An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 12955 Search : far
cosmological constant problem
  پراسه‌ی ِ پایای ِ کیهانشناختی   
parâse-ye pâyâ-ye keyhânšenâxti

Fr.: 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, ~ keyhânšenâxti

Fr.: 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 keyhânšenâxti

Fr.: époque cosmologique   

cosmological; → epoch.

cosmological model
  مدل ِ کیهان‌شناسیک، ~ کیهان‌شناختی   
model-e keyhânšenâsik, ~ keyhânšenâxti

Fr.: 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, ~ keyhânšenâxti

Fr.: 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, ~ keyhânšenâxti

Fr.: décalage vers le rouge cosmologique, redshift ~   

The → redshift of a remote object (galaxy, quasar, supenova) due to the expansion of the Universe.

cosmological; → redshift.

cosmology
  کیهان‌شناسی   
keyhânšenâsi (#)

Fr.: cosmologie   

The science of the origin, structure, and evolution of the Universe including the origin of galaxies, the chemical elements, and matter.

Cosmology, from → cosmo- + → -logy.

Keyhânšenâsi, from keyhân, → cosmos, + šenâsi, → -logy.

cosmonaut
  کیهان نورد، فضا نورد   
keyhânnavard (#), fazânavard (#)

Fr.: cosmonaute, astronaute   

The Russian term for → astronaut.

Cosmonaut, from → cosmo- + naute, from Gk. nautes "sailor," from naus "ship" (cognate with Pers. nâv "ship," Av./O.Pers. *nāv-, O.Pers. nāviyā- "fleet," Skt. nau-, nava- "ship, boat," Gk. naus, neus, L. navis; PIE *nâu- "ship").

cosmos
  کیهان   
keyhân (#)

Fr.: cosmos   

Everything that exists anywhere; → outer space; → Universe.

M.E., from Gk. kosmos "orderly arrangement."

Keyhân "world," variants geyhân, jahân, giti "world, material world, time," Mid.Pers. gêhân, gêtig, Manichean Mid.Pers. gyh "world," Av. gaeθa- "being, world, matter, mankind", gaya- "life, manner of living," root gay- "to live" (present tense jiva-), O.Pers. gaiθā- "live-stock," cognate with Skt. jivah "alive, living," Gk. bios "life," L. vivus "living, alive," vita "life;" PIE base *gweie- "to live" (cf. O.E. cwic, "alive;" O.C.S. zivo "to live;" Lith. gyvas "living, alive;" O.Ir. bethu "life," bith "age;" Welsh byd "world"). The Persian terms zistan "to live," zendé "alive," zendegi "life," and jân "vital spirit, soul" belong to this family.

cotangent
  کوتانژانت   
kotânžânt (#)

Fr.: cotangent   

The → tangent of the complement of an arc or angle; abbreviation cot. If θ is an → acute angle of a → right angle, cot θ = (adjacent side)/(opposite side).

co-; → tangent.

cotton
  پنبه   
panbé (#)

Fr.: coton   

A soft, usually white fibrous substance like fine wool surrounding the seeds of various tropical and subtropical plants of the mallow family. It is extensively used in making threads, yarns, and fabrics.

M.E. coton, from O.Fr. coton, from O.It. cotone, from Ar. qutn (قطن), perhaps of Egyptian origin.

Panbé "cotton" (dialectal Lori pamma, Kurd. pemû, maybe Tajik, Afqân pakta, pakhta, bakhta, bakta), from Mid.Pers. pambag "cotton," pambagin "made of cotton," perhaps loaned in Gk. bombux "silk, any silk-like fine fiber;" L. bombyx "silk, cotton," L.L. bombax "cotton," hence O.Fr. bombace "cotton, cotton wadding," E. bombast "cotton wool; inflated language."

coudé focus
  کانون ِ آرنج‌وار   
kânun-e ârenjvâr, ~ kudé

Fr.: foyer coudé   

An → optical system in which the → beam of light from the → primary mirror is reflected down through the instrument's → polar axis by a path bent like an → elbow. Since the focus remains fixed with respect to the Earth, light can be analyzed with permanently installed instruments. In addition long → focal lengths allow higher → spectral dispersions.

From Fr. coudé "elbowed," from coude "elbow," L. cubitus; → focus.

Kânun, → focus; ârenjvâr "elbow-like," → elbow.

Couette flow
  تچان ِ کویءت   
tacân-e Couette

Fr.: écoulement de Couette   

In fluid dynamics, the motion of an → incompressible → laminar flow passing between two parallel plates, when the upper plate is moving with some velocity while the lower one is stationary. The flow is driven owing to the fluid → viscosity and the applied pressure gradient parallel to the plates. See also → Taylor-Couette flow.

Named after Maurice Marie Alfred Couette (1858-1943), a French physicist who dealt mainly with fluid mechanics; → flow

Couette viscometer
  وشک‌سنج ِ کویءت   
vošksanj-e Couette

Fr.: viscosimètre de Couette   

A device consisting of two vertical coaxial cylinders and a fluid filling the volume between the cylinders and used for measuring the viscosity of the fluid. The inner cylinder is stationary while the outer cylinder rotates. The amount of shear stress produced owing to rotation is directly proportional to the viscosity of the fluid.

Couette flow; → viscometer.

Couette-Taylor flow
  تچان ِ کویءت-تیلر   
tacân-e Couette-Taylor

Fr.: écoulement de Couette-Taylor   

In fluid mechanics, the motion of a fluid between two concentric cylinders when one or both of the cylinders rotate.

