Science in movies and video-games

The physics of Iron Man

02/06/2018 ⋅ No comments

Par Timo van Neerden

The Iron Man movies are a Marvel franchise (part of the Marvel Cinematic Universe), with three parts (until now) released in 2008, 2010 and 2013. It stars the eccentric billionaire inventor Tony Stark who builds a intelligent and technologically advanced exosqueleton that allows him inter alia to use weapons and fly.

If in 2018 those things are pure science-fiction, the movies are showing interesting sciences facts, some of them that would make Newton, Faraday or Darwin turning over in their graves…

ironman ready to fire

About the speed of sound

Before talking about Iron Man in person, let’s talk about the beginning of the first movie. Tony Stark is in Afghanistan for a live demo of his last weapon: the Jericho missile. He tests it in front of American soldiers who are then blown by the shock wave of the explosion.

iron-man in Afghanistan
The science fact that is wrong here is the shock-wave: in the movie, it takes about 3 seconds to arrive to Stark and the soldiers. Shock-waves travel at the speed of sound: that makes the Jericho missile explode at roughly 1 kilometers away. In facts, the explosion that happen on the side of the mountains takes place much farther!

Taking into account the snow limit on the mountain tops with the snow limit of mount Kilimandjaro (or any other mountain in the world), we can assume that the mountains are about 6500 meters height (Afghanistan is in facts full of mountains, and some tops are above 7700 meters height). Also, judging with the absence of vegetation, Stark must himself be at about 3000 meters above sea-level.

Using some shots, like this picture that I assume was taken roughly 20 meters from Stark, and knowing that Robert Downey Jr measures 1,73 meters (5 feet 8 inches), the Thales theorem tells me that the explosion takes place 40 kilometers away.

Even if the explosion was the biggest explosion ever, a shock-wave only moves at the speed of sound. At such a distance, the shock-wave would hit Stark and the soldiers after 2 minutes. Not 3 seconds…

Well, let’s now discuss about Iron Man.

Using palladium as a energy source

All along the first movie, and the beginning of the second movie, Tony Stark's armors is powered by a palladium power-core.

Firstly, whereas Wolverine's adamantium, Captain America's vibranium or the unobtainium in Avatar are fictitious metals, palladium is a real material. It possesses the atomic number 46 and belongs to the precious elements, like platinum.

Secondly, the only possible hypothesis of creating a huge amount of energy with a little bit of matter is the nuclear hypothesis. The problem is that palladium is stable and would be a wrong choice for this… Using it in a fusion reactor (instead of a classical fission reactor) wouldn’t work either: in the case of palladium, it would consume more energy to fuse than it would produce. One might consider the anti-matter solution, but again, the efficiency would be very bad (it would be negative, actually).

The choice of palladium as the power-core for Iron Man comes possibly from Greek Mythology: the Palladion was a statue of Athena in an iron armor. Like Iron Man.

Melting the palladium

Prisoner in a cave, Stark uses a wood (or coal) fire to melt some palladium and forge his armor:

molten palladium
Palladium melts at 1554°C (2829°F), which is slightly above the melting point of pure iron.

A coal or wood fire can reach some 2000°C (3632°F), but only with controlled oxygen supply. In an open fire, the temperature is far from being sufficient to melt iron or palladium, otherwise, steel stoves would melt, right ?

Assuming that the fire is hot enough to melt palladium, it would then be at least at 1554°C (2829°F).
Therefore, the liquid metal would the white and luminescent. It would never have that metallic aspect. It’s Wien’s Law in thermodynamics: a body emits electromagnetic radiation, which wavelength depends on the temperature of that body.

A 1554°C (2829°F) hot metal glows in a white light. The human body at 37°C (98°F) also emits light, but in the infrared. That is why you can see people in the dark using an infrared-camera.

For the movie, they probably used a low melting-point metal, like tin (melting at 232°C/449°F), lead (328°C/622°F) or aluminum (660°C/1220°F). Better, they might have used gallium, which melts at as low as 28°C/86°F or even mercury (liquid at room temperature), but that last one, I doubt it since mercury is a highly toxic compound.

An armor from steel

The first version of Stark’s armor is made in a cave, where he is under pressure by terrorists and with rudimentary tools. He has only some steel and a few grams of palladium available.

