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10/23/23, 9:00 AM
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John Donoghue10/23/23, 9:10 AM
I will briefly review the key concepts underlying the Effective Field Theory of General Relativity, and give a couple of examples of how it works. Then I will describe seven lessons which can be extracted from the theory. Finally I discuss some of the limitations of the EFT framework.
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Andrew Tolley10/23/23, 9:45 AM
I will briefly review recent progress on how causality/analyticity and unitarity can put powerful constraints on both gravitational and non-gravitational EFTs that admit consistent UV completions.
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Johanna Erdmenger10/23/23, 10:20 AM
I will review implications of the AdS/CFT correspondence for quantum gravity, paying particular attention to holographic RG flows and the processing of information. Deformed hyperbolic geometries correspond to boundary field theory RG flows. Conversely, as I will exemplify using the recent approach of discrete holography, boundary RG flows may be used to reconstruct the bulk spacetime, for...
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Miguel Montero10/23/23, 11:30 AM
At first sight, it seems that almost any QFT, seen as a low-energy effective field theory (EFT), can be coupled to gravity -- simply add an Einstein-Hilbert term, change all derivatives by covariant ones, and you're done. However, a growing body of evidence coming from String Theory compactifications, general properties of black hole evaporation, and rigorous results in holography, suggests...
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Sabrina Pasterski10/23/23, 12:05 PM
The Celestial Holography program encompasses recent efforts to understand the flat space hologram in terms of a CFT living on the celestial sphere. A key development instigating these efforts came from understanding how soft limits of scattering encode infinite dimensional symmetry enhancements corresponding to the asymptotic symmetry group of the bulk spacetime. Historically, the construction...
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John Donoghue, Johanna Erdmenger, Miguel Montero, Sabrina Pasterski, Andrew Tolley10/23/23, 2:00 PM
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John Donoghue, Miguel Montero, Fernando Quevedo, Carlo Rovelli, Andrew Tolley10/23/23, 3:45 PM
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Astrid Eichhorn10/24/23, 9:00 AM
In my talk, I'll review the key idea underlying asymptotically safe quantum gravity, before giving an overview of the current status and open questions. I'll then spotlight three challenges. The first challenge is how to test quantum gravity and I'll advocate that by linking quantum gravity to particle physics and cosmology, we can probe quantum gravity at all scales. The second challenge is...
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Renate Loll10/24/23, 9:35 AM
Based on quantitative results on quantum observables in a Planckian regime, I will argue that using dynamical lattices `a la CDT to construct and explore the nonperturbative path integral over Lorentzian geometries is a bona-fide quantum field-theoretic "method" rather than an "approach" to quantum gravity. Its most important features are universality, unitarity and the presence of powerful...
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Bob Holdom10/24/23, 10:10 AM
A scalar field theory with 4-derivative kinetic terms and 4-derivative cubic and quartic couplings is presented as a proxy for quadratic gravity. Unitarity and positivity appear as the key issues in the scalar field theory, just as they do in quadratic gravity. We have extended some calculations to show how these issues are resolved in the high energy limit of the theory. The results also show...
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Luca Buoninfante10/24/23, 11:15 AM
In the context of perturbative quantum field theory (QFT), the addition of quadratic-curvature invariants to the Einstein-Hilbert action makes it possible to achieve strict renormalizability in four dimensions. This theory exhibits unusual features due to an additional massive spin-2 ghost which, in general, may cause instabilities. In the first part of this talk, we focus on the possibility...
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Benjamin Knorr10/24/23, 11:50 AM
QFT's remarkable success lies in its ability to yield precise predictions through e.g. scattering amplitudes, capturing the essence of running couplings in a gauge-invariant manner. However, the introduction of gravity disrupts this straightforward notion of momentum dependence, posing a significant challenge to our theoretical framework.
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Enter form factors—an ingenious concept that extends... -
Luca Buoninfante, Astrid Eichhorn, Bob Holdom, Benjamin Knorr, Renate Loll10/24/23, 2:00 PM
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Luca Buoninfante, Benjamin Knorr, Kasia Rejzner, Lee Smolin, Pedro Vieira10/24/23, 3:45 PM
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Abhay Ashtekar10/25/23, 9:00 AM
The organizers requested an overview of Loop Quantum Gravity (LQG). However, this is an impossible task, especially for a 30 minute talk, given that the subject is over three decades old with tens of thousands of papers. Instead, I will outline some of the key distinguishing features of LQG and discuss an illustrative application. Hopefully these topics will complement those that will be...
