whatA polycrystal drawn as its boundaries alone: every cell of the lattice belongs to a grain, energy is nothing but the count of unlike neighbours, and a cool Metropolis anneal lets each boundary drift by its own curvature. Metal under the microscope, in ink.

whyThe claim is coarsening's three-part law, each part measured. The network coarsens relentlessly: the grain count falls and the mean area multiplies. The small are eaten first: an id-survival ledger tracks every starting grain, and the smallest half dies far faster than the largest half. And the junctions obey Plateau: where three boundaries meet, an angle census (arms sampled around each vertex) pulls toward 120 degrees as the anneal proceeds. Click anywhere to pin a disk of material -- a quenched region that keeps its fine grains while the world around it grows coarse.

howA Potts model at temperature 0.45: random sites propose adopting a neighbour's grain id, downhill moves always accepted, uphill by Boltzmann's coin. Grains begin as a seeded periodic Voronoi of 140 sites. The census samples 2x2 vertices holding exactly three grains; arm directions are averaged over the pair-boundaries within seven cells -- a declared approximation on a lattice. Pinned cells never flip.