Name: Quantum Gravity 2023
Start: 2023-07-10T08:00:00+02:00
End: 2023-07-14T17:00:00+02:00
Location: Radboud University Nijmegen

Quantum Gravity 2023

from Monday, July 10, 2023 (8:00 AM) to Friday, July 14, 2023 (5:00 PM)

Monday, July 10, 2023

8:00 AM and Information desk
and Information desk
8:00 AM - 8:55 AM
8:55 AM Welcoming Words - Daniele Oriti (LMU Munich) Sijbrand de Jong (Radboud University)
Welcoming Words
- Daniele Oriti (LMU Munich)
- Sijbrand de Jong (Radboud University)
8:55 AM - 9:03 AM
Room: Collegezalencomplex CC2, CC3 & CC5 The event will be opened by Sijbrand de Jong (Dean of the faculty of science). Subsequently Daniele Oriti (chair of the International Society of Quantum Gravity) will welcome the participants.
9:03 AM Common challenges in Quantum Gravity | Review - Bianca Dittrich
Common challenges in Quantum Gravity | Review
- Bianca Dittrich
9:03 AM - 10:00 AM
Room: CC2 I will discuss some of the key challenges in quantum gravity. These will include Lorentzian signature, understanding quantum space-time, explaining our universe and finding signatures of quantum gravity.
10:00 AM Common challenges in Quantum Gravity | Focus: Problem of Time - Claus Kiefer
Common challenges in Quantum Gravity | Focus: Problem of Time
- Claus Kiefer
10:00 AM - 10:30 AM
Room: CC2 The problem of time is among the main conceptual challenges for any approach to quantum gravity. It is already present in classical general relativity, where it is called background independence, but it exhibits its full power only after quantization. I give a general introduction and point out ways for its solution. The presentation is focused on quantum geometrodynamics, which is the canonical quantization of general relativity in metric variables. I give some examples and briefly discuss connected issues such as decoherence, semiclassical approximation, and the arrow of time.
10:30 AM Coffee/tea break
Coffee/tea break
10:30 AM - 11:00 AM
Room: CultuurCafé
11:00 AM Recent developments in String Theory | Review - Ignatios Antoniadis
Recent developments in String Theory | Review
- Ignatios Antoniadis
11:00 AM - 12:00 PM
Room: CC2
12:00 PM Recent developments in String Theory | Focus: From String Landscape and Swampland to Cobordism and Wormholes - Arthur Hebecker (University of Heidelberg)
Recent developments in String Theory | Focus: From String Landscape and Swampland to Cobordism and Wormholes
- Arthur Hebecker (University of Heidelberg)
12:00 PM - 12:30 PM
Room: CC2 I will start with a pedagogical introduction to how the so-called String Landscape arises and what the best candidates for realistic vacua, including in particular cosmic acceleration, are. I will then review how this subject has evolved in view of the recent revival of the Swampland paradigm. Finally, I will comment on the related current topics of Cobordism Conjecture and euclidean wormholes, in particular the various problems associated with the latter.
12:30 PM Lunch
Lunch
12:30 PM - 1:45 PM
Room: De Refter

1:45 PM Posters A
Posters A
1:45 PM - 2:45 PM
Room: Refter (laag)

2:45 PM Coffee/tea break
Coffee/tea break
2:45 PM - 3:15 PM
Room: CultuurCafé
3:15 PM S1
S1
3:15 PM - 5:00 PM
Room: CC3
Contributions

3:15 PM Lorentzian functional renormalization group: Hadamard property and state (in)-dependence. - Rudrajit Banerjee (Okinawa Institute of Science and Technology)

3:30 PM Wave Function Renormalization and Flow of Couplings in Asymptotically Safe Quantum Gravity - Nobuyoshi Ohta (National Central University)

3:45 PM Composite Operators in Asymptotically Safe Quantum Gravity - Maximilian Becker (Radboud University, Nijmegen)

4:00 PM Lorentzian quantum gravity and the graviton spectral function - Manuel Reichert (University of Sussex)

4:15 PM Decoupling limits in Quantum Gravity - Luca Buoninfante (Nordita)

4:30 PM A Phase of 4-dimensional Geometry Generated by Combinatorially Non-local Field Theory - Johannes Thürigen (University of Münster)

