### Project Description

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RESEARCH AREAS:

Loop quantum gravity

Black hole physics

Foundations of quantum gravity

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# FARSHID SOLTANI

**Doctoral Student;**

Department of Physics & Astronomy, Western University

My main research interest is in quantum gravity, both at the foundational level and at the level of physical applications. The focus of my PhD project is the investigation of the end of the life of a black hole. The fact that black holes are not eternal was proven by Hawking who showed that they actually evaporate. Namely, using quantum field theory on curved spacetime he showed that black holes emit a thermal radiation and that consequently they slowly lose mass. To study the end of the life of black holes, that is the end of the evaporation process, it is however necessary to take into account that after a sufficiently amount of time the quantum nature of the gravitational field can no longer be neglected and quantum field theory on curved spacetime is not a good approximation anymore. The end of the life of black holes must then be studied using quantum gravity. A very natural and conservative scenario for the end of the life of a black hole is the one in which the black hole geometry undergoes a quantum transition into a white hole geometry. This conjectured astrophysical phenomenon is able to concretely answer some of the most significant and renowned open questions in classical and quantum general relativity. In this scenario the classical singularity in the interior of a black hole is replaced by a smooth transition of the interior geometry of the black hole in the interior geometry of a white hole, thus supporting the conjecture that classical curvature singularities are only an indication that the classical theory can no longer be trusted in that region. It is the only tentative scenario for the end of the life of a black hole that is driven by quantum gravity considerations. It is the only tentative mechanism for the astrophysical production of white holes. Furthermore, it is able to naturally solve the information loss paradox: all the information fallen inside the black hole can simply come out of the white hole. The main objective of my research project is to investigate the physics of this phenomenon using loop quantum gravity. This analysis will hopefully improve the understanding of the very rich phenomenology of this scenario.

Fabio D’ambrosio, Marios Christodoulou, Pierre Martin-Dussaud, Carlo Rovelli and Farshid Soltani. “End of a black hole’s evaporation”. *Physical Review* D 103 (2021). DOI: 10.1103/PhysRevD.103.106014. arXiv: 2009.05016 [gr-qc].

Farshid Soltani, Carlo Rovelli and Pierre Martin-Dussaud. “End of a black hole’s evaporation. II”. *Physical Review* D 104 (2021). DOI: 10.1103/PhysRevD.104.066015. arXiv: 2105.06876 [gr-qc].