"Exploring the Building Blocks of Matter: Quarks, Leptons and Fundamental forces"

Welcome to our blog, where we explore the fascinating evolution of our universe since the Big Bang. In our previous two blog posts, we discussed the stages of the universe's evolution in "Formation of our Wonderful universe", and provided a timeline of the major cosmological events that have taken place since the Big Bang in "Cosmic Calendar".

However, for further understanding of the universe's evolution, we must first delve into the elementary and fundamental particles that existed before the universe's formation. This blog will serve as an introduction to these particles and their role in the universe's evolution. By understanding the basic building blocks of the universe, we can better comprehend how the universe has evolved into the complex and awe-inspiring entity we see today.

Image obtained by simulating the standard model of particle physics

Particle :

The field of particle physics deals with the study of the interactions between particles on the most fundamental level. It involves understanding the building block of atom, which are made up of a nucleus and electrons. The nucleus itself is composed of protons and neutrons, and changing the number of these particles can result in different types of atoms or nuclei. However, there are only 118 stable elements in the periodic table, indicating that here are certain conditions required for a nucleus to exist

For many year, we believed that electron, proton and neutrons and electron were the fundamental building blocks of matter. However, with advancements in particle physics, we discovered that protons and neutrons, in turn, are made up of even smaller particles known as quarks. The concept of quarks is quite intriguing, as they are believed to be the fundamental building blocks of matter. But what exactly are quarks? How did we discovered their existence and what is their role in particle physics?

Quarks :

 In the 1960s, Murray Gell-Maan and George Zweig proposed a theory that protons and neutrons, which are part of hadron family, are made up of even smaller fundamental particles. They called these particles as Quarks.

Gell-Maan classified quarks into three types : Up quarks(u) , down quarks (d) and strange quarks(s). Later , Glashow and Bjorken added a fourth type called the charm quark(c). In 1975, Haim Harari extended the theory to propose the existence of two more types, the top quark(t) and the bottom quark(b). 

The proton and neutron are made up of three quarks each. The proton consist of two up quarks and one down quark, while the neutron consists of two down quarks and one up quark. It is important to note that the quarks and electrons are the fundamental particles, not the proton, neutron and electron. 

In addition to quarks and electron, there are other fundamental particles such as neutrinos (will talk about neutrinos when we discuss the formation of matters and stars), which have similar properties to electrons. The family of electron, muon and tau along with their respective neutrinos, are called Leptons (All Leptons have similar spin quantum number {1/2}). Together, quarks and Leptons are identified as fermions.

Classification of Fundamental matters

Overall, the discovery of quarks has led to a deeper understanding of the building blocks of matter and the complex interaction between particles on a fundamental level

The up quark and down quark, which make up the proton and neutron, and the electron and associated neutrino, are just one generation of fundamental particle; the lightest in mass. For an unknown reason Nature also contains two sets of heavier doppelgangers, shown here as generation 2 and 3, the larger bricks. These particles are only created at very high energies, such as those generated in particle accelerators and which existed early on in the history of our Universe

Quantization of Force Fields :

The study of the fundamental forces that govern our universe has always been a topic of great interest among physicists. In the early 19th century, Michel Faraday's experiments and James Clerk Maxwell's mathematical insights led to the discovery that forces are exchanged through waves. With the development of quantum mechanics in the early 20th century, the wave-particle duality principle revealed that anything in our world can exist in a particle or wave form depending on certain conditions.

In 1960s, the theory of Quantum Electrodynamics (QED) was established, which suggested that the force between charged particles is exchanged by particles called photon, which are massless particles of light. This theory was supported by Hideki Yukawa'a Meson theory of nuclear forces, which proposed that the exchange of particles called mesons between electrons and neutrons is responsible for nuclear force.

Imagine you have a magnet and an irone piece. According to classical theory the interaction between them is due to the electromagnetic radiations but, according to QED, the magnet and iron piece are exchanging photons, and it's the exchange of photons that causes the iron piece to get attracted towards the magnet. The study of fundamental forces and their interactions continues to be a fascinating filed of research in physics.

In order to understand how the exchange of particles works in the quantum theory of forces, let's consider an analogy of two boys playing with basketballs or volleyballs. When they throw the balls at each other, the boys move backward as they catch the ball thrown at them which is because at this moment the backward momentum increases. This method of exchanging basketballs has the same effect as a repulsive force between the boys. On the other hand, if the boys snatch the basketballs from each other's hands, the result will be equivalent to an attractive force acting between objects, resulting in either an attractive or repulsive forces.

Field Boson (Carriers of the interactions) :

All fundamental particle the smallest building blocks 

The mutual forces between two particles can be regarded as being transmitted by the exchange of other particle between them. This concept applies to all fundamental interactions. The particles exchanged are called bosons. Bosons, the particles responsible for mediating the fundamental forces, are divided into two categories - filed bosons and mesons. Filed bosons are responsible for interactions in force fields, while mesons mediate interatomic and subatomic interactions. All fundamental particle only interact with certain field bosons, which are listed below in the chart

Complete chart of all the fundamental particles and their field of interactions 
here strong force associates with forces to hold nucleons and
weak force associates with force between the nucleons and leptons   

In Conclusion, the study of particle physics has given us a deeper understanding of the building blocks of matter and the fundamental forces that govern our universe. From the discovery of quarks to the development of quantum field theory, our understanding of the subatomic world has evolved significantly over the years. As we continue to delve deeper into the mysteries of particle physics, we can expect to make more groundbreaking discoveries in the future. 

I hope this blog has provided you with a new perspective on the fundamental building blocks of matter and the interactions between them. Particle physics is an intriguing and ever-evolving field of study, and there is so much to explore. Stay Connected for more blog's in this series, where we will delve into the formation of fundamental particles in the early universe and the mysteries surrounding dark matter and dark energy.

Thankyou for Reading!