167 | Chiara Marletto on Constructor Theory, Physics, and Possibility
Oct 4, 2021
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Chiara Marletto, a research fellow at the University of Oxford, delves into constructor theory, offering a fresh perspective on physics that prioritizes possibilities over traditional laws. She discusses its implications for understanding quantum gravity and thermodynamics. The conversation also covers the vital role of conservation laws, the complexities of irreversibility, and how information theory intersects with physics. Marletto's insights challenge conventional thinking, emphasizing how reframing our understanding could unlock new scientific pathways.
Constructor theory emphasizes counterfactuals over dynamical laws for a new perspective on physics.
Incorporating counterfactuals expands explanations of what is possible and impossible in the universe.
Constructor theory offers a unified framework treating microscopic and emergent phenomena equally.
Deep dives
Constructor Theory and the Concept of Fundamental Laws of Physics
Constructor theory introduces a new perspective on fundamental laws of physics by emphasizing the role of counterfactuals. Instead of solely focusing on specific dynamical laws and initial conditions, constructor theory considers a broader set of statements about what is possible and impossible in the universe. By including these counterfactual principles, constructor theory aims to provide a more comprehensive and systematic explanation of physical phenomena.
Counterfactuals and Their Application in Constructor Theory
In constructor theory, counterfactuals play a crucial role in explaining physical phenomena beyond traditional views of fundamental physics. These counterfactual statements address what could be transformed or constructed, shedding light on the constraints and possibilities within the universe. By incorporating counterfactuals, constructor theory seeks to extend the scope of explanations beyond conventional dynamical laws and initial conditions.
Constructor Theory's Relationship Between Microscopic and Emergent Levels of Physics
Constructor theory challenges the distinction between microscopic and emergent levels of physics by offering a unified framework that applies across scales. It treats both microscopic and emergent phenomena with equal importance, focusing on general principles that govern transformations and constructions. This approach aims to provide insights that transcend traditional views of physics, encompassing a wide range of objects and systems at different scales.
Pragmatic Approach in Constructor Theory
In adopting a pragmatic approach, constructor theory emphasizes the value of counterfactuals and general principles in explaining physical phenomena. While acknowledging the contributions of philosophical and metaphysical discussions on counterfactuals, constructor theory focuses on practical applications to enhance our understanding of fundamental laws of physics. By considering a wide range of scenarios and constraints through counterfactual reasoning, constructor theory aims to offer a comprehensive and insightful perspective on the nature of the universe.
The Concept of Irreversibility and the Arrow of Time
The podcast delves into the concept of irreversibility in the context of the arrow of time and microscopic processes. While traditional physics indicates that all processes are reversible at the microscopic level, the addition of past low entropy conditions leads to irreversibility. The discussion includes examples like the carnot cycle to illustrate certain impossibilities at the microscopic scale, challenging the conventional understanding of irreversibility and highlighting the need to reevaluate the distinctions between approximate and exact statements.
The Link Between Information Theory, Thermodynamics, and Work Extraction
The podcast explores the connection between information theory, thermodynamics, and work extraction, focusing on principles like constructing theory and distinguishability of states. By considering the irreducible thermodynamic cost of tasks like erasing information, the discussion delves into theories of constructors and their applications in biological systems. It suggests a shift in perspectives to uncover common solutions to diverse scientific problems, emphasizing the potential of novel insights when approaching complex issues from different angles.
Traditional physics works within the “Laplacian paradigm”: you give me the state of the universe (or some closed system), some equations of motion, then I use those equations to evolve the system through time. Constructor theory proposes an alternative paradigm: to think of physical systems in terms of counterfactuals — the set of rules governing what can and cannot happen. Originally proposed by David Deutsch, constructor theory has been developed by today’s guest, Chiara Marletto, and others. It might shed new light on quantum gravity and fundamental physics, as well as having applications to higher-level processes of thermodynamics and biology.
