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EHB star setâre-ye EHB Fr.: étoile EBH Same as → extreme horizontal branch star. |
eigenfunction viž-karyâ Fr.: fonction propre 1) Math.: An → eigenvector for a linear
→ operator on a → vector space
whose vectors are → functions. Also known as
proper function. From Ger. Eigenfunktion, from eigen- "characteristic, particular, own" (from P.Gmc. *aigana- "possessed, owned," Du. eigen, O.E. agen "one's own") + → function. Viž-karyâ, from viž, contraction of vižé "particular, charcteristic" + karyâ, → function. Vižé, from Mid.Pers. apēcak "pure, sacred," from *apa-vēcak "set apart," from prefix apa- + vēcak, from vēxtan (Mod.Pers. bixtan) "to detach, separate, sift, remove," Av. vaēk- "to select, sort out, sift," pr. vaēca-, Skt. vic-, vinakti "to sift, winnow, separate; to inquire." |
eigenstate viž-hâlat Fr.: état propre Quantum mechanics: A dynamical state whose state vector (or wave function) is an → eigenvector of an → operator corresponding to a specified physical quantity. → eigenfunction; → state. |
eigenvalue viž-arzé Fr.: valeur propre 1) Math.: The one of the → scalars λ such
that T(v) = λv, where T is a linear → operator
on a → vector space, and v is an
→ eigenvector. → eigenfunction; → value. |
eigenvector viž-bordâr Fr.: vecteur propre Math.: A nonzero vector v whose direction is not changed by a given linear transformation T; that is, T(v) = λ v for some scalar λ. → eigenfunction; → vector. |
eight hašt (#) Fr.: huit A → cardinal number between → seven and → nine. M.E. eighte, from O.E. eahta, æhta, related to O.Norse atta, Swed. åtta, Du. acht, O.H.G. Ahto, Ger. acht; Pars. hašt, as below, from PIE *okto(u) "eight." Hašt, from Mid.Pers. hašt; Av. ašta; cognate with Skt. asta; Gk. okto; L. octo (from which It. otto, Sp. ocho, Fr. huit). |
einstein einstein (#) Fr.: einstein A unit of radiation energy sometimes used in the investigation of photochemical processes. The unit is defined as N_{A}hν, where N_{A} is → Avogadro's number and hν is the energy of a → quantum of the radiation. One einstein (or Einstein unit) is the energy per → mole of photons carried by a beam of monochromatic light. Named for Albert Einstein (1879-1955). |
Einstein coefficient hamgar-e Einstein Fr.: coefficient d'Einstein A measure of the probability that a particular atomic transition leading to the formation of an atomic spectral line occurs. The coefficient of spontaneous emission is denoted by A_{ij}, and the coefficient of stimulated emission by B_{ij}, i representing the lower level and j is the upper level. Named after Albert Einstein (1879-1955) who introduced the coefficients in 1916; → coefficient. |
Einstein cross calipâ-ye Einstein Fr.: croix d'Einstein An image of a distant quasar (redshift 1.7) formed by a foreground spiral galaxy (redshift 0.039) through gravitational lensing. The image of the quasar is split into four point sources forming a cross at the center of the galaxy. |
Einstein equivalence principle parvaz-e hamug-arzi-ye Einstein Fr.: principe d'équivalence d'Einstein The → equivalence principle as stated by Einstein, on which is
based the theory of → general relativity. It comprises
the three following items: → Einstein; → equivalence; → principle. |
Einstein model model-e Einstein Fr.: modèle d'Einstein A model for the → specific heat of solids in which the specific heat is due to the vibrations of the atoms of the solids. The vibration energy is → quantized and the atoms have a single frequency, ν. Put forward in 1907 by Einstein, this model was the first application of → quantum theory to the solid state physics. The expression for the specific heat is given by: C_{V} = 3Rx^{2}e^{x}/(e^{x} -1)^{2}, where R is the → gas constant, x = T_{E}/T, T_{E} = hν/k, h is → Planck's constant, and k is → Boltzmann's constant. T_{E} is called the → Einstein temperature. This model could explain the temperature behavior of specific heat but not very satisfactorily at low temperatures. It has therefore been superseded by the → Debye model. See also → Dulong-Petit law. Albert Einstein in 1907; → model. |
Einstein notation namâdgân-e Einstein Fr.: convention Einstein A notation convention in → tensor analysis whereby whenever there is an expression with a repeated → index, the summation is done over that index from 1 to 3 (or from 1 to n, where n is the space dimension). For example, the dot product of vectors a and b is usually written as: a.b = Σ (i = 1 to 3) a_{i}.b_{i}. In the Einstein notation this is simply written as a.b = a_{i}.b_{i}. This notation makes operations much easier. Same as Einstein summation convention. |
Einstein solid model-e Einstein Fr.: modèle d'Einstein Same as → Einstein model. |
Einstein static Universe 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 temperature damâ-ye Einstein (#) Fr.: température d'Einstein A characteristic parameter occurring in the → Einstein model of → specific heats. → Einstein; → temperature. |
Einstein tensor 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 G_{μν} = R_{μν} - (1/2) g_{μν}R, where R_{μν} is the Ricci tensor, g_{μν} 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's elevator 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 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: G_{μν} = -κ T_{μν}, where G_{μν} is the → Einstein tensor (a function of the → metric tensor), κ is a coupling constant called the → Einstein gravitational constant, and T_{μν} 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: G_{μν} + Λg_{μν} = - κT_{μν}, where Λ is the → cosmological constant. Named after Albert Einstein (1879-1955); → field; → equation. |
Einstein's gravitational constant pâyâ-ye gerâneši-ye Einstein (#) Fr.: constante gravitationnelle d'Einstein The coupling constant appearing in → Einstein's field equations, expressed by: κ = 8πG/c^{4}, where G is the Newtonian → gravitational constant and c the → speed of light. → einstein; → gravitational; → constant. |
Einstein's theory of specific heat negare-ye garmâ-ye âbize-ye Einstein Fr.: théorie de la chaleur spécifique d'Einstein Same as → Einstein model. → Einstein; → theory; → specific heat. |
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