Forces we experience everyday, such as our weight, are macroscopic manifestations of fundamental interactions taking place in the particles world. Nowadays, we know four fundamental interactions ways between particles. They are named like that since any other kind of interaction can be explained based on these four ways

Among the four fundamental interactions, only gravitational interaction and electromagnetic interaction are revealed to our senses. The effects of the other two interactions are insignificant in the macroscopic world (the one we can see at firs sight).

Gravitational interaction

This kind of interaction is responsible for the maintainance of the strucutre of the universe, star formation, planets formation, etc. It is an infinite – range attractive - repulsive interaction among all bodies with mass. It is the weakest fundamental interaction since it has got an intensity 10-39 lower than the strong nuclear force, so the microscopic world can be expressed without it. Therefore, this intensity decreases quickly with distance. Just like all the interactions between bodies, this interaction is explained by the particle exchange mechanism, gravitones are the particles exchanged on this type of interactions.

Electromagnetic interacion

It is responsible for maintaining the structure of the matter, the electromagnetic is an an infinite – range attractive interaction that it is produced among bodies electrically charged. The attraction or rejection is produced depending on the sign of the electrical charges of the bodies in interaction. Different charges of different sign attract themselves and charges of equal sign reject themselves. Its intensity is about 100 times less intense than strong nuclear force, but it is much more intense than gravity.

It is responsible for keeping electrons orbiting around the nucleus of the atoms and let them join other atoms to form molecules.

Exchange particles on this kind of interaction are called photons.

Strong nuclear foce

Strong nuclear force is responsible for keeping the stability of the atoms ́nucleus, maintaining united the protons and neutrons that make it up. It is attractive, it has a scope not higher than 10-15 m and it is the most intense fundamental interaction.

The exchanged particles on this type of interaction are called mesons and gluons.

Weak nuclear force

It is responsible for certain radiactive phenomenons. Its range is not higher than 10-17 m and its intensity is 10- 14 times smaller than strong nuclear force ́s intensity. Exchanged particles on this kind of interaction are called bosons W+, W- y Z0.

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