Covariant Loop Quantum Gravity

This is an exciting subject to read about. The opening pages discuss how at the scale of ten to the power of minus thirty three centimeters , the Planck scale , strange things happen. General relativity predicts that a particle confined to a very small space should form a black hole. The Schwarzschild radius is proportional to the mass of the particle assuming the particle is sufficiently concentrated to form a black hole. General relativity allows the Schwarzschild radius to be arbitrarily small. Giving correct numerical factors and combining the argument with Quantum Mechanics in terms of the Heisenberg uncertainty principal predicts a minimum size for the localization and this turns out to be Plank scale. This argument is detailed in the book by the authors with correct numerical factors given. The argument is in some ways academic because micro-black holes probably do not exist but it does show an inherit contradiction between General Relativity and Quantum Mechanics. The argument also shows the scale at which we expect quantum gravity to be important. The argument outlined was given by Bronstein an early pioneer of Quantum Gravity. Quantum Gravity is important for example to understand early cosmology of the universe but mostly it is to try to resolve the inherit contradictions between Quantum Theory and General Relativity. These contradictions can be seen in other ways. The book requires understanding of SU(2), SO(1,3), and their irreducible representations in spinor space. Very early on by looking at a tetrahedron and postulating a quantum relation similar to that of angular momentum in elementary quantum mechanics we deduce that area is quantized for the tetrahedron (just as the total angular momentum is quantized in quantum mechanics). We also deduce that distance itself has a fuzziness at this scale! The book proceeds from there. The book is not "elementary" since there is much impressive math and physics but this should not put one off reading this book but instead be motivation for reading from external sources to fill in the gaps and gain a better understanding of this exciting subject. To me it does seem like this theory is the correct theory for uniting General Relativity and Quantum Theory rather than thinking about higher dimensional spaces and as further evidence of this there is a chapter (Chapter 8, Continuum limit) showing how in outline Einstein's equations can be deduced from these spinor equations. A complete understanding would only be achieved by a specialist in the field but this should not put one off reading about what has been achieved. The ideas here will definitely expand your horizons and this is a must to read for anyone interested in Physics. However to gain the most from this book supplementary reading will definitely be necessary.

The problem with readability of the equations has been fixed in the version I downloaded. This introduction is very readable, but as others have stated it does require considerable prior knowledge and facility with QM and GR.

Quantum Loop Gravity made me quantumly loop my gravity.

Though there are parts of the text that could use a clearer exposition (as with any advanced text on a broad subject in theoretical physics), the authors worked very hard to provide a clear introduction to LQG. I found this introduction very accessible ("accessible" is a relative term), at least to someone who has had the fortune of receiving a graduate-level education in physics. They try to make the book as self-contained as possible, though it would be helpful to have had an introduction to general relativity at the level of Sean Carroll's book and to have had at least an undergraduate-level introduction to quantum mechanics (some knowledge of quantum field theory would be preferable, but not necessary). For folks don't have a formal education in physics but want to learn about LQG, these are the two broad subjects I'd personally recommend building an understanding of before jumping into this book.

Compared to other textbooks of quantum gravity the approach is rigorous as well, but the description is extensive and in some way self contained. A lot of effort and attention is devoted to make the extremely sophisticated physical concepts and mathematical formalism understandable. Effective in explaining the inner features of reality.

Misses it's goal a bit, it wasn't quite as low level as the authors anticipated. The preface states "assumes only some basic knowledge of general relativity, quantum mechanics and quantum field theory." This is very untrue, you must know considerably more than this. The middle chapters require you to be quite comfortable with differential forms and alternative formulations of the Einstein-Hilbert action. That being said, if you rewrite that sentence to assume comfort with GR, QFT and differential geometry, this book is the best book hands down for learning covariant LQG.

Yes it is a good book. It is difficult for me and must be read slowly.

As the title of thsThis evaluation (3 stars) is not to degrade the context of this excellent book. But if you are to order this book, you better go with the printed version and not the Kindle one, as will you really find it difficult and bothering reading the mathematical equations, terms, and symbols in their scanned form that appear quite small and faded if not illegible. There is no way you can enlarge such scanned "images". It is really frustrating that e-books cannot follow (or imitate) the advanced standard or the format of PDF texts in which there is no difference between ordinary texts and specialized symbols or formulas either in their sharpness or size. I hope sometimes Kindle takes care of this problem. Mind, it is not a wishful thinking since it is surely doable, provided that a plethora of serious consumers (readers) demand it from Amazon or Kindle. Recall that in early versions of Kindle book it was impossible to refer to the page number of a scholarly book or any book you were reading (only the digital "locaton" was given), but this flaw does is already dealt with (the page number is now given in the Kindle edition as you click on a line).

Plus en profondeur que bien des livres de vulgarisation

The best book about LQG.

This book is a very readable, even if technical, introduction to Loop Quantum Gravity that Carlo Rovelli significantly helped to establish. Some knowledge of quantum field theory and general relativity is needed but at undergraduate level. Very nice explanation of surface and volume quantization that are pivotal results obtained by Rovelli and Lee Smolin during the initial development of the theory. All in all, this book represents an easy way to be introduced to the realm of quantum gravity for a serious student through a careful explanation of one of the main theories that try to address such a question.

This book can be highly recommended to all those interested in Quantum Gravity and Loop Quantum Gravity. It reviews the basics of General Relativity and Quantum Field Theory before introducing 3d and 4d Loop Quantum Gravity. It has numerous exercises which are valuable for those using the text for study purposes. It is very clearly written with nice prose and we'll explained mathematical sections.

L’article lui-même correspond parfaitement à mon attente, cependant il a été livré (heureusement sans dommage) dans un paquet presque entièrement ouvert sur un coté, l'ouvrage étant sans autre protection à l'intérieur.