Emmy Noether and Her Theorems

Today Noether's principal theorem occupies a prominent place in theoretical physics, though for a long time its significance was largely overlooked. Even now, relatively few physicists realize that Emmy Noether's original paper from 1918 contains two fundamental theorems. Moreover, both theorems are essential for understanding her original motivation, namely to distinguish between proper and improper conservation laws in physics. Readers familiar with Noether's Theorem, relating group symmetries to conserved quantities, may well wonder why the plural form in the title. The reason: her famous paper from 1918 contains not one, but two fundamental theorems. The first relates to special relativity, whereas the second pertains to Einstein's general theory based on the principle of general covariance.image