To understand what is quantum physics, we need to go more than 100 years back in time. We had pretty much figured out how the world works. We could explain the motion of objects around us, the waves on strings, the ripples in the pond and even the motion of the planets around thesun. But when we think we know everything, nature throws us problems. There were three major events that gave birth to quantum mechanics.
The first was in 1900 when a group of bulb manufacturers approached Max Planck. They wanted to make their bulbs more efficient. This requireda better understanding of the famous black body curve. Planck was confused on how to solve this problem. After a lot of brainstorming, he came up with an assumption: He said energy in the form of light can only be emitted in discrete amounts. It cannot be emitted continuously.
1.4 units, 3.5 units, 6.2 etc were not allowed. Planck did not realise the importance of this hypothesis.
5 years later, Albert Einstein who back then was a struggling third class patent clerk in Switzerland realized the importance of Plack’s workand used it to explain the photoelectric effect. This was the second blow to classical mechanics.
The third and the final nail in the coffin of classical physics came from Niels Bohr. When we pass electric current through gas to ionize it, and observe it through a spectrometer, we see very fine spectral lines. Their origin could not be explained by the existing theories. Bohr attributedthese lines to the jumps made by electrons from one level to another. Bohr’s theory was the first leap to explain the structure of the atom.
Credit The secrets of Universe