Noether's second theorem

In mathematics, Noether's second theorem relates symmetries of an action functional with a system of differential equations. The action S of a physical system is an integral of a so-called Lagrangian function L, from which the system's behavior can be determined by the principle of least action.

Specifically, the theorem says that if the action has an infinite-dimensional Lie algebra of infinitesimal symmetries parameterized linearly by k arbitrary functions and their derivatives up to order m, then the functional derivatives of L satisfy a system of k differential equations.

Noether's second theorem is sometimes used in gauge theory. Gauge theories are the basic elements of all modern field theories of physics, such as the prevailing Standard Model.

See also

• Noether's first theorem
• Noether identities
• Gauge symmetry (mathematics)
• Emmy Noether

External links

• English translation of Noether's paper
• Fulp, R., Lada, T., Stasheff, J.. Noether variational theorem II and the BV formalism, arXiv: math/0204079
• Bashkirov, D., Giachetta, G., Mangiarotti, L., Sardanashvily, G., The KT-BRST complex of a degenerate Lagrangian system, Lett. Math. Phys. 83 (2008) 237; arXiv: math-ph/0702097.