Four Fundamental Forces
In Physics, there exists four fundamental fources (get it? 4ces?). These forces are Gravity, Electromagnetism, Strong Nuclear Force, and Weak Nuclear Force. These four forces are responsible for everything in our universe- though we've yet to explain how they all work in tandem. That concept will be explored later though, because for now, let's dive more in depth into these four forces.
You may understand it as the force that keeps us grounded on earth, and it is exactly that. Gravity is the force, or rather, the attraction between physical bodies that have mass. This was the first force to be discovered.
As the name implies, electromagnetism encompasses both the fields of electricity and magnetism. This force deals with electrical and magnetic fields, and how they interact with each other and the masses involved. Electromagnetism was the second fundamental force discovered.
This force is- so to speak- the super glue between the particles in an atom. It is what keeps the neutrons and protons of an atom stuck together, and tinkering with this force has led to the creation of atomic bombs. Of all the forces, this one is the most powerful.
Last but not least is weak nuclear force. It turns neutrons into proton, and is responsible for what we know as particle decay.
So now that we know about these concepts, what do we do with them?
You see, a question that has been plaguing scientists for ages is combining all these pieces of the puzzle into one rule- one law- that can explain our universe. This goal is called 'Unification'. If we can figure out how all these elements work in tandem, them we will know how the universe works.
It's harder than it seems though. This is because the concept of gravity, and the concepts of electromagnetism and the nuclear forces, though on their own are explainable through mathematics, are near impossible to combine into a single equation. Though many years have passed since the problem first arose, humanity still has not found a solution to the great question of unification.
That being said, it's not like humanity has made no progress.
Though yet to be proven by science, a popular theory that could unify the four forces is known as string theory. The scientific community is split on their view of it. Some find it a waste of time and talent, while others find that it's a promising solution to the question of unification.
Either way, string theory proposes that everything in the universe, from stars to you are, at their base, composed of tiny tiny vibrating strands of energy called strings. These strings vibrate at different frequencies, and supposedly make up the universe. Though much math has been done to prove that this theory may be correct, these strings are so tiny that they cannot actually be experimented on- and a principal of fact is that it must be able to be tested to be true. Its inability to be tested is what makes this theory fall short, and what stops it from turning into a truth. It has yet to be disproven, and has yet to be proven.