P G Bergmann - Böcker

This volume contains the Proceedings of "Quantum Gravity": a series of qualified lectures of most outstanding scientists given during the XIV Course of the International School of Cosmology and Gravitation. As usual of that School, the Course was conceived for researchers at different levels of scientific maturity ranging from post-doctorate research students to well established research workers: then in every lecture you can find an introduction where a review and analysis of the main mathematical, physical and epistemological difficulties encountered at the formulations of relativistic quantum theories are expounded, ranging from relativistic quantum mechanics and quantum field theory in Minkowski and in curved space-time to the various canonical and covariant approaches to quantum gravity.

The introduction of spin is believed to be a necessary tool if one wishes to quantize general relativity. Then the main problem is to see if the introduction of spin generalizing the general relativity from a geometric point of view, i.e. through the concept of torsion, can be experimentally verified.The reader can find in this book both theoretical and experimental arguments which show the necessity for the introduction of spin, and then of torsion, in gravity. In fact, torsion constitutes the more natural and simple way to introduce spin in general relativity. For that reason it is of fundamental importance to see if there are some experiences that indicate — if not directly, then at least indirectly — the presence of torsion. This book presents a discussion on experiments with a polarized-mass torsion pendulum, the search for galactic dark matter interacting with a spin pendulum, a description of a space-based method for determination of the gravitational constant and space-based measurements of spin in gravity, as well as a discussion on theoretical arguments, for instance the nature of torsion and nonmetricity, the viability of gravitational theories with spin-torsion and spin-spin interaction, many-dimensional gravitational theories with torsion, spinors on curved spaces, the spinors in real space-time, etc.We know that until now there has been no evidence for torsion, but this fact cannot prevent us from considering in some detail this implement of research that seems to be important from both a geometrical and a physical point of view.