Talks: Patricia Palacios

Patricia Palacios (University of Salzburg) will be visiting the Geneva Symmetry Group (GSG) this week. The GSG is happy to present two talks by her, a more formal talk on Wednesday, and an informal seminar on Thursday (abstracts below):

Wednesday, 15 May 2019, at 18:15 in Room L208 (Landolt):

Patricia Palacios (University of Salzburg, with Lapo Casetti): Re-defining equilibrium for long-range interacting systems

Thursday, 16 May 2019, at 16:15 in room B002 (Bastions):

Patricia Palacios (University of Salzburg, with Sean Gryb and Karim Thébault): On the universality of Hawking radiation

Anyone who wishes to attend is welcome.


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Wednesday, 15 May 2019 in Room L208 (Landolt) – Patricia Palacios (University of Salzburg, with Lapo Casetti): Re-defining equilibrium for long-range interacting systems

Abstract: Long-range interacting systems (LRI) are systems in which the interaction potential decays slowly for large inter-particle distance. Typical examples of long-range interactions are the gravitational and Coulomb forces. The philosophical interest for studying these kinds of systems has to do with the fact that they exhibit properties that escape traditional definitions of equilibrium based on stationary probability distributions. How should we define equilibrium for LRI then? In this contribution, we argue that a comparison with ergodicity-breaking phase transitions gives us a qualitative understanding of equilibrium for these kinds of systems in terms of metastable equilibria. As in the case of phase transitions, we contend that in LRI one could account for metastable equilibria by defining the dynamics for finite-time scales. However, in contrast to phase transitions, we show that these metastable states depend on unknown initial conditions and do not correspond to Boltzmannian equilibrium. This negative conclusion provides a possible basis for future scientific research.

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

Thursday, 16 May 2019 in Room B002 (Bastions) – Patricia Palacios (University of Salzburg, with Sean Gryb and Karim Thébault): On the universality of Hawking radiation

Abstract: A physically consistent semi-classical treatment of black holes requires universality arguments to deal with the ‘trans-Planckian’ problem where quantum spacetime effects appear to be amplified such that they undermine the entire semi-classical modelling framework. We evaluate three families of such arguments in comparison with Wilsonian renormalization group universality arguments found in the context of condensed matter physics. Our analysis is framed by the crucial distinction between robustness and universality. Particular emphasis is placed on the quality whereby the various arguments are underpinned by ‘integrated’ notions of robustness and universality. Whereas the principal strength of Wilsonian universality arguments can be understood in terms of the presence of such integration, the principal weakness of all three universality arguments for Hawking radiation is its absence.

Relevant paper: Sean Gryb, Patricia Palacios, and Karim Thébault (2019). On the universality of Hawking radiation. phil-sci archive: http://philsci-archive.pitt.edu/15900/.

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About wuthrich

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