This is the second video of the series 'Introduction To Quantum Mechanics'.
In the first video, we talked about what is quantum mechanics and how is it different from classical and statistical mechanics. Quantum mechanics formally began in the year 1900, when German Physicist Max Planck explained the black body spectrum.
But the seeds of this theory were sown back in the 17th century because of a debate between Sir Isaac Newton and Christiaan Huygens.
Quantum mechanics was not born because we were asking the question of what is matter made up of? It was born because we were asking the question: What is light? In the 17th century, we hardly knew anything. There was no electrodynamics, no relativity, and not even thermodynamics. Classical physics was in its cradle. We knew some things about light:
1. Light travels in a straight line and it casts shadows.
2. Light reflects
3. Light refracts
4. Light is made up of different colors.
But what we didn't know was what is light made up of. According to Newton, light is composed of particles, which he called corpuscles. Using his corpuscular theory of light, Newton easily explained all the known facts about light.
But Dutch Physicist Christiaan Huygens said that light is a wave, a disturbance in the medium. Even Huygens could explain everything using his theory of light. But back then, Newton had a higher status among the physicists and hence his theory was preferred. Later, in 1801, Young's double-slit experiment showed that light is made of waves. So by the beginning of the 19th century, Huygens' wave model had full control.