Max Planck did not want a revolution. He was a conservative, meticulous physicist who believed in the established laws of thermodynamics. But in 1900, while trying to solve a narrow technical problem about blackbody radiation, he stumbled on quantum theory — an idea so radical it unsettled him for the rest of his life, even as it demolished the foundations of classical physics.

This episode traces Planck’s reluctant quantum discovery and the personal tragedies that shadowed his scientific triumph — the death of his first wife, the execution of his son by the Nazis, and his agonizing decision to remain in Germany through the Third Reich.

• The blackbody radiation problem that forced Planck to break the rules of classical physics
• Why Planck himself resisted the full implications of quantum theory for years
• His complicated relationship with the Nazi regime and the cost of staying in Germany
• The execution of his son Erwin for the July 1944 plot against Hitler