Talks

The Hilbert space of a theory with diffeomorphism symmetry does not factorize into spatial subregions due to gauge constraints. This presents a challenge for defining a notion of entanglement entropy associated with a subregion in these theories. In this talk, I will describe the extended phase space method of Donnelly and Freidel for handling this nonfactorization. It involves introducing edge modes living at the boundary of the subregion, whose purpose is to restore the diffeomorphism invariance that was broken by the subregion's presence. These edge modes are then expected to contribute to the subregion's entanglement entropy. I will further discuss the relevance of the edge mode entanglement to the entropy of black holes, where it may provide a statistical interpretation of the Wald entropy within the low energy effective description.

As a child, Quebec native Pauline Gagnon dreamed of understanding what the universe was really made of.

As an adult, she studied exactly that, working at the largest experiment ever built, CERN’s Large Hadron Collider. In her role as a Senior Research Scientist, based at Indiana University and working at CERN, she searched for dark matter particles in the decays of the famous Higgs boson, in the form of hypothetical particles called dark photons.

Now retired from active research, Gagnon is dedicated to inspiring other curious minds of all ages to ponder the same big questions that fascinated her as a child. Having worked in the CERN Communications group, she is adept at explaining the complex science of particle physics in engaging, comprehensible ways. She has delivered nearly 100 presentations to audiences in nine countries on three continents.

Gagnon’s popular science book, Who Cares about Particle Physics: Making Sense of the Higgs boson, the LHC and CERN, not only explains current issues in particle physics but also explores the importance of fundamental physics in shaping not only our understanding of the universe, but in shaping society as well.

In her Perimeter Institute Public Lecture, Gagnon will explore the incredible (and improbable!) feats of ingenuity and cooperation that have led to one of humanity’s greatest experiments, and why such pioneering research, albeit “useless” in terms of everyday practicality, has changed the way we live and is vital to our collective future.