Hi there, I am currently doing a project on LQG and I am having troubles grasping the basics. I am just wondering if anyone here could help answer a couple of questions that I have during my study. 1.) How to use Roger Penrose's original spin-network? I read in his book that they are used to calculate probabilities involving atomic or subatomic processes. How exactly does it work? 2.) Why can't we quantize gravity like we did with QED? 3.) I read somewhere that wheeler dewitt equation is similar in function to schrodinger's equation in quantum mechanics. Does wheeler dewitt gives specifically the time evolution of space-time? This research project has proven to be difficult since I have not taken any formal courses in GR and QFT. Thank you very much in advance.