Program
9:30 – 10:30: John DeBrota (with C. List): “A Heptalemma for Quantum Mechanics”
Coffee break
11:00 – 12:00: Daniele Oriti: “The classical gravitational case for relational realism”
12:00 – 13:00: Guido Bacciagaluppi: “Locality, retrocausality and signalling”
Lunch break
14:30 – 15:30: Alyssa Ney: “Branching (Almost) Everywhere and All at Once”
Short coffee break
15:45 – 16:45: Wayne Myrvold: “A New Argument for Gravitationally Induced Collapse”
Short coffee break
17:00 – 18:00: Huw Price: “Are Bell Correlations Selection Bias?”
18:00 – 19:00: Concluding discussion with comments by Beatrice Nettuno & Dan Marshall
Abstracts
Guido Bacciagaluppi: “Locality, retrocausality and signalling”
(https://arxiv.org/pdf/2602.11300)
As argued by several authors, violations of Measurement Independence (MI) provide a possible avenue for explaining the results of Bell experiments in a local way, specifically by invoking a form of zig-zag causation: retrocausation from Alice and Bob’s measurement settings to the source, and standard causation from the source to their measurement outcomes. In recent work with R. Hermens and G. Leegwater, we have formulated criteria under which violations of MI can in fact lead to signalling in an EPR-Bell scenario, and we have extended the analysis of Bell’s theorem to include also such violations of MI. In this talk, I shall present these results and analyse how this form of signalling based on zig-zag causation remains compatible with relativity.
John DeBrota & Christian List: “A Heptalemma for Quantum Mechanics”
(https://doi.org/10.1007/s10701-026-00919-9)
We present a seven-pronged no-go result for quantum mechanics: a “heptalemma”. It shows that seven initially plausible theses about physical reality are jointly inconsistent with the predictions of quantum mechanics, while any six are jointly consistent. We must then decide which theses to retain and which to give up. Since different interpretations of quantum mechanics entail different responses to the heptalemma, we get a novel taxonomy of such interpretations. Beyond the application to quantum mechanics, the heptalemma offers a general diagnostic criterion for determining whether a given scientific domain should count as classical or not, and if not, how it departs from classicality.
Wayne Myrvold: “A New Argument for Gravitationally Induced Collapse”
Despite some of the folklore in the philosophical literature, Bell’s theorem does not prove the impossibility of a dynamical collapse theory that is compatible with relativity, one that is, in Bell’s words, “Lorentz invariant, not just for all practical purposes but deeply, in the sense of Einstein, eliminating entirely any privileged reference system from the theory.” Indeed, relativistic collapse theories have been formulated by Bedingham and Pearle. In this talk, I will outline a framework for such theories, and discuss the ontology appropriate for them. There are two sorts of demands one might place on a relativistic theory. One is respecting relativistic causal structure, that is, eschewing cause-effect relations between spacelike separated events. The other is respecting the full symmetries of Minkowski spacetime. Perhaps counterintuitively, the latter is more difficult than the former. This suggests that we take advantage of the fact that we do not live in Minkowski spacetime, but a curved spacetime that is rich with local inhomogeneities, and couple collapse to spacetime curvature, as suggested by Diósi and Penrose, many years ago.
Alyssa Ney: “Branching (Almost) Everywhere and All at Once”
(https://philpapers.org/archive/NEYBEA.pdf)
Abstract: It is sometimes said that a strong reason to prefer the many worlds interpretation of quantum mechanics (MWI) over rival realist interpretations (such as hidden variables and collapse theories) is that by adopting the MWI, one can avoid the kind of “spooky action at a distance” that is supposed to follow as a consequence of quantum entanglement according to these other approaches. There is a straightforward argument that allows one to see this virtue of MWI (see Ney 2025), however some argue that for the MWI to be local, the branching process itself must be interpreted as local (Wallace 2012, Blackshaw, Huggett, and Ladyman 2026). My aim in this paper is to show why we should not adopt the local branching view. We don’t need branching to be local to make quantum mechanics compatible with special relativity. Moreover, the right way to conceive of branching in the MWI, given the highly influential functionalist analysis of worlds, requires it to be a global and instantaneous event and not a local, causal process.
Daniele Oriti: “The classical gravitational case for relational realism”
I summarize the role and implications of diffeomorphism symmetry and general covariance in classical gravitational theories, and the issue of defining invariant local observables, i.e. those with a local spacetime interpretation. I emphasize how the relational strategy to tackle this issue naturally leads to a relational or perspectival understanding of spacetime theories (and of spacetime itself), raising the further issue of understanding the mapping the different perspectives associated to different physical frames. I argue that this grounds a natural inclination toward relational or perspectival forms of realism also in the context of quantum mechanics. I conclude by pointing out the further, genuinely novel aspects of quantum mechanics that classical relationalism does not suffice to resolve, and that require truly novel conceptual work, even when starting from the standpoint of relational/perspectival realism.
Huw Price: “Are Bell Correlations Selection Bias?”
(https://arxiv.org/pdf/2605.00406)
Abstract: Selection artefacts are common in science. Methods of selecting samples from larger populations may produce bias, in either direction. They may induce correlations between variables independent in a full population, or mask correlations between variables dependent in a full population. Here we offer a novel application of these familiar ideas. We show that they are relevant to puzzling correlations uncovered in quantum theory by John Stewart Bell (Bell 1964). In the light of Bell’s work and subsequent experiments it is widely believed that the quantum world is ‘nonlocal’, in apparent tension with relativity. Many hold that the only alternative is to abandon ‘realism’, the view that there is an objective world independent of measurement. We propose instead that Bell correlations are selection artefacts, in tension neither with relativity nor realism.
Organizer
Christian List
John DeBrota
Bianca Scheeff
Registration
Please register by sending an email to office.list@lrz.uni-muenchen.de