Standard model explained in simple way! | All 4 fundamental forces explained !

The image below is of the most successful scientific theory of all time ! "The standard model"

Credit:- Quanta magazine

The standard model describe how everything in universe is made of 12 different types of matter particles, interacting with three forces and all bound together by a special particle called Higgs boson. 

Well! Actually we have 4 fundamental forces, it's gravity the force which we understood the least, the reason why we didn't included it in standard model is, at the microscopic level force of gravity is so weak that it barely has any effect on a single subatomic particle. It's not included also because the theory which defines gravity is general relativity and we don't know how to incorporate it. 

The standard model is written in a language known as Quantum field theory. It tells us, matter at a fundamental level is not really made up of particles. Instead its made up of fluid like objects which are spread throughout all of universe. The most important classification of standard model is, every particle is either a fermion, which is a matter particle or a boson, the force particle. 

The difference between the fermion and a boson is, fermions must obey Pauli exclusion principle which prohibits 2 fermion to be on top of each other. On the other hand, boson can file on top of each other as much as they want because they do not follow the Pauli exclusion principle. 

Fermions 

Everything here can be reduced to just 3 more, electron, up quark and down quark. Protons has 2 up quark and 1 down quark and a neutron has 2 down quark and 1 up quark. When we put proton and neutron together we have nucleus and add electrons to it then we have an atom and put atoms together that's what we are made of, matter.

Let's talk about nutrino. The fourth type of matter particle. A neutrino is extremely light and barely interact with anything. About 100 trillion neutron of passes through our body every second. Most of them come from sun but many of them has been streaming through universe. So till now we understood four particles, up quark down quark electron and neutrino. By the combination of these four particles we get 2 new particles  muon and tau. 

Muon and tau behaves exactly like an electron, but they are heavier. The muon is approximately 200 times heavier but the tau is about 3000 times heavier. The same goes for quark, 2 heavier versions of the down quark exist called strong and bottom quark. Also 2 heavier versions of up quark are charm and top quark. There are even 2 more versions of neutrino, muon neutrino and tau neutrino. Did you know, electrons, up quark and down quark are first generation particles.

How can we create second and third generation particles? We can create second and third generation particles but they are unstable because they decay quickly. The first generation particle scan be detected in particle accelerators. The photographs have also been taken of the tracks they left behind. 

Why particles have to come in a set of 4 ?

There is a mathematical consistency in the standard model that tells us that we can't have one particle without the other three. We really don't understand why there are three generations. That remains a complete mystery.

There is also mathematical theory where all particles are described by exact same equation

The equation was written down by paul dirac  to describe the electron. Also newly discovered particles such as quarks and neutrinos are described by the dirac equation. But here we are missing something and that's forces. 

There are three fundamental forces in the standard model:-

1. Electromagnetism

2. Strong force 

3. Weak force

Which of the particles come with the associated particles "boson's". Bosons are force carrying particles. For example:- you can think of fermions as constantly swapping bosons between them affecting their motion and providing us with force. 

1. Electromagnetism is responsible for the chemical properties of the elements and we have created much of modern technology with the help of it. It acts on anything that carries electric charge that is, it acts on the electron type particles and the quarks but not on the neutrinos because neutrinos are electrically neutral.

Mathematical formula:- 

The electrostatic force between two charges extends to infinity. This means the charged particle on earth has a non zero affect on a charged particle near Jupiter also other charged particles in the universe. This force is 10³⁶ times greater than gravitational force. Why isn't electromagnetism is most dominant force in universe? This is because on large scale electric charges of large objects tends to cancel out each other. So, in general large objects remains neutral. But, this force does not have a big influence in our universe. It is responsible for the nature of light and also for all the biochemistry happening. We can say that electromagnetism is basics of chemistry.

2. This force acts only on quark and on particles like protons that are made of quark. The strong force holds the nuclei of atoms. Just as the photon is associated to electromagnetism, there is a particle gluon associated to strong force because it stick quarks together. 

As an electron in space gives out electric field same quark will give give out gluon field. Here unlike electromagnetism, the field doesn't spread out radially but quark produce a thin flux tube, a string like object which can only end when it finds a different quark. Now, you may be wondering what keeps positively charged protons held together in the nucleus of atoms? Also, if we do the calculations, two protons in helium atom experience the force equal to 20 pounds approximately [9.07 kg]. 

This is a huge force for something smaller than an atom. So, why don't the ripple each other and fly apart instantly. Here comes the strong force, the reason why protons don't fly a part. The strong force his hundred times stronger than electromagnetism. Strong force extends as far as the width of proton. The force is responsible for holding electrically neutral neutrons in the centre of atoms as well. Even though we can't experience this force directly, the world has experienced it's affect, the release of this force is the energy behind nuclear bombs. The fission and fusion of atoms release huge amount of binding energy from the nucleus of atoms, which formed the strong force. The energy of this force is responsible for most of the mass of any object, not the Higgs field as you might have thought. When energy is released, the mass of the atom is converted to energy in nuclear reactions.

3. Weak force

The week for scan change identity of quarks. For example, a down quark can turn into a up quark releasing an electron and a neutrino. The weak forces responsible for nuclear fission reaction that powers the sun and provide energy. The weak forces is also the reason that heavier matter part like muon and the strange quark, quickly decay into the 3 lighter and more stable fermions that make up matter. It's the only force that neutrinos feel. Also there are particle associated to weak force and we called this w  and z bosons.

Higgs boson 

On July 4, 2012, scientists announced the observation of the Higgs boson, the particle that gives almost all particles "mass". Higgs boson is special because of the fact that none of the fundamental particles in the world have mass. Infact, the equations of standard model prohibits the particles from having any mass! Massless particles, like the photon are obligated to travel at the speed of light. So, why don't matter particles fly around massless at the speed of light ? This is higgs boson comes in. It endows all fermions with a mass. The reason for this doesn't have to do with the particle itself, but rather the higgs field has permeates the universe.

Higgs field as something like a cosmic massless, trapping matter particles as the travel through space and giving them a mass. We have known about the effects of Higgs field for a long time. But experimental confirmation in 2012, when the large hadron collider at CERN was able to smash protons together at high enough energies to cause a ripple in higgs field, that's the particle that we call the higgs boson.

So this is the standard model, 12 matter particles interacting with 3 forces and a higgs field.

Spin: 0

Mass: 125.25 ± 0.17 GeV/c²

(More about Higgs later)

For more and better understanding of quantum mechanics we suggest you to read:-  Quantum mechanics explained! Phymathinfo