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

1) To express as a number or amount.
2) In predicate logic: To express by a → symbol how many of the → individuals have the property in common.

M.L. quantificare, from to L. quant(us) "how much?" + -ificare "-ify."

Candâyidan infinitive of candâ, → quantity + -idan.

The apparent slow motion of the → radiant of a → meteor shower from night to night against the background stars due to the Earth moving in its orbit around the Sun.

→ radiant; → drift.

A process of → radiative transfer in which photons are repeatedly absorbed and re-emitted by matter particles.

→ radiative; → diffusion.

1) Math.: The process of determining the length of a curve.
2) Physics: Conversion of an alternating into a direct current.
3) Astro.: The process of rectifying a spectrum.

Verbal noun of → rectify.

A spectrum after correction for detector's → baseline.

Rectified p.p. of → rectify; → spectrum.

1) General: A person or thing that rectifies.
2) Physics: A device for transforming an → alternating current into a → direct current.

Agent noun of → rectify.

1) General: To make, put, or set right; to correct.
2) Electricity: To convert an → alternating current into a → direct current.
3) Chem.: To refine a substance, especially by repeated distillation or sublimation.

M.E. rectifien, from O.Fr. rectifier "to make straight," from L.L. rectificare "make right," from L. rectus "straight," cognate with Pers. râst, as below, → right + root of facere "to make, do, perform" (cf. Fr. faire, Sp. hacer), from PIE base *dhe- "to put, to do" (cf. Mod.Pers. dâdan "to give;" O.Pers./Av. dā- "to give, grant, yield," dadāiti "he gives; puts;" Skt. dadáti "puts, places;" Hitt. dai- "to place;" Gk. tithenai "to put, set, place;" Lith. deti "to put;" Czech diti, Pol. dziac', Rus. det' "to hide," delat' "to do;" O.H.G. tuon, Ger. tun, O.E. don "to do").

Râstidan, literally "to make straight, right," infinitive from râst cognate with L. rectus "straight," → right.

A shift in the lines of an object's spectrum toward longer wavelengths. Redshift indicates that an object is moving away from the observer. The larger the redshift, the faster the object is moving. Redshift is expressed by z = Δλ/λ = v/c, where λ is the wavelength, Δλ the wavelength shift, v the velocity of the source relative to the observer, and c the → speed of light. When v approaches c, redshift is expressed by the → relativistic formula z = ((1 +v/c)/(1 - v/c))^½ - 1.

→ red; → shift.

The space corresponding to → redshift measurements, as contrasted with real space. See also → redshift space distortion

→ redshift; → space.

The distortion observed in → redshift space of → galaxy clusters caused by peculiar velocities of the members (→ peculiar velocity). In a perfectly homogeneous → Friedmann-Lemaitre Universe the redshifts would accurately measure radial distances from the observer, and the mapping from real space to redshift space would simply be an identity. In an inhomogeneous Universe the peculiar velocities associated with any inhomogeneous structure will introduce a distortion in this mapping (N. Kaiser, 1987, MNRAS 227, 1). See also: → fingers of God, → Kaiser effect.

→ redshift; → space; → distortion;.

A survey of a large region of the sky to measure the redshifts of all the galaxies down to a certain limiting magnitude.

→ redshift; → survey.

The correlation, first established by E. Hubble, between the cosmological recession velocities of galaxies and their distances.

→ redshift; → distance; → relation.

A spectral line whose wavelength does not coincide with its theoretical value and is shifted toward longer wavelengths.

→ red; → shift; → line.

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

→ relativistic; → redshift.

A → manifold on which there is a defined → Riemannian metric (Douglas N. Clark, 2000, Dictionary of Analysis, Calculus, and Differential Equations).

→ Riemannian; → metric.

1) General: a gap or break made by splitting, cleaving, etc.; fissure; cleft.
2) Geology: A narrow cleft, fissure, or other opening in rock, made by cracking or splitting.
3) Geology: An elongated trough in the Earth's crust bounded by → faults.

M.E., from a Scandinavian source; cf. Dan., Norw. rift "a cleft."

1) Câk "fissure, rupture, cleft, crack," related to caqidan "to drive a nail, strike together, fix a spike;" caxidan "to quarrel, strive;" diatectal Shughni cuγ, Roshani coγ "breaking, tearing, ripping up;" Malâyeri ceqidan "cracking of a cold porcelain bowl when receiving hot water;" Yazghulami cok-, coxt "to pound, to stamp;" Wakhi cuk-, cukt "to strike;" Ossetic cædyn "to shake, strike iron;" Lori cok "a mark fixed to separate two grounds;" Sogd. cax "to battel, fight;" Mid.Pers. (prefixed) pacên "copy" (see also Cheung 2007). Gosal-darré, from gosal, → fault, + darré, → valley.

A long, narrow valley formed by the lowering of land between two → faults. Also called → graben.

→ rift; → valley.

Of or pertaining to science or the sciences.
Systematic or accurate in the manner of an exact science.

From M.Fr. scientifique, from M.L. scientificus "pertaining to science," from L. scientia "knowledge," → science, + -ficus "making," from facere "to make." → -ic

Dâneši, dânešik, from dâneš, → science + -i, -ik, → ic.

An agreement by competent observers of a series of observations of the same phenomena. From time to time scientific facts are revised by additional data (G. Smooth, Lawrence Berkeley Lab website).

→ scientific; → fact.

The process by which scientists, collectively and over time, endeavor to construct an accurate (that is, reliable, consistent, and non-arbitrary) representation of the world. The scientific method has four steps:
1) Observation and description of a phenomenon or group of phenomena.
2) Formulation of an hypothesis to explain the phenomena. In physics, the hypothesis often takes the form of a causal mechanism or a mathematical relation.
3) Use of the hypothesis to predict the existence of other phenomena, or to predict quantitatively the results of new observations.
4) Performance of experimental tests of the predictions by several independent experimenters and properly performed experiments.
If the experiments bear out the hypothesis it may come to be regarded as a theory or law of nature. If the experiments do not bear out the hypothesis, it must be rejected or modified. What is key in the description of the scientific method just given is the predictive power (the ability to get more out of the theory than you put in) of the hypothesis or theory, as tested by experiment. It is often said in science that theories can never be proved, only disproved. There is always the possibility that a new observation or a new experiment will conflict with a long-standing theory (Frank L. H. Wolfs, University of Rochester).

→ scientific; → method.