4:45 PM High-energy properties of the matter-graviton scattering in quadratic gravity - Yugo Abe (National Institute of Technology, Miyakonojo College)
S2
S2
3:15 PM - 5:00 PM
Room: CC5
Contributions

3:15 PM A discrete discontinuity between the two phases of gravity - Sandipan Sengupta (Indian Institute of Technology Kharagpur)

3:30 PM Radiative correction for the 4D spinfoam model with a cosmological constant - Qiaoyin Pan (Florida Atlantic University)

3:45 PM A new perspective in the construction of spin foam models to quantum gravity - Carlos Beltrán (National Autonomous University of Mexico)

4:00 PM Reviving Quantum Geometrodynamics: Conceptual Setup and Lattice Discretization - Susanne Schander (Perimeter Institute for Theoretical Physics, Canada)

4:15 PM Reviving Quantum Geometrodynamics: Representations of the Kinematical Observables and the Diffeomorphism Group - Thorsten Lang (University of Erlangen–Nuremberg)

4:30 PM Towards new numerical algorithms for spin foam quantum gravity - Sebastian Steinhaus (FSU Jena)

4:45 PM Emergence of geometry from Fluctuations - Marcus Reitz (Jagiellonian University)
5:00 PM Welcome Drinks
Welcome Drinks
5:00 PM - 6:00 PM
Room: CultuurCafé
Tuesday, July 11, 2023

8:30 AM Registration and Information desk
Registration and Information desk
8:30 AM - 9:00 AM
9:00 AM Quantum Gravity in Table-Top Experiments | Review: Theoretical Basis for Low Energy Quantum Gravity and Quantum Information Phenomena - Bei Lok Hu
Quantum Gravity in Table-Top Experiments | Review: Theoretical Basis for Low Energy Quantum Gravity and Quantum Information Phenomena
- Bei Lok Hu
9:00 AM - 10:00 AM
Room: CC2 General relativity and quantum field theory being the two most tested theories which explain exceedingly well the large scale structure and dynamics of spacetime on the one hand and the quantum properties of matter on the other, it is of no surprise that they form the theoretical basis for low energy perturbative quantum gravity experiments. Imposing self-consistency conditions between solutions of the Einstein equation and the field equations for quantum matter leads naturally to semiclassical gravity (SCG). However, when tackling quantum information issues, starting with as simple an entity as the entangled state between two masses (gravitational cat state), Einstein equation sourced by the expectation values of the stress energy tensor of quantum matter fields is inadequate. Correlations or fluctuations of mass densities enter as a necessity. The requisite theory is called stochastic semiclassical gravity. Introduced and constructed in the 90s, rooted in quantum field theory in curved spacetime of the 70s and SCG of the 80s, it has been applied to quantum field processes in the early universe and black holes where fluctuations phenomena are expected to play an important role. In this talk I shall summarize the key features of this theory and show how it, even in the nonrelativistic, weak field form, is needed for treating gravitational decoherence and entanglement problems (part 2), topics of rising current interest, as well as the effect of graviton noises on geodesic separations (part 3), all at experimentally accessible energies. Before that, in deference to the central theme of this conference which is (nonperturbative) quantum gravity, I want to share my view (part 1) and raise some questions of principle in the daunting quest for viable theories describing the microscopic structures of spacetime.
10:00 AM Quantum Gravity in Table-Top Experiments | Focus: How to avoid the appearance of a classical world in gravity experiments? - Hans Hepach (U.of Vienna)
Quantum Gravity in Table-Top Experiments | Focus: How to avoid the appearance of a classical world in gravity experiments?
- Hans Hepach (U.of Vienna)
10:00 AM - 10:30 AM
Room: CC2 No experiment today provides evidence that gravity requires a quantum description. The growing ability to achieve quantum optical control over massive solid-state objects may change that situation – by enabling experiments that directly probe the phenomenology of quantum states of gravitational source masses. This can lead to experimental outcomes that are inconsistent with the predictions of a purely classical field theory of gravity. Such 'Quantum Cavendish' experiments will rely on delocalized motional quantum states of sufficiently massive objects and gravity experiments on the micrometer scale. I review the current status in the lab and the challenges to be overcome for future experiments.
10:30 AM Coffee/tea break
Coffee/tea break
10:30 AM - 11:00 AM
Room: CultuurCafé
11:00 AM Gravity as Quantum Field Theory | Review - J.J. Carrasco
Gravity as Quantum Field Theory | Review
- J.J. Carrasco
11:00 AM - 12:00 PM
Room: CC2
12:00 PM Gravity as Quantum Field Theory | Focus: The road towards non-perturbative gravitational scattering amplitudes in Asymptotic Safety - Benjamin Knorr
Gravity as Quantum Field Theory | Focus: The road towards non-perturbative gravitational scattering amplitudes in Asymptotic Safety
- Benjamin Knorr
12:00 PM - 12:30 PM
Room: CC2 Scattering amplitudes are a key tool of modern quantum field theories, them being used for a wide range of applications, from collider experiments all the way to gravitational waves. In a gravitational context, they showcase the perturbative non-renormalisability of General Relativity: they grow unboundedly at high energies, violating standard unitarity bounds. Any putative quantum gravity theory has to resolve this issue. After a discussion of some general aspects of scattering amplitudes in QFT, I will present some recent advances within Asymptotic Safety to derive non-perturbative gravitational scattering amplitudes from first principles.
12:30 PM Lunch
Lunch
12:30 PM - 1:45 PM
Room: De Refter

