7.1.1 History of Quantum Physics

Classical theory:
1. Newtonian physics
2. Classical mechanics is based on Newton’s laws of motion. Isaac Newton described light as a single stream of particles.
3. Properties of light are explained by Maxwell’s electromagnetic wave theory.
4. Interference pattern observed in double-slit experiment conducted by Thomas Young confirmed light as a wave.
5. John Dalton introduced the atomic model while J.J. Thomson suggested the existence of electrons in the atomic model.
6. Two physical models to represent energy in motion: particle model and wave model.
Quantum theory:
1. Discusses the microscopic physical processes
2. Max Planck introduced the concept of quantum which led Albert Einstein to determine that light exists in discrete quanta of energy or photons.
3. Niels Bohr explained that the emission spectrum of hydrogen is due to the transition of electrons between different energy levels.
4. Louis de Broglie described the wave-particle duality of light and subatomic particles.