Interpreting theories without a spacetime

2018

Self Cite

I conceptualise the role of dualities in quantum gravity, in terms of their functions for theory construction. I distinguish between two functions of duality in physical practice: namely, discovering and describing 'equivalent physics', versus suggesting 'new physics'. I dub these the 'theoretical' versus the 'heuristic' functions of dualities. The distinction seems to have gone largely unnoticed in the philosophical literature: and it exists both for dualities, and for the more general relation of theoretical equivalence. The paper develops the heuristic function of dualities: illustrating how they can be used, if one has any luck, to find and formulate new theories. I also point to the different physical commitments about the theories in question that underlie these two functions. I show how a recently developed schema for dualities articulates the differences between the two functions.

Section: Tools For Theory Constructionmentioning

confidence: 74%

The heuristic function of duality

2018

Self Cite

“…But this is of course not how interpretations come about in physics (as I also emphasised in the example of Maxwell's theory): they are always constructed against the background of already existing theories. This methodological point is expounded in De Haro and De Regt (2018), which gives three interpretative tools that can be used to construct internal interpretations, i.e. without interpreting the specific structure (see also Dewar (2017: §6) for some excellent comments on related issues).…”

Section: Discussionmentioning

confidence: 99%

Theoretical equivalence and duality

2019

Self Cite

Theoretical equivalence and duality are two closely related notions: but their interconnection has so far not been well understood. In this paper I explicate the contribution of a recent schema for duality to discussions of theoretical equivalence. I argue that duality suggests a construal of theoretical equivalence in the physical sciences. The construal is in terms of the isomorphism of models, as defined by the Schema. This construal entails interpretative constraints that should be useful for theoretical equivalence more generally. I illustrate the construal in various formulations of Maxwell's electromagnetic theory. 2 The Schema as a Proposal for Theoretical Equivalence I first present, in Section 2.1, the Schema for theories and duality: from De Haro (2016: §1.1- §1.2) and De Haro and Butterfield (2017: §2.2- §2.3). Section 2.2 contains the proposal for theoretical equivalence, based on this Schema. Section 2.3 contrasts the notions of theoretical equivalence and physical equivalence. 5

“…In the previous subsection, we gave several examples of theories which have no spacetime at the basic level, but in which some kind of spacetime is recovered in a suitable limit, thus contributing to understanding through the use of geometric reasoning and intuition, according to the tools (Approximation) and (Similar) in §4.1. (Again, the examples here are further developed in De Haro and De Regt (2018)).…”

Section: Physics In the Abyss: No Spacetime And No Visualizationmentioning

confidence: 99%

“…We will reframe the debates in terms of different views on (BQ). Section 4 takes up question (iv) by analysing explicit examples in the physics literature, and proposes a set of tools which are available for understanding in quantum gravity (these examples and tools are dealt with more fully in a companion paper, De Haro and De Regt (2018)).…”

Section: Introductionmentioning

confidence: 99%

A precipice below which lies absurdity? Theories without a spacetime and scientific understanding

Regt

2018

Self Cite

While the relation between visualization and scientific understanding has been a topic of longstanding discussion, recent developments in physics have pushed the boundaries of this debate to new and still unexplored realms. For it is claimed that, in certain theories of quantum gravity, spacetime 'disappears': and this suggests that one may have sensible physical theories in which spacetime is completely absent. This makes the philosophical question whether such theories are intelligible, even more pressing. And if such theories are intelligible, the question then is how they manage to do so. In this paper, we adapt the contextual theory of scientific understanding, developed by one of us, to fit the novel challenges posed by physical theories without spacetime. We construe understanding as a matter of skill rather than just knowledge. The appeal is thus to understanding, rather than explanation, because we will be concerned with the tools that scientists have at their disposal for understanding these theories. Our central thesis is that such physical theories can provide scientific understanding, and that such understanding does not require spacetimes of any sort. Our argument consists of four consecutive steps: (a) We argue, from the general theory of scientific understanding, that although visualization is an oft-used tool for understanding, it is not a necessary condition for it; (b) we criticise certain metaphysical preconceptions which can stand in the way of recognising how intelligibility without spacetime can be had; (c) we catalogue tools for rendering theories without a spacetime intelligible; and (d) we give examples of cases in which understanding is attained without a spacetime, and explain what kind of understanding these examples provide.Keywords: scientific understanding, intelligibility of theories, quantum gravity, emergence of spacetime 1 Forthcoming in Synthese.