The Ultra-Relativistic Limit of Black Hole Collisions

Guest speaker: Professor Frans Pretorius, Princeton University

Abstract

Today we have a solid theoretical understanding of the dynamics of black holes, as predicted by classical general relativity, for the typical binary merger expected as an astrophysical gravitational wave source. However, in more "extreme" situations, namely, black holes that collide with velocities close to the speed of light and non-linear perturbations of (near-)extremal black holes, less is known, in some respects even qualitatively. In these lectures I will discuss some of these open questions, describe some recent results, and speculate about possible answers.

The first lecture will focus on ultra-relativistic collisions, where I
will describe recent results from numerical solutions in which we have been
able to push the center-of-mass Lorentz boosts to gamma ~ 5 (98% of the
speed of light). At impact parameters near the threshold of prompt merger,
these results suggest the dynamics of spacetime is better described by the
non-linear dynamics of strongly self-gravitating waves produced by the
collision of curvature "shock fronts," rather than the gravitational-wave-driven
inspiral of two compact objects that better characterizes the astrophysical
regime observed by LIGO.

No need to register in advance for the technical talks, but it is required for the public lecture.

As part of the Lamb Lecture series. Professor Frans Pretorius is also giving a public lecture and a second technical lecture, Professor Pretorius will be giving two technical lectures:

• 19 October: The Ultra-Relativistic Limit of Black Hole Collisions
• 20 October: Approaching Black Hole Extremality