Editing Mechanics (section)

=== Relativistic ===
{{main|Relativistic mechanics}}
Akin to the distinction between quantum and classical mechanics, [[Albert Einstein]]'s [[General relativity|general]] and [[Special relativity|special]] theories of [[theory of relativity|relativity]] have expanded the scope of [[Isaac Newton|Newton]] and [[Galileo]]'s formulation of mechanics. The differences between relativistic and Newtonian mechanics become significant and even dominant as the velocity of a body approaches the [[speed of light]]. For instance, in [[classical mechanics|Newtonian mechanics]], the [[kinetic energy]] of a [[free particle]] is {{math|1=''E'' = {{sfrac|1|2}}''mv''<sup>2</sup>}}, whereas in relativistic mechanics, it is {{math|1=''E'' = (''γ'' − 1)''mc''<sup>2</sup>}} (where {{math|''γ''}} is the [[Lorentz factor]]; this formula reduces to the Newtonian expression in the low energy limit).<ref>{{cite book |last1=Landau |first1=L. |last2=Lifshitz |first2=E. |title=The Classical Theory of Fields |date=January 15, 1980 |publisher=Butterworth-Heinemann |page=27 |edition=4th Revised English}}</ref>

For high-energy processes, quantum mechanics must be adjusted to account for special relativity; this has led to the development of [[quantum field theory]].<ref>{{cite book |last1=Weinberg |first1=S. |title=The Quantum Theory of Fields, Volume 1: Foundations |date=May 1, 2005 |publisher=Cambridge University Press |isbn=0-521-67053-5 |page=xxi |edition=1st}}</ref>