Talks

I will review the analysis of boundary symmetries in first order 3d gravity, and explain how the study of the boundary current algebra and the Sugawara construction actually leads to two dual notions of diffeomorphism charges. This provides a new understanding of the relationship between the second order and first order formulations, and of the existence of finite distance asymptotic symmetries (as strange as this sounds) in topological theories. This analysis is performed on the most general theory of first order 3d gravity, which also enables to understand the duality between curvature and torsion, as well as the relationship with chiral and massive gravity.

We construct, for the first time, the time-domain gravitational-wave strain waveform from the collapse of a strongly gravitating Abelian Higgs cosmic string loop in full general relativity. We show that the strain exhibits a large memory effect during merger, ending with a burst and characteristic ringdown as a black hole is formed. Furthermore, we investigate the waveform and energy emitted as a function of width, radius and string tension Gμ. We find that the mass normalized gravitational-wave energy displays a strong dependence on the inverse of the string tension E_GW / M_0 ∝ 1/Gμ, with E_GW / M_0 ∼ O(1)% at the percent level, for the regime where Gμ ~ 1e-3 . Conversely, we show that the efficiency is only weakly dependent on the initial string width and initial string radii. Using these results, we argue that gravitational wave production is dominated by kinematical instead of geometrical considerations.

Many of previous approaches for the firewall puzzle rely on a hypothesis that interior partner modes are embedded on the early radiation of a maximally entangled black hole. Quantum information theory, however, casts doubt on this folklore and suggests a different tale; the outgoing Hawking mode will be decoupled from the early radiation once an infalling observer, with finite positive energy, jumps into a black hole. In this talk, I will provide counterarguments against current mainstream proposals and present an alternative resolution of the firewall puzzle which is consistent with predictions from quantum information theory. My proposal builds on the fact that interior operators can be constructed in a state-independent manner once an infalling observer is explicitly included as a part of the quantum system. Hence, my approach resolves a version of the firewall puzzle for typical black hole microstates as well on an equal footing.