In quantum field theory, the quantum vacuum state (also called the quantum vacuum or vacuum state) is the quantum state with the lowest possible energy. Generally, it contains no physical particles. However, the quantum vacuum is not a simple empty space,[1][2] but instead contains fleeting electromagnetic waves and particles that pop into and out of the quantum field.[3][4][5]
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For a historical discussion, see for example Ari Ben-Menaḥem, ed. (2009). "Quantum electrodynamics (QED)". Historical Encyclopedia of Natural and Mathematical Sciences. Vol. 1 (5th ed.). Springer. pp. 4892 ff. ISBN978-3-540-68831-0. For the Nobel prize details and the Nobel lectures by these authors, see "The Nobel Prize in Physics 1965". Nobelprize.org. Retrieved 2012-02-06.