👉 A Courant-Einstein equation is a type of partial differential equation that arises in the theory of elasticity. It is named after French mathematician Henri Poincaré and Italian physicist Enrico Fermi, who independently discovered it. The equation describes how the stress tensor affects the motion of a material under its own internal forces.
The equation can be written as:
∇²u = α
σ(u)
where u(x,t) is a function describing the displacement at position x in time t and