Quantum gravity is concerned with unifying Einstein's general theory of relativity with quantum theory into a single theoretical framework. At Perimeter Institute, researchers are actively pursuing a number of approaches to this problem including loop quantum gravity, spin foam models, asymptotic safety, emergent gravity, string theory, and causal set theory. We are also particularly interested in experimental implications of these different proposals. As the aim is a unification of the laws of physics into a single theory, the search for quantum gravity overlaps with other areas such as cosmology, particle physics and the foundations of quantum theory.
Format results

Collection Number C24019

Quantum Gravity 2023/24
Collection Number C24024 
Puzzles in the Quantum Gravity Landscape: viewpoints from different approaches
34 talksCollection Number C23033Talk

Lessons of the Effective Field Theory Treatment of General Relativity
John Donoghue University of Massachusetts Amherst

Positivity Bounds and Effective Fields Theories (A Review)
Andrew Tolley Imperial College London

Holography and its implications for quantum gravity  VIRTUAL
Johanna Erdmenger University of Würzburg


Piecing Together a Flat Hologram
Sabrina Pasterski Perimeter Institute for Theoretical Physics

Open Discussion with today's speakers (Donoghue, Erdmenger, Montero, Pasterski, Tolley)

John Donoghue University of Massachusetts Amherst

Johanna Erdmenger University of Würzburg

Miguel Mlontero IFT Madrid

Sabrina Pasterski Perimeter Institute for Theoretical Physics

Andrew Tolley Imperial College London


Panel Discussion  Strengths and limitations of EFT (Donoghue, Knorr, Montero, Quevedo, Tolley)

John Donoghue University of Massachusetts Amherst

Miguel Mlontero IFT Madrid

Fernando Quevedo University of Cambridge

Carlo Rovelli Centre de Physique Théorique

Andrew Tolley Imperial College London


Status, perspective and three challenges in the asymptoticsafety paradigm for quantum gravity  VIRTUAL
Astrid Eichhorn University of Southern Denmark


It from Qubit 2023
38 talksCollection Number C23021Talk

Talk 44  Large N von Neumann Algebras and the renormalization of Newton's constant
Elliott Gesteau California Institute of Technology (Caltech)

Talk 88  Type II_1 algebras for local subregions in quantum gravity
Antony Speranza University of Illinois UrbanaChampaign

Talk 124  von Neumann algebras in JT gravity with matter
David Kolchmeyer Massachusetts Institute of Technology

Talk 61  Horizons are Watching You
Gautam Satishchandran 
An SYK model with a scaling similarity.
Juan Maldacena Institute for Advanced Study (IAS)  School of Natural Sciences (SNS)

Petz recovery from subsystems in conformal field theory
Shreya Vardhan Stanford University




Quantum Simulators of Fundamental Physics
23 talksCollection Number C23019Talk


Simulating onedimensional quantum chromodynamics on a quantum computer: Realtime evolutions of tetra and pentaquarks
Christine Muschik Institute for Quantum Computing (IQC)


Five short talks  see description for talk titles

Barbara Soda Perimeter Institute for Theoretical Physics

Dalila Pirvu Perimeter Institute for Theoretical Physics
 Leonardo Solidoro, Pietro Smaniotto, Kate Brown


First observations of false vacuum decay in a BEC
Ian Moss Newcastle University

Building Quantum Simulators for QuFTs
Jorg Schmiedmayer Technical University of Vienna


Language models for simulating the dynamics of quantum systems
Juan Carrasquilla Vector Institute for Artificial Intelligence


Quantum Spacetime in the Cosmos: From Conception to Reality
32 talksCollection Number C23035Talk

Welcome and Opening Remarks
Niayesh Afshordi University of Waterloo & Perimeter Institute

Quantum Gravity and its connection to observations
Astrid Eichhorn University of Southern Denmark


The Spacetime of Acceleration
Ruth Gregory King's College London

What is the simplicity of the early universe trying to tell us?
Latham Boyle University of Edinburgh

