Modified and Quantum Gravity

This book discusses theoretical predictions and their comparison with experiments of extended and modified classical and quantum theories of gravity. The goal is to provide a readable access and broad overview over different approaches to the topic to graduate and PhD students as well as to young researchers. The book presents both, theoretical and experimental insights and is structured in three parts. The first addresses the theoretical models beyond special and general relativity such as string theory, Poincare gauge theory and teleparallelism as well as Finsler gravity. In turn, the second part is focused on the observational effects that these models generate, accounting for tests and comparisons which can be made on all possible scales: from the universe as a whole via binary systems, stars, black holes, satellite experiments, down to laboratory experiments at micrometer and smaller scales. The last part of this book is dedicated to quantum systems and gravity, showing tests of classical gravity with quantum systems, and coupling of quantum matter and gravity.

Christian Pfeifer is currently a postdoctoral fellow at the Center of Applied Space Technology and Microgravity (ZARM) at the University of Bremen, Germany. He obtained his Ph.D. in mathematical theoretical physics from the University of Hamburg in 2013. After that, he worked as a postdoc at the University of Hannover (2014-2016), Germany, and at the University of Tartu, Estonia (2017-2020). His work focuses on the use of geometric concepts beyond Riemannian geometry in the description of gravity, quantum gravity phenomenology, and the propagation of fields in media. Moreover, his work addresses the comparison of predictions from classical and quantum gravity with observations on cosmological, astrophysical, and laboratory scales.

Claus Lämmerzahl is an honorary professor at the University of Bremen, Germany, a director of the space science division of the Center of Applied Space Technology and Microgravity (ZARM) since 2012, and a professor of theoretical physics at the University of Oldenburg, Germany, since 2010. He obtained his Ph.D. from the University of Konstanz in 1989, where he also habilitated in 1997. In between, he held several postdoc positions at various universities: Paris, France (1994-1996), Konstanz, Germany (1996-2000), Dusseldorf, Germany (2000-2003), and Bremen (2003-2008). His main research interests include general relativity, relativistic astrophysics, gravity beyond special and general relativity, as well as the interplay between quantum systems and gravity. A particular focus of his research lies on the opportunities to test properties of gravity with quantum systems.