# List of types of equilibrium

This is a list of various types of equilibrium, the condition of a system in which all competing influences are balanced.

## Biology

* Equilibrioception, the sense of a balance present in human beings and animals
* Equilibrium unfolding, the process of unfolding a protein or RNA molecule by gradually changing its environment
* Genetic equilibrium, theoretical state in which a population is not evolving
* Homeostasis, the ability of an open system, especially living organisms, to regulate its internal environment
* Punctuated equilibrium, theory in evolutionary biology
* Sedimentation equilibrium, analytical ultracentrifugation method for measuring protein molecular masses in solution
* Equilibrium Theory (Island biogeography), MacArthur-Wilson theory explaining biodiversity character of ecological islands
* Osmotic equilibrium, balance between solvent flow and pressure across a membrane

## Physics

* Equilibrant force, which keeps any object motionless and acts on virtually every object in the world that is not moving
* Equilibrium figures of Earth and planets (physical geodesy)
* Equilibrium mode distribution, the state of fiber optic or waveguide transmission in which the propagation mode does not vary with distance along the fiber or changes in the launch mode
* Hydrostatic equilibrium, the state of a system in which compression due to gravity is balanced by a pressure gradient force
* Hyperbolic equilibrium point, a mathematical concept in physics
* Mechanical equilibrium, the state in which the sum of the forces, and torque, on each particle of the system is zero
* Radiative equilibrium, the state where the energy radiated is balanced by the energy absorbed
* Secular equilibrium, a state of radioactive elements in which the production rate of a daughter nucleus is balanced by its own decay rate
* Thermodynamic equilibrium, the state of a thermodynamic system in which there are no net flows of matter or energy
* Isostatic equilibrium, in geology, the balance between gravitation and buoyancy of the Earth's crust in the mantle

## Chemistry

* Chemical equilibrium, the state in which the concentrations of the reactants and products have stopped changing in time
* Diffusive equilibrium, when the concentrations of each type of particle have stopped changing
* Thermal equilibrium, a state where an object and its surroundings cease to exchange energy in the form of heat, i.e. they are at the same temperature
* Donnan equilibrium, the distribution of ion species between two ionic solutions separated by a semipermeable membrane or boundary
* Dynamic equilibrium, the state in which two reversible processes occur at the same rate
* Equilibrium constant, a quantity characterizing a chemical equilibrium in a chemical reaction
* Partition equilibrium, a type of chromatography that is typically used in GC
* Quasistatic equilibrium, the quasi-balanced state of a thermodynamic system near to equilibrium in some sense or degree
* Schlenk equilibrium, a chemical equilibrium named after its discoverer Wilhelm Schlenk taking place in solutions of Grignard reagents
* Solubility equilibrium, any chemical equilibrium between solid and dissolved states of a compound at saturation
* Vapor–liquid equilibrium, where the rates of condensation and vapourization of a material are equal

## Economics

* Competitive equilibrium, economic equilibrium when all buyers and sellers are small relative to the market
* Economic equilibrium, a condition in economics
* Equilibrium price, the price at which quantity supplied equals quantity demanded
* General equilibrium theory, a branch of theoretical microeconomics that studies multiple individual markets
* Intertemporal equilibrium, an equilibrium concept over time
* Lindahl equilibrium, a method proposed by Erik Lindahl for financing public goods
* Partial equilibrium, the equilibrium price and quantity which come from the cross of supply and demand in a competitive market
* Radner equilibrium, an economic concept defined by economist Roy Radner in the context of general equilibrium
* Recursive competitive equilibrium, an economic equilibrium concept associated with a dynamic program
* Static equilibrium (economics), the intersection of supply and demand in any market
* Sunspot equilibrium, an economic equilibrium in which non-fundamental factors affect prices or quantities
* Underemployment equilibrium, a situation in Keynesian economics with a persistent shortfall relative to full employment and potential output
* Dynamic stochastic general equilibrium, an econometric method that applies general equilibrium theory and microeconomic principles.

## Game theory

* Correlated equilibrium, a solution concept in game theory that is more general than Nash equilibrium
* Nash equilibrium, the basic solution concept in game theory
** Quasi-perfect equilibrium, a refinement of Nash Equilibrium for extensive form games due to Eric van Damme
** Sequential equilibrium, a refinement of Nash Equilibrium for games of incomplete information due to David M. Kreps and Robert Wilson
** Perfect Bayesian equilibrium, a refinement of Nash equilibrium for games of incomplete information that is simpler to use than sequential equilibrium
* Symmetric equilibrium, an equilibrium where all players use the same strategy
* Trembling hand perfect equilibrium assumes that the players, through a "slip of the hand" or tremble, may choose unintended strategies
** Proper equilibrium due to Roger B. Myerson, where costly trembles are made with smaller probabilities

## Other

* Social equilibrium, a system in which there is a dynamic working balance among its interdependent parts
* Equilibrium moisture content, the moisture content at which the wood is neither gaining nor losing moisture
* Equilibrium point, in mathematics, a constant solution to a differential equation
* Reflective equilibrium, the state of balance or coherence among a set of beliefs arrived at by a process of deliberative mutual adjustment
* Comfortable equilibrium, or the Clarinda Equilibrium refers to the psychological state of mental harmony and equanimity with the frequently opposing stresses and strains of complicated circumstances in tension. As situations unfold, there will be the tendency for the equilibrium to shift and adjust, yet for these different stable equilibria transient or otherwise, there is an intrinsic zone of equanimity of psychological disposition that marks out a psychological resilience that transcends any such uncomfortable shifts.