Science Fact or Cinematic Fiction?

Burning Physics: Combustion in the Movies

Since the very beginnings of human culture, we have been obsessed with fire. Heat is essential to comfortable living for human beings, and fire is an essential life-giving source of heat and also exciting, unpredictable and dangerous. It is no surprise then, that heat and fire are central effects in cinema, and seem almost essential to any action film. However, Hollywood often abuses the true physics of fire to create an image that is more compelling for audiences. Often, these abuses are subtle and do add to the entertainment value of the film. However, these glaring faults in physics on a base level separate viewers from the reality of the story, especially in films that otherwise keep a very sober tone. These problems in representing heat span across many genres of films, though the primary offenders are action and adventure films. Sky Captain and the World of Tomorrow, a 2004 film made in a manner referencing classic pulp films of the 40's and 50's shows some classical misuse of heat physics in its character's behavior around a heat ray gun. Volcano, a 1997 disaster flick about a volcano popping up in L.A., has many inconsistent dealings with the heat and lava of the titular volcano. But even No Country for Old Men, a dramatic, somewhat slow paced action drama, includes a common movie explosion that is physically unlikely. These are only a few examples of the failure of movie makers to consider physics in their movies, though it is difficult to deny the thrill in an explosion, with proper physics or not.

Sky Captain and the World of Tomorrow is a film that uses a tremendous amount of special effects. This 2004 homage to classic pulp films with Jude Law, Gwyneth Paltrow and Angelina Jolie is an interesting visual spectacle, though not exactly a major box office success. Jude Law plays the protagonist, Sky Captain, the leader of a band of mercenaries flying World War II era fighter planes in defense of a world that seems right out of the Superman cartoons of the 1920's. Gwyneth Paltrow plays the requisite love interest and aggressive female reporter Polly Perkins, a staple of the genre. The physics in error come not from the major characters, but Sky Captain's best friend and technical genius, Dex, played by Giovanni Ribisi. Dex spends the majority of the movie figuring out the enemies plans, building secret weapons for Sky Captain, and even, in a deviation from the stereotype, getting kidnapped. However, in Dex's first appearance on screen, he is working with some kind of ray gun. No one would complain about the physics of the ray gun itself, the circular white rings spraying out of the elliptical device are just as campy as they ever were in Flash Gordon, but that is not the error in the scene. Dex tests the device on a block of Iron or Steel, which melts like butter under the gun's ray. Dex then walks over to the block and sticks his face right next to it without protection. Iron and Steel start melting at about 2500 degrees Fahrenheit, and the speed of the melting implied this block was hotter than that. While it may not have been fatal, it is inconceivable that Dex wasn't at the very least uncomfortable, but the film takes no efforts to convey that. So Dex is apparently more than just a technical genius, but impervious to heat.

In the late 1990's there were a series of Volcano-related disaster movies, that were a large part in the popularization of the disaster movie genre. Volcano, with Tommy Lee Jones and Anne Heche. Tommy Lee Jones plays a disaster management official, Michael Roark, who has a snarky romance during the disaster with geologist Amy Barnes, played by Anne Heche. While the idea of a volcano popping up in the middle of Los Angeles is far fetched to begin with, Volcano is well known for its utter disregard of earth science in it's presentation. However, there are also quite a few misrepresentations of heat in the movie, though one might expect that from a movie that involves people fighting back against lava. In a climactic moment midway through the movie, the survivors and rescue workers have dammed a river of lava with concrete freeway dividers, and they call in helicopters to pour water on the lava, so that it will crust and self dam the rest of the lava. With triumphant music blaring, the helicopters swoop down pouring thousands of gallons of water onto the lava. Billows of steam pour off the surface of the lava as the heroes cheered to celebrate their victory. However, it is fortunate that this was a movie, because this exact moment would result in screams not cheers. The water hitting that lava would cause the steam pouring off it to be extremely hot; so hot that it would likely scald to death anyone immersed in it. So all of those policemen and firefighters, Tommy Lee Jones and Anne Heche would all be seriously injured or killed by their own plan. But thankfully, the director chose to not kill all of the major characters, and the story continued on. Also, later on in the movie, a character heroically leaps into lava to throw an unconscious man to safety. After jumping into the lava, he not only does not light on fire, but stays standing melting from the ankles up. This and other physics errors may mar the reality of the movie, but that does not stop Volcano from being a favorite of many disaster movie fans, and a classic of the genre.

