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

62 talksCollection Number C16003
Talk


Gravity Basics  1
Veronika Hubeny University of California, Davis

QI Basics  1
Patrick Hayden Stanford University

Entanglement  1
Robert Spekkens Perimeter Institute for Theoretical Physics

GR: Actions and Equations
David Kubiznak Charles University

A new perspective on holographic entanglement
Matthew Headrick Brandeis University

Bell’s Theorem
Adrian Kent University of Cambridge

QFT Basics  1
Thomas Hartman Cornell University


Time in Cosmology
14 talksCollection Number C16016Talk

Welcome and Opening Remarks

Marina Cortes Institute for Astrophysics and Space Sciences

Lee Smolin Perimeter Institute for Theoretical Physics

Neil Turok University of Edinburgh



The origin of arrows of time II

Sean Carroll California Institute of Technology (Caltech)  Division of Physics Mathematics & Astronomy

Marina Cortes Institute for Astrophysics and Space Sciences

Tim Koslowski Technical University of Applied Sciences WürzburgSchweinfurt


The origin of arrows of time II cont.

Sean Carroll California Institute of Technology (Caltech)  Division of Physics Mathematics & Astronomy

Marina Cortes Institute for Astrophysics and Space Sciences

Tim Koslowski Technical University of Applied Sciences WürzburgSchweinfurt


Testing time asymmetry in the early universe

Brian Keating University of California, San Diego

Andrew Liddle University of Lisbon

Richard Muller University of California, Berkeley


The fate of the big bang

Abhay Ashtekar Pennsylvania State University

Neil Turok University of Edinburgh


Time as Organization – Downward Caustation, Structure and Complexity I
Barbara Drossel Technische Universität Darmstadt

Time as Organization – Downward Caustation, Structure and Complexity II

Stuart Kauffman Santa Fe Institute

George Ellis University of Cape Town



Quantum Information in Quantum Gravity II
31 talksCollection Number C15041Talk

Gravity Dual of Quantum Information Metric
Tadashi Takayanagi Yukawa Institute for Theoretical Physics

A new perspective on holographic entanglement
Matthew Headrick Brandeis University

Universal holographic description of CFT entanglement entropy
Thomas Faulkner University of Illinois UrbanaChampaign

Geometric Constructs in AdS/CFT
Veronika Hubeny University of California, Davis

Do black holes create polyamory
Jonathan Oppenheim University College London

Tensor Network Renormalization and the MERA
Glen Evenbly Georgia Institute of Technology

Entanglement renormalization for quantum fields
Jutho Haegeman Ghent University

Holographic quantum errorcorrecting codes: Toy models for the bulk/boundary correspondence
Fernando Pastawski California Institute of Technology



A Novel Perspective on the Continuum Limit in Quantum Gravity
Susanne Schander Perimeter Institute for Theoretical Physics

Probing asymptotically safe quantum gravity with matter
Marc Schiffer Radboud Universiteit Nijmegen

Is Planckian discreteness observable in cosmology?
Alejandro Perez AixMarseille University

Gyroscopic gravitational memory from binary systems
Ali Seraj Université Libre de Bruxelles

The Corners of 1+1 Dimensional Quantum Gravity
Ludovic Varrin National Centre for Nuclear Research (NCBJ)

Quantum Gravity Lecture
Aldo Riello Perimeter Institute for Theoretical Physics

Quantum Gravity Lecture
Aldo Riello Perimeter Institute for Theoretical Physics

Quantum Gravity Lecture
Aldo Riello Perimeter Institute for Theoretical Physics



Quantum Information in Quantum Gravity II
31 talksCollection Number C15041Quantum Information in Quantum Gravity II 
Celestial Holography from Euclidean AdS space.
We will explore the connection between Celestial and Euclidean Antide Sitter (EAdS) holography in the massive scalar case. Specifically, exploiting the socalled hyperbolic foliation of Minkowski spacetime, we will show that each contribution to massive Celestial correlators can be reformulated as a linear combination of contributions to corresponding massive Witten correlators in EAdS. This result will be demonstrated explicitly both for contact diagrams and for the fourpoint particle exchange diagram, and it extends to all orders in perturbation theory by leveraging the bootstrapping properties of the Celestial CFT (CCFT). Within this framework, the KantorovicLebedev transform plays a central role, which will be introduced at the end of the talk. This transform will allow us to make broader considerations regarding nonperturbative properties of a CCFT.