Assuming (even we saw this is wrong) that one could extract energy from palladium: Stark says he can produce 3 gigajoules par seconds (which is 3 gigawatt) from the palladium in his arc reactor. At that rate, his arc reactor can last 5 days and 1/2 before all the palladium is converted into energy, according to the E=mc² equation.

He declares that his armor is also able to power “something big for 15 minutes”, which means that his armor requires 430 megawatts per hour: this is about half the power of one nuclear power-plant.
Also, even if his armor is super-efficient with only 1% of that energy being lost by thermal dissipation, that 1% represents as much as 2000 electrical converters of 2 kW each. This represents a lot of heat, enough actually to make his armor melt in seconds.

Well, for his credit, that armor had him escaped from a cave kept by terrorists in the middle-east, so he has done some nice work on that.


iron man propulsion
Elementary physics reminds us that "for each force there is an equal and opposite force". It is Newton’s third law.
It is this very principle that makes jet planes go forwards and rockets move to the moon. For the rocket to go up, it needs an opposite force that is stronger than gravity. In practice, that force is obtained using high-speed gases that are expelled downwards.

For Iron Man, it’s the same thing: in order for the suit to move upwards, it has to expel gases downwards. This seems to happen when we see dust and sheets of paper flying around when Iron Man hangs above in the air, during the first tests of his suit.

But where do those gases come from? In a rocket, the gas is water vapor that comes from the combustion of hydrogen and oxygen contained in the fuel-tank, but for Iron Man there is no gas production since the power of the armor comes from a nuclear device. Yet, we can notice some black smoke trails behind the flying suit: this is not very consistent.

Since there is no gas emission with a nuclear reactor, there remains the turbo-reactors option: a reactor that would suck the air from above and push it downwards. It’s basically what helicopters do. But again, this is not possible when, in the first Avengers movie, the suit is going in outer space where there is no air to propel or even underwater:

iron man underwater
Some websites or forums are talking about an Ion Thruster
Such an engine uses an electromagnet in order to accelerate ions (charged particles) and propel them. The propulsion of the device is then generated by the thrust of the ions.

This might work… providing that Stark has an enormous ions supply in his suit and an extremely powerful ion thruster: a typical thrust of such an engine is equivalent to 50 to 250 millinewton, which is as low as the force of blowing on hand with your mouth !
One would need about 4000 ion thrusters to lift one 100 kg man, without any armor and without the 500 metric-tons of ionic-fuel that would be necessary to all these thrusters.

The ion thruster propulsion hypothesis is therefore not viable. They only work in space, where there is no air resistance: the thrust might be very low, but if powered long enough it accumulates the speed and after some days, the spacecraft moves at literally astronomical speeds.

Iron Man’s suit’s propulsion like it is stared in the movies remains a mystery for science.

Oh, and concerning Stark’s acceleration: it’s about 13,7 g; one can do the math on that at the end of the third movie, when Iron Man saves the 13 people falling out of the presidential airplane, when the suit brakes right above the water (more math on that further in this article). At that stage, Stark should suffer from G-LOC when he takes-off from the ground.

The suit-case with the suit in it

Going to the second movie now. I pass the beginning, where we see a guy named Vanko (one of Stark's haters) making a fork of his armor using the same technology, also in his garage but with a parrot (I didn’t know that those tropical birds survived the low temperatures of the Russian winter…).

Let’s focus on the suitcase containing the suit:

ironman suitcase
At the ending of the first movie, we learn that the suit is made out of a gold-titanium alloy. Titanium is a quite light metal (two times less dense than steel), gold on the other hand is extremely dense (almost five times denser than titanium).

We can calculate the weight of Stark's armor. To simplify, let’s assume that the armor is 3 cm (1.2 inches) thick and is equally recovering Tony's body. A typical human has a body surface of 1.7 m² (18.3 ft²).
In order for Stark being able to fit in the suit, it has to be slightly bigger, but again, let’s assume that the armor has the same body-surface than a typical human.

The total amount of metal in the suit is thus 3 cm × 1.7 m² = 0.051 m³ (1.8 cubic feet). If we say that that volume is composed of 50% titanium and 50% gold, then the mass of the suit alone will be 607 kg (1338 lb), with 492 kg (1085 lbs) being gold and the remaining weight being titanium.

