Poissonian Spontaneous Localization: A new model for spontaneous collapse and hybrid classical-quantum gravity

Spontaneous collapse models modify quantum dynamics to solve the measurement problem via small violations of unitarity, entailing effects such as spatial decoherence and heating. This makes them empirically testable. After briefly recalling the logic and phenomenology of standard collapse models (GRW, CSL, and DP), I will present an alternative: Poissonian Spontaneous Localization (PSL). The construction is based on “collapse points” distributed in spacetime via a Poisson sprinkling and it can reproduce CSL-like master equations in an appropriate limit while keeping a clear physical interpretation in terms of localized collapse events. Notably, according to comparison with current experimental data, PSL shows much greater resilience to experimental falsification than standard collapse models. I will then discuss a gravitational extension, Gravitational PSL (GPSL), where classical Newtonian gravity is sourced by the stochastic dynamics. Compared to other hybrid models, this yields distinctive features such as a stable gravitational vacuum and a short-range gravitational back-reaction noise. I will also discuss the spontaneous heating rate of GPSL, and the related current experimental constraints derived from comparison with neutron stars data. I will close the seminar by outlining open directions, including non-Markovian and relativistic generalizations.