A Novel Perspective on the Continuum Limit in Quantum Gravity
Susanne Schander Perimeter Institute for Theoretical Physics
Some of the most fundamental challenges in quantum gravity involve determining how to take the continuum limit of the underlying regularized theory and how to preserve the causal structure of spacetime. Several approaches to quantum gravity attempt to address these questions, but the technical challenges are substantial.
In this talk, we present a novel approach to a latticeregularized theory of quantum gravity, using techniques from standard lattice quantum field theories to overcome these challenges. Our approach is inspired by quantum geometrodynamics, the earliest attempt at quantizing gravity. While the original approach suffered from the usual shortcomings pertaining to the multiplication of distributions and consequently failed, we propose a novel lattice regularization that is especially well suited for studying the continuum limit. First, we examine the lattice corrections to the theory and quantize these lattice theories in a manner that ensures the manifest causal structure of spacetime. Next, we discuss the constructions involved in obtaining a welldefined continuum limit and explain how our approach can overcome some conceptually unappealing aspects.


Probing asymptotically safe quantum gravity with matter
Marc Schiffer Radboud Universiteit Nijmegen
Asymptotically safe quantum gravity might provide a unified description of the fundamental dynamics of quantum gravity and matter. The realization of asymptotic safety, i.e., of scale symmetry at high energies, constraints the possible interactions and dynamics of a system. In this talk, I will first introduce the scenario of asymptotic safety for gravity with matter, and explain how it can be explored using functional methods. I will then emphasize, how the constraints on the microscopic dynamics of matter arising from quantum scale symmetry can turn into constraints on the gravitational dynamics, both by exploring the asymptotically safe fixedpoint structure, and by exploring resulting infrared physics.


Is Planckian discreteness observable in cosmology?
Alejandro Perez AixMarseille University
A Planck scale inflationary era—in a quantum gravity theory predicting discreteness of quantum geometry at the fundamental scale—produces the scale invariant spectrum of inhomogeneities with very small tensortoscalar ratio of perturbations and a hot big bang leading to a natural dark matter genesis scenario. In this talk I evoke the possibility that some of the major puzzles in cosmology could have an explanation rooted in quantum gravity.


Gyroscopic gravitational memory from binary systems
Ali Seraj Université Libre de Bruxelles
I will review the "gyroscopic gravitational memory”, the permanent effect of gravitational waves on freelyfalling gyroscopes far from the source of gravitational radiation. Then, I will compute the effect created by binary systems in the postNewtonian approximation. The discussion naturally involves the helicity of gravitational waves and gravitational electricmagnetic duality.


The Corners of 1+1 Dimensional Quantum Gravity
Ludovic Varrin National Centre for Nuclear Research (NCBJ)
The concept of symmetries is crucial in our comprehension of modern theoretical physics. The Corner Proposal introduces a novel framework where symmetries are reinstated as foundational principles in our understanding of gravity. This aims to describe gravity using a language that is more adapted to quantization. In this presentation, I will start by providing an overview of the essential results leading to the main ideas the proposal. This will then allow me to state the proposal in the general case to then specialize to 1+1 dimensional gravity.
Finally, I will present elements of our recent research applying the proposal to the case of 1+1 dimensional gravity. I will demonstrate the framework's promising potential by calculating the entanglement entropy between two spatial regions—a significant challenge in quantum gravity. The result is the 1+1 dimensional equivalent of the wellestablished BekensteinHawking area law governing the entropy of gravitational systems with the expected behavior of the quantum corrections.


Quantum Gravity Lecture
Aldo Riello Perimeter Institute for Theoretical Physics

Quantum Gravity Lecture
Aldo Riello Perimeter Institute for Theoretical Physics

Quantum Gravity Lecture
Aldo Riello Perimeter Institute for Theoretical Physics