General Relativity & Quantum Cosmology

This course offers an introduction to general relativity (GR), focusing on the core principles of Einstein's theory of gravity. We will explore key topics such as the equivalence principle, some essential concepts in differential geometry, the Einstein-Hilbert action, and Einstein's field equations. Furthermore, we will examine practical applications of general relativity in understanding black holes, cosmology, and gravitational waves. Instructor: Ghazal Geshnizjani Students who are not part of the PSI MSc program should review enrollment and course format information here: https://perimeterinstitute.ca/graduate-courses

Recent years have seen a flood of new data, from gravitational wave observations of merging black holes and neutron stars to precision probes of cosmology, which allow for unprecedented tests of our understanding of gravity. Going hand-in-hand with this, there has been significant recent progress on the theoretical side in terms of formulating modified theories of gravity, and using them to make detailed predictions, including in the nonlinear and dynamical regime, which can be confronted with the observations. 

We are excited to announce a landmark conference that plans to delve into the forefront of research on modified theories of gravity and brings together leading experts from different disciplines including observational astrophysicists, numerical relativists, cosmologists and mathematical physicists to explore the present status of modified theories of gravity and envision their future theoretical development and implications for observations.

This conference is also timed to coincide with the 50th anniversary of pioneering work in this area carried out by Gregory Horndeski in the Waterloo Mathematical Physics Community. Hosted jointly by Perimeter Institute and the University of Waterloo, this conference will serve as a forum for researchers from different disciplines to exchange ideas at the cutting
edge of gravitational physics.
 

Presented by:


 

Sponsored in part by Gravity Theory Trust

::  ::  ::

Topics:
• Modified Gravity Theories: Theoretical Framework and Models
• Tests of modified Gravity with Gravitational Waves (LIGO/LISA/PTA)
• Astrophysical/cosmological tests of gravity
• Mathematical structure of Modified gravity
• Observational tests of quantum gravity
• Modified gravity in the early universe

Conference Structure:
The conference will feature a balanced blend of plenary sessions (invited Speakers), contributed talks, panel discussions and poster presentations for students.
• Keynote presentations by renowned physicists in the field, discussing the impact of Horndeski theories and other modified theories of gravity on cosmology, dark energy, and black hole physics.
• Contributed talks: prioritizing early-career researchers
• Panel discussions on emerging research directions, unresolved questions, and potential applications of Horndeski theories.
• Poster sessions for early-career researchers and graduate students to showcase their work and receive feedback from senior scientists.

::  ::  ::

Scientific Organizers:

• Ghazal Geshnizjani (Perimeter Institute, SOC Chair)
• William East (Perimeter Institute)
• Levon Pogosian (Simon Fraser University, Perimeter Institute Affiliate)
• Niayesh Afshordi (Perimeter Institute, U Waterloo, LOC Chair)
• Will Percival (Perimeter Institute, U Waterloo)
• Florian Girelli (U Waterloo, Perimeter Institute Affiliate)
• Jerome Quintin (U Waterloo, Perimeter Institute)
• Alex Krolewski (U Waterloo, Perimeter Institute, CITA)

 

::  ::  ::

This course will introduce some advanced topics in general relativity related to describing gravity in the strong field and dynamical regime. Topics covered include properties of spinning black holes, black hole thermodynamics and energy extraction, how to define horizons in a dynamical setting, formulations of the Einstein equations as constraint and evolution equations, and gravitational waves and how they are sourced.

The course centers on an in-depth study of the symmetry structure of General Relativity and how this is intimately related to its dynamics and to the challenges posed to its quantization. To achieve this understanding, we will introduce a host of concepts and techniques, broadly (and loosely) known under the name of “Covariant Phase Space Method”. This provides a different perspective on GR’s physics, a perspective in which phase space, rather than spacetime, is front and center. We will apply these ideas and techniques to discuss the so-called Problem of Time, Wald's approach to black hole entropy as a Noether charge, and the relationship between Dirac's Hypersurface Deformation Algebra and GR's symmetries and dynamics. We will also discuss the problem of detecting single gravitons as well as crucial analogies and differences between a quantum electromagnetic and gravitational field. Lecture notes specific for the course will be provided.

Review of elementary general relativity. Timelike and null geodesic congruences. Hypersurfaces and junction conditions. Lagrangian and Hamiltonian formulations of general relativity. Mass and angular momentum of a gravitating body. The laws of black-hole mechanics.

Zoom: https://pitp.zoom.us/j/97183751661?pwd=T0szNnRjdUM2dENYNTdmRmJCZVF1QT09

The Gravitational Physics course takes your knowledge and practice of gravity to the next level. We start by recapping the essential elements of differential geometry, adding some new techniques to the toolbox, then apply some of these methods to learning about submanifolds, extra dimensions, and black hole thermodynamics. Towards the end of the course, we delve into the frontiers, with a sample of recent research topics.

