How can public spaces remain safe when large crowds move through them? Engineers and researchers who study these environments often rely on physical models borrowed from fluid dynamics—a branch of physics that describes the collective motion of fluids, whose behavior emerges from the interactions of many particles. But a new study published in the Journal of Statistical Physics: Theory and Experiment highlights a crucial issue: The way data are collected and measured within these models lacks standardization and may overlook important features of human collective behavior. Unlike particles, people are living agents with individual decisions and complex interactions, making their movement harder to capture with traditional approaches. ...read more read less