BLACK-HOLE MICROSTRUCTURE
de
lundi 7 juin 2021 (11:20)
à
vendredi 11 juin 2021 (19:30)
lundi 7 juin 2021
11:20
Connecting. Welcome
Connecting. Welcome
11:20 - 11:30
11:30
How to Spot Microstructure in the Wild
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Daniel Mayerson
How to Spot Microstructure in the Wild
Daniel Mayerson
11:30 - 12:45
The advent of gravitational waves and black hole imaging has opened a new window into probing the horizon scale of black holes. An important question is whether string theory results for black hole physics can predict interesting and observable features that current and future experiments can probe. I will give a brief overview of the relevant observational experiments, before reviewing this exciting new field of gravitational black hole phenomenology from the perspective of fuzzballs. I will discuss what we can learn from the phenomenological study of known fuzzball geometries, what our current limitations are, and how future developments in fuzzballs physics will be crucial for the further development of this field. https://www.youtube.com/watch?v=ghZHE9wX8Kg
13:50
Session Chair: Rodolfo Russo
Session Chair: Rodolfo Russo
13:50 - 14:00
14:00
Black Holes, Unscripted
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Niayesh Afshordi
Black Holes, Unscripted
Niayesh Afshordi
14:00 - 15:00
Black Holes occupy a special place in the fascination of astronomers and physicists. From the most speculative mathematical physicist, to the most sensible radio astronomer, everyone has their own narrative of what lies within a black hole, based on their own preconceptions. As an alternative, I will outline an empirical and agnostic roadmap for probing black hole physics, by combining elements of quantum mechanics, general relativity, and astrophysical observations. http://www.youtube.com/watch?v=fm7r9jJKf3g
15:30
How does a black-hole microstate ringdown?
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Paolo Pani
How does a black-hole microstate ringdown?
Paolo Pani
15:30 - 16:30
The quasinormal-mode spectrum of a horizonless compact object can differ significantly from that of the corresponding classical black hole. However, the time response can be initially very similar if the object is sufficiently compact. A generic smoking gun of the absence of a classical horizon is the presence of echoes in the late-time ringdown. The echo delay time and morphology depend crucially on the properties of the object down to its potential well. Most of the echo analyses so far have considered toy or phenomenological models. I will present recent results on the ringdown phenomenology for a class of multicenter geometries describing the microstates of a static BPS black hole. The numerical method is based on numerical-relativity simulations of a test scalar field propagating on these geometries and can be applied to any stationary microstate, including non-BPS ones. https://youtu.be/cYAoByDykTE
17:15
Panel: Distinguishing Microstructure from Black Holes
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Geoff Penington
Iosif Bena (Moderator)
Daniel Mayerson
Massimo Bianchi
Panel: Distinguishing Microstructure from Black Holes
Geoff Penington
Iosif Bena (Moderator)
Daniel Mayerson
Massimo Bianchi
17:15 - 18:30
Iosif Bena (moderator), Massimo Bianchi, Daniel Mayerson, Geoff Penington https://www.youtube.com/watch?v=0BO-p58Pypc
mardi 8 juin 2021
11:20
Session Chair: Iosif Bena
Session Chair: Iosif Bena
11:20 - 11:30
11:30
Black Hole Microstates in Holography and Worldsheet CFT
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David Turton
Black Hole Microstates in Holography and Worldsheet CFT
David Turton
11:30 - 12:45
In this talk I will review recent progress on two topics. The first topic is the holographic description of heavy configurations in supergravity, in which holography can provide a microscopic interpretation of a supergravity solution as describing a particular pure black hole microstate. Recent results have enabled holographic studies with improved precision for supergravity solutions such as superstrata. The second topic is worldsheet models that describe stringy features of black hole microstates. These features include the fine microstructure of the bound state and an additional time delay of certain probes, beyond that which is visible in supergravity. https://www.youtube.com/watch?v=Z3Qm8BzMyJE
14:00
The CFT Dual of a Tidal Force
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Shaun Hampton
The CFT Dual of a Tidal Force
Shaun Hampton
14:00 - 15:00