Are we considering enough? Inclusivity in Quantum Gravity and Cosmology
Jarita Holbrook University of Edinburgh


Emergent Metric SpaceTime from the BFSS Matrix Model
Robert Brandenberger McGill University  Department of Physics


Horizon entropy and the Einstein equation
4 talksCollection Number C23029Talk

Horizon entropy and the Einstein equation  Lecture 20230221
Ted Jacobson University of Maryland, College Park

Horizon entropy and the Einstein equation  Lecture 20230223
Ted Jacobson University of Maryland, College Park

Horizon entropy and the Einstein equation  Lecture 20230228
Ted Jacobson University of Maryland, College Park

Horizon entropy and the Einstein equation  Lecture 20230302
Ted Jacobson University of Maryland, College Park


Quantum Gravity Around the Corner
29 talksCollection Number C22029Talk

Welcome & Opening Remarks

Celine Zwikel Perimeter Institute for Theoretical Physics

Luca Ciambelli Perimeter Institute for Theoretical Physics


Review Talk: A primer on the covariant phase space formalism
Adrien Fiorucci Technische Universität Wien

Review Talk: A primer on the covariant phase space formalism cont.
Adrien Fiorucci Technische Universität Wien
PIRSA:22100003 
Review Talk: An introduction to coadjoint orbits
Andrea Campoleoni University of Mons

Review Talk: An introduction to coadjoint orbits cont.
Andrea Campoleoni University of Mons

Gong Show

Arnaud Delfante University of Mons

Giovanni Canepa Centre de Physique Théorique

Gloria Odak Centre de Physique Théorique

monireh ahmadpour University of Tehran

Florian Ecker Technische Universität Wien


Local Holography and corner symmetry: A paradigm for quantum gravity
Laurent Freidel Perimeter Institute for Theoretical Physics

Residual gauge symmetries in the front form
Sucheta Majumdar École Normale Supérieure de Lyon (ENS Lyon)


Quantum Gravity 2020
22 talksCollection Number C20031Talk

Welcome and Opening Remarks
Bianca Dittrich Perimeter Institute for Theoretical Physics

Approaches to Quantum Gravity: Key Achievements and Open Issues
Hermann Nicolai MaxPlanckInstitut für Gravitationsphysik

Quantum gravity from the loop perspective
Alejandro Perez Centre de Physique Théorique

Lessons for quantum gravity from quantum information theory
Daniel Harlow Massachusetts Institute of Technology (MIT)

Understanding of QG from string theory
Herman Verlinde Princeton University

Progress in horizon thermodynamics
Aron Wall University of Cambridge

Asymptotically Safe Amplitudes from the Quantum Effective Action
Frank Saueressig Radboud Universiteit Nijmegen

The Remarkable Roundness of the Quantum Universe
Renate Loll Radboud Universiteit Nijmegen


PSI 2019/2020  Quantum Gravity Part 1
6 talksCollection Number C20014Talk

PSI 2019/2020  Quantum Gravity Part 1  Lecture 1
Bianca Dittrich Perimeter Institute for Theoretical Physics

PSI 2019/2020  Quantum Gravity Part 1  Lecture 2
Bianca Dittrich Perimeter Institute for Theoretical Physics

PSI 2019/2020  Quantum Gravity Part 1  Lecture 3
Bianca Dittrich Perimeter Institute for Theoretical Physics

PSI 2019/2020  Quantum Gravity Part 1  Lecture 4
Bianca Dittrich Perimeter Institute for Theoretical Physics

PSI 2019/2020  Quantum Gravity Part 1  Lecture 5
Bianca Dittrich Perimeter Institute for Theoretical Physics

PSI 2019/2020  Quantum Gravity Part 1  Lecture 6
Bianca Dittrich Perimeter Institute for Theoretical Physics


PSI 2019/2020  Gravitational Physics
15 talksCollection Number C20004Talk

PSI 2019/2020  Gravitational Physics  Lecture 1
Ruth Gregory King's College London

PSI 2019/2020  Gravitational Physics  Lecture 2
Ruth Gregory King's College London

