Talks: Claus Kiefer and Lorenzo Lorenzetti

The Beyond Spacetime project and the Geneva Symmetry Group are happy to announce a double-header of talks by Claus Kiefer (University of Cologne) and Lorenzo Lorenzetti (University of Bristol), who will be visiting this coming week. The formal talks (abstracts below) will be on

Wednesday, 8 March 2023, in Room L208 (Landolt):

  • 16:15-17:00: Lorenzo Lorenzetti (Bristol): Two forms of functional reductionism in physics
  • 17:00-18:30: Claus Kiefer (Cologne): Origin of irreversibility in the universe

This talk will be a joint session with the other Beyond Spacetime Centre at the University of Illinois at Chicago.

Claus Kiefer will be giving an informal seminar on Thursday in the context of MA seminar on the philosophy of black holes by Saakshi Dulani and Christian Wüthrich:

Thursday, 9 March 2023, at 16:15 in Room PHIL 002 (Philosophes):
Claus Kiefer (Cologne): Observing black holes and insights from quantum gravity

Anyone who wishes to attend is welcome to either of the events.



Lorenzo Lorenzetti (Bristol): Two forms of functional reductionism in physics

Functional reductionism characterises inter-theoretic reduction as the recovery of the upper-level behaviour described by the reduced theory in terms of the lower-level reducing theory. For instance, finding a statistical mechanical realiser that plays the functional role of thermodynamic entropy allows to establish a reductive link between thermodynamics and statistical mechanics.

My aim is to clarify the meaning of functional reductionism in science, with a focus on physics, to flesh out the details of the view and to define both its place with respect to other approaches to reduction and its connection to ontology. I first review the main available framework for functional reduction, originally developed by David Lewis, that I label Syntactic Functional Reductionism. This approach is tied to the syntactic view of theories, is committed to a logical characterisation of functional roles, and it embedded within Nagelian reductionism. Then, I propose a new framework, called Semantic Functional Reductionism. This novel version of functional reduction adopts a semantic view of theories, spells out functional roles mainly in terms of mathematical roles within the models of theories, and is expressed in terms of the related structuralist approach to reduction.

Reading: (draft of the paper)

In terms of technical difficulty, this talk rates 3/5 Einsteins.

Claus Kiefer (Cologne): Origin of irreversibility in the universe

I discuss whether the origin of the observed arrows of time can be derived from quantum cosmology. After a general discussion of the problem, I address the concept of entropy in cosmology and give some numerical estimates. I then present a brief introduction into the formalism of quantum gravity that I use in the following analysis. I investigate the possibility whether a natural boundary condition of low initial entropy can be imposed on the quantum gravitational state. A tentative scenario is discussed in which the observed arrows of time originate from this quantum state.

References: C. Kiefer, AVS Quantum Sci. 4 (2022)1, 015607 or arXiv:2111.02137 [gr-qc];
H. D. Zeh, The Physical Basis of the Direction of Time, 5th ed. (Springer, Berlin, 2007).

In terms of technical difficulty, this talk rates 4/5 Einsteins.


About wuthrich

I am a philosopher of physics at the University of Geneva.
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