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conformal compactification hampakâneš-e hamdi Fr.: compactification conforme A mapping of an infinite → space-time onto a finite one that may make the far away parts of the former accessible to study. The technique invented by Penrose defines an equivalence class of → metrics, g_{ab} being equivalent to ĝ_{ab} = Ω^{2}g_{ab}, where Ω is a positive scalar function of the space-time that modifies the distance scale making the asymptotics of the physical metric accessible to study. → conformal; → compactification. |
conformal cyclic cosmology (CCC) keyhânšenâsi-ye carxe-yi-ye hamdis Fr.: cosmologie cyclique conforme A cosmological model developped by Roger Penrose and colleagues according which the Universe undergoes repeated cycles of expansion. Each cycle, referred to an aeon, starts from its own "→ big bang" and finally comes to a stage of accelerated expansion which continues indefinitely. There is no stage of contraction (to a "→ big crunch") in this model. Instead, each aeon of the universe, in a sense "forgets" how big it is, both at its big bang and in its very remote future where it becomes physically identical with the big bang of the next aeon, despite there being an infinite scale change involved, on passing from one aeon to the next. This model considers a conformal structure rather than a metric structure. Conformal structure may be viewed as family of metrics that are equivalent to one another via a scale change, which may vary from place to place. Thus, in conformal space-time geometry, there is not a particular metric g_{ab}, but an equivalence class of metrics where the metrics ğ_{ab} and g_{ab} are considered to be equivalent if there is a smooth positive scalar field Ω for which ğ_{ab} = Ω g_{ab} (R. Penrose, 2012, The Basic Ideas of Conformal Cyclic Cosmology). |
conformal geometry hendese-ye hamdis Fr.: géométrie conforme The study of the set of angle-preserving transformations on a space. |
conformal mapping hamtâyeš-e hamdis Fr.: application conforme A continuous mapping u = f(x) of a domain D in an n-dimensional Euclidean space (n≥ 2) into the n-dimensional Euclidean space is called conformal at a point x_{0}∈ D if it has the properties of constancy of dilation and preservation of angles at this point. |
cosmic star formation peak cakâd-e keyhâni-ye diseš-e setâregân Fr.: pic de formation stellaire cosmique A crucial period in the history of the → Universe, when the bulk of stars in massive galaxies were likely formed. Observations of young stars in distant galaxies at different times in the past have indicated that the → star formation rate peaked at the → redshift of z ~ 2, some 10 billion years ago, before declining by a factor of around ten to its present value (P. Madau & Dickinson, 2014, arXiv:1403.0007). |
deform 1) vâdisidan; 2) vâdisândan Fr.: 1) se déformer; 2) déformer 1) To undergo → deformation. From O.Fr. déformer, from L. deformare "to disfigure," from → de- + → form. Vâdisidan, vâdisândan infinitive from vâdis, from vâ-, → de-, + dis, → form. |
deformable vâdisidani Fr.: déformable Capable of being → deformed. → deformable mirror |
deformable mirror âyene-ye vâdisidani Fr.: miroir déformable A very thin mirror whose shape can be changed by the force applied by many small pistons behind the mirror. Such a mirror is used in the → adaptive optics technique to correct the → wavefront affected by the → atmospheric turbulence. See also → tip-tilt mirror. → deformable; → mirror. |
deformation vâdis, vâdiseš, vâdisâneš Fr.: déformation Altering in the size or shape of a body. See also → deformable. Verbal noun of → deform. |
deformed vâdisidé Fr.: déformé Past participle of → deform. |
Descartes' formula disul-e Descartes Fr.: formule de Descartes A formula that gives the position of an image formed by highly → paraxial rays from a → spherical mirror. It is quite accurately given by: 1/x_{o} + 1/x_{i} = 2/x_{C}, where x_{o} is the distance along the → principal axis from the mirror to the object, x_{i} is the distance from mirror to image, and x_{C} is the distance from the mirror to its center of curvature. Any distance measured on the same side of the mirror as the reflecting surface is positive; on the other side, negative. Thus for a → concave mirror x_{C} is positive; for a → convex mirror, negative. |
dimensional formula disul-e vâmuni Fr.: formule dimensionnelle Symbolic representation of the definition of a physical quantity obtained from its units of measurement. For example, with M = mass, L = length, T = time, area = L^{2}, velocity = LT^{-1}, energy = ML^{2}T^{-2}. → dimensional analysis. → dimensional; → formula. |
elastic deformation vâdiseš-e kešâyand Fr.: déformation élastique A deformation of a → solid body in which the change (→ strain) in the relative position of points in the body disappears when the deforming stress is removed. See also → elastic limit. → elastic; → deformation. |
empirical formula disul-e ârvini Fr.: formule empirique 1) In physics, a mathematical equation that predicts observed results, but has
no known theoretical basis to explain why it works. |
Euler's formula disul-e Euler Fr.: formule d'Euler A formula which expresses an → exponential function
with an → imaginary number
→ exponent in terms of
→ trigonometric functions: |
form 1) dis, disé (#); 2) disidan (#); 3) disândan (#) Fr.: 1) forme; 2) se former; 3) former 1) (n.) General: The shape and structure of something as distinguished
from its material. From O.Fr. forme, from L. forma "form, mold, shape, case," origin unknown. 1)
Dis, disé "form, appearance," variants -diz, -diš (tandis
"body form, like a body; effigy;" mâhdis "moon-like;"
šabdiz "night color; a horse of
dark rusty color;" andiš- "to think, contemplate"), from Mid.Pers.
dêsag "form, appearance," dêsidan
"to form, build;" Av. daēs- "to show," daēsa- "sign, omen;"
cf. Skt. deś-
"to show, point out;" PIE *deik- "to show" (cf. Gk. deiknumi "to show,"
dike "manner, custom;" L. dicere "to utter, say;" O.H.G. zeigon,
Ger. zeigen "to show;" O.E. teon "to accuse," tæcan "to teach"). |
formal diseyi, disevar Fr.: formel 1) According to, or following established or prescribed forms, conventions, etc. M.E. formal, formel, from L. formalis, from → form + → -al. Diseyi, desevar, from dis, → form, + adj. suffixes -i and -var. |
formal language zabân-e disevar Fr.: langage formel A language designed for use in situations in which natural language is unsuitable, as for example in → mathematics, → logic, or → computer → programming. The symbols and formulas of such languages stand in precisely specified syntactic and semantic relations to one another (Dictionary.com). |
formal logic guyik-e diseyi, ~ disevar Fr.: logique formelle The traditional or → classical logic in which the → validity or → invalidity of a conclusion is deduced from two or more statements (→ premises). Based on Aristotle's (384-322 BC) theory of → syllogism, systematized in his book "Organon," its focus is not on what is stated (the content) but on the structure (form) of the → argument and the validity of the inference drawn from the premises of the argument; if the premises are true then the logical consequence must also be true. Formal logic is → bivalent, that is it recognizes only two → truth values: → true and → false. The basic principles of formal logic are: 1) → principle of identity, 2) → principle of excluded middle, and 3) → principle of non-contradiction. See also → symbolic logic, → fuzzy logic. |
formal system râžmân-e diseyi, ~ disevar Fr.: système formel In logic and mathematics, a system in which statements can be constructed and manipulated with logical rules. |
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