Quantum Gravity

Quantum gravity is perhaps the most important open problem in fundamental physics. It is the problem of merging quantum mechanics and general relativity, the two great conceptual revolutions in the physics of the twentieth century. This book discusses the many aspects of the problem, and presents technical and conceptual advances towards a background-independent quantum theory of gravity, obtained in the last two decades. The first part of the book is an exploration on how to re-think basic physics from scratch in the light of the general-relativistic conceptual revolution. The second part is a detailed introduction to loop quantum gravity and the spinfoam formalism. It provides an overview of the current state of the field, including results on area and volume spectra, dynamics, extension of the theory to matter, applications to early cosmology and black-hole physics, and the perspectives for computing scattering amplitudes. The book is completed by a historical appendix which overviews the evolution of the research in quantum gravity, from the 1930s to the present day.