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{{Short description|Branch of differential geometry}} {{hatnote|[[Elliptic geometry]] is also sometimes called "Riemannian geometry".}} ...

| caption = The [[Metric system|metric]] length of one [[kilometre]] is equivalent to the [[imperial measurement]] === Euclidean geometry === ...

...-spacetime) ''source-free'' [[Maxwell equations]] appropriate to the given geometry. For this reason, electrovacuums are sometimes called (source-free) ''Eins ...interpreted as a curved spacetime, and which is specified by defining a [[metric tensor]] <math>g_{ab}</math> (or by defining a [[frame fields in general re ...

...]]s, etc.), [[Topology|topologies]], [[Metric space|metric structures]] ([[Geometry|geometries]]), [[Order theory|orders]], [[Event structure|events]], [[equiv {{see also|Outline of geometry|Outline of trigonometry}} ...

In [[differential geometry]] and [[theoretical physics]], the '''classification of electromagnetic fie ...etic fields characterizes the bivector ''F'' in relation to the Lorentzian metric {{nowrap|1=''η'' = ''η''_''ab''}} by defining and examining the s ...

| From left to right: a [[square (geometry)|square]], a [[cube]] and a [[tesseract]]. The square is two-dimensional (2 {{General geometry|concepts}} ...

...el. Ellis proposed a proof of this equation in the context of [[Riemannian geometry]].<ref>G. F. R. Ellis, "Relativistic cosmology", ''Proceedings of the 47th ...ered to be true when photon number is conserved, gravity is described by a metric theory with photons traveling on unique null geodesics.<ref>{{cite journal ...

...ectromagnetic tensor]]) can be written as a 2-form in Minkowski space with metric signature {{math|(− + + +)}} as ...our dimensions even by any metric [[conformal geometry|conformal]] to this metric). The fields are in [[natural units]] where {{math|1=1/(4''πε''₀ ...

...]] continuum containing [[position (geometry)|positions]] and [[direction (geometry)|directions]].<ref>{{cite encyclopedia|url=http://www.britannica.com/eb/art ...turies mathematicians began to examine geometries that are [[Non-Euclidean geometry|non-Euclidean]], in which space is conceived as ''[[space curvature|curved] ...

...rmations by reciprocal radii" in relation to the framework of [[Lie sphere geometry]], which were already known in the 19th century. Time is used as [[Spacetim A special case of Lie sphere geometry is the [[#Transformation by reciprocal directions|transformation by recipro ...

...ol t and defined according to 1&nbsp;t = 10<SUP>3</SUP>&nbsp;kg is called 'metric ton' rather than 'tonne.'"[https://nvlpubs.nist.gov/nistpubs/SpecialPublica * The geometry of the towing line must have a well-defined value. Ideally, one would expec ...

...[particle velocity]], at a point on the surface in the direction [[Normal (geometry)|normal]] to the surface, [[Surface integral|integrated over]] that surface ...ed to produce. The [[A-weighting]] scale is used in the calculation as the metric is concerned with the loudness as perceived by the human ear. Measurements< ...

...ontrol of electromagnetic fields. It was constructed of a thin [[cylinder (geometry)|cylinder]] at 21.6 centimeters in [[diameter]] comprising 60 concentric ri ...ansformation optics were employed to mimic a black hole of [[Schwarzschild metric|Schwarzschild form]]. Similar properties of [[photon sphere]] were also fou ...

[[Image:Cross-flow.svg|right|300 px|thumb|Cross-flow geometry]] [[Image:Dead-end.svg|right|300 px|thumb|Dead-end geometry]] ...

...[[space]], [[time]], [[Motion (physics)|motion]], [[length]], [[Position (geometry)|position]], [[velocity]], [[acceleration]], [[mass]], [[momentum]], [[Forc ...zian manifold]], [[Lorentz transformation]], [[Metric (general relativity)|metric]], [[Minkowski diagram]], [[Minkowski space]], [[principle of relativity]], ...

...metre|fm]]².<ref>{{SIbrochure8th|pages=127–28}}</ref> Smaller [[Metric prefix|prefixed]] units such as [[Milli-|mb]] and [[Micro-|μb]] are also wi ...oss section for particles is generally different from the [[Cross section (geometry)|geometrical cross section]] of the particle, and it depends upon the [[wav ...

...Hiley: ''Phase space description of quantum mechanics and non-commutative geometry: Wigner-Moyal and Bohm in a wider context'', in: Th. M. Nieuwenhuizen et al ...al plays the role of an internal energy<ref>B. J. Hiley: ''Non-commutative geometry, the Bohm interpretation and the mind–matter relationship'', [http://www.bb ...

...s and physics)|vector]], or [[tensor]], that has a value for each [[Point (geometry)|point]] in [[Spacetime|space and time]].<ref name=Gribbin>{{cite book |aut ...eory. Here the principal field is the [[metric tensor (general relativity)|metric tensor]], a symmetric 2nd-rank tensor field in [[spacetime]]. This replaces ...

...l [[vector area|vector element]] of surface area {{math|''S''}}, [[Normal (geometry)|normal]] to surface {{math|Σ}}. (Vector area is sometimes denoted by {{mat spatial metric independent of time ...

...], geometry in accelerated, noninertial reference frames. Employing the [[metric tensor]] which describes [[Minkowski space]]: ...tered by the presence of [[gravitational fields]] (see the [[Schwarzschild metric]]): ...