BHI Colloquium


Tuesday, February 25, 2020, 1:30pm to 2:30pm


BHI Meeting Room

Gaurav Khanna (UMass Dartmouth)

Title: Observational signatures of near-extremal Kerr black holes

Abstract: In this talk I will present some of my recent work on potential observational signatures of near-extremal and extremal Kerr black holes. The emphasis of this work is on the late-stages of the gravitational wave signal (quasi-normal phase and later) from such black holes, and is of relevance to current and future generation gravitational wave observatories like LIGO/Virgo and LISA. These results are based on very high-accuracy numerical computations in the context of black hole perturbation theory. 


Christopher Smeenk (Western University)

Title: Censorship and the Limits of GR

Abstract: GR allows a variety of solutions with unusual causal structure that pose a threat to determinism. For example, spacetimes such as Taub-NUT admit distinct (non-isometric) extensions beyond a Cauchy horizon. Initial data do not uniquely fix an extension, and in that sense determinism fails. There is a small philosophical literature concerning determinism in GR, following in particular Earman’s seminal contributions. One theme in these discussions regards whether solutions with exotic causal structure should be regarded as “physically reasonable,” or falling within the domain of applicability of GR. Here I will argue that recent results on cosmic censorship suggest that Cauchy horizons fall outside the domain of classical GR, and consider their further implications. 


Anna Ijjas (Max Planck Institute for Gravitational Physics)

Title: Numerical Relativity & Cosmology: An interesting case study
Abstract: I will present recent results where utilizing tools of numerical general relativity led to interesting, previously unnoticed insights in the study of cosmological scenarios.