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

22 talksCollection Number C20031
Talk

Reflections on quantum gravity in 2020
Ted Jacobson University System of Maryland

Random tensors, melonic theories and quantum gravity
Sylvain Carrozza University of Burgundy

Dark Matter meets Quantum Gravity
Manuel Reichert University of Southern Denmark


Virasoro hair and entropy for axisymmetric Killing horizons
Linqing Chen Okinawa Institute of Science and Technology (OIST)

Black hole information, spacetime wormholes, and baby universes
Henry Maxfield University of California

Soft modes in quantum gravity
Monica Pate Harvard University

Free Energy from Replica Wormholes
Netta Engelhardt Massachusetts Institute of Technology (MIT)


PSI 2019/2020  Gravitational Physics
15 talksCollection Number C20004Talk

PSI 2019/2020  Gravitational Physics  Lecture 15
Ruth Gregory King's College London  Department of Mathematics

PSI 2019/2020  Gravitational Physics  Lecture 14
Ruth Gregory King's College London  Department of Mathematics

PSI 2019/2020  Gravitational Physics  Lecture 13
Ruth Gregory King's College London  Department of Mathematics

PSI 2019/2020  Gravitational Physics  Lecture 12
Ruth Gregory King's College London  Department of Mathematics

PSI 2019/2020  Gravitational Physics  Lecture 11
Ruth Gregory King's College London  Department of Mathematics

PSI 2019/2020  Gravitational Physics  Lecture 10
Ruth Gregory King's College London  Department of Mathematics

PSI 2019/2020  Gravitational Physics  Lecture 9
Ruth Gregory King's College London  Department of Mathematics

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


Indefinite Causal Structure
26 talksCollection Number C19049Talk


TBA
Fabio Costa University of Queensland (UQ)

Causality in Qbism
Jacques Pienaar Universität Wien


TBA
Linqing Chen Okinawa Institute of Science and Technology (OIST)

Indefinite causal order without postselection
Katja Ried TNG Technology Consulting

TBA
Robert Mann University of Waterloo

Time reference frames and gravitating quantum clocks
Esteban Castro Ruiz Université Libre de Bruxelles (ULB)


Emmy Noether Workshop: The Structure of Quantum Space Time
25 talksCollection Number C19047Talk

Closing Remarks and GoodBye
Bianca Dittrich Perimeter Institute for Theoretical Physics

Towards inclusion of biology in cosmology
Marina Cortes Institute for Astrophysics and Space Sciences

Central extension and black hole entropy
Linqing Chen Okinawa Institute of Science and Technology (OIST)

Higher spin symmetry in gravity and string
Wei Li Chinese Academy of Sciences  Institute of Theoretical Physics

Evaporating Black Holes in AdS
Netta Engelhardt Massachusetts Institute of Technology (MIT)

How much geometry is in a truncated spectral triple?
Lisa Glaser Universität Wien

Spacetime Foam and the Cosmological Constant
Steve Carlip University of California

AdS/CFT and string sigmamodel nonperturbatively
Valentina Forini City, University of London


Simplicity III
17 talksCollection Number C19044Talk


Fun with path integrals I
Neil Turok Perimeter Institute for Theoretical Physics

Determinism and quantum theory inside black holes
Stefan Hollands Universität Leipzig

Generalized geometry: geometry of unification
Laurent Freidel Perimeter Institute for Theoretical Physics


Pursuing Simplicity with Asymptotic Safety
Roberto Percacci SISSA International School for Advanced Studies

Macroscopic Gravity and the Conformal Anomaly
Emil Mottola Los Alamos National Laboratory

Trinity of Gravity
Lavinia Heisenberg ETH Zurich  Institut für Theoretische Physik


PSI 2019/2020  Relativity (Kubiznak)
15 talksCollection Number C19039Talk

PSI 2019/2020  Relativity (Kubiznak)  Lecture 15
David Kubiznak Perimeter Institute for Theoretical Physics

PSI 2019/2020  Relativity (Kubiznak)  Lecture 14
David Kubiznak Perimeter Institute for Theoretical Physics

PSI 2019/2020  Relativity (Kubiznak)  Lecture 13
David Kubiznak Perimeter Institute for Theoretical Physics

PSI 2019/2020  Relativity (Kubiznak)  Lecture 12
David Kubiznak Perimeter Institute for Theoretical Physics

PSI 2019/2020  Relativity (Kubiznak)  Lecture 11
David Kubiznak Perimeter Institute for Theoretical Physics

PSI 2019/2020  Relativity (Kubiznak)  Lecture 10
David Kubiznak Perimeter Institute for Theoretical Physics

PSI 2019/2020  Relativity (Kubiznak)  Lecture 9
David Kubiznak Perimeter Institute for Theoretical Physics

