# Video Library

Since 2002 Perimeter Institute has been recording seminars, conference talks, and public outreach events using video cameras installed in our lecture theatres.  Perimeter now has 7 formal presentation spaces for its many scientific conferences, seminars, workshops and educational outreach activities, all with advanced audio-visual technical capabilities.  Recordings of events in these areas are all available On-Demand from this Video Library and on Perimeter Institute Recorded Seminar Archive (PIRSA)PIRSA is a permanent, free, searchable, and citable archive of recorded seminars from relevant bodies in physics. This resource has been partially modelled after Cornell University's arXiv.org.

## Could LIGO's black holes be primordial and what is an easy way to figure that out?

Wednesday Nov 08, 2017
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## Measuring the polarization content of gravitational waves with LIGO

Wednesday Nov 08, 2017

I will give a brief overview of LIGO’s efforts to test general relativity with gravitational waves. My main focus will be on tests of alternative polarizations.

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## Testing pseudo-complex general relativity with gravitational waves

Wednesday Nov 08, 2017
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We show how the model of pseudo-complex general relativity can be tested using gravitational wave signals from coalescing compact objects. The Model, which agrees with Einstein gravity in the weak-field limit, diverges dramatically in the near-horizon regime, with certain parameter ranges excluding the existence of black holes. We show that simple limits can be placed on the model in both the inspiral and ringdown phase of coalescing compact objects.
We discuss further how these limits relate to current observational bounds.

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## A Recipe for Echoes

Wednesday Nov 08, 2017
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## Inspiral Tests of Strong-field Gravity and Ringdown Tests of Quantum Black Holes

Wednesday Nov 08, 2017
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The binary black hole merger events recently discovered by the LIGO and Virgo Collaboration offer us excellent testbeds for exploring extreme (strong and dynamical-field) gravity that was previously inaccessible. In this talk, I will first explain the current status of probing fundamental pillars of General Relativity using the inspiral part of the gravitational waveform. I will next describe how well one can constrain one type of quantum black holes, collapsed polymers, with the GW150914 ringdown. I will conclude with a list of important open problems.

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## Operational General Relativity - Lecture 4

Wednesday Nov 08, 2017
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## Discussion: Evidence for Echoes

Wednesday Nov 08, 2017

## An alternative significance estimation for the evidence for echoes

Wednesday Nov 08, 2017
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The noise dominated nature of the gravitational wave detectors requires an assessment of the noise background in the search for astrophysical signals. Starting with a frequentist approach, the original analysis used about 16 seconds of data after the merger signal to find how frequently random noise mimics the expected signal. We present the results of extending the background estimation to 4096 seconds of public LIGO data and discuss the concerns arising from subtleties in the analysis for the long and self-similar echo templates.

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## PSI 17/18 - Condensed Matter - Lecture 3

Wednesday Nov 08, 2017
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## A model-independent search for gravitational-wave echoes

Wednesday Nov 08, 2017
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Exotic compact objects (e.g. boson stars, dark matter stars, gravastars), and certain quantum modifications to black holes (e.g. firewalls) are speculated to give out echoes'' or bursts of radiation appearing at regular time intervals due to a perturbation by any infalling matter or field. In particular, these echoes are also expected to appear soon after their formation.

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