#OTD in 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.
This is the first of two theorems (see Noether's second theorem) proven by mathematician Emmy Noether in 1915 and published in 1918.
https://en.wikipedia.org/wiki/Noether%27s_theorem
Noether's second theorem:
https://en.wikipedia.org/wiki/Noether%27s_second_theorem