Couette flow; Geoffrey Ingram Taylor (1886-1975), British physicist; → flow.

coulomb (C)
  کولن   
coulomb (#)

Fr.: coulomb   

The unit of → electric charge in the → mks system, equal to the quantity of charge transferred in one second by a steady current of one → ampere. One coulomb represents a charge of approximately 6.241 506 × 1018 → electrons. Compared with the charge unit in the → cgs system, 1 C = 2.998 × 109 → esu.

Named after the French physicist Charles Augustin de Coulomb (1736-1806), who pioneered research into magnetism and electricity.

Coulomb barrier
  ورغه‌ی ِ کولن   
varqe-ye Coulomb (#)

Fr.: barrière de Coulomb   

The energy barrier due to electrostatic interaction that two nuclei (for example two protons) need to overcome so they can get close enough to undergo nuclear fusion (to form a helium).

coulomb; → barrier.

Coulomb collision
  همکوبش ِ کولن   
hamkubeš-e Coulomb

Fr.: collision coulombienne   

A particle → collision where the dominant force is described by → Coulomb's law. The collision results in deflections of the particles away from their initial paths.

coulomb; → collision.

Coulomb energy
  کاروژ ِ کولن   
kâruž-e Coulomb

Fr.: énergie coulombienne   

The → potential energy from which derives the repulsive electrostatic force between two → charged particles. For example, the Coulomb energy between two protons is e2/r ~ 0.5 MeV, which is small compared with the average → binding energy per particle (~ 8 Mev). However the Coulomb repulsion becomes important for heavy nuclei. The total Coulomb energy of a nucleus is given by: (3/5) Z(Z - 1)e2/R, where Z is the → atomic number, e the charge, and R the nuclear radius. Since R ∝ A1/3 and Z is roughly proportional to A, the Coulomb energy is roughly proportional to A5/3. On the other hand, the total binding energy is proportional to A, which means that the relative importance of the repulsive electrostatic energy increases with increasing mass number as A2/3.

coulomb; → energy.

Coulomb excitation
  بر‌انگیزش ِ کولن   
barangizeš-e Coulomb

Fr.: excitation coulombienne   

The transition to a higher → energy level than → ground state undergone by an atomic nucleus when a → charged particle of appropriate energy moves past it.

coulomb; → excitation.

<< < -es -iv -ti 21- A r abe abs abs acc acc acc act act ada adi adu aff age alc Alf ali all alp alt ama amp ana ang ang ann ano ant ant ape apo app aps arc Arg ari art ass ast ast ast atm ato att aur aut axi B r bac Bal Bar Bar Bay bec Ber Bet Bie bij bin bio bis bla bla blu blu bol Bor bou Bra bre bro Bug C-s cal Cam can car Car Cas cat cav cel cen cer Cha cha cha che cho cir cir cir cla clo clo clu coa coe coh col col col com com com com com com com com com con con con con con con con con con con con coo cor cor cor cos cos cos Cou cou Cra Cre cri cro cub cur cyc cyl dar dat daw de- Deb dec dec dee def deg del Den dep der det deu dew dic dif dif dil dip dir dis dis dis dis dis diu dog Dop dou Dra dua dus dwa dyn e-f Ear ecl eco edu eig Ein ela ele ele ele Ele elo emi emp ene Enl env epi equ equ Eri est Euc eva evo exc exc exh Exo exp exp ext ext f(R fac fam fat fee Fer Fib fig fin fir fix fle flu foc for for for fra fre Fre fri fun fuz Gal gal gal Gam gau Gay gen Geo geo geo geo gim glo gov gra gra gra gra gre gro Gun hab hal han Har haz hea hel hel Hen Her het Hig hil hol Hoo hor hou Hub hum hyd hyd hyd hyp hys ide ign ima imp imp inc inc ind Ind inf inf inf inf inn ins ins int int int int int int int int inv ion ion Irr iso iso iso jan jit Jul jus Kel ker kin kni La lam lan Lap las lat Lay Led Len let lif lig lin lin lin liq Lit loc log lon lou low lum lun Lym M d Mag mag mag mag mag mag maj man mar mas mas mat mea mea mec mem mer Mes met met mho mic Mie Mil min mis MKS MOd mol Mon moo mot mul mul myo nak Nas nat neb neg neu neu New New nit noi non non nor nor nuc nuc nul nut obj obl obs occ oct off oli oni ope opp opt opt orb ord org orp osc out ove oxi pai Pan par par Par par pas Pav Pel per per per per Per per pha phi pho pho pho phy Pip Pla pla PLA pla ple plu pol pol pol pol pop pos pos pot Pra pre pre pre Pri pri pri pro pro pro pro pro pro pro Pto pul pur qua qua qua qua qui rad rad rad rad rad rad rai ran rar Ray rea rea rec rec red red ref ref reg rel rel rel rep res res res res ret RHB rid rig ris roc Ros rot rub Rut Sag sam sat sca sca Sch sci Sea sec sec see sel sem sen set Sha sha shi shu sid sil sim sin SIS ski Slo smo Soc sol sol sol sol son sou spa spa spe spe spe sph spi spi Spo squ sta sta sta sta Ste ste ste sto str str str sub sub suc sun sup sup sup sup sur Swa syn syn tab tar tel tem ter tes the the the the Tho thr tid tim Tit top tot tra tra TRA tra tre tri tri tru Tun Tus tym Typ ult unb und uni uni uns upp Urs vac van var Vei Ven ver vic Vir vir vis vol W 4 war wat wav wea wed wet wid win WN2 Wol wri xen yok zen zin > >>