Fr.: affinité électronique
The amount of energy released or absorbed in the process in which an electron is added to a neutral atom or molecule in gaseous state to form a negative ion.
cagâli-ye elektroni (#)
Fr.: densité électronique
The degree of divergence of an ellipse from a circle.
From elliptic-, from elliptical + → -ity.
The ratio of energy radiated by a material to energy radiated by a black body at the same temperature.
Fr.: densité d'énergie
The amount of energy in the form of radiation per unit volume, expressed in ergs cm-3. In particular, the energy density of blackbody radiation at temperature T is aT4, where the radiation constant a = 7.56 × 10-15 erg cm-3 (K)-4.
1) A real thing.
From L.L. entitatem, from L.L. ens (genitive entis) "being, thing," from esse "to be," cognate with Pers. hast, ast, as below.
Hastâr, from hast (noun), as in hast-o-nist, or contraction of hasti "existence," from hastan "to be" (variant astan, ast "is;" Mid.Pers. (h)ast "is," (h)astih "existence;" O.Pers. ah- "to be," astiy "is;" Av. ah- "to be" (ahmī, ahī, astī); cf. Skt. as- "to be," ásti "is;" Gk. esti "is;" L. est "is;" Russ. yest "is;" Goth. ist; E. is), + suffix -âr (as in padidâr). Alternatively, from hast (noun), as above, + -âr contraction of -dâr (as in dustâr) present stem of dâštan "to have, to possess" (Mid.Pers. dâštan, O.Pers./Av. root dar- "to hold, keep back, maintain, keep in mind," Skt. dhr-, dharma- "law," Gk. thronos "elevated seat, throne," L. firmus "firm, stable," Lith. daryti "to make," PIE *dher- "to hold, support").
1) The state or quality of being equal.
M.E. from L. aequalitat-, stem of aequalitats, → equal + -ity.
Hamugi noun of hamug, → equal.
Fr.: signe d'égalité
Same as → equals sign.
Fr.: vitesse d'échapement
The speed an object must attain in order to free itself from the gravitational influence of an astronomical body. It is the minimum velocity for the object to enter a parabolic trajectory. The escape velocity is given by: Ve = (2GM/r)1/2, where G is the → gravitational constant, M is the mass of the astronomical body, and r is its radius. The escape velocity of the Earth is about 11.2 km s-1 that of the Moon is 2.4 km s-1. The escape velocity from the Sun is about 618 km s-1, and the solar escape velocity from Earth's orbit is about 42.1 km s-1.
Fr.: parité paire
A classical variable which does not change upon spatial inversion, such as time, energy, angular momentum and so on. → odd parity.
Even, from O.E. efen "level; equal," from P.Gmc. *ebnaz (cf. Ger. eben; Goth. ibns); → parity.
Hamâli, → parity; zowj "pair, couple; an even number," from Ar.
1) The state or quality of being explosive.
Fr.: photoconductivité extrinsèque
Photoconductivity due to the addition of impurities or external causes.
Fr.: gravité f(r)
An extension of Einstein's → general relativity
derived from relaxing the hypothesis that the
→ Hilbert-Einstein action for the
→ gravitational field is strictly linear. This was done by
replacing the → Ricci scalar,
R, with a non-linear function of R:
1) Ease in moving, acting, or doing.
Âsânâk, from âsân "easy," + relation suffix -âk, as in xorâk, pušâk, dârâk.
Philosophy of science: The concept according to which a proposition or theory cannot be scientific if it does not admit consideration of the possibility of its being false. According to Karl Popper (1902-1994), falsifiability is the crucial feature of scientific hypotheses. Any theory not falsifiable is said to be unscientific.
A property observed in certain materials characterized by the presence of a spontaneous electric polarization even in the absence of an external electric field. In the ferroelectric state the center of positive charge of the material does not coincide with the center of negative charge. This phenomenon is explained by spontaneous alignment of these permanent moments along the same direction. The term comes from the similarity with → ferromagnetism, but iron is not a ferroelectric. Ferroelectricity disappears above a critical temperature. Ferroelectric materials have been a fertile field for the study of → phase transitions.
Fr.: instabilité à traines
A type of instability that often occurs in fluids which are thermally stably stratified, but have an inhomogeneous composition. A well-known example, found in upper layers of the Earth's oceans, is → salt fingers. Similar fingering instabilities can occur in any other thermally stably stratified solution, provided the concentration of the slower-diffusing solute increases with height. The saturated state of this instability, → fingering convection, takes the form of tightly-packed, vertically-elongated plumes of sinking dense fluid and rising light fluid, and significantly enhances the vertical transport of both heat and chemical composition. The fingering instability occurs in stars within radiation zones that have an unstable mean → molecular weight → gradient (μ gradient). This situation is often found as a result of material accretion onto a star by anything from a single or multiple planets, to material from a dust-enriched or debris accretion disk, or material from a more evolved companion. It also naturally arises in the vicinity of the → hydrogen shell burning in → red giant branch (RGB) stars, and in thin element-rich layers near the surface of intermediate-mass stars. The fingering instability initially takes the form of thin tubes, hence the name "finger," within which the fluid moves vertically. The tubes rapidly break down, however, as a result of parasitic shear instabilities that develop inbetween them, and the fingering instability eventually saturates into a state of homogeneous fingering convection where the typical aspect ratio of the eddies is closer to one (P. Garaud et al., 2015, arXiv:1505.07759).
1) The quality of bending easily without breaking.
Fr.: aptitude à s'écouler, coulabilité
The ability of a body of matter (liquid, gas, loose particulate solid) to flow.
Tacandegi, from tacandé (originally tacandag), agent noun of tacidan, → flow, + noun suffix -i.