# 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.

## A natural origin of primordial density perturbations

Tuesday Jun 09, 2009
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We suggest here a mechanism for the seeding of the primordial density fluctuations. We point out that a process like reheating at the end of inflation will inevitably generate perturbations, even on superhorizon scales, by the local diffusion of energy. Provided that the final temperature is of order the GUT scale, the density contrast $\delta_R$ for spheres of radius $R$ will be of order $10^{-5}$ at horizon entry, consistent with the values measured by \texttt{WMAP}.

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## Double Field Theory

Tuesday Jun 09, 2009
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The massless fields of closed string theory on toroidal backgrounds naturally depend on coordinates dual to momentum and coordinates dual to winding. Their dynamical theory, which contains gravitation, must include diffeomorphism and dual diffeomorphism invariance. We begin a serious attempt to construct this generalized form of field theory.

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## Spectral variation of the WMAP 5-year degree scale anisotropy

Monday Jun 08, 2009
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The black body nature of the first acoustic peak of the cosmic microwave background (CMB) was tested using foreground reduced WMAP 5-year data, by producing subtraction maps between pairs of cosmological bands, viz. the Q, V, and W bands, for masked sky areas that avoid the Galactic disk. The resulting maps revealed a non black body signal that has three main properties.

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## Linear Logic for Local Algebras of Observables

Friday Jun 05, 2009
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TBA

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## Discrete Quantum Causal Dynamics

Friday Jun 05, 2009
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We give a mathematical framework to describe the evolution of quantum systems subject to finitely many interactions with classical apparatuus and with each other. The systems in question may be composed of distinct, spatially separated subsystems which evolve independently, but may also interact. The evolution is coded in a mathematical structure in such a way that the properties of causality, covariance and entanglement are faithfully represented.

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## Convex and Categorial Frameworks for Information Processing and Physics

Friday Jun 05, 2009
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TBA

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## Higher-dimensional quantum mechanics

Thursday Jun 04, 2009
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We sketch some ideas about how higher-dimensional categories could be used to extend conventional quantum mechanics. The physical motivation comes from quantum field theory, for which higher-dimensional category theory is very relevant. We discuss how this new approach would affect familiar aspects of quantum theory, such as observables and the Copenhagen interpretation. Few solid answers will be given, but hopefully some discussion will be generated!

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## Towards an abstract description of tensor product

Thursday Jun 04, 2009
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Tensor product is described in a family of categories that includes Set and Hilbert spaces. Such categories admit a "scalar" object which enables a definition of bi-arrows with two domains, generalizing functions of two variables. The tensor product is characterized by the expected universal property relating bi-arrows to arrows.

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## The Group Theoretic Origin of Non-locality for Qubits

Thursday Jun 04, 2009
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TBA

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## Categorical Structures in AQFT

Thursday Jun 04, 2009
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TBA

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## Next Public Lecture

### BRILLIANT BLUNDERS - Mario Livio

Wednesday Jun 01, 2016

## RECENT PUBLIC LECTURE

### Tim Palmer: Climate Change, Chaos and Inexact Computing

Speaker: Tim Palmer