Disclaimer: I’ve not formally studied string theory. All that I have explained is from novels and supplementary reading material. Please excuse me if I’m a bit vague.
Take any everyday object — say, a cup — and start cutting it. Keep breaking it into smaller and smaller pieces. Can you ever stop breaking it into pieces or will it go on forever? Well, forever(ish) — until you reach the very fundamental particles. But when you reach the very bottom of the pile — we can no longer see them. How do you exactly see anything? Suppose you want to look at your phone. Light strikes your phone, and then the light reflected from your phone strikes your eye and a mental image is created in your brain. But, the fundamental particles are so small that light — an electromagnetic wave — doesn’t strike them, and so, we can’t see them.
But scientists knew that they exist, so they pretended that the fundamental particle was a point in space (point = a point is a primitive notion that models an exact location in the space, and has no length, width, or thickness) space. Thus, the electron, which is a fundamental particle is considered a point with a certain mass and charge. Apparently, the charge and mass were calculated to an accuracy of about 0.0000000000002% (really). This was the birth of the Quantum Field theory and it has led to some very important discoveries in the real world.
But, like almost any other scientific theory, it comes with its flaws. In quantum Mechanics, all Forces are carried by certain particles. But, according to Einstein’s general relativity, gravity is not like any other force. In the fabric of spacetime, which is geometric, measurements must be precise. But, in the realm of quantum physics, this doesn’t happen. When Physicists tried to marry Gravity with the quantum field theory, the math broke down. If somehow scientists marry gravity with quantum field theory — we’d have the theory of everything.
Well, some really smart scientists came up with the string theory.
The String Theory gets rid of elementary particles and replaces them with pieces of vibrating strings. Like different vibrations of guitar strings create different sounds, different vibrations of strings create particles with different properties. And what’s more important is that this includes gravity as well. The world started hailing String Theory as the possible Theory of Everything. But then again, what scientific theory has no flaws? For string theory to be proven, we need at least 10 dimensions (and we have 4). Scientists have been trying to do the Math that makes string theory valid on earth, but it has not been proven yet.
So, String Theory might not be the theory of everything. But, it has the potential to help humanity progress in different ways as the quantum field theory did.
Thank you for taking the time to read.