Every cell is a spin, +1 (an edge) or −1 (a vector). A random spin flips if that lowers the energy E = −Σ sisj; otherwise it flips with probability e−ΔE/T.
Drag T across Tc ≈ 2.269. Tap to paint a +1 disc. The same ?seed= always gives the same run.
LITThe 2D Ising model with Metropolis dynamics. Onsager’s Tc = 2/ln(1+√2) ≈ 2.269. Every 30 steps the tracked energy must equal the energy recomputed from scratch, or the page throws.
AMBERReading +1/−1 as edges and vectors is the site’s language.