An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 696
Einstein ring
  حلقه‌ی ِ اینشتین   
halqe-ye Einstein

Fr.: anneau d'Einstein   

The apparent shape of a background source unsergoing the effect of → gravitational lensing as seen from Earth, provided that the source, the intervening lens, and the observer are in perfect alignement through → Einstein radius.

Einstein; → ring.

Einstein solid
  مدل ِ اینشتین   
model-e Einstein

Fr.: modèle d'Einstein   

Same as → Einstein model.

Einstein; → solid.

Einstein static Universe
  گیتی ِ ایستای ِ اینشتین   
giti-ye istâ-ye Einstein

Fr.: Univers stationnaire d'Einstein   

A cosmological model in which a static (neither expanding nor collapsing) Universe is maintained by introducing a cosmological repulsion force (in the form of the cosmological constant) to counterbalance the gravitational force.

Einstein; → static; arr; universe.

Einstein temperature
  دمای ِ اینشتین   
damâ-ye Einstein (#)

Fr.: température d'Einstein   

A characteristic parameter occurring in the → Einstein model of → specific heats.

Einstein; → temperature.

Einstein tensor
  تانسور ِ اینشتین   
tânsor-e Einstein (#)

Fr.: tenseur d'Einstein   

A mathematical entity describing the → curvature of → space-time in → Einstein's field equations, according to the theory of → general relativity. It is expressed by Gμν = Rμν - (1/2) gμνR, where Rμν is the Ricci tensor, gμν is the → metric tensor, and R the scalar curvature. This tensor is both symmetric and divergence free.

Named after Albert Einstein (1879-1955); → tensor.

Einstein time-scale
  مرپل ِ زمانی ِ اینشتین   
marpel-e zamâni-ye Einstein

Fr.: échelle de temps d'Einstein   

The time during which a → microlensing event occurs. It is given by the equation tE = RE/v, where RE is the → Einstein radius, v is the magnitude of the relative transverse velocity between source and lens projected onto the lens plane. The characteristic time-scale of → microlensing events is about 25 days.

Einstein; → time-scale.

Einstein's elevator
  بالابر ِ اینشتین   
bâlâbar-e Einstein

Fr.: ascenseur d'Einstein   

A → thought experiment, involving an elevator, first conceived by Einstein to show the → principle of equivalence. According to this experiment, it is impossible for an observer situated inside a closed elevator to decide if the elevator is being pulled upward by a constant force or is subject to a gravitational field acting downward on a stationary elevator. Einstein used this experiment and the principle of equivalence to deduce the bending of light by the force of gravity.

einstein; elevator, from L. elevator, agent noun from p.p. stem of elevare "to lift up, raise," from → ex- "out" + levare "lighten, raise," from levis "light" in weight, → lever.

Bâlâbar, → lift.

Einstein's field equations
  هموگش‌های ِ میدان ِ اینشتین   
hamugešhâ-ye meydân-e Einstein

Fr.: équations de champ d'Einstein   

A system of ten non-linear → partial differential equations in the theory of → general relativity which relate the curvature of → space-time with the distribution of matter-energy. They have the form: Gμν = -κ Tμν, where Gμν is the → Einstein tensor (a function of the → metric tensor), κ is a coupling constant called the → Einstein gravitational constant, and Tμν is the → energy-momentum tensor. The field equations mean that the curvature of space-time is due to the distribution of mass-energy in space. A more general form of the field equations proposed by Einstein is: Gμν + Λgμν = - κTμν, where Λ is the → cosmological constant.

Named after Albert Einstein (1879-1955); → field; → equation.

Einstein's gravitational constant
  پایای ِ گرانشی ِ اینشتین   
pâyâ-ye gerâneši-ye Einstein (#)

Fr.: constante gravitationnelle d'Einstein   

The coupling constant appearing in → Einstein's field equations, expressed by: κ = 8πG/c4, where G is the Newtonian → gravitational constant and c the → speed of light.

einstein; → gravitational; → constant.

Einstein's theory of specific heat
  نگره‌ی ِ گرمای ِ آبیزه‌ی ِ اینشتین   
negare-ye garmâ-ye âbize-ye Einstein

Fr.: théorie de la chaleur spécifique d'Einstein   

Same as → Einstein model.

Einstein; → theory; → specific heat.

