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.
We review recent efforts to turn the cosmological constant into a dynamical variable without an ungainly proliferation of free parameters. In a cosmological setting where parity invariance is imposed (along with homogeneity and isotropy) this leads to phenomenological disaster. However, in this theory it is possible to construct parity violating Friedman models due to torsion, a re-enactment of "Cartan's spiral staircase".
I will discuss a theorem, joint work in progress with Constantin Teleman, in which we characterize which topological 3-dimensional Chern-Simons theories admit nonzero boundary theories. Accepting some physical heuristics, it tells which gapped systems in 2+1 dimensions admit only gapless boundary systems.
The event horizon and the Cauchy horizon of an extremal black hole admit conserved charges associated with scalar perturbations. We will see that these charges are externally measurable from null infinity. This suggests that these charges have the potential to serve as an observational signature for extremal black holes. The proof of this result is based on obtaining precise late-time asymptotics for the radiation field of outgoing perturbations.
Topology illuminates properties of geometric spaces which are independent of scale. Scale-independent features of physical systems play an important role, for example when deducing the large-scale behavior from a small-scale description. After an introduction to basic topological ideas, I will discuss two joint results with Mike Hopkins, one an application to string theory and the other an application to condensed matter theory.