This thread is in part belated appreciation of J.S.Engle's seemingly orderly systematic way of doing research, and good writing style. I'm not kidding: a clear widely understandable writing style helps a lot. If you want a well-written review (from basics to latest) of spinfoams he has one here http://arxiv.org/abs/arXiv:1303.4636 It's to be a chapter in Springer's Handbook of Spacetime (at press) ed Ashtekar and Petkov. In July Engle essentially redefined LQC by establishing a symmetry reduced sector of the full LQG theory, and (significantly) doing it in a diffeomorphism invariant way. This politely pulled the rug from under an earlier somewhat over-emphatic criticism of LQC non-covariance. Slides PDF here: http://pirsa.org/13070039 Diffeomorphism invariance and dynamic symmetry reduction Video starts at minute 83:00 of http://pirsa.org/displayFlash.php?id=13070039 Two of Engle's students gave talks at Loops 2013 Matthew Hogan's talk starts at minute 51:00 of http://pirsa.org/13070087 Atousa Shirazi's talk starts at minute 64:00 of http://pirsa.org/13070086 By way of general introduction, here's part of what Inspire's page says. http://inspirehep.net/author/J.S.Engle.1/ Florida Atlantic FAC 2010 U. Erlangen PD 2009 2010 CPT, Marseille PD 2009 2009 MPI, Potsdam PD 2007 2009 CPT, Marseille PD 2006 2007 Penn State U. PHD 2001 2006 Ashtekar was his PhD advisor, collaboration with Ashtekar, Rovelli, Thiemann and many others. The "E" in EPRL. What got my attention yesterday was the Shirazi Engle paper. I think it is a major step forward in the spinfoam program: something that needed to be done. What impressed me was the orderly deliberateness (and the clear writing).