PSI 2019/2020  Relativity (Kubiznak)  Lecture 8
David Kubiznak Perimeter Institute for Theoretical Physics


PSI 2017/2018  Quantum Gravity (Dupuis)
15 talksCollection Number C17052Talk

PSI 2017/2018  Quantum Gravity  Lecture 15
Laurent Freidel Perimeter Institute for Theoretical Physics

PSI 2017/2018  Quantum Gravity  Lecture 14
Maïté Dupuis Perimeter Institute for Theoretical Physics

PSI 2017/2018  Quantum Gravity  Lecture 13
Maïté Dupuis Perimeter Institute for Theoretical Physics

PSI 2017/2018  Quantum Gravity  Lecture 12
Maïté Dupuis Perimeter Institute for Theoretical Physics

PSI 2017/2018  Quantum Gravity  Lecture 11
Maïté Dupuis Perimeter Institute for Theoretical Physics
PIRSA:18040093 
PSI 2017/2018  Quantum Gravity  Lecture 10
Maïté Dupuis Perimeter Institute for Theoretical Physics

PSI 2017/2018  Quantum Gravity  Lecture 9
Maïté Dupuis Perimeter Institute for Theoretical Physics

PSI 2017/2018  Quantum Gravity  Lecture 8
Maïté Dupuis Perimeter Institute for Theoretical Physics


The Path Integral for Gravity
18 talksCollection Number C17057Talk

Covariant observables and (quantum) extension theorems
Sumati Surya Raman Research Institute

Gravity and Higgs
Ruth Gregory King's College London  Department of Mathematics

Intrinsic and extrinsic points of view
Lucien Hardy Perimeter Institute for Theoretical Physics

The Path Integral of Unmodular Gravity
Roberto Percacci SISSA International School for Advanced Studies

QuantumMechanical Aspects of Quantum Cosmology
Jonathan Halliwell Imperial College London

Why should (and why can) the path integral serve as the basis for quantum theory?
Rafael Sorkin Perimeter Institute for Theoretical Physics

Consistency of a quantum cosmological bounce
Steffen Gielen University of Sheffield

The NoBoundary Proposal: Alive and Well
Thomas Hertog Katholieke Universiteit Leuven


Quantum Black Holes in the Sky?
34 talksCollection Number C17055Talk


What does a quantum black hole look like to the Event Horizon Telescope?
Avery Broderick University of Waterloo


LongLived Inverse Chirp Signals from CoreCollapse in Massive ScalarTensor Gravity
Ulrich Sperhake California Institute of Technology

Growing BlackHole Hair in Extensions of General Relativity
Helvi Witek University of Cambridge

Remarks on cosmic censorship and its possible violations
Roberto Emparan Institucio Catalana de Recerca I Estudis Avancats (ICREA)  Universitat de Barcelona


Qubit Model for Black Hole Evaporation without Firewalls
Don Page University of Alberta


Lights, Sounds, Action in Strong Field Gravity.
Collection Number C17062 
Talk

From 3D TQFTs to 4D models with defects
Bianca Dittrich Perimeter Institute for Theoretical Physics

Hopf algebras and parafermionic lattice models
Joost Slingerland National University of Ireland

Frobenius algebras, Hopf algebras and 3categories
David Reutter Universität Hamburg


The Kitaev model and aspects of semisimple Hopf algebras via the graphical calculus
Tobias Fritz Perimeter Institute for Theoretical Physics


Interacting Hopf monoids and Graphical Linear Algebra
Pawel Sobocinski University of Southampton

Introduction to CQM
Ross Duncan University of Oxford


It from Qubit Summer School
62 talksCollection Number C16003Talk

Toy Holography
Daniel Harlow Massachusetts Institute of Technology (MIT)

Quantum Gravity and Quantum Chaos
Stephen Shenker Stanford University

Why physicists should care about the complexity zoo
Adam Buland Massachusetts Institute of Technology

Eigenstate Thermalization Hypothesis
Markus Müller Institute for Quantum Optics and Quantum Information (IQOQI)  Vienna

Modular hamiltonians in 2d CFT
John Cardy University of California

Tensor Network Holography

Vijay Balasubramanian University of Pennsylvania

Xiaoliang Qi Stanford University

Brian Swingle University of Maryland  College Park


Black Hole Information Paradox  2
Daniel Harlow Massachusetts Institute of Technology (MIT)

Quantum NP and the Complexity of Ground States
Dorit Aharonov Hebrew University of Jerusalem


Quantum Gravity 2020
22 talksCollection Number C20031 
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.

