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If not, why do we include such a description for force interactions? It seems to me that physics implements virtual particles as a means to do calculations. If this is the case, what is the motivation in coming up with virtual particles that have properties that make little intuitive sense? Are there other ways to describe QFT without exchanging of virtual particles? From an outside perspective, it feels like when something is inferred from math, it can be described in more than one way. Thanks


marked as duplicate by John Rennie, CuriousOne, Martin, knzhou, Qmechanic Jun 9 '16 at 20:33

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    $\begingroup$ See, for instance, this question. $\endgroup$ – ACuriousMind Jun 6 '16 at 14:55
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    $\begingroup$ You are correct, virtual particles are only a calculation tool. Having said that, the calculated effects are perfectly real. If you look at perturbation theory in non-relativistic quantum mechanics, e.g. for atomic physics calculations, "virtual particles" are all over the place: they are the intermediate states that the formalism sums over. Are those states "real"? Yes, those degrees of freedom exist in the system. Can we detect the system going trough them? No. $\endgroup$ – CuriousOne Jun 6 '16 at 14:55
  • $\begingroup$ @CuriousOne What is the motivation for treating these interactions as the exchange of virtual particles, though? I suppose there is no right way, especially if they achieve the same result (describing reality correctly). However, are there hints pointing towards this description, or is it just a creative way to describe these interactions? $\endgroup$ – colour Jun 6 '16 at 14:59
  • $\begingroup$ If you look at the path integral formalism, virtual particles drop out of the math in a fairly straight forward way by approximating the kernel with an infinite series. As elegant as this looks, the devil is in the detail... a priory there is no justification for the convergence of this procedure and in cases of strong coupling it does, indeed, not converge. $\endgroup$ – CuriousOne Jun 6 '16 at 15:04
  • $\begingroup$ I would say virtual particles are real and are verified indirectly. The first experiment probing the effect of the interaction with virtual particles (electron-positron pair in this case), was the measurement of the Lamb shift in atomic hydrogen. $\endgroup$ – Paul Jun 6 '16 at 16:18