Unraveling the quantum nature of gravity is one of the most pressing problems of theoretical physics. Several ideas have been put forward and resulted in a number of theories of quantum gravity. While these theories have explored different facets of the “quantum gravity landscape”, all viable approaches should ultimately make contact with observations, and answer exciting questions in cosmology and black-hole physics.

Sharing knowledge, exchanging ideas, and building a dictionary between different theories are crucial steps toward answering these questions, efficiently contrasting different theories, and ultimately reaching a deeper understanding of our Universe.

This conference will contribute to these goals by bringing together leading experts in different approaches to quantum gravity, gravitational effective field theory, black-hole physics, and cosmology. We will focus on specific puzzles in quantum gravity and their resolutions within different approaches. The conference will be highly interactive, with plenty of time to discuss common problems, understand the big picture, and develop novel connections between fields.

Registration: Registration is now open, and both in-person and virtual participation is welcome. Online participants will be able to interact on an equal footing in question sessions and discussions. In-person attendance is limited and will be approved on a first-come, first-served basis. Talks are by invitation only, but in-person participants are encouraged to apply to present a poster.

Spam warning: There is an increasing number of scam agencies reaching out to conference speakers and attendees. Perimeter Institute does not use third-party agencies. We advise speakers and attendees to ignore emails and not to provide any details to anyone who is not from Perimeter Institute.  

Confirmed Speakers and Panelists:

• Abhay Ashtekar (Penn State University)
• Robert Brandenberger (McGill University)
• Luca Buoninfante (Nordita)
• Xavier Calmet (University of Sussex)
• Francesco di Filippo (Kyoto University)
• Bianca Dittrich (Perimeter Institute)
• John Donoghue (University of Massachusetts)
• Astrid Eichhorn (CP3-origins)
• Johanna Erdmenger (Würzburg University)
• Ghazal Geshnizjani (Perimeter Institute)
• Ruth Gregory (King's College)
• Lavinia Heisenberg (Heidelberg University)
• Bob Holdom (University of Toronto)
• Benjamin Knorr (Nordita)
• Renate Loll (Radboud University Nijmegen)
• Miguel Montero (IFT Madrid)
• Rob Myers (Perimeter Institute)
• Sabrina Pasterski (Perimeter Institute)
• Fernando Quevedo (Cambridge University)
• Lisa Randall (Harvard University)
• Kasia Rejzner (York University)
• Mairi Sakellariadou (King's College)
• Lee Smolin (Perimeter Institute)
• Kellogg Stelle (Imperial College)
• Sumati Surya (Raman Research Institute)
• Andrew Tolley (Imperial College)
• Neil Turok (University of Edinburgh)
• Pedro Vieira (Perimeter Institute)
• Yasaman Yazdi (Imperial College)

 

Territorial Land Acknowledgement

Perimeter Institute acknowledges that it is situated on the traditional territory of the Anishinaabe, Haudenosaunee, and Neutral peoples.

Perimeter Institute is located on the Haldimand Tract. After the American Revolution, the tract was granted by the British to the Six Nations of the Grand River and the Mississaugas of the Credit First Nation as compensation for their role in the war and for the loss of their traditional lands in upstate New York. Of the 950,000 acres granted to the Haudenosaunee, less than 5 percent remains Six Nations land. Only 6,100 acres remain Mississaugas of the Credit land. 

We thank the Anishinaabe, Haudenosaunee, and Neutral peoples for hosting us on their land.

The final meeting of It from Qubit: Simons Collaboration on Quantum Fields, Gravity, and Information will be devoted to recent developments at the interface of fundamental physics and quantum information theory, spanning topics such as

• chaos and thermalization in many-body systems and their realization in quantum gravity;
•  information-theoretic constraints on quantum field theories and their RG flows and symmetries;
• gravitational wormholes and their information-theoretic implications;
• calculable lower-dimensional models of quantum gravity; the entanglement structure of semi-classical states in quantum gravity;
•  quantum error-correcting codes in quantum field theory and quantum gravity;
• complexity in field theory and gravity;
• the black-hole information puzzle;
• quantum simulation of quantum field theories and quantum gravity.

Recorded talks: https://pirsa.org/C23021 

Territorial Land Acknowledgement

Perimeter Institute acknowledges that it is situated on the traditional territory of the Anishinaabe, Haudenosaunee, and Neutral peoples.

Perimeter Institute is located on the Haldimand Tract. After the American Revolution, the tract was granted by the British to the Six Nations of the Grand River and the Mississaugas of the Credit First Nation as compensation for their role in the war and for the loss of their traditional lands in upstate New York. Of the 950,000 acres granted to the Haudenosaunee, less than 5 percent remains Six Nations land. Only 6,100 acres remain Mississaugas of the Credit land. 

We thank the Anishinaabe, Haudenosaunee, and Neutral peoples for hosting us on their land.

