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When scale is surplus

Gryb, Sean and Sloan, David (2021) When scale is surplus. [Preprint]

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Abstract

We study a long-recognised but under-appreciated symmetry called "dynamical similarity" and illustrate its relevance to many important conceptual problems in fundamental physics. Dynamical similarities are general transformations of a system where the unit of Hamilton's principal function is rescaled, and therefore represent a kind of dynamical scaling symmetry with formal properties that differ from many standard symmetries. To study this symmetry, we develop a general framework for symmetries that distinguishes the observable and surplus structures of a theory by using the minimal freely specifiable initial data for the theory that is necessary to achieve empirical adequacy. This framework is then applied to well-studied examples including Galilean invariance and the symmetries of the Kepler problem. We find that our framework gives a precise dynamical criterion for identifying the observables of those systems, and that those observables agree with epistemic expectations. We then apply our framework to dynamical similarity. First we give a general definition of dynamical similarity. Then we show, with the help of some previous results, how the dynamics of our observables leads to singularity resolution and the emergence of an arrow of time in cosmology.


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Item Type: Preprint
Creators:
CreatorsEmailORCID
Gryb, Seans.gryb@hef.ru.nl0000-0002-0439-3548
Sloan, Daviddavidjasloan@gmail.com
Keywords: symmetry, dynamical similarity, surplus structure, cosmology, singularity resolution, arrow of time, contact geometry
Subjects: Specific Sciences > Physics > Cosmology
Specific Sciences > Physics > Relativity Theory
Specific Sciences > Physics > Symmetries/Invariances
Depositing User: Dr Sean Gryb
Date Deposited: 06 Oct 2021 12:23
Last Modified: 06 Oct 2021 12:23
Item ID: 19645
Subjects: Specific Sciences > Physics > Cosmology
Specific Sciences > Physics > Relativity Theory
Specific Sciences > Physics > Symmetries/Invariances
Date: 12 March 2021
URI: http://philsci-archive.pitt.edu/id/eprint/19645

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