What can springs can teach us about solids?
You might think of solids as fixed objects with atoms fixed in place. However, atoms in solids keep bouncing off each other in the same way as in a gas. The main difference is that in a solid, atoms don’t move relative to their neighbors. They maintain a fixed pattern like the hexagonal structure (each atom has 6 neighbors) in the animation and this is essential for the key properties that distinguish solids from other phases of matter.
Why do atoms in solids like to stick together unlike gases?
At this scale, atoms experience two kinds of relevant energies. One is thermal energy, the other is energy due to electrical interactions between atoms. This is quite an oversimplification of the interactions at the atomic scale. There are other energy contributions due to electron numbers, magnetic fields arising from motions of charges within atoms, nuclear energies, etc. A complete understanding of these contributions on material properties lies in quantum mechanics. And don’t get me wrong, they are important. Properties like what color a material is and how well it can conduct electricity depend on these interactions. However, for the purpose of this discussion: why do atoms in a solid stick together, we can ignore the complex interactions for now. Maybe in a later blog I’ll discuss other types of interactions…
