Four fundamental forces of nature are gravitation, electromagnetism, strong nuclear force, and weak nuclear force. These interactions are regarded in modern physics as the basic mechanisms through which all known physical processes occur. Every observed interaction in matter and energy can be traced to one or more of these forces.
Gravity (Gravitational Force) - Gravity is the interaction between objects that possess mass or energy. It governs the motion of planets, stars, galaxies, and other large-scale structures in the universe. According to the general theory of relativity, gravity results from the curvature of spacetime caused by mass and energy. Gravity has an effectively infinite range and is the weakest of the four fundamental forces at the scale of elementary particles.
Electromagnetic Force - Electromagnetism acts between electrically charged particles and is responsible for electricity, magnetism, light, radio waves, X-rays, and chemical bonding. It is mediated by photons and can both attract and repel because electric charge exists in positive and negative forms.
Strong Nuclear Force (Strong Interaction) - The strong interaction binds quarks together to form protons and neutrons and also binds protons and neutrons within atomic nuclei. It is mediated by particles called gluons and is described by the theory of quantum chromodynamics. The strong force is the strongest known fundamental interaction at subatomic distances, but its effective range is extremely short, mainly limited to the dimensions of atomic nuclei. Without the strong interaction, stable atomic nuclei could not exist.
Weak Nuclear Force (Weak Interaction) - The weak interaction is responsible for certain forms of radioactive decay, including beta decay, and plays a critical role in nuclear reactions inside stars. It is carried out by the W and Z bosons. Unlike the electromagnetic and strong interactions, the weak interaction can change one type of elementary particle into another. The weak force has a very short range because its mediating particles are massive.
