Editing Line element (section)

{{Short description|Line segment of infinitesimally small length}}
{{about|lines in mathematics|Long Interspersed Nuclear Elements in DNA|Retrotransposon#LINEs}}

In [[geometry]], the '''line element''' or '''length element''' can be informally thought of as a line segment associated with an [[infinitesimal]] [[displacement vector]] in a [[metric space]]. The length of the line element, which may be thought of as a differential [[arc length]], is a function of the [[metric tensor]] and is denoted by ''<math>ds</math>''.

Line elements are used in [[physics]], especially in theories of [[gravitation]] (most notably [[general relativity]]) where [[spacetime]] is modelled as a curved [[Pseudo-Riemannian manifold]] with an appropriate [[metric tensor (general relativity)|metric tensor]].<ref name="WheelerMisnerThorne">Gravitation, J.A. Wheeler, C. Misner, K.S. Thorne, W.H. Freeman & Co, 1973, {{isbn|0-7167-0344-0}}</ref>