de Broglie hypothesis
engâre-ye de Broglie
Fr.: hypothèse de de Broglie
The suggestion by Louis de Broglie in 1924 whereby if → electromagnetic waves possess particle properties (→ particle nature), then it might be reasonable to suppose that material particles, such as → electrons, should possess wave properties (→ wave nature). The de Broglie hypothesis was based on the intuitive feeling that nature seems to have strong attachment to symmetry. In other words, if radiation has particle-like properties, then material particles should possess wave-like properties. At the time no direct experimental evidence was present for the validity of this suggestion. The first confirmation of de Broglie's hypothesis was provided by the → Davisson-Germer experiment. See also → wave-particle duality;
de Broglie wavelength
mowjtul-e de Broglie
Fr.: longueur d'onde de Broglie
de Sitter Universe
giti-ye de Sitter
Fr.: Univers de de Sitter
A solution to → Einstein's field equations of → general relativity which contains no ordinary matter (ΩM = 0) or radiation (ΩR = 0), is → Euclidean (k = 0), but has a → cosmological constant (ΩΛ > 0). The Universe expands exponentially forever. This solution was the first model expanding of → expanding Universe. See also → empty Universe, → Milne Universe.
After the Dutch mathematician and physicist Willem de Sitter (1872-1934) who worked out the model in 1917; → universe.
de Vaucouleurs law
qânun-e de Vaucouleurs
Fr.: loi de Vaucouleurs
de Vaucouleurs radius
šo'â'-e de Vaucouleurs
Fr.: rayon de Vaucouleurs
After the French-born American astronomer Gérard de Vaucouleurs (1918-1995); → radius.
vâ- (#), foru- (#)
A prefix occurring in loanwords from L. to indicate: 1) Opposition, reversal: decentralize, decode, deactivate, de-emphasis 2) Removal from: dethrone. 3) Reduction, degradation: declass, devalue. 4) reversal: detract, detect. 5) Derivation from: derive, deverbative.
M.E., from O.Fr. de-, des-, partly from L. de- "from, down, away," and partly from L. → dis-.
Prefix vâ- denoting "reversal, opposition; separation; repetition; open;
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
Transition from an excited energy state to a lower energy level, as in spectral line formation or particle emission from an atomic nucleus.
To cause a spacecraft to leave its operational orbit to enter a descent phase or to change course.
Of a spacecraft, the act or process of departing from an operational orbit. → de-orbit.
Noun form of → de-orbit.
A method for estimating the real orientation of a field and/or related velocities/separations from two-dimensional images.
Fr.: magnitude dérougie
A magnitude which has been corrected for the interstellar reddening.
The process that de-reddens. The state of being de-reddened.
Verbal noun of → de-redden.
1) Deprived of life.
M.E. deed, O.E. dead "dead;" cf. O.S. dod, Dan. død, Swed. död, Du. dood, O.H.G. tot, Ger. tot; PIE *dhou-toz-, from base *dheu- "to die."
Mordé "dead," p.p. of mordan, mir- "to die," → death.
Fr.: pixel mort
Of a → CCD detector, a pixel that is not sufficiently active.
The act of dying; the end of life.
M.E. deeth, O.E. deað (cf. O.S. doth, O.Fris. dath, Du. dood, O.H.G. tod, Ger. Tod, O.N. dauði, Dan. død, Swed. död, Goth. dauþas "death"), from *dheu- "to die" + *-thuz "-th;"
Marg "death," from Mid.Pers. marg "death;" Av. mahrka- "death," mərəxš- "ruin;" related to Mod.Pers. mordan (present stem mir-) "to die;" Mid.Pers. murdan "to die;" O.Pers. mrt- "to die," amriyta "dies," martiya- "(mortal) man" (Mod.Pers. mard "man"); Av. mərəta- "died;" cf. Skt. mar- "to die," mrti- "death," marc- "to damage, hurt, injure;" PIE base *mor-/*mr- "to die." Cognates in other IE languages: Gk. emorten "died," ambrotos "immortal;" L. morior "I die," mortuus "dead" (Fr. mourir "to die," mort "dead"); Arm. merani- "to die;" O.C.S. mrutvu "dead;" O.Ir. marb; Welsh marw "died;" O.E. morþ "murder;" Lith. mirtis.
1) vâzat; 2) vâzatidan
Fr.: 1) débat; 2) débattre
1a) A → discussion, as of a public question in an
assembly, involving opposing viewpoints.
Fr.: soustraire le biais
To substract the → bias from a flat-field or science frame obtained using an electronic detector.
Fr.: soustraction du biais
Verbal noun of → debias.