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.
We review some recent results on tachyon nonperturbative solutions of the nonlocal, lowest-level, effective action of string field theory. It is shown how nonlocality is encoded in a spacetime diffusion equation and how the latter emerges from the symmteries of the full, background-independent theory.
In 1981 Bill Unruh showed that the equation of motion for sound waves in a
convergent fluid flows is given by a wave equation in an acoustic metric
geometry. More importantly it is possible to set up sonic horizons in
transsonic flows, and thus in principle to mimic experimentally the
I will survey some open problems posed by experiments on condensed matter systems, such as the high temperature superconductors. I will argue that their solutions require analyses of strong-coupling regimes which cannot be addressed by conventional field-theoretic means. I will describe insights drawn from the AdS/CFT correspondence, and discuss the connections to theories with simple gravity duals.