Events

Limiting Reduction and Modified Gravity

Abstract: The validity of a scientific theory depends crucially on its relationships with other established theories. A necessary condition for justifying a physical theory is its ability to recover established effective theories at their respective scales, provided it applies to those domains. More precisely, it should be reducible to narrower theories in the appropriate limit. We examine limiting reduction in the context of Modified Newtonian Dynamics (MOND) and assess the extent to which various classical and relativistic versions of the theory successfully recover Newtonian gravity at the appropriate scales. Our analysis shows that although the reduction of MOND to Newtonian gravity meets the standard conditions for limiting reduction in the literature, it ultimately proves to be an unsuccessful case of reduction. This failure stems from (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 across all scales, independent of Newtonian theory. Hence, MOND is not (yet) justified as a theory in a crucial sense. As a consequence, our analysis also reveals that existing accounts of limiting reduction are insufficiently fine-grained to distinguish valid from pathological cases of reduction. This case study then serves as an ideal foundation for improving the limiting approach to inter-theoretic reduction. We refine the standard framework by introducing two additional criteria for successful reduction.

Zoom Link

Meeting ID: 930 4120 7032 Password: HarvardBHI

Monday, April 14, 2025 9:30 AM