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Realism and Ontology in Quantum Mechanics and String Theory

Richard Dawid, Guilherme Franzmann

TL;DR

The paper argues against tying scientific realism to a single fixed ontology in the presence of dualities, proposing a separation between realism (the truth of the full formal structure) and ontology (observer-based, context-dependent structures that enable empirical access). It reframes ontology as emerging from empirical contexts such as tensor-product decompositions in quantum mechanics and near-classical limits in string theory, drawing on Dennett's compression-algorithm idea to justify realism without fundamentalism. By developing an observer-based ontology and a two-level realism framework, the authors aim to preserve robust structural realism while allowing ontological pluralism across dual representations (e.g., TPS choices, S/T-duality, AdS/CFT). The approach has implications for understanding measurement, locality, and emergence in QM and string theory, and it emphasizes effective theories as anchoring points for ontology within a broader, realist commitment to the full theory. Overall, the work offers a coherent strategy to navigate dualities without sacrificing predictive success or explanatory power.

Abstract

Dualities in physics have challenged traditional forms of scientific realism by undermining the idea that theories describe a unique underlying ontology. In this paper, we develop a new perspective on scientific realism that responds to this challenge. We argue that while realist commitment remains appropriate at the level of a theory's full formal structure, ontological commitment should be treated as tied to specific empirical contexts rather than to a fixed, real ontology. Our proposal draws inspiration from Dennett's notion of a "compression algorithm" as a defining criterion of a scientific theory. On this basis, we separate realism from ontological commitment. To clarify the stakes of this distinction, we contrast our approach with common core realism, which locates ontology in the invariant structure shared by dual models. Focusing on dualities in quantum mechanics and string theory, we show how our view accommodates ontological pluralism while preserving a robust form of structural realism.

Realism and Ontology in Quantum Mechanics and String Theory

TL;DR

The paper argues against tying scientific realism to a single fixed ontology in the presence of dualities, proposing a separation between realism (the truth of the full formal structure) and ontology (observer-based, context-dependent structures that enable empirical access). It reframes ontology as emerging from empirical contexts such as tensor-product decompositions in quantum mechanics and near-classical limits in string theory, drawing on Dennett's compression-algorithm idea to justify realism without fundamentalism. By developing an observer-based ontology and a two-level realism framework, the authors aim to preserve robust structural realism while allowing ontological pluralism across dual representations (e.g., TPS choices, S/T-duality, AdS/CFT). The approach has implications for understanding measurement, locality, and emergence in QM and string theory, and it emphasizes effective theories as anchoring points for ontology within a broader, realist commitment to the full theory. Overall, the work offers a coherent strategy to navigate dualities without sacrificing predictive success or explanatory power.

Abstract

Dualities in physics have challenged traditional forms of scientific realism by undermining the idea that theories describe a unique underlying ontology. In this paper, we develop a new perspective on scientific realism that responds to this challenge. We argue that while realist commitment remains appropriate at the level of a theory's full formal structure, ontological commitment should be treated as tied to specific empirical contexts rather than to a fixed, real ontology. Our proposal draws inspiration from Dennett's notion of a "compression algorithm" as a defining criterion of a scientific theory. On this basis, we separate realism from ontological commitment. To clarify the stakes of this distinction, we contrast our approach with common core realism, which locates ontology in the invariant structure shared by dual models. Focusing on dualities in quantum mechanics and string theory, we show how our view accommodates ontological pluralism while preserving a robust form of structural realism.

Paper Structure

This paper contains 35 sections, 28 equations, 1 figure, 2 tables.

Table of Contents

  1. Introduction
  2. Dualities
  3. Dualities in Quantum Mechanics
  4. Composition of Quantum Systems
  5. Breaking Down Quantum Systems
  6. Dualities in String Theory
  7. S- and T-duality
  8. T-duality.
  9. S-duality.
  10. AdS/CFT correspondence
  11. The specific character of string dualities
  12. Common Core Realism and Related Views
  13. De Haro and Butterfield on theories and models
  14. The common core
  15. The Common Core in Quantum Mechanics
  16. ...and 20 more sections

Figures (1)

  • Figure 1: Dualities between the five types of Superstring theories (type IIA, type IIB, heterotic $E_{8}\times E_{8}$, heterotic $SO(32)$, and type I) and M-theory. The extended 11th dimension of M-theory corresponds to the strength of the string coupling of type IIA and heterotic $E_{8}\times E_{8}$ in the dual pictures. Type IIB is S-self-dual.

Theorems & Definitions (4)

  • Definition 2.1: TPS
  • Definition 2.2: Duality
  • Definition 2.3: k-Duality
  • Definition 3.1: Duality