hey there!  welcome to the new episode of Curiosity! A series in which we will answer some of the questions that makes us all curious.   

Light helps in connecting us (humans) to the universe.  You may have heard of "electromagnetic waves"  or light is made of Photons. But have you ever thought what does that really mean? What actually is light? Well that's what we are gonna discuss today. SO, lets get started.

Firstly, How light came into Existence?

There are many theories of how the light came into existence but here's the most accepted one.  Immediately after Big bang the Electromagnetic force didn't come into existence. It was binded with the weak nuclear forces. The particles like B and W bosons existed at that time. When early Universe was just   few nano seconds old it cooled down immediately. This cool down was enough for electromagnetism to break free from weak nuclear forces. Also B and W bosons started combining to form photons. This newly formed photos mixed together with quarks. They are basically smallest building blocks of matter. 

Fig : Big bang (Credits)

When Universe was just  0.00001 seconds old, the new formed quarks combined to form proton and neutrons. When the universe was 0.01 seconds old the atoms started forming. 

After thousands of year, the Photons broke free and streamed across the Universe , but the formed light is supposed to be very dim and red because there was no source of light like stars.

Finally after millions of years, the formation of stars kicked the nuclear reactions, generating new light and streaming across the universe. Similarly, our sun formed 4.6 billion years ago and showered our solar system with new photons.

So,What actually is Light?

In simple terms, Light is the smallest form of energy that is transmitted. Made up of Photons.  Photons are basically the elementary particles. They don't have any real size. Photons can't be split, they can only be created and destroyed.Also Light shows wave- particle nature. This means light can be both wave and a particle at the same time.

When we talk about light, we are actually taking about VISIBLE light. It's just a very tiny part of Electromagnetic spectrum.

Fig : Visible Light in the Electromagnetic Spectrum (Credits)

Different forms of radiation in Electromagnetic spectrum have got very different wavelength and frequencies. Gamma rays have smallest wavelengths. Gamma rays have got wave length of some picometer , which is even smaller than the hydrogen atom. Our Visible light is in the range of 400 nano meters to 700 nano meters. Also the wavelength of the radio and Broadcast signals can be way more than a kilometer.

But all these radiations have same wave-particle duality nature and all of them travel at speed of light.

Why can we only see Visible Light Then?

Why is Visible light so important for humans, there are so many other forms of waves, we can't see them, why only visible light? well the answer is, visible light is nothing special. We humans just evolved our eyes to see the visible light. 

Visible light is the only part of electromagnetic spectrum that refracts in water. This led to evolving of first eyes millions of years ago in the vast oceans of Earth. 

How is light formed?

Fig: Emission of Energy (Credits)

Electromagnetic waves are created when there's atoms drops from higher state to lower state of energy. The energy is lost and emitted in the form of radiation. Similarly visible light is microscopically created when the electron drops down from the higher energy state to the lower energy state. The moving charge of an electron creates a oscillating magnetic field which in turn creates a oscillating electric field perpendicular to it. This two two fields move together through through space.

Conclusion

Light is basically the form of energy (visible light) that is made of photons showing both wave and particle nature. Our eyes co-indecently developed or evolved to see the visible light which is a very short part of electromagnetic spectrum. There would be absolutely no meaning of light ,if there were no living things with evolved eyes to observe it.

  That's it for this Episode guys, Hope you enjoyed it. If you did, Upvote and comment your thoughts below. Thank you

Stay Curious.

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Last Five Episodes:

 Curiosity | How did life Begin On Earth?

Curiosity | What Happens when you go into Coma? 

Curiosity | Why do some people Sleep Walk? 

Curiosity | What is the possibility of being hit by an Asteroid? 

 Curiosity #36 | Can Freezing our body make us Immortal?