Vibranium is some seriously useful stuff. A fictional ore from Marvel comics that comes from the African nation of Wakanda (also fictional) by way of a meteorite, Vibranium’s used in Captain America’s Shield, the Panther Habit, daggers, and a host of other places because of its unique properties.

It doesn’t exist in our world, but we wanted to know which materials that do exist in our world might have all or some of the properties of Vibranium. So, of course, we reached out to Professor James Kakalios, author of The Physics of Superheroes, to help us out.

“It has the property of absorbing all vibration,” says Kakalios. “So if you strike it, it absorbs the energy and, presumably, does something with it.”

Kakalios points out one very important thing we need to remember for the purposes of this discussion, and that’s the law of conservation of energy: energy cannot be created or destroyed.

With that in mind, we’re going to examine Vibranium largely in the context of Cap’s shield, which is actually a steel-Vibranium alloy. Steel makes the shield stiff and rigid — great for standing up to heavy blows and for causing damage when thrown — but the Vibranium keeps the force from said heavy blows from transferring to Cap. The materials work in tandem, allowing Captain America to protect himself with the shield and use it as a weapon.

A key element of Vibranium is the way in which it absorbs vibration. Knowing what we do about the law of conservation of energy, that vibrational energy has to go somewhere. So would happens to it?

Kakalios points to a specific scene in The Avengers in which Thor’s hammer, Mjolnir, hits Cap’s shield and results in a bright flash of light. Why is this significant?

Because it speaks to the possibility of the conversion of energy from vibration to light.

“If somehow we could turn all of the shaking of the atoms, the vibration of the atoms, these pressure waves that are set off due to the energy blast that the shield was absorbing, and convert it into light, into photons of energy,” says Kakalios, “that would still satisfy the rules of conservation of energy and it would be an effective way of absorbing the vibrations, of making a real type of vibranium.”

That leads us to our big question in this conversation: Is that possible?

Totally. The phenomenon is called sonoluminescence” and it’s very real. The clip below demonstrates sonoluminescence by passing sound waves through a bubble in a liquid container, causing the bubble to expand and subsequently collapse. When it collapses, the vapor molecules in the bubble rush together and give off heat and — you guess it — light. A bright, blue light.

We can’t exactly put this to use on a shield, but the theory is sound (literally) and it’s pretty damn amazing.

Where does that leave us for materials?

To illustrate the behavior of something like Vibranium, Kakalios talks about dropping a bowling ball out of a window. If you drop the bowling ball on pavement, you get a crack. If you drop it on sand, though, you get a crater. Why?

“Because the sand, made up of these grains that are free to move, the energy of the falling bowling ball is quickly spread out over many, many grains of sand,” says Kakalios. “The fact that the sand has these many different degrees of freedom and it can spread the energy out easily makes it a very good shock absorber.”

So does that mean we should have shields made of…sand?

Not exactly. But it does give us the idea of the properties we’d need to see in the atomic or particle structures of a material in order to make it a viable substitute.

Kevlar’s an obvious starting point. Made of long-chain organic molecules, Kevlar is perhaps most notable for its use in bullet-proof vests.

“What happens is that these long-chain molecules, because of the unique aspects of their chemistry, they lock into place to form very rigid structures,” says Kakalios.

Kakalios explains in terms of metals like lead and steel.

“Steel, lead, things like that have a certain resistance to bullet because the atoms involved are very big and heavy and thus it takes a lot of energy to move them,” says Kakalios. “Kevlar uses lighter-weight atom, but because of some unique chemistry and the way that they all lock together in a very rigid structure, it’s very hard to break those bonds and to get the atoms to move out of the way.”

Even stronger than Kevlar is graphene , which is made up of bonded carbon atoms. Super thin and capable of being more bullet-proof than steel when layered, graphene is powerful stuff. It’s real, and it’s a part of comic books, too.

Last year, Kakalios wrote an article for WIRED called The Magic Bulletproof Material That Made Iron Man Give Up Iron. That material? Graphene, of course.

Though we’re not exactly making big sheets of graphene for Vibranium-like purposes just yet, it’s perhaps the closest thing we have to real Vibranium.

“Because all the bonds are super strong within the plane of graphene…so it’s very hard to break them,” says Kakalios.

The other standout element? The speed of sound in graphene is super fast compared to other materials.

“So that means when you come in with some kinetic energy from some impacting projectile,” says Kakalios, “that energy gets the carbon atoms vibrating, but because the speed of sound is so fast, the vibration energy gets spread out very fast over the plane of the graphene and the energy then gets diluted and so it doesn’t have a chance to sit still and break the chemical bonds holding the carbon atoms together, and if it can’t break the bonds, then the bullet’s not getting through the material.”

What does that mean for our IRL Captain America Shield? It’s hard to say, but graphene presents some interesting possibilities. The same way that machine components and drill bits are diamond-coated, Kakalios muses that a graphene coating may prove an potentially significant wrinkle.

“I wouldn’t want to predict that all you needed to do was coat a steel shield with graphene and you’ve got Cap’s shield,” says Kakalios, “but it would be one avenue worth pursuing.”

Let’s not stop there, though — graphene’s probably the best material we have for a real-world equivalent of Vibranium…for now. But there are people working on nanocomposite structures and developing materials that use nanoparticles that act like the sand from the bowling ball-dropped-out-of-the-window example.

“What people are doing is creating structures that have other little nanoparticles within them, and when the energy comes in from some sort of blast or some sort of collision, the energy gets spread out over the nanoparticles,” says Kakalios. “They can spread out the energy over many many atoms so that no one atom has to bear all of that burden and so you dont break any chemical bonds or create any cracks.”

The possible applications of materials like these? Better armor, for example. Sounds like it’s straight out of comic books, doesn’t it?

“It absorbs the energy of the ball and quickly spreads it out. It doesn’t convert the energy into photons of light, but it spreads it out overmany degrees of freedom so that no one atom suffers a catastrophic break.”

While we’re not quite at the stage of SSR-issue Vibranium shields just yet, materials like developing nanocomposite technology, kevlar and graphene give us some of the properties we see in Vibranium without the help of extraterrestrial meteorites. Sure, Vibranium’s fictional, but some of its properties can be found in the real world, and that’s pretty incredible.

Photos via Marvel