Search Talks

Readings:
The basics of gravitational wave theory, by Flanagan & Hughes, https://iopscience.iop.org/article/10.1088/1367-2630/7/1/204
Gravitational-Wave Tests of General Relativity with Ground-Based Detectors and Pulsar-Timing Arrays, by Yunes et al. https://arxiv.org/pdf/2408.05240
Tests of General Relativity with GW150914, LIGO Collaboration, https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.221101
Tests of general relativity with the binary black hole signals from the LIGO-Virgo catalog GWTC-1, LIGO Collaboration, https://journals.aps.org/prd/abstract/10.1103/PhysRevD.100.104036
Probing the black hole metric: Black hole shadows and binary black-hole inspirals, by Psaltis et al., https://journals.aps.org/prd/abstract/10.1103/PhysRevD.103.104036
New horizons for fundamental physics with LISA, https://link.springer.com/article/10.1007/s41114-022-00036-9

For the first time in history, we have captured images of black holes, allowing us to study their event horizons—the very boundaries beyond which nothing escapes. This achievement, realized through the Event Horizon Telescope (EHT), was the result of two decades of innovation, collaboration, and technological advancements. By linking radio telescopes across the globe, we created an Earth-sized observatory capable of resolving the shadows cast by supermassive black holes. These images have confirmed Einstein’s predictions, tested gravity in extreme conditions, and provided unprecedented insights into black hole physics. But this is just the beginning. Future advancements in imaging techniques, additional telescopes, and space-based interferometry will sharpen our view and allow us to explore black holes across the universe. As we push the boundaries of observation, we will uncover even more mysteries about these enigmatic cosmic giants and their role in shaping galaxies.

Readings:
Testing general relativity with the Event Horizon Telescope, by Psaltis, D., https://link.springer.com/article/10.1007/s10714-019-2611-5
Gravitational Test beyond the First Post-Newtonian Order with the Shadow of the M87 Black Hole, by D. Psaltis and the EHT Collaboration, https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.125.141104
First Sagittarius A* Event Horizon Telescope Results. VI. Testing the Black Hole Metric, EHT Collaboration, https://iopscience.iop.org/article/10.3847/2041-8213/ac6756/pdf

Readings:
Kerr Black Holes Are Not Unique to General Relativity, by D. Psaltis https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.100.091101
Gravitational waves from the inspiral of a compact object into a massive, axisymmetric body with arbitrary multipole moments by F. Ryan  https://journals.aps.org/prd/abstract/10.1103/PhysRevD.52.5707
Towards a formalism for mapping the spacetimes of massive compact objects: Bumpy black holes and their orbits, by Collins & Hughes, https://journals.aps.org/prd/abstract/10.1103/PhysRevD.69.124022
Systematic study of event horizons and pathologies of parametrically deformed Kerr spacetimes, by T. Johannsen, https://journals.aps.org/prd/abstract/10.1103/PhysRevD.87.124017
Metric for rapidly spinning black holes suitable for strong-field tests of the no-hair theorem, by Johannsen & Psaltis, https://journals.aps.org/prd/abstract/10.1103/PhysRevD.83.124015
Spacetime and orbits of bumpy black holes, by Vigeland & Hughes, https://journals.aps.org/prd/abstract/10.1103/PhysRevD.81.024030
Regular black hole metric with three constants of motion, by T. Johannsen, https://journals.aps.org/prd/abstract/10.1103/PhysRevD.88.044002

Readings:
Black Holes in Classical General Relativity and Beyond, by D. Psaltis https://www.worldscientific.com/doi/10.1142/9789811282676_0001
The Kerr spacetime: A brief introduction, by M. Visser https://arxiv.org/pdf/0706.0622

The talk will discuss a different modification to the Bala-Goyal framework.  Here agents form beliefs based on their own experience and that of their neighbors, just like in the base model.  But they do not always perform the action they believe is best.  Instead, they weigh their expected payoff from taking a given action against their preference for conforming with their neighbors.  This modification leads to several new effects, including a different way in which polarization may arise, this time due to network structure.  We will conclude by reflecting on what it means that there are multiple, apparently distinct ways in which polarization can arise in simple models.