According to Jim Rutt, 'phase change' refers to a critical transformation within complex systems, both in natural and artificial domains, where the system transitions from one state or phase to another, leading to the emergence of new properties and behaviors. This concept is deeply rooted in physics, where it describes phenomena like ice melting into water, but Jim expands the definition to include broader applications such as shifts in market dynamics, sociopolitical structures, or technological adoption cycles. Phase changes are often catalyzed by specific thresholds or tipping points, beyond which small changes can lead to disproportionately large impacts. By understanding phase changes, one can better predict, manage, and leverage these pivotal shifts to navigate the complexity of evolving systems.

See also: phase transition, emergence, agent-based modeling, evolutionary computing, evolutionary psychology