Logic: The quality of an argument when its conclusion is false even if all the premises are true.
Lack of → validity.
Fr.: plan invariable
Mechanics: For a rotating rigid body not subject to external torque, a plane which is perpendicular to the angular momentum vector of the body, and which is always tangent to its → inertia ellipsoid.
Any property of a physical law or quantity that is unchanged after the application of certain classes of transformations.
Invariance; noun of → invariant.
A quantity which is independent of the coordinate system. For example the vector product of two vectors is an invariant since it depends only on the magnitude of the two vectors and the angle between them.
From negation prefix → in- + variant, from L. variantem (nom. varians), pr.p. of variare "to change," from varius "varied, different, spotted."
Nâvartâ, from negation prefix nâ-, → in-, + vartâ adj., from vartidan, variant of gardidan, gaštan "to change; to turn," Mid.Pers. vartitan; Av. varət- "to turn, revolve;" cf. Skt. vrt- "to turn, roll," vartate "it turns round, rolls;" L. vertere "to turn;" O.H.G. werden "to become;" PIE base *wer- "to turn, bend."
To create or design a new type of thing (process, machines, etc.). See also → discover.
From L. inventus, p.p. of invenire "to encounter, come upon, find," from in- "upon" + ven-, from venire "to come" + -tus p.p. suffix.
Parâvidan on the model of dialectals Munji purôv-/purvi-, Yidgha pura-/prvei- "to find, obtain," Shughni, Roshani, Bartangi, Yazghulami firâp-fiript "to arrive at, reach;" prefixed (*fra-/*pra-) from Proto-Iranian *Hap/f- "to reach, attain;" cf. Av. ap- "to reach, attain;" related to Pers. yâb-, yâftan "to find" (Cheung 2007).
The action or of inventing or something invented.
Verbal noun of → invent.
A person who invents.
Opposite to or reversing something.
From L. inversus, p.p. of invertere, → invert.
Vârun "inverse, upside down," from vâ- "back, backward, again, re-," variant of bâz-, from Mid.Pers. abâz-, apâc-, O.Pers. apa- [pref.] "away, from;" Av. apa- [pref.] "away, from," apaš [adv.] "toward the back;" cf. Skt. ápāñc "situated behind."
Fr.: axiome d'inverse
A basic rule in → group theory stating that for any element a of a group there is an element a-1 such that a * a-1 = a-1 * a = e.
inverse beta decay
tabâhi-ye vârun-e β (#)
Fr.: désintégration β inverse
A collision of a proton with an electron that produces a neutron and an electron neutrino. See → beta decay.
Fr.: Bremsstrahlung inverse
The absorption of a photon by an electron in a strong electric field. → bremsstrahlung.
inverse Compton effect
oskar-e Compton-e vârun
Fr.: effet Compton inverse
A → scattering process by which fast-moving, energetic particles transfer energy to photons, decreasing the wavelength of the radiation. This is a particularly important effect in astrophysics and cosmology since it explains the → Sunyaev-Zel'dovich effect.
inverse P Cygni line profile
farâpâl-e P Cygni-ye vârun
Fr.: profil P Cygni inverse
A line profile in which the emission is on the blue side of the absorption. It is usually interpreted as the redshift of the absorption component relative to emission lines, which necessitates infall of matter.
inverse square law
qânun-e tavân-e do-ye vârun, qânun-e câruš-e vârun
Fr.: loi en carré inverse
inverse Zeeman effect
oskar-e Zeeman-e vârun
Fr.: effet Zeeman inverse
The → Zeeman effect obtained in absorption. The phenomenon is observed by sending white light through an absorbing vapor when the latter is subjected to a uniform magnetic field. The laws governing the inverse effect are similar to those for the direct effect.
Meteo.: A departure from the usual decrease or increase with altitude of the value of an atmospheric property. It almost always refers to a temperature inversion, i.e., an increase in temperature with altitude. Chemistry: To subject to → inversion.
Verbal noun of → invert.
Fr.: couche d'inversion
Meteo.: The atmospheric layer in which the temperature gradient is
inverted, that is increases; → inversion. The inversion layer
tends to prevent the air below it from rising, thus trapping any pollutants that are present.
Fr.: inververtir, renverser
To turn upside down.
From M.Fr. invertir, from L. invertere "turn upside down, turn about," from → in- "in, on" + vertere "to turn;" cf. Pers. gardidan, gaštan "to turn, to change;" Mid.Pers. vartitan; Av. varət- "to turn, revolve;" Skt. vartati; O.H.G. werden "to become;" PIE base *wer- "to turn, bend."
Vâgardândan, from vâ-, → re-, +
gardândan, from gardidan "to turn; to change,"
from Mid.Pers. vartitan;
Av. varət- "to turn, revolve;" cf.
Skt. vrt- "to turn, roll," vartate "it turns round, rolls;"
L. vertere "to turn;" O.H.G. werden "to become;"
PIE base *wer- "to turn, bend."