## Intro

Did you know that there are pretty much only four fundamental forces in nature that we know of? Some physicists claim that there might be a fifth one, but the scientific consensus for now is that we have four.

## What is Force?

Before we look at what these forces are, I want to define what a force is exactly. It is an interaction between physical objects that will change their motion. And motion is just the change of position of some object in a certain environment around a certain time. Think about a car on the freeway. It has motion in one direction, and then if it is hit by another car, bot their motions will change (probably come to a standstill, or fly of the side and do backflips and stuff). You probably already know what force and motion are, but it is good to exactly define what we are talking about, so that we will not run into misunderstandings later on.

## The Fundamental Forces

So, now that we know what forces are, let’s look at these four fundamental forces. The first one is called electromagnetic force. Did you know that electricity and magnets were connected? When a bunch of electrons move through a current (which is how we get electricity), a magnetic field is created. Also the other way around, magnetic fields yield electrical currents. Electricity and magnetism are phenomena that occur from the electromagnetic force at their basis. There was a physicist named James Clerk Maxwell who wrote equations (now called Maxwell’s Equations) that produce a unified framework of how this all works. We use Maxwell’s equations for things like wireless communication and electric motors.

The next force you probably heard of before. Newton thought of this one when an apple fell on his head (even though some historians dispute that this ever happened in this way). The name of this force is of course: gravity. Anything with mass exerts the gravitational force on other things. So as you are reading this, you are exerting gravitational force on your chair or on your screen.

But it is a really weak force (compared to the other forces), so you don’t really notice anything. We only start to notice these forces with really big objects, like the sun and our planet. Even though Newton came up with the theory of universal gravitation, the best theory we have right now that describes it is Einstein’s general theory of relativity. In this theory, gravity is curvature in spacetime. So, you have space and time which are basically interwoven in a sort of fabric, and then gravity is a dent in this fabric. You can kinda visualize it as a ball on a trampoline, where the trampoline represents spacetime.

## Strong and Weak

The third force is called the strong nuclear force, which is around 137 times as strong as electromagnetism, and much more stronger than gravitation. This is the kind of force that holds atoms together. Why do the proton and the neutron stick together in the center of an atom? Well, this is because of this strong nuclear force holding them together. The protons and neutrons are held together by another particle called a meson. This type of particle is a force carrier, it carries the strong force. This strong nuclear force is also what is used to make nuclear weapons, and it is how most of the energy is produced by the sun. So it is not all bad, it is not only used to make weapons, it is also useful for us to stay alive.

Finally, the fourth force goes by the name of weak nuclear force. This type of force is responsible for much of the radioactive decay of particles. So if you have ever heard of radioactivity, for example when nuclear power plants explode or when with the explosion of atomic weapons, then that radioactivity is due to this weak nuclear force. This force is closely related to the strong nuclear force, as you might have guessed by the name. Take for example the nuclear processes in the sun. What happens there, is that particles get smashed together so strongly that the strong force is able to bind them. But this creates unstable particles, but thanks to the weak force, these particles can decay into stable combinations. So thanks weak and strong force, for powering the sun, and giving us light, warmth and life.

Other physics stuff: https://www.polymathuni.com/particle-physics-made-understandable/

Further reading:

https://en.wikipedia.org/wiki/Fundamental_interaction

www.clearias.com/four-fundamental-forces-of-nature/