There are four forces that physicists call fundamental in the world: gravity, electromagnetic force, weak force, and strong or nuclear force.

Today I want to talk a little about this last, strong or nuclear force or strong nuclear interaction. And the first thing is to define that it is a force.

Although it may seem simple at first, the definition of force has varied over time according to the scale to which it has been viewed, so there is a “classic” definition and one (the current one) called “mathematics”.

Starting from the back, the mathematical definition of a force gives us the amount in which two elements interact with each other. As quantity, it is a mathematical model that is usually represented by a vector (you know, a magnitude that has an application point and a vector that indicates the quantity and direction in which it is made) and therefore, by the vector, We have the classical definition of force that is something that alters the position of an object.

Returning to the subject of strong interaction, the definition known by any physicist is the force that unites the elements within an atom, that is, within the nucleus, which joins protons, neutrons and, therefore, the elements that compose them, Quarks. That is, strong nuclear interaction is so called because it is the force with which the elements of the nucleus of the atom interact.

The more “advanced” physical explanation tells us about quantum chromodynamics, that is, the part of quantum physics that studies the dynamics of elementary particles. And in fact, it does not speak of forces, but of energy. That is to say, what it indicates to us is that the particles are held together due to the non-variation of the energy existing in the nucleus.

In a gross way and without going into details we are told that fermions (elementary particles) are made up of two parts, quarks and gluons. If the quarks is the mass of the particles, the gluons are the forces of these particles and, therefore, their energy. The gluons have a thing called color that is nothing more than the type of charge they have. The interaction between the gluons is precisely what makes the particles stay together. So as the fundamental particles are united thanks to the forces of the gluons, the parts of the atom that are formed by elementary particles, are united thanks to these forces.

**It’s fun!**

If you want to know more about this, in quantum theory books you have more information, for example in the Introduction to Quantum Mechanics by David J. Griffiths is a good start to take a look.

ut the University Physics with Modern Physic from Young and Freedman can help you “get in” A little in this fun and not as complex world, as many believe.

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