This meeting will bring together researchers from the quantum technology, atomic physics, and fundamental physics communities to discuss how quantum simulation can be used to gain new insight into the physics of black holes and the early Universe. The core program of the workshop is intended to deepen collaboration between the UK-based Quantum Simulators for Fundamental Physics (QSimFP; https://www.qsimfp.org) consortium and researchers at Perimeter Institute and neighbouring institutions. The week-long conference will consist of broadly-accessible talks on work within the consortium and work within the broader community of researchers interested in quantum simulation, as well as a poster session and ample time for discussion and collaboration

pirsa.org/C23019

Territorial Land Acknowledgement

Perimeter Institute acknowledges that it is situated on the traditional territory of the Anishinaabe, Haudenosaunee, and Neutral peoples.

Perimeter Institute is located on the Haldimand Tract. After the American Revolution, the tract was granted by the British to the Six Nations of the Grand River and the Mississaugas of the Credit First Nation as compensation for their role in the war and for the loss of their traditional lands in upstate New York. Of the 950,000 acres granted to the Haudenosaunee, less than 5 percent remains Six Nations land. Only 6,100 acres remain Mississaugas of the Credit land. 

We thank the Anishinaabe, Haudenosaunee, and Neutral peoples for hosting us on their land.

On Demand Recording: https://pirsa.org/C23035

The nature of space and time is one of the most foundational mysteries in both Physics and Philosophy. At the heart of this mystery are the two most successful theories of nature: Einstein's theory of relativity, an elegant and precise description of the geometry of our universe on large scales, and Quantum Mechanics, outlining accurate laws of interaction in the subatomic world. But these two great triumphs of 20th century physics remain inherently inconsistent, contradictory in their most basic principles, such as locality and causality. Nonetheless, the experimental domains or natural phenomena where these contradictions become manifest have remained elusive, and it is not clear that a century of theoretical investigation into quantum gravity is anywhere close to being verified in nature.

Arguably, this disconnect is our greatest and most foundational challenge in the history of Physics; despite groundbreaking progress in both theory and observations of quantum spacetimes, these two endeavours are moving farther apart. Successfully responding to this century-old challenge could require rethinking the epistemology of fundamental physics. While physicists are trained to push the frontiers of knowledge, developing a grand vision of the arch of history, and where we are (or should be) heading is a more interdisciplinary endeavor, requiring insights from theory and observations, but also philosophy and history.

We plan a focused, interactive, and highly interdisciplinary workshop, involving the world’s best theorists, observers, experimentalists, and philosophers, within a supportive, inclusive, and diverse environment, in order to kick start a long term initiative that might be our best bet to make significant progress towards uncovering the quantum nature of spacetime.

Sponsorship provided by:

Territorial Land Acknowledgemen

Perimeter Institute acknowledges that it is situated on the traditional territory of the Anishinaabe, Haudenosaunee, and Neutral peoples.

Perimeter Institute is located on the Haldimand Tract. After the American Revolution, the tract was granted by the British to the Six Nations of the Grand River and the Mississaugas of the Credit First Nation as compensation for their role in the war and for the loss of their traditional lands in upstate New York. Of the 950,000 acres granted to the Haudenosaunee, less than 5 percent remains Six Nations land. Only 6,100 acres remain Mississaugas of the Credit land. 

We thank the Anishinaabe, Haudenosaunee, and Neutral peoples for hosting us on their land.

This mini-course of four lectures is an introduction, review, and critique of two approaches to deriving the Einstein equation from hypotheses about horizon entropy. 

It will be based on two papers: 

• "Thermodynamics of Spacetime: The Einstein Equation of State" arxiv.org/abs/gr-qc/9504004
• "Entanglement Equilibrium and the Einstein Equation" arxiv.org/abs/1505.04753

We may also discuss ideas in "Gravitation and vacuum entanglement entropy" arxiv.org/abs/1204.6349

Zoom Link: https://pitp.zoom.us/j/96212372067?pwd=dWVaUFFFc3c5NTlVTDFHOGhCV2pXdz09 

 

There has been recent activity in looking for new conserved charges and symmetries in gravity, most notably at infinity but also for finite regions. An important question is whether some of these charges and symmetries have physical implications. These charges are evaluated on codimension-2 surfaces  called corners, which constitute the main focus of this conference. The goal is to bring together leading experts and promote discussions and exchanges among different approaches to (quantum) gravity. 

https://pirsa.org/C22029

Territorial Land Acknowledgement

Perimeter Institute acknowledges that it is situated on the traditional territory of the Anishinaabe, Haudenosaunee, and Neutral peoples.

Perimeter Institute is located on the Haldimand Tract. After the American Revolution, the tract was granted by the British to the Six Nations of the Grand River and the Mississaugas of the Credit First Nation as compensation for their role in the war and for the loss of their traditional lands in upstate New York. Of the 950,000 acres granted to the Haudenosaunee, less than 5 percent remains Six Nations land. Only 6,100 acres remain Mississaugas of the Credit land. 

We thank the Anishinaabe, Haudenosaunee, and Neutral peoples for hosting us on their land.