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
Vacuum energy — is an underlying background energy that exists in space even when devoid of matter (known as free space). The vacuum energy is deduced from the concept of virtual particles, which is itself derived from the energy time uncertainty principle. Its… … Wikipedia
Vacuum state — In quantum field theory, the vacuum state (also called the vacuum) is the quantum state with the lowest possible energy. Generally, it contains no physical particles. The term zero point field is sometimes used as a synonym for the vacuum state… … Wikipedia
Vacuum expectation value — Quantum field theory (Feynman diagram) … Wikipedia
Vacuum polarization — In quantum field theory, and specifically quantum electrodynamics, vacuum polarization describes a process in which a background electromagnetic field produces virtual electron positron pairs that change the distribution of charges and currents… … Wikipedia
Vacuum permeability — This article is about the magnetic constant. For the analogous electric constant, see vacuum permittivity. Vacuum permeability, permeability of free space, or magnetic constant is an ideal, (baseline) physical constant, which is the value of… … Wikipedia
Theory of relativity — This article is about the scientific concept. For philosophical or sociological theories about relativity, see Relativism. For the silent film, see The Einstein Theory of Relativity. Two dimensional projection of a three dimensional analogy of… … Wikipedia
Theory of impetus — The theory of impetus was an antiquated auxiliary or secondary theory of Aristotelian dynamics, put forth initially to explain projectile motion against gravity. It was first introduced by Hipparchus in antiquity, and subsequently further… … Wikipedia
Vacuum tube — This article is about the electronic device. For experiments in an evacuated pipe, see free fall. For the transport system, see pneumatic tube. Modern vacuum tubes, mostly miniature style In electronics, a vacuum tube, electron tube (in North… … Wikipedia
Vacuum solution (general relativity) — In general relativity, a vacuum solution is a Lorentzian manifold whose Einstein tensor vanishes identically. According to the Einstein field equation, this means that the stress energy tensor also vanishes identically, so that no matter or non… … Wikipedia