View count: 93

Abstract

Chong-Sun Chu (NTHU)
"A Proposal for a Quantum Mechanical Model of Black Hole"
Black holes pose sharp consistency questions at the interface of gravity, quantum mechanics, and thermodynamics. It is widely believed that resolving problems such as providing a microscopic account of Bekenstein–Hawking entropy, understanding the origin of black hole thermodynamics, and resolving the information paradox posed by Hawking radiation will provide valuable insights to the construction of the theory of quantum gravity.
In this talk, I discuss a recent proposal [1,2] of a quantum mechanics of quantized space as a model of quantum black hole and quantum gravity in 4-dimensions. Our construction was motivated by the bottom-up approach [3,4]. As a system of quantum bits of quantum space, our model reproduces not only the needed macroscopic properties of the Schwarzschild black hole [1] and the rotating Kerr black hole [2], it also provides a microscopic counting of the Bekenstein-Hawking entropy of black hole [1,2] and explains the origin of Hawking radiation in terms of a tunneling process of emission of monopole in the quantum mechanics [5].
As application, I discuss how the well-known membrane paradigm of black hole is modified by quantum gravity effects [6]. In classical general relativity, the black hole membrane is an electrical conductor with a constant vacuum resistivity. We identify new quantum gravity effects and show that the quantum black hole membrane has also a frequency dependent inductance and a chiral Hall conductance. We propose to test these new effects with the observation of quasi-normal modes.

1. Matrix model proposal for quantum gravity and the quantum mechanics of black holes, Phys.Rev.D 112 (2025) 6, 066001, Chong-Sun Chu
2. Quantum Kerr black hole from matrix theory of quantum gravity, Phys.Rev.D 112 (2025) 4, 046014, Chong-Sun Chu
3. Fermi model of a quantum black hole, Phys.Rev.D 110 (2024) 4, 046001, Chong-Sun Chu
4. Tunneling of Bell particles, page curve and black hole information, Phys.Lett.B 865 (2025) 139486, Chong-Sun Chu
5. Hawking Radiation from Tunneling in Black Hole Quantum Mechanics, e-Print: 2603.12199 [hep-th], Chong-Sun Chu
6. Membrane Paradigm for Quantum Black Hole, to appear, Chong-Sun Chu

KEYWORDS
Quantum gravity, Quantum black hole, Information paradox, Membrane paradigm, Quasi-normal modes.
Sumit Das (Kentucky)
"Comments on Target Space Entanglement"
Understanding the role of entanglement in holography requires an understanding of notions of entanglement in the target space of field theories. I will review gauge invariant notions of target space entanglement which have been proposed in recent years and some results which have been obtained so far.
Pei-Ming Ho (NTU)
"Hawking radiation after the scrambling time"
I will explain why UV physics becomes relevant for the prediction of Hawking radiation after the scrambling time, and how certain UV physics, in particular those leading to a spacetime uncertainty relation, suppresses or even terminates Hawking radiation.
Emil Martinec (Chicago)
TBA
Samir Mathur (Ohio State U)
"Introduction to the black hole information paradox"
"Contrasting the fuzzball and wormhole paradigms"
"Introduction to the black hole information paradox"
We will begin from first principles and introduce the information puzzle in simple language. We will explain the important features of the black hole geometry that lead to the problem. We will use a simplified model using coupled harmonic oscillators to explain the phenomenon of Hawking radiation, and how it leads to a rising entanglement between the radiation and the remaining hole.
 
"Contrasting the fuzzball and wormhole paradigms"
We will explain how in string theory the puzzle is resolved by the fuzzball paradigm. We will explain some common confusions about fuzzballs, which have prevented wider acceptance of fuzzballs as the resolution of the problem. We will discuss an alternative resolution which has been proposed – the wormhole paradigm. We will note that here are several different sets of beliefs mixed together in this approach, with some arguments being circular. We will see that the noncircular arguments amount to  requiring long-distance nonlocal Hamiltonian effects in the theory; such effects have not been found so far in string theory.
Yuki Yokokura (Kochi University of Technology)
"Semi-Classical Dynamics of Evaporating Black Holes and the Emergence of a Quantum Gravity Phase"
One natural approach to resolving the information problem is to fundamentally rethink what a black hole is. First, we present a self-consistent, non-perturbative analysis of the 4D semi-classical Einstein equations for the time evolution of spherically-symmetric collapsing matter incorporating the backreaction of evaporation. The solution shows that the matter evolves into a horizonless dense compact object, where 4D quantum fluctuation generates Hawking-like radiation and a quantum pressure. Integrating the entropy density over the bulk volume reproduces the Bekenstein-Hawking formula. Next, we discuss the physical limitation of this semi-classical description. As the curvature is close to the Planck scale, the interior spacetime geometry is barely semi-classical, yet it is already in the regime of quantum gravity; it breaks down at the O(1) level. To understand the true picture of this object, we propose a perspective where spacetime transitions into a non-geometrical quantum-gravitational state—the curvature condensation phase. In this light, a black hole would be ultimately revealed not as a region of geometry, but as a localized phase of quantum gravity.