An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

A → relative tensor of order zero.

→ relative; → invariant.

→ magnetic permeability.

→ relative; → permeability.

The ratio of the sine of the angle of incidence to the sine of the angle of refraction for a ray passing out of one of the media into the other.

→ relative; → refractive; → index.

Same as → Wolf number and → sunspot number.

→ relative; → sunspot; → number.

A generalized tensor concept that is characterized by a → Jacobian matrix of transformation raised to a power called → weight of a tensor density. In practice, only relative tensors of weight 1 or -1 are used. The product of a relative tensor of weight -1 by another tensor of weight 1 is an → absolute tensor. Same as → tensor density.

→ relative; → tensor.

A → relative tensor of → order  → one.

→ relative; → vector.

For two objects A and B, the velocity which B, supposing itself at rest, assigns to A.

→ relative; → velocity.

In a relative manner; in relation to something else.

From → relative + -ly "-vâr, -âné."

The belief that truth is relative and may vary from individual to individual, from group to group, or from time to time, having no objective standard.

From → relative + -ism a suffix used in the formation of nouns denoting action or practice, state or condition, principles, doctrines, etc.

Bâzâni-bâvari, from bâzâni, → relative, + bâvari, from bâvar "belief" (Mid.Pers. wâbar "beleif;" Proto-Iranian *uar- "to choose; to convince; to believe;" cf. Av. var- "to choose; to convince" varəna-, varana- "conviction, faith;" O.Pers. v(a)r- "to choose; to convince;" Skt. vr- "to choose," vara- "choosing").

An adherent or advocate of relativism.

From → relative + -ist a suffix of nouns.

Adj. from → relativism.

1) Physics: Relating to the → relativity theory.
2) Philosophy: Involving or characterized by → relativism.
See also:
→ non-relativistic, → relativistic aberration, → relativistic Doppler effect, → relativistic effect, → relativistic mass, → relativistic particle, → relativistic precession, → relativistic quantum mechanics, → relativistic redshift, → relativistic speed, → relativistic spin precession, → relativistic velocity, → ultrarelativistic, → ultrarelativistic gas.

From → relativist + → -ic.

The aberration of light for an object moving with → relativistic speed. In contrast to the classical case, the → Lorentz transformation between the → rest frame of the observer and that of the object must be used. Relativistic aberration is expressed by the equation: cos φ' = (cos φ - )/(1 - cos φ.v/c), where φ is the classical → aberration angle, v the speed of the Earth, and c the → speed of light. It can also be expressed as: tan φ' = -(c/v)(1 - v²/c)^1/2.

→ relativistic; → aberration.

The Doppler effect when the relative motion of the source and the observer is comparable to the speed of light. In that case the classical Doppler formula should be corrected for effects of the special theory of relativity (Lorentz transformation).

→ relativistic; → Doppler effect.

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

→ relativistic; → effect.

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 m_t = 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.

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

→ relativistic; → particle.

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.

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

→ relativistic; → quantum mechanics.

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

→ relativistic; → redshift.

Same as → relativistic velocity.

→ relativistic; → speed.