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

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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 gauge invariance   ناورتایی ِ گز   nâvartâyi-ye gazFr.: invariance de jauge   The invariance of any field theory under gauge transformation.→ gauge; → invariance. gauge symmetry   همامونی ِ گز   hamâmuni-ye gazFr.: symétrie de jauge   A principle underlying the quantum-mechanical description of the three non-gravitational forces. It allows a system to behave in the same way even though it has undergone various transformations. The earliest physical theory which had a gauge symmetry was Maxwell's electrodynamics.→ gauge; → symmetry. gauge theory   نگره‌ی ِ گز   negare-ye gaz (#)Fr.: théorie de jauge   A field theory in which it is possible to perform a transformation without altering any measurable physical quantity.→ gauge; → theory. gauge transformation   ترادیس ِ گز   tarâdis-e gaz (#)Fr.: transformation de jauge   A change of the fields of a gauge theory that does not change the value of any measurable quantity.→ gauge; → transformation. gauging   گزکرد   gazkardFr.:   A technique in which the thickness, density, or quantity of a material is determined by the amount of radiation it absorbs.Gauging, from → gauge + → -ing, suffix of nouns formed from verbs, expressing the action of the verb or its result.Gazkard, from gaz, → gauge, + kard past stem of kardan "to do, make," → gauge. Gaunt factor   کروند ِ گاؤنت   karvand-e GauntFr.: facteur de Gaunt   In the atomic theory of spectral line formation, a quantum mechanical correction factor applied to the absorption coefficient in the transition of an electron from a bound or free state to a free state.Gaunt, after John Arthur Gaunt (1904-1944), English physicist born in China, who significantly contributed to the calculation of continuous absorption using quantum mechanics; → factor gauss   گاؤس   gauss (#)Fr.: gauss   The c.s.g. unit of magnetic flux density (or magnetic induction), equal to 1 maxwell per square centimeter, or 10-4 tesla.Named after the German mathematician and physicist Carl Friedrich Gauss (1777-1855). Gauss's law for electricity   قانون ِ گاؤس در برق   qânun-e Gauss dar barqFr.: loi de Gauss en électricité   The total electric flux ψ out of an arbitrary closed surface in free space is equal to the net charge within the surface divided by the → permittivity. In differential form: ∇ . E = ρ/ε0, where ρ is the → charge density and ε0 the permittivity. The integral form of the law: ∫E . dS = Q/ε0 (closed surface integral). This is one of the four → Maxwell's equations.→ gauss; → law; → electricity. Gauss's law for magnetism   قانون ِ گاؤس در مغنات‌مندی   qânun-e Gauss dar meqnâtmandiFr.: loi de Gauss en magnétisme   The → magnetic flux through an arbitrary closed surface equals zero. Mathematically, in differential form: ∇ . B = 0 and in integral form: ΦB = ∫B.dS = 0 (closed surface integral). This is one of the four → Maxwell's equations. This law expresses the fact that there are no free magnetic poles (→ monopoles) in nature and that all the lines of force of a magnetic field are closed curves.→ gauss; → law; → magnetism. Gauss's lemma   نهک ِ گاؤس   nehak-e GaussFr.: lemme de Gauss   If a → polynomial with → integer coefficients can be → factorized into polynomials with → rational number coefficients, it can be factorized using only integers.→ Gaussian; → lemma. Gauss's theorem   فربین ِ گاؤس   farbin-e GaussFr.: théorème de Gauss   The total normal induction over any closed surface drawn in an electric field is equal to 4π times the total charge of electricity inside the closed surface. Gauss's theorem applies also to other vector fields such as magnetic, gravitational, and fluid velocity fields. The theorem can more generally be stated as: the total flux of a vector field through a closed surface is equal to the volume → integral of the vector taken over the enclosed volume. Also known as → divergence theorem, Ostrogradsky's theorem, and Gauss-Ostrogradsky theorem.→ gauss; → theorem. Gaussian   گاؤسی   Gaussi (#)Fr.: gaussien   Of or relating to Carl Friedrich Gauss or his mathematical theories of magnetism, electricity, astronomy, or probability. → Gaussian distribution; → Gaussian profile.→ gauss. Gaussian distribution   واباژش ِ گاؤسی   vâbâžeš-e Gaussi (#)Fr.: distribution gaussienne   A theoretical frequency distribution for a set of variable data, usually represented by a bell-shaped curve with a mean at the center of the curve and tail widths proportional to the standard deviation of the data about the mean.→ Gaussian; → distribution. Gaussian elimination   اسانش ِ گاؤسی   osâneš-e GaussiFr.: élimination de Gauss   A method of solving a matrix equation of the form A x = b, where A is a matrix and x and b are vectors. The process consists of two steps, first reducing the elements below the diagonal to 0 and second, back substituting to find the solutions.→ Gaussian; → elimination. Gaussian function   کریای ِ گاؤس   karyâ-ye GaussFr.: fonction de Gauss   The function e-x2, whose integral in the interval -∞ to +∞ gives the → square root of the → number pi: ∫e-x2dx = √π. It is the function that describes the → normal distribution.→ Gaussian; → function. Gaussian gravitational constant   پایای ِ گرانشی ِ گاؤس   pâyâ-ye gerâneši-ye GaussFr.: constante gravitationnelle de Gauss   The constant, denoted k, defining the astronomical system of units of length (→ astronomical unit), mass (→ solar mass), and time (→ day), by means of → Kepler's third law. The dimensions of k2 are those of Newton's constant of gravitation: L 3M -1T -2. Its value is: k = 0.01720209895.→ Gaussian; → gravitational; → constant. Gaussian integer   درسته‌ی ِ گاؤس   doroste-ye GaussFr.: entier de Gauss   A → complex number whose → real and → imaginary parts are both integers.→ Gaussian; → integer. Gaussian profile   فراپال ِ گاؤسی   farâpâl-e GaussiFr.: profile gaussien   The shape of a curve representing a normal distribution.→ Gaussian; → profile. Gaussianity   گاؤسیگی   GaussigiFr.: gaussienité   Math.: The condition of having → Gaussian distribution. The extent to which something is Gaussian.→ Gaussian + → -ity. Gay-Lussac's law   قانون ِ گی-لوساک   qânun-e Gay-Lussac (#)Fr.: loi de Gay-Lussac   1) Law of combining volumes. The volumes of gases used and produced in a chemical reaction, are in the ratio of small whole numbers when measured at constant temperature and pressure. 2) For a gas held at constant volume, there is a direct correlation between temperature and pressure: P1/T1 = P2/T2. Gay-Lussac's law, → Boyle-Mariotte law, and → Charles' law were later unified into the → ideal gas law.Named after Joseph Louis Gay-Lussac (1778-1850), a French chemist and physicist; → law.