Quantum Gravity for Bachelor Students
Quantum Gravity for Bachelor Students
12:30 PM - 1:30 PM
Room: HG00.304

1:45 PM Posters B
Posters B
1:45 PM - 2:45 PM
Room: Refter (laag)

2:45 PM Coffee/tea break
Coffee/tea break
2:45 PM - 3:15 PM
Room: CultuurCafé
3:15 PM S3 - Observables in Quantum Gravity
S3 - Observables in Quantum Gravity
3:15 PM - 5:00 PM
Room: CC3
Contributions

3:15 PM Observables in Quantum Gravity: Observables and dynamical frames in gravity - Philipp Hoehn (OIST)

3:40 PM Observables in Quantum Gravity: Classical observables from quantum scattering amplitudes - Michael Ruf (UCLA)

4:05 PM Algebras and states for quantum fields on causal sets - Christoph Minz (Universität Leipzig, ITP)

4:20 PM Discussion Block
S4 - Lorentzian structures in Quantum Gravity
S4 - Lorentzian structures in Quantum Gravity
3:15 PM - 5:00 PM
Room: CC5
Contributions

3:15 PM Lorentzian Structures in Quantum Gravity: Exploring causality violations in Lorentzian path integrals for discrete gravity - Seth Asante (FSU Jena)

3:40 PM Lorentzian Structures in Quantum Gravity: Calibrating the continuum approximation of discrete quantum gravity - Sumati Surya (Raman Research Institution)

4:05 PM Lorentzian Structures in Quantum Gravity: On the existence of real-time path integrals - Job Feldbrugge (University of Edinburgh)

4:30 PM Discussion Block
7:30 PM Science Café Nijmegen - Outreach Event
Science Café Nijmegen - Outreach Event
7:30 PM - 10:00 PM
Room: Open Air
Wednesday, July 12, 2023

