This year, Nature celebrates its 150th birthday. To mark this anniversary we’re rebroadcasting episodes from our PastCast series, highlighting key moments in the history of science.In this episode, we’re heading back to the early twentieth century, when physicists had become deeply entangled in the implications of the quantum theory. At its smallest scales was the world continuous? Or built of discrete units? It all began with Max Planck. His Nobel Prize was the subject of a Nature news article in 1920.This episode was first broadcast in December 2013.From the archiveNature 16 December 1920 For information regarding your data privacy, visit acast.com/privacy