Approaches to Quantum Gravity: Toward a New Understanding of Space, Time and Matter 1st Edition

The book published in 2009, while containing the spectrum of main approaches to quantum gravity (QG) then, is predictably outdated in 2020. The large amount of experimental work in cosmological-gravity, gravitational wave observations, astroparticle physics, and proposed testing approaches using quantum information theory (CVQIT - continuous-variable quantum information theory and looking at subalgebras instead of tensor product Hilbert spaces) in Planck mass scale experiments, during the past decade has rendered some approaches less potent than others (no-go theorems). The 2011 ESA Integral gamma-ray experiment, for example, rules out Planck level granularity limit theories. Gravitational-wave (GW) experiments such as from LIGO and LISA, focusing on spin-2 fields only and gravitational lensing timing, might produce tests that look at propagation effects and may rule out various QG models. Not enough emphasis was put on the mathematical prowess and universality of the NCG (non-commutative geometry) spectral action geometry approach which could conceivably bring together many of the seemingly disparate approaches to QG. Causal dynamical triangulation was also not discussed.A long overdue update (2nd Edition) is waiting considering the progress in QG since the publication date. Nonetheless, this is to be expected in theoretical physics subjects and in particular, in QG and TOE. A recent and good experimental test proposal companion book would be Experimental Search for Quantum Gravity, S. Hossenfelder, Ed.

I read a quantum gravity book every decade, to just check if anything has changed. This was a great review, and explains all the pieces. It's amazing how much work is going into QG, and you can almost feel the story of the people working on it. This is the best book on gravity I've read since the Wheeler's book "Gravitation" (in the 1970's).

I have read most of the "popular" (for the non-mathematician)physics books on the market. This is more advanced proceedings of the latest theories which try to reconcile quantum field theory with general relativity, which is currently the Holy Grail of modern physics. The book requires a fair amount of pre-knowledge of the topic. It is excellent for physics majors and physics junkies like myself. It features articles by many of the major contibutors to this field, such as Gerard T'Hooft and Lee Smolin.