8:30 AM Registration and Information desk
Registration and Information desk
8:30 AM - 9:00 AM
9:00 AM Quantum Gravity Phenomenology I | Review: Are we now really at the dawn of quantum-gravity phenomenology? - Giovanni Amelino-Camelia
Quantum Gravity Phenomenology I | Review: Are we now really at the dawn of quantum-gravity phenomenology?
- Giovanni Amelino-Camelia
9:00 AM - 10:00 AM
Room: CC2 Quantum-gravity phenomenology is entering a more mature phase, especially thanks to the advent of multimessenger astrophysics. For in-vacuo dispersion by photons the CTA and multisatellite gamma-ray telescopes will soon provide data probing higher values of the magnitude of the effects and also suitable for discriminating between different models of the redshift dependence of the effects. IceCube has opened a window on in-vacuo dispersion by neutrinos and tangible improvements in sensitivity will be achieved with KM3NeT, Baikal-GVD and IceCube-Gen2. For the study of Planck-sale-induced threshold anomalies telescopes such as LHAASO should ensure significant progress, by investigating indirectly the inconsistencies presently found among different estimates of the cosmic far-infrared background.The coming years should also bring about meaningful tests of phenomenological models of IR-UV mixing, thanks to improved astrophysics data and even higher accuracy of cold-atom interferometers. This session is shared with the 4th Annual Conference COST CA18108 : Quantum gravity phenomenology in the multi-messenger approach.
10:00 AM Quantum Gravity Phenomenology I | Focus: High precision classical gravitational wave physics from a worldline quantum field theory - Jan Plefka
Quantum Gravity Phenomenology I | Focus: High precision classical gravitational wave physics from a worldline quantum field theory
- Jan Plefka
10:00 AM - 10:30 AM
Room: CC2 This session is shared with the 4th Annual Conference COST CA18108 : Quantum gravity phenomenology in the multi-messenger approach.
10:30 AM Coffee/tea break
Coffee/tea break
10:30 AM - 11:00 AM
Room: CultuurCafé
11:00 AM Quantum Gravity Phenomenology II | Review: Quantum gravity predictions for particle physics and cosmology - Christof Wetterich
Quantum Gravity Phenomenology II | Review: Quantum gravity predictions for particle physics and cosmology
- Christof Wetterich
11:00 AM - 12:00 PM
Room: CC2 Contrary to general belief, the metric fluctuations in quantum gravity can have important consequences for present day experiments in particle physics. The quantum scale symmetry at an ultraviolet fixed point can predict some couplings of the standard model of particle physics. Quantum fluctuations of the metric determine the quartic self-interaction of the Higgs-scalar at an energy scale close to the Planck mass. Extrapolating the running couplings to the electroweak scale, the mass of the Higgs boson has been predicted in the range found later by experiment. Further predictions may concern the quark masses or beyond standard model particles. For cosmology the scaling solution of quantum gravity for scalar potentials is found to have a form that predicts both a very early inflationary epoch and late dynamical dark energy. The spectrum of primordial cosmic fluctuations is, in principle, computable. The beginning of the Universe is typically found to be a scale invariant state that may be called „great emptiness". This session is shared with the 4th Annual Conference COST CA18108 : Quantum gravity phenomenology in the multi-messenger approach.
12:00 PM Quantum Gravity Phenomenology II | Focus: CA18108 network: new challenges and opportunities for research in quantum gravity phenomenology - Jose Manuel Carmona
Quantum Gravity Phenomenology II | Focus: CA18108 network: new challenges and opportunities for research in quantum gravity phenomenology
- Jose Manuel Carmona
12:00 PM - 12:30 PM
Room: CC2 The COST Action CA18108 was established with the aim of fostering the collaboration and synergies among diverse communities interested in the development and astrophysical testing of quantum gravity models. By combining expertises in theoretical models for quantum gravity effects and in the detection of the various cosmic messengers (gamma rays, neutrinos, cosmic rays, and gravitational waves), this network has started to explore exciting challenges in the field of quantum gravity phenomenology. Noteworthy opportunities have arisen since the beginning of the Action, such as the first detection of Gamma Ray Bursts by Imaging Atmospheric Cherenkov Telescopes (IACTs), the discovery of PeVatrons within our galaxy, or the detection of a high-energy neutrino event compatible with the Glashow resonance. These achievements have showcased the potential of the ongoing collaboration between these communities. Together with the upgrades of various instruments, the future holds promising prospects for the exploration of new paths for discovering quantum gravity effects in the physics of the cosmic messengers. This session is shared with the 4th Annual Conference COST CA18108 : Quantum gravity phenomenology in the multi-messenger approach.
12:30 PM Lunch
Lunch
12:30 PM - 1:45 PM
Room: De Refter
Quantum Gravity for Master Students - Mercedes Martinez Benito Laurent Freidel
Quantum Gravity for Master Students
- Mercedes Martinez Benito
- Laurent Freidel
12:30 PM - 1:30 PM
Room: HG00.307 In this talk Mercedes and Laurent will take you through their personal experience with Quantum Gravity, how they themselves came to this topic and what challenges they all face now in their research.
1:45 PM S5
S5
1:45 PM - 3:30 PM
Room: CC3
Contributions

1:45 PM On the canonical equivalence of Jordan and Einstein frames - Gabriele Gionti, S.J. (Specola Vaticana (Vatican Observatory) and LNF-INFN)

2:00 PM Impact of matter fields on quantum geometry - Andrzej Görlich (Jagiellonian U. )

2:15 PM Holographic mappings from quantum gravity states - Simon Langenscheidt

2:30 PM Quantum theory and the maximum compactness of stars. - Ignacio Reyes (University of Amsterdam)

