| Abstract: Does textbook quantum theory suffer from fundamental inconsistencies, like the measurement problem, or do phenomena like decoherence save the day? I will make the case that the problems with the textbook theory are real and significant, and that efforts to address them have produced many practical spin-offs, including decoherence itself. I will then lay out a minimal set of criteria that any consistent axiomatic formulation of quantum theory should satisfy. I will argue that none of the existing options, including the Many Worlds interpretation, clear this bar, so another approach to quantum foundations is urgently needed. I will introduce one new such approach, based on a remarkably simple axiomatic picture in which every system has an old-fashioned configuration in physical space that evolves according to an “indivisible” stochastic process, and in which wave functions and superposition are no longer literal ingredients of reality. I will also present a mathematical mapping between these stochastic processes and the usual Hilbert-space formulation of quantum theory. After describing this stochastic-quantum correspondence, and going through several concrete examples, I will turn to a careful dissection of Bell's theorem, and show how “indivisible quantum theory” points to shortcomings in the theorem's claims about local causality. I will conclude with several intriguing possible applications to physics and to other areas of science.
References: https://arxiv.org/abs/2302.10778, https://arxiv.org/abs/2402.16935. |