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.

 

  

 

Thursday Nov 21, 2019
Speaker(s): 

A spectral triple consists of an algebra, a Hilbert space and a Dirac operator, and if these three fulfill certain relations to each other they contain the entire information of a compact Riemannian manifold.
Using the language of spectral triples makes it possible to generalize the concept of a manifold to include non-commutativity.

 

Thursday Nov 21, 2019
Speaker(s): 

I describe a radical proposal for the cosmological constant problem: perhaps Lambda really is very large, but is "hidden" in Planck-scale fluctuations of geometry and topology. I show that an enormous set of initial data describe a universe with such a hidden cosmological constant at an initial time. The question of whether this structure is preserved under time evolution is still open, but I provide some evidence that it may be. I close with a discussion of open questions that might lead to further insight (or perhaps kill the idea).

 

Thursday Nov 21, 2019
Speaker(s): 

We present a plausible counterexample to the weak cosmic censorship conjecture in four-dimensional Einstein-Scalar theory with asymptotically flat boundary conditions. Our setup stems from the analysis of the massive Klein-Gordon equation on a fixed Kerr black hole background. In particular, we construct the quasinormal spectrum numerically, and analytically in the WKB approximation, then go on to compute its backreation on the Kerr geometry. In the regime of parameters where the analytic and numerical techniques overlap we find perfect agreement.

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Thursday Nov 21, 2019
Speaker(s): 

I will discuss progress on a non-perturbative approach to the study of string sigma-models relevant in AdS/CFT which exploits lattice field theory techniques.

 

Thursday Nov 21, 2019
Speaker(s): 

During this talk we shall discuss the backreaction of quantum matter fields on classical backgrounds by means of the semiclassical Einstein equation.
We shall see that self consistent solutions of this coupled system exist in the case of cosmological spacetimes.
Furthermore, Einstein equations governing the backreaction will transfer quantum matter fluctuations to the metric.
In particular, we will see how the singular structure of quantum matter will affect the spectrum of metric perturbations

 

Thursday Nov 21, 2019
Speaker(s): 

We construct the Haag Kaster net of von Neumann algebras for the Sine-Gordon model. This is joint work with Klaus Fredenhagen and Kasia Rejzner.

 

Wednesday Nov 20, 2019

We show that a generic many-body Hamiltonian can be uniquely reconstructed from a single pair of initial-final states under the unitary time evolution. Interesting it is, this method is not practical due to its high complexity. We then propose a practical method for Hamiltonian reconstruction from multiple pairs of initial-final states. The stability of this method is mathematically proved and numerically verified.

This work is joint with Liujun Zou and Timothy Hsieh.

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Wednesday Nov 20, 2019

Recently they have been generalized to other 3d homogeneous spaces, namely 3d anti de Sitter space and half-pipe space, a 3d homogeneous space with a degenerate metric.

We show that generalized ideal tetrahedra correspond to dual tetrahedra in 3d Minkowski, de Sitter and anti de Sitter space. They are those geodesic tetrahedra whose faces are all lightlike.

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