General Information

This group is a forum for philosophers (faculty members and graduate students) in Southern California to meet and discuss their own research and other recent articles in philosophy of physics. We intend to meet 2-3 times per quarter, with topics determined by the interests of the group.

Unless otherwise noted, meetings will be hosted by the LPS department at UC Irvine, in the LPS seminar room (777 Social Science Tower) [campus map]. For instructions regarding parking and to reserve a permit, contact Patty Jones, LPS Department Manager.

Please contact me (james.owen.weatherall [AT] uci [DOT] edu) if you would like to join the group.


Upcoming Talks:

11 December 2022

Eddy Keming Chen (UC San Diego), “The Wentaculus: Density Matrix Realism Meets the Arrow of Time

Two of the most difficult problems in the foundations of physics are (1) what gives rise to the arrow of time and (2) what the ontology of quantum mechanics is. They are difficult because the fundamental dynamical laws of physics do not pick out an arrow of time, and the quantum-mechanical wave function describes a high-dimensional reality that is dramatically different from the objects of our ordinary experiences. In this talk, I propose a unified solution by adopting a new theory of time’s arrow in a quantum universe—the Wentaculus [1-3]. Central to my solution are (i) Density Matrix Realism, the idea that the quantum state of the universe is objective but impure, and (ii) the Initial Projection Hypothesis, a new candidate law of nature that selects a unique initial quantum state. On the Wentaculus, the initial quantum state of the universe is sufficiently simple to be a law, and the arrow of time can be traced back to an exact boundary condition. As a bonus, we can use the theory to realize “strong determinism” as defined by Penrose [6] and remove the “fundamental nomic vagueness” of the Past Hypothesis as defined by Chen [4]. I end with some open problems for future research. 

The presentation will be self-contained, but here are some optional background readings for those interested: 
[1] Chen, E.K., Quantum Mechanics in a Time-Asymmetric Universe: On the Nature of the Initial Quantum StateThe British Journal for the Philosophy of Science, 2018 
[2] Chen, E.K., Time’s Arrow in a Quantum Universe: On the Status of Statistical Mechanical Probabilities in Valia Allori (ed.), Statistical Mechanics and Scientific Explanation: Determinism, Indeterminism and Laws of Nature, World Scientific, 2020
[3] Chen, E.K., From Time Asymmetry to Quantum Entanglement: The Humean UnificationNoûs, 2020
[4] Chen, E.K., Fundamental Nomic VaguenessThe Philosophical Review, forthcoming
[5] Chen, E.K., The Past Hypothesis and the Nature of Physical Laws in Barry Loewer, Eric Winsberg, and Brad Weslake (eds.), Time’s Arrows and the Probability Structure of the World, Harvard University Press, forthcoming
[6] Penrose, R. The Emperor’s New Mind: Concerning Computers, Minds and The Laws of Physics, Oxford University Press, 1989, p.560 [Oxford Scholarship Online]

6 November 2021, 3pm, 777 Social Science Tower, UC Irvine

Chip Sebens (Caltech), “The Fundamentality of Fields”

There is debate as to whether quantum field theory is, at bottom, a quantum theory of fields or particles.  One can take a field approach to the theory, using wave functionals over field configurations, or a particle approach, using wave functions over particle configurations.  This article argues for a field approach, presenting three advantages over a particle approach: (1) photons cannot be treated as particles, (2) a classical field model of the electron is superior to a classical particle model (as regards both spin and self-interaction), and (3) field wave functionals can be used for interacting theories whereas particle wave functions cannot.  The article also describes three tasks facing proponents of a field approach: (1) legitimize or excise the use of Grassmann numbers for fermionic field values and wave functional amplitudes, (2) describe how quantum fields give rise to particle-like behavior, and (3) explain the absence of electron self-repulsion in quantum electrodynamics.

Please read Chip’s paper prior to the talk.

11 December 2021, 3pm, 777 Social Science Tower, UC Irvine

Eddy Chen (UCSD), TBD