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: 701
relativistic speed
  تندی ِ بازانیگی‌مند   
tondi-ye bâzânigimand

Fr.: vitesse relativiste   

Same as → relativistic velocity.

relativistic; → speed.

relativistic spin precession
  پیشایان ِ آسه‌ی ِ چرخش ِ بازانیگی‌مند   
pišâyân-e âse-ye carxeš-e bâzânigi-mand

Fr.: précession de l'axe de rotation relativiste   

The change in the direction of the → rotation axis of a → pulsar in a → binary pulsar. In such a system, → geodetic precession leads to a relativistic → spin-orbit coupling, analogous of → spin-orbit coupling in atomic physics. In consequence, the pulsar spin precesses about the total → angular momentum, changing the relative → orientation of the pulsar toward Earth (Damour & Ruffini, 1974). As a result, the angle between the pulsar → rotation axis and our → line of sight changes with time, so that different portions of the emission beam can be observed leading to changes in the measured pulse profile. In extreme cases, the precession may even move the beam out of our line of sight and the pulsar may disappear as predicted for PSR 1913+16 for the year 2025.

relativistic; → spin; → precession.

relativistic velocity
  تندای ِ بازانیگی‌مند   
tondâ-ye bâzânigimand

Fr.: vitesse relativiste   

The velocity of a body when it is a significant fraction of the → speed of light.

relativistic; → velocity.

relativity
  بازانیگی   
bâzânigi

Fr.: relativité   

General: The state or fact of being relative.
Physics: 1) Short for the → Galilean relativity.
2) Short for the → relativity theory of Einstein.

Relativity, from → relative + → -ity.

relativity of simultaneity
  بازانیگی ِ همزمانی   
bâzânigi-ye hamzamâni

Fr.: relatitivité de simultanéité   

A basic concept of → special relativity whereby → events that are simultaneous in one → reference frame are not simultaneous in another reference frame moving with respect to the first.

relativity; → simultaneity.

relativity principle
  پروز ِ بازانیگی   
parvaz-e bâzânigi

Fr.: principe de relativité   

The requirement employed by Einstein in his relativity theories, that the equations describing the laws of physics are the same in all frames of reference. This statement and that of the constancy of the speed of light constitute the founding principles of special relativity.

Relativity; → principle.

relativity theory
  نگره‌ی ِ بازانیگی   
negare-ye bâzânigi

Fr.: théorie de la relativité   

The → theory of relativity.

theory; → relativity.

relativize
  بازانی کردن   
bâzâni kardan

Fr.: relativiser   

To regard as or make one thing relative to something else.

relative + → -ize.

relax
  واهلیدن   
vâhelidan (#)

Fr.: relaxer, se relaxer   

To lessen the force, strength or intensity of something.

m M.E., from O.Fr. relaxer from L. relaxare "relax, loosen, open," from → re- "back" + laxare "loosen," from laxus "loose."

Vâhelidan, from vâ-, → re-, + helidan, heštan "to place, put" from Mid.Pers. hištan, hilidan "to let, set, leave, abandon;" Parthian Mid.Pers. hyrz; O.Pers. hard- "to send forth," ava.hard- "to abandon;" Av. harəz- "to discharge, send out; to filter," hərəzaiti "releases, shoots;" cf. Skt. srj- "to let go or fly, throw, cast, emit, put forth;" Pali sajati "to let loose, send forth."

relaxation
  واهلش   
vâheleš (#)

Fr.: relaxation   

1) The evolution of the properties of a physical system which has been disturbed and which regains its equilibrium condition once the disturbing action has ceased. Relaxation is the response of the system to the perturbation. The time required by the system to regain its condition of minimum energy is called the → relaxation time.
2) Math.: In numerical analysis, a method of solving equations in which the errors, or residuals, resulting from an initial approximation are reduced by succeeding approximations until finally all are within the toleration limit.

Verbal noun of → relax.

relaxation time
  زمان ِ واهلش   
zamân-e vâhaleš

Fr.: temps de relaxation   

The characteristic length of time that is required for a system undergoing → relaxation to move to its equilibrium state. If the system follows an exponential law G = G0 exp(-t / τ), the relaxation time is the time required for G to obtain the fraction 1/e of its initial value G0.

relaxation; → time.

relaxed system
  راژمان ِ واهلیده   
râžmân-e vâhalidé

Fr.: système relaxé   

A → dynamical system that has regained its → equilibrium. Especially a system in which the kinetic and potential energies obey a specific relationship known as the → virial theorem.

