Changes

==History==

==History==

A "field theory" describes a force on a particle in terms of its position, or location in a "field".  An example of a field theory is [[James Maxwell]]s theory of [[electromagnetism]].  Subsequent field theories are the [[theory of relativity]], and modern quantum field theory.

A "field theory" describes a force on a particle in terms of its position, or location in a "field".  An example of a field theory is [[James Maxwell]]'s theory of [[electromagnetism]].  Subsequent field theories are the [[theory of relativity]], and modern quantum field theory.

[[Isaac Newton]]'s (classical) theory of [[gravity]] is also considered a field theory, but it is based on "[[action at a distance]]" and does not have a force field.  To the extent that a field theory has come to imply the existence of a force field, Newtonian gravity would not be one.

[[Isaac Newton]]'s (classical) theory of [[gravity]] is also considered a field theory, but it is based on "[[action at a distance]]" and does not have a force field.  To the extent that a field theory has come to imply the existence of a force field, Newtonian gravity would not be one.

Newton described the force on a particle as related to the product of the particles mass <math>m_1 \ </math> and its distance from another mass, <math>\frac{m_2}{r^2} \ </math>.  This is called a field theory because regardless of the first particle, the second gives rise to a "field" everywhere in space which would affect any particle at any position.

Newton described the force on a particle as related to the product of the particles mass <math>m_1 \ </math> and its distance from another mass, :<math>\frac{m_2}{r^2} \ </math>.   

 

This is traditionally called a field theory because regardless of the first particle, the second gives rise to a "field" everywhere in space which would affect any particle at any position.

[[Category:physics]]

[[Category:physics]]