5 December – Today in German History


  • Birth of Wernher Heisenberg (1901-1976) in Würzburg, Germany. He was a theoretical physicist who was awarded the Nobel Prize for Physics in 1932 for the creation of quantum mechanics. His 1925 theory of quantum mechanics offered a matrix method to explain stationary discrete energy states and was soon superseded by Erwin Schrödinger’s more intuitive wave equation. Of more lasting impact was his 1927 uncertainty principle, which states that it is impossible to accurately measure both position and momentum (energy and time) concurrently and that the more precisely we know an object’s position, the less precisely we can know its momentum, and vice versa. During World War II he led Germany’s failed efforts to develop an atomic bomb, though his group never came close to achieving this goal and Heisenberg himself doubted it was possible. His other areas of research included cosmic rays, ferromagnetism, the hydrodynamics of turbulent flows, and subatomic particles.


  • During World War II, Allied troops took Ravenna, Italy.