Talk detail

Participant	Haggard, Hal
Institution	Bard College - 30 Campus Road - Annandale-on-Hudson - New York - USA

Session	BH6	Accepted		Order	Time
Talk	Oral abstract	Title	A New Decay Mode for Black Holes
Coauthors
Abstract	I will discuss the recent discovery of a metric satisfying the Einstein equations outside a finite spacetime region where matter collapses into a black hole and then emerges from a white hole. This opens up the possibility that a black hole can quantum-tunnel into a white hole and offers a new decay mode for black holes. For this to happen, quantum gravity should affect the metric also in a small region outside the horizon: contrary to what is commonly assumed, this is not forbidden by causality or by the semiclassical approximation, because quantum effects can pile up over a long time. This scenario alters radically the discussion on the black hole information puzzle.
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Session	GB1	Accepted		Order	Time
Talk	Oral abstract	Title	Fast Radio Bursts from Black to White Hole Explosions
Coauthors
Abstract	Recently a new mode for black hole decay has been proposed by Haggard and Rovelli. In this model a black hole bounces through a tunneling of its geometry and becomes a white hole. In this talk I will describe the proposal of Barrau, Rovelli and Vidotto that primordial black holes evaporating today could give rise to signals with wavelengths not far from those recently observed in fast radio bursts.
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Session	ST3	Accepted		Order	Time
Talk	Oral abstract	Title	SL(2,C) Chern-Simons Theory, a non-Planar Graph Operator, and 4D Quantum Gravity with a Cosmological Constant: Semiclassical Geometry
Coauthors
Abstract	We study the expectation value of a nonplanar Wilson graph operator in SL(2,C) Chern-Simons theory on S3 . In particular we analyze its asymptotic behavior in the double-scaling limit in which both the representation labels and the Chern-Simons coupling are taken to be large, but with fixed ratio. When the Wilson graph operator has a particular form the critical point equations obtained in this double-scaling limit describe a specific class of flat connection on the graph complement manifold. We find that flat connections in this class are in correspondence with the geometries of constant curvature 4-simplices. We also show that the asymptotic behavior of the amplitude contains the Regge action for a single 4-simplex in the presence of a cosmological constant. In particular, the cosmological term contains the full-fledged curved volume of the 4-simplex. Interestingly, the volume term stems from the asymptotics of the Chern-Simons action. This work suggests a new relation between 4-dimensional quantum gravity with a cosmological constant and SL(2,C) Chern-Simons theory in 3-dimensions with knotted graph defects.
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