Cosmologists at Perimeter Institute seek to help pin down the constituents and history of our universe, and the rules governing its origin and evolution. Many of the most interesting clues about physics beyond the standard model (e.g., dark matter, dark energy, the matter/antimatter asymmetry, and the spectrum of primordial density perturbations], come from cosmological observations, and cosmological observations are often the best way to test or constrain a proposed modification of the laws of nature, since such observations can probe length scales, time scales, and energy scales that are beyond the reach of terrestrial laboratories.
Format results

2 talksCollection NumberC24037
Talk

Lecture  Relativity, PHYS 604
Perimeter Institute for Theoretical Physics 
Lecture  Relativity, PHYS 604
Perimeter Institute for Theoretical Physics


Future Prospects of Intensity Interferometry
24 talksCollection NumberC24046Talk


Intensity correlations: imaging and quantum optics in astrophysics
The French National Centre for Scientific Research 
Intensity Interferometry with the H.E.S.S. telescopes
ECAP, FAU ErlangenNürnberg 
Progress Toward MultiChannel Intensity Interferometry with the Southern Connecticut Stellar Interferometer
Southern Connecticut State University 

The Multi Aperture Spectroscopic Telescope: Status and potential as an intensity interferometry facility
Weizmann Institute of Science 

Future Astrophysical Targets for Intensity Interferometry
Canadian Institute for Theoretical Astrophysics (CITA)


50 Years of Horndeski Gravity: Exploring Modified Gravity
46 talksCollection NumberC24019Talk



Horndeski Gravity in Cosmology
Leiden University 
How we rediscovered Horndeski gravity
École Normale Supérieure 
Black holes in Horndeski theories
IJCLAB CNRS 
HiCOLA: Horndeski Goes Nonlinear
University of Portsmouth 
Photon Rings and Shadow Size for General AxiSymmetric and Stationary Integrable spacetimes
perimeter institute and university of WaterlooPIRSA:24070086 


Cosmology 2023/24
13 talksCollection NumberC24013Talk

Cosmology Lecture
Perimeter Institute for Theoretical Physics 
Cosmology Lecture
Perimeter Institute for Theoretical Physics 
Cosmology Lecture
Perimeter Institute for Theoretical Physics 
Cosmology Lecture
Perimeter Institute for Theoretical Physics 
Cosmology Lecture
Perimeter Institute for Theoretical Physics 
Cosmology Lecture
Perimeter Institute for Theoretical Physics 
Cosmology Lecture
Perimeter Institute for Theoretical Physics 
Cosmology Lecture
Perimeter Institute for Theoretical Physics


Dark Matter, First Light
26 talksCollection NumberC24015Talk

Opening Remarks

Perimeter Institute for Theoretical Physics

Queen's University


Dark and visible structures with dissipative dark matter
Pennsylvania State University 

Formation of Dark Compact Objects in an Early Matter Dominated Era
Queen's University 
The First Stars in the Universe as Dark Matter Laboratories
Colgate University 
Probing Atomic Dark Matter using Simulated Galactic Subhalo Populations
University of Toronto 
Dark matter at high redshifts with JWST
The University of Texas at Austin 
(Dark) Baryogenesis through Asymmetric Reheating in the Mirror Twin Higgs.
University of Toronto


Puzzles in the Quantum Gravity Landscape: viewpoints from different approaches
34 talksCollection NumberC23033Talk

Lessons of the Effective Field Theory Treatment of General Relativity
University of Massachusetts Amherst 
Positivity Bounds and Effective Fields Theories (A Review)
Imperial College London 
Holography and its implications for quantum gravity  VIRTUAL
University of Würzburg 

Piecing Together a Flat Hologram
Perimeter Institute for Theoretical Physics 
Open Discussion with today's speakers (Donoghue, Erdmenger, Montero, Pasterski, Tolley)

University of Massachusetts Amherst

University of Würzburg

IFT Madrid

Perimeter Institute for Theoretical Physics

Imperial College London


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

University of Massachusetts Amherst

IFT Madrid

University of Cambridge

AixMarseille University

Imperial College London


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


Quantum Simulators of Fundamental Physics
23 talksCollection NumberC23019Talk


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

Five short talks  see description for talk titles

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


First observations of false vacuum decay in a BEC
Newcastle University 
Building Quantum Simulators for QuFTs
Technical University of Vienna 



Quantum Spacetime in the Cosmos: From Conception to Reality
32 talksCollection NumberC23035Talk

Welcome and Opening Remarks
University of Waterloo & Perimeter Institute 
Quantum Gravity and its connection to observations
University of Southern Denmark 

The Spacetime of Acceleration
King's College London 
What is the simplicity of the early universe trying to tell us?
University of Edinburgh 
Are we considering enough? Inclusivity in Quantum Gravity and Cosmology
University of Edinburgh 