And even if the suit was only 3 mm (0.1 inch) instead of 3 cm (1.2 inches) thick, it would still weight as much as 61 kg (109 lbs). This is better, but still a lot to be carried around with one hand…

Conclusion: unless Happy is a super genetically modified weightlifter, the action of lifting the armor with one hand is not possible for an average human… But by the progress of science, all that stuff…

Einstein's field equation

A bit further in the same movie, Nick Furry hands some belongings over to Tony. That stuff belonged to Tony's father, including a notebook that Tony is reading. When he does so, we can see some mysterious equations :

einstein equation in ironman
On the page on the left we can notice an equation that actually is a form of Einstein’s field equation of the general theory of relativity. This equation describes the distortion of space-time as an effect of gravitation :

einstein equation
The real equation that you might encounter in books is a little bit different, because the equation in the movie is only an equivalent form. If we read decrypt the text around in the notebook, we see that it really is Einstein’s equation, in some particular cases.

The following pages are also interesting.
We find for instance a drawing of the tesseract (that will be the foundation of the plot in the first Avengers movie). Also we find something about spectral energy densities near strong gravitational fields, and a page mentioning the Zeeman Effect.

The Zeeman Effect is for magnetics fields what the Stark Effect is for electric fields, on spectral lines.

The Stark Effect is a real thing: it is for an atom to see it’s emission spectrum being altered by electric fields (magnetic fields for the Zeeman Effect).

It the movies, Tony's father, Howard Stark is the discoverer of the Stark Effect. I say that this is well played, don’t you?

The particle accelerator

Stark, using his father's unfinished research due to the lack of technology of his time, decides to create a new element. He builds for this purpose a mini particle accelerator, similar to the LHC in it’s toroidal shape:

particle accelerator ironman
Scientifically, Stark’s hacks are quite rough. First, the interior of the tube has to be empty (I mean, full of vacuum) and that takes at least several days or week in reality. If we want something as devoid of matter as ultra high vacuum (UHV), at the end, the atoms are removed one by one. One also needs to cold the device down to near absolute-zero temperatures, with liquid helium.

Moreover, building a particle accelerator requires some sort of power supply. Huge quantities of electricity, actually, and big power cords. So, unless Stark has several arc reactors in his garden and many tons of palladium (which might be the case), his little power-cord is totally useless.

Then, when he deflects the laser beam, logically, the beam should have stopped right after he begins to deflect it.

In principle, I don’t quite understand how one can use a laser to create a new element: in reality, the new “super-heavy” elements are created not with lasers, but by bombarding a chunk of matter with lighter (and faster) elements, like protons. These proton beams cannot pass through air without fading rapidly: they only exist inside the collider's vacuum.

Finally, you should know that all the super-heavy new elements (the ones at the bottom of the periodic table, after uranium) are unstable. If plutonium and americium are still usable (they materially exists), the other elements are so unstable that they only last for several micro-seconds before decaying.

The double pendulum

At a moment in the second movie, we have Tony Stark facing Pepper Potts, with a double pendulum toy on her desk:

ironman double pendulum
It’s the metallic thing, in front of him: it swings and oscillates in every direction. We can see it in action in this video clip.

In reality, this device exists but it is powered so that it keeps moving. Its operating principle is based on electromagnets.
A possible configuration, based upon the video, might be this: there are magnets at the end of both swinging sticks and at the top of the bearing sticks, there is also an electromagnet in the pedestal:

ironman double pendulum magnets
The magnet on the big stick, when it passes above the pedestal, is repulsed by the electromagnet. The electromagnet, electronically controlled, only activates right after the stick passed above it and begins to roll away from it, so that the stick is not slowed down but only gets pushed.

That electromagnets pumps energy in the system so that it keeps moving.

A double pendulum system without electromagnets can be mathematically described as a differential equations set with a strong sensitivity to initial conditions.
If we include the electromagnet and the forces of friction (including air friction) on the sticks, it is impossible to describe completely: the slightest disturbance makes the pendulum completely change is way and the final state: it becomes chaotic.

This toy can be purchased on the Internet for about $300, just by googling “iron man double pendulum” or “the swinging stick”.
The reason for such a high price might come from the precision deployed in the geometry of the branches and the forces of the magnets: they have to be balanced so that the motions looks smooth and clean. They must also be particularly durable to abrasion and friction.

Can we spit fire?

In the third Iron Man movie, we see some guys that have the ability to spit fire:

ironman fire mens
I don’t think that we would have that power one day in the future (we might have guessed that thought)

Even if there are animals that are poisonous without getting poisoned themselves, mastering fire is harder: fire is indeed far much destructive to living creatures. Our cells only are mode from carbon-based molecules and some water, so, as soon as the temperature reaches the boiling point of water, most living creatures are already dead.

