#488 What are the four fundamental forces?

What are the four fundamental forces? The strong force, the weak force, gravity, and the electromagnetic force.

The four forces are the fundamental forces that govern everything in the universe. They are fundamental because they cannot be broken down into simpler parts and they are the reason behind all of the laws of physics.

Gravity is the weakest of the four fundamental forces. Gravity is the force that one body exerts on another. Everything that has mass has gravity, but the more mass something has, the larger the force of gravity it exerts. The force of gravity has infinite range. Nobody really knows what gravity really is. There is a theory that it could be a subatomic particle called a graviton because all of the other forces are carried by a particle. Gravitons would be the particles that carry the force of gravity, just as photons of light carry the electromagnetic wave. However, gravitons are impossible to observe so we may never know if they are real or not. Gravity is the weakest of the forces by a long way. The next weakest force is the weak force, and it is a billion billion times stronger than gravity. Gravity is so weak that you can defeat the entire gravitational force of a planet the size of Earth by merely lifting your pen off your desk. Why is the force of gravity so weak? There are three possible theories. The first is that there is something in the universe we haven’t yet measured that is affecting gravity. The second is that our measurements are wrong. The third is that there are multiple dimensions and the strongest three forces are limited to our dimension but the force of gravity is shared across all of the dimensions. Gravity as a whole could be the strongest force, but we can only measure the part of it that is in our dimension.

The next weakest force is the weak force. The weak force is responsible for particle decay and radioactive decay. Radioactive decay is when heavy elements become lighter elements or when unstable elements become stable elements. An atom is unstable when it doesn’t have a balance of electrons and protons. If an atom doesn’t have an equal number of electrons or protons, the weak force can change the charge of a neutron to make it into a proton, or a proton to make it into a neutron. The weak force is vital for the nuclear fusion that powers our sun. The sun fuses hydrogen into helium and this leaves an unstable hydrogen atom. The weak force changes some of the protons into neutrons to make the atom balance. The weak force is carried by particles called W and Z bosons. It only works over a very small distance: 0.1% of the diameter of a proton.

The electromagnetic force works between charged particles, such as negatively charged electrons and positively charged protons. Opposite charges attract each other and like charges repel each other. This attraction and repulsion is the electromagnetic force. The greater the electric charge, the greater the attraction or repulsion and the electromagnetic charge has an infinite distance, the same as gravity. The electromagnetic force has two parts. The first part is the electric force. This acts between all particles that have a charge, whether they are moving or not. The magnetic force works on moving particles. The electromagnetic force is carried by particles called photons that have no mass. The electromagnetic force is the reason we have objects in the universe. The phone you are reading this on is made up of materials that are made up of atoms. The hand you are holding the phone with is also made up of atoms. Why don’t the atoms in the phone just fall through the atoms in your hand? The electromagnetic force causes the electrons in the phone to repel the electrons in your hand and the protons in the phone to repel the photons in your hand.

The strong force is the strongest force. It does two things. The first things it does is it holds all of the quarks that make up protons and neutrons together and it holds the protons and neutrons together to make the nucleus of atoms. Without the strong force, we wouldn’t have everything because the atoms would fly apart. This attractive force is strong up to a distance of about 2 femtometer, which is 0.000000000001 mm. The strong force is stronger than the electromagnetic force because it can hold particles together that might otherwise repel each other. The attractive power of the strong force is very strong but, and this is the second thing it does, at a distance of less than 0.7 femtometer, it becomes a repulsive force. It holds one set of particles together to make an atom, but repels any other atoms that come very close. The strong force is what needs to be overcome in nuclear fusion. The sun can do this by being so large that it creates enormous pressure. It forces hydrogen molecules together with such energy that they overcome the repulsive force until the strong force keeps them together. And this is what I learned today.

Sources

https://www.space.com/why-is-gravity-so-weak

https://www.sciencefocus.com/space/gravity/

https://www.quantamagazine.org/gravitons-revealed-in-the-noise-of-gravitational-waves-20200723/