Part 3/11:
Planck’s work on the so-called "black body radiation" unveiled a strange phenomenon—an "ultraviolet catastrophe." As scientists invested time understanding the rays emitted by heated filaments, the connection between light and energy baffled them. Meanwhile, experiments related to the photoelectric effect raised more questions than answers. The puzzling behavior of light forced physicists to consider that light might not merely be a wave, as traditionally thought, but could also behave like particles, dubbed "quanta."