# 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.

## Quantum Field Theory - Lecture 12B

Wednesday Oct 24, 2012
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## Is spacetime fundamentally discrete?

Wednesday Oct 24, 2012

Modelling continuum dynamics on
discrete space time

We will discuss perfect discretizations which aim at mirroring exactly continuum physics on a given lattice. Such discretizations avoid typical artifacts like Lorentz violation, energy dissipation, particle doubling and in particular breaking of diffeomorphism symmetry. Thus the question arises how to distinguish such lattice dynamics from continuum physics.

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## Quantum Field Theory - Lecture 12A

Wednesday Oct 24, 2012
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## Cosmological Constant

Tuesday Oct 23, 2012

Dark Matter and Dark Energy as a Possible Manifestation of a Fundamental Scale
If we take the idea of the Planck length as a fundamental (minimum) scale and if additionally we impose the Cosmological Constant ($Lambda$) as and infrared (IR) cut-off parameter. Then it is possible to demonstrate that Dark Matter effects can emerge as a consequence of an IR-UV mix effect. This opens the possibility of unifying the Dark Energy and Dark matter effects in a single approach.

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## Quantum Gravity Effects in Black Holes and Gravitational Waves

Tuesday Oct 23, 2012

Quantum-gravity effects as noise for
gravity-wave detectors

I discuss a mechanism that can allow Planck scale effects to manifest themselves as a source of lof-frequency noise for interferometers.  The mechanism requires a discrete formulation of dynamics at the Planck scale.
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Dancing in the Dark: Images of Quantum Black Holes

There have recently been a number of rather surprising suggestions

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## Thermodynamics of correlated quantum systems and a generalized exchange fluctuation theorem.

Tuesday Oct 23, 2012
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I will discuss the central role of correlations in
thermodynamic directionality, how strong correlations can distort the
thermodynamic arrow and contrast these distortions in both the classical and
quantum regimes. These distortions constitute non-linear entanglement witnesses,
and give rise to a rich information-theoretic structure. I shall explain how
these results are then cast into the language of fluctuation theorems to derive
a generalized exchange fluctuation theorem, and discuss the limitations of such
a framework.

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## From Effective Strings to the Simplest theory of Quantum Gravity

Tuesday Oct 23, 2012

String-like objects arise in many quantum field theories.
Well known examples include flux tubes in QCD and cosmic strings. To a first approximation,
their dynamics is governed by the Nambu-Goto action, but for QCD flux tubes
numerical calculations of the energy levels of these objects have become so
accurate that a systematic understanding of corrections to this simple
description is desirable.

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## Searching for Quantum Gravity with the IceCube Neutrino Observatory

Tuesday Oct 23, 2012
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The IceCube Neutrino Observatory is a cubic-kilometer-scale neutrino detector built into the ice sheet at the geographic South Pole.  Completed in December 2010, the detector consists of an array of photomultiplier tubes deployed along 86 cables ("strings") at depths of 1450 to 2450 m, as well as the IceTop air shower array of surface Cherenkov tanks.  IceCube is detecting atmospheric neutrinos of energies above approximately 100 GeV at a rate of ~6 per hour, and is currently searching for extraterrestrial neutrinos from cosmic ray accelerators.  A measurement of the atmospheric neutr

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## An informal discussion about topological gauge theory

Tuesday Oct 23, 2012
Speaker(s):

Reference:

Topological gauge theories and group cohomology

Robbert Dijkgraaf and Edward Witten

http://projecteuclid.org/DPubS?service=UI&version=1.0&verb=Display&handle=euclid.cmp/1104180750

Braiding statistics approach to symmetry-protected topological phases

Michael Levin, Zheng-Cheng Gu

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## New Results in Jet Substructure

Tuesday Oct 23, 2012

We present new results on the performance of jet substructure techniques
and their use in distinguishing the signatures of new boosted massive particles
from the QCD background. Advanced approaches to jet reconstruction using jet
grooming algorithms such as filtering, trimming, and pruning are compared.
Measurements of the jet invariant mass for each jet algorithm are compared both
at the particle level to multiple Monte Carlo event generators and at the
detector level for several configurations of the jet grooming algorithms.

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## Next Public Lecture

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

## LECTURES ON-DEMAND

### Jocelyn Bell Burnell: University of Oxford

Speaker: Jocelyn Bell Burnell