**About the Special Issue Editors**

**Steffen Gielen** studied physics and mathematics in Hannover and Berlin before moving to Cambridge, where he completed Part III of the Mathematical Tripos in 2007 and his Ph.D. in the Relativity and Gravitation Group in 2011. After postdoctoral positions at the Albert Einstein Institute, Perimeter Institute for Theoretical Physics, Imperial College London, and the Canadian Institute for Theoretical Astrophysics, in 2017 he was awarded a University Research Fellowship by the Royal Society. He held the first part of this fellowship (2018–19) at the University of Nottingham, and in October 2019 moved to the University of Sheffield. He received Second Prize in the Buchalter Cosmology Prize competition in 2017. His research currently mostly deals with the application of quantum gravity to early universe cosmology, in particular the possible resolution of the Big Bang singularity through quantum gravity.

**Sylvain Carrozza** studied physics and mathematics at Ecole ´ Normale Superieure ´ de Lyon. He received a Ph.D. in theoretical physics from Paris XI University in 2013, for work completed in collaboration with the Albert Einstein Institute in Potsdam, where he was a long-term visiting graduate student. Since then, he has held postdoctoral positions at Aix-Marseille University, the University of Bordeaux, and Perimeter Institute for Theoretical Physics. His research focuses on quantum gravity, quantum field theory and renormalization, and, more broadly, explores the interplay between mathematical physics and combinatorics. He has more specifically contributed to the renormalization program of group field theory, and to recent developments in the theory of random tensors.

**Daniele Oriti** go<sup>t</sup> his Ph.D. from the University of Cambridge and held research positions at Utrecht University and Perimeter Institute for Theoretical Physics. He directed a research group on quantum gravity at the Albert Einstein Institute for Gravitational Physics, Potsdam, until 2019. He is currently a senior researcher and group leader at the Arnold Sommerfeld Center for Theoretical Physics of the Ludwig-Maximilians-University in Munch, Germany. His research interests span quantum gravity, broadly intended, with specific focus on group field theory formalism, and related subjects, like discrete quantum gravity and loop quantum gravity, as well as fundamental cosmology and quantum black holes. He maintains also an active interest in the foundations of physics and the philosophy of science.
