What's your pick for the most important paper from among second quarter 2007 non-string quantum gravity research? This short list was narrowed down from a larger number of paper which were flagged by several PF people this time, including Francesca, Jal, and myself. Papers that appear in latter half June can be considered with the third quarter (July-August-September) batch. Here's the list http://arxiv.org/abs/0705.2388 The loop-quantum-gravity vertex-amplitude Jonathan Engle, Roberto Pereira, Carlo Rovelli 6 pages "Spinfoam theories are hoped to provide the dynamics of non-perturbative loop quantum gravity. But a number of their features remain elusive. The best studied one -the euclidean Barrett-Crane model- does not have the boundary state space needed for this, and there are recent indications that, consequently, it may fail to yield the correct low-energy n-point functions. These difficulties can be traced to the SO(4) -> SU(2) gauge fixing and the way certain second class constraints are imposed, arguably incorrectly, strongly. We present an alternative model, that can be derived as a bona fide quantization of a Regge discretization of euclidean general relativity, and where the constraints are imposed weakly. Its state space is a natural subspace of the SO(4) spin-network space and matches the SO(3) hamiltonian spin network space. The model provides a long sought SO(4)-covariant vertex amplitude for loop quantum gravity." http://arxiv.org/abs/0705.2222 Loop Quantum Gravity: Four Recent Advances and a Dozen Frequently Asked Questions Abhay Ashtekar 21 pages, to appear in the Proceedings of the 11th Marcel Grossmann Conference "As per organizers' request, my talk at the 11th Marcel Grossmann Conference consisted of two parts. In the first, I illustrated recent advances in loop quantum gravity through examples. In the second, I presented an overall assessment of the status of the program by addressing some frequently asked questions. This account is addressed primarily to researchers outside the loop quantum gravity community." http://arxiv.org/abs/gr-qc/0703144 Dynamical coherent states and physical solutions of quantum cosmological bounces Martin Bojowald 30 pages, 3 figures "A new model is studied which describes the quantum behavior of transitions through an isotropic quantum cosmological bounce in loop quantum cosmology sourced by a free and massless scalar field. ... an exactly solvable model ... basis for a systematic perturbation theory of loop quantum gravity... remarkably different from what is known for harmonic oscillator coherent states. ... the quantum state ... evolve deterministically through the bounce." http://arxiv.org/abs/0705.4398 The Dark Side of a Patchwork Universe Martin Bojowald 24 pages, 2 figures, Contribution to the special issue on Dark Energy by General Relativity and Gravitation "While observational cosmology has recently progressed fast, it revealed a serious dilemma called dark energy: an unknown source of exotic energy with negative pressure driving a current accelerating phase of the universe. All attempts so far to find a convincing theoretical explanation have failed, so that one of the last hopes is the yet to be developed quantum theory of gravity. In this article, loop quantum gravity is considered as a candidate, with an emphasis on properties which might play a role for the dark energy problem. Its basic feature is the discrete structure of space, often associated with quantum theories of gravity on general grounds. This gives rise to well-defined matter Hamiltonian operators and thus sheds light on conceptual questions related to the cosmological constant problem. It also implies typical quantum geometry effects which, from a more phenomenological point of view, may result in dark energy. In particular the latter scenario allows several non-trivial tests which can be made more precise by detailed observations in combination with a quantitative study of numerical quantum gravity. If the speculative possibility of a loop quantum gravitational origin of dark energy turns out to be realized, a program as outlined here will help to hammer out our ideas for a quantum theory of gravity, and at the same time allow predictions for the distant future of our universe."