I describe recent work with with Stefan Hollands that establishes a new criterion for the dynamical stability of black holes in $D \geq 4$ spacetime dimensions in general relativity with respect to axisymmetric perturbations: Dynamic stability is equivalent to the positivity of the canonical energy, $\mathcal E$, on a subspace of linearized solutions that have vanishing linearized ADM mass, momentum, and angular momentum at infinity and satisfy certain gauge conditions at the horizon. We further show that $\mathcal E$ is related to the second order variations of mass, angular momentum, an
We show explicitly how the exact renormalization group equation of interacting vector models in the large N limit can be mapped into certain higher-spin equations of motion. The equations of
motion are generalized to incorporate a multiparticle extension of the higher-spin algebra, which reflects the "multitrace" nature of the interactions in the dual field theory from the holographic point of view.
The direct detection of gravitational waves promises to open up a new spectrum that is otherwise mostly closed to electromagnetically based astronomical observations. Detecting gravitational waves from binary black holes and neutron stars, as well as estimating their parameters, requires a sufficiently accurate prediction for the expected waveform signal.
Commitment to space travel has ebbed and flowed. Physicist Stephen Hawking believes the way to ensure human survival is to continue space exploration. Critics of space travel argue that Planet Earth is in dire need of our attention and resources right now. Is there a trade-off between going to space and fighting climate change, overpopulation and other earthly concerns? Be part of the live studio audience for this special edition of TVO's The Agenda with Steve Paikin.
Quantum Physics. Along with neuroscience and rocket science, it has a reputation of being abstract, inpenetrable and horrendously complicated. Even Einstein himself struggled to get his head around it. But, there’s hope! Using references from movies, books and art, this presentation will guide you through the quantum world and give an overview of science’s best theory of the subatomic world to date. Prepare yourself for a mind-bending journey.
Over the last decade our picture of the universe has changed almost as much as it had in the preceding century. As a result, our picture of the future, both of the universe, and life within it, has dramatically altered as well. This talk will begin by reviewing the recent revolutionary developments in cosmology, and then address several fascinating questions that have arisen as a result of our discovery that the dominant energy of the universe resides in empty space: Can life be eternal in an eternally expanding universe,? Are the laws of physics tailored for the existence of life?
In this talk, I will discuss about the notion of quantum renormalization group, and explain how (D+1)-dimensional gravitational theories naturally emerge as dual descriptions for D-dimensional quantum field theories. It will be argued that the dynamical gravitational field in the bulk encodes the entanglement between low energy modes and high energy modes of the corresponding quantum field theory.