"Quantum Gravity and All of That" seminar series is aimed at bringing together experts, postdocs and students working on the following topics:
Quantum gravity and strings, including the early Universe scenarios
Quantum gravity and black holes
Information paradox
Holography and AdS/CFT, including holography and complexity, holography and neutron star physics
Quantum information, including the information theory
and related subjects, including gravitational waves from compact objects and phase transitions.
The seminars are expected to have about 1 hour for the main talk and 30+ minutes for discussions. We pay a special account for open discussions and exchange of opinions as the main driving force in our research community. The principal schedule is one seminar per two weeks on Thursdays at 16:00 CET (or CEST) time. This may be occasionally adjusted to account special time requests of speakers.
The seminars and afterwards discussions will be zoom-based. You have to register following the Registration link above to be included in the mailing list. Talk proposals and other inquires can be submitted through the seminar e-mail (see below).
As a rule of thumb in most cases we would have a 1 hour talk followed by a 30+ minutes of the discussion session.
Moreover, given speaker permissions, talks will be recorded and uploaded to the YouTube Channel.
Thursday, January 15, 2026, 15:00 CET (06:00 Los Angeles, 09:00 New York, 17:00 Moscow, 22:00 Shanghai, 23:00 Tokyo)
Title: Global Symmetries in Entanglement Islands
Speaker: Hao Geng (Harvard U.)
Abstract:
A central conjecture in quantum gravity is the non-existence of global symmetries. As a fully unitary theory, there is no information loss in a UV complete quantum gravity theory. We see both these concepts reflected in the AdS/CFT correspondence, which tells us that dynamical processes in AdS are fully captured by a manifestly unitary CFT with no information loss. Furthermore, global symmetries of the CFT are dual to gauge symmetries in the AdS, which implies no global symmetry in the AdS. In this work, we provide concrete evidence for the connection between the non-existence of global symmetries and the absence of information loss in quantum gravity. We study the island setups in which a gravitational AdS is coupled with a nongravitational bath on its boundary. In such theories, the information in the AdS can be lost to the bath. We provide concrete examples with global symmetries in the island setup, from both the bottom-up and the top-down perspectives. We argue that these global symmetries are consistent due to entanglement islands, in which holography is realized in a novel fashion. The global symmetries we construct are all mixed with spontaneously broken gauge symmetries. We will show that this fact has two implications:
1)The black hole hair is detectable in the bath (``wet hair");
2) a resolution of a puzzle proposed by Harlow and Shagoulian.
The registration is open to anyone interested in attending the talks and participating in the discussion sessions.
The registration is required to better maintain the seminars.
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Below is the reasonably up-to-date list of the registered seminar series participants.
We strive to keep it actual but we do process registrations manually in a bid to eliminate unwanted mistakes.
You are welcome to contact the Organizers if you notice any inconsistency regarding the above list.
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