Virtual States

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Virtual States


in quantum theory, short-lived inter-mediate states of a microsystem in which the usual link between the energy, momentum, and mass of the system is disrupted. The average lifetime of virtual states is on the order of h/Δδ, where Δδ is the deviation of the energy δ from its value as determined by the relations δ= p2/2m0 in nonrelativistic theory and δ2 = c2p2+c4m20 in relativistic theory, p is the momentum, m0 is the mass of the system, c is the speed of light, and h is Planck’s constant divided by .

The most important particular case of virtual states is the state of one or more virtual particles. Virtual states usually arise as intermediate states upon the collision of microscopic particles. For example, the collision of neutrons with protons at energies of up to 10-20 mega electron volts takes place essentially by means of the formation and rapid decay of a deuteron in a virtual state.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
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