The story of Heisenberg's quantum mechanics

Ninety years ago the birth of quantum mechanics took place when Werner Heisenberg submitted his paper on “Quantum-theoretical reinterpretation of kinematic and mechanical relations“ (Über quantentheoretische Umdeutung kinematischer und mechanischer Beziehungen) to Zeitschrift für Physik. [Z. Phys., 33, 879-893 (1925)]. We will show how important the historical context was for an understanding of his work and we will follow Heisenberg on the narrow path that took him from the unsuccessful old quantum mechanics to the light of the new quantum mechanics. We then discuss Heisenberg’s research in the years following his scientific breakthrough.