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According to quantum mechanics, the vacuum is not empty, but teeming with virtual particles that constantly wink in and out of existence. One strange consequence of this sea of activity is the Casimir effect: Two flat metal surfaces automatically attract one another if they get close enough.

Energy exist in empty space due to Heisenberg's time-energy version of uncertainty principle, and sometimes this energy is used to make virtual particle pair. Does the opposite also happen? That a particle disappears and reappears?

I don't think its possible for a single particle with spin or charge because it will violate conservation of charge/spin etc and if we are talking about 2 particles with opposite charge and opposite spin (antiparticles) its well known that they annihilate isn't that the same?

Buzz
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Shaurya Kad
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1 Answers1

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"Virtual particles" are mostly an artifact of applying perturbation theory. The question John Rennie linked has some excellent answers detailing this. As to your actual question: There are indeed diagrams arising which contain particles disappearing and then reappearing. Consider the contribution to the photon self-energy at one loop:one-loop contribution to the photon self energy In this specific diagram, the process is mediated by a quark-antiquark pair, but any charged particle/antiparticle pair can in principle take its place. If you will, this involves the photon "disappearing" and then "reappearing". In a theory that allows for vertices at which three lines meet, one could in principle even get the following disconnected diagram: An ingoing external leg terminates at a vertex that has an internal line which loops back to the same vertex, and then another loop connected to an outgoing external leg in the same fashion. I suppose this would truly mean that the particle "disappears" and then "reappears". However, such diagrams have vanishing vacuum expectation values and do not contribute to experimentally observed quantities.

paulina
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