It was demonstrated that a string probe falling radially within a superstrata geometry would experience tidal forces. These tidal forces were shown to excite the string by converting its kinetic energy into motion along the transverse directions. Using the AdS/CFT correspondence we seek to understand this behavior from the perspective of the dual D1D5 CFT. To study this process we turn on an interaction of the theory which is described by a deformation operator. This deformation includes a twist operator which joins and separates `effective' strings of the D1D5 system. We start with an initial state which is dual to the probe moving within the superstrata geometry. We then use two deformation operators to compute transition amplitudes between this state and a final state that corresponds to excitations along the transverse directions. We show that for long timescales this amplitude grows as $t^2$ with $t$ being the amount of time for which the deformation operators are turned on. We argue that this process in the CFT is suggestive of the tidal effects experienced by the probe propagating within the dual superstrata geometry. https://youtu.be/DIM5oz3AWHc
15:20
Session Chair: Nejc Ceplak
Session Chair: Nejc Ceplak
15:20 - 15:30
15:30
Black hole microstates vs the additivity conjectures
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Geoff Penington
Black hole microstates vs the additivity conjectures
Geoff Penington
15:30 - 16:30
I will argue that at least one of the following statements must be true: either (a) extensive violations of quantum information theory's “additivity conjectures” exist or (b) there exists a set of “disentangled” black hole microstates that can account for the entire Bekenstein-Hawking entropy (up to at most a subleading O(1) correction). Possibility (a) would be a significant result in quantum communication theory, demonstrating that entanglement can enhance the ability to transmit information much more than has currently been established. More interestingly given the topic of this conference, option (b) would provide new insight into the microphysics of black holes. In particular, the disentangled microstates would have to have nontrivial structure at or outside the black hole horizon, assuming the validity of the quantum extremal surface prescription for calculating entanglement entropy in AdS/CFT. https://youtu.be/fyx4ZHR9N6E
17:15
An overview of Jackiw-Teitelboim gravity and applications
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Joaquin Turiaci
An overview of Jackiw-Teitelboim gravity and applications
Joaquin Turiaci
17:15 - 18:30
We will give an overview of recent developments in two dimensional Jackiw-Teitelboim (JT) gravity in asymptotically AdS, and applications. The talk will be separated into two parts. First we will review perturbative quantum effects in JT gravity, which are a good approximation of low energy physics for a variety of systems including near-extremal black holes in higher dimensions and SYK-like models. These effects become large at small enough temperatures modifying the spectrum and correlators. Still, they are not enough to capture the unitarity of the black hole spectrum. In the second part of the talk, focusing on pure gravity, we will review non-perturbative effects originating from spacetime wormholes and sum over topologies. This leads to a concrete duality between a large class of two dimensional dilaton-gravity theories in asymptotically AdS and a disorder average over boundary Hamiltonians, described by random matrix theory. https://youtu.be/Yjr_k7d2lvE
mercredi 9 juin 2021
11:20
Session Chair: Stefano Giusto
Session Chair: Stefano Giusto
11:20 - 11:30
11:30
Interpolating between multi-center solutions
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Masaki Shigemori
Interpolating between multi-center solutions
Masaki Shigemori
11:30 - 12:30
We study interpolation between two multi-center microstate geometries in 4d/5d that represent Lunin-Mathur geometries with circular profiles. The interpolating solution is a Lunin-Mathur geometry with a helical profile, and is represented by a 2-center solution with a codimension-2 source. The interpolating 2-center solution exhibits interesting features such as some of the charges being delocalized, and some of the charges getting transferred from the codimension-2 center to the other, codimension-3 center as the interpolation proceeds. We also discuss the spectral flow of this entire process and speculate on the relevance of such solutions to understanding general microstates of 3-charge black holes. http://www.youtube.com/watch?v=UakWIQ1dmmU
14:50
Session Chair: Nick Warner
Session Chair: Nick Warner
14:50 - 15:00
15:00
Comments on the Page curve for Hawking radiation
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Juan Maldacena
Comments on the Page curve for Hawking radiation
Juan Maldacena
15:00 - 16:00
We will review the ideas that lead to the computation of the Page curve for Hawking radiation. We will discuss what aspects of the black hole information problem this addresses and which ones remain to be understood. http://www.youtube.com/watch?v=-vHrjKGgtMk
16:00
Contrasting the fuzzball and wormhole paradigms for resolving the black hole information paradox
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Samir Mathur