Einstein-de Sitter effect
  اسکر ِ اینشتین-دو سیتر   
oskar-e Einstein-de Sitter

Fr.: effet Einstein-de Sitter   

Same as → geodetic precession.

Einstein-de Sitter Universe; → effect.

Einstein-de Sitter Universe
  گیتی ِ اینشتین-دو سیتر   
giti-ye Einstein-de Sitter

Fr.: Univers Einstein-de Sitter   

The → Friedmann-Lemaitre model of → expanding Universe that only contains matter and in which space is → EuclideanM > 0, ΩR = 0, ΩΛ = 0, k = 0). The Universe will expand at a decreasing rate for ever.

Einstein; de Sitter, after the Dutch mathematician and physicist Willem de Sitter (1872-1934) who worked out the model in 1917; → Universe.

Einstein-Hilbert action
  ژیرش ِ اینشتین-هیلبرت   
žireš-e Einstein-Hilbert

Fr.: action de Einstein-Hilbert   

In → general relativity, the → action that yields → Einstein's field equations. It is expressed by:
SEH = (1/2κ)∫d4x (-g)1/2R + Sm,
where κ ≡ 8πG and Sm is the matter part of the action.

Einstein; → Hilbert space; → action.

Einstein-Podolsky-Rosen paradox
  پارادخش ِ اینشتین-پودولسکی-روزن   
pârâdaxš-e Einstein-Podolsky-Rosen

Fr.: paradoxe Einstein-Podolsky-Rosen   

EPR paradox.

A. Einstein, B. Podolsky, N. Rosen: "Can quantum-mechanical description of physical reality be considered complete?" Phys. Rev. 41, 777 (15 May 1935); → paradox.

Einstein-Rosen bridge
  پل ِ اینشتین-روزن   
pol-e Einstein-Rosen

Fr.: pont d'Einstein-Rosen   

A hypothetical structure that can join two distant regions of → space-time through a tunnel-like shortcut, as predicted by → general relativity. The Einstein-Rosen bridge is based on the → Schwarzschild solution of → Einstein's field equations. It is the simplest type of → wormholes.

Albert Einstein & Nathan Rosen (1935, Phys.Rev. 48, 73); → bridge.

Einsteinian relativity
  بازانیگی ِ اینشتینی   
bâzânigi-ye Einsteini

Fr.: relativité einsteinienne   

The laws of physics are the same in all → inertial reference frames and are invariant under the → Lorentz transformation. The → speed of light is a → physical constant, i.e. it is the same for all observers in uniform motion. Einsteinian relativity is prompted by the → Newton-Maxwell incompatibility. See also: → Galilean relativity, → Newtonian relativity.

Einstein; → relativity.

einsteinium (#)

Fr.: einsteinium   

A radioactive metallic → transuranium element belonging to the → actinides; symbol Es. → Atomic number 99, → mass number of most stable → isotope 254 (→ half-life 270 days). Eleven isotopes are known. The element was first identified by A. Ghiorso and collaborators in the debris of first hydrogen bomb explosion in 1952.

Named after Albert Einstein, → einstein + → -ium.


Fr.: éjecter   

To throw out material, for example by a massive star through stellar wind, or by a volcano in eruption.

From L. ejectus, p.p. of eicere "to throw out," from → ex- "out" + -icere, comb. form of jacere "to throw."

Ešândan, from Hamadâni ešândan "to throw out;" Pashto aestal, wištal "to throw, project;" Laki owštan "to throw, to shoot (with bow and arrow);" Lori šane "throwing," šane kerde "to throw;" Av. ah- "to throw," pres. ahya- "throws," asta- "thrown, shot," astar- "thrower, shooter;" cf. Khotanese ah- "to throw, shoot," Skt. as- "to throw, shoot," ásyati "throws," ásana- "throw, shot."


Fr.: éjecta   

Material, in solid, liquid, or gaseous form, thrown out by a body, especially as a result of → volcanic eruption, → meteoritic impact, or → supernova explosion. See also: → ejecta blanket, → supernova ejecta.

Plural of L. ejectus, → eject.

Ešânâk "that which is ejected," from šân present stem of šândaneject + suffix -âk.

ejecta blanket
  پتو‌ی ِ اشاناک   
patu-ye ešânâk

Fr.: couverture d'éjecta   

Of an → impact crater, the ejecta that after the → impact event settles back to the Earth's surface. The ejecta blanket is thick near the → crater rim and thin outward from the crater.

ejecta; → blanket.

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