P.p. from relax, → relaxation.

relay
  اسک   
ask (#)

Fr.: relais   

General: The act of passing something along from one person, group, or device to another.
Electronics: An electronic or electromechanical switching device, typically operated by a low voltage, that controls a higher-voltage or higher-power circuit and turns it on or off.
A device consisting of a receiver and a transmitter, used to receive and retransmit signals.

M.E. relaien "to unleash fresh hounds in a hunt," from M.Fr. relai "reserve pack of hounds or other animals," from O.Fr. relaier "to exchange tired animals for fresh," literally "to leave behind," from → re- "back" + laier "to leave."

Ask "relay horse kept in stations for the use of messengers," maybe from asbhorse.

reliability
  استیگانی   
ostigâni

Fr.: fiabilité   

1) The state or quality of being reliable.
2) A statement of the error or precision.

reliable; → -ity.

reliable
  اُستیگان   
ostigân (#)

Fr.: fiable   

Able to be trusted to be accurate or to provide a correct result.

From rely, from O.Fr. relier "fasten, rally, oblige," from L. religare "fasten, bind fast," from → re-, intensive prefix, + ligare "to bind" + → -able.

Ostigân, from Mid.Pers. ostigân "reliable, firm, sure," from ost "firm, reliable."

reliable data
  داده‌های ِ استیگان   
dâdehâ-ye ostigân

Fr.: données fiables   

Date which are not affected by sampling error or bias.

reliable; → data.

reluctance
  ستهی   
setehi (#)

Fr.: réluctance   

The ratio of the magnetomotive force acting in a magnetic circuit to the magnetic flux. Also called magnetic resistance, it is analogous to resistance in an electrical circuit.

Reluctance "act of struggling against;" L. reluctari "to struggle against," from → re- "against" + luctari "to struggle."

Setehi "contention, litigation," related to setihidan "to quarrel, brawl," setiz, "battle, combat, conflict," setizidan "to fight;" Mid.Pers. stêzag "quarrel, strife;" Av. stij- "battle;" cf. Skt. steg- "to assail;" Gk. stizein "to prick, puncture," stigma "mark, puncture;" O.E. stician "to pierce, stab;" E. stick (v.); PIE *steig- "to sting, stab."

rem
  رم   
rem (#)

Fr.: rem   

A unit used for measuring the effective dose of radiation received by a living organism. It is the quantity of radiation whose biological effect is equal to that produced by one → roentgen of → X-rays. 1 rem = 0.01 sievert (Sv) or 10 → millisieverts.

Rem, acronym for roentgen equivalent: man. The unit was introduced in 1944 by Herbert M. Parker (1910-1984), a radiation physicist and co-inventor of the Paterson-Parker Radium Therapy System.

remanence
  پسماند   
pasmând (#)

Fr.: rémanence   

An effect that remains in a system for a while after the physical cause has been removed. For example the light remaining in a detector after elimination of the source, or the magnetic induction that remains in a material after removal of the magnetizing field.

From reman(ent), → remanent + -ence a noun suffix.

Noun of → pasmân.

remanent
  پسمان   
pasmân

Fr.: rémanent   

Possessing → remanence.

M.E. from L. remanent- (stem of remanens), pr.p. of remanere "to remain, stay behind," from → re- "back" + manere "to stay, remain," cognate with Pers. mândan "to stay, remain," as below.

Pasmân, from pas- "behind," variant pošt "back; the back; behind" (Mid.Pers. pas "behind, before, after;" O.Pers. pasā "after;" Av. pasca "behind (of space); then, afterward (of time);" cf. Skt. paścā "behind, after, later;" L. post, as above; O.C.S. po "behind, after;" Lith. pas "at, by;" PIE *pos-, *posko-) + mân present stem of mândan "to remain, stay" (mân "house, home;" Mid.Pers. mândan "to remain, stay;" O.Pers. mān- "to remain, dwell;" Av. man- "to remain, dwell; to wait;" Gk. menein "to remain;" L. manere "to stay, abide" (Fr. maison, ménage; E. manor, mansion, permanent); PIE base *men- "to remain, wait for").

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