Showing posts with label simmetria. Show all posts
Showing posts with label simmetria. Show all posts

Friday 29 April 2011

Noether's (first) theorem

"Noether's (first) theorem states that any differentiable symmetry of the action of a physical system has a corresponding conservation law. The theorem was proved by German mathematician Emmy Noether in 1915 and published in 1918.[1] The action of a physical system is the integral over time of a Lagrangian function (which may or may not be an integral over space of a Lagrangian density function), from which the system's behavior can be determined by the principle of least action.
Noether's theorem has become a fundamental tool of modern theoretical physics and the calculus of variations. A generalization of the seminal formulations on constants of motion in Lagrangian and Hamiltonian mechanics (1788 and 1833, respectively), it does not apply to systems that cannot be modeled with a Lagrangian; for example,dissipative systems with continuous symmetries need not have a corresponding conservation law." Wikipedia, l'enciclopedia libera.

Spherical symmetry

Everything is the same in all directions (as if on the surface of a sphere).


Da un libro sulle simmetrie