The fundamental forces in physics are often referred to as interactions because they describe the ways in which particles or objects can influence and affect each other. These forces are fundamental because they are considered to be the basic building blocks of all interactions in the universe.
The term "interaction" signifies that these forces are not inherent properties of individual particles or objects but rather arise from their interactions with one another. In other words, the forces are manifestations of the ways in which particles or objects exchange energy, momentum, or other quantities with each other.
Each fundamental force is associated with a specific type of interaction and has its own set of characteristics and behaviors:
Gravity: Gravity is the force responsible for the attraction between massive objects. It acts over long distances and is described by Einstein's general theory of relativity.
Electromagnetism: Electromagnetic force is responsible for interactions involving electric charges and magnetic fields. It includes phenomena such as the attraction or repulsion of charged particles and the behavior of electromagnetic waves. Electromagnetism is described by Maxwell's equations.
Strong Nuclear Force: The strong force is responsible for holding atomic nuclei together. It is incredibly powerful at very short distances and is responsible for binding protons and neutrons in the atomic nucleus. Quantum Chromodynamics (QCD) describes the strong force.
Weak Nuclear Force: The weak force is involved in certain types of radioactive decay and other particle interactions. It is responsible for processes such as beta decay. The weak force is described by the electroweak theory, which unifies it with electromagnetism.
The term "interaction" emphasizes that these forces are not acting on particles in isolation but are the result of their mutual influence. By studying these interactions and understanding the underlying forces, physicists seek to comprehend the fundamental laws governing the behavior of the universe at its most fundamental level.