View source for Vacuum (disambiguation)

{{disambig}}

{{r|Vacuum (partial)}} The term ''partial vacuum'' refers to real vacuums which can be obtained and observed.
{{r|Vacuum (quantum electrodynamic)}} The term ''quantum electrodynamic vacuum'', or QED, refers to refers to the ground state of the [[Electromagnetic wave|electromagnetic field]], which is subject to fluctuations about a dormant zero average-field condition.
{{r|Vacuum (partial)}} The term ''partial vacuum'' refers to real vacuums which can be obtained and observed.
{{r|Vacuum (classical)}} The term classical vacuum refers to a perfect vacuum (or [[free space (electromagnetism)|free space]]) that is completely empty of matter having a gaseous pressure of exactly zero; as zero pressure cannot be attained in practice, this situation an idealization useful as a reference state, but is not realizable.