Video Library

Since 2002 Perimeter Institute has been recording seminars, conference talks, public outreach events such as talks from top scientists 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 and 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.

Accessibly by anyone with internet, Perimeter aims to share the power and wonder of science with this free library.

A new look at symmetries of 3d gravity

Thursday Jan 21, 2021
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I will review the analysis of boundary symmetries in first order 3d gravity, and explain how the study of the boundary current algebra and the Sugawara construction actually leads to two dual notions of diffeomorphism charges. This provides a new understanding of the relationship between the second order and first order formulations, and of the existence of finite distance asymptotic symmetries (as strange as this sounds) in topological theories.

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Coherent Gravitational Waveforms and Memory from Cosmic String Loops

Thursday Jan 21, 2021

We construct, for the first time, the time-domain gravitational-wave strain waveform from the collapse of a strongly gravitating Abelian Higgs cosmic string loop in full general relativity. We show that the strain exhibits a large memory effect during merger, ending with a burst and characteristic ringdown as a black hole is formed. Furthermore, we investigate the waveform and energy emitted as a function of width, radius and string tension Gμ.

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On the firewall puzzle

Wednesday Jan 20, 2021
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Many of previous approaches for the firewall puzzle rely on a hypothesis that interior partner modes are embedded on the early radiation of a maximally entangled black hole. Quantum information theory, however, casts doubt on this folklore and suggests a different tale; the outgoing Hawking mode will be decoupled from the early radiation once an infalling observer, with finite positive energy, jumps into a black hole.

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Probing angular-dependent primordial non-Gaussianity from galaxy intrinsic alignments

Tuesday Jan 19, 2021
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The primordial non-Gaussianity (PNG) is a key feature to screen various inflationary models and it is one of the main targets in the next generation galaxy surveys. In particular, the local-type of PNG makes the galaxy bias scale-dependent in large-scales, which is known as the scale-dependent bias, allowing to constrain the local-type PNG from galaxy surveys. In this talk, I will present the galaxy shape correlation, called the intrinsic alignment'', can explore the angular-dependent PNG.

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Peierls bracket and gravitational dressing in Jackiw-Teitelboim gravity

Tuesday Jan 19, 2021
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How to deal with diffeomorphism symmetries is one of the difficult problems in general relativity. Because of the diffeomorphism symmetries, we need to consider diffeomorphism invariant operators and gravitational dressing. In this work, we consider a special gravitational dressing which is to locate the operator by shooting geodesic from the spatial boundary. We try to use Peierls bracket to study the commutator between this gravitational dressing operator and the ADM energy operator.

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Emergent fractons in Elusive Bose Metal --- When IR theory blends with UV physics

Monday Jan 18, 2021
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The entanglement pattern of a quantum many-body system can be characterized by quasiparticles and emergent gauge fields, much like those found in Maxwell's theory. My talk begins with the basic aspects of symmetry fractionalization and emergent gauge fields in strongly correlated systems. I will further extend this paradigm into a new type of quantum many-body state, dubbed "fracton phase," from a quantum melting transition of plaquette paramagnetic crystals.

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Physical implications of a fundamental period of time

Thursday Jan 14, 2021
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If time is described by a fundamental process rather than a coordinate, it

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The parents of LIGO black holes and their hometown

Thursday Jan 14, 2021
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Two of the dominant channels to produce black-hole binary mergers are believed to be the isolated evolution of stellar binaries in the field and dynamical formation in star clusters. Pair instabilities prevent stellar collapse from generating black holes more massive than about 45-60 solar mass. This  “mass gap” only applies to the field formation scenario: repeated mergers in clusters can fill the gap. A similar reasoning applies to the binary’s spin parameters.

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Entangled subspaces and generic local state discrimination with pre-shared entanglement

Wednesday Jan 13, 2021
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Walgate and Scott have determined the maximum number of generic pure quantum states in multipartite space that can be unambiguously discriminated by an LOCC measurement [Journal of Physics A: Mathematical and Theoretical, 41:375305, 08 2008]. In this work, we determine this number in a more general setting in which the local parties have access to pre-shared entanglement in the form of a resource state. We find that, for an arbitrary pure resource state, this number is equal to the Krull dimension of (the closure of) the set of pure states obtainable from the resource state by SLOCC.

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Conformal embedding of random planar maps

Wednesday Jan 13, 2021
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A planar map is a canonical model for a discrete surface which is studied in probability theory, combinatorics, theoretical physics, and geometry. Liouville quantum gravity provides a natural model for a continuum random surface with roots in string theory and conformal field theory. After introducing these objects, I will present a joint work with Xin Sun where we prove convergence of random planar maps to a Liouville quantum gravity surface under a discrete conformal embedding which we call the Cardy embedding.

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