# 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.

## Is there evidence for additional neutrino species from cosmology?

Tuesday Nov 12, 2013
Speaker(s):

It has been suggested that recent cosmological and
flavor-oscillation data favor the existence of additional neutrino species
beyond the three standard flavors. We apply Bayesian model selection to
determine whether there is any evidence from current cosmological datasets for
the standard cosmological model to be extended to include additional neutrino
flavors. The datasets employed include cosmic microwave background temperature,
polarization and lensing data, and measurements of the baryon acoustic

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## 13/14 PSI - Condensed Matter - Lecture 2

Tuesday Nov 12, 2013
Speaker(s):
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## 13/14 PSI - Quantum Field Theory II - Lecture 2

Tuesday Nov 12, 2013
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## A universal Hamiltonian simulator: the full characterization

Monday Nov 11, 2013
Speaker(s):

We show that if the ground state energy problem of a
classical spin model is NP-hard, then there exists a choice parameters of the
model such that its low energy spectrum coincides with the spectrum of
\emph{any} other model, and, furthermore, the corresponding eigenstates match
on a subset of its spins. This implies that all spin physics, for example all
possible universality classes, arise in a single model. The latter property was
recently introduced and called Hamiltonian completeness'', and it was shown

Scientific Areas:

## New Constraints on the Amplitude of Cosmic Density Fluctuations and Intracluster Gas from the Thermal SZ Signal Measured by Planck and ACT

Monday Nov 11, 2013

Galaxy clusters form from the rarest peaks in the initial matter distribution, and hence are a sensitive probe of the amplitude of density fluctuations (sigma_8), the amount of matter in the universe, and the growth rate of structure. Galaxy clusters have the potential to constrain dark energy and neutrino masses. However, cluster cosmology is currently limited by systematic uncertainties due to poorly understood intracluster gas physics.

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## 13/14 PSI - Condensed Matter - Lecture 1

Monday Nov 11, 2013
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## 13/14 PSI - Quantum Field Theory II - Lecture 1

Monday Nov 11, 2013
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## Discussion

Friday Nov 08, 2013
Speaker(s):
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## Twist Defects in Topological Systems with Anyonic Symmetries

Friday Nov 08, 2013
Speaker(s):

Twist defects are point-like objects that support robust non-local
storage of quantum information and non-abelian unitary operations.
Unlike quantum deconfined anyonic excitations, they rely on symmetry
rather than a non-abelian topological order. Zero energy Majorana bound
states can arise at lattice defects, such as disclinations and
dislocations, in a topological crystalline superconductor. More general
parafermion bound state can appear as twist defects in a topological

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## Quantum and Classical Anomalies

Friday Nov 08, 2013
Speaker(s):

I will begin reviewing the Callan-Harvey mechanism of anomaly inflow
with particular focus on topological edge states and show how the
inflow  picture naturally converts the non-covariant  "consistent"
gauge anomaly  of Bardeen and Zumino to the more physical "covariant"
anomaly. I will then  discuss some recent  derivations of the covariant
form of the gauge anomaly from classical phase space flows.

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## Lectures On-Demand

Watch on Perimeter's