# 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.

## Long-lived interacting phases of matter protected by multiple time-translation symmetries in quasiperiodically driven systems

Tuesday Oct 08, 2019
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The discrete time-translation symmetry of a periodically-driven (Floquet) system allows for the existence of novel, nonequilibrium interacting phases of matter. A well-known example is the discrete time crystal, a phase characterized by the spontaneous breaking of this time-translation symmetry.

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## Stringy ER=EPR

Tuesday Oct 08, 2019
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I will describe an example in which ER=EPR can be understood as a worldsheet string duality, by finding the Lorentzian continuation of the FZZ duality. The result is that string perturbation theory around the thermofield double state in a disconnected spacetime with a condensate of entangled folded strings is equivalent to string theory in a connected two sided black hole spacetime. Important ingredients are the Lorentzian interpretation of time winding vertex operators, and string theory with target space Schwinger-Keldysh contours.

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## Python and Numpy

Tuesday Oct 08, 2019
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The core Python language is not particularly powerful or fast for numerical computing.  Fortunately, there is a large "numerical python" library, "numpy", that is a standard part of any Python-using scientist's toolkit.  I will present numpy, the associated "scientific python" library, "scipy", and the popular "matplotlib" plotting library.

## PSI 2019/2020 - Statistical Mechanics (Vieira) - Lecture 3

Tuesday Oct 08, 2019
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## PSI 2019/2020 - Quantum Field Theory (Wohns/Xu) - Lecture 2

Tuesday Oct 08, 2019
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## PSI 2019/2020 - Statistical Mechanics (Vieira) - Lecture 2

Monday Oct 07, 2019
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## PSI 2019/2020 - Quantum Field Theory (Wohns/Xu) - Lecture 1

Monday Oct 07, 2019
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## General Relativity for Cosmology - Lecture 9

Friday Oct 04, 2019
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## Cohomology of hyperkahler manifolds

Thursday Oct 03, 2019
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I will talk about compact hyperkahler manifolds, which generalize the famous K3 surface to the higher dimensions. Given a compact simple hyperkahler manifold $M$, I will describe how the structure of cohomology algebra H*(M) is related with the so(b_2+2) Lie algebra action and the second cohomology group. I will explain how this is applied to the generalization of Kuga-Satake construction which allows us to assign for K3-type Hodge structure a Hodge structure of weight one (i.e. complex torus).

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## Challenges in gravitational wave astronomy

Thursday Oct 03, 2019
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Advanced LIGO and Advanced Virgo are currently in the middle of their third observing run, and releasing open public event alerts for the first time. The LIGO-Virgo collaboration has issued 29 un-retracted candidate event alerts as of September 20th, 2019, potentially adding dozens more known compact binary object mergers to the eleven confident LIGO-Virgo detections from the first two Advanced-era observing runs. I’ll review novel LIGO-Virgo results to date, and discuss the challenges of extracting interesting new physics from noisy detector data.

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## Lectures On-Demand

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