2:45 PM Everpresent Λ Cosmology - Yasaman Yazdi (Imperial College London)

3:00 PM How to constrain the Universe anisotropies across a Big Bounce - Eleonora Giovannetti (CPT Marseille)

3:15 PM The problem of time in quantum cosmology from different approaches - Lucía Menéndez-Pidal (Complutense university)
S6 - Young Researchers session
S6 - Young Researchers session
1:45 PM - 3:30 PM
Room: CC5
Contributions

1:45 PM Alleviation of anomalies from the non-oscillatory vacuum in Loop Quantum Cosmology - Rita Neves (Universidad Complutense de Madrid)

2:00 PM Axion wormhole leading to expanding baby universes - Caroline Jonas (Albert Einstein Institute, Potsdam)

2:15 PM Asymptotic quantum correlations of field modes in time-dependent backgrounds - Sree Mahesh Chandran (Indian Institute of Technology Bombay)

2:30 PM Macroscopic Microscopic Effects from Quantum Gravity - Jesse Daas (Radboud University)

2:45 PM Gaussian states in group field theory and semiclassical properties - Andrea Calcinari (University of Sheffield)

3:00 PM A gauge for graviton fluctuations in the WKB approach - Giulia Maniccia (Sapienza University of Rome, INFN Roma1)

3:15 PM Discussion block
3:30 PM Coffee/tea break
Coffee/tea break
3:30 PM - 4:00 PM
Room: CultuurCafé
4:00 PM S7
S7
4:00 PM - 5:30 PM
Room: CC3
Contributions

4:00 PM Quantum Gravity in de Sitter Space - Suddhasattwa Brahma (Higgs Centre, University of Edinburgh)

4:30 PM Quantum Gravity in de Sitter Space - Thomas Hertog (KU Leuven)

5:00 PM Discussion Block
S8 - Young Researchers session
S8 - Young Researchers session
4:00 PM - 5:30 PM
Room: CC5
Contributions

4:00 PM Young ISQG - Career Panel - Flaminia Giacomini (ETH Zurich) Kasia Rejzner Luca Buoninfante (Nordita) Maximilian Becker (Radboud University, Nijmegen)

5:00 PM Young ISQG - Networking Session
Thursday, July 13, 2023

8:30 AM Registration and Information desk
Registration and Information desk
8:30 AM - 9:00 AM
9:00 AM Loop Quantum Gravity and Spin Foams | Review - Hal Haggard
Loop Quantum Gravity and Spin Foams | Review
- Hal Haggard
9:00 AM - 10:00 AM
Room: CC2 This talk will provide an introduction to Loop Quantum Gravity and Spin Foam models. Loop Quantum Gravity is founded on a gauge-theoretic approach to the quantization of gravity. This approach leverages the huge diffeomorphism invariance of General Relativity to make the Wilson loops of gauge theory into practical probes of spacetime curvature and centers focus on the metrical areas of surfaces, rather than the usual lengths of curves. The simplest example of a loop quantization of geometry is the quantum tetrahedron. I will report on advances connecting classical and quantum tetrahedra to elliptic curves. In addition to the compelling connections with the quantization of geometry and gauge theories, recent years have seen substantial developments in the discrete geometry path integrals known as Spin Foam models. I will overview recent advances in the numerical treatment of these path integrals. This work is demonstrating how these path integrals can be used to address dynamical questions. I will emphasize the multifaceted approach of Loop Gravity, its connections to other approaches to quantum gravity, and some open questions.
10:00 AM Loop Quantum Gravity and Spin Foams | Focus: Quantum Gravitational Dynamics: An Electric Shift in Perspective - Madhavan Varadarajan
Loop Quantum Gravity and Spin Foams | Focus: Quantum Gravitational Dynamics: An Electric Shift in Perspective
- Madhavan Varadarajan
10:00 AM - 10:30 AM
Room: CC2 Classical gravitational evolution in *time* admits an elegant re-expression in terms of of certain generalizations of Lie derivatives with respect to a triple of *spatial* vector fields called the Electric Shift. This property of classical evolution naturally dovetails into a new construction of a quantum dynamics for Euclidean gravity within the canonical quantization approach known as Loop Quantum Gravity (LQG). In my talk I will discuss these new results, their import and avenues for further exploration.
10:30 AM Coffee/tea break
Coffee/tea break
10:30 AM - 11:00 AM
Room: CultuurCafé
11:00 AM Holographic Descriptions of Spacetime | Review - Jan de Boer
Holographic Descriptions of Spacetime | Review
- Jan de Boer
11:00 AM - 12:00 PM
Room: CC2
12:00 PM Holographic Descriptions of Spacetime | Focus: Exactly solvable lower-dimensional gravity models - Thomas Mertens
Holographic Descriptions of Spacetime | Focus: Exactly solvable lower-dimensional gravity models
- Thomas Mertens
12:00 PM - 12:30 PM
Room: CC2 I will discuss three interrelated gravitational models in 1+1 dimensions: Jackiw-Teitelboim (JT) gravity, double-scaled SYK, and Liouville gravity. In spite of their very distinct formulation, I will illustrate that their exact quantum amplitudes show a strong resemblence in terms of the underlying representation theory. This observation can be appreciated upon formulating each of them in terms of a dilaton gravity model, suggesting a modified version of holography for the different models. Based largely on arXiv:2212.07696 and arXiv:2306.00941.
12:30 PM Poster prize ceremony
Poster prize ceremony
12:30 PM - 12:40 PM
Room: Collegezalencomplex CC2, CC3 & CC5