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Sumati Surya10/25/23, 9:35 AM
I will begin with a broad overview of the main ingredients of causal set theory, and then discuss the partial resolution of a long-standing "puzzle" in the causal set path sum. I will then discuss other causal set curiousities, ending with a brief overview of the challenges in constructing a realistic fully non-perturbative quantum dynamics.
The presenter will be joining via Zoom for...
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Pedro Vieira10/25/23, 10:10 AM
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Abhay Ashtekar, Robert Brandenberger, Ghazal Geshnizjani, Mairi Sakellariadou, Yasaman Yazdi10/25/23, 11:15 AM
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Abhay Ashtekar, Sumati Surya, Pedro Vieira10/25/23, 1:45 PM
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Xavier Calmet10/26/23, 9:00 AM
In this talk I present our solution to the information paradox published in Phys.Rev.Lett. 128 (2022) 11, 111301 and Phys.Lett.B 827 (2022) 136995 (see EPL 139 (2022) 4, 49001 for a review). Long wavelength quantum gravitational effects allow the interior state of the black hole to influence Hawking radiation, leading to unitary evaporation. I explain why the Mathur theorem is evaded due to...
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Francesco di Filippo10/26/23, 9:35 AM
Black holes contain, deep in their interior, theoretical evidence of the failure of general relativity. A series of fundamental results, starting from the 1965 Penrose singularity theorem, proved that physically realistic initial conditions will unavoidably produce a singular black hole spacetime. It is generally expected that a full theory of quantum gravity should remove the singularities...
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Ruth Gregory10/26/23, 10:10 AM
One of the fascinating things about Black Hole Thermodynamics is how we often approach it in a very classical fashion, yet - if real - it is an intrinsically quantum phenomenon. I'll use the illustration of thermodynamics of an accelerating black hole to highlight some of these issues, and I'd like to raise questions on how we derive the First Law, and how unique this derivation is.
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Xavier Calmet, Francesco di Filippo, Ruth Gregory10/26/23, 11:15 AM
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10/26/23, 1:10 PM
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Francesco di Filippo, Ruth Gregory, Bob Holdom, Robert Myers, Kelly Stelle10/26/23, 1:30 PM
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Lisa Randall10/26/23, 3:30 PM
Warped extra dimensions were originally introduced as a way of addressing the hierarchy problem. But insights from these scenarios have extended to black hole physics, cosmology, and even mechanisms for addressing issues in purely four dimensions. We investigate this scenario and some compelling lessons.
The presenter will be joining via Zoom for this talk.
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Lavinia Heisenberg10/27/23, 9:00 AM
I will discuss how one can use balance laws in full non-linear general relativity in order to test waveform models (arXiv:2309.12505)
The presenter will be joining via Zoom for this talk.
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Bianca Dittrich10/27/23, 9:35 AM
I will discuss two versions of the simplicial Lorentizian path integral, namely the (Lorentzian) quantum Regge and the spin foam version. I will do so in the simple context of de Sitter cosmology. This simple example will reveal the important role of light cone irregular configurations in the simplicial path integral — I will show that these can either lead to an exponentially enhanced or an...
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Fernando Quevedo10/27/23, 10:10 AM
An overview is given on moduli stabilization in string theory with emphasis in obtaining de Sitter space solutions. Recent work on vacuum transitions will be emphasised.
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Neil Turok10/27/23, 11:15 AM
Recent observations point to a surprisingly economical description of the universe on both very small and very large scales. Stimulated by these findings, Boyle and I have proposed a new, potentially more complete theoretical framework than currently popular paradigms. Our search has so far led to 1) the simplest-yet explanation for the cosmic dark matter, soon to be tested by galaxy surveys,...
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Bianca Dittrich, Lavinia Heisenberg, Fernando Quevedo, Neil Turok10/27/23, 11:50 AM
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Bianca Dittrich, Ruth Gregory, Renate Loll, Mairi Sakellariadou, Sumati Surya10/27/23, 1:45 PM
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Kelly Stelle10/27/23, 3:15 PM
What relations are there between the various ways of wrangling with quantum gravity? String theory is now much more than just a theory of strings -- branes and braneworlds abound. Some kind of effective theory for the familiar world needs to emerge. Are there ways that one could glimpse underlying structure from aspects of an effective theory? That happens for pions -- is there anything like...
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10/27/23, 4:00 PM
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