# 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.

## The Effectiveness of Group Theory in Quantum Mechanics

Thursday Mar 12, 2009
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Eugene Wigner and Hermann Weyl led the way in applying the theory of group representations to the newly formulated theory of quantum mechanics starting in 1927. My talk will focus, first, on two aspects of this early work. Physicists had long exploited symmetries as a way of simplifying problems within classical physics.

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## Quantum graphity: a model of emergent locality in quantum gravity

Wednesday Mar 11, 2009
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Quantum graphity is a background independent condensed matter model for emergent locality, spatial geometry and matter in quantum gravity. The states of the system are given by bosonic degrees of freedom on a dynamical graph on N vertices. At high energy, the graph is the complete graph on N vertices and the physics is invariant under the full symmetric group acting on the vertices and highly non-local. The ground state dynamically breaks the permutation symmetry to translations and rotations. In this phase the system is ordered, low-dimensional and local.

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## Mini-Course on Mach's Principle - Lecture 5

Wednesday Mar 11, 2009
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## What is the objective face of a die?

Tuesday Mar 10, 2009
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Quantum foundations in the light of gauge theories We will present the conjecture according to which the fact that q and p cannot be both observables'' of the same quantum system indicates that there is a remnant universal symmetry acting on classical states. In order to unpack this claim we will generalize to unconstrained systems the gauge correspondence between properties defined by first-class constraints and gauge symmetries generated by these constraints.

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## Revisiting the scalar sector in Warped Extra Dimensions

Friday Mar 06, 2009
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I will revisit the phenomenology of the radion graviscalar in warped extra dimensions. This particle could be the lightest 'new physics' state to be discovered at the LHC in this type of models. Its phenomenology is very similar to the Standard Model (SM) Higgs, another potentially light scalar particle with which it could actually mix. When SM fields are moved from the boundary to the bulk of the extra dimension, new interesting effects appear in the scalar sector of the model.

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## Introduction to the Bosonic String Part 7B

Friday Mar 06, 2009
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This course provides a thorough introduction to the bosonic string based on the Polyakov path integral and conformal field theory. We introduce central ideas of string theory, the tools of conformal field theory, the Polyakov path integral, and the covariant quantization of the string. We discuss string interactions and cover the tree-level and one loop amplitudes. More advanced topics such as T-duality and D-branes will be taught as part of the course. The course is geared for M.Sc. and Ph.D. students enrolled in Collaborative Ph.D. Program in Theoretical Physics.

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## Introduction to the Bosonic String

Friday Mar 06, 2009
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This course provides a thorough introduction to the bosonic string based on the Polyakov path integral and conformal field theory. We introduce central ideas of string theory, the tools of conformal field theory, the Polyakov path integral, and the covariant quantization of the string. We discuss string interactions and cover the tree-level and one loop amplitudes. More advanced topics such as T-duality and D-branes will be taught as part of the course. The course is geared for M.Sc. and Ph.D. students enrolled in Collaborative Ph.D. Program in Theoretical Physics.

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## Three-dimensional topological sigma-model with boundaries and defects

Thursday Mar 05, 2009
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The Rozansky-Witten model is a topological sigma-model in three dimensions whose target is a hyper-Kahler manifold. Upon compactification to 2d it reduces to the B-model with the same target. Boundary conditions for the Rozansky-Witten model can be regarded as a 3d generalization of B-branes. While branes form a category, boundary conditions in a 3d TFT form a 2-category. I will describe the structure of this 2-category for the Rozansky-Witten model and its connection with a categorification of deformation quantization.

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## Permutational quantum computation and spin networks

Wednesday Mar 04, 2009
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In topological quantum computation the geometric details of a particle trajectory become irrelevant; only the topology matters. This is one reason for the inherent fault tolerance of topological quantum computation. I will speak about a model in which this idea is taken one step further. Even the topology is irrelevant. The computation is determined solely by the permutation of the particles.

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## Mini-Course on Mach's Principle - Lecture 4

Wednesday Mar 04, 2009
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## Next Public Lecture

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

## RECENT PUBLIC LECTURE

### Mario Livio: Brilliant Blunders

Speaker: Mario Livio