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.
In most materials, electrons fill bands, starting from the lowest kinetic energy states. The Fermi level is the boundary between filled states below and empty states above. This is the basis for our very successful understanding of how metals and semiconductors work. But what if all the electrons within a band had the same kinetic energy (this situation is called a "flat band")? Then electrons could arrange themselves so as to minimize their Coulomb repulsion, giving rise to a wide variety of possible states including superconductors and magnets.
Entanglement entropy quantifies the amount of uncertainty of a quantum state. For quantum fields in curved space, entanglement entropy of the quantum field theory degrees of freedom is well-defined for a fixed background geometry. In this work, we propose a generalization of the quantum field theory entanglement entropy by including dynamical gravity.
Understanding galaxy formation is an outstanding problem in Astrophysics. The feedback processes that drive it, exploding stars and accretion onto supermassive black holes, are poorly understood. This results in an order unity uncertainty in the distribution of the gas inside halos, the ``missing baryon problem''. Because baryons are 15% of the total mass in the universe, this baryonic uncertainty is the largest theoretical systematics for percent precision weak lensing surveys like DES, HSC, Rubin Observatory, Roman Observatory and Euclid.
In this talk I will describe a new link "invariant" (with certain wall-crossing properties) for links L in a three-manifold M, where M takes the form of a surface times the real line. This link "invariant" is constructed via a map, called the q-nonabelianization map, from the
Quasars are the most luminous objects in the universe powered by accretion onto supermassive black holes (SMBHs). They can be observed at the earliest cosmic epochs, providing unique insights into the early phases of black hole, structure, and galaxy formation. Observations of these quasars demonstrate that they host SMBHs at their center, already less than ~1 Gyr after the Big Bang.
We will argue that even with semiclassical gravity, it can be shown that a copy of all the information on a Cauchy slice resides near the boundary of the slice. We will first demonstrate this in asymptotically global AdS, and then in four-dimensional asymptotically flat space. We will then describe a physical protocol that can be used to verify this property at low-energies and within perturbation theory.
We reconsider the black hole firewall puzzle, emphasizing that quantum error-correction, computational complexity, and pseudorandomness are crucial concepts for understanding the black hole interior. We assume that the Hawking radiation emitted by an old black hole is pseudorandom, meaning that it cannot be distinguished from a perfectly thermal state by any efficient quantum computation acting on the radiation alone. We then infer the existence of a subspace of the radiation system which we interpret as an encoding of the black hole interior.