Évacuons

Évacuons is a fictional concept used in discussions of evacuation modeling to denote discrete, instantaneous removal events from a system of agents. It serves as a modeling abstraction rather than a physical object.

The name combines the French verb évacuer with the -on suffix often used for elementary particles, signaling a unit-like element connected to evacuation dynamics.

In theoretical crowd models, évacuons are treated as quasi-particles that can be produced near exits when local density or hazard signals exceed a threshold. Each évacuon represents a single person effectively removed from local density, thereby reducing crowding and altering flow rates. They are defined to carry no energy or momentum; their purpose is to track impulsive reductions in population rather than to describe a new physical carrier.

Production rates depend on factors such as density, observed risk, exit capacity, and the state of the building. Annihilation occurs when the corresponding evacuation event finishes at an outlet, or when the system transitions to a lower-density configuration.

Applications and limitations: Évacuons are used in thought experiments and simulations to explore the impact of abrupt exodus on bottlenecks and evacuation efficiency. The concept is not empirically observed, and models employing évacuons must be interpreted as abstractions rather than descriptions of fundamental physics.

See also: crowd dynamics, evacuation modeling, simulation, conservation laws.