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:
“Glories, like glow-worms, afar off shine bright,
But looked to near, have neither heat nor light.”
—John Webster (1580–1625)
“But often the presence of mind and energy of a person remote from the spotlight decide the course of history for centuries to come.”
—Stefan Zweig (18811942)
“The question for the country now is how to secure a more equal distribution of property among the people. There can be no republican institutions with vast masses of property permanently in a few hands, and large masses of voters without property.... Let no man get by inheritance, or by will, more than will produce at four per cent interest an income ... of fifteen thousand dollars] per year, or an estate of five hundred thousand dollars.”
—Rutherford Birchard Hayes (1822–1893)