Contrasting the fuzzball and wormhole paradigms for resolving the black hole information paradox
Samir Mathur
16:00 - 17:00
We summarize the information paradox and how the fuzzball paradigm resolves the paradox. We note that the small corrections theorem implies that any alternative to fuzzballs must involve long-distance nonlocality. We comment on some aspects of the wormhole paradigm, trying to pinpoint the kind of nonlocalities implied by such an approach. https://www.youtube.com/watch?v=-vHrjKGgtMk&t=4215s
17:00
Maldacena Response
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Juan Maldacena
Maldacena Response
Juan Maldacena
17:00 - 17:15
17:15
Mathur Response
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Samir Mathur
Mathur Response
Samir Mathur
17:15 - 17:30
18:15
Panel: Islands
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Samir Mathur
Emil Martinec (Moderator)
Juan Maldacena
Douglas Stanford
Panel: Islands
Samir Mathur
Emil Martinec (Moderator)
Juan Maldacena
Douglas Stanford
18:15 - 19:30
Moderator: Emil Martinec http://www.youtube.com/watch?v=m_1mzZ9tlvc
jeudi 10 juin 2021
14:20
Session Chair: David Turton
Session Chair: David Turton
14:20 - 14:30
14:30
Superstrata and Microstrata
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Nicholas Warner
Superstrata and Microstrata
Nicholas Warner
14:30 - 15:45
I will review that current status of superstrata as a description of BPS microstructure and summarize some of the open problems. I will also describe some new progress in the construction of "microstrata:" non-extremal analogues of superstrata. https://youtu.be/nvPqTqNs00U
16:30
Bubble Bag End: a Non-BPS Floating Brane’s Tale
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Pierre Heidmann
Bubble Bag End: a Non-BPS Floating Brane’s Tale
Pierre Heidmann
16:30 - 17:30
Using the Weyl formalism, we will describe a new mechanism for constructing smooth bubbling geometries in the non-BPS regime. The solutions require at least 6 dimensions, they are static, axially symmetric and asymptotic to four-dimensional Minkowski flat dimensions plus extra compact dimensions. They are generated by a set of harmonic functions like their BPS cousins but are sourced by rods. We will study solutions consisting of a large number of smooth microscopic bubbles, so-called Bubble Bag Ends. These solutions resemble a geometry with a naked singularity that is resolved by the chain of bubbles. The S^2 sphere suddenly opens in the vicinity of the singularity but closes at the bubble loci where the space-time caps off smoothly. We will embed the solutions in string theory and discuss a new non-BPS floating brane Ansatz that allows the construction of static horizonless bubbling geometries. https://youtu.be/CpjWvOLVkoo
18:00
Wormholes and microstructure
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Steve Shenker
Wormholes and microstructure
Steve Shenker
18:00 - 19:00
https://youtu.be/yQ0Q58FvsHM
vendredi 11 juin 2021
13:50
Session Chair: Bogdan Ganchev
Session Chair: Bogdan Ganchev
13:50 - 14:00
14:00
Scrambling in rotating BTZ from CFT
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Ben Craps
Scrambling in rotating BTZ from CFT
Ben Craps
14:00 - 15:00
Slow scrambling has recently been discussed in the context of extremal BTZ black holes and associated microstate geometries. This talk addresses the CFT origin of this phenomenon and of related results for more general rotating BTZ black holes. https://youtu.be/qo8c3xXOvyE
15:25
Session Chair: Daniel Mayerson
Session Chair: Daniel Mayerson
15:25 - 15:30
15:30
AdS3/(worldsheet)CFT2
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Emil Martinec
AdS3/(worldsheet)CFT2
Emil Martinec
15:30 - 16:15
Perturbative string methods provide a wealth of insights into AdS3/CFT2 duality, and its generalization to little string theory. An overview of these methods will be given as well as a survey of results obtained to date. http://www.youtube.com/watch?v=lHjQdvGu-mc
16:45
AdS3 with no BTZs
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Bruno Balthazar
AdS3 with no BTZs
Bruno Balthazar
16:45 - 17:30
I will describe AdS3 string theory with NS fluxes in a regime where the AdS3 radius of curvature is smaller than the string scale. The asymptotic density of states consists of highly excited fundamental strings rather than BTZ black holes. I will present evidence that the CFT dual to this string theory is a symmetric product orbifold with a linear dilaton "block" CFT, with a deformation that introduces a wall that cuts off the strong coupling region. https://youtu.be/Z4r7M6ft1xg
18:00
Panel: Scrambling and Tidal Disruption
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Nicholas Warner (Moderator)
Shaun Hampton
Ben Craps
Julian Sonner
Panel: Scrambling and Tidal Disruption
Nicholas Warner (Moderator)
Shaun Hampton
Ben Craps
Julian Sonner
18:00 - 19:15
https://youtu.be/jHp1WVBdYww