Towards the end of the 19th century, scientists discovered phenomena in both the macro and micro worlds that classical physics could not explain.
Notes on verification
Multiple authoritative academic sources including university educational materials and peer-reviewed arxiv papers confirm both the micro-world phenomena (blackbody radiation, photoelectric effect, ultraviolet catastrophe) and macro-world phenomena (Mercury's perihelion precession anomaly). The specific examples, dates, and measurements are consistently corroborated across independent sources.
Sources
- Introduction to quantum mechanics (wikipedia)