Joint ICTP/SISSA Statistical Physics Seminar, 1 July at 11:00am, by G. Bianconi

[CMSP Seminars Secretariat]

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Joint ICTP/SISSA Statistical Physics Seminar
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** * * Tuesday 1 July**2025, 11:00**am ***(CET)** * **
*Lagrange Lecture Hall **(Leonardo Building)***
**
/Zoom: 
https://zoom.us/meeting/register/gZHSwG36TTmW1SZjnxKikw/<https://zoom.us/meeting/register/tJIsfuuhqjsrE9EZY2loNxNobg8Lf39NUVHJ>

Speaker:*Ginestra Bianconi *(Queen Mary University of London)

Title: *Gravity from entropy
*

Abstract:
Gravity is derived from an action given by the geometrical quantum 
relative entropy coupling matter fields with geometry. The fundamental 
idea is to relate the metric of Lorentzian spacetime to a quantum 
operator, playing the role of an renormalizable effective density matrix 
and to describe the matter fields topologically, according to a 
Dirac-Kähler formalism, as the direct sum of a 0-form, a 1-form and a 
2-form. While the geometry of spacetime is defined by its metric, the 
matter fields can be used to define an alternative metric, the metric 
induced by the matter fields, which geometrically describes the 
interplay between spacetime and matter. The proposed entropic action is 
the geometric quantum relative entropy between the metric of spacetime 
and the metric induced by the matter fields. The modified Einstein 
equations obtained from this action reduce to the Einstein equations 
with zero cosmological constant in the regime of low coupling. By 
introducing the G-field, which acts as a set of Lagrangian multipliers, 
the proposed entropic action reduces to a dressed Einstein-Hilbert 
action with an emergent small and positive cosmological constant only 
dependent on the G-field. The obtained equations of modified gravity 
remain second order in the metric and in the G-field. A canonical 
quantization of this field theory could bring new insights into quantum 
gravity while further research might clarify the role that the G-field 
could have for dark matter.
We furthermore show that the geometrical quantum relative entropy 
associated to the Schwarzschild metric, which provides an approximate 
solution of the modified gravity equations, follows the area law for 
large Schwarzschild radius.

/Bianconi, G., 2025. Gravity from entropy. Physical Review D, 111(6), 
p.066001./
/Bianconi, G., 2025. The quantum relative entropy of the Schwarzschild 
black hole and the area law. Entropy, 27(3), p.266/.