This post offers a paper a wrote a few years ago for a workshop in beautiful Buenos Aires in which we explored the puzzle of distinguishability and indistinguishability in physics. Under what conditions can we consider physical objects distinguishable, and when must we assume they are indistinguishable? It turns out that a somewhat obscure quantity … Continue reading Fun with the chemical potential: an exploration of the quantum/classical divide →

This animation is based on my publication Maxwell's Demon Is Foiled by the Entropy Cost of Measurement, Not Erasure, https://www.mdpi.com/2673-9321/5/2/16 (preprint version: https://philsci-archive.pitt.edu/25388/) https://videopress.com/v/WqIS0pYm?resizeToParent=true&cover=true&preloadContent=metadata&useAverageColor=true The Demon gets ready to violate the 2nd Law, but is in for a surprise!

This is a presentation I gave at a 2021 workshop on Identity and Indistinguishability in quantum systems. (The paper based on this talk appears in this publication: "Quantum Haecceity," Phil. Trans. R. Soc. A. 3812022010620220106. http://doi.org/10.1098/rsta.2022.0106 (2023), available as a preprint here: https://arxiv.org/abs/2301.00502). My talk includes a specific scattering example (electron repulsion) in which there … Continue reading Presentation in 2021: critique of the conventional claim that symmetrized quantum states are about “redundancy of description” →

This paper shows that once we take into account that gas molecules are quantum systems, we find that there is an entropy cost to measuring their positions, and that this is what prevents a Maxwell's Demon from violating the second law of thermodynamics. The tradition of taking "memory erasure" (originated by Bennett and Landauer) as … Continue reading Maxwell’s Demon is Foiled by Measurement, Not By Memory Erasure. →

I continue to get claims that the Transactional Formulation of quantum mechanics (now called RTI) isn't really a "theory" because it doesn't lead to "empirically testable differences" from conventional quantum theory. So I thought I'd share an email reply to someone who recently made this claim: But RTI does lead to empirically testable differences with … Continue reading RTI is a different theory from conventional quantum mechanics; it passes empirical tests routinely failed by the conventional theory →

There has recently been renewed discussion of an experiment involving nested interferometers (presented by Danan et al, 2013). This experiment has been used by those authors (and others) to argue for the correctnesss of a formulation of quantum theory known as the "Two State Vector Formalism: (TSVF). In this paper, I take a close look … Continue reading Where Photons Have Been: nowhere without all of their wavefunctions →

This is a paper that I presented at a 2024 conference in honor of author Iain McGilchrist at the Center for Process Studies in San Francisco. It argues that the Western intellectual tradition, despite its many accomplishments, is critically deficient not only in modes of thought naturally associated with the brain's right hemisphere but also … Continue reading The Quantum Master and its Classical Emissary →

In this post, I offer a (hopefully) user-friendly conceptual introduction to gravitation as an entropic force, from the perspective of the transactional formulation. This account departs somewhat from traditional presentations of entropic gravity and the holographic principle by insisting that "information" alone is not physically sufficient to define thermodynamic entropy. Entropy must always be defined … Continue reading Entropic Force and Gravitation →

I previously posted a draft version of a paper pointing out that "Relational Quantum Mechanics" (RQM), an interpretation proposed by C. Rovelli, is faced with serious, arguably fatal problems. That paper has gone through the review process for the journal Philosophy of Physics and is now provisionally accepted (pending minor revisions). Here is the final … Continue reading Forthcoming in Philosophy of Physics: “Relational Quantum Mechanics” is fatally flawed. →

The authors have attempted to save "Relational Quantum Theory" from the well-known inconsistency problems of conventional quantum theory. I argue that they fail rather spectacularly. Comments welcome: https://philsci-archive.pitt.edu/23634/