# 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: 13 Search : cosmological
 anisotropic homogeneous cosmological model   مدل ِ کیهانشناختی ِ همگن و نا-ایزوگرد   model-e keyhânšenâxti-ye hamgen o nâ-izogardFr.: modèle cosmiologique homogène mais anisotrope   A solution to Einstein's theory of → general relativity that is spatially homogeneous but allows for rotation and/or shear. See also → Bianchi cosmological model.→ anisotropic; → homogeneous; → cosmological; → model. Bianchi cosmological model   مدل ِ کیهانشناختی ِ بیانکی   model-e keyhânšenâxti-ye BianchiFr.: modèle cosmologique de Bianchi   A cosmological model based on the theory of → general relativity, which is homogeneous but → anisotropic. There are actually ten dinstinct Bianchi types, classified according to the particular kinds of symmetry they posses.Luigi Bianchi (1856-1928), Italian mathematician; → cosmological; → model. cosmological   کیهان‌شناختی، کیهان‌شناسیک   keyhânšenâxti, keyhânšenâsikFr.: cosmologique   Pertaining or relating to → cosmology.→ cosmology; → -al. cosmological constant   پایای ِ کیهان‌شناسیک، ~ کیهان‌شناختی   pâyâ-ye keyhânšenâsik, ~ keyhânšenâxtiFr.: constante cosmologique   A term introduced by Einstein into his gravitational → field equations in order to allow a solution corresponding to a → static Universe. The cosmological constant is physically interpreted as due to the → vacuum energy of quantized fields. See also → dark energy.→ cosmological; → constant. cosmological constant problem   پراسه‌ی ِ پایای ِ کیهانشناختی   parâse-ye pâyâ-ye keyhânšenâxtiFr.: problème de la constante cosmologique   The impressive discrepancy of about 120 orders of magnitude between the theoretical value of the → cosmological constant and its observed value. → Quantum field theory interprets the cosmological constant as the density of the → vacuum energy. This density can be derived from the maximum energy at which the theory is valid, i.e. the → Planck energy scale (1018 GeV). The theoretical vacuum → energy density is (1018 GeV)4 = (1027 eV)4 = 10112 erg cm-3. On the other hand, the observed vacuum energy density is estimated to be about (10-3 eV)4 = 10-8 erg cm-3. There is, therefore, a discrepancy of about 120 orders of magnitude.→ cosmological; → constant; → problem. cosmological distance   دورای ِ کیهان‌شناسیک، ~ کیهان‌شناختی   durâ-ye keyhânšenâsik, ~ keyhânšenâxtiFr.: distance cosmologique   The distance to a remote galaxy based on its redshift assuming that the redshift is caused by the → Doppler effect and reflects the general expansion of the Universe.→ cosmological; → distance . cosmological epoch   زیمه‌ی ِ کیهانشناختی   zime-ye keyhânšenâxtiFr.: époque cosmologique   → cosmological; → epoch. cosmological model   مدل ِ کیهان‌شناسیک، ~ کیهان‌شناختی   model-e keyhânšenâsik, ~ keyhânšenâxtiFr.: modèle cosmologique   A mathematical description of the Universe, based on observation, which tries to explain its current aspect, and to describe its evolution during time.→ cosmological; → model. cosmological principle   پروز ِ کیهان‌شناسیک، ~ کیهان‌شناختی   parvaz-e keyhânšenâsik, ~ keyhânšenâxtiFr.: principe cosmologique   The → hypothesis that on → large scales the → Universe is → isotropic and → homogeneous, that is, it appears the same at all places and, from any one place, looks the same in all directions. See also → perfect cosmological principle.Introduced by E.A. Milne in 1933; → cosmological; → principle. cosmological redshift   سرخ کیب ِ کیهان‌شناسیک، ~ کیهان‌شناختی   sorxkib-e keyhânšenâsik, ~ keyhânšenâxtiFr.: décalage vers le rouge cosmologique, redshift ~   The → redshift of a remote object (galaxy, quasar, supenova) due to the expansion of the Universe.→ cosmological; → redshift. current cosmological epoch   زیمه‌ی ِ کیهانشناختی ِ کنونی   zime-ye keyhânšenâxti-ye konuniFr.: époque cosmologique actuelle   The → Universe at the → redshift z = 0.→ current; → cosmological; → epoch. Milne cosmological model   مدل ِ کیهان‌شناختی ِ میلن   model-e keyhânšenâxti-ye Milne (#)Fr.: modèle cosmologique de Milne   Same as → Milne Universe.→ Milne Universe; → cosmological; → model. perfect cosmological principle   پروز ِ کیهان‌شناسیک ِ فرساخت   parvaz-e keyhânšenâsik-e farsâxtFr.: principe cosmologique parfait   The → assumption, adopted by the → steady-state theory, that all observers, everywhere at all times, would view the same large-scale distribution of matter in the → Universe in all regions and in every direction. In contrast to the → cosmological principle, the perfect cosmological principle adds the assumption that the Universe does not change with time on the large scale.→ perfect; → cosmological; → principle.