population en température négative

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• Temperature — This article is about the thermodynamic property. For other uses, see Temperature (disambiguation). A map of global long term monthly average surface air temperatures i …   Wikipedia

• Negative temperature — In physics, certain systems can achieve negative temperatures; that is, their thermodynamic temperature can be a negative quantity. Negative temperatures can be expressed as negative numbers on the kelvin scale. Temperatures that are expressed as …   Wikipedia

• Population inversion — In physics, specifically statistical mechanics, a population inversion occurs when a system (such as a group of atoms or molecules) exists in state with more members in an excited state than in lower energy states. The concept is of fundamental… …   Wikipedia

• Thermodynamic temperature — is the absolute measure of temperature and is one of the principal parameters of thermodynamics. Thermodynamic temperature is an “absolute” scale because it is the measure of the fundamental property underlying temperature: its null or zero point …   Wikipedia

• Excitation temperature — The Excitation Temperature (T {ex}) (often called the spin temperature for the 21 cm line) is defined for a population of particles via the Boltzmann factor. It satisfies :frac{n u}{n l} = frac{g u}{g l} exp{( frac{Delta E}{k T {ex)},where nu and …   Wikipedia

• Germany — /jerr meuh nee/, n. a republic in central Europe: after World War II divided into four zones, British, French, U.S., and Soviet, and in 1949 into East Germany and West Germany; East and West Germany were reunited in 1990. 84,068,216; 137,852 sq.… …   Universalium

• Croatia — …   Wikipedia

• RUSSIE (géographie) — En 1985, Mikhaïl Gorbatchev engageait l’U.R.S.S. dans la perestroïka, nouvelle politique qui se transforma bien vite en séisme géopolitique pour le continent européen. En 1989, les démocraties populaires s’effondraient. En 1990 et 1991, l’U.R.S.S …   Encyclopédie Universelle

• Perth (Australie-Occidentale) — 31°57′00″S 115°52′00″E / 31.95, 115.866667 …   Wikipédia en Français

• Vin blanc — Un verre de vin blanc. Le vin blanc est un vin produit par la fermentation alcoolique de raisins à pulpe non colorée et à pellicule blanche ou noire. Il est traité de façon à conserver une couleur jaune transparente au produit final. La grande… …   Wikipédia en Français

• Ukraine — /yooh krayn , kruyn , yooh krayn/, n. a republic in SE Europe: rich agricultural and industrial region. 50,684,635; 223,090 sq. mi. (603,700 sq. km). Cap.: Kiev. Russian, Ukraina. Formerly, Ukrainian Soviet Socialist Republic. * * * Ukraine… …   Universalium