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mathematical conjecture hâšan-e mazdâhik Fr.: conjecture mathématique A statement that one expects to be true, but for which one does not yet know a proof. Once the → proof is found, the conjecture becomes a → theorem. → mathematical; → conjecture. |
mathematical expectation omid-e mazdâhik, bayuseš-e ~, ~ riyâzi Fr.: espérance mathématique In probability and statistics, of a random variable, the summation or integration, over all values of the random variable, of the product of the value and its probability of occurrence. Also called → expectation, → expected value. → mathematical; → expectation. |
Maxwell's demon pari-ye Maxwell Fr.: démon de Maxwell A → thought experiment meant to raise questions about the possibility of violating the → second law of thermodynamics. A wall separates two compartments filled with gas. A little "demon" sits by a tiny trap door in the wall. He is able to sort hot (faster) molecules from cold molecules without expending energy, thus bringing about a general decrease in → entropy and violating the second law of thermodynamics. The → paradox is explained by the fact that such a demon would still need to use energy to observe and sort the molecules. Thus the total entropy of the system still increases. Named after James Clerk Maxwell (→ maxwell), who first thought of this experiment; → demon. |
Maxwell's equations hamugešhâ-ye Maxwell Fr.: équations de Maxwell A set of four fundamental equations that describe the electric and
magnetic fields arising from varying electric charges and magnetic fields,
electric currents, charge distributions,
and how those fields change in time. In their vector differential form,
these equations are: → maxwell. It should be emphasized that the equations originally published by James Clerk Maxwell in 1873 (in A Treatise on Electricity and Magnetism) were 20 in number, had 20 variables, and were in scalar form. The German physicist Heinrich Rudolf Hertz (1857-1894) reduced them to 12 scalar equations (1884). It was the English mathematician/physicist Oliver Heaviside (1850-1925) who expressed Maxwell's equations in vector form using the notations of → gradient, → divergence, and → curl of a vector, thus simplifying them to the present 4 equations (1886). Before Einstein these equations were known as Maxwell-Heaviside-Hertz equations, Einstein (1940) popularized the name "Maxwell's Equations;" → equation. |
Maxwell-Boltzmann distribution vibâžš-e Maxwell-Boltzmann Fr.: distribution de Maxwell-Boltzmann The distribution law for kinetic energies (or, equivalently, speeds) of molecules of an ideal gas in equilibrium at a given temperature. → maxwell; → Boltzmann's constant; → distribution. |
mean daily motion jenbeš-e ruzâne-ye miyângin (#) Fr.: mouvement diurne moyen The average movement of a body along its orbit in one day, usually expressed in degrees. |
mean moon mâh-e miyângin (#) Fr.: lune moyenne A fictitious Moon that has the same average motion as the true Moon but that is not subject to any gravitational perturbations by other bodies. |
mean motion jonbeš-e miyângin (#) Fr.: mouvement moyen The average angular velocity of a satellite in an elliptical orbit. |
mean position neheš-e miyângin Fr.: position moyenne Same as → mean place. |
meditation segâleš (#) Fr.: méditation The act of meditating. → consideration. From L. meditatatus p.p. of meditari "to think over, reflect, consider," from PIE root *med- "to measure, limit, consider, advise," → mode. Verbal noun of → meditate. |
megatons of TNT megâton-e TNT (#) Fr.: megatonnes de TNT A unit of explosive force equal to one million metric tons of → T.N.T.. 1 megaton = 4.2 × 10^{22} → ergs = 4.2 × 10^{15} → joules. |
membership function karyâ-ye hamvandi Fr.: fonction d'adhésion One of several functions used in the → fuzzification and → defuzzification steps of a → fuzzy logic system to map the → nonfuzzy input values to → fuzzy linguistic terms and vice versa. A membership function is used to quantify a linguistic term. → membership; → function. |
mention 1) ayât; 2) ayâtidan Fr.: 1) mentionner; 2) mention 1) To refer briefly to; name, specify, or speak of (Dictionary.com). M.E. mencioun, from O.Fr. mencion "mention, memory, speech," from L. mentionem "a calling to mind, a speaking of," from root of Old L. minisci "to think," related to mens "mind," from PIE root *men- "to think;" cf. Pers. man, mân "thought, to think," → mind. Ayât, from Mid.Pers. ayât, ayâd "remembrance, recollection, memory;" Mod.Pers. yâd. |
meridian observation nepâheš-e nimruzâni Fr.: observation au méridien The observation of a star when it crosses an observer's meridian. → meridian; → observation. |
meridional nimruzâni Fr.: méridien Of, pertaining to, or resembling a meridian. From nimruzân, → meridian, + -i adj. suffix. |
meridional circulation parhuneš-e nimruzâni Fr.: circulation méridien The mass motion of material within a → rotating star generated by the star's departure from spherical symmetry. For a rotating star in which → centrifugal forces are not negligible, → radiative equilibrium and → hydrostatic equilibrium cannot be satisfied. In this condition energy transfer is accomplished by means of the physical motion of material. According to → von Zeipel theorem, the heating on an → equipotential surface is generally higher in the polar direction than in the equatorial direction, which drives a large scale circulation current rising at the pole and descending at the equator. As a consequence, → mixing of material takes place in the stellar interior; see also → Eddington-Sweet time scale. The meridional circulation plays an important role in the evolution of → massive stars. The circulation current was first suggested by Arthur S. Eddington in 1926 (The Internal Constitution of the Stars, Dover Pub. Inc., New York) and subsequently quantified by P. A. Sweet (1950, MNRAS 110, 548). → meridional; → circulation. |
meridional flow tacân-e nimruzâni Fr.: courant méridien Meteo.: A flow between the poles, or between the equator and the poles. A positive value indicates flow away from the equator; a negative value, flow toward the equator. → meridional; → flow. |
meridional magnetic field meydân-e meqnâtisi-ye nimruzâni Fr.: champ magnétiquue méridien In the → solar dynamo model, a magnetic field that points from the north to south or south to north. → meridional; → magnetic; → field. |
meson meson Fr.: méson A nuclear particle with a mass intermediate between that of a proton and an electron, which is believed to be responsible for the strong nuclear force. In contrast to the case of baryons or leptons, meson number is not conserved: like photons, mesons can be created or destroyed in arbitrary numbers. Their charge can be positive, negative, or zero. From mes-, meso-, from Gk. mesos "middle," akin to L. medius, Pers. miyân, → medium, → middle, + -on a suffix used in the names of subatomic particles. |
metal-rich environment pargir-e porfelez Fr.: environnement riche en métaux An environment (→ galaxy, → nebula) whose → metallicity is larger than that of the → Milky Way galaxy. → metal; → rich; → environment. |
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