Philosophy of Physics

De-Idealizing De-Idealization: Beyond Full Reversal, forthcoming in the British Journal for the Philosophy of Science, with Eugene Y.S. Chua [Article]

• Abstract: There is a question of whether de-idealization is needed for justified use of -- for 'checking' -- idealizations. We argue that the standard philosophical account of de-idealization has become too idealized, but that this does not preclude the possibility of justificatory practices which show how models can be used to make inferences about the world. In turn, motivated by examples in physics, we provide a more expansive and practice-driven account of de-idealization by relaxing the standards for closeness to more realistic theoretical items, identifying at least three kinds of procedures for de-idealization: intra-model, inter-model, and measurement de-idealizations. These examples highlight how idealizations can be -- and indeed have been -- scrutinized within physics without appealing to the philosopher's idealized notion of de-idealization.

Axiomatization of Special Relativity in First Order Logic, in Communications in Theoretical Physics 66: 19-28 (2016), with Lei Chen, Wan-Ting He, Yong-Ge Ma, and Xin-Yu Zhang [Article]

• Abstract: The axiomatization of physical theories is a fundamental issue of science. The first-order axiomatic system SpecRel for special relativity proposed recently by Andréka et al. is not enough to explain all the main results in the theory, including the twin paradox and energy-mass relation. In this paper, from a four-dimensional spacetime perspective, we introduce the concepts of world-line, proper time and four-momentum to our axiomatic system SpecRel+. Then we introduce an axiom of mass (AxMass) and take four-momentum conservation as an axiom (AxCFM) in SpecRel+. It turns out that the twin paradox and energy-mass relation can be derived from SpecRel+ logically. Hence, as an extension of SpecRel, SpecRel+ is a suitable first-order axiomatic system to describe the kinematics and dynamics of special relativity.

A paper on black hole and universality explanation in science [Under Review]

• Draft available upon request.

• The title omitted to comply with the anonymity requirements of the peer review process.

A paper on black hole thermodynamics without event horizons [Under Review]

• Draft available upon request.

• The title omitted to comply with the anonymity requirements of the peer review process.

Reconstructing the Reality of Black Holes, with Niels Linnemann and Chris Smeenk [In Preparation]

• Abstract: We investigate the methodological foundations in classical black hole modeling, addressing the question of how our conceptualizations of black holes change from mathematical artifacts to physically genuine candidates for reality. For this, we review three approaches to modeling black holes that each involves a distinctive choice of specific mathematical tools: the exact solution approach, the topological-causal approach, and the initial-value approach. We argue that interplay among these approaches has been essential in driving an iterative progress: an approach supplies a specific technique to answer questions within its scope, but at the same time brings various open problems to light that call for input from other approaches; demanding that new insights from one approach consistently integrate with the other approaches leads to greater justification of the black hole models overall. We assert that it is only through such integrative understanding that we advance toward a more accurate, comprehensive, and dynamical image of black holes. 

• Draft available upon request.

New Balances I: Finding Equilibria in Quantum Statistical Mechanics, with Eugene Y.S. Chua [In Preparation]

• Abstract: This paper studies the fate of a foundational concept of classical thermodynamics: thermal equilibrium. First, we argue that it breaks down in integrable and near-integrable regimes of quantum statistical mechanics. Second, we show how one can nonetheless recover something analogous -- and disanalogous -- to thermal equilibrium for such systems, what we call generalized equilibrium. Third, while such a concept will not generally behave in classically thermodynamic ways, we argue that it has four features in common with thermal equilibrium: it is scale-relative, stationary, stable under some perturbations, and supports equilibration. We show how it also supports generalized equilibrium reasoning with four laws analogous to classical thermodynamics. We end by ruminating on whether it matters if such states are ``really" thermodynamic.

Quasi-Local Approaches to Black Holes: From Global Ideals to Local Realities, with Juliusz Doboszewski and Helen Meskhidze [In Preparation]

• Abstract: Philosophers have long worried that certain systems, e.g., black holes or self-gravitating systems, do not `really' behave thermodynamically. These worries typically hold fixed a thick, classical thermodynamic notion of equilibrium and then note its apparent failure in new domains. This paper instead articulates a thin, historically rooted concept of equilibrium that is explicitly scale-relative. On this minimal picture, equilibrium applies whenever (i) some properties appear stationary relative to appropriate spatial and temporal scales; (ii) these stationary properties can be represented as balances between counteracting tendencies; and (iii) we can systematically model how the system responds when the balance is perturbed. We show how this three-part concept underlies familiar uses of equilibrium from classical mechanics to thermodynamics, but also fragments differently in different contexts. We then apply it to two contemporary case studies. In classical and relativistic gravitational thermodynamics, we argue that self-gravitating systems and dynamical black holes admit non-trivial minimal equilibrium regimes, once we attend to scale and to quasi-local horizon structures, even if they lack global thermodynamic equilibria. In quantum statistical mechanics, we argue that prethermal states and generalized Gibbs ensembles support equilibrium reasoning---despite failures of thermalization in the usual Gibbsian sense---because they realize the minimal pattern of balance and response at suitable scales and for restricted classes of observables. Methodologically, we suggest that classical thermodynamics is best viewed as but one historically salient instance of this broader practice of identifying and exploiting minimal equilibrium regimes, rather than as a fixed package to be either fully recovered or abandoned in new domains.

General Philosophy of Science

Fiction and Scientific Representation, (In Chinese), in Journal of Dialectics of Nature 42 (3): 40-48 (2020) [Article]

• Abstract: This article introduces the background from the semantic view of scientific theories and the origin of models to the theory of pragmatic approach.  Callender and Cohen, based on the General Griceanism, think that all forms of representations can be reduced to a general representation, that is, representation as a stipulation. Arguing against it,Toon develops his own theory out of Walton’s pretense theory of representation, that scientific representation is the process to make prescribed imaginations by using scientific models. This article then criticizes Toon’s theory, recognizing the relations among prepared descriptions, equations of motions and imaginative prescriptions, in scientific models, as the metaphor of “barbershop lamp”. It finally introduces the ideas of intervening and imaginative participation in order to solve the epistemological problems in the fictional representation.

History of Science

Through the Looking-Glass: Dodgson and Victorian Mathematics, (In Chinese), in Science and Culture Review 15 (2): 5-16 (2018) [Article]

• Abstract: The development of British mathematics in the Victorian period was as rapid as that of any other field in England. A lasting conflict happened between the new and old ideas in mathematics. In this paper, through analyzing Charles Dodgson's (Lewis Carroll) mathematical work and ideas in his novels, I take him as a mirror to reflect the historical development of mathematics of England in the Victorian period.

PhD Thesis

PhD Thesis: Black Holes Inside and Out: A Philosophical Treatise on Black Hole Physics [Thesis]

• The University of Western Ontario (2025).

• Supervisors: Chris Smeenk and Francesca Vidotto.

• Advosory committee: Carlo Rovelli, Wayne Myrvold, Chris Smeenk, and Francesca Vidotto.

• Examing committee: Karim Thébault (External), Robert DiSalle, Wayne Myrvold, and Martin Houde (Physics).

Selected Talks: Please see on my CV page