Jean-Luc Lehners studied physics and mathematics at Imperial College London and at the University of Cambridge. He obtained his Ph.D. in 2005 at Imperial College for his research in string theory. Following postdoctoral positions at the University of Cambridge, Princeton University, and the Perimeter Institute, he established the Theoretical Cosmology group at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) in Potsdam in 2010, which he ran until 2024. Dr. Lehners won two prestigious ERC Grants. His research focuses on the early universe, with a particular emphasis on quantum effects in cosmology.

• Conventions and notation; 1. Modeling the early universe; 2. Blowing up the universe: inflation; 3. Observing perturbative quantum gravity: fluctuations; 4. Quantizing gravity: canonical approach; 5. Quantizing gravity: path integral approach; 6. Linking gravity, quantum theory, and thermodynamics; 7. Creating space and time: the no-boundary proposal; 8. Interpreting the wave function; 9. Transitioning to different spacetimes; 10. Going deeper yet: stringy cosmology; A. Constants of nature and cosmological quantities; B. Picard–Lefschetz theory and saddle point approximation; C. Useful functions; D. Exercise solutions; E. Guide to the bibliography; References; Index.

'J.-L. Lehners's Quantum Cosmology provides an excellent review of both the well-established pillars and modern developments in the subject. It's perfectly organized and leads the reader from the basics to the forefront of research. Lehners explains a wide spectrum of complex topics, from the observational universe to the highly mathematical Picard–Lefschetz theory, in simple, accessible language. The useful exercises with solutions at the end of each chapter are a very good complement to the main text. In summary, this book is invaluable for scientists at every stage of their careers. Students will find it a perfect introduction to advanced topics, while young scientists can use it as a springboard to the forefront of quantum cosmology research. For senior scientists, it's an excellent way to quickly refresh their knowledge of complex subjects.' George Lavrelashvili, Tbilisi State University

Jean-Luc Lehners studied physics and mathematics at Imperial College London and at the University of Cambridge. He obtained his Ph.D. in 2005 at Imperial College for his research in string theory. Following postdoctoral positions at the University of Cambridge, Princeton University, and the Perimeter Institute, he established the Theoretical Cosmology group at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) in Potsdam in 2010, which he ran until 2024. Dr. Lehners won two prestigious ERC Grants. His research focuses on the early universe, with a particular emphasis on quantum effects in cosmology.

• Conventions and notation; 1. Modeling the early universe; 2. Blowing up the universe: inflation; 3. Observing perturbative quantum gravity: fluctuations; 4. Quantizing gravity: canonical approach; 5. Quantizing gravity: path integral approach; 6. Linking gravity, quantum theory, and thermodynamics; 7. Creating space and time: the no-boundary proposal; 8. Interpreting the wave function; 9. Transitioning to different spacetimes; 10. Going deeper yet: stringy cosmology; A. Constants of nature and cosmological quantities; B. Picard–Lefschetz theory and saddle point approximation; C. Useful functions; D. Exercise solutions; E. Guide to the bibliography; References; Index.

'J.-L. Lehners's Quantum Cosmology provides an excellent review of both the well-established pillars and modern developments in the subject. It's perfectly organized and leads the reader from the basics to the forefront of research. Lehners explains a wide spectrum of complex topics, from the observational universe to the highly mathematical Picard–Lefschetz theory, in simple, accessible language. The useful exercises with solutions at the end of each chapter are a very good complement to the main text. In summary, this book is invaluable for scientists at every stage of their careers. Students will find it a perfect introduction to advanced topics, while young scientists can use it as a springboard to the forefront of quantum cosmology research. For senior scientists, it's an excellent way to quickly refresh their knowledge of complex subjects.' George Lavrelashvili, Tbilisi State University

Jean-Luc Lehners studied physics and mathematics at Imperial College London and at the University of Cambridge. He obtained his Ph.D. in 2005 at Imperial College for his research in string theory. Following postdoctoral positions at the University of Cambridge, Princeton University, and the Perimeter Institute, he established the Theoretical Cosmology group at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) in Potsdam in 2010, which he ran until 2024. Dr. Lehners won two prestigious ERC Grants. His research focuses on the early universe, with a particular emphasis on quantum effects in cosmology.

• Conventions and notation; 1. Modeling the early universe; 2. Blowing up the universe: inflation; 3. Observing perturbative quantum gravity: fluctuations; 4. Quantizing gravity: canonical approach; 5. Quantizing gravity: path integral approach; 6. Linking gravity, quantum theory, and thermodynamics; 7. Creating space and time: the no-boundary proposal; 8. Interpreting the wave function; 9. Transitioning to different spacetimes; 10. Going deeper yet: stringy cosmology; A. Constants of nature and cosmological quantities; B. Picard–Lefschetz theory and saddle point approximation; C. Useful functions; D. Exercise solutions; E. Guide to the bibliography; References; Index.

'J.-L. Lehners's Quantum Cosmology provides an excellent review of both the well-established pillars and modern developments in the subject. It's perfectly organized and leads the reader from the basics to the forefront of research. Lehners explains a wide spectrum of complex topics, from the observational universe to the highly mathematical Picard–Lefschetz theory, in simple, accessible language. The useful exercises with solutions at the end of each chapter are a very good complement to the main text. In summary, this book is invaluable for scientists at every stage of their careers. Students will find it a perfect introduction to advanced topics, while young scientists can use it as a springboard to the forefront of quantum cosmology research. For senior scientists, it's an excellent way to quickly refresh their knowledge of complex subjects.' George Lavrelashvili, Tbilisi State University