PSI 2019/2020  Gravitational Physics  Lecture 3
Ruth Gregory King's College London

PSI 2019/2020  Gravitational Physics  Lecture 4
Ruth Gregory King's College London

PSI 2019/2020  Gravitational Physics  Lecture 5
Ruth Gregory King's College London

PSI 2019/2020  Gravitational Physics  Lecture 6
Ruth Gregory King's College London

PSI 2019/2020  Gravitational Physics  Lecture 7
Ruth Gregory King's College London

PSI 2019/2020  Gravitational Physics  Lecture 8
Ruth Gregory King's College London


Indefinite Causal Structure
26 talksCollection Number C19049Talk


10 years of the quantum SWITCH: state of the art and new perspectives
Giulio Chiribella The University of Hong Kong (HKU)

Cyclic quantum causal models and violations of causal inequalities
Ognyan Oreshkov Université Libre de Bruxelles

TBA
Laura Henderson University of Waterloo

Composing causal orderings
Aleks Kissinger University of Oxford

Quantum principle of relativity
Andrzej Dragan University of Warsaw


What happens when we quantize time?
Alexander Smith Dartmouth College


50 Years of Horndeski Gravity: Exploring Modified Gravity
Collection Number C24019Recent 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 handinhand 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.
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 universeConference 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 earlycareer researchers
• Panel discussions on emerging research directions, unresolved questions, and potential applications of Horndeski theories.
• Poster sessions for earlycareer 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)
:: :: ::

Quantum Gravity 2023/24
Collection Number C24024The course centers on an indepth 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 socalled 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. 
Puzzles in the Quantum Gravity Landscape: viewpoints from different approaches
34 talksCollection Number C23033Unraveling 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 blackhole 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, blackhole 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 inperson and virtual participation is welcome. Online participants will be able to interact on an equal footing in question sessions and discussions. Inperson attendance is limited and will be approved on a firstcome, firstserved basis. Talks are by invitation only, but inperson 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 thirdparty 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 (CP3origins)
 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.

It from Qubit 2023
38 talksCollection Number C23021The 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 manybody systems and their realization in quantum gravity;
 informationtheoretic constraints on quantum field theories and their RG flows and symmetries;
 gravitational wormholes and their informationtheoretic implications;
 calculable lowerdimensional models of quantum gravity; the entanglement structure of semiclassical states in quantum gravity;
 quantum errorcorrecting codes in quantum field theory and quantum gravity;
 complexity in field theory and gravity;
 the blackhole 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.

Quantum Simulators of Fundamental Physics
23 talksCollection Number C23019This 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 UKbased Quantum Simulators for Fundamental Physics (QSimFP; https://www.qsimfp.org) consortium and researchers at Perimeter Institute and neighbouring institutions. The weeklong conference will consist of broadlyaccessible 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
Territorial Land AcknowledgementPerimeter 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.

Quantum Spacetime in the Cosmos: From Conception to Reality
32 talksCollection Number C23035On 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 centuryold 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 AcknowledgemenPerimeter 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.

Horizon entropy and the Einstein equation
4 talksCollection Number C23029This minicourse 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/grqc/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

Quantum Gravity Around the Corner
29 talksCollection Number C22029There 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 codimension2 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.
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.

Quantum Gravity 2020
22 talksCollection Number C20031 
PSI 2019/2020  Quantum Gravity Part 1
6 talksCollection Number C20014PSI 2019/2020  Quantum Gravity Part 1 
PSI 2019/2020  Gravitational Physics
15 talksCollection Number C20004PSI 2019/2020  Gravitational Physics 
Indefinite Causal Structure
26 talksCollection Number C19049There has been a surge of interest in indefinite causal structure the idea that cause and effect can no longer be sharply distinguished. Motivated both by experimentation with quantum switches and quantum gravity there can be situations in which there is no matterofthefact as to what the causal structure of spacetime is. This meeting will bring together workers in Quantum Foundations and Quantum Gravity in both theoretical experimental physics to discuss the state of the art of current research and set new directions for this emerging subdiscipline.