend to avoid the state of rest explains how the witches are able to fly on the brooms. Since the nonexistent air resistance would cause the brooms and their passengers to come down to the ground, we can speculate that some magic is used to hold the flying objects in the air. After all, it would be inappropriate to explain the entire magical world in terms of plain physics.

Shrek the Third is a true masterpiece of the modern digital animation. The fantasy world looks and feels as real as our own, so it must follow a similar set of physical laws. These laws differ from ours to make the visual effects more interesting, but most deviations are consistent and explainable. After carefully studying Shrek’s adventures, a scientific mind would conclude that magical objects tend to move even without any external forces, wood and stone are extremely fragile, water exhibits the properties of a superfluid, and air has no resistance. These logical explanations almost make us forget that we are dealing with a magical world. However, as observed in our own world just a few centuries ago, magic comes very handy when trying to explain something that the modern science cannot comprehend just yet.