Editing Kinetic theory of gases (section)

=== Kinetic theory of gases ===
[[File:Porträt des Daniel Bernoulli (cropped).jpg|thumb|167x167px|Daniel Bernoulli]]
[[Image:HYDRODYNAMICA, Danielis Bernoulli.png|thumb|upright|''Hydrodynamica'' front cover]]

In 1738 [[Daniel Bernoulli]] published ''[[Hydrodynamica]]'', which laid the basis for the [[Kinetic energy|kinetic]] theory of [[gas]]es. In this work, Bernoulli posited the argument, that gases consist of great numbers of molecules moving in all directions, that their impact on a surface causes the pressure of the gas, and that their average [[kinetic energy]] determines the temperature of the gas. The theory was not immediately accepted, in part because [[conservation of energy]] had not yet been established, and it was not obvious to [[physicist]]s how the collisions between molecules could be perfectly elastic.<ref name="PonomarevKurchatov1993">{{cite book|title=The Quantum Dice|author1=L.I Ponomarev|author2=I.V Kurchatov|date=1 January 1993|publisher=CRC Press|isbn=978-0-7503-0251-7}}</ref>{{rp|36–37}}

Pioneers of the kinetic theory, whose work was also largely neglected by their contemporaries, were Mikhail Lomonosov (1747),<ref>Lomonosov 1758</ref> [[Georges-Louis Le Sage]] (ca. 1780, published 1818),<ref>Le Sage 1780/1818</ref> [[John Herapath]] (1816)<ref>Herapath 1816, 1821</ref> and [[John James Waterston]] (1843),<ref>Waterston 1843</ref> which connected their research with the development of [[mechanical explanations of gravitation]].

In 1856 [[August Krönig]] created a simple gas-kinetic model, which only considered the [[Translation (geometry)|translational motion]] of the particles.<ref>Krönig 1856</ref> In 1857 [[Rudolf Clausius]] developed a similar, but more sophisticated version of the theory, which included translational and, contrary to Krönig, also [[rotation]]al and vibrational molecular motions. In this same work he introduced the concept of [[mean free path]] of a particle.<ref>Clausius 1857</ref> In 1859, after reading a paper about the [[diffusion]] of molecules by Clausius, Scottish physicist [[James Clerk Maxwell]] formulated the [[Maxwell distribution]] of molecular velocities, which gave the proportion of molecules having a certain velocity in a specific range.<ref>See:
* Maxwell, J.C. (1860) [https://books.google.com/books?id=-YU7AQAAMAAJ&pg=PA19 "Illustrations of the dynamical theory of gases. Part I. On the motions and collisions of perfectly elastic spheres,"] ''Philosophical Magazine'', 4th series, '''19''' : 19–32.
* Maxwell, J.C. (1860) [https://books.google.com/books?id=DIc7AQAAMAAJ&pg=PA21 "Illustrations of the dynamical theory of gases. Part II. On the process of diffusion of two or more kinds of moving particles among one another,"] ''Philosophical Magazine'', 4th series, '''20''' : 21–37.</ref> This was the first-ever statistical law in physics.<ref>{{cite book|title=The Man Who Changed Everything – the Life of James Clerk Maxwell|author=Mahon, Basil|publisher=Wiley|year=2003|isbn=0-470-86171-1|location=Hoboken, NJ|oclc=52358254}}</ref> Maxwell also gave the first mechanical argument that molecular collisions entail an equalization of temperatures and hence a tendency towards equilibrium.<ref>{{Cite journal|last1=Gyenis|first1=Balazs|year=2017|title=Maxwell and the normal distribution: A colored story of probability, independence, and tendency towards equilibrium|journal=Studies in History and Philosophy of Modern Physics|volume=57|pages=53–65|arxiv=1702.01411|bibcode=2017SHPMP..57...53G|doi=10.1016/j.shpsb.2017.01.001|s2cid=38272381}}</ref> In his 1873 thirteen page article 'Molecules', Maxwell states: "we are told that an 'atom' is a material point, invested and surrounded by 'potential forces' and that when 'flying molecules' strike against a solid body in constant succession it causes what is called [[pressure]] of air and other gases."<ref>Maxwell 1873</ref>
In 1871, [[Ludwig Boltzmann]] generalized Maxwell's achievement and formulated the [[Maxwell–Boltzmann distribution]]. The [[logarithm]]ic connection between [[entropy]] and [[probability]] was also first stated by Boltzmann.

At the beginning of the 20th century, atoms were considered by many physicists to be purely hypothetical constructs, rather than real objects. An important turning point was [[Albert Einstein]]'s (1905)<ref>Einstein 1905</ref> and [[Marian Smoluchowski]]'s (1906)<ref>Smoluchowski 1906</ref> papers on [[Brownian motion]], which succeeded in making certain accurate quantitative predictions based on the kinetic theory.

Following the development of the [[Boltzmann equation]], a framework for its use in developing transport equations was developed independently by [[David Enskog]] and [[Sydney Chapman (mathematician)|Sydney Chapman]] in 1917 and 1916. The framework provided a route to prediction of the transport properties of dilute gases, and became known as [[Chapman–Enskog theory]]. The framework was gradually expanded throughout the following century, eventually becoming a route to prediction of transport properties in real, dense gases.