12:40 PM Lunch
Lunch
12:40 PM - 1:45 PM
Room: De Refter
1:45 PM S10
S10
1:45 PM - 3:30 PM
Room: CC5
Contributions

1:45 PM Quantum Gravity meets Cosmology - David Maibach (Heidelberg U.)

2:10 PM Remembrance of Things Past - Richard Woodard (Department of Physics/University of Florida)

2:35 PM The Noise of Gravitons - Maulik Parikh (Arizona State University)

3:00 PM Running relational observables in asymptotically safe gravity - Renata Ferrero (Johannes Gutenberg University Mainz )

3:15 PM Discussion Block
S9
S9
1:45 PM - 3:30 PM
Room: CC3
Contributions

1:45 PM Quantum Black Holes: Covariance in effective models of quantum black holes - David Brizuela (University of the Basque Country)

2:10 PM Quantum Black Holes: Unitarity and quantum resolution of gravitational singularities - Steffen Gielen (University of Sheffield)

2:25 PM Quantum Black Holes: Quantum gravity lessons from black hole thermodynamics - Fil Simovic (Macquarie University)

2:40 PM Quantum Black Holes: Regular black holes and the first law of black hole mechanics - Sebastian Murk (Okinawa Institute of Science and Technology (OIST))

2:55 PM Discussion Block
3:30 PM Coffee/tea break
Coffee/tea break
3:30 PM - 4:00 PM
Room: CultuurCafé
4:00 PM S11
S11
4:00 PM - 5:30 PM
Room: CC3
Contributions

4:00 PM Quantum geometry and entanglement from corner symmetry - Laurent Freidel (Perimeter Institute)

4:30 PM Partition function for a volume of space - Manus Visser (University of Cambridge)

4:45 PM Multipartite Entanglement of Random Spin Networks in Quantum Gravity - Goffredo Chirco (University of Naples Federico II)

5:00 PM Discussion Block
S12
S12
4:00 PM - 5:30 PM
Room: CC5
Contributions

4:00 PM Quantum reference frames: a relational perspective on nonclassical spacetime - Flaminia Giacomini (ETH Zurich)

4:30 PM Observables in Quantum Gravity: UV Effects Mixed into the IR: Observational Signatures of Quantum Gravity - Kathryn Zurek (Caltech)

4:55 PM Understanding Ryu-Takayangi as entropy without invoking holography - Eugenia Colafranceschi (University of California, Santa Barbara)

5:10 PM Discussion Block
7:00 PM Social Dinner
Social Dinner
7:00 PM - 10:00 PM
Friday, July 14, 2023

