26 July 1918 – Emmy Noether’s paper, which became known as Noether’s theorem was presented at Göttingen, Germany, from which conservation laws are deduced for symmetries of angular momentum, linear momentum, and energy.
26 July 1918 – Emmy Noether’s paper, which became known as Noether’s theorem was presented at Göttingen, Germany, from which conservation laws are deduced for symmetries of angular momentum, linear momentum, and energy.
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Noether’s theorem or Noether’s first theorem states that every differentiable symmetry of the action of a physical system with conservative forces has a corresponding conservation law.
The theorem was proven by mathematician Emmy Noether in 1915 and published in July 1918.
The action of a physical system is the integral over time of a Lagrangian function, from which the system’s behavior can be determined by the principle of least action.
This theorem only applies to continuous and smooth symmetries over physical space.
[Noether’s theorem](https://math.ucr.edu/home/baez/noether.html) is an amazing result which lets physicists get conserved quantities from symmetries of the laws of nature.
Time translation symmetry gives conservation of energy; space translation symmetry gives conservation of momentum; rotation symmetry gives conservation of angular momentum, and so on.
This result, proved in 1915 by Emmy Noether shortly after she first arrived in Göttingen, was praised by Einstein as a piece of “penetrating mathematical thinking”. It’s now a standard workhorse in theoretical physics.
Very beautiful work.