Emmy Noether Workshop: The Structure of Quantum Space Time
25 talksCollection Number C19047Understanding the smallscale structure of spacetime is one of the biggest challenges faced by modern theoretical physics. There are many different attempts to solve this problem and they reflect the diversity of approaches to quantum gravity. This workshop will bring together researchers from a wide range of quantum gravity approaches and give them an opportunity to exchange ideas and gain new insights.

Simplicity III
17 talksCollection Number C19044This crossdisciplinary workshop gathers theorists who have been working on novel approaches to understanding the structure of the Standard Model and its link to cosmology and gravity. It follows the previous Simplicity I and II workshops at Princeton University (2014) and Fermilab (2016) and will be a small informal meeting with plenty of room for discussions.

PSI 2019/2020  Relativity (Kubiznak)
15 talksCollection Number C19039PSI 2019/2020  Relativity (Kubiznak) 
PSI 2017/2018  Quantum Gravity (Dupuis)
15 talksCollection Number C17052PSI 2017/2018  Quantum Gravity (Dupuis) 
The Path Integral for Gravity
18 talksCollection Number C17057Over the past three decades, the idea of a path integral over geometries, describing gravity in various dimensions, has become increasingly central to many areas of theoretical physics, including string and Mtheory, holography and quantum aspects of black holes and cosmology.
In each of these areas, the path integral is frequently invoked as a formal device although, as practitioners will admit, except in very special cases the basic formula remains undefined. Typically, classical saddle points are discussed, whether real or complex, but the required integrals are left unperformed.
This state of affairs is untenable because it leaves the theory on a shaky footing and hence does not permit a sound comparison of theoretical predictions with observations. The time has come to critically reassess the foundational ideas of the path integral for gravity, including its definition, evaluation and interpretation; to identify problems with
existing uses and claims based on it, and to seek improvements. The workshop will focus on the continuum theory and its semiclassical limit, with applications to cosmology, black holes and holography. In particular, the notion of a “Euclidean path integral” for a “wavefunction of the universe” will be addressed.To this effect we intend to revisit discussion of “quantum geometrodynamics” from the path integral viewpoint and to pursue various applications. The developments in this direction that took place in the late 1970's and early 1980's were not incorporated in subsequent efforts, where the emphasis shifted to using a classical background with quantum fluctuations superimposed on it, a split which although useful in particular approximations can hardly be imagined to lie at the foundation of the theory. The revival of the discussion of the foundation of the path integral for gravity is made timely, we believe, by the introduction of new global methods such as PicardLefschetz theory.
The format of the workshop will be unusual. For the first three days, the mornings will begin with a longer, introductory lecture by each of the three organisers, setting out some of the foundational issues. This will be followed by shorter lectures by the participants, tackling the same foundational questions. The morning lectures, held in the Bob room, will be open to all Perimeter residents and visitors. They will be recorded and made available for viewing on PIRSA. Afternoons will be devoted to friendly and informal discussions, with participants invited to offer short contributions which follow up or develop points raised in the mornings, within a relaxed and highly conducive environment. Participation in these afternoon discussion sessions, as well as social events associated with the workshop, will be limited to registered workshop participants. The last two days of the workshop will be an opportunity for participants to continue discussions on topics which emerge as of greatest general interest, as well as to follow up in smaller groups on technical points or new ideas.

Quantum Black Holes in the Sky?
34 talksCollection Number C17055The past decade has witnessed significant breakthroughs in understanding the quantum nature of black holes, with insights coming from quantum information theory, numerical relativity, and string theory. At the same time, astrophysical and gravitational wave observations can now provide an unprecedented window into the phenomenology of black hole horizons. This workshop seeks to bring together leading experts in these fields to explore new theoretical and observational opportunities and synergies that could improve our physical understanding of quantum black holes.

Lights, Sounds, Action in Strong Field Gravity.
Collection Number C17062With LIGO/VIRGO in operation and detecting gravitational waves, the era of gravitational wave astronomy is upon us. In anticipation of further observations, this workshop will discuss the physics, astrophysics, and observational prospectsas well as challengesin gravitational wave sources including black holes, neutron stars, and other fascinating objects, in both the near and long term.

Hopf Algebras in Kitaev's Quantum Double Models: Mathematical Connections from Gauge Theory to Topological Quantum Computing and Categorical Quantum Mechanics
18 talksCollection Number C17029The Kitaev quantum double models are a family of topologically ordered spin models originally proposed to exploit the novel condensed matter phenomenology of topological phases for faulttolerant quantum computation. Their physics is inherited from topological quantum field theories, while their underlying mathematical structure is based on a class of Hopf algebras. This structure is also seen across diverse fields of physics, and so allows connections to be made between the Kitaev models and topics as varied as quantum gauge theory and modified strong complementarity. This workshop will explore this shared mathematical structure and in so doing develop the connections between the fields of mathematical physics, quantum gravity, quantum information, condensed matter and quantum foundations.
