Cosmic Strings: The Hidden Building Blocks of the Universe?

What first comes to mind when you hear about string theory? Is it a theory to play stringed musical instruments? Or is it a way of sewing clothes? Just kidding, it's nothing like that. It is one of the biggest mysteries in the realm of theoretical physics. Some people even consider it to be the last hope of theoretical physics.

What is String Theory?

Imagine you have a cricket ball in your hand. Now what you see is a ball but try to zoom in as much as you can through your imagination. At some point, you will see a cluster of molecules. Now zoom in even further. What do you think you will see? A single molecule. Let's go a bit deeper then. And you see atoms. What are those atoms made of? Zoom in even farther to now. They are made up of a nucleus consisting of protons and neutrons, and that nucleus is surrounded by electrons orbiting it. Since we have come this far, let's zoom in, even more, to know what the building blocks of those protons and neutrons are. And we find quarks. Let's go just one more step deeper to see what's inside the quark. And now string theory suggests we have strings. Surprised? I hope so.

What are these strings? According to string theory, there is a small stringlike filament of energy, and the vibration of this filament in a certain pattern is what is producing the quark which then with other quarks builds protons and neutrons which is the nucleus, and then so on and so forth and we have a cricket ball. And these vibrations have to be in certain patterns to produce a cricket ball. So, a cricket ball is a string vibrating in a certain pattern, an apple is another string vibrating in another pattern. Everything we observe in our existence, as long as they are matter and energy (which is everything by the way), are vibrations of strings, a cosmic symphony. As theoretical physicist Brian Greene said, ”That’s the basic idea of string theory.” Sounds kind of drunk, huh? Well, that’s what string theory suggests. This is one of the most famous, and the most mysterious marvels of modern physics.

Origin of String Theory – The Father

String theory has a very unusual history. It was initially discovered by an Italian theoretical physicist named Gabriele Veneziano in the late 1960s. He was doing a lot of research to understand how the particles inside protons and neutrons behave. How the quarks stay together inside those protons and neutrons. He ended up finding a formula that described the data with great accuracy. But he wasn't sure what the mathematical formula meant. Then subsequent researchers like Leonard Susskind and Holger Bech Nielsen analyzed the mathematical formula and found that the mathematics was describing vibrating strings. So, this idea of string theory came out of an unexpected mathematical investigation.

Why String Theory?

Albert Einstein, one of the greatest scientists that has ever lived, dedicated the later years of his life to finding a very unique theory. One simple but elegant theory to describe everything in existence. It is called the Theory of Everything. Unfortunately, he failed to find such a theory. But the torch has been carried on by many who came after him. And they have led us to string theory. String theory is currently the biggest contender for the theory of everything. There are no known inconsistencies in it. It fits well with the laws of physics and mathematics. It has not been proven yet through experimental and observational evidence, but due to its mathematical consistency, it is a leading contender. So, that's why string theory.

Dimensions in String Theory

We live in a three-dimensional world, and four-dimensional if you count time. But we usually don't notice that because we cannot manipulate time the way we do with shapes. String theory requires higher dimensions. It started with five, and slowly increased to ten and eleven. Some string theorists like to talk about twenty-six dimensions, and some even suggest that there are infinitely many dimensions required to fully grasp the marvel of string theory. These are some pretty interesting and mind-boggling mathematics. Currently, there's more research being done to unravel the mystery.

The Great String Theorists

The are many great string theorists who have contributed to this field. In 1969-70, Yoichiro Nambu, Holger Bech Nielsen, and Leonard Susskind, these men recognized that the theory could be given a description in space and time in terms of strings. Then there’s Michio Kaku and Keiji Kikkawa who came up with the idea of String Field Theory, a different formulation of the bosonic string. Among all these names, the biggest name is Edward Witten. He has contributed the most to this field, and many consider him to be the greatest string theorist of them all. This man has completely revolutionized the way people view the relationship between mathematics and physics. He is also the first physicist to win the Fields Medal, the Nobel Prize for Mathematics. He is also the only person to be awarded the Fields Medal outside of the pure mathematicians.

Has String Theory failed?

One of the problems in string theory is that the full theory does not have a satisfactory definition in all circumstances. Another issue is that the theory is thought to describe an enormous number of different universes, which has led to complications to develop theories of particle physics based on string theory. These problems have led some people in the community to question string theory, and some have even proposed to abandon research on string theory.

My personal opinion on String Theory

For decades physicists have searched for a theory of everything. Einstein lighted the torch, and that will was carried on by many others in the coming days. Then finally, we found a contender, a champion. Even after the lack of experimental and observational evidence, it has been dubbed the M-Theory ('M' stands for 'miracle'). Some even go so far as to call it the theory of the gods. The theory is so beautiful, elegant, and mathematically consistent. Now, what is my opinion on string theory you may ask?

Well, honestly, I don't have an opinion. Because that's not how science works. Science is based on facts and evidence. My personal opinion does not matter here. If string theory is true, if it really is the theory of everything, then one day we will have evidence. We will have conducted experiments that will lead to fruitful results. Only then we will have a final theory of everything. But till then, as far as I can observe, string theory is a strong contender, and I have no issues with admiring its beauty and the way it elegantly describes reality. So, yeah, that’s my view on string theory.

Rafayat Asheque

Rafayat Asheque is a student pursuing a Bachelor of Science in Physics at BRAC University. He is a science enthusiast and also a programmer. He likes reading books, watching movies and web series. He is a big fan of the sci-fi genre and an admirer of philosophy. He plays chess and also watches football occasionally. His dream is to become a researcher one day, and at the moment, he is trying to turn that dream into a reality.