On Earth, life has adapted to nearly everything: there are small creatures like cockroaches that can live without their head or survive the micro-wave oven for several minutes, or the incredible tardigrades. These little animals can resist the vacuum of space, huge pressures (1200 atmospheres), cold temperatures (−200°C/−328°F), hot temperatures (150°C/302°F), a water-free environment, a chemically strong environment (acidic/basic), cosmic rays, radioactive rays (1000 times the lethal dose for a human). This creatures have survived all five of the mass extinctions that the Earth has known and for over half a billion years. There is also no doubt that the tardigrades will survive humans too.

But even with all that resistance, they still do not resist fire.

What might one day be possible (if it didn’t already happen in the past), is that a species produces chemicals like hypergols: theses chemical instantly ignite in air. Some species might also secrete inflamable gases (like methane) and use some sort of trick to put it on fire, like a highly exothermic reaction, electrical currant (like the electric ell) or a mechanical trigger like the pistol shrimp, that uses its super-fast claw to generate a luminous cavitation bubble at a temperature exceeding 5000°C/9000°F.

In theses cases, yes, some animals would be able to breath fire, but we don’t find any of such animals on earth. Why?

Most animals do not act with any anticipation, they act instinctively. If an animal was able to use fire to defend itself against predators, it would not think before it does so, and the fire might hit threes or grass on the ground. The animals would quickly burn everything around him, including maybe itself or members of its own species, and eventually provoke its own extinction.
If nature and evolution might at some point have created some fire-breathing animals, they would never have been able to survive, not without having also a great intelligence allowing them to use the fire wisely.

Being intelligent enough to see when to use and to not use fire is not a widely spread-out feature in the animal kingdom.

Falling from an airplane

Still in the last movie, Starks finds himself on board of Air Force One when it is hijacked by the Mandarin's mens. The plane is depressurized and all the passengers are ejected. Iron Man then tries to catch em all:

ironman falling from a plane
First, according to the information provided by Jarvis, when he is right under the plane, Iron Man flies at 30,000 ft (around 10 km) above the ground. At that altitude, the temperature is a freezing −30°C/−22°F… I doubt that this temperature allows the stewardess dressed with a skirt to feel good about it.

Secondly, if someone jumps out of a plane flying at 30,000 ft, he would lost consciousness in a matter of seconds: air pressure is about 1/3 of the pressure at ground level, and the lack of oxygen is strong enough to by vital. Alpinists that climb Mount Everest usually use an oxygen mask to survive.

Thirdly, the terminal velocity (the maximum speed during a fall) for a human body lying horizontally is about 200 km/h (124 mph). The duration of the fall in the movie is almost accurate, but what is not may be the deceleration at the end, when Stark has caught everyone: he catches the last person at about 100 ft (30 meters) and at that altitude, he is still walling at 200 km/h (124 mph).

Stark brakes and slows everyone down during the last 20 meters (65 feet) of the fall. The Air Force One crew slows down from 200 km/h (124 mph) to 0 km/h (0 mph) in only 20 meters (65 ft). Everyone sustains thus a deceleration of 6.4 g ! This is the same as what someone would go through when he falls down and opens a parachute: it is a huge deceleration but it is not lethal nor impossible. But things get worse than that…

According to Jarvis, there are 13 people that Stark has to catch and is carrying: there are two “human chain” of 6 persons and the last one is on Tony’s back. Enduring 6.4 g means that you weight 6.4 times your own weight.
The stewardess on the top of the human chain and that is holding 5 other persons with one hand is enduring a traction of 6.4 times the mass of 5 people. If the 5 people have a average weight, she is holding not less than 2.2 metric tons. This represents 4 times the maximum traction that a human arm bone can endure before snapping in two parts. And I do not count the wrist or elbow that will surely break far before that.

This scene is therefore triply impossible, but not really because of the deceleration as I first expected.

To conclude

I really like the Iron Man movies. I love all that technology and Stark’s genius. However, in the real world we are still far away from what he is doing: the main problem is and will probably remain for several decades the needs for a more concentrated energy source. It’s maybe the only problem of this generation: we use energy from dead dinosaures and from uranium out the ground.

If we had some sort of energy source, like anti-matter, vaccum-energy or even perhaps something out of dark matter or something new, then we would have our power-suit, our clean energy and everything we want…

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