In this seminar, Miklós Rédei will discuss the role and features of limit objects in the context of physical theories. He will review the concept of ‘limit objects’ as understood in (mathematical) category theory, define the notion of ‘emergent properties’ of limit objects, and give examples. Rédei argues that limit objects in physical theories display a tension between two norms of theory construction in physics. One norm dictates that physical theories should describe all phenomena within a certain domain. The other norm tends to restrict the entities featured in physical theories to those that have a counterpart in the physical world, thereby not allowing imaginary objects that cannot be interpreted realistically. This tension is illustrated by how the infinite *Ising* *model* describes a phase transition, and Rédei will suggest how this tension can be tolerated.

**About the speaker**

Miklós Rédei is Professor of Philosophy in the Department of Philosophy, Logic and Scientfic Method at the London School of Economics. He specialises in the foundational and philosophical problems of modern physics, especially quantum mechanics and quantum field theory, quantum logic, and theories of probablistic causation. In 2013, along with Gábor Hofer-Szabó and László E. Szabó, Miklós published The Principle of the Common Cause. This book gives a technically detailed analysis of the common cause principle: the claim that every correlation is either due to a direct causal effect linking the correlated entities or is brought about by a third factor, a so-called common cause. Another of Miklós’s interests concerns John von Neumann and his work on the foundations of physics. As well as co-editing John von Neumann and the Foundations of Quantum Physics, he has edited a collection of von Neumann’s letters for the American Mathematical Society’s John von Neumann: Selected Letters.

https://www.lse.ac.uk/cpnss/people/miklos-redei

**Practical **

This CLEA-CLPS seminar is taking place at the VUB campus (not online) and is open to everyone interested.

**When. **Friday June 14, 2024 from 12:00 until 14:00h

**Where. **VUB campus Pleinlaan 2, 1050 Elsene. Building C, 5^{th} floor, room C5.03 (vergaderzaal LW or “Proffenzaal”)