Madrid's Polygonal Gravity Seminar Series

The program is:

11:00h Welcome coffee

pie de foto: 

IFT

11:30h First talk

Speaker: José Figueroa-O'Farrill (Edinburgh U.)

Title:  A kinematical Erlanger Programme

Abstract:  Klein’s famous Erlanger Programme was an attempt of describing 
geometries via their symmetries.  The geometries of interest at the time were 
“static”: they did not involve time.  In the 1960s, Bacry and Lévy-Leblond 
pioneered what could be called a “kinematical Erlanger Programme”, essentially 
by introducing time into the geometry.  Their paper “Possible kinematics” 
contained a classification of kinematical Lie algebras for 4-dimensional 
spacetimes, subject to spatial isotropy and parity and time-reversal 
symmetries.  The last two conditions were later dropped in the 1980s by Bacry 
and Nuyts, resulting in classification of spatially isotropic kinematical Lie 
algebras.  In the last decade this classification was extended to arbitrary 
dimension and the corresponding (simply-connected) homogeneous spacetimes were 
classified.  They break up into a small number of classes of geometries, among 
them lorentzian, galilean and carrollian.  The talk will briefly review these 
results and then go on to describing some of what we have learned about such 
geometries (with emphasis on carrollian geometry) and some of their physical 
applications.

pie de foto: 

IFT

15:00h Second talk

Speaker: Harvey Reall (DAMTP, Cambridge U.)

Title: The second law of black hole mechanics in effective field theory

Abstract: The laws of black hole mechanics are an important part of the 
identification of black holes as thermodynamic objects. If this is correct then 
these laws should be robust against the inclusion of higher derivative 
corrections to the Einstein equation. For the first law, this was confirmed by 
the work of Wald et al in the early 1990s, which provides a definition of the 
entropy of a stationary black hole solution of any diffeomorphism invariant 
theory. But it has remained an open problem to generalize this to obtain a 
definition of dynamical black hole entropy that satisfies a second law of black 
hole mechanics. I shall describe a solution to this problem. The key ingredient 
is to treat higher derivative terms according to the rules of effective field 
theory.

16:00h (after the seminar, in any case) Farewell coffee