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Is empty space 'empty'? Fields extend throughout all space. So photons moving through space 'know' about other fields (like the e⁻ field) This 'knowing' is called field interaction, & the leading order correction to the vacuum in E&M is a virtual electron, anti-electron pairpic.twitter.com/1wFEus8KB0
In Quantum Field Theory, 'classical' empty space is the lowest order term in the expansion of the full vacuum A photon in 'classical' empty space will propagate with no interactions Saying 'empty space is not empty' is just to say that the quantum 'loop' corrections are nonzeropic.twitter.com/iY12RonriR
In Quantum Field Theory, the intermediate particles of a Feynman diagram are referred to as 'virtual' particles A 'Loop' in a Feynman diagram (like the fermion loop shown here) represent purely quantum effects
Thanks to @SILENCEnwp for asking this question on Patreon!https://www.patreon.com/inertialobserver …
Currently working on a Feynman Diagram module for @3blue1brown’s graphics engine
Hope it’ll be useful to some of you!
I’m aroused.
Who wouldn’t be
Isn't in QFT, the "classical" vacuum just the ground state in Hilbertspace of the Hamiltonian constructed from the fields with all interactions higher than quadratic set to zero? (I wish I understood that Hilbert space with an action of fields concretely, say as some L_2)
These operators always exist in any Poincare-invariant QFT. In an interacting gapped QFT, we say the vacuum has "virtual" particles because the Hamiltonian now doesn't commute at different times but we still require the vacuum to have a zero energy eigenvalue.
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