Kaluza-Klein theory is a classical theory that unifies gravity and electromagnetism by showing that general relativity in 5-dimensions reduces to the equations of 4-dimensional general relativity and the Maxwell equations in 4 dimensions.
kaluza-klein theory is a classical theory that unifies gravity (general-relativity) and electromagnetism (maxwell-equations). Kaluza - Klein theory shows that general-relativity in 5 dimensions is equivalent to general-relatvity plus maxwell-equations in 4-dimensions.
supergravity is an extension of kaluza-klein which also unifies the weak force and the strong force, and with supersymmetry.
