# 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.

## Branes and Quantization

Sunday May 10, 2009

## Symplectic Vortices and a Quantum Kirwan map

Sunday May 10, 2009
Speaker(s):

"A Hamiltonian action of a Lie group on a symplectic manifold $(M,\omega)$ gives rise to a gauge theoretic deformation of the
Cauchy-Riemann equations, called the symplectic vortex equations. Counting solutions of these equations over the complex plane leads to a quantum version of the Kirwan map. In joint work with Christopher Woodward, we interpret this map as a weak morphism of cohomological field theories."

## Groupoids of Connections and Higher-Algebraic QFT

Sunday May 10, 2009
Speaker(s):

This talk will discuss, illustrated by a toy example, how to construct "higher-algebraic" quantum field theories using groupoids. In particular, the groupoids describe configuration spaces of connections, together with their gauge symmetries, on spacetime, space, and boundaries of regions in space. The talk will describe a higher-algebraic "sum over histories", and how this construction is related to usual QFT's, and particularly the relation to the case of the Chern-Simons theory.

## Spaces of Linear Modules on Regular Graded Clifford algebras

Sunday May 10, 2009
Speaker(s):

The space of regular noncommutative algebras includes regular graded Clifford algebras, which correspond to base point free linear systems of quadrics in dimension n in P^n. The schemes of linear modules for these algebras can be described in terms of this linear system. We show that the space of line modules on a 4 dimensional algebra is an Enriques surface called the Reye congruence, and we extend this result to higher dimensions.

## Hamiltonian structure of isomonodromic deformations of rational connections on the Riemann sphere

Sunday May 10, 2009
Speaker(s):

The classical "split" rational R-matrix Poisson bracket structure on the space of rational connections over the Riemann sphere provides a natural setting for studying deformations.

## The Kahler-Ricci flow on Hirzebruch surfaces

Saturday May 09, 2009
Speaker(s):

I will discuss the metric behavior of the Kahler-Ricci flow on Hirzebruch surfaces assuming that the initial metric is invariant under a maximal compact subgroup of the automorphism group. I will describe how, in the sense of Gromov-Hausdorff, the flow either shrinks to a point, collapses to P^1 or contracts an exceptional divisor. This confirms a conjecture of Feldman-Ilmanen-Knopf. This is a joint work with Jian Song.

## Lagrangian mean curvature flow for entire Lipschitz graphs

Saturday May 09, 2009
Speaker(s):

"In this joint work with Jingyi Chen and Weiyong He, we prove
existence of longtime smooth solutions to mean curvature flow of entire
Lipschitz Lagrangian graphs. A Bernstein type result for translating
solitons is also obtained."

## Combinatorics inspired by Donaldson-Thomas theory

Saturday May 09, 2009
Speaker(s):

I will describe some combinatorial problems which arise when computing various types of partition functions for the Donaldson-Thomas theory of a space with a torus action. The problems are all variants of the following: give a generating function which enumerates the number of ways to pile n cubical boxes in the corner of a room. Often the resulting generating functions are nice product formulae, as predicted by the recent wall-crossing formulae of Kontsevich-Soibelman. There are now a variety of techniques, both geometric and combinatorial, to compute these formula.

## Faithfulness of braid group actions on derived categories

Saturday May 09, 2009
Speaker(s):

Inspired by homological mirror symmetry, Seidel and Thomas constructed braid group actions on derived categories of coherent sheaves of various varieties and proved faithfulness of such actions for braid groups of type A. I will discuss joint work with Hugh Thomas giving some faithfulness results for derived braid group actions of types D and E

## Wave equations in Kerr geometry

Saturday May 09, 2009
Speaker(s):

Quite a bit of progress has been achieved over the past seven years in understanding from a rigorous mathematical perspective the long time dynamics of waves in the Kerr geometry of a rotating black hole in equilibrium. A proof of the Penrose process for scalar waves has notably been given in this context. I will review some of these results, obtained in collaboration with Felix Finster, Joel Smoller and Shing-Tung Yau. I will also indicate a number of open problems.

## Next Public Lecture

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## RECENT PUBLIC LECTURE

### Mario Livio: Brilliant Blunders

Speaker: Mario Livio