Did Max Planck think that light was a wave or a particle?
“Einstein’s hypothesis of light quanta (photons), based on Philipp Lenard’s 1902 discovery of the photoelectric effect, was initially rejected by Planck. He was unwilling to discard completely Maxwell’s theory of electrodynamics. “The theory of light would be thrown back not by decades, but by centuries, into the age when Christian Huygens dared to fight against the mighty emission theory of Isaac Newton …” In 1910 Einstein pointed out the anomalous behavior of specific heat at low temperatures as another example of a phenomenon which defies explanation by classical physics. Planck and Nernst, seeking to clarify the increasing number of contradictions, organized the First Solvay Conference (Brussels 1911). At this meeting Einstein was able to convince Planck. Meanwhile Planck had been appointed dean of Berlin University, whereby it was possible for him to call Einstein to Berlin and establish a new professorship for him (1914).
