The Science of Allomancy in Mistborn: Iron and Steel

After taking a few weeks off while we moved across the pond, I’ve returned my research focus to investigating the science behind allomancy in Brandon Sanderson’s Mistborn series. As I mentioned in my first post regarding this research, the concept of iron pulling and steel pushing left its mark on my psyche, prompting me to wonder what sort of scientific basis, if any, there could be behind allomantic abilities. This week, we come full circle as I discuss those very powers that most appealed to me.

Lines of Blue

There are two aspects of iron pulling and steel pushing that need to be examined. The obvious one is the physical effect of these powers, allowing an allomancer to push or pull on nearby metal objects. But before we get to that, let’s look at the other effect that occurs when an allomancer burns iron or steel, as demonstrated the first time Vin experimented with those metals:

“When she did so, a very strange thing happened—a multitude of faint blue lines sprung from her chest, streaking out into the spinning mists. She froze, gasping slightly and looking down at her chest. Most of the lines where thin, like translucent pieces of twine, though a couple were as thick as yarn.”

While the exact mechanism behind this visual phenomenon remains hidden to us, the fact that these lines are blue, should not be surprising to those familiar with historical chemistry. There is a widely used compound made primarily of iron, Iron(III)-hexacyanoferrate(II), more commonly referred to as prussian blue.

Discovered accidentally in the 1700s, prussian blue quickly became the blue pigment of choice among artists, replacing the more expensive lapis lazuli (a material emphasised heavily in the Septimus Heap series by Angie Sage). It’s also interesting to note that prussian blue is also used as a treatment in metal poisoning, as it is a known chelator of certain heavy metals. While this fact may serve some role in protecting allomancers from the toxic effects of their ingested metals, we have no direct evidence for this theory.


Gravity and Magnestism

Let us turn now to the physical effects of these two allomantic abilities, the ability to push and pull on metals. From the descriptions we find in the text, we can immediately rule out magnetism as a mechanism for this ability (at least magnetism as we understand it). For example, while bronze isn’t normally affected by magnets, Vin and Kelsier both use their allomancy to propel themselves along a bronze spikeway leading between Fellise and Luthadel. 

If we rule out magnetism, the next likely candidate is gravitation. Since we know from Kelsier that:

“If you’re a lot heavier than your anchor, it will fly away from you…however if the object is heavier than you are…you’ll be pushed away…if your weights are similar, then you’ll both move.”

This seems in agreement with what we know about gravity, namely that its affect only depends upon the masses of the objects involved and the distance between them. Could it be that burning iron and steel somehow allows an allomancer to manipulate the gravity acting on a target object? The physical effects demonstrated by this ability seem to support this hypothesis, but closer examination reveals two small problems. 

The first is how such an effect would only work on metal. The second is that everything we know or currently theorize about the manipulation of gravity tells us that such a mechanism would not produce the magnitude of force necessary to explain the effects demonstrated by allomancers.


Electrodynamic Tethers

While there are likely things about gravity that we don’t fully understand, the most likely mechanism that I’ve found to explain these effects is that when pushing or pulling on metals, an allomancer creates a form of electrodynamic tether. From the University of Michigan:

“When a wire moves through a magnetic field, an electrical current results. As this current flows through the wire, it experiences a push from any external magnetic field – such as that found naturally around the Earth. The force exerted on the tether by the magnetic field can be used to raise or lower a satellite’s orbit, depending on the direction of the current’s flow.”

While the exact mechanism involved in allomantic pushing and pulling may differ from conventional electrodynamic tethers (if electrodynamic tethers can be thought of as conventional), the principles behind this technology seem to closely fit what we see in allomancy: a point to point connection between the allomancer and a conductive material. (Even the visual manifestation of this phenomenon, the thin blue line described earlier, seems to support this hypothesis).


Once again my usual caution applies regarding the avoidance of metal consumption. While some iron is of course essential for human health, large amounts can be harmful or fatal.

Read more Science of Allomancy:

Dr. Lee Falin is a Bioinformatician at the European Bioinformatics Institute, the host of the Everyday Einstein’s Quick and Dirty Tips podcast and the author of the “Science Fictioned” series, in which he takes scientific research articles and turns them into sciece fiction and fantasy short stories for middle grade and young adult readers. You can follow him on twitter at @qdteinstein.


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