Events

Date: 16 October 2025   Time: 14:00 - 15:00

Location: Room 610, G.O. Jones Building

Gravity from Entropy

Gravity is derived from an entropic action coupling matter fields with geometry called Gravity from Entropy action [1]. The fundamental idea is to relate the metric of Lorentzian spacetime to a quantum operator, playing the role of a 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 and curvature. The proposed Gravity from Entropy (GfE) action is associated to a Lagrangian given by a novel geometric quantum relative entropy (GQRE) between the metric of spacetime and the metric induced by the matter fields and curvature which capture the entanglement between geometric degrees of freedom of spacetime. 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, and interpreting it a physical and measurable field, the proposed entropic action reduces to a dressed Einstein-Hilbert action with an emergent 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. Interestingly the GfE action when calculated on Schwarzschild metric allows us to derive from first principles the area law for black holes with large Schwarzschild radius [2]. 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.

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