Figure 2.

Frustration entered the physics lexicon in the study of magnets. The arrows represent spins that can be in any two states: up or down. Favorable antiferromagnetic interactions between spins are represented by squiggly lines. The potentially frustrating problem is: what is the lowest energy arrangement of the up and down spins that can be reached dynamically? On the left, the particles are arranged on a rectangular lattice. How would you set the spins such that all local interactions are satisfied? What happens if the particles are arranged on a triangular lattice, as shown on the right? There is no way to arrange the spins so that every component interaction can be minimized. The triangle is “frustrated”