eli5 What is light made up of? Where does it come from inside a torch? Is light just un-containable luminous particles than can never be studied as a single unit inside a Microscope?
In: Physics
We don’t really know what light “is”. We have just been able to observe and determine certain characteristics about how it behaves. Light has no mass, but it has momentum. It can act both as a discrete particle and as a wave. It doesn’t require a medium to travel through, which is how it travels through space. The base unit of light is called a photon. This is a single particle-like unit of light (although it simultaneously acts like a wave).
It is the same with all matter/particles. We know that protons and neutrons are made up of 3 smaller particles called quarks, but we don’t know what a quark really “is”. Its called a fundamental particle because at this point, as far as we can tell, it is the base “stuff” that makes a proton or neutron. We haven’t been able to break a quark into anything smaller. We know there is a relationship between it and energy (most famously with the equation E = MC^2). Electrons are another fundamental particle. We haven’t been able to break an electron into any smaller.
Effectively, a photon is a photon because it is made of nothing but photon, an electron is an electron because it is made of an electron, and quarks are quarks becuase they are made of a quark.
Light can be generated in many ways. One common way is when electrons drop from a higher energy to a lower energy. Energy cannot be destroyed, so it has to go somewhere. In this case it is emmited in the form of a “photon” or light. This photon will have the exact amount of energy that was lost when the electron changed energy levels.
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