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Geometric and physical interpretation of the action principle.

ABSTRACT: We give a geometric interpretation for the principle of stationary action in classical Lagrangian particle mechanics. In a nutshell, the difference of the action along a path and its variation effectively "counts" the possible evolutions that "go through" the area enclosed. If the path corresponds to a possible evolution, all neighbouring evolutions will be parallel, making them tangent to the area enclosed by the path and its variation, thus yielding a stationary action. This treatment gives a full physical account of the geometry of both Hamiltonian and Lagrangian mechanics which is founded on three assumptions: determinism and reversible evolution, independence of the degrees of freedom and equivalence between kinematics and dynamics. The logical equivalence between the three assumptions and the principle of stationary action leads to a much cleaner conceptual understanding.

SUBMITTER: Carcassi G

PROVIDER: S-EPMC10372048 | biostudies-literature | 2023 Jul

REPOSITORIES: biostudies-literature

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Geometric and physical interpretation of the action principle.

Carcassi Gabriele G Aidala Christine A CA

Scientific reports 20230726 1

We give a geometric interpretation for the principle of stationary action in classical Lagrangian particle mechanics. In a nutshell, the difference of the action along a path and its variation effectively "counts" the possible evolutions that "go through" the area enclosed. If the path corresponds to a possible evolution, all neighbouring evolutions will be parallel, making them tangent to the area enclosed by the path and its variation, thus yielding a stationary action. This treatment gives a ...[more]

PMID: 37495640

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Geometric and physical interpretation of the action principle.

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Geometric and physical interpretation of the action principle.

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