Boltzmann constant
Symbol k. The ratio of the universal gas constant (R) to the Avogadro constant (N A). It may be thought of therefore as the gas constant per molecule:k = R/N A = 1.380 658(12) × 10−23 J K−1 It is ...
Boltzmann equation
An equation used in the study of a collection of particles in nonequilibrium statistical mechanics, particularly their transport properties. The Boltzmann equation describes a quantity called the ...
Boltzmann formula
An equation concerning the entropy S of a system that derives from statistical mechanics. It states that entropy is related to the number W of distinguishable ways in which the equation S = k lnW, ...
conservation law
A law stating that the total magnitude of a certain physical property of a system, such as its mass, energy, or charge, remain unchanged even though there may be exchanges of that property between ...
energeticism
The physical view that energy is the fundamental element in all physical change. It was propounded by the chemist Wilhelm Ostwald (1853–1932), but rebutted by Ludwig Boltzmann and Max Plank.
entropy
1 Measure of disorder or unavailable energy in a thermodynamic system; the measure of increasing disorganization of the universe.2 See least-work principle; and least-work profile.
equipartition of energy
The theory, proposed by Ludwig Boltzmann and given some theoretical support by James Clerk Maxwell, that the energy of gas molecules in a large sample under thermal equilibrium is equally divided ...
Erwin Schrödinger
(1887–1961)Austrian physicist, who became professor of physics at Berlin University in 1927. He left for Oxford to escape the Nazis in 1933, returned to Graz in Austria in 1936, and then left again ...
fundamental constants
Those parameters that do not change throughout the universe. The charge on an electron, the speed of light in free space, the Planck constant, the gravitational constant, the electric constant, and ...
ideal gas
A hypothetical gas that obeys the gas laws exactly. An ideal gas would consist of molecules that occupy negligible space and have negligible forces between them. All collisions made between molecules ...
James Clerk Maxwell
(1831–79)British physicist, born in Edinburgh, who held academic posts at Aberdeen, London, and Cambridge. In the 1860s he was one of the founders of the kinetic theory of gases, but his best-known ...
Josiah Willard Gibbs
(1839–1903) US mathematician and physicist,who spent his entire academic career at Yale University. During the 1870s he developed the theory of chemical thermodynamics, devising functions such as ...
Lise Meitner
(1878–1968)Austrian-born Swedish physicist, discoverer with her nephew Otto Frisch of nuclear fission.The daughter of a lawyer, she became interested in physics when she was told as a small girl that ...
Max Planck
(1858–1947), German physicist and spokesman for science.Planck came from a family of lawyers and pastors. His marriage to the daughter of a banker placed him comfortably within the professional ...
Maxwell–Boltzmann distribution
A law describing the distribution of speeds among the molecules of a gas. In a system consisting of N molecules that are independent of each other except that they exchange energy on collision, it is ...
physical chemistry
The branch of chemistry concerned with the effect of chemical structure on physical properties. It includes chemical thermodynamics and electrochemistry.
probability
A numerical value given to the expectation that a particular event will occur. Although in scientific usage it is normally reckoned on a scale of 0 (for impossibility) to 1 (certainty), in forecasts ...
quantum theory
A theory of physics in which energy exists only in discrete quantities, called quanta. It was originated in 1900 by the German physicist Max Karl Ernst Ludwig Planck (1858–1947), who suggested that ...
