The Fundamental forces of Nature

Aayushi Tiwari
9 min readSep 7, 2020


Guten tag pals. In another post of scientific revelation let’s dive right into the fundamental forces of nature. As I have said in the previous post after the bang of the Big bang, we have to discuss this topic separately as it is very vast.

We have discussed in the previous post about the early universe, symmetry, CMBR. and fundamental particles. To take a cue from here we shall focus on the fundamental forces of nature. There are four forces of nature; Gravitational force, electromagnetism, weak force, strong force. In case you people are wondering why I chose the universe as my recent series as my previous posts are about hominin evolutions and human development. The chronology of the universe has always been a confusing and intriguing topic for me. The most difficult part was to arrange the jumble of events according to what happened before what. If you know the order of the events, it’s a lot easier to understand. That is how I got this idea of writing the posts on, since the big bang to the formation of the earth.

The universe is full of miracle things patiently waiting for our wits to grow sharper.

Eden Philpotts

The fundamental particles of nature

In my previous post also I have included a section about fundamental particles. It is important to discuss it before we jump into the main topic because these are somewhat the same concepts.

So, after thorough research and studies through centuries our ideas about the building blocks of the universe had changed dramatically. From the ideology that our world is made up of 4 elements fire, earth, water, and sky, we have reached in the era of subatomic particles. We have quarks that are building blocks of protons and neutrons. Protons and neutrons constitute atomic nuclei. Electrons with negative charges revolve around the nucleus that carries a positive charge. Quarks have 6 types up, down, charm, strange, top, and bottom. Every matter in our universe carries two up and one down quark in its proton. In addition to it, every neutron carries two down and one up quark. The other quarks are so unstable that they could not combine to form any matter. They were detected in particle colliders.

Scientists have found evidence of Neutrinos another kind of fundamental particles. It is very hard to detect them because they rarely interact with other particles. There are 3 kinds of neutrinos. firstly electron- neutrino which is the simplest and least heavier. The second and third ones are muon-neutrino and tau-neutrino respectively. CMBR is the most ancient observation of the universe. Scientists are devising machines to observe neutrinos which will tell us an even more ancient picture of the universe. In the 1930s we found heavier cousins of the electron, the muon, and tau. Along with these particles, antiparticles have also been detected.

At the beginning of the universe just after the big bang when the particle was emerging after the conversion of energy, they were in pairs. One particle and its antiparticle. With election we had positron. With quarks we had antiquarks. Particles and antiparticles should remain away from each other or else they will annihilate in the burst of energy. Most of the matter and antimatter had annihilated as energy but some matter manages to remain. There must have some differences in the number of pairs or matter percentages. If matter and antimatter had been equal, no matter have survived to form galaxies, stars, black holes planets, and us.

This section has inspired by The elegant universe by Brian Greene and The brief history of time by Stephen Hawking.

Gravity as the first fundamental force

I vaguely remember thinking why gravity is so special. I have always preferred electromagnetism especially the magnetism element. For instance, I remember playing with magnets. It was very fascinating how they stick to the iron of doors and refrigerators. We feel and see electromagnetism all around us. On very dry days we used to tear the papers in small pieces. With the help of a plastic scale after rubbing it against hairs, we would see how it attracted the paper. There are countless childhood plays. On the other hand, imagining gravity was a tough task but the importance of gravity for our daily life is often ignored.

It’s the cause of friction. You are able to walk on the earth just because of gravity. Gravity is responsible for our bone shape and structure. If gravity would be a little higher on earth we would have been crawling near the ground, very much like snakes. If gravity would have been lower, all of us have body structure like slender man, literally. Try writing on paper after putting it against a wall. You will notice after a few words your pen had stopped working. It happened because of a lack of friction that ultimately depends on gravity.

Newton had given his famous explanation about how gravity increases with mass and decreases with distance. Gravitational force is the weakest and thought to be carried by graviton. It is always attractive and that’s why over large distances it dominates the universe.

Whatever we are looking at into the night sky is a result of gravity. Go out in the night and look towards the sky. You will see the constellation of stars, neighboring galaxies, and the milky way. The existence of the sun, moon, and earth is due to gravity. Without gravity, nothing would have been possible. Other forces can be attractive or repulsive but gravity is only attractive and as mass increases its effect increases. For example black holes that have whooping gravity in minuscule areas. Graviton carries the force and it is a spin 2 particle. Although scientists haven’t detected a graviton yet but it is thought to be massless. The particles of heavenly bodies(stars, planets) exchange gravitons among themselves and that is how they exert force. These gravitons form gravitational waves that are very hard to detect. They were first detected in 2017 by the LIGO detector.

