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.
In scalar-tensor gravity, black holes do not obey the Jebsen-Birkhoff theorem. Non-isolated black holes can be highly dynamical and the teleological concept of event horizon is replaced by the apparent or trapping horizon. Dynamical solutions describing inhomogeneities embedded in cosmological "backgrounds" and the phenomenology of their apparent horizons, which often appear/vanish in pairs, will be described. Isolated black holes, in contrast, have no hair and are the same as in general relativity.
We identify a new non-linear neutrino wake effect, due to the streaming motions of neutrinos relative to dark matter, analogous to the Tseliakhovich-Hirata effect. We compute the effect in moving background perturbation theory, compare to direct n-body simulations, and forecast its observability in current and future surveys. Depending on neutrino mass, this effect could be observable in upcoming surveys through a cross correlation dipole in lensing and galaxies.
Quantum information and quantum metrology can be used to study gravitational effects such as gravitational waves and the universality of the equivalence principle. On one hand, the possibility of carrying out experiments to probe gravity using quantum systems opens an avenue to deepen our understanding of the overlap of these theories. On the other hand, incorporating relativity in quantum technologies promises the development of a new generation of relativistic quantum applications of relevance in Earth-based and space-based setups.
The concept of supersymmetry, though never observed in nature, has driven a great deal of research in theoretical physics over the past several decades. Much has been learned through this research, but many unresolved questions remain. This presentation will describe how these questions can lead one down a surprising path: toward the dodecaphony of Austrian composer Arnold Schoenberg.
We provide additional evidence that supersymmetrical quantum mechanical systems can contain a remarkable amount of information about supersymmetrical field
theories in greater than one dimension.
There is a proposed dS/CFT duality in 3+1 dimensions, with higher-spin gravity in the bulk subject to Bunch-Davies boundary conditions. I consider replacing these with antipodally symmetric conditions, which allow for real values of the bulk fields. I present spanning sets of solutions in global dS_4 for free gauge fields of all spins (including photons and gravitons), and use them to establish relations between antipodal symmetry and asymptotic behavior. Some of these relations can be extended to interacting theories, including ordinary and higher-spin gravity.
This talk will try to highlight some basic problems connected with conclusions uncritically drawn from well known works. These include: 1. The Schwarzschild solution 2. The formation of black holes by gravitational collapse 3. The no hair theorem 4. The principle of equivalence in the very early universe.
We consider a closed system where the parameter controlling a quantum phase transition is promoted to a dynamical field interacting with the quantum critical theory. In the case that the field has an energy extensive in the volume we can treat its evolution classically. We find that the field can become trapped near the phase transition point due to its interactions with the degrees of freedom of the quantum critical theory. The trapping/untrapping transition can be understood using Kibble-Zurek scaling arguments.
We will first review the rich variety of universality classes of membranes and the various models developed to describe their mechanical properties. We will then discuss the recent applications of the non-perturbative renormalization group to these models aimed at improving the understanding of the membranes' phase-space beyond the epsilon-expansion. Finally, we will comment on the implications of these results on various physical systems.
To the best of our knowledge, the fundamental laws of physics are Lorentz invariant. This means that condensed matter systems at finite density still display full Lorentz symmetry: it is just spontaneously broken (i.e. by state considered) and thus non-linearly realized. This simple observation allows to derive exact results about the spectrum of theories at finite charge density and suggests to classify condensed matter systems according to all the inequivalent ways in which boosts can be spontaneously broken.