Although it has a few action scenes and involves quite a bit of violence, No Country for Old Men does not really deserve the title of “action movie”. The deep characterization and introspective nature of the film, as well as the themes of identity and fate that thread through the story are more reminiscent of a dramatic film. However, the plot of the movie nonetheless is the story of an assassin attempting to hunt down and kill the protagonist who has stolen a bag full of drug money. The assassin, Anton Chigurh, played by Javier Bardem and the sheriff chasing him, played by Tommy Lee Jones are truly the central characters of the movie. Anton's twisted ideas of fate and humanity, reflected by his use of coin flipping to decide if people live or die, as well as a cattle killing bolt driver to kill his victims is distinctive. And that is played against the moral quandaries of the aging Tommy Lee Jones, on his last case before retirement, to create the true tension of the film, despite the backdrop of an action plot. Although a much more serious and dramatic film than the first two examined, No Country still plays the Hollywood card in its dealings with heat and explosions. In a scene featuring Anton, he sets a cloth on fire stuffed in the gas nozzle of a car. The ensuing explosion provides a distraction so he is able to steal from a pharmacy. Though this seems a common occurrence in movies, the simple fact is that dropping something on fire into a gas tank will not necessarily cause a car to explode. Gasoline requires a significant amount of oxygen to react enough to cause a powerful explosion. So the only way the car would explode is if it was almost empty and it had just been turned off, so the gasoline was mostly mixed with the air in the tank. So even a movie not inundated with special effects can be sloppy in its use of physics.

These movies incorporate several genres, from a classic pulp sci fi movie, a disaster movie, to a serious dramatic action movie. All of them also have varying levels of believability, from laser guns and robots, to just a simple car explosion. And yet all of them have changed the physics of heat to suit the story. From humans that can handle thousands of degrees comfortably, steam that cools instantly, to mysterious explosions, the errors cover many different aspects of heat. And yet, all of those scenes are compelling, exciting, and riveting to audiences. Even without physical realism, fire, heat, and explosions captivate our attention. But anyone who has seen fire in person, from sparklers to wildfires to explosions, it is not necessary to break physics to show the power and beauty of heat. Movie makers could benefit from incorporating the real physics of fire into their movies, as the real stuff is just as seductive. However, even minus realistic physics, I will always gasp at a great explosion.

Term Paper 2 Outline

Burning reality: The physics of heat in cinema

I. Introduction

a. Draw-in: Fire. It's cool, though not literally. It's in movies.

b. Thesis: Combustion and heat are misrepresented in many movies

c. Essay Map

II. Body 1: Sky Captain and the World of Tomorrow

a. The melting point of steel

b. The melting point of human skin

c. Standing next to melting steel

III. Body 2: Volcano the movie

a. Humans melting

b. Pouring water on lava: death steam

c. 100 degree temperature change in two seconds

IV. Body 3: No Country for Old Men

a. Exploding car

b. Why cars don't actually explode when shot

V. Conclusion

a. Summarize

b. Restate thesis

c. Ending Statement: Fire is awesome.

Reverse Video Reference of Walking

Clip A - I had some real trouble with this one, I took six takes, this was probably the best. I'm not good at controlling my body when I'm off balance. Sort of sad since I'm a dancer, but that's how it is.

Clip B

Clip C

Clip D

Clip E - please ignore the sound, my family members were watching tv. I know the camera angle is off, but this was the only door I had to work with, so I tried to reframe it in such a way to maintain as much of the motion as possible.

Mid-semester Survey.

This is to certify that I completed the anonymous mid-semester survey for Art/Physics 123 and am requesting the five points of extra credit.

As a student at San Jose State, I understand the university's Academic Integrity Policy (http://info.sjsu.edu/web-dbgen/narr/catalog/rec-2083.html).

The Laws of Physics in an Animated Universe: Princess Mononoke

The Physics of the Forest: Princess Mononoke

Princess Mononoke is a japanese animated film created by Studio Ghibli in 1997. It tells the story of a young exile, Ashitaka, who wanders into a conflict between animal gods protecting a forest and a human town trying to mine the iron under the forest. He falls in love with a girl raised by the animal gods, San, who the villagers call Princess Mononoke. It is a highly acclaimed animated film, well known for its beautiful scenery shots and excellent animation. Many aspects of Princess Mononoke mirror the physics we know of our universe, with the exception of the magic of the premise, talking animals, gigantic animals, forest gods, and supernatural curses. In fact the animation of Princess Mononoke focuses on being similar to real life when it comes to character posing and local movements, but deviates sometimes when characters move through their environment. In particular, the character animation respects center of gravity very well throughout the film, even with characters that stand on highly raised wooden sandals. Also, inertia is represented accurately in gunshot impacts, hair that waves behind motion, and objects remaining stationary until acted upon. However, a clear difference appears that is common for japanese animated films, in which characters fall faster or slower in different jumps, and gravity is somewhat inconsistent in general. These gravitational differences often appear during action sequences to accentuate the motion being represented, but there is no clear slowdown to convey unrealistic action. Despite the technical differences, the action flows together smoothly and does not readily bring the viewer out of immersion.

