Negative Temperature - Heat and Molecular Energy Distribution

Heat and Molecular Energy Distribution

Negative temperatures can only exist in a system where there are a limited number of energy states (see below). As the temperature is increased on such a system, particles move into higher and higher energy states, and as the temperature increases, the number of particles in the lower energy states and in the higher energy states approaches equality. (This is a consequence of the definition of temperature in statistical mechanics for systems with limited states.) By injecting energy into these systems in the right fashion, it is possible to create a system in which there are more particles in the higher energy states than in the lower ones. The system can then be characterised as having a negative temperature. A substance with a negative temperature is not colder than absolute zero, but rather it is hotter than infinite temperature. As Kittel and Kroemer (p. 462) put it, "The temperature scale from cold to hot runs:

+0 K, . . ., +300 K, . . ., +∞ K, −∞ K, . . ., −300 K, . . ., −0 K."

Generally, temperature as it is felt is defined by the kinetic energy of atoms. Since there is no upper bound on momentum of an atom there is no upper bound to the number of energy states available if enough energy is added, and no way to get to a negative temperature. However, temperature is more generally defined by statistical mechanics than just kinetic energy (see below). The inverse temperature β = 1/kT (where k is Boltzmann's constant) scale runs continuously from low energy to high as +∞, . . ., −∞.

Read more about this topic:  Negative Temperature

Famous quotes containing the words heat, energy and/or distribution:

    Coal is a portable climate. It carries the heat of the tropics to Labrador and the polar circle; and it is the means of transporting itself whithersoever it is wanted. Watt and Stephenson whispered in the ear of mankind their secret, that a half-ounce of coal will draw two tons a mile, and coal carries coal, by rail and by boat, to make Canada as warm as Calcutta, and with its comfort brings its industrial power.
    Ralph Waldo Emerson (1803–1882)

    The welfare, the happiness, the energy and spirit of the men and women who do the daily work ... is the underlying necessity of all prosperity.... There can be nothing wholesome unless their life is wholesome; there can be no contentment unless they are contented.
    Woodrow Wilson (1856–1924)

    My topic for Army reunions ... this summer: How to prepare for war in time of peace. Not by fortifications, by navies, or by standing armies. But by policies which will add to the happiness and the comfort of all our people and which will tend to the distribution of intelligence [and] wealth equally among all. Our strength is a contented and intelligent community.
    Rutherford Birchard Hayes (1822–1893)