What is the free energy principle?

The Free Energy Principle is a concept formulated by Karl Friston that describes how systems survive and interact with their environment by minimizing variational free energy. This principle is fundamentally about understanding existence as an inference problem, where survival and interaction of a system in a changing environment can be modeled statistically.

This principle is deeply rooted in fields such as machine learning and statistical analysis. In essence, it proposes that all systems that exist, strive to minimize their free energy. This includes living systems which, by this definition, are constantly engaging in processes that attempt to minimize free energy or, in other words, maximize the likelihood of their continued existence in their environment.

Variational free energy here is essentially a measure of surprise; by minimizing this surprise, systems (ranging from individual neurons to entire organisms) maintain a homeostatic state that is crucial for survival. This makes free energy a valuable metric for understanding various phenomena across biological and artificial systems, such as brain functioning and artificial intelligence modeling 1 2.