8:30 AM Registration and Information desk
Registration and Information desk
8:30 AM - 9:00 AM
9:00 AM Causal Structure in Quantum Gravity | Review: Causal Structure in Quantum Gravity - Steve Carlip
Causal Structure in Quantum Gravity | Review: Causal Structure in Quantum Gravity
- Steve Carlip
9:00 AM - 10:00 AM
Room: CC2 Classical spacetimes have Lorentzian metrics, and the resulting light cone structure is crucial to a broad range of results, from singularity theorems to the propagation of gravitational waves. In quantum gravity, though, we expect quantum fluctuations to smear light cones, blurring the causal structure. I will briefly review some of the problems -- and some of the potential benefits -- presented by this blurring, and discuss a few efforts, such as the discrete causal set approach, to address causal structure in quantum gravity.
10:00 AM Causal Structure in Quantum Gravity | Focus: The search for a UV fixed point in four-dimensional CDT - Jan Ambjørn
Causal Structure in Quantum Gravity | Focus: The search for a UV fixed point in four-dimensional CDT
- Jan Ambjørn
10:00 AM - 10:30 AM
Room: CC2 The phase diagram of four-dimensional CDT hints the existence of a UV fixed point which could in principle connect this lattice theory to the asymptotic safety scenario seen by using the functional renormalization group. The present status and future perspectives will be discussed.
10:30 AM Coffee/tea break
Coffee/tea break
10:30 AM - 11:00 AM
Room: CultuurCafé
11:00 AM Field Theory on and of Spacetime | Review - Kasia Rejzner
Field Theory on and of Spacetime | Review
- Kasia Rejzner
11:00 AM - 12:00 PM
Room: CC2
12:00 PM Field Theory on and of Spacetime | Focus: Modern (discrete) 3rd quantization of gravity and emergent cosmology - Daniele Oriti
Field Theory on and of Spacetime | Focus: Modern (discrete) 3rd quantization of gravity and emergent cosmology
- Daniele Oriti
12:00 PM - 12:30 PM
Room: CC2 I recall the old idea of 3rd quantization of gravity, generalizing the gravitational path integral to a sum over topologies, and proceed to illustrate how one could try to make mathematical sense of it, going discrete. I emphasize how this forces to adopt a different perspective, in line with emergent spacetime scenarios. I then introduce tensorial group field theories (TGFTs) for quantum gravity. They are a higher-dimensional generalization of random matrix models (and closely related to lattice quantum gravity and canonical loop quantum gravity), which gave the first concrete realization of the idea of 3rd quantization. Finally, I report on recent results showing the emergence of bouncing cosmologies with late-time cosmic acceleration, from the mean field approximation of quantum geometric TGFT models.
12:30 PM Lunch
Lunch
12:30 PM - 1:45 PM
Room: De Refter
1:45 PM S13
S13
1:45 PM - 2:45 PM
Room: CC2
Contributions

1:45 PM The problem of time in quantum cosmology with a quantum clock - Saeed Rastgoo (University of Alberta)

2:00 PM Towards the phase structure of first order Lorentzian Palatini gravity via Group field theory - Andreas Pithis (LMU Munich)

2:15 PM Scalar cosmological perturbations from full quantum gravity - Luca Marchetti (University of New Brunswick)

2:30 PM General Relativistic Decoherence with Applications to Dark Matter - Mark Hertzberg (Tufts Institute of Cosmology)
S14
S14
1:45 PM - 2:45 PM
Room: CC3
Contributions

1:45 PM Tensor eigenvalue distributions through field theoretical methods - Naoki Sasakura (Yukawa Institute for Theoretical Physics, Kyoto University)

2:00 PM Spinor fields, CPTM symmetry and smallness of cosmological constant in framework of extended manifold - Sergey Bondarenko (Ariel University, Israel)

2:15 PM Invariant observables in quantum gravity and corrections to the Newton potential - Markus B. Fröb (ITP, Universität Leipzig, Germany)

2:30 PM Second law from the Noether current on null hypersurfaces - Antoine Rignon-Bret (Aix-Marseille Université)
S15
S15
1:45 PM - 2:45 PM
Room: CC5
Contributions

1:45 PM Vacuum energy, the Casimir effect, and Newton's non-constant - Benjamin Koch (TU-Wien ITP und Atominstitut)

2:00 PM Loop quantization as a continuum limit: challenges for quantum gravity - Jose A. Zapata (Universidad Nacional Autónoma de México)

2:15 PM Testing The Cosmological Principle In A Quantum Universe - Agustín Silva (Radboud University)

2:30 PM Quantum computations in Loop Quantum Gravity - Grzegorz Czelusta (Jagiellonian University)
2:50 PM Closing Discussion: Round Table
Closing Discussion: Round Table
2:50 PM - 3:40 PM
Room: CC2

3:40 PM Coffee/tea
Coffee/tea
3:40 PM - 4:10 PM
Room: CultuurCafé

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