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


Quantum Field Theory in Curved Spacetime
7 talksCollection NumberC23031Talk

Quantum Field Theory in Curved Spacetime (AM)  20230303
McMaster University 
Quantum Field Theory in Curved Spacetime (PM)  20230303
McMaster University 
Quantum Field Theory in Curved Spacetime (PM)  20230310
McMaster University 
Quantum Field Theory in Curved Spacetime (PM)  20230317
McMaster University 
Quantum Field Theory in Curved Spacetime (PM)  20230324
McMaster University 
Quantum Field Theory in Curved Spacetime (PM)  20230331
McMaster University 


Horizon entropy and the Einstein equation
4 talksCollection NumberC23029Talk

Horizon entropy and the Einstein equation  Lecture 20230221
University of Maryland, College Park 
Horizon entropy and the Einstein equation  Lecture 20230223
University of Maryland, College Park 
Horizon entropy and the Einstein equation  Lecture 20230228
University of Maryland, College Park 
Horizon entropy and the Einstein equation  Lecture 20230302
University of Maryland, College Park


Quantum Gravity 2020
22 talksCollection NumberC20031Talk

Welcome and Opening Remarks
Perimeter Institute for Theoretical Physics 
Approaches to Quantum Gravity: Key Achievements and Open Issues
MaxPlanckInstitut für Gravitationsphysik 
Quantum gravity from the loop perspective
AixMarseille University 
Lessons for quantum gravity from quantum information theory
Massachusetts Institute of Technology (MIT) 
Understanding of QG from string theory
Princeton University 
Progress in horizon thermodynamics
University of Cambridge 
Asymptotically Safe Amplitudes from the Quantum Effective Action
Radboud Universiteit Nijmegen 
The Remarkable Roundness of the Quantum Universe
Radboud Universiteit Nijmegen


PSI 2019/2020  Cosmology Part 2
2 talksCollection NumberC20015Talk

PSI 2019/2020  Cosmology Part 2  Lecture 1
York University 
PSI 2019/2020  Cosmology Part 2  Lecture 2
York University


Relativity (Core), PHYS 604, November 12  December 11, 2024
2 talksCollection NumberC24037This 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 EinsteinHilbert 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/graduatecourses 
Future Prospects of Intensity Interferometry
24 talksCollection NumberC24046Recent advancements in photodetection technologies and spectroscopy hold the promise of transforming intensity interferometry, thereby revolutionizing observational Astronomy by enabling observations to resolve significantly fainter objects than currently possible. This workshop serves as a platform to unite experts in photodetection, theoretical and observational astronomy, as well as observers and theorists from diverse disciplines, to explore the multifaceted capabilities of intensity interferometry.
The workshop's focus spans three key objectives:
 Develop and disseminate novel ideas concerning science cases unique to intensity interferometry.
 Synthesize insights from observers and photodetector experts concerning the requisite technologies and experimental techniques which will allow for new science with intensity interferometry.
 Initiate a concentrated effort to propel the development of large telescope arrays dedicated to intensity interferometry.
This workshop will be exclusively organized in plenary sessions, providing ample time for engaging discussions among participants.
Scientific Organizers
Masha Baryakhtar  University of Washington
Neal Dalal  Perimeter Institute
Marios Galanis  Perimeter Institute
Junwu Huang  Perimeter Institute 
50 Years of Horndeski Gravity: Exploring Modified Gravity
46 talksCollection NumberC24019Recent 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.
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 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)
:: :: ::

Cosmology 2023/24
13 talksCollection NumberC24013This Cosmology course will provide a theoretical overview of the standard cosmological model.
Topics will include: FRW universe, Thermal History, Inflation, Cosmological Perturbation Theory, Structure Formation and Quantum Initial Conditions. 
Dark Matter, First Light
26 talksCollection NumberC24015New observational programs and techniques are opening a window to the first galaxies in the universe and bringing surprises along the way. In this workshop, we'll explore how dark matter phenomenology may have impacted the first stars and galaxies, focusing on how improved modeling and simulations can allow us to use new and upcoming highredshift data to gain insight into dark matter's fundamental nature.
Sponsored in part by:

Puzzles in the Quantum Gravity Landscape: viewpoints from different approaches
34 talksCollection NumberC23033Unraveling 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.

Quantum Simulators of Fundamental Physics
23 talksCollection NumberC23019This 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 NumberC23035On 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.

Quantum Field Theory in Curved Spacetime
7 talksCollection NumberC23031The course is an introduction to quantum field theory in curved spacetime. Upon building up the general formalism, the latter is applied to several topics in the modern theory of gravity and cosmology where the quantum properties of fundamental fields play an essential role.
Topics to be covered:
1) Radiation of particles by moving mirrors
2) Hawking radiation of black holes
3) Production of primordial density perturbations and gravity waves during inflation
4) Statistical properties of the primordial spectra
Required prior knowledge:
Foundations of quantum mechanics and general relativity 
Horizon entropy and the Einstein equation
4 talksCollection NumberC23029This 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 2020
22 talksCollection NumberC20031 
PSI 2019/2020  Cosmology Part 2
2 talksCollection NumberC20015PSI 2019/2020  Cosmology Part 2