This post is primarily intended as an educational one, to discuss some of the terminology and thought-processes involved in materials science, but it was inspired by world-building considerations. As you may recall, if you’ve been following along with what I’ve been reading (and my regular book reviews), I recently read a book called The Substance of Civilization, which detailed how the materials to which our species has had access have shaped the course of cultural evolution over the past ten thousand years. It prompted me to think in more detail about choice of materials and construction techniques in world-building.
One of the choices I made early on in writing the first Fo’Fonas draft was to give the main character, Lomboc, a bronze sword. At the time, this was mostly supposed to be a repudiation of fantasy tropes. It seems sometimes that everyone in fantasy books runs around with steel weapons, yet steel did not become abundant and cheap until the development of the Bessemer Process in the nineteenth century. From what I understood at the time, steel weapons should have been rare and expensive during most of the comparable eras to those in which most fantasy stories take place. Various forms of iron would perhaps be viable, but steel? As late as the twelfth century BC, an iron dagger was still considered a kingly gift.
Reading The Substance of Civilization put that decision into a different light, and helped frame how that would affect other elements of the world-building process. Bronze is significantly softer than properly treated iron, and actually less abundant, but much easier to work. So would the Rezzixin Empire issue its soldiers with bronze weapons and armor, in a world that at least knows about iron and steel? It’s difficult to say, and I will need to undertake a more thorough examination of that decision as I go through revisions and a more formal world-building process (in my defense, Fo’Fonas did not start as an epic fantasy novel. It started as a random, single chapter to explain a magic system I had in my head).
What all of this discussion drives at is the importance of materials and their properties, and how much that connects to so much else in civilization, and in life. A given material’s properties are dictated by a huge number of factors, down to the molecular, atomic, and even subatomic scales, but having a basic understanding of the terminology involved is valuable, even if you’re not interested in studying the complexities of the chemistry and physics behind materials science. What do we even mean when we talk about the strength of a material?
There is no single way to measure strength, because the concept is more complicated than it initially appears. It is actually an amalgamation of two properties, and peak “strength” will depend on what you are using the material for, and a compromise between those two properties: hardness and toughness. In most cases, the harder a material is, the less tough it is, and the tougher a material is, the less hard it is. This tradeoff is often the dominant determining factor in choosing a material for a given undertaking (note that I am neglecting properties like conductivity, which are beyond the scope of what I want to discuss in this post – we’re just dealing with mechanics today).
Hardness is perhaps best expressed as the ability of a material to resist scratching. Glass, for instance, is very hard, as id diamond. It is very difficult to deform either of these materials. However, they are also very rigid: if you are able to deform them, they will likely shatter. Yes, even diamonds will shatter relatively easily if struck the wrong way (or the right way, depending on your goal, I suppose). Toughness, on the other hand, is a measure of a material’s ability to rebound from deformation. A rubber band, for instance, can be easily deformed hugely from its initial state, and still spring back to exactly how it was before. Yet it can be easily cut (lacking in hardness).
Steel is so useful because it provides a balance of both of these characteristics, making it strong. It may seem counterintuitive, but I would say that steel is stronger than diamond. Although it’s not as hard as diamond is – a diamond can easily scratch steel – it is much tougher, flexing and bending instead of cracking and shattered when exposed to stress. On the other side, steel cannot deform as much as rubber can without being permanently deformed, but it is much harder than rubber, which can be easily cut or sliced by a harder substance. When building a skyscraper, you want a material that isn’t going to shatter, but also one that isn’t going to get sliced in half if someone pinches it the wrong way.
Maybe this is all just the engineer in me making world-building far too technical. I often struggle with making my characters know or understand too much about their world in a scientific way. It is easy for me to come up with justifications for this in my head, but I fear that such instances represent glaring anachronisms in my works, which I am working to reduce. As much as it is an alternative world, and it needn’t (and shouldn’t) precisely follow the same path that our own civilization took, digressing too far strains the ideas of plausible impossibility. Could a culture that lacks significant ironworking technology really be developing vector field mathematics? Probably not (although there is some justification in the Fo’Fonas world, Sarctuar, for radically incongruous stages of technology and scientific development and understanding. The problem is that I don’t intend the reader to ever find out what that justification is).
Many of my stories, even my fantasy stories, are excuses for my to explore fairly scientific ideas – thinking about materials science in the context of world-building makes me want to incorporate a sword made of advanced ceramic materials into a story, somehow. Maybe you would rather keep your world-building a little less technical, but I really do think that having a basic understanding of some of the ways in which our environments shape our evolution allows us to craft more realistic, more interesting worlds. Knowledge of what happened in our past, and why, allows us to ask questions like “yes, but what if this other thing happened?” And to me, that’s a lot of what writing really is.