Editing History of physics (section)

===Statistical mechanics (a fundamentally new approach to science)===
[[File:James Clerk Maxwell.png|thumb|upright|[[James Clerk Maxwell]] (1831–1879)]]
{{further|History of statistical mechanics}}
In 1860, [[James Clerk Maxwell]] worked out the mathematics of the distribution of velocities of the molecules of a gas, known today as the [[Maxwell-Boltzmann distribution]].

The atomic theory of matter had been proposed again in the early 19th century by the chemist [[John Dalton]] and became one of the hypotheses of the kinetic-molecular theory of gases developed by Clausius and James Clerk Maxwell to explain the laws of thermodynamics.
[[File:Boltzmann2.jpg|thumb|upright|[[Ludwig Boltzmann]] (1844–1906)]]

The kinetic theory in turn led to a revolutionary approach to science, the [[statistical mechanics]] of [[Ludwig Boltzmann]] (1844–1906) and [[Josiah Willard Gibbs]] (1839–1903), which studies the statistics of microstates of a system and uses statistics to determine the state of a physical system. Interrelating the statistical likelihood of certain states of organization of these particles with the energy of those states, Clausius reinterpreted the dissipation of energy to be the statistical tendency of molecular configurations to pass toward increasingly likely, increasingly disorganized states (coining the term "[[entropy]]" to describe the disorganization of a state). The statistical versus absolute interpretations of the second law of thermodynamics set up a dispute that would last for several decades (producing arguments such as "[[Maxwell's demon]]"), and that would not be held to be definitively resolved until the behavior of atoms was firmly established in the early 20th century.<ref>{{Harvtxt|Smith|Wise|1989}}</ref><ref>{{Harvtxt|Smith|1998}}</ref> In 1902, [[James Jeans]] found the length scale required for gravitational perturbations to grow in a static nearly homogeneous medium.