This year's GIFT Seminar reviewed some recent developments and new perspectives on Quantum Gravity and Quantum Cosmology. The topics treated at a graduate level include an Introduction to Quantum Gravity, Path Integral Measure, Non-Perturbative Canonical Formulation (Ashtekar's variable, loop space quantization). Topics on Quantum Cosmology include the Cosmological Constant Problem, Minisuperspace Models, Wormholes and Baby Universes, and Inflationary Cosmology.
General Relativity and Gravitation 1992 contains the best of 700 papers presented at the tri-annual INT conference, generally recognized as the key conference in the area. The plenary and invited papers are published in full, along with summaries of parallel symposia and workshops. The list of plenary speakers is as impressive as ever, with contributions from Jim Hartle, Roger Penrose, and Lee Smolin among many others.
This book presents a selection of Prof. Matteo Campanella’s writings on the interpretative aspects of quantum mechanics and on a possible derivation of Born's rule – one of the key principles of the probabilistic interpretation of quantum mechanics – that is independent of any priori probabilistic interpretation. This topic is of fundamental interest, and as such is currently an active area of research. Starting from a natural method of defining such a state, Campanella found that it can be characterized through a partial density operator, which occurs as a consequence of the formalism and of a number of reasonable assumptions connected with the notion of a state. The book demonstrates that the density operator arises as an orbit invariant that has to be interpreted as probabilistic, and that its quantitative implementation is equivalent to Born's rule. The appendices present various mathematical details, which would have interrupted the continuity of the discussion if they had been included in the main text. For instance, they discuss baricentric coordinates, mapping between Hilbert spaces, tensor products between linear spaces, orbits of vectors of a linear space under the action of its structure group, and the class of Hilbert space as a category.
Today we are blessed with two extraordinarily successful theories of physics. The first is Albert Einstein's general theory of relativity, which describes the large-scale behaviour of matter in a curved spacetime. This theory is the basis for the standard model of big bang cosmology. The discovery of gravitational waves at the LIGO observatory in the US (and then Virgo, in Italy) is only the most recent of this theory's many triumphs. The second is quantum mechanics. This theory describes the properties and behaviour of matter and radiation at their smallest scales. It is the basis for the standard model of particle physics, which builds up all the visible constituents of the universe out of collections of quarks, electrons and force-carrying particles such as photons. The discovery of the Higgs boson at CERN in Geneva is only the most recent of this theory's many triumphs. But, while they are both highly successful, these two structures leave a lot of important questions unanswered. They are also based on two different interpretations of space and time, and are therefore fundamentally incompatible. We have two descriptions but, as far as we know, we've only ever had one universe. What we need is a quantum theory of gravity. Approaches to formulating such a theory have primarily followed two paths. One leads to String Theory, which has for long been fashionable, and about which much has been written. But String Theory has become mired in problems. In this book, Jim Baggott describes
This volume provides a self-contained introduction to applications of loop representations in particle physics and quantum gravity, in order to explore the gauge invariant quantization of Yang-Mills theories and gravity. First published in 1996, this title has been reissued as an Open Access publication on Cambridge Core.
This festschrift was conceived in connection with the symposium 'Topics on Quantum Gravity and Beyond,' held in honor of Louis Witten. The majority of the essays deal with problems on the frontiers of quantum gravity and string theories. There are also articles on atomic, nuclear, and particle physics, to name a few.
These nine essays, commissioned on the initiative of the Philosophy section of the British Academy, address fundamental questions about time in philosophy, physics, linguistics, and psychology. Are there facts about the future? Could we affect the past? In physics, general relativity and quantum theory give contradictory treatments of time. So in the current search for a theory of quantum gravity, which should give way: general relativity or quantum theory? In linguistics and psychology, how does our language represent time, and how do our minds keep track of it?
The XIIIth Brazilian School of Cosmology and Gravitation covered a series of fundamental topics in our current understanding of Cosmology, Astrophysics, and Gravity. The purpose of the School is to give a view of the state of the art of these areas for students and post-docs, and also for the more experienced practitioners. Lectures were delivered by very well-known researchers in topics that covered several areas of theoretical and observational Cosmology, Astrophysics, and Gravitation, ranging from Quantum Gravity to Active Galactic Nuclei.
