© Left: German Federal Archive, Creative Commons Attribution ShareAlike 3.0 Germany License. Right: Francis Simon, courtesy AIP Emilio Segrè Visual Archives.

Werner Heisenberg (left) and Erwin Schrödinger (right) are two of the founding fathers of modern quantum mechanics. Schrödinger's formulation of a wave equation for particles, and his various solutions to it, gave rigorous answers to seeming paradoxes of quantum mechanics. Heisenberg developed an alternate formulation of quantum mechanics in terms of what was considered new math at the time: matrices and linear algebra. (Unit: 5)