# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 6 Search : contraction
 contraction   ترنگش   terengešFr.: contraction   An act or instance of contracting; the quality or state of being contracted. → gravitational contraction, → Kelvin-Helmholtz contraction, → length contraction, → Lorentz contraction.Verbal noun of → contract. gravitational contraction   ترنگش ِ گرانشی   terengeš-e gerânešiFr.: contraction gravitationnelle   Decrease in the volume of an astronomical object under the action of a dominant, central gravitational force. Kelvin-Helmholtz contraction   ترنگش ِ کلوین-هلمهولتس   terengeš-e Kelvin-HelmholtzFr.: contraction de Kelvin-Helmholtz   The contraction of a volume of gas under its → gravity, accompanied by the → radiation of the lost → potential energy as → heat.After the Scottish physicist William Thomson, also known as Lord Kelvin (1824-1907) and the German physicist and physician Hermann Ludwig Ferdinand von Helmholtz (1821-1894), who made important contributions to the thermodynamics of gaseous systems; → contraction. length contraction   ترنگش ِ درازا   terengeš-e derâzâFr.: contraction de longueur   Same as → Lorentz contraction.→ length; → contraction. Lorentz contraction   ترنگش ِ لورنتز   terengeš-e LorentzFr.: contraction de Lorentz   The decrease in the length of a body moving in the direction of its length as measured by an observer situated in that direction. The shortening factor is [1 - (v/c)2]1/2, where v is the relative velocity and c light speed.→ Lorentz; → contraction. tensor contraction   ترنگش ِ تانسور   terengeš-e tânsorFr.: contraction de tenseur   An operation of tensor algebra that is obtained by setting unlike indices equal and summing according to a summation convention.→ contraction; → tensor.