The Ising model
The mathematical key to cracking “phase transitions” debuted exactly 100 years ago, and it has transformed the natural sciences. The Ising model, as it’s known, was initially proposed as a cartoon picture of magnets. It’s now so commonly used as a simple model of physical systems that physicists liken it to the fruit fly, biology’s model organism. A recently published textbook deemed the Ising model “the system that can be used to model virtually every interesting thermodynamic phenomenon.”
It has also penetrated far-flung disciplines well beyond physics, serving as a model of earthquakes, proteins, brains — and even racial segregation.
Charlie Wood — Quanta Magazine