An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 712
relativistic effect
  اسکر ِ بازانیگی‌مند   
oskar-e bâzânigimand

Fr.: effet relativiste   

A physical phenomenon described only by the theories of → special relativity or → general relativity.

relativistic; → effect.

relativistic mass
  جرم ِ بازانیگی‌مند   
jerm-e bâzânigimand

Fr.: masse relativiste   

In → special relativity, the mass that is assigned to a body in motion. Einstein demonstrated that the velocity of the observer has an effect on the way inertial mass is measured. The relativistic mass is expressed by mt = m0 / [1 - (v/c)2]1/2, where m0 is the → rest mass, v is the velocity, and c the → velocity of light. The experimental evidence for this phenomenon is observed in the mass of high-speed electrons accelerated by magnetic fields. This formula shows that it is impossible for a mass to be accelerated to the velocity of light in a vacuum.

relativistic; → mass.

relativistic particle
  ذرّه‌ی ِ بازانیگی‌مند   
zarre-ye bâzânigimand

Fr.: particule relativiste   

A particle which has a speed comparable to the velocity of light.

relativistic; → particle.

relativistic precession
  پیشایان ِ بازانیگی‌مند   
pišâyân-e bâzânigimand

Fr.: précession relativiste   

A → general relativistic phenomenon in which the line joining the → apsides of an orbit gradually rotates in a → prograde direction. Also called the → orbital precession and → perihelion precession. Although the general relativistic precession of Mercury's orbit is extremely small, the similar precession observed in the orbit of the → binary pulsar PSR B1913+16 amounts to 4.23 degrees per year, i.e. 36,000 times greater than the → advance of perihelion of Mercury.

relativistic; → precession.

relativistic quantum mechanics
  کو‌آنتوم مکانیک ِ بازانیگی‌مند   
kuântom mekânik-e bâzânigimand

Fr.: mécanique quantique relativiste   

A quantum theory that incorporates special relativity, for example, → quantum electrodynamics.

relativistic; → quantum mechanics.

relativistic redshift
  سرخ‌کیب ِ بازانیگی‌مند   
sorx kib-e bâzânigimand

Fr.: décalage vers le rouge relativiste   

A redshift caused by the → relativistic Doppler effect. → gravitational redshift.

relativistic; → redshift.

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.


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.

  بازانی کردن   
bâzâni kardan

Fr.: relativiser   

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

relative + → -ize.

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."

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.

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.


Fr.: fiabilité   

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

reliable; → -ity.

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