# 6: The Four Fundamental Forces

- Page ID
- 15037

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The fundamental forces are normally divided in four groups, of the four so-called “fundamental” forces.

- 6.1: Prelude to the Fundamental Forces
- The fundamental forces are normally divided in four groups, of the four so-called “fundamental” forces.

- 6.2: Gravity
- The theory of gravity can be looked at in three ways: (1) The old fashioned Newtonian gravity, (2) Einstein’s theory of gravity and (3)quantum theory. Latter is still under development.

- 6.4: Weak Nuclear Force
- The weak nuclear force is manifests itself through nuclear β decay.

- 6.5: Strong Nuclear Force
- The strong force is what keeps nuclei together. It is described by a theory called quantum chromodynamics (QCD), which described the forces between fermions called quarks that make up the hadrons. These forces are mediated by spin-1 bosons called gluons.

Thumbnail: The Feynman diagram for the weak decay of a neutron.