We all are curious in one way or the other in understanding the mysteries of the universe. All have different curiosities from feeling the beauty of the universe, getting intrigued by the complexity of it to loving the elegance of it. Let us try to understand the same in simple terms.
If we need to understand something, we need to go to the base level of it and come up by understanding all the necessary information. For example, to understand and read a sentence in any language, we need to learn the alphabets, their sounds, punctuations so and so forth.
In the realm of science, the branch that deals with matter, its motion and behaviour through space and time is “physics.” The main goal of physics is to understand how the universe works. So, we will take help of physics and come up from the base level to understand the universe.
Everything around us consists of “matter”, and the definition of matter is anything that occupies space and has mass. From small sand grain to a complex structured human being everything is made of matter. Matter consists of tiny particles called “atoms”. As we all know, atoms have protons, neutrons, electrons and unstable nucleus.
It is the definition of “Subatomic particles” or “elemantary particles.” These are the basic building blocks of atoms and in turn, building blocks of everything. The particles are so small that light passes through them. For something to be visible to an eye, the light must touch them and reflect on our eye.
We can decrease the wavelength of the light and try to see these particles. However, as per the wave theory, when the wavelength decreases, the energy of the wave increases. So when the more energy wave touches these particles, it alters them. So we cant measure them precisely.
This fact or phenomenon is called “Heisenberg’s uncertainty principle” this is bases of all “Quantum Physics.” In rudimentary terms the Heisenberg’s uncertainty principle states, we cannot determine the position and the momentum ( in other words, speed) at the same time. If we calculate momentum, we cannot calculate the position and vice versa.
Quantum physics is the representation of the smallest things in the universe, and it describes how elementary particles work and interact with light. Quantum physics helps us with the fundamental rules of how the universe works. We do not know the nature of the subatomic particles, but we know they exist.
So how can we do science with them if we cannot see them? The physicists took the mathematical approach on them. It is the story of the “point particle.” Physicists decided that they would pretend a particle is a point in space. For example, an electron is a point with a specific electric charge, and a certain mass and all are indistinguishable with each other.
This way, physicists were able to define and calculate all their interactions mathematically. In other words, this is the definition of “Quantum field theory.” It solved many problems, and all of the standard models of particle physics stands on it. When the calculations of a few quantum properties of electrons are done, the results are accurate up to 0.000000000000.2%. They are not points, but by treating them as points, we get a better understanding of the universe.
Till now, the story is good. We got the right approach, but there is one problem “Gravity.” In quantum mechanics, all physical forces are carried by some particles. However, according to the Einsteins theory of general relativity, the gravity is not like other forces of the universe. In simple words, gravity is the geometry of spacetime itself of distances which we need to describe with absolute precision.
However, as the point articles are free in space, there is no way to measure things with exact precision in the quantum world. When the physicists tried to add gravity to this story with mathematics, the math broke down, and the calculations were very different and inaccurate. It is a massive problem as the particles should obey the laws of gravity and give the same results under gravity as well.
When we combine quantum physics with the standard model, we got the perfect theory of everything. Everything can be proven mathematically with precision. Some of the genius physicists came with a new story, they questioned what is more complicated than a point? A group or set of points or a line or a string. It is how “string theory” was born, which helps us understand everything in this universe.
String theory states that the fundamental elements of the universe are one-dimensional “strings” rather than point-like particles what we observe as particles are vibrations in loops of string, each with its characteristic frequency. In string theory, one of the vibrational states of the string gives rise to the graviton, a quantum mechanical particle that carries gravitational force. By this, we combine the quantum physics and standard model.
It is like a guitar string when pulled instead of making sounds each vibration is a different particle. There are currently ten dimensions in string theory. When we express the particles in all the ten dimensions, Einstein’s relativity equations pop out which are the theoretical proofs of gravity. So this solves the Gravity conundrum of quantum physics.
Thus string theory helps us understand the universe effortlessly and straightforwardly. String Theory contributed to many mathematical approaches which apply to a variety of problems in black hole physics, early universe cosmology, nuclear physics, and condensed matter physics, and it has stimulated several significant developments in pure mathematics.
The drawback of the string theory is that we cannot prove it experimentally as we have learnt that we cannot see the elementary particles. By mathematics, this is the closest theory to the “Theory Of Everything.” It helps us understand the complex universe with an elegant approach.