principle of least action

E145354

The principle of least action is a fundamental concept in physics stating that the path taken by a physical system between two states is the one for which a specific quantity called the action is minimized (or made stationary), forming the basis of Lagrangian and Hamiltonian mechanics.

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Predicate Object
instanceOf concept in theoretical physics
physical principle
variational principle
actionDefinedAs time integral of the Lagrangian
allows derivation of Euler–Lagrange equations
appliesTo classical field theories
conservative systems
electromagnetic field
gravitational field
nonrelativistic mechanics
relativistic mechanics
associatedWithScientist Carl Gustav Jacob Jacobi
surface form: Carl Gustav Jacobi

Joseph-Louis Lagrange
Leonhard Euler
Pierre-Louis Moreau de Maupertuis
surface form: Pierre Louis Maupertuis

Richard Feynman
William Rowan Hamilton
basedOn action functional
canYield maxima of action
minima of action
saddle points of action
conceptualFeature global description of motion between boundary conditions
coreConceptOf Hamiltonian mechanics
Lagrangian mechanics
path integral formulation of quantum mechanics
defines dynamical evolution of physical systems
equivalentTo Newton's laws for many mechanical systems
field classical mechanics
field theory
general relativity
quantum mechanics
generalizes Newtonian mechanics
historicalPrecursor Fermat's principle of least time
implies conservation laws via Noether's theorem
mathematicalFormulationUses calculus of variations
modernInterpretation compact mathematical encoding of dynamics
oftenMisstatedAs physical trajectory minimizes the action
philosophicalAspect teleological interpretations historically discussed
relatedConcept principle of least action self-linksurface differs
surface form: Hamilton's principle

stationary action principle
relatedQuantity Hamiltonian
requires boundary conditions at initial and final times
statedAs physical trajectory makes the action stationary
usedFor deriving Einstein field equations in general relativity
deriving Maxwell's equations
deriving equations of motion
formulating gauge theories
formulating relativistic particle dynamics
usesQuantity Lagrangian
variationCondition first variation of action vanishes on true path

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Referenced by (5)

Full triples — surface form annotated when it differs from this entity's canonical label.

Pierre-Louis Moreau de Maupertuis knownFor principle of least action
Euler–Lagrange equation relatedTo principle of least action
this entity surface form: Hamilton’s principle
William Rowan Hamilton knownFor principle of least action
this entity surface form: Hamilton's principle
principle of least action relatedConcept principle of least action self-linksurface differs
this entity surface form: Hamilton's principle
d’Alembert’s principle relatedTo principle of least action
this entity surface form: Hamilton’s principle