Upcoming talks
10 January 2026
Mahmoud Jalloh (Caltech), “Constants of Nature, Law Construal, and Theory Individuation“
The debate regarding whether physics requires absolute or merely comparative quantitative structure has surfaced a question regarding the nomological status of the constants: Are their magnitudes necessary or contingent? I argue here that this is merely a special case of a more general question: To what fineness of grain ought we construe the laws? Answering this question requires balancing the epistemic significance of the laws with the robustness of our standards for individuating theories. It is found that a relatively coarse-grained construal of the laws, making the constants nomologically contingent, best balances these considerations in a manner. To show this, a methodological primitivism is adopted, such that the laws are considered as equations, with differing degrees of structure. The interpretative equilibrium found construes the laws to have algebraic and polarity structure, but not magnitude structure. Not only is this of general significance for accounts of the laws of nature, but it also provides the contingentist comparativist an answer to accusations of fallacious theory equivocation.
Please read Mahmoud’s preprint prior to the meeting.
Past talks
25 October 2025
Eddy Chen (UCSD), “Typical Quantum States of the Universe are Observationally Indistinguishable”
(Joint work with Roderich Tumulka) We establish three new impossibility results regarding our knowledge of the quantum state of the universe — a central object in quantum theory. We show that, if the universal quantum state is a typical unit vector from a high-dimensional subspace H_0 of Hilbert space H (such as the one defined by a low-entropy macro-state as prescribed by the Past Hypothesis), then no observation can determine or just significantly narrow down which vector it is. In other words, the overwhelming majority of possible state vectors are observationally indistinguishable from each other (and from the density matrix of H_0). Moreover, we show that for any observation that isn’t too unlikely and most pairs of unit vectors from H_0, the observation will not significantly favor one vector over the other. We further show that the uniform distribution over the unit sphere in H_0, after Bayesian updating in the light of any observation that isn’t too unlikely, is still extremely close to uniform. Our arguments rely on a typicality theorem from quantum statistical mechanics. We also discuss how theoretical considerations beyond empirical evidence might inform our understanding of this fact and our knowledge of the universal quantum state.
Participants can read a pre-print of this work here: https://arxiv.org/abs/2410.16860
10 January 2026, Mahmoud Jalloh (Caltech)
7 February 2026, Ellen Shi (UC Irvine / UC Berkeley)
7 March 2026, Porter Williams (Pittsburgh)
4 April 2026, James Read (Oxford)
16 May 2026, Chris Smeenk (Western / UCLA)
