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.
One of the most hotly debated topics of the late nineteenth century concerned the geometry of physical space, an issue that arose with the discovery of non-Euclidean geometries. Lobachevsky and Bolyai opened the way, but it was not until the 1860s that scientists began to take this revolutionary theory seriously. Assuming the free mobility of rigid bodies, Helmholtz concluded that the geometry of space was Euclidean or else of constant curvature (either positive of negative).
What was happening in Philosophy in 1905? This lecture will seek to answer that question by picking out some of the most influential works of philosophy that were published in or shortly before that year, describing both those works themselves and their intellectual context. The works discussed will include Henri Poincare\'s Science and Hypothesis, Edmund Husserl\'s Logical Investigations, Gottlob Frege\'s Fundamental Laws of Arithmetic and Bertrand Russell\'s \'On Denoting\'.
We show that the entropy resulting from the counting of microstates of non extremal black holes using field theory duals of string theories can be interpreted as arising from entanglement. The conditions for making such an interpretation consistent are discussed. First, we interpret the entropy (and thermodynamics) of spacetimes with non degenerate, bifurcating Killing horizons as arising from entanglement. We use a path integral method to define the Hartle-Hawking vacuum state in such spacetimes and discuss explicitly its entangled nature and its relation to the geometry.
In 1905, Norwegian explorer Roald Amundsen completed the first ever transit of the fabled Northwest Passage, culminating a centuries long quest that had claimed ships and lives. Amundsen\'s feat was one of many human achievements in the first decade of the new century, and a landmark in the history exploration. Amundsen\'s voyage was preceded by the controversial North Pole expedition of Robert Peary, another long sought prize of explorers.