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.
Black holes are hot! This discovery made by Stephen Hawking ties together gravity, spacetime, quantum matter, and thermal systems into the beautiful and exciting science of "Black Hole Thermodynamics". Its beauty lies in the powerful way it speaks of the unity of physics. The excitement arises because it tells us that there is something lacking in our understanding of spacetime and, at the same time, gives us a major clue as to what the missing ingredient should be.
The parity invariance of spinfoam gravity is an open question. Naively, parity
breaking should reside in the sign of the Immirzi parameter. I show that the
new Lorentzian vertex formula is in fact independent of this sign, suggesting
that the dynamics is parity-invariant. The situation with boundary states and
operators is more complicated. I discuss parity-related pieces of the
transition amplitude and graviton propagator in the large-spin 4-simplex
limit. Numerical results indicate patterns similar to those in the Euclidean
Ideas about information are pervasive, yet the fundamental nature and structure of information - if indeed it has one! - remains elusive. Work done from many different perspectives, including those of physics, biology, logic, computer science, statistics, and game and decision theory, has yielded insights into various aspects of information. Could there be a comprehensive, unified theory?
Correlations in quantum states are sometimes inaccessible if only restricted types of quantum measurements can be performed, an effect known as quantum data hiding. For example highly entangled states shared by two parties might appear uncorrelated if the parties can only measure locally their shares of the state and communicate classically with each other.
We use the mathematical language of sheaf theory to give a unified treatment of non-locality and contextuality, which generalizes the familiar probability tables used in non-locality theory to cover Kochen-Specker configurations and more. We show that contextuality, and non-locality as a special case, correspond exactly to *obstructions to the existence of global sections*.
Cosmic strings are a generic prediction of Grand Unified Theories that can leave a sufficient imprint in the Cosmic Microwave Background anisotropies to open an observational window into an otherwise unreachable high energy domain. Being formed as topological defects of a Higgs field, they are also naturally coupled to various other fields, that can lead to superconducting-like currents, hence radically changing their structure and properties.