Four interactions or forces govern all known phenomena in the universe


  • Electromagnetism acts on electric or magnetic charges. This force holds together atoms and molecules and is responsible for all chemistry. The force carrier is the photon. Molecular forces are residual electromagnetic forces.  Also responsible for all macroscopic electric and magnetic phenomena, TV, radio, light, communication, lasers, etc.. The quantum theory of electromagnetism is called quantum electrodynamics or QED for short.
  • Strong force, acts on  color charges. This force confines quarks inside particles. The force carriers are 8 gluons. The nuclear force that hold the nucleus together is residual strong force. The nuclear energy radiated by stars mainly through the nuclear fission processes is energy stored by the strong force. The quantum theory of the strong force is called quantum chromodynamics or QCD for short.
  • Weak force acts on "weak" charges. This force is responsible for decay of particles and change of "flavor". The decay process also contributes to the energy radiated by stars, including the Earth. The force carriers are W+,W-,Z0. The Weak and Electromagnetic forces are unified at 10-18 meters (one thousandth the size of a proton). This is explained by the Standard Model and is called the unified electroweak force, and its quantum theory is called quantum flavordynamics of QFD for short. QFD contains QED.
  • Gravitational force acts on mass or energy. This force holds people on Earth, planets around the Sun, stars in galaxies, governs the expansion of the universe as a whole, is responsible for quasars, supernovae, black holes, bending of light around stars, . The quantum of gravity, the graviton, has not been seen in experiment yet.