The equipartition theorem is a formula from statistical mechanics that relates the temperature of a system with its average energies. The original idea of equipartition was that, in thermal equilibrium, energy is shared equally among its various forms; for example, the average kinetic energy in the translational motion of a molecule should equal the average kinetic energy in its rotational motion. Like the virial theorem, the equipartition theorem gives the total average kinetic and potential energies for a system at a given temperature, from which the system's heat capacity can be computed. However, equipartition also gives the average values of individual components of the energy. It can be applied to any classical system in thermal equilibrium, no matter how complicated. The equipartition theorem can be used to derive the classical ideal gas law, and the Dulong–Petit law for the specific heat capacities of solids. It can also be used to predict the properties of stars, even white dwarfs and neutron stars, since it holds even when relativistic effects are considered. Although the equipartition theorem makes very accurate predictions in certain conditions, it becomes inaccurate when quantum effects are significant, namely at low enough temperatures.

Read the rest of this article:
http://en.wikipedia.org/wiki/Equipartition_theorem

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Today's selected anniversaries:

69:

Vespasian became the fourth Roman Emperor in the Year of the Four Emperors.
(http://en.wikipedia.org/wiki/Year_of_the_Four_Emperors)

1844:

The Rochdale Pioneers, usually considered the first successful cooperative enterprise, opened their store in Rochdale, England, and formed the basis for the modern cooperative movement.
(http://en.wikipedia.org/wiki/Rochdale_Pioneers)

1937:

The animated feature film Snow White and the Seven Dwarfs, based on the fairy tale Snow White by the Brothers Grimm, premiered to a widely receptive audience.
(http://en.wikipedia.org/wiki/Snow_White_and_the_Seven_Dwarfs_(1937_film))

1962:

Rondane National Park, Norway's first national park, was established.
(http://en.wikipedia.org/wiki/Rondane_National_Park)

1988:

Pan Am Flight 103: A Libyan government sponsored terrorist bomb exploded and destroyed a Boeing 747 in flight over Lockerbie, Scotland, killing 270, including 11 on the ground.
(http://en.wikipedia.org/wiki/Pan_Am_Flight_103)

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Wiktionary's word of the day:

sheepishly   (adv)  Meekly; self-consciously; with embarrassment.
(http://en.wiktionary.org/wiki/sheepishly)

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Wikiquote quote of the day:

If there is a God, I don't think He would demand that anyone bow down or stand up to Him. I often have a suspicion that God is still trying to work things out and hasn't finished.
--Rebecca West
(http://en.wikiquote.org/wiki/Rebecca_West)