Do you know what’s the most beautiful thing about Physics. It is that two of it’s greatest theories i.e; theory of relativity and quantum mechanics have their origins which are totally different from what they are actually about. For example, special theory of relativity which is about space and time has its root embedded in electrodynamics the four Maxwell’s equations similarly quantum mechanics was not born because we were asking questions what is matter made up of, we didn’t even know about nucleus.

In the year 1900, quantum mechanics was born because we were asking the question: what is light. Quantum Mechanics was formerly born when Max Planck gave his theory of light at the turn of 20th century. But the seeds of this theory were sown back in 17 century because of debate between Isaac Newton and Christian Huygens. To understand this debate let’s go back in time. In 17 century, we hardly knew about anything. There was no electrodynamics, no special relativity, no quantum physics and not even thermodynamics modern Physics was in its cradle Newton had just given his laws of motion and law of universal gravitation. Classical Physics was just born in 17th century. But what about light were we completely ignorant about it? The answer is no. There were few things that we knew about light. They were:

1. Light casts shadow and it travels in straight line.

2. Light is reflected of the surfaces.

3. Light refracts.

4. Light is composed of different colors.

What we didn’t Know about light is:

1. What is light made up of ?

In order to answer this question one of the greatest minds of 17th century, sir Isaac Newton gave his own theory of light. He said that light is made up of Particles which is called corpuscles. Newton could easily explain all above things with his particle model.

But Dutch physicist Christian Huygens Said that light is not made up of Particles light is wave, a disturbance in the medium just like sound waves, that disturbance travel in medium in form of light. He also proved all the know facts about light with his theory but not everything about light.

Both these models are right, as we know light is of dual nature. In 1801, the Young’s double slit experiment gave a fetal blow to Newton’s particle theory of light and all of the focus shifted to Huygens wave model.