Light : Do We Even Know What It Is?

Whenever we look into the sky at night it seems that all the stars are laughing at us and showing us those amazingly beautiful places that we may never visit but how can we even see them all. Of course, you would answer that it is light due to which we can observe it.

But you need to think again. We humans, right from the beginning are playing a game called science. Whenever we notice something unusual we put on a story to explain how it works, in technical terms we give a theory to explain the phenomenon.

And then we together decide which story to keep and which to reject. Similarly “Light” is a story with help of which we define how we can see everything. But that’s a story we put on, then what is it? Well, great smart people tried to explain it, they also did, but not completely. If we go for a proper definition, light is the smallest form of energy- photon, an elementary particle- that can be transported without a real size. Now that is a quite heavy definition. In Layman's terms, it is something small which is traveling too fast.

We all are familiar with the wave-particle duality of light, we say its both wave and a particle. How do we know? , Because it acts as both a wave and a particle. When you put two torches such that their path of light coincide they just move without disturbing each other, well that’s what wave does when you throw two stones at different positions in a pond the wave produced by them will not collide they will move on even if they coincide. So that proves that it is a wave but the waves travel in a medium and the sunlight is traveling through space in the vacuum so how can it be a wave. So it must be a particle, we call the photon.

Well after years of thinking the dual nature of light as "both particle and a wave" has been proved, its essential theory was further evolved from electromagnetism into quantum mechanics. Einstein believed light is a particle (photon) and the flow of photons is a wave.

Now let's talk about its speed, we know it is the fastest thing, which can travel. The best story (reason) behind this is that the universe has set a limit of speed which we call “c” its value is 3 * 10^8 m/s. That means you are not able to travel faster than light. Now, why is that so? Well, we don’t know. Particles that have mass require energy to accelerate them. The closer to the speed of light you get a particle, the more energy is required to go faster. This is because the particles themselves get more massive in proportion to the increased velocity.

Earlier I told you it is the photon, which is traveling, but this gives birth to new questions, that what is the photon? How was it formed? It is the basic unit that makes up all light. The photon is sometimes referred to as a "quantum" of electromagnetic energy. Photons are not thought to be made up of smaller particles. They are a basic unit of nature called an elementary particle.

But we need to question ourselves again, once there was a time we thought atoms are the smallest indivisible particles but then we came to know there are further three divisions called the proton, neutron, and electron. Then we further divided into elementary particles. The Standard Model currently accounts for 6 quarks (up, down, strange, charm, bottom, top), 6 anti-quarks, 6 leptons (electron, muon and tau, and their respective neutrinos), 6 antileptons, 13 gauge bosons (8 gluons, photon, W+, W-, Z and graviton) and 1 Higgs boson. That adds up to 38 distinct elementary particles. So can there be more divisions of photons? We don't know but No, for now.

But we will never be able to observe smaller particles. That is because we could never see things smaller than photons. Why? Just think again how do you see things around you, by the light, which gets reflected, and what is light made of? Photons, so how could you reflect photons from something smaller than itself? So we cant divide photons further.

That’s why we call it indivisible. But still, there is much inside it unknown to us.

This light which is partially known to us is just an example, science is full of such examples, but that’s what we do. We shoot some stories to explain things and happenings around us.

Well, look around you; you will see a highly civilized world created by just a single species of animal, without light we could never have reached this far. We owe to light and the possibilities it has given us. So, after all, it’s not regret even if we don’t clearly understand what it is. But we have a pretty good idea of light, well, not perfect but good.