# 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.

## Virasoro Symmetry of 4D Quantum Gravity

Wednesday May 17, 2017
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## Through the Big Bang

Wednesday May 17, 2017
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I will show how the intrinsic definition of observables in relativity through dynamical similiarity (known as Shape Dynamics) leads to the continuation of Einstein's equations classically through the big bang singularity in simple cosmological scenarios. By appealing to general principles I argue that this is a generic feature, and that the singularity can be viewed as an artifact of the redundant description imposed by absolute length scales.

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## Shape dynamics in terms of connection variables

Tuesday May 16, 2017
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## Weyl invariance and quantum gravity

Tuesday May 16, 2017
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I will discuss various ways of realizing the Weyl group in a theory of gravity, and the presence or absence of anomalies.

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## Emergence of Supergroups from Junctions of M-branes

Tuesday May 16, 2017
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We study the boundary conditions in the topologically twisted Chern-Simons matter theories with the Lie 3-algebraic structure. We find that the supersymmetric boundary conditions and the gauge invariant boundary conditions can be unified as the complexified gauge invariant boundary conditions which lead to the supergroup WZW models.

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## Renormalization Group flows of spacetime

Tuesday May 16, 2017
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I will discuss the use of (functional) Renormalization Group in models of quantum gravity. I will highlight the challenges that occur in continuum approaches to quantum gravity, such as asymptotically safe gravity, as well as challenges in discrete approaches, such as tensor models.

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## Implications of a Frame-Dependent Dark Energy Action

Tuesday May 16, 2017
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I review motivations for a frame-dependent dark energy action proportional to $\int d^4x (-g)^{1/2}/g_{00}^2$, and discuss implications for the black hole horizon and for perturbations on the Robertson-Walker line element.

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## Studying Fast Radio Bursts with the HIRAX Telescope

Tuesday May 16, 2017
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Fast Radio Bursts are mysterious radio flashes that appear to have extragalactic origin. The inferred isotropic brightness temperature for these events can exceed 10^34 K. Discovered in 2006, only about 25 have been reported to date.

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## What we know and don’t know about solutions to the Einstein Constraint Equations

Tuesday May 16, 2017
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## A Weyl-Type Theorem in Geometrized Newtonian Gravity, and How It May Bear on Shape Dynamics

Monday May 15, 2017
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The Weyl Theorem states that the conformal structure and the projective structure jointly suffice to fix the metric up to a global constant. This is a powerful interpretive tool in general relativity: it says in effect that if I know the paths of light rays in vacuo and I know the images of the paths of freely falling particles (i.e., the spacetime curves they follow with no preferred parametrization), then I know the metric.

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## Next Public Lecture

Check back for details on the next lecture in Perimeter's Public Lectures Series

## RECENT PUBLIC LECTURE

### Janna Levin: Black Hole Blues and Other Songs from Outer Space

Speaker: Janna Levin