Secondly, we have Electromagnetism…

The game with magnets had fascinated me a lot. The best parts were playing with 2 opposite magnet when they repel each other. It was mind-blowing how they used to repel. It was shocking however force I will put they never bugged. I used to wonder where they got this power from. Electromagnetism is the most visible force that is present everywhere. It affects charged particles like electron and quarks which form protons. There are two types of electric charges positive and negative. Two positive charges repel each other, similarly, two negative charges repel each other.

On the small scale of quantum, forces like electromagnetism dominate. It is carried by massless particle photons. When a photon collides with an atom, the electron absorbed the energy and moves to the higher orbit. When this electron jumps back to its original orbit it releases the photon. It is the force behind almost every modern technology and weather events. It affects every dimension of our modern lifestyle.

Weak nuclear Force portrays the third one

Thirdly, comes the weak nuclear force, and as understandable from the name it works at the quantum level. It works on the particles with 1/2 spin. It is carried out by weak gauge bosons and responsible for radioactivity. There are 3 types of bosons, W plus, W minus, and Z naught.

The weak nuclear force is responsible for particle decay. Without it, stars would have never shinned because at the center of a star’s core hydrogen changes into helium through particle decay. Our radioactive elements also require weak nuclear force. As in strong force have quarks change colors. In weak force, we have quarks changing flavors. Up, down, strange, charm, up, and bottom. Up and down quarks have the smallest mass. Weak force can change neutron into protons and vice versa through particle decay. It operates at a very small range. The weak force is very rare to observe in nature because its energy requirement is very high. In nuclear decay which is also called Beta-decay neutron changes into protons.

For Example is carbon 14 decay, which helps us in the carbon dating of objects to figure their ages. During beta decay neutron emits a W particle that further decays into electrons and neutrinos. A W particle has a huge mass of 156000 electron volts in these types of decay. This energy requirement cannot be fulfilled easily and that’s why weak interactions are rare. Top quarks also decay in the same way into bottom quarks after emitting W bosons. Top quarks have high energy, so its decay is normal and W particles are emitted. In fact, this decay is so fast because at this level weak nuclear force is dominant.

Strong nuclear Force as the fourth fundamental force…

Lastly, we have a fourth force, the strong nuclear force. It is responsible for keeping quarks together inside protons and neutrons. It also holds protons and neutrons within atomic nuclei. Gluons carry the strong nuclear force. It is a spin 1 particle and only interacts with quarks and itself. As usual, it is difficult to imagine this force. But we all can understand its importance. There would have been no atoms to form stars and galaxies without a strong nuclear force.

The strong force keeps neutron and protons intact. Protons and neutrons (collectively called hadrons) are made up of quarks that have properties like colors. It means they have quantum states called green, blue, and red. The combination of these colors always has to add up to white. That means in a proton and neutron we have 3 quark of each color. Quarks constantly change colors with the help of gluons. Gluons don’t have mass or electric charges but it does have colors. It changes the color of gluons as it leaves one and goes onto another one. Even after all this color changing, the net color of hadrons (protons and neutron) has to remain white.

Gluons act like rubber bands to keep quarks together. Quarks can move around the hadrons freely but if they move a lot away they are bought back by the strong force. Strong force becomes stronger as quarks move away from each other.

To get you an idea about strong nuclear force lets think about the helium atom. It has two protons and two neutrons. Protons have positive charges so originally they should repel each other (electromagnetism), but they are obliged to glued inside nuclei. The strong nuclear force is repulsive over short distances so it keeps neutrons and protons away from each other. It gives a space between them which gives the size of nuclei. It is also stronger over slightly larger distances as mentioned above.

Now the strong force is very strong so, it creates another carrier particle outside the protons and neutrons, Pions. They have two quarks of different colors. Pions work outside of protons and neutrons. As gluons carry the force inside hadrons, pions carry it outside among neighboring hadrons.

Do watch these 2 videos by the Scishow; Strong interaction part 1 and Strong interaction part 2

Comparision data on the fundamental forces

Additional resources for more…

  1. Read the post on fundamental forces of nature by
  2. Watch a youtube video on fundamental forces. For instance, fundamental forces by the seeker and Michio Kaku
  3. If you want to know about these forces very simply then read this post by Science alert.

In conclusion, there is so much to discover about fundamental forces. The standard model by CERN will help you understand the interaction between forces and particles. Stay tuned and do the Revelation.

Closed in the room, my imagination becomes the universe, and the rest of the world is missing out.

Criss Jami



Aayushi Tiwari

Hey everyone. I am a bibliophile and love writing. I am trying to sharpen my hobby of writing regularly. I am always up for new things to learn.