The Physics of Earthbending

The Physics of Avatar: The Last Airbender and The Legend of Korra

Let’s continue our journey into the physics of bending with the element of substance, earth.

I recommend you read my first two posts on the physics of Avatar and Korra if you haven’t already. They’ll be important for understanding the rest of this series.

Moving Earth

Since we’ve hypothesized that benders get they’re powers from control over electromagnetism, we need to decide whether earthbending has more to do with the electric or magnetic side of the force. Since the type of metals we see some earthbenders moving are more magnetic than rock and we know metalbending is much more difficult than traditional earthbending, we can assume earthbenders aren’t just using magnetic fields to move the earth. That leaves electric fields, which not only explain how earthbenders move earth, but why it’s harder for them to bend metal.

My hypothesis is earthbenders create strong electric fields that force a percentage of negative charges in the rock they’re bending away from them deep into the Earth, leaving behind a net positive charge. This process is called charging by induction. An earthbender would then just need to move the source of the electric field so that the now positively charged earth would be attracted to it and moved in its direction. This way of earthbending would have more permanence in earth than metal because once the electrons have been forced to move, they will have trouble moving through the less conductive earth in order to eliminate the charge gradient.

Importantly, Earthbenders would still need to keep some of the charge they move continuously in motion. In other words, they’d need to use a balance of magnetic and electrostatic forces. This is because electrostatic forces on their own cannot establish stable equilibrium, meaning they wouldn’t be able to hold a piece of earth still in midair like we often see earthbenders do.

Seismic Sense and Truth-Seeing

Earthbenders could use the same process they use to bend earth to sense vibrations in it. If an earthbender charged the earth around them so that it felt the force of their electric fields, the electric fields would also feel the force of any motion already occurring in the earth. So if an earthbender created an electric field within their own body, they would be able to feel the motion of the newly charged earth. As we see in the shows, this motion would be caused by anyone moving on, in or bending the earth. Some earthbenders can even tell if someone’s lying by sensing the change in their breathing and heart rate through the Earth.

Lavabending

Lavabending is fairly simple to explain now that we understand earthbending in general. To melt rock, an earthbender just needs to apply enough pressure to it using electric fields so that it heats up and becomes liquid. To move lava, earthbenders would just use charging by induction like they do with typical earth. Of course, it would be more difficult to force the charge separation in lava because lava’s high temperature would make it more electrically resistive. That means it would be harder to get the electrons to flow out of the lava in the first place. This fits with lavabending being a rare skill.

Metalbending

Metalbending works not by bending the metal itself, but the particulates of earth in the metal, which means earthbenders can’t bend refined metals. Since the metals being bent in the show are more conductive, electrons would flow through them more easily. That means that earth benders trying to create charge gradients in the metal would need to constantly keep the electrons in the metal from just returning to equilibrium. That could be why metalbending is harder and why an earthbender like Toph, who is used to paying very close attention to the material she’s bending, would be more skilled at it.

There is also an interesting way earthbenders could make it easier to tear metals apart and fuse them back together. Metals are held together because electrons flow freely between their atoms. Earthbenders could fuse separate pieces of metals by forcing electrons to flow between them. Fusing metal with electricity this way is called arc welding. Earthbenders could also control the flow of electrons so that electrons wouldn’t move as easily between two regions of metal. This would weaken the metallic bonding between those regions and make them easier to separate.

Drawing Energy from the Earth’s Core

The Earth’s interior is not static. Latent heat from the Earth’s formation rises from the core to the surface where it can radiate out into space as infared radiation. To get from the core to the surface, the heat creates convection currents in which hotter material in the mantle slowly rises to towards the crust while cooler material sinks back down to be reheated. This motion also causes motion of the tectonic plates in the Earth’s crust. As I discussed in my post on waterbending, benders could likely use the same process they use to impart energy to the substance they bend to draw energy from it as well. In the case of earthbending, the benders would simply need to create charges in the earth and in their own bodies, and then the natural motion of the charged earth do to Earth’s cooling would provide a source of energy for earthbenders by pushing or pulling against their electric field. Similar to waterbenders, earthbenders would need to draw energy over a vast area in order to gain a significant amount, but this idea fits well with the concept that benders need to truly connect with their element.

That concludes our analysis of earthbenders.

In my next post, I’ll diving into the fascinating physics of firebending. As always, let me know anyways I could improve my hypotheses from this post or better explain them. See you next time.

Works Cited

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