[Encyclios]

Fundamental forces

The fundamental forces, also known as fundamental interactions, are a type of interaction between physical particles that do not appear to be reducible to more basic interactions. Four fundamental forces or fundamental interactions have been identified:

• gravitational interaction (gravity): the interaction between objects due to their mass. Weight is a synonym for the force of gravity;
• electromagnetic interaction (electromagnetism): the interaction between objects due to their charge. All the forces discussed above are electromagnetic in origin except weight;
• the weak nuclear interaction: the interaction between subatomic particles with “flavor” (an abstract quantity that has nothing to do with human taste). This force, which is many times weaker than the strong nuclear interaction, is involved in certain forms of radioactive decay;
• strong nuclear interaction: the interaction between subatomic particles with “color” (an abstract quantity that has nothing to do with human vision). This is the force that holds protons and neutrons together in the nucleus and holds quarks together in the protons and neutrons. It cannot be felt outside of the nucleus.