It is clear that Princess Mononoke's characters operate under the same center of gravity properties that the physical universe follows. Even in our first introduction to Ashitaka, as he rides his elk along a raised stone wall, when he wants to move over onto the wall. He brings his feet up underneath him on top of his elk, and only then moves his center over to the wall. The motion clearly shows how his feet act as a base of support for his motion. Just a minute later, when a monster tears down a watchpost that Ashitaka and another villager are on top of, as the watchpost tips, both men lose their balance as their centers of gravity move outside of their bases of support. Later on in the movie, we meet a monk named Jigo, a short man who walks on sandals that have a thick wooden beam coming out of the center of the sandal. He stands on these wooden beams, and the animators often use this to play with Jigo's center of gravity. When standing still, Jigo crouches and puts his feet together, both bringing his center of gravity down and directly underneath his small base of support. He often totters back and forth, because when one leg is on the ground, Jigo's base of support is so small, so he goes off-balance. In one scene towards the end of the movie in particular, Jigo is attempting to catch a large iron container rolling down the hill. He stands with his legs wide to maximize a base of support, but when the container hits him, it moves his center of gravity backwards out of his base of support causing him to roll backwards down the hill. In an attack on the village, Princess Mononoke rides a wolf up a hill towards the town standing on the wolf's back. As the incline becomes more steep, the princess moves her body forward, keeping her center under her base of support to stay balanced. This same quality is prevalent through all of the human characters, throughout the film. It is clear that correct center of gravity was a priority for the animators.

On the other hand, gravity is certainly not the same in the world of Princess Mononoke. In one scene in the movie, San, also called Princess Mononoke, attacks the village of Irontown at night. After scaling the wall, she perches on the log wall in front of one of the village guards. The guard attempts to smash a large wooden staff into San, and in response, San hops sideways to another spot on the wall. This hop occurs over the course of 8 frames, and goes about four feet in the air. A jump lasting eight frames would be about 5.3 inches in the physical universe, so it is clear San is acting under a much heavier gravity. A few seconds later we see another example when San jumps about nine feet in the air over to a rooftop and gravity acts completely different from the short hop on the wall. She falls nine feet in nine frames, which is the same time it takes something to fall two feet on earth. Ashitaka, the hero, is also affected by this heavier gravity. Chasing San across the rooftop, he jumps and falls from an apex for about three body lengths over the course of 18 frames. Estimating his height at a conservative five feet, that is 15 feet over 18 frames. The 18 frames would correspond to about 9 feet of falling in earth gravity. However, this is not completely consistent. Just a few seconds after the short hop, San jumps off the outer wall to avoid a gunshot. After reaching her apex she falls for about 20 frames, but it seems to only be ten to twelve feet. This is quite a bit closer to the earth distance, about 11 feet. Later on in the movie, Ashitaka jumps off a cliff, followed by a giant wolf. He falls for 18 frames the same as before, and at first the angle makes it hard to make a good estimate of the distance. However, the wolf following him is about eight to ten feet long. It takes four long strides to make it down the cliff, running along the side. If we estimate the running stride of a wolf to be about one and a half times its body length, that is between 48 and 60 feet. So over the same time of 18 frames Ashitaka fell about fifteen feet at one point and about fifty feet at another. So San is acted on by a heavier gravity than earth at times, and almost normal at others. Ashitaka on the other hand, encounters an even heavier gravity later in the film. It is clear that gravity is quite fickle within Princess Mononoke's universe.

The other physical property of Princess Mononoke's universe that is noticeable is the inertia that is mostly the same as earth inertia. Ashitaka, San, and another character, Lady Eboshi, all show inertia in the waving of their hair as they move. One scene involving a fight between Lady Eboshi and San has several shots of the two women's faces, and the waving of the hair due to inertia is very obvious. Gunshots are also a clear example of inertia in Princess Mononoke. Ashitaka is shot through the chest with a rifle, and because the shot penetrated straight through Ashitaka, the force did not knock him down. Later on, when Lady Eboshi shoots enemy commanders on a battlefield, the shots do not penetrate the men, so the force knocks one off his horse, and the other gets knocked to the ground. In another projectile example, Ashitaka's arrows follow some of the same properties. Ashitaka has superhuman abilities from a demonic curse placed upon him, and so his arrows regularly decapitate or dismember his opponents. Because they are somehow cutting his opponents, the arrow does not exhibit very much force on the entire body of his targets. In an early action scene, Ahitaka's arrow cuts off his opponent's arms, leaving the man standing bewildered. While certainly done for comic effect, because the action separated the arms from the rest of the body, it is realistic that the man would not be knocked over by the attack. In a similar manner, Ashitaka beheads several horsemen throughout the movie, only to have their bodies stay riding for a few seconds before sliding off the mount.

