# 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.

## Cosmology with Gravitational Lensing

Friday Jan 23, 2009
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## Resolving the information paradox: the fuzzball proposal

Friday Jan 23, 2009
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String theory gives a consistent theory of quantum gravity, so we can ask about the nature of black hole microstates in this theory. Studies of extremal and near-extremal microstates indicate that these microstates do not have a traditional horizon, which would have no data about the microstate in its vicinity. Instead, the information of the microstate is distributed throughout a horizon sized quantum fuzzball'. If this picture holds for all microstates then it would resolve the information paradox.

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## Black holes, fundamental destruction of information and conservation laws

Friday Jan 23, 2009
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Theories which have fundamental information destruction or decoherence are motivated by the black hole information paradox. However they have either violated conservation laws, or are highly non-local. Here, we show that the tension between conservation laws and locality can be circumvented by constructing a relational theory of information destruction. In terms of conservation laws, we derive a generalization of Noether's theorem for general theories, and show that symmetries imply a restriction on the type of evolution permissible.

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## Introduction to the Bosonic String Part B

Friday Jan 23, 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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## Unitarity and Holography in Gravitational Physics

Friday Jan 23, 2009
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Because the gravitational Hamiltonian is a pure boundary term on-shell, asymptotic gravitational fields store information in a manner not possible in local field theories. Two properties follow from this purely gravitational behavior. The first, 'Boundary Unitarity,' holds under AdS-like boundary conditions. This is the statement that the algebra of boundary observables is independent of time; i.e., that the algebra of boundary observables at any one time t_1 in fact coincides with the algebra of boundary observables at any other time t_2.

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## LQG Black Holes

Friday Jan 23, 2009
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In this talk we introduce loop quantum gravity and we apply the theory to the black hole singularity problem. The Schwarzschild black hole solution inside the event horizon coincides with the Kantowski-Sachs space-time and we can study a simple spherically symmetric mini-superspace model. We show the classical black hole singularity is controlled by the quantum theory and the space-time can be dynamically extended beyond the classical singularity. We consider a semiclassical analysis of the black hole in LQG and we focus our attention on the space-time structure.

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## Introduction to the Bosonic String

Friday Jan 23, 2009
Speaker(s):

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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## Ten Theses on Black Hole Entropy

Friday Jan 23, 2009
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I present a viewpoint on black hole thermodynamics according to which the entropy: derives from horizon 'degrees of freedom''; is finite because the deep structure of spacetime is discrete; is `objective'' thanks to the distinguished coarse graining provided by the horizon; and obeys the second law of thermodynamics precisely because the effective dynamics of the exterior region is not unitary.

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## The formation of massive BH seeds at high redshift

Thursday Jan 22, 2009
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TBA

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## A Hamiltonian Formulation of the BKL Conjecture

Thursday Jan 22, 2009
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The BKL Conjecture posits that as one approaches a space-like singularity spatial derivatives become negligible in comparison to temporal derivatives. This idea is explored in a Hamiltonian system adapted for quantization. The resulting classical theory is show to be a series of Bianchi I solutions with Bianchi II transitions, and an approach to quantization is discussed.

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## RECENT PUBLIC LECTURE

### Mario Livio: Brilliant Blunders

Speaker: Mario Livio