On Tue, Aug 27, 2019 at 12:40 PM Jason Resch <[email protected]> wrote:
> On Mon, Aug 26, 2019 at 9:25 PM Bruce Kellett <[email protected]> > wrote: > >> On Tue, Aug 27, 2019 at 10:35 AM Jason Resch <[email protected]> >> wrote: >> >>> On Mon, Aug 26, 2019 at 7:32 PM Bruce Kellett <[email protected]> >>> wrote: >>> >>>> On Tue, Aug 27, 2019 at 10:27 AM Jason Resch <[email protected]> >>>> wrote: >>>> >>>>> These videos provide a good introduction: >>>>> >>>>> https://www.youtube.com/watch?v=X5rAGfjPSWE >>>>> https://www.youtube.com/watch?v=fG52mXN-uWI >>>>> >>>>> Virtual particles are the basis of all particle interactions in QED, >>>>> called the jewel of physics for having made the most accurate predictions >>>>> of any physical theory. >>>>> >>>> >>>> The trouble is that virtual particles are internal lines in Feynman >>>> diagrams, and the Feynman diagrams are formed as a perturbation expansion. >>>> They have to be summed to make contact with physical processes. This puts >>>> the status of virtual particles, as ontological entities, into considerable >>>> doubt. Ultimately, they are nothing but a calculational device, and quantum >>>> amplitudes can be evaluated without ever using Feynman diagrams, so virtual >>>> particles need never appear anywhere. >>>> >>>> >>> But this "calculational device" (funny how many things are mere devices) >>> predicts the lamb shift as well as the Casimir effect, to great accuracy. >>> >> >> No, virtual particles do not predict the Lamb shift -- they are just an >> aid to calculating terms in the perturbation expansion of the QED vertex >> function. >> >> > Is this answer in error? > https://physics.stackexchange.com/questions/443186/lamb-shift-and-virtual-particles > > No, that seems to give the standard Feynman diagrams for radiative corrections to the photon propagator. (I misremembered previously. Radiative corrections to the vertex function are important for the calculation of g-2 for the electron, not for the Lamb shift, which is a photon propagator correction.) But the standard calculation says nothing about reifying the internal lines in the diagrams. In fact, a good approximation to the Lamb shift can be obtained from a simple non-relativistic calculation that never mentions quantum fields, vacuum polarisation, or virtual particles. Aren't virtual particles necessary for explaining the limited range of the > strong force? > No. The uncertainty principle can do that. > And solving the blackhole information paradox? > No. There is no BH information paradox, and virtual particles are not necessary in order to understand Hawking radiation (despite what Hawking says in his popular accounts. His original paper on the matter does not use virtual loops. Not that these exist in the way described, anyway.) Bruce -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAFxXSLRP0-wN1UmZh2ivx-fPd9sLcB1dCbSNEdOJJy228WPmjQ%40mail.gmail.com.
