vacuum approximation

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• Vacuum — This article is about empty physical space or the absence of matter. For other uses, see Vacuum (disambiguation). Free space redirects here. For other uses, see Free space (disambiguation). Pump to demonstrate vacuum In everyday usage, vacuum is… …   Wikipedia

• QCD vacuum — The QCD vacuum is the vacuum state of quantum chromodynamics (QCD). It is an example of a non perturbative vacuum state, characterized by many non vanishing condensates such as the gluon condensate or the quark condensate. These condensates… …   Wikipedia

• Born-Oppenheimer approximation — In quantum chemistry, the computation of the energy and wavefunction of an average size molecule is a formidable task that is alleviated by the Born Oppenheimer (BO) approximation. For instance the benzene molecule consists of 12 nuclei and 42… …   Wikipedia

• False vacuum — In quantum field theory, a false vacuum is a metastable sector of space that appears to be a perturbative vacuum, but is unstable due to instanton effects that may tunnel to a lower energy state. This tunneling can be caused by quantum… …   Wikipedia

• Polarizable vacuum — In theoretical physics, particularly fringe physics, polarizable vacuum (PV) most often refers to a proposal by Harold Puthoff to develop an analogue of general relativity to describe gravity in optics like terms. Puthoff himself has apparently… …   Wikipedia

• Field electron emission — It is requested that a diagram or diagrams be included in this article to improve its quality. For more information, refer to discussion on this page and/or the listing at Wikipedia:Requested images. Field emission (FE) (also known as field… …   Wikipedia

• General relativity — For a generally accessible and less technical introduction to the topic, see Introduction to general relativity. General relativity Introduction Mathematical formulation Resources …   Wikipedia

• radiation — radiational, adj. /ray dee ay sheuhn/, n. 1. Physics. a. the process in which energy is emitted as particles or waves. b. the complete process in which energy is emitted by one body, transmitted through an intervening medium or space, and… …   Universalium

• Feynman diagram — The Wick s expansion of the integrand gives (among others) the following termNarpsi(x)gamma^mupsi(x)arpsi(x )gamma^ upsi(x )underline{A mu(x)A u(x )};,whereunderline{A mu(x)A u(x )}=int{d^4pover(2pi)^4}{ig {mu u}over k^2+i0}e^{ k(x x )}is the… …   Wikipedia

• Pi — This article is about the number. For the Greek letter, see Pi (letter). For other uses, see Pi (disambiguation). The circumference of a ci …   Wikipedia

• Einstein field equations — General relativity Introduction Mathematical formulation Resources Fundamental concepts …   Wikipedia