Researcher:
Chen, Lu

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Lu

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Chen

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Chen, Lu

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2021 - 20223

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Researcher Of Publications: search.filters.isAuthorOfPublication.5d09000b-b657-4237-b9f8-d7efca33f868

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    Can we "effectivize" spacetime?
    (Elsevier Sci Ltd, 2022) Department of Philosophy; Chen, Lu; Faculty Member; Department of Philosophy; College of Social Sciences and Humanities; 329122
    According to effective realism, scientific theories give us knowledge about the unobservable world, but not at the fundamental level. This view is supported by the well-received effective -field-theory (EFT) approach to high energy physics, according to which even our most successful physical theories are only applicable up to a certain energy scale and expected to break down beyond that. In this paper, I advance new challenges for effective realism and the EFT approach. I argue that effective quantum gravity (EQG) does not give us a realistic theory of spacetime even within its scope of validity. This also exposes a general interpretative dilemma faced by all EFTs concerning their indispensable references to classical spacetime beyond their scope of validity.
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    Smooth infinitesimals in the metaphysical foundation of spacetime theories
    (Springer Nature, 2022) Department of Philosophy; Chen, Lu; Faculty Member; Department of Philosophy; College of Social Sciences and Humanities; 329122
    I propose a theory of space with infinitesimal regions called smooth infinitesimal geometry (SIG) based on certain algebraic objects (i.e., rings), which regiments a mode of reasoning heuristically used by geometricists and physicists (e.g., circle is composed of infinitely many straight lines). I argue that SIG has the following utilities. (1) It provides a simple metaphysics of vector fields and tangent space that are otherwise perplexing. A tangent space can be considered an infinitesimal region of space. (2) It generalizes a standard implementation of spacetime algebraicism (according to which physical fields exist fundamentally without an underlying manifold) called Einstein algebras. (3) It solves the long-standing problem of interpreting smooth infinitesimal analysis (SIA) realistically, an alternative foundation of spacetime theories to real analysis (Lawvere Cahiers de Topologie et Geometrie Differentielle Categoriques, 21(4), 277-392, 1980). SIA is formulated in intuitionistic logic and is thought to have no classical reformulations (Hellman Journal of Philosophical Logic, 35, 621-651, 2006). Against this, I argue that SIG is (part of) such a reformulation. But SIG has an unorthodox mereology, in which the principle of supplementation fails.
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    PublicationOpen Access
    An algebraic approach to physical fields
    (Elsevier, 2021) Fritz, Tobias; Department of Philosophy; Chen, Lu; Faculty Member; Department of Philosophy; College of Social Sciences and Humanities
    According to the algebraic approach to spacetime, a thoroughgoing dynamicism, physical fields exist without an underlying manifold. This view is usually implemented by postulating an algebraic structure (e.g., commutative ring) of scalar-valued functions, which can be interpreted as representing a scalar field, and deriving other structures from it. In this work, we point out that this leads to the unjustified primacy of an undetermined scalar field. Instead, we propose to consider algebraic structures in which all (and only) physical fields are primitive. We explain how the theory of natural operations in differential geometry-the modern formalism behind classifying diffeomorphism-invariant constructions-can be used to obtain concrete implementations of this idea for any given collection of fields. For concrete examples, we illustrate how our approach applies to a number of particular physical fields, including electrodynamics coupled to a Weyl spinor.