Princess Mononoke is a stunning movie, filled with amazing artistry and intricate animation. The center of gravity that the characters display gives the movement a realistic feel and a natural flow. Also, the inertia shown both helps convey realism and accentuate the action and drama of the involved scenes, and even creates comic moments at times. While the gravity affecting the characters does change throughout the movie, and the action scenes are filled with superhuman jumping and falling off of cliffs, it is handled in such a way that it is not immediately noticeable. It does not pull the viewer out of the reality of the story, and helps create a grand sense of scale within the film. Princess Mononoke is a captivating animated film, a testament to the unique impact that illustration and motion have as a medium, and proper physics are an important part of that impact. Without using good center of gravity poses and representing inertia the way it did, the movie would not have been as immersive or as beautiful as it is.

Note on deviation from outline: After I began writing the paper, I decided that I didn't really like my plan at all. Moro is a wolf god within the story, and it seems you could sort of explain away deviations in her falling with the "she's a god" argument, so I really wanted to focus on the human characters for that analysis. Also, the last section on friction really wasn't turning out to be as convincing as I originally thought. The motion of the arrows was interesting and I wanted to say something about it, but I was trying to say that it the arrows should have been tearing instead of cutting, and the whole "demonic curse" thing was making that argument a little sketchy. Then re-watching some scenes I noticed how dynamic the representation of inertia was, especially in the hair waving, so I went with that instead.

For the sake of completeness, I'll go ahead and write a new and improved outline.

Physics of Princess Mononoke

I. Introduction

a. Short movie summary

b. Thesis: Princess Mononoke preserves realistic character posing, but fluctuates gravity.

c. Essay Map

II. Body paragraph I: Center of Gravity

a. Ashitaka

i. jumping from elk to wall

ii. falling off watchtower

b. Jigo

i. walking on stilts

ii. falling from container

c. Princess Mononoke

i. surfing on wolf.

III. Body paragraph II: Falling

a. Princess Mononoke

i. hopping along wall

ii. jumping across rooftops

b. Ashitaka

i. jumping across rooftops

c. Contradictory examples

i. San jumps with earth gravity

ii. Ashitaka falls with extra heavy gravity

IV. Body Paragraph III: Inertia

a. hair waving

b. gunshots

c. Ashitaka's arrows

V. Conclusion

a. Essay Summary

b. Concluding Remarks

Outline of the First Term Paper

Physics of Princess Mononoke

I. Introduction

1. Thesis: the Physics of Princess Mononoke are often correct in regard to center of gravity, but friction and gravity behave in a different manner than in the world we live in.

2. Summary

II. Body Paragraph 1: Center of Gravity

1. Ashitaka's center of gravity analysis

2. Jigo the Monk's center of gravity analysis

3. Princess Mononoke's center of gravity analysis

III. Body Paragraph 2: Falling

1. Moro the Wolf God's falling analysis

2. Princess Mononoke's jumping analysis

3. Competing Hypothesis for falling and jumping

IV. Body Paragraph 3: Friction

1. Ashitaka's arrows

2. Dismemberment

V. Conclusion

1. Thesis Restatement

2. Ending Summary

3. Conclusive Remarks

Stop Motion Animation of Falling

Above is 24 frames per second

Above is 10 frames per second

So, I wanted to use something that didn't just fall straight down, but also stayed mostly planar, so that I could do the stop motion on the floor. After I chose the toothbrush, I used the inches = frames^2 * (1/3) to determine where the center of the toothbrush would be at each frame on the animation, then I used shooting on twos since there were only 10 frames under my calculations. The position in rotation was chosen based on video reference, but it wasn't as precise as I'd like, because my video was pretty low resolution. I think because of the rotation, it would have benefited from shooting every frame, but I think it works as is.

It occurred to me that it was hard to see, since this was only over 2 feet, so I included a version slowed down to 10 frames per second, as well as the normal 24 frames per second, call it director's slowdown for effect.