arXiv subjects

Lorenzo Lorenzetti

Publications and source records attributed to Lorenzo Lorenzetti.

3 recordsLinked to original sources

arXiv2025

Limiting Reduction and Modified Gravity

Modified Newtonian Dynamics (MOND) is a framework of theories that adjust Newton's laws of gravity to explain effects such as galactic rotation anomalies, offering an alternative to dark matter. This essay examines the justification of MOND by assessing its inter-theoretical relationship to established theories across relevant scales, in particular its connection to Newtonian gravitation. We argue that MOND fails a key condition for a theory's justification--what we call 'reduction-wise justification'--since it does not adequately reduce to Newtonian gravity in a fully non-arbitrary way. More precisely, despite satisfying the standard formal criteria for successful limiting reduction, MOND does not properly reduce to Newtonian gravitation because of (i) the absence of a fundamental theoretical framework to justify the interpolating function introduced in MOND and (ii) the lack of a unified mathematical structure working across all scales, independent of Newtonian theory. Hence, the case study of MOND provides crucial results for the general debate on inter-theoretic reduction in science: MOND's failure as a case of reduction highlights important limitations in standard accounts of limiting reduction. We respond by proposing a more refined framework for limiting reduction that introduces two additional criteria to better distinguish successful from pathological reductions. More broadly, this case illustrates how analysing reduction-wise justification can serve as a powerful tool for evaluating the validity of novel theories that are not yet empirically established.

physics.hist-ph↗

arXiv2025

Making Sense of Gravitational Thermodynamics

The use of statistical methods to model gravitational systems is crucial to physics practice, but the extent to which thermodynamics and statistical mechanics genuinely apply to these systems is a contentious issue. This paper provides new conceptual foundations for gravitational thermodynamics by reconsidering the nature of key concepts like equilibrium and advancing a novel way of understanding thermodynamics. The challenges arise from the peculiar characteristics of the gravitational potential, leading to non-extensive energy and entropy, negative heat capacity, and a lack of standard equilibrium. Hence it has been claimed that only non-equilibrium statistical mechanics is warranted in this domain, whereas thermodynamics is inapplicable. We argue instead that equilibrium statistical mechanics applies to self-gravitating systems at the relevant scale, as they display equilibrium in the form of metastable quasi-equilibrium states. We then develop a minimal framework for thermodynamics that can be applied to these systems and beyond. Thermodynamics applies in the sense that we can devise macroscopic descriptions and explanations of the behaviour of these systems in terms of coarse-grained quantities like energy and temperature within equilibrium statistical mechanics.

physics.hist-ph↗

arXiv2022

Functionalising the wavefunction

Functionalism is the view that being x is to play the role of x. This paper defends a functionalist account of three-dimensional entities in the context of Wave Function Realism (WFR), that can explain in detail how we can recover three-dimensional entities out of the wavefunction. In particular, the essay advocates for a novel version of WFR in terms of a functional reductionist approach in the style of David Lewis. This account entails reduction of the upper entities to the bottom ones, when the latter behave appropriately. As applied to WFR, it shows how the wavefunction can turn out to be identical to three-dimensional objects, provided certain conditions. The first major goal of the paper is thus to put forward an improved and more rigorous version of WFR, which dissolves several extant issues about the theory, and can serve as a starting point for the future literature about the topic. Moreover, the second major goal of the article is to take WFR as a case study to demonstrate the pros of functional reductionism, especially in the form defended here, thereby helping to bring this view back in the philosophy of science debate. The positive upshots of this paper suggest a possible application of functional reductionism also to other contexts.

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