Simple universal models capture all classical spin physics

Abstract

One model to rule them all? The idea of finding an all-encompassing model to describe the world around us has appealed to generations of scientists. Although we are very far from this ultimate goal, more modest steps can be taken if we focus on particular problems. De las Cuevas and Cubitt used concepts borrowed from computer science to show that all classical spin models (introduced initially to study magnetism) can be solved by tackling a slightly more complex, universal model (see the Perspective by Wehner). Thanks to these findings, it may be possible to physically simulate systems with complex interactions, using the well-understood two-dimensional Ising model with fields. Science , this issue p. 1180 ; see also p. 1156