steadystate

Steady state, sometimes written steadystate, is a condition in a system where macroscopic properties remain constant over time despite ongoing processes that would tend to change them. It reflects a dynamic balance maintained by continuous inputs and outputs rather than a static equilibrium.

In mathematics and physics, a steady-state solution is a fixed point or long-term behavior after transient effects have decayed. For linear time-invariant systems, the response becomes time-invariant; for periodically driven systems, the steady state is a periodic response that tracks the input phase and amplitude.

In chemistry and biochemistry, steady state describes a situation in which the rate of production of a species equals its rate of removal, so its concentration remains constant. This assumption underpins metabolic flux analysis and kinetic modeling. It is distinct from thermodynamic equilibrium, where all net flux ceases and the system reaches minimum free energy.

In electronics, steady state refers to voltages and currents that have settled to constant or periodic values after switching on, with transient components dissipated.

In ecology and economics, steady state denotes a condition where population, capital stock, or other state variables remain constant over time when inflows balance losses. In economics, this concept is related to balanced growth paths or stationary economies.

A non-equilibrium steady state occurs when a system maintains constant macroscopic properties while continuously exchanging energy or matter with its surroundings, driven by external input. Distinctions from true equilibrium are important for understanding real-world, dissipative systems.