Lugano Philosophy Colloquia. Giovanni Valente

On Thursday, May 21 at 5.00pm (CET), Room Multiuso FTL Building (USI west campus)
Giovanni Valente (Politecnico di Milano)

Approximations that matter: virtual particles as carriers of interactions

Abstract: In this talk, based on joint work with Nicolò Cangiotti and Gianni Arioli, I will develop an indispensability argument in support of the existence of virtual particles in scattering processes. In order to avoid the Paradox of Infinite Limits, which allegedly poses a challenge to scientific realism, one needs to de-idealize the fictitious systems introduced by the two limiting procedures employed in the perturbation scheme, namely the infinite expansion in Dyson series and the limits for negative and positive infinite times associated with the assumption of free particles. I will show that these limits do not introduce essential idealizations, in agreement with scientific realism. What is more, according to our argument, unobservable virtual particles arise as essential approximations and they should be interpreted as propagators of the interaction responsible for subatomic scattering